This is a Occultation measurement covering the time 2007-06-03T05:34:44.050 to 2007-06-03T07:08:15.950. This data set contains archival raw, processed, and supporting radio science Doppler data acquired from the Venus Express Radio Science Experiment (VeRa). The data were recorded using the closed loop receiver facilities at the European Space Agency (ESA) groundstations or at the NASA Deep Space Network (DSN) groundstations. The data set contains one Venus measurement recorded in earth occultation geometry starting before the ingress (ingoing) phase and ending after the egress (outgoing) phase of the occultation pass. The data can be used to derive electron density profiles in the ionosphere and profiles of neutral number density, pressure and temperature in the neutral atmosphere of Venus. The neutral atmosphere profiles deduced from these occultation measurements usually cover the altitude range between about 45 - 90 km.
Description
Data Set Overview ================ The Venus Express (VEX) Radio Science (VeRa) Data Archive is a time-ordered collection of raw and partially processed data collected during the Venus Express Mission. This is a Occultation measurement covering the time 2007-06-03T05:34:44.050 to 2007-06-03T07:08:15.950. VeRa radio occultation observations start shortly before the occultation ingress, when the VEX spacecraft moves behind the planetary disk as seen from the Earth and stop shortly after the occultation egress, when the probe emerges from behind the planet. VeRa occultation data usually cover three recording phases: the occultation ingress (1), the time when the spacecraft is occulted by the planet (2) and the occultation egress (3). The different observation phases can be distinguished by regarding the AGC data, which records the strength of the received signal. In phase (1) and (3) the AGC level is high compared to phase (2). In Phase (2) still a signal may be received at the groundstation due to the strong bending of the radio waves in the dense atmosphere. The strength of the signal is significantly reduced and weakens further the deeper the radio waves penetrate the atmosphere until the groundstation may be unable to lock. Therefore, the beginning of phase (2) is recognized at first order by a sharp drop of the AGC down to -95 dB and lower and ends with a sharp rise in the AGC data back to the former AGC level. For the derivation of higher science products it is recommended to divide the level 2 data into an ingress and an egress part and to process these data seperatetly. This is a radio occultation measurement of the Venusian atmosphere. It was done during occultation by the planet during the third occultation season from 2007-04-26 to 2007-06-25. The number of occultation measurements during the third occultation season can be found in DOCUMENT/VRA_DOC/VERA_OPS_LOGBOOK_07.PDF. It should be noted, that the occultation seasons within the VERA_OPS_LOGBOOK_07.PDF only comprise the radio science measurements and can therefore deviate from the occultation seasons defined in CATALOG/MISSION.CAT and DOCUMENT/VRA_DOC/VEX_MISSION_CALENDAR.PDF. For more information on the investigations proposed see the VeRa User Manual VRAUSERMANUAL2005 in the DOCUMENT/VRA_DOC folder. For more information about VeRa measurements see INST.CAT or the VeRa User Manual VRAMANUAL2005. This data set was collected during the VEX science subphase 7 (PH7) 2007. For more information see MISSION.CAT. Mission Phase Definition ------------------------ The mission phases which are used in the Data Set Identifier DATA_SET_ID correspond to the following table: Phase name | abbreviation | time span ================================================================ Nominal Mission Phase | NMP | 2005-11-09 - 2007-10-02 ---------------------------------------------------------------Extended Mission 1 | EXT1 | 2007-10-03 - 2009-05-31 ---------------------------------------------------------------Extended Mission 2 | EXT2 | 2009-06-01 - tbd The mission phases are further divided into science subphases. Mission phase and science subphase definitions can be found in CATALOG/MISSION.CAT and DOCUMENT/ESA_DOC/VEX_ARCHIVE_CONVENTIONS.PDF. Data files ---------- Data files are: the tracking files from Deep Space Network (DSN) and from the Intermediate Frequency Modulation System (IFMS) used by the ESA ground station New Norcia, Level 1a to level 2 data are archived, the predicted and reconstructed Doppler and range files, the Geometry files. All Level 1a binary data files will have the file name extension eee = .DAT IFMS Level 1a ASCII data files will have the file name extension eee = .RAW Level 1b and 2 tabulated ASCII data files will have the file name extension eee = .TAB Binary data files will have the file name extension .DAT Data levels ----------- It should be noted that these data levels which are also used in the file names and data directories are PSA data levels whereas in the PDS label files CODMAC levels are used. PSA data level | CODMAC level ----------------------------- 1A | 1 1B | 2 2 | 3 Data Set Identifier ------------------- The DATA_SET_ID is a unique alphanumeric identifier for the data sets. It looks something like: XXX-Y-ZZZ-U-VVV-NNNN-WWW Acronym | Description | Example -------------------------------------------------------- XXX | Instrument Host ID | VEX -------------------------------------------------------- Y | Target ID | V (for Venus) or X for | | others like for example | | the sun during solar | | conjunction measurements -------------------------------------------------------- ZZZ | Instrument ID | VRA -------------------------------------------------------- U | Data level (here | 1/2/3 (Data set | CODMAC levels are used) | contains raw, edited | | and calibrated data) --------------------------------------------------------- VVV | VRA mission phase | VOI --------------------------------------------------------- NNNN | 4 digit sequence number | 0123 | which is identical to | | the Radio Science | | Volume_id | --------------------------------------------------------- WWW | Version number | V1.0 VeRA data were originally archived as volumes rather than data sets. However, ESA PSA does not uses volume but data sets. To avoid confusion it was specified that one VeRa data volume is equal one data set. Thus the data set was also assigned a 4 digit sequence number which is identical to the one used in the Radio Science volume_id. If the data_set_id is known it is automatically specified on which volume the data set is found. VOLUME_ID --------- The VOLUME_ID is a unique alphanumeric identifier for volume. The Volume ID provides a unique identifier for a single MaRS, RSI or VeRa data volume, typically a physical CD-ROM or DVD. The volume ID is also called volume label by the various CDROM recording software packages. The Volume ID is formed using a mission identifier, an instrument identifier of 3 charac- ters, followed by an underscore character, followed by a 4 digit sequence number. In the 4-digit number, the first one represents the volume set, the remaining digits define the range of volumes in the volume set. For Mars Express the first digit is not defined after the kind of measurement (see below for Rosetta and VEX), but after the Mission phase. 0000: Commissioning 1000: Occultation 2000: Gravity 3000: Solar Conjunction 4000: Bistatic Radar 5000: Passive/Active Checkouts 6000: Swing-bys/Fly-bys 7000: Cometary Coma Observations It looks something like: XXXXXX-ZZZZ Acronym | Description | Example ---------------------------------------------------------- XXXXXX | Instrument Host and Instrument ID | VEXVRA ---------------------------------------------------------- ZZZZ | 4 digit sequence number | 0123 Important note: the here defined ESA PSA Volume_Id is not identical with the Radio Science Volume_Id. The Radio Science Volume_Id is a number which is incremented measurement by measurement, independent what kind of measurement was conducted. The Radio Science Volume_Id belonging to one single measurement can be find in the Logbook, loca- ted in the folder DOCUMENT/VRA_DOC. Descriptive files ----------------- Descriptive files contain information in order to support the processing and analysis of data files. The following file types are defined as descriptive files with extension eee = .LBL PDS label files .CFG IFMS configuration .AUX Anxiliary files (event files, attitude files, ESOC orbit files, products, SPICE files) .TXT Information (text) files File naming convention ====================== All incoming data files will be renamed and all processed data files will be named after the following file naming convention format. The original file name of the incoming tracking data files will be stored in the according label file as source_product_id. The new PDS compliant file name will be the following: rggttttlll_sss_yydddhhmm_qq.eee Acronym | Description | Examples ============================================================= r | space craft name abbreviation | V | R = Rosetta | | M = Mars Express | | V = Venus Express | ------------------------------------------------------------- gg | Ground station ID: | 43 | | | 00: valid for all ground stations; | | various ground stations or independent | | of ground station or not feasible to | | appoint to a specific ground station or | | complex | | | | DSN complex Canberra: | | --------------------- | | 34 = 34 m BWG (beam waveguide) | | 40 = complex | | 43 = 70 m | | 45 = 34 m HEF (high efficiency) | | | | ESA Cebreros antenna: | | --------------------- | | 62 = 35 m | | | | DSN complex Goldstone: | | ---------------------- | | 10 = complex | | 14 = 70 m | | 15 = 34 m HEF | | 24 = 34 m BWG | | 25 = 34 m BWG | | 26 = 34 m BWG | | 27 = 34 m HSBWG | | | | ESA Kourou antenna: | | ------------------- | | 75 = 15 m | | | | DSN complex Madrid: | | ------------------- | | 54 = 34 m BWG | | 55 = 34 m BWG | | 63 = 70 m | | 65 = 34 m HEF | | 60 = complex | | | | ESA New Norcia antenna: | | ----------------------- | | 32 = 35 m | ------------------------------------------------------------- tttt | data source identifier: | TNF0 | | | Level 1A and 1B: | | ---------------- | | ODF0 = ODF closed loop | | TNF0 = TNF closed loop (L1A) | | T000-T017 = TNF closed loop (L1B) | | ICL1 = IFMS 1 closed loop | | ICL2 = IFMS 2 closed loop | | ICL3 = IFMS RS closed loop | | IOL3 = IFMS RS open loop | | R1Az = RSR block 1A open loop | | R1Bz = RSR block 1B open loop | | R2Az = RSR block 2A open loop | | R2Bz = RSR block 2B open loop | | R3Az = RSR block 3A open loop | | R3Bz = RSR block 3B open loop | | z=1...4 subchannel number | | ESOC = ancillary files from ESOC DDS | | DSN0 = ancillary files from DSN | | SUE0= ancillary and information files | | coming from Stanford University | | center for radar astronomy | | | | Level 2: | | ------- | | UNBW = predicted and reconstructed | | Doppler and range files | | ICL1 = IFMS 1 closed loop | | ICL2 = IFMS 2 closed-loop | | ICL3 = IFMS RS closed-loop | | ODF0 = DSN ODF closed loop file | | T000-T017 = TNF closed loop file | | RSR0 = DSN RSR open loop file | | RSRC = DSN RSR open loop file containing | | data with right circular | | polarization (only solar | | conjunction measurement) | | RSRL = DSN RSR open loop file containing | | data with left circular | | polarization (only solar | | conjunction measurement) | | NAIF = JPL or ESTEC SPICE Kernels | | SUE0 = ancillary information and | | calibration files coming from | | Stanford University center for | | radar astronomy | | GEOM = geometry file | | | --------|------------------------------------------|-------- lll | Data archiving level | L1A | L1A = Level 1A | | L1B = Level 1B | | L02 = Level 2 | | L03 = Level 3 | --------|------------------------------------------|-------- sss | data type | | | | IFMS data files level 1A: | | ------------------------- | | D1X uncalibrated Doppler 1 X-Band | | D1S uncalibrated Doppler 1 S-Band | | D2X uncalibrated Doppler 2 X-Band | | D2S uncalibrated Doppler 2 S-Band | | C1X Doppler 1 X-Band equip. calibration | | C1S Doppler 1 S-Band equip. calibration | | C2X Doppler 2 X-Band equip. calibration | | C2S Doppler 2 S-Band equip. calibration | | RGX uncalibrated X-Band range | | RGS uncalibrated S-Band range | | MET meteo file | | AG1 AGC 1 files | | AG2 AGC 2 files | | RCX X-Band range equip. calibration | | RCS S-Band range equip. calibration | | | | DSN data files level 1A: | | ------------------------- | | ODF original orbit files (closed loop) | | RSR radio science receiver open-loop file| | TNF file (closed loop) | | | | ESOC ancillary data level 1A: | | ----------------------------- | | ATR attitude file, reconstructed | | EVT orbit event file | | OHC orbit file, heliocentric cruise | | OVO orbit file, venuscentric, operational| | | | DSN Calibration files level 1A: | | ------------------------------- | | TRO DSN tropospheric calibration model | | MET DSN meteorological file | | ION DSN ionospheric calibration model | | BCL SUE Bistatic radar temperature | | calibration | | | | DSN ancillary data level 1A: | | ----------------------------- | | DKF DSN Keyword File | | MON DSN monitor data | | NMC DSN Network Monitor and Control file | | SOE DSN Sequence of Events | | EOP DSN earth orientation parameter file | | ENB SUE Experimenter Notebook | | MFT SUE Manifest files | | LIT DSN Light time file | | HEA DSN Data collection list | | OPT DSN Orbit and timing geometry file | | | | DSN Browse Plots level 1A: | | -------------------------- | | BRO bistatic radar 4-panel plots (browse)| | | | IFMS data files level 1B: | | ------------------------- | | D1X uncalibrated Doppler 1 X-band | | D1S uncalibrated Doppler 1 S-band | | D2X uncalibrated Doppler 2 X-band | | D2S uncalibrated Doppler 2 S-band | | C1X Doppler 1 X-band equip. calibration | | C1S Doppler 1 S-band equip. calibration | | C2X Doppler 2 X-band equip. calibration | | C2S Doppler 2 S-band equip. calibration | | RGX uncalibrated X-band range | | RGS uncalibrated S-band range | | MET meteo | | AG1 AGC 1 | | AG2 AGC 2 | | RCX X-band range equip. calibration | | RCS S-band range equip. calibration | | | | DSN ODF data files level 1B: | | ----------------------------- | | DPS S-band Doppler | | DPX X-band Doppler | | RGS uncalibrated S-Band ranging file | | RGX uncalibrated X-Band ranging file | | RMP uplink frequency ramp rate file | | | | DSN calibration data level 1B: | | ----------------------------- | | MET meteorological file | | | | IFMS data level 2: | | ----------------- | | D1X uncalibrated Doppler 1 X-Band | | D1S uncalibrated Doppler 1 S-Band | | D2X uncalibrated Doppler 2 X-Band | | D2S uncalibrated Doppler 2 S-Band | | RGX uncalibrated X-Band range | | RGS uncalibrated S-Band range | | RCX X-Band range equip. calibration | | RCS S-Band range equip. calibration | | | | IFMS Browse plots level 2 | | ------------------------- | | B1X Quick look plots of calibrated | | Doppler 1 X-band | | B1S Quick look plots of calibrated | | Doppler 1 S-band | | B2X Quick look plots of calibrated | | Doppler 2 X-band | | B2S Quick look plots of calibrated | | Doppler 2 S-band | | | | DSN level 2 data: | | ----------------- | | DPX calibrated Doppler X-band | | DPS calibrated Doppler S-band | | RGS calibrated S-band ranging file | | RGX calibrated X-band ranging file | | BSR bistatic radar power spectra | | SRG bistatic radar surface reflection | | geometry file | | | | DSN level 2 calibration data: | | ---------------------------- | | SRF Surface Reflection Filter Files | | | | orbit files level 2: | | -------------------- | | PTW Doppler & range prediction two-way | | PON Doppler & range prediction on | | RTW reconstructed Doppler & range orbit | | file two-way | | RON reconstructed Doppler & range orbit | | file one-way | | LOC heliocentric state vector file | | | | Constellation file Level 2: | | --------------------------- | | MAR Mars constellation file | | VEN Venus constellation file | | P67 Churyumov-Gerasimenko | | constellation file | | | | SPICE kernel files level 2: | | --------------------------- | | BSP binary spacecraft/location | | kernel file | | FRM frame kernel file | | ORB orbit numbering file | | PBC predicted attitude kernel file | | PCK planetary constant kernel | | SCK space craft clock kernel | | TLS leap second kernel file | | | | Science data level 3: | | --------------------- | | SCP solar corona science | --------|------------------------------------------|-------- yy | Year | 05 --------|------------------------------------------|-------- ddd | Day of year | 153 --------|------------------------------------------|-------- hhmm | Sample hour, minute start time | 1135 | For IFMS files this is the ESOC | | reference time tag which usually | | coincides with the first sample time. | | For IFMS Ranging files however this is | | not true. Here the reference time tag | | is two-way light time before the first | | actual measurement. | --------|------------------------------------------|-------- qq | Sequence or version number | 01 --------|------------------------------------------|-------- eee | .DAT binary files (Level 1A) | .RAW | .TAB ASCII table data file | | .AUX ancillary file | | .CFG IFMS configuration file (Level 1B) | | .LBL PDS label files | | .TXT information files | | .RAW ASCII data files (Level 1A) | | .LOG Processing log files (Level 2) | Processing (DSN) ================ TNFs are screened for bad data points by the JPL Radio Metric Data Conditioning Team (RMDCT) before the files are processed to ODFs. The TNFs included in this archive, however, are the prescreened versions. The open-loop (RSR) data in the archive have been assembled from individual records (packets) into files. They have not otherwise been processed. The Level 2 radio occultation data have been processed as follows: The RSR samples were digitally filtered to reduce bandwidth; in the process they were also converted from 16-bit I and 16-bit Q complex integer samples to 64-bit I and 64-bit Q double precision complex floating point samples. The complex floating point samples were Fourier transformed and estimates made of the carrier amplitude and frequency and their uncer- tainties. The reconstructed spacecraft trajectory, planetary epheme- redes, records of uplink and downlink tuning, and other data were used to calculate the expected carrier frequency at the receiving antenna. The Level 2 products are tables of the observed amplitude, its uncertainty, the observed frequency, its uncertainty, and the difference between the observed and the expected frequency as a function of time. Separate tables have been created for each RSR. The Level 2 bistatic radar spectra (SPC) have been processed as follows: The RSR samples were converted from 16-bit I and 16-bit Q complex integer samples to 64-bit I and 64-bit Q double precision complex floating point samples. In the process they were digitally corrected for non-uniform spectral response of the receiving system. This was done by computing spectra from series of time samples and dividing each spectrum by the square root of a power spectrum computed from many minutes of noise. The amplitude of the samples was then adjusted so that power spectra in each receiver channel would have an amplitude proportional to kTsysB where k is Boltzmanns constant, Tsys is the receiver system temperature in Kelvin, and B is the width of one frequency bin (spectral resolution) in the power spectrum. Then the power spectra (e.g., XR*conj(XR)) and cross spectra (e.g., XR*conj(XL)) were computed. Structure of DATA Directory =========================== Please note that the following description lists all possible subfolders. If however there is no data to fill some of these folders they will not be generated. |-DATA | |-LEVEL1A | | |-CLOSED_LOOP | | | |-DSN | | | | |-ODF Orbit Data Files | | | | |-Tracking and Navigation Files | | | | | | | |-IFMS | | | |-AG1 Auto Gain Control 1 data files | | | |-AG2 Auto Gain Control 2 data files | | | |-DP1 Doppler 1 data files | | | |-DP2 Doppler 2 data files | | | |-RNG Ranging data files | | | | | |-OPEN_LOOP | | | |-DSN | | | | |-RSR Radio-Science Receiver data files | | | | | | |-IFMS | | |-AG1 Auto Gain Control 1 data files | | |-AG2 Auto Gain Control 2 data files | | |-DP1 Doppler 1 data files | | |-DP2 Doppler 2 data files | | |-RNG Ranging data files | | | |-LEVEL1B | | |-CLOSED_LOOP | | | |-DSN | | | | |-ODF Orbit Data Files | | | | | | | |- IFMS | | | | |- AG1 Auto Gain Control 1 data files | | | | |- AG2 Auto Gain Control 2 data files | | | | |- DP1 Doppler 1 data files | | | | |- DP2 Doppler 2 data files | | | | |- RNG Ranging data files | | | | | |- OPEN_LOOP | | | |-IFMS | | | | |-AG1 Auto Gain Control 1 data files | | | | |-AG2 Auto Gain Control 2 data files | | | | |-DP1 Doppler 1 data files | | | | |-DP2 Doppler 2 data files | | | | |-RNG Ranging data files | | | |-LEVEL2 | | |- CLOSED_LOOP | | | |- DSN | | | | |-ODF Orbit Data Files | | | | | | | |- IFMS | | | | |-DP1 Doppler 1 data files | | | | |-DP2 Doppler 2 data files | | | | |-RNG Ranging data files | | | | | |- OPEN_LOOP | | | |-DSN | | | | |-BSR Bistatic radar power spectra | | | | |-SRG Bistatic radar surface reflection | | | | | geometry file | | | | |-DPX Doppler X-Band files | | | | |-DPS Doppler S-Band files | | | | | | | |-IFMS | | | | |-DP1 Doppler 1 data files | | | | |-DP2 Doppler 2 data files | | | | |-RNG Ranging data files Files in the DATA Directory --------------------------- Files in the DATA directory are: Data Level 1A: -------------- Level 1A data are incoming raw tracking data files obtained either from ESA IFMS or DSN. All incoming data files will be renamed after the file naming convention format defined in section 5.1 of the VeRA File Naming Convention document VRAFNC2005 and get a minimal detached label file .LBL. The original file name of the incoming tracking data files will be stored in the according label file as SOURCE_PRODUCT_ID. These files have the file extension .RAW if ASCII and .DAT if binary files. TNFs are screened for bad data points by the JPL Radio Metric Data Conditioning Team (RMDCT) before the files are processed to ODFs. The TNFs included in this archive, however, are the prescreened versions. Tracking and Navigation Files (TNF Directory) --------------------------------------------- TNFs became available within a few hours of the completion of a Venus Express pass. Orbit Data Files ---------------- ODFs were typically issued daily throughout the VEX mission with weekend data being consolidated into a single file on Monday. Typical ODFs have sizes 15-50 kB. Sample rates typically are 1/sec or 1/(60 sec). Radio Science Receiver Files (RSR Directory) -------------------------------------------- Each RSR generated a stream of packets which could be assembled into files of arbitrary length. It was decided, after some experimentation, that files containing about 300 MB were the largest that could be easily manipulated in the analysis computers available in 2003. With a small number of exceptions, this is the largest file size that will be found in the RSR directory. The open-loop (RSR) data in the archive have been assembled from individual records (packets) into files. They have not other- wise been processed. IFMS Data Level 1B: ------------------- Level 1B files are created from level 1A (raw tracking data) as edited ASCII formatted file. Three files are generated for each ESA IFMS Level 1A data file: Level 1B IFMS data file (extension .TAB) Level 1B IFMS configuration file (extension .CFG) Level 1B IFMS label file (extension .LBL) The label file contains the description of the .TAB as well as of the .CFG file. Up to eight files are generated for each DSN ODF Level 1A file: Level 1B ODF Doppler S-Band data file + label file Level 1B ODF Doppler X-Band data file + label file Level 1B ODF Ranging S-Band data file + label file Level 1B ODF Ranging X-Band data file + label file Cologne is processing IFMS and ODF data, Stanford University processes RSR data up to level 2 and forwards raw and processed data to Cologne for archiving. However, for RSR there will be no level 1B files. Data Level 2: ------------- Level 2 data are calibrated data after further processing. The file format is in ASCII. This data level can be used for further scientific interpretation. The keyword OBSERVATION_TYPE in the Level 2 data labels indicates which kind of measurement was done. Keyword values are: Occultation, Target Gravity, Solar Conjunction, Bistatic Radar, Commissioning. Commissioning measurements were carried out on several days during the cruise phase and after Venus Express orbit insertion. These are measurements where the equipment on board the spacecraft and on the ground station was tested, as well as the different confi- gurations for the different kinds of measurements. IFMS Level 2 input files: ------------------------- There may be several Doppler 1 X-Band files in level 1A which will be merged on level 2. The same is true for all other Doppler file type and Ranging X and S-Band files. Only files with continuous sequenced numbers (the file names are the same only the sequence number varies for these files) are merged together. Otherwise a new Level 02 data file is created (merging data files with a new sequence of files). The level 2 source_product_id however gives the RAW IFMS file names since the raw files are used for processing. But the content of the IFMS raw files are identical to the corresponding level 1A IFMS files in one data set, only the file name is different. And the source_product_id of the level 1A files gives the original raw IFMS files. In addition the level 1A files have almost the same file name as the corresponding level 2 files. The corresponding level 1A files can be found in DATA/LEVEL1A/CLOSED_LOOP/IFMS/DP1 for Doppler 1 files DATA/LEVEL1A/CLOSED_LOOP/IFMS/DP2 for Doppler 2 files DATA/LEVEL1A/CLOSED_LOOP/IFMS/RNG for Ranging files ---------------------------------------------------------Example: V32ICL1L02_D1X_053450236_00.TAB is a level 2 Doppler 1 X-Band file in V32ICL1L02_D1X_053450236_00.LBL the following SOURCE_PRODUCT_ID is given: SOURCE_PRODUCT_ID = {NN11_VEX1_2005_345_OP_D1_023612_0000, NN11_VEX1_2005_345_OP_D1_023612_0001, NN11_VEX1_2005_345_OP_D1_023612_0002} which are the raw IFMS files. The corresponding Level 1A files can be found in DATA/LEVEL1A/CLOSED_LOOP/IFMS/DP1 Their names are: V32ICL1L1A_D1X_053450236_00.RAW V32ICL1L1A_D1X_053450236_01.RAW V32ICL1L1A_D1X_053450236_02.RAW and the corresponding label files give the source_product_id as: in the V32ICL1L1A_D1X_053450236_00.LBL file the source_product_id is given as: SOURCE_PRODUCT_ID = NN11_VEX1_2005_345_OP_D1_023612_0000 in the V32ICL1L1A_D1X_053450236_01.LBL file the source_product_id is given as: SOURCE_PRODUCT_ID = NN11_VEX1_2005_345_OP_D1_023612_0001 in the V32ICL1L1A_D1X_053450236_02.LBL file the source_product_id is given as: SOURCE_PRODUCT_ID = NN11_VEX1_2005_345_OP_D1_023612_0002 Note that in this example the three level 1A files were merged to one level 2 files. The file names of the level 1A files are almost identical to the level 2 file name with three differences: - L1A instead of L02 in the file name which tells the user that these are level 1A and level 2 files. - The two digit-sequence number at the end of the file can be different. - The level 1A files have file extension .RAW whereas level 2 files have file extension .TAB ---------------------------------------------------------Other inputs for Doppler and Ranging files: ------------------------------------------- predicted orbit file (see EXTRAS/ANCILLARY/UNI_BW) Meteorological file (see CALIB/CLOSED_LOOP/IFMS/MET) AGC file (see DATA/1A or 1B/CLOSED_LOOP/AGC1 or AGC2) Spacecraft orbit SPICE kernels (see EXTRAS/ANCILLARY/SPICE can also be downloaded from ftp://ssols01.esac.esa.int/pub/data/SPICE/VEX/kernels) Calibration Documentation: -------------------------- For documentation about Doppler and Ranging Calibration please see in DOCUMENT/VRA_DOC/VEX-VRA-IGM-DS-3011 and VEX-VRA-IGM-DS-3012. For differential Doppler: ------------------------- If the processed level 2 file is for example Doppler 1 X-Band then information from IFMS raw Doppler 1 S-Band files which cover approximately the same time were used for processing as well. For Doppler 1 S-Band information from IFMS raw Doppler 1 X-Band files were used. Doppler 2 files were processed accordingly. In most cases on IFMS1 and IFMS2 X-Band data were recorded: The corresponding raw files names start with NN11_ or NN12_. S-Band data were in most cases recorded at IFMS3. The corresponding raw files names start with NN13_. If for some reason this configuration was changed this is indicated either at the beginning of this description or at the end in the anomaly report. For Ranging in addition are used: --------------------------------- Range calibration file (see CALIB/CLOSED_LOOP/IFMS/RCL) Klobuchar coefficients for Earth-Ionosphere calibration (can be downloaded from this site: http://www.aiub.unibe.ch/download/CODE/) The calibrated Doppler files contain observed IFMS sky frequency, X-band Doppler and S-band Doppler frequency shift, residual (computed using the predict file), and the differential Doppler. If only a single downlink frequency was used, a differen- tial Doppler cannot be computed and was set to -999.999999 in the output file. The level 2 ranging files contain the observed TWLT at X-band or S-band, the calibrated TWLT at X-band or S-band, the TWLT delay at X-band or S-band and the differential TWLT. If only one frequency was used, the differential TWLT is set to -99999.9. IFMS Level 2 output files: -------------------------- Level 2 IFMS data file (extension .TAB) Level 2 IFMS label file (extension .LBL) Level 2 IFMS log file (extension .LOG). The log files can be found in /EXTRAS/ANCILLARY/VRA/LOGFILES and contain information about the level 2 Doppler and Ranging data processing. ODF Level 2 input files: ------------------------ ODF Level 1B files Doppler and Range prediction file or Orbit reconstructed file Media calibration files The calibrated Doppler files contain observed IFMS Doppler expressed as X-band Doppler or S-band Doppler, residual and detrended X-band or S-band Doppler (computed using the predict file), the detrended differential Doppler. If only one single frequency was used, the differential Doppler will be set to -999.999999. The level 2 ranging file contains the observed Two-Way- Light-Time (TWLT) at X-band or S-band, the calibrated TWLT at X-band or S-band, the TWLT delay at X-band or S-band and the differential TWLT. If only one frequency was used, the differential TWLT is set to -99999.9. Other inputs for Doppler and Ranging files: ------------------------------------------- Predicted orbit file (see EXTRAS/ANCILLARY/UNI_BW) Meteorological file (see CALIB/CLOSED_LOOP/ODF/MET) Spacecraft orbit SPICE kernels (see EXTRAS/ANCILLARY/SPICE can also be downloaded from: ftp://ssols01.esac.esa.int/pub/data/SPICE/VEX/kernels) RSR Level 2 data: ----------------- There are four types of calibrated data in the data set; each is described briefly below. Surface Reflection Filter Files ------------------------------- SRF files contain power spectra derived from noise measure- ments when the radio system was stable and there were no spacecraft signals in the passband. SRFs were derived sepa- rately for each receiver channel; but the fact that the spectral characteristics of each receiver depended almost entirely on digital signal processing meant that there was little practical difference among channels when sampling rates (output bandwidths) were the same and the SRFs were interchangeable. SRFs were ASCII PDS SPECTRUM objects with attached labels. Level 2 Neutral Atmosphere Files -------------------------------- L2N files were the calibrated output of partial processing of RSR data collected for radio occultations. They were ASCII tables of frequencies and amplitudes in physically meaningful units. Separate L2N files were derived for each receiver channel. The Level 2 radio occultation data have been processed as follows: The RSR samples were digitally filtered to reduce bandwidth; in the process they were also converted from 16-bit I and 16-bit Q complex integer samples to 64-bit I and 64-bit Q double precision complex floating point samples. The complex floating point samples were Fourier transformed and estimates made of the carrier amplitude and frequency and their uncertainties. The reconstructed spacecraft trajectory, planetary epheme- redes, records of uplink and downlink tuning, and other data were used to calculate the expected carrier frequency at the receiving antenna. The Level 2 products are tables of the observed amplitude, its uncertainty, the observed frequency, its uncertainty, and the difference between the observed and the expected frequency as a function of time. Separate tables have been created for each RSR. Bistatic Radar Spectra ------------------------------ SPC files were the calibrated output of partial processing of RSR data collected for bistatic radar. They were ASCII tables of power and cross-voltage spectra. All spectra for a single observation were collected in a single ASCII file. The Level 2 bistatic radar spectra (BSR) have been processed as follows: The RSR samples were converted from 16-bit I and 16-bit Q complex integer samples to 64-bit I and 64-bit Q double precision complex floating point samples. In the process they were digitally corrected for non-uniform spectral response of the receiving system. This was done by computing spectra from series of time samples and dividing each spectrum by the square root of a power spectrum computed from many minutes of noise. The amplitude of the samples was then adjusted so that power spectra in each receiver channel would have an amplitude proportional to kTsysB where k is Boltzmanns constant, Tsys is the receiver system temperature in Kelvin, and B is the width of one frequency bin (spectral resolution) in the power spectrum. Then the power spectra (e.g., XR*conj(XR)) and cross spectra (e.g., XR*conj(XL)) were computed. Structure of CALIB Directory ============================ Please note that the following description lists all possible subfolders. If however there is no data to fill some of these folders they will not be generated. |-CALIB | |-CALINFO.TXT text description of the directory contents | | | |-CLOSED_LOOP | | |-DSN Closed-loop calibration data of the DSN ground | | | stations | | |-IFMS | | | |-RCL Range Calibration data files | | | |-DCL Doppler Calibration data files | | | |-MET Meteo data files | | | |-OPEN_LOOP | | |-DSN | | | |-BCAL System temperature calibration files | | | |-ION Ionospheric Calibration files | | | |-MET Meteo data files | | | |-TRO Tropospheric Calibration files | | | |-SRF Surface Reflection Filter Files | | | | | |-IFMS | | | |-RCL Range Calibration data files | | | |-DCL Doppler Calibration data files | | | |-MET Meteo data files | | | |-UPLINK_FREQ_CORRECT Folder includes files which indicate wrong and corrected uplink frequency and their corresponding files. Files in the CALIB Directory ---------------------------- Files in the CALIB directory are: Calibration data files have in principle the same structure as normal data files. But they do not contain scientific data but rather reflect the behaviour of the system. These kind of data is typically recorded at New Norcia once for every tracking before the real measurement took place. For example: range calibration data contain the equipment propagation delay measurements before the tracking pass. Note: If the uplink frequency in one of the .RAW files was identified as wrong the folder UPLINK_FREQ_CORRECT will be generated. It tells the user which files were affected and where to find the corrected Level 2 data files. Closed loop IFMS Calib data level 1A: ------------------------------------- These Level 1A data are incoming raw tracking data files obtained from ESA IFMS. All incoming data files will be renamed after the file naming convention format defined in section 5.1 of the VeRa File Naming Convention document VRAFNC2005 and get a minimal detached label file .LBL. The original file name of the incoming tracking data files will be stored in the according label file as SOURCE_PRODUCT_ID. These files have the file extension .RAW. Closed loop IFMS Calib data level 1B: ------------------------------------- IFMS Calib level 1B files are processed from level 1A (raw tracking data) into an edited ASCII formatted file. Three files are generated for each ESA IFMS Level 1A data file: Level 1B IFMS data file (extension .TAB) Level 1B IFMS configuration file (extension .CFG) Level 1B IFMS label file (extension .LBL) The label file contains the description of the .TAB as well as of the .CFG file. DSN METEO Files (MET directory) ------------------------------- DSN METEO files were produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. Files give weather calibration information for DSN complexes. These are ASCII files of variable length records. Each record is delimited by an ASCII line-feed (ASCII 10). METEO files were typically released weekly and contain all weather data for the complex since 1 January. Each METEO file is accompanied by a PDS label. The files grow at the rate of approximately 90 kB per month. DSN Ionosphere Calibration Files (ION Directory) ------------------------------------------------ Ionosphere Calibration files were produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They docu- mented and predicted Earth ionospheric conditions. Global Ionosphere Map (GIM) software created daily maps from Global Positioning System (GPS) data. Each day, a final map was created for the UT day three days previously and a preliminary map was created for the UT day immediately before. Also created were predict maps a couple times a week by averaging recent normal days. Then the software evaluated the maps at the spacecraft line-of-sight and fitted the results to a normalized polynomial versus time over each spacecraft pass. This was done for all three modes: final, preliminary, and predict. Then the software selected the best available cali- bration for each pass (in priority order final > preliminary > predict). An operator ran a plotting program to view all of the calibrations and overrode the default selections where desired. The mapping technique is described by MANNUCCIETAL1998. They are ASCII files of variable length records. Each record is delimited by an ASCII carriage-return line-feed pair (ASCII 13 followed by ASCII 10). ION files were usually released at one week intervals to cover a single month; only final files covering a full month are included in this archive. Each ION file is accompanied by a PDS minimal label. Typical file sizes are approximately 50 kB. Troposphere Calibration Files (TRO Directory) --------------------------------------------- Troposphere Calibration files were produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They docu- mented and predicted Earth tropospheric conditions and were based on measurements made using Global Positioning System (GPS) satellites. These are ASCII files of variable length records. Each record is delimited by an ASCII line-feed (ASCII 10). Surface Reflection Filter Files (SRF Directory) ----------------------------------------------- SRF files contain power spectra derived from noise measure- ments when the radio system was stable and there were no spacecraft signals in the passband. SRFs were derived sepa- rately for each receiver channel; but the fact that the spectral characteristics of each receiver depended almost entirely on digital signal processing meant that there was little practical difference among channels when sampling rates (output bandwidths) were the same and the SRFs were inter- changeable. SRFs were ASCII PDS SPECTRUM objects with attached labels. System Temperature Calibration Files (BCAL directory) ----------------------------------------------------- This table contains system temperature calibration results from Venus Express (VEX) bistatic radar experiments. For each receiver channel the table includes the best estimate of system temperature with the antenna pointed to zenith (either pre- or post-cal, or a combination of both), the associated noise diode temperature, and the system temperature at the mid-point of the bistatic (surface) observation. In general there is one set of four rows for each experiment one for each receiver channel (X-band and S-band, right- and left-circular polarization). The table is cumulative, growing by four rows for each new observation. The Bistatic Radar Calibration Log is produced by the Stanford University Element (SUE) of the Venus Express Radio Science Team under the direction of R.A. Simpson. Browse Files (BROWSE Directory) =============================== Browse files may be composite PostScript files summarizing quick-look processing of raw RSR data. In that case each file has a name: rggttttL1A_BRO_yydddhhmm_00.AUX. Each file has a JPEG version with the same file name but extension .LBL. Both files are accompanied by a single detached label of the same file name but extension .LBL. Each PostScript file is sized to fit on a single 8-1/2x11 inch page. Each landscape format page includes four panels showing a histogram of raw data (12-bit) samples (upper left), one-minute average power spectra derived from the raw samples (upper right), one-second averages of raw sample power versus time (lower left), and an extract of the first few lines of the source RSR PDS label (lower right). BRO files may be helpful in quickly scanning data to determine which files are suitable for closer study. IFMS Browse plot files are only available as JPEG files. These plots are generated in order to check data quality of IFMS Level 2 closed-loop data. The name of the files are the same like the Level 2 data files except for the data type identifier which is set as sss=B1X,B1S,B2X,B2S if the source of the plots is a Doppler 1 X-Band, Doppler 1 S-Band, Doppler 2 X-Band or Doppler 2 S-Band file, and the extension will be .JPG. Geometry information - Coordinate System ======================================== The geometry items SC_SUN_POSITION_VECTOR, SC_TARGET_POSITION_ VECTOR and SC_TARGET_VELOCITY_VECTOR provided in the label of the data products are calculated from the spacecraft to the sun center expressed in J2000 reference frame, corrected for light time and stellar abberation. SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE are given in the PLANETOCENTRIC coordinate system. These parameters are computed for the time given in POSITION_TIME. Distances are given in km, angles in degrees. More information can be found in the geometry_index file under INDEX/. Documentation is available in the VRA document folder. Ancillary Data ============== An extensive set of ancillary files is needed for proper analysis and interpretation of the radio data. These are organized in parallel directories and stored approximately chronologically. When a file type is not represented on a volume, the corresponding directory has been omitted. Files in the EXTRAS/ANCILLARY Directory --------------------------------------- Files in the EXTRAS/ANCILLARY directory are: ESOC: R^ant DDS files to describe the observation geometry SPICE: R^ant SPICE Kernels to describe the observation geo- metry UNI_BW: R^ant PREDICT files from the Uni BW Munich VRA: Level 2 processing log files SUE: Ancillary files coming from Stanford University |-SPICE: Spice Kernels were produced by the VEX Flight Dynamics Team, converted to IEEE binary format, and then distri- buted by the JPL Navigation and Ancillary Information Facility (NAIF). For more information on NAIF and SPICE see http://pds-naif.jpl.nasa.gov/ The original Spice Kernels were merged with the JPL DE405 planetary ephemeris and the ephemeredes of Phobos and Deimos for the same time interval. DSN: Ancillary files provided by Deep Space Network |-EOP: Earth Orientation Parameter Files | Earth Orientation Parameter files were produced by the | Time and Earth Motion Precision Observation (TEMPO) | Group at JPL. They documented and predicted Earth rota- | tion (rate and axis). These are ASCII files of variable | length records. Each record is delimited by an ASCII | line-feed (ASCII 10). | There are both long and short versions. The long | file covered past motion since about 1962 and a predic- | tion for about three months into the future; these files | have typical sizes of 1 MB. | The short file covered the most recent nine months of | past motion and a prediction for three months into the | future; these files are typically 30 kB. Each EOP file | is accompanied by a PDS minimal label. | |-OPT: Orbit Propagation and Timing Geometry File | Orbit Propagation and Time Generation files contain | estimates of event timing (e.g., equator crossings) that | depend on precise knowledge of the spacecraft orbit. | These are ASCII files of variable length records. Each | record is delimited by an ASCII carriage-return | (ASCII 13) line-feed (ASCII 10) pair. File names | have the form ydddeeeC.OPT where the file name compo- | nents are the same as for BCK files (above). | Each OPT file is accompanied by a PDS minimal label with | file name ydddeeeC.LBL. Typical files are based on | reconstructed spacecraft trajectories, cover a month of | operation, and have sizes less than 500 kB. | |-LIT: Light Time File | Light Time files give radio propagation time from the | spacecraft to Earth as a function of time. These are | ASCII files of fixed length records. Each record is | delimited by an ASCII carriage-return line-feed pair. | File names have the form ydddeeeC.LIT where the file | name components are the same as for DKF files. An LIT | file may cover more than 365 days; so eee may be a year | or more after yddd. Each LIT file is accompanied by a | PDS label. Typical file sizes are less than 1 MB. Software ======== Software for parsing, reducing, and analyzing data such as these has been developed at University of Cologne and Stanford University. Because such software must usually operate at the bit-level and is written for a narrow range of platforms, it is not suitable for general distribution. No software is included with this archival data set. Documents ========= The DOCUMENT directory contains the files that provide documen- tation and supplementary information to assist in understanding and using the data products on the volume. The files evolved as the mission progressed; users should refer to the files on the most recent (highest numbered) archive volume for the most up-to-date information. Files on early volumes may be only place-holders. The below mentioned documents represent the maximum of available documents, but need not to be present for every measurement. For IFMS (NNO) measurements, please refer mainly to VRA_DOC, for DSN measure- ments to DSN_DOC. Structure of the DOCUMENT directory: DOCUMENT | |- DOCINFO.TXT The file you are reading. |- VEX_POINTING_MODE_DESC.TXT VEX pointing mode | description |- OBSERVATION_TYPE_DESC.TXT VEX Observation types | |- VRA_DOC | | | |- M32ESOCL1B_RCL_021202_00.PDF Group delay stability | | .ASC specification and | | measurements at New Norcia. | | | |- M32ESOCL1B_RCL_030522_00.PDF Range calibrations at New | | .ASC Norcia and Kourou. | | | |- M32UNBWL1B_RCL_030801_00.PDF Transponder group veloci- | | .ASC ties (in German, .ASC in | | English). | | | |- VEX.VRA-IGM-IS-3007.PDF VeRa Data Archive Plan. | | VEX-VRA-IGM-IS-3007.ASC | | | |- VEX-VRA-IGM-IS-3009.PDF VRA File Naming Convention | | VEX-VRA-IGM-IS-3009.ASC | | | |- VEX-VRA-IGM-MA-3005.PDF VRA User Manual. | | | |- VEX_OPS_LOGBOOK_06.PDF Status of all planned | | radio science operations | | in year 2006 (later 07,08) | | | |- VEX-VRA-IGM-LI-3013.PDF List of VRA Team members. | | | |- VEX_VRA_IGM_DS_3011.PDF IFMS Doppler Processing and | | Calibration Software | | Documentation: Level 1A to | | Level 2. | | | |- VEX_VRA_IGM_DS_3012.PDF IFMS Ranging Processing and | | Calibration Software | | Documentation: Level 1A to | | Level 2. | | | |- VEX-VRA-IGM-DS-3014.PDF Radio Science Predicted | | and Reconstructed Orbit and | | Planetary Constellation | | Data: Specifications | | | |- VEX-VRA-UBW-TN-3040.PDF Reference Systems and Tech| | niques for Simulation and | | Prediction of atmospheric | | and ionospheric sounding | | measurements | | | |- VEX-VRA-IGM-DS-5007.PDF Radio Science Geometry and | | Position Index Software | | Design Specifications | | | |- VEX-VRA-IGM-DS-5008.PDF ODF Processing and Calibra| | tion Software: Level 1a to | | Level 1b Software Design | | Specifications | | | |- VEX-VRA-IGM-DS-5009.PDF ODF Doppler Processing and | | Calibration Software: Level | | 1b to Level 2 Software | | Design Specifications | | | |- VEX-VRA-IGM-DS-5010.PDF ODF Ranging Processing and | Calibration Software: Level | 1b to Level 2 Software | Design Specifications | |- ESA_DOC | | | |- IFMS-OCCFTP.PDF Documentation of IFMS data | | format. | | | |- VEX_ARCHIVE_CONVENTIONS.PDF Archive Conventions | | | | | |- VEX-ESC-IF-5003.PDF Data delivery interface | | document. | | | |- VEX-ESC-ID-5003_FDSICD.PDF File format description of | | ESOC Flight Dynamics files | | (ancillary files). | | | |- VEX-ESC-IF-5003_APPENDIX_C.PDF Documentation of DDS confi| | guration. | | | |- VEX-ESC-IF-5003_APPENDIX_I.PDF Definition of XML-schema | | for the data delivery | | interface. | | | |- VEX-ESC-IF-5003_APPENDIX_H.PDF Description of content of | | ESOC Flight Dynamics files | | (ancillary files). | | | |- VEX-RSSD-IF-0002.PDF Specifications of operatio| | nal interfaces and proce- | | dures | | | |- SOP-RSSD-TN-010.PDF Planetary Science Data | | Archive Technical Note Geo| | metry and Position Informa| | tion | | | |- VEX_ORIENTATION_DESC.TXT VEX Orientation description | | | |- VEX_POINTING_MODE_DESC.TXT VEX pointing mode descrip- | | tion | | | |- VEX_SCIENCE_CASE_ID_DESC.TXT VEX description of the | | science cases | | | |- PHASE 7.TAB VEX Mission subphases | | | |- OBSERVATION_TYPE_DESC.TXT VEX Observation types | | | |- VEX_MISSION_CALENDAR.PDF Description of the | | different phases of the | | mission. | | | | | |- VEX-EST-TN-036.PDF VEX Archive Conventions | | |- DSN_DOC | | | |-DSN_DESIGN_HB.PDF/.ASC | | Technical information and near future configurations of | | NASA Deep Space Network | | | |-DSN_ODF_TRK-2-18.PDF | | Documentation of Tracking System Interfaces and Orbit Data | | File Interface | | | |-JPL_D-16765_RSR.PDF | | Documentation of RSR data format | | | |-LIT_SIS.HTM | | Software Interface Specification: Light Time File | | | |-V00DSN0L1A_DKF_yydddhhmm_vv.TXT (optional) | | DSN Keyword File derived from SOE file and models of | | activities supported by the DSN | | | |-V00DSN0L1A_SOE_yydddhhmm_vv.TXT (optional) | | Sequence of Events file | | | |-VggDSN0L1A_NMC__yydddhhmm_vv.TXT (optional) | | Network Monitor and Control Logfile | | | |-V43SUE0L1A_MFT__yydddhhmm_vv.TXT (optional) | | Venus Express Manifest file | | | |-MEDIASIS.HTM | | Media Calibration data: formats and contents | | | |-MON0158.ASC/.DOC/.PDF (optional) | | Definition of format and distribution of the real-time, | | mission monitor data | | | |-NMC_SIS.TXT | | Contents of Network Monitor and Control Log. | | | |-OPTG_SIS.TXT | | Software Interface Specification for the Orbit Propagation | | and Timing Geometry (OPTG) file. | | | |-Ryddd.ASC/.DOC/.PDF (optional) | | Set of notes describing tests before and during radio | | science tests or operations or the progress of an | | experiment itself. y represents the year, ddd the DOY. | | | |-JPEG | | Zip-folder with 4 sets of 24 jpeg-files, each from a | | different receiver, showing circularly polarized received | | power spectra averaged over 60 seconds. FILENAME: | | Rydddbca.jpg with y:year, ddd:doy, b:X- or S-band, c: Left | | or Right-Hand circulation, a:alphabetic numbering for each | | plot of 60s. | | | |-SRX.TXT (optional) | | Software Interface Specification for Surface Reflection | | investigation files. | | | |-TNF_SIS.TXT | | Deep Space Mission System External Interface Specification | | | |-TRK_2_21.TXT | | Software Interface Specification | | | |-TRK_2_23.TXT / DSN_MEDIA_CAL_TRK_2_23.PDF | | Specification of DSN media calibration data. | | | |-TRK_2_24.TXT / DSN_WEA_FORMAT_TRK_2_24.PDF | | Specification of DSN weather file. The documents are either in PDF-Format or are text files in ASCII with variable length of characters per line. Each line is delimited with a carriage-return (ASCII 13) line-feed (ASCII 10) pair. Media/Format ============ The archival data set is written on CD-WO media using the WinOn CD Creation Software or Nero Burning Rom. The CD-WO volumes conform to ISO 9660 standards. More general description of radio science data ============================================== Closed-loop and Open-loop data: ================================ There are in principle two different ways to record radio science data: Open-loop and closed-loop data. The CLOSED-LOOP system used a phase-lock loop in the receiver to track the downlink signal, reporting both amplitude and fre- quency at rates typically of 1-10 times per second. In the OPEN-LOOP system, the signal was simply converted to a baseband frequency range; the entire passband was sampled and recorded for later processing. Typical open-loop sampling rates for VEX were 100000 complex samples per second. CLOSED-LOOP data are efficient for characterizing slowly changing signals; OPEN-LOOP data (because of their much higher volume) are usually used when the signal is very dynamic - such as during an occultation or bistatic radar measurement. The data set includes four primary data types with respect to the two different ground station systems. These systems are on the one hand the ESA ground station in New Norcia, Australia (NNO) and the NASA Deep Space Network (DSN). CLOSED-LOOP data types: | |- ESA: Intermediate Frequency Modulation System (IFMS) | Closed-Loop (CL) | | In this data set file names of data recorded at the | New Norcia IFMS closed loop system start with the | string V32_ICL for Level 2. | | IFMS CL consists of Doppler and Ranging data at | selected sample rates. The sample rate is usually | 1/s. | The only exception are occultation data where the | sample rate should be 10/s to get a good enough | vertical resolution of the atmosphere. | Ranging are only recorded for gravity measurements. | | Thus the IFMS closed loop has three recording | systems IFMS 1, IFMS 2 and IFMS 3 | The standard_data_product_id in the data label | specifies on which system the data was recorded. | | VeRa measurements are usually done in TWO-WAY | configuration: that is an uplink signal goes up | (this is usually X-Band but the uplink signal can | also be S-Band) and the ground station receives a | dual frequency simultaneous and coherent downlink | signal. | | IFMS 1 is configured for the uplink signal. It | receives X-Band downlink if uplink was X-Band and | S-Band downlink if uplink was S-Band. | IFMS 2 acts as backup. | IFMS 3 records the second downlink signal. This is | usually S-Band. But can also be X-Band when the | uplink was S-Band. | | IFMS 1 D1 is fixed to a sample rate of 1/s | IFMS 1 D2 is on fixed to a sample rate of 1/10s | | In addition each Doppler recording system has also | two Doppler channels which can record simultaneous| ly and act as an additional backup system. | Therefore for each IFMS system there should be at a | given time two Doppler files and two Auto Gain | Control files recorded. The file names of these | data contain the string _D1 or _D2 for Doppler | and _G1 or _G2 for Auto Gain control files and | they will be on different subfolders within the | data directory. See further down the description of | the DATA Directory. | | For these data files only X-Band ranging was | possible. Ranging data was nominally recorded on | IFMS1. | |- DSN: |-Tracking and Navigation File (TNF) | | The Tracking and Navigation File (TNF) is the primary out| put from the DSN closed-loop receiver system. These are | large files, accumulating at the rate of approximately 3 | megabytes (MB) per hour of antenna operation. The files | comprise nearly 20 block types, each designed to carry | data of interest to a particular navigation, telecommuni- | cations, or science community. | The blocks are described by TNF_SIS.TXT in the | DOCUMENT/DSN_DOC directory. Fields include: | Uplink and downlink antenna numbers | Spacecraft number | Equipment identifiers, status flags, and calibration | values | Time tags and frequency bands | Transmitted and received phase and frequency | Transmitted and received ranging information | Noise levels, signal-to-noise ratios, and uncertain- | ties | |-Orbit Data Files (ODF) | | For many applications the TNF is too cumbersome. The ODF | is an edited and partially processed version of the TNF. | It is a smaller file, often issued in daily increments of | about 0.2 MB. It contains the most important information | (range and Doppler) needed by spacecraft navigators and | investigators interested in determining gravitational | fields of bodies such as Mars. | Each ODF is accompanied by a full PDS label which | describes both the content and format of the associated | file. ODF data fields include: | Narrowband spacecraft VLBI, Doppler mode (cycles) | Narrowband spacecraft VLBI, phase mode (cycles) | Narrowband quasar VLBI, Doppler mode (cycles) | Narrowband quasar VLBI, phase mode (cycles) | Wideband spacecraft VLBI (nanoseconds) | Wideband quasar VLBI (nanoseconds) | One-way Doppler (Hertz) | Two-way Doppler (Hertz) | Three-way Doppler (Hertz) | One-way total count phase (cycles) | Two-way total count phase (cycles) | Three-way total count phase (cycles) | PRA planetary operational discrete spectrum range (range | units) | SRA planetary operational discrete spectrum range (range | units) | RE(GSTDN) range (nanoseconds) | Azimuth angle (degrees) | Elevation angle (degrees) | Hour angle (degrees) | Declination angle (degrees) | | For more information please refer to document | DSN_ODF_TRK-2-18 in the DOCUMENT/DSN_DOC folder. Open- Loop data types: | |-ESA: Intermediate Frequency Modulation System (IFMS) Open-Loop | (OL) | | In this data set file names of data recorded at the | New Norcia IFMS open loop system start with the | string V32_IOL for Level 2. | | IFMS OL consists of Doppler data at selected | sample rates. The sample rate is usually | 100000 samples per second. | | The IFMS open loop has three recording systems | IFMS 1, IFMS 2 and IFMS 3, whereas the Doppler | channel 1 (D1) of the IFMS 2 and 3 (NN12 and NN13 | in the original filenames) receives open loop data. | The other channels are configured as described in | the closed loop section. | The standard_data_product_id in the data label | specifies on which system the data was recorded. | | VeRa open loop measurements are usually done in | ONE-WAY configuration: that is the spacecraft | sends and the ground station receives a dual | frequency simultaneous and coherent downlink | signal. IFMS 2 D1 receives usually X-band, IFMS 3 | D1 usually S-band. Sometimes the configuration was | such that both channels received X-band. | | Open-loop measurements come from the GDSP 17.5 Msps | 24-bit complex base band stream (containing 1, 2, | 4 or 12 bit words each for the I and Q channels) | and result from filtering and decimating the | 280 Msps 8-bit stream output by the Common Front | End (CFE) Analogue to Digital converter. These | channels are provided for both RHC and LHC | polarizations. | | The Open-Loop data-sets contain: | First data-set (sequence Id=0000): standard header | and active configuration in ASCII. | Following data-sets (sequence Id >=0001): fixed- | length binary records containing each a header (76 | bytes: record length, sampling frequency, samples | quantization, time stamp of first sample, LO Fre- | quency off-set of single channels, LO Frequency | sweep rate), and data (1392 bytes, 87 complex | samples); a new data-set is open every minute. | Each complex sample consists of 16 bits in phase | sample (real part) for each channel, and 16 bits | qudrature sample (imaginary part) for each channel. | There are four channels, but actually channel 1 and | 2 are used for Radio Science open-loop data. | | The binary open-loop datasets are formatted by the | IFMS and transported to the ESU (External Storage | Unit) via the IFMS Ethernet network ports. | | |-DSN: Radio Science Receiver (RSR) | | The Radio Science Receiver (RSR) is a computer- | controlled open loop receiver that digitally records a | spacecraft signal through the use of an analog to | digital converter (ADC) and up to four digital filter | sub-channels. The digital samples from each | sub-channel are stored to disk in one second records | in real time. In near real time the one second records | are partitioned and formatted into a sequence of RSR | Standard Format Data Units (SFDUs) which are | transmitted to the Advanced Multi-Mission Operations | System (AMMOS) at the Jet Propulsion Laboratory (JPL). | Included in each RSR SFDU are the ancillary data | necessary to reconstruct the signal represented by the | recorded data samples. | | Each SFDU is defined here as a single row in a | PDS TABLE object; later SFDUs are later rows. The | first fields in each row contain the ancillary data | (time tags and frequency estimates, for example) that | applied while the samples at the end of the record | were being collected. The object definitions below | explain where the fields are and what the contents | represent. | | Analysis of variations in the amplitude, frequency, | and phase of the recorded signals provides information | on the ring structure, atmospheric density, magnetic | field, and charged particle environment of planets | which occult the spacecraft. Variations in the | recorded signal can also be used for detection of | gravitational waves. | | DSN open-loop receivers sample a narrow part of the micro| wave spectrum near the spacecraft transmitting frequency. | For radio occultation tests, two RSRs were used - one | each for X-RCP and S-RCP with output sampled at rates of | 2000 (complex; 16-bit I, 16-bit Q). | The data were examined for compliance with data acquisi- | tion procedures and to measure the frequency/stability of | the radiolink. Four RSRs (X-RCP, S-RCP, X-LCP, and S-LCP) | each sample at a rate of 25000 (complex; 16-bit I, | 16-bit Q) to test bistatic radar data acquisition. | | Header information accompanying each RSR record included: | | Date and time of the first data sample | Sample rate and channel assignments | Receiver local oscillator phase and frequency | Attenuator settings | RMS voltages at several stages in the receiving chain | | | For more information please refer to document | JPL_D-16765_RSR in the DOCUMENT/DSN_DOC folder.
Instrument
VRA
Temporal Coverage
2007-06-03T00:00:00Z/2007-06-03T00:00:00Z
Version
V1.0
Mission Description
Mission Overview ================ Venus Express is ESAs first mission to Venus. It reuses the design of the Mars Express spacecraft. Many of the instruments are simply upgraded versions of those developed for ESAs Mars Express and Rosetta missions. The scientific objectives of the mission is to study the atmosphere, the plasma environment, and the surface of Venus in great detail. Venus Express was launched by a Soyuz-Fregat launcher from the Baikonour Cosmodrome on 9 November 2005. After separation, Venus Express, of mass 1244 kg, was placed into an interplanetary transfer orbit during approximately 150 days. After a 153 day cruise to Venus the spacecraft entered Venusian orbit on 11 april 2006. The first capture orbit was an eccentric polar and lasted 9 days. Several manoeuvres over the period 15 April-6 May 2006 lowered the spacecraft into its operational orbit: a 24-hour elliptical, quasi-polar orbit. The pericentre altitude is 250 kms and the apocentre altitude is 66000 kms. Pericentre altitude 250 km Apocentre altitude 66000 km Period 24 h Inclination ~90 deg Pericentre latitude 80 deg The mission has been described in many papers ESABUL2005; HUNTER2004. Details about the mission launch sequence and timeline can be obtained from the Mission Calendar VEX-ESC-TN-5002 and from the Consolidated Report on Mission Analysis (CREMA)VEX-ESC-RP-5500. Mission Phases ============== The mission timeline defines the different spacecraft and payload operations required per phase to prepare the spacecraft for Venus operational orbit acquisition, science data acquisition and transmission. Six nominal mission phases plus the pre-launch phase are defined for achieving the scientific mission objectives. They are detailed below. PRELAUNCH --------- Pre-launch operations started approximately 6 months before the launch and covered the period from delivery of the spacecraft to the launch site until L-8 hrs in the launch countdown sequence. During this period the Venus Express Mission Operations Centre (VMOC) at ESOC performs its final simulation programme including the validation of the Flight Operations Plan (FOP) and the final mission control system. mission phase start time : UNK mission phase stop time : 2005-11-09 LAUNCH AND EARLY ORBIT PHASE (LEOP) ----------------------------------- The Venus Express spacecraft was launched on a Soyouz-Fregat rocket from the Baikonur Cosmodrome at 3:33:34 UT on 9 November 2005. The three-stage Soyuz launcher lifted the Fregat autonomous upper stage (fourth stage) with Venus Express mounted on it into a sub-orbital trajectory. After separation from the Soyuz third stage, a Fregat main engine burn (at an altitude of about 200 kilometres) for around 20 seconds placed the Fregat-Venus Express composite into an almost circular parking orbit. After a coast phase of about 70 minutes in the low Earth orbit, a second Fregat engine burn, lasting 16 minutes, moved the combined craft from the parking orbit onto an escape trajectory, after which the Fregat stage and Venus Express separated. Duration : 3 days mission phase start time : 2005-11-09 mission phase stop time : 2005-11-11 After separation, Venus Express spent approximately 150 days in an interplanetary transfer orbit. During this phase, trajectory corrections were performed using the spacecrafts own thrusters. NEAR EARTH COMMISSIONING PHASE (NECP) ------------------------------------- It includes the following activities for the spacecraft: - spacecraft commissioning. - deployment of the MAG Boom. - Payloads commissioning. Duration : 3 weeks mission phase start time : 2005-11-12 mission phase stop time : 2005-12-16 INTERPLANETARY CRUISE PHASE --------------------------- The Interplanetary Cruise Phase finishes about one month before Venus capture. During this 3 months phase, the spacecraft in on the Sun-centred ballistic orbit to Venus. Most of this phase is not dedicated to any specific activity, except the cruise orbit determination and correction. Duration : 107 days mission phase start time : 2005-12-17 mission phase stop time : 2006-04-04 VENUS ORBIT INSERTION PHASE (VOI) --------------------------- The Venus Orbit Insertion (VOI) phase is the period of transition between the Interplanetary Cruise phase and the final operational orbit around Venus. It starts before the Venus capture manoeuvre and ends when the satellite has reached the operational orbit. The duration of this phase is about 2 weeks. A final course adjustment was performed on 29 March to fine tune the arrival hyperbola for Venus Orbit Insertion. The VOI manoeuvre took place on 11 April 2006. To enable capture of the spacecraft, it was first slewed such that the main engine was aligned to the direction of travel. The main engine burn lasted around 50 minutes and decelerated the spacecraft by approximately 1251 ms-1 (~ 4500 kmh-1). The spacecraft initially entered a highly elliptical polar orbit with a pericentre of 400 km, an apocentre of 350 000 km and a period of 9 days. To achieve the final operational orbit a series of correction manoeuvres are necessary: Date Activity Velocity Change (m/s) 15 April 2006 Pericentre Control Manoeuvre #1 5.8 20 April 2006 Apocentre Lowering Manoeuvre #1 199.9 23 April 2006 Apocentre Lowering Manoeuvre #2 105.3 26 April 2006 Apocentre Lowering Manoeuvre #3 9.2 29 April 2006 Apocentre Lowering Manoeuvre #4 8.0 2 May 2006 Apocentre Trim 2.0 6 May 2006 Pericentre Control Manoeuvre #2 3.1 Duration : 16 days mission phase start time : 2006-04-05 venus capture manoeuvre : 2006-04-11 mission phase stop time : 2006-04-21 VENUS ORBIT COMMISSIONING PHASE --------------------------------- The Venus Payload Commissioning phase starts when the spacecraft has reached the operational orbit and ends when it is declared ready for science data acquisition and transmission to the Earth. It is dedicated to spacecraft commissioning activities, payloads commissioning and demonstration activities prior to operational science operations. The duration of the Payload Commissioning phase around Venus is about 1 month. The operations to be performed during the phase are the following: - S/C in-orbit commissioning, - Payloads in-orbit commissioning, - Isolation of the Propulsion system. Duration : 42 days mission phase start time : 2006-04-22 mission phase stop time : 2006-06-03 ROUTINE OPERATIONS PHASE ------------------------ The selected operational orbit is inertially fixed, so that coverage of all planetocentric longitudes will be accomplished in one Venus sidereal day (243 Earth days). The nominal mission orbital lifetime is two Venus sidereal days (486 Earth days). It consists in science data acquisition from the payloads, data storage in the SSMM and data transmission to the Earth. There are two different phases of operations for Venus Express once it is in operational orbit: the Earth Pointing phase and the Observation phase. The Earth pointing phase is dedicated to communication with Earth and battery charging. It is used whenever the spacecraft is not in the observation phase. In the Earth pointing phase, one of the two High Gain Antennas is oriented towards Earth. The antenna is selected according to the season, so that the spacecrafts cold face remains always protected from illumination by the Sun. The rotation angle around the Earth direction is optimised in order to avoid any entrance of Sun light on the side walls radiators. High rate communication will be performed 8 hours per day in X-band, in order to transmit to Earth all science data stored in the Solid State Mass Memory. An average of 2 Gbits of science data will be downlinked every day to the new ESA ground station of Cebreros, Spain. The observation phase consists of several different modes of observation, depending on the payload configuration and spacecraft orientation: Nadir pointing, Limb observation, Star occultation, Radio science. During observation, the Sun can illuminate under transient conditions any spacecraft face, except for the cold face. The duration of observation is therefore limited by thermal constraints and by battery discharge. The maximum duration of an observation period depends on the Sun direction with respect to the orbit plane, which varies along the mission. Observations and spacecraft activities are planned based on the following principles: 1. Complete and uniform the coverage of the science themes 2. Balance between distant and close-up view of Venus 3. Balance between observations of the Northern and Southern hemisphere 4. Synergy between experiments in covering science objectives 5. Use of two cases in each orbit: one in apocentre, one in pericentre 6. Even distribution of pericentric cases with priority given to the solar and Earth radio occultation experiments in speific seasons 7. Apocentric cases (2,3) are grouped in campaigns of 10 orbits that is required by the atmospheric dynamics mission objectives 8. Maximum compliance with the current flight rules. Individual Objectives per Instrument -----------------------------------ASPERA On during the entire mission and permanently collecting data. Survey observations in the beginning of the mission and more specific and detailed observations on selected part of the orbit later in the mission. Data is collected at different rates depending on the selected mode. MAG On during the entire mission and permanently collecting data. Data is collected at different rates depending on the selected mode. SPICAV The main goal of SPICAV is to sound the Venus atmosphere in solar and stellar occultation geometry with sufficient latitude and local time coverage. SPICAV does also nadir and corona observations (90 deg slew from nadir pointing and back to nadir). VeRa 4 types of observations 1. Earth occultation with as good as possible latitude and local time coverage of Venus. 2. Bi-static sounding of surface targets. The radio signal is sent to selected targets on the Venus surface. Reflected and scattered signal is received by ground station. As the signal is weak, the experiment depends on the Earth Venus distance, geometry and surface target properties. 3. Solar Corona observations in vincinity of conjunctions. 4. Gravity anomaly. It consists in the precise tracking of the s/c while it passes over global geological formations on Venus solid body. It has been carried out only twice during the nominal mission . Duration : 486 days mission phase start time : 2006-06-04 mission phase stop time : 2007-10-02 EXTENDED OPERATIONS PHASE ------------------------- The nominal mission ended on October 2, 2007 when started the first extended mission. The first extended mission phase was approved until May 2009. The first extended mission has the following objectives: - Improve and complete spatial and temporal observational coverage - Study in detail the phenomena discovered in the nominal mission - Take advantage of the new operation modes (case #2 pendulum, spot pointing, ...) - Perform percentre lowering down to the altitude that still allows usual operations without entering aerobraking mode (around 170-270 km) - Perform necessary studies and tests preparing te spacecraft for future aerobraking campaign These goals determine the following planning outline for the extended mission: - October 3, 2007 - May 31, 2008 (MTP 19-27): like nominal mission - June 2008 - TBD operations with low pericentre. - TBD: Aerobraking campaign. Pericentre lowering campaign: The pericentre altitude was maintained between 250 km and 350 km during the first 8 months of the extended mission. After May 31, 2008 the pericentre was lowered to the corridor 170-220 km. This pericentre lowering aimed at observing plasma at this altitude range. The apocentre and the pericentre latitude hasnt changed (66000 km, about 78 deg). Science Subphase ---------------- For the purpose of structuring further the payload operations planning, the mission phases are further divided into science subphases. Phase number Date Orbit CRUISE 2005-11-09 -1 VOI 2006-04-11 0 PHASE 0 2006-05-14 23 PHASE 1 2006-06-04 44 PHASE 2 2006-07-11 82 PHASE 3 2006-09-14 146 PHASE 4 2006-11-16 209 PHASE 5 2007-02-01 286 PHASE 6 2007-03-16 330 PHASE 7 2007-04-25 370 PHASE 8 2007-06-30 436 PHASE 9 2007-08-21 488 PHASE 10 2007-10-04 531 PHASE 11 2007-10-27 554 PHASE 12 2008-01-04 623 PHASE 13 2008-04-01 711 PHASE 14 2008-06-05 776 PHASE 15 2008-08-01 833 PHASE 16 2008-09-23 886 PHASE 17 2008-12-31 985 PHASE 18 2009-03-02 1046 PHASE 19 2009-05-05 1110 PHASE 20 2009-06-24 1160 PHASE 21 2009-09-20 1248 PHASE 22 2009-10-18 1276 PHASE 23 2009-12-17 1336 PHASE 24 2010-02-02 1383 PHASE 25 2010-04-07 1447 PHASE 26 2010-05-30 1500 PHASE 27 2010-07-12 1543 VOI and Phase 0 ------- This initial phase is devoted to the spacecraft and payload checkout and in orbit commissioning. The phase will consist of: - experiments commissioning (until 14 May 2006, orb 23). - Science case commissioning (16-27 May 2006, Orb 23-36). - Extended case commissioning (May 28-June 3, Orb 37-43). The ECC will also occupy the first half of phase 1. The phase contains the first eclipse season that ends at orbit 40. VOI --- Dates : April 11 - May 13 2006 Orbits : 1 - 23 Phase 0 ------- Dates : May 14 - June 03, 2006 Orbits : 23 - 43 Phase duration : 20 days MTP : 1 Phase 1 ------- Phase 1 is favorable for observations of the evening terminator vicinity. In particular, the following observation are performed: - Cloud observations; - lightning on the night side; - stellar occultation on the dark limb (north/south asymmetry of the aerosol vertical structure); - Solar occultation (horizontal structure of hazes above the main cloud deck); - Thermal mapping of Ishtar Terra and Maxwell Montes; - Limb observations (vertical structure of haze layers); - Observations of nightglows (O2, NO ...), their latitude and vertical variability; - Bistatic sounding of the Maxwell Montes (BSR#1) - Comet Mrkos by SPICAV and VMC on June 5, 2006. SPICAV observe nadir and stellar occultations. VeRa perform bi-static sounding (BSR#1) of Maxwell Montes. VIRTIS observe the evening sector of the planet, night side mosaics, thermal mapping of Maxwell Montes and limbs. VMC observe the evening sector of Venus, limbs and perform thermal mapping of Maxwell Montes. Dates : June 4 - July 10, 2006 Orbits : 44-81 Phase duration : 37 days MTP : 2-3 Phase 2 ------- Phase 2 starts at the beginning of the first Earth occultation season in orbit 81 and ends at the end of the 2nd eclipse season in orbit 145. It provides favorable conditions for nadir observations of the night side. The following observations have the priority: - Solar occultations; - Earth radio-occultations; - Night side dynamics with high spatial resolution - Twilight limb observations in forward scattering geometry - Nightglow observations - Thernal mapping of the surface The night side surface targets are Beta Regio, Theia Mons, Phoebe Regio, Ishtar Terra (Lakshmi Planum). ASPERA take measurement of the night side plasma. SPICAV observe in nadir mode and the solar occultations. VeRa observe during the Earth occultation season #1 and participate in the gravity campaign #1. VMC observe the night side: atmopsheric dynamic, night side surface mapping of the targets listed above. They observe also nightglow and they search for lighting. Dates : July 11 - September 13 2006 Orbits : 81 - 145 Phase duration : 64 days MTP : 3-5 Phase 3 ------- The Venus dark side could be observed in the beginning of Phase 3. Phase 3 will also have conditions for systematic observations of the morning/evening terminator and for solar corona studies. The phase contains the first superior solar conjunction (orbit 179-201). The following observations are performed: - Cloud at terminator (study of cloud and haze structure); - Coordinated campaign of atmospheric dynamics observations in Northern and Southern polar regions; - Search for lighting on the night side; - Double stellar occultation on the dark limb (north-south assymetry of aerosol vertical structure); Mapping of surface targets (Isthar Terra); - Limbs (vertical structure of haze layers); - Nightglows (O2, NO...): latitude and vertical variability; - Solar Corona studies; - Gravity anomaly #1 ASPERA observe the morning sector. SPICAV observe nadir and stellar occultations. VeRa observes the Solar Corona and do the 1st gravity anomaly campaign. VIRTIS observe the north/south polar dynamics, the Ishtar Terra night side target and the morning sector. VMC observe the north/south polar dynamics, the Ishtar Terra night side target, the high-resolution atmospheric dynamics and the nightglow and search for lightning. Dates : September 14, 2006 - November 15, 2006 Orbits : 146 - 208 Phase duration : 62 days MTP : 5-7 Phase 4 ------- Phase 4 starts at the beginning of the eclipse season in orbit 209 and ends at the end of the Earth occultation season in orbit 285. ASPERA observe in details the nightside plasma. SPICAV observe solar occultations and in nadir mode. VeRa observe during Earth occultation season and Solar Corona. VIRTIS and VMC observe on the dayside but also nightside of Theia Mons and Lakshmi Planum. Dates : November 16, 2006 - January 31, 2007. Orbits : 209 - 285 Phase duration : 76 days MTP : 7-10 Phase 5 ------- Phase 5 starts at the end of the Earth occultation season #2 and ends at the beginning of the eclipse season #4. It has favorable conditions for observations of the evening terminator. Focus is also made on the night side. The following observations are performed: - Cloud observations at terminator (study of cloud and haze structure); - North-South atmospheric dynamics; - Search for lightning on the night side; - Double stellar occultation on the dark limb (north-south assymetry of aerosol vertical structure); - Mapping of surface targets: Atla Regio, Ozza Mons; - Limbs (vertical structure of haze layers); - Nightglows (O2, NO...): latitude and vertical variability; ASPERA observe in details the evening sector. SPICAV observe nadir and stellar occultation. VeRa do not observe anything. VIRTIS and VMC do mosaic and off pericentre observations. They participate in the North/South pole dynamics campaign. They also observe the night side. Dates : February 1 - March 15, 2007. Orbits : 286 - 329 Phase duration : 43 days MTP : 10-12 Phase 6 ------- Phase 6 starts at the beginning of the eclipse season #4 in orbit 330. It ends with the same season in orbit 369. The phase provides good conditions for observations of the night side and atmospheric sounding in solar occultation geometry. Solar occultations are used to study composition and structure of the atmosphere above the cloud top. Campaigns of off-pericentre observations and apocentre VIRTIS mosaic are used to study composition and dynamics of deep atmosphere on the night side. Conditions will be also favourable for observations of nightglows to study composition and dynamics of the thermosphere and search for lightning. Limb observations in forward scattering geometry (spacecraft in eclipse) will provide good opportunity to study vertical structure of hazes above the main cloud. Thermal mapping of the surface and search for active volcanism is performed. One bi-static sounding experiment (BSR #4) is scheduled. The night side surface targets are Beta Regio, Theia Mons and Phoebe Regio. SPICAV observe nadir and Solar occultations. VeRa do the bi-static sounding experiment #4. VIRTIS and VMC observe off-pericentre and in mosaic mode. They observe Themis and Phoebe Regio on the night side. Dates : March 16 - April 24, 2007. Orbits : 330 - 369 Phase duration : 39 days MTP : 12-13 Phase 7 ------- Phase 7 starts with the Earth occultation season #3 in orbit 370 and ends with it in orbit 435. Proximity to the Earth creates excellent conditions for bi-static sounding and radio-occultation experiment that can reach maximum sounding depth. It is used to study the atmosphere with high spatial resolution. As earlier in phases 1, 3, 5 the terminator sector of the planet is available for observations in this phase. Cloud structure and atmospheric dynamics are important goals. The night side surface targets are Gula and Sif Mons, Guinevere Planitia, Ishtar Terra, Atalanta Planitia, Atla Regio and Ozza. SPICAV observe nadir and stellar occultations. VeRa is on during the radio occultation season 4 and perform the bi-static radar experiment #5 (Ozza Mons). VIRTIS and VMC do off-pericentre and mosaic observations. They observe Ishtar Terra and Maxwell Montes on the night side. Dates : April 25 - June 29, 2007. Orbits : 370 - 435 Phase duration : 65 days MTP :13-15 Phase 8 ------- Phase 8 starts and ends with the eclipse season #5 (orbit 436-487). Thus significant portion of orbits will be devoted to solar occultation observations. This phase is favourable for investigation of dayside dynamics. Proximity to the Earth provides good conditions for solar corona studies and bi-static sounding. Gravity #2 target is Atalanta Planitia, which was poorly covered by the Magellan observations. The thermal mapping covers Beta Regio, Phoebe Regio. SPICAV observe nadir and solar occultation. VeRa do the gravity #2 experiment and bi-static radar sounding #6 (Beta Regio and Theia Mons). VIRTIS and VMC do off-pericentre and mosaic observations of the dayside. Dates : June 30 - August 20, 2007. Orbits : 436 - 487 Phase duration : 51 days MTP : 16-17 Phase 9 ------- Phase 9 contains the Earth occultation season #4. It is favourable for observations of the vicinity of evening terminator. By the end of this season conditions for the off-pericentre night side observations is fulfilled. Main scientific focus of this phase is to provide observations of the evening terminator. The following observations are carried out: - Cloud observations at terminator (study of cloud and haze structure); - Search for lightning on the night side; - Double stellar occultation on the dark limb (north/south asymmetry of the aerosol vertical structure); - Grazing solar occultation (horizontal structure of the hazes above the main cloud deck); - Mapping of the surface targets; - Limb (vertical structure of haze layers); - Nightglows (O2, NO) and their latitude and vertical variability. The night side surface targets are Atalanta Planitia, coronae, Guinevere Planitia and Ishtar Terra. SPICAV observe nadir and stellar occultation. VeRa do the bi-static radar sounding #6a. VIRTIS and VMC observe the morning and evening sectors. Dates : August 21 - October 3, 2007. Orbits : 488 - 530 Phase duration : 42 days MTP : 17-19 Phase 10 -------- Phase 10 has no eclipse or occultation seasons. A routine sequence of off-pericentre observations followed by Nadir, limb or stellar occultations are carried out. The night side surface targets are Atla Regio (Sapas, Maat, Ozza Mons), Zemina corona. SPICAV SOIR does not make any observation during this phase (no occultations). Dates : October 4 - October 26, 2007. Orbits : 531 - 553 Phase duration : 22 days MTP : 19-20 Phase 11 -------- Phase 11 starts with the eclipse season #6 in orbit 554. However, solar occultations is only possible from orbit 576 to 596 because of the temperature conditions due to the sun position. VIRTIS perform some airglow campaign in nadir and limb geometry. VMC observe the surface on the night side. The observation targets are Asteria Regio, Hinemoa, Gunda and Kawelu Planitia, Beta Regio (Rheja and Theja Mons) and Phoebe Regio. SPICAV will observe stars at large distance, later in the phase. Two spot pointings are performed in orbit 561 and 571 (study of cloud scattering phase function). Gravity measurements are performed over Atalanta Planita in orbits 615, 617, 619, 621. Meteors occur in orbit 555. Despite the solar occultation that begins 27th October 2007, SOIR does not make any observation neither calibration until 25th November 2007, due to thermal reasons in Quadrature period. Dates : October 27, 2007- January 3, 2008. Orbits : 554 - 622 Phase duration : 68 days MTP : 20-22 Phase 12 -------- Phase 12 starts with Earth occultation season # 5 and ends with the eclipse season # 7. Earth occultation season begins in orbit 623 and ends in orbit 692. Pendulum observations are performed during all this phase. From orbit 659 to orbit 680, three periods overlap: Earth occultations, Eclipse season, solar opposition. The solar opposition is favorable for apocentre mosaics by VIRTIS. The surface targets for this phase are Atahensik and Zimina Coronae, Atla Regio (Ozza Mons) and East from it and Atalanta Planitia. VIRTIS near-IR do temperature sounding in the same region. Then cross-correlation on results are made possible. From orbit 612 to 631 there is the VIRTIS apocentre mosaic season. Solar occultations and pendulum observations are mainly performed at the end of the phase (from orbit 690). VeRa have the priority for pericentre observations of the Southern Hemisphere. However, VeRa measurements are not possible from orbit 645 to 658 for NNO maintenance. Dates : January 3 - March 31, 2008. Orbits : 623 - 710 Phase duration : 87 days MTP : 22-25 Phase 13 -------- There is no specific season during most of phase 13. During this phase, pericentre observations, stellar occultation observations, limb observations at pericentre are performed. At the end of the phase 13, in orbit 769, the mission enters superior conjunction phase and telecommunication outage period (orbit 769 to 790) during which all science operations are suspended. Dates : April 1 - June 4, 2008. Orbits : 711 - 775 Phase duration : 64 days MTP : 25-28 Phase 14 -------- Phase 14 starts with the eclipse season #8 and Earth occultation season #6. At the beginning of the phase, the superior solar conjunction prevent any science observations. The eclipse and Earth occultation seasons overlap (orbit 777-821). The Earth occultation period lasts longer up to orbit 832. The targets for the surface observations are East flank of Atla Regio, Ozza Mons, Zevana and Paga Chasma. During this phase, there is a pericentre lowering campaign in orbits 814, 815, 821, 822, 829 and 830. VMC perform surface imaging and wind tracking. SPICAV do solar occultations (ingress and egress solar occultations in orbits 811-819), night and plane limbs and UV observations of the exosphere on the day side. Stellar occultations may be performed in coordination with VeRa. They observe dayglow when flying perpendicular to terminator. Possibly sub-solar point tracking may be performed by SOIR. VIRTIS perform night limbs together with SPICAV and surface imaging. The VeRa Earth occultation experiments begins in orbit 817. Dates : June 5 - July 31, 2008. Orbits : 776 - 832 Phase duration : 56 days MTP : 28-30 Phase 15 -------- There is no specific season during phase 15. The pericentre lowering campaign that began in the previous phase ends at orbit 836 and occur in orbits 836 and 837. SPICAV perform night limbs, plane limbs and stellar occultations. Laterin the phase, SPICAV perform day side limbs. VMC perform wind tracking on the day side. VIRTIS do night side and terminator monitoring and limb observations together with SPICAV at the beginning of the phase. Later in the phase, day side and terminator monitoring is performed. Dates : August 1 - September 22, 2008. Orbits : 833 - 885 Phase duration : 52 days MTP : 30-32 Phase 16 -------- This phase starts with Eclipse season (orbit 866 - 934). During phase 16, there is also a Mosaic season (orbit 903 - 969) and the Earth occultation season #7 (orbit 921 - 985). Pendulum observations are frequently used. There is a joint VIRTIS-SPICAV campaign of night side nadir airglow observations in equatorial zone. There is good opportunity for SOIR nadir observations. SPICAV perform solar occultation and limb observations. VMC perform monitoring, wind tracking on the day side, surface imaging between solar occultations. Around orbit 967, they perform night side imaging of Aphrodite Terra. VIRTIS perform day side monitoring, limb observations together with SPICAV. Later in the phase, VIRTIS also perform Mosaic at apocentre. VeRa perform radio occultations. Dates : September 23 - December 31, 2008. Orbits : 886 - 985 Phase duration : 99 days MTP : 32-35 Phase 17 -------- This phase starts with the end of the Earth occultation season. On orbit 1001 starts a new eclipse season. The mission ends at the end of the Eclipse season, at orbit 1045. SPICAV will observe day and night limbs and do Solar Occultations. VMC will observe night side imaging of the Aphrodite Terra (Ovda Regio, Atla Regio, Sapas Mons, Ganis Chasma) and Rusalka Planitia. VeRa will do radio observation. VIRTIS do observations every second orbit. Dates : January 1 - March 1, 2009. Orbits : 986 - 1045 Phase duration : days MTP : 35-37 Phase 18 -------- This phase includes inferior conjunction. There is no specific season. It focuses on the Venus morning sector. Every second orbit coordinated campaign of ground based observations are organised. SPICAV will observe stellar occultations and day side tangential limbs. VMC will do wind tracking in the evening sector and night side imaging of the western part of Aphrodite Terra (Ovda Regio, Monatum and Tellus Tessera, Tahmina and Aino Planitia). VIRTIS will do terminator studies, limb observations with SPICAV and night side surface observations with VMC. VeRa will do gravity experiment. Dates : March 2 - May 4 , 2009. Orbits : 1046 - 1109 Phase duration : days MTP : 38-39 Phase 19 -------- This phase starts with the Eclipse season (#11), at orbit 1110. It ends when the Eclipse season ends, at orbit 1159. The day side observations have good illumination conditions. The night side surface observations are in eclipse. SPICAV will observe solar and stellar occultations as well as day side tangential limbs. VMC will do day side observations and night side imaging of the Atlanta and Rusalka Planitia and of Atahensik corona. VIRTIS will observe on the day side and limb observations with SPICAV. Dates : May 5 - June 23 , 2009. Orbits : 1110 - 1159 Phase duration : days MTP : 40-41 Phase 20 -------- This phase starts at the end of the Eclipse season (#11), at orbit 1160. It ends after the end of the Earth occultation season (#7) and during the following Eclipse season (#12). VeRa observe during the Earth occultation season and is given the priority. Night side surface targets: Llorona Planitia and Aphrodite Terra. SPICAV do nadir observations around terminator (SO2), solar occultation before pericentre, exospheric limb observation after pericentre. VMC observe night limb (O2 emission and surface) before pericentre and day side nadir after pericentre. They observe in spot pointing mode (see VEX_POINTING_MODE_DESC.TXT) for phase function studies (study of the same place with different light conditions). They also do VMC mosaic (see INSTRUMENT_MODE_DESC.TXT). VIRTIS-H observes meridional cross-sections. Dates : June 24 - Septembre 19 , 2009. Orbits : 1160 - 1247 Phase duration : days MTP : 41-44 Phase 21 -------- This phase starts during the Eclipse season #12, at orbit 1248. During the Eclipse season, the night side of the surface is observed. At the end of the phase (orbits 1271-1275) there is the Drag Campaign #2, meaning that the pericentre pass is devoted to the spacecraft tracking by NNO and no observations within +/- 2 hours from the pericentre are foreseen. SPICAV SOIR is given the priority in pericentre observations. SPICAV observe solar occultation. They do a campaign of nadir night side observations (NO emission). They also observe exospheric limbs. VMC observe day side nadirs. They do mosaic and spot pointing for phase function studies (see phase 20). VeRa do gravity measurements . VIRTIS observe meridional cross sections of the night side. Dates : September 20 - October 17 , 2009. Orbits : 1248 - 1275 Phase duration : days MTP : 45 Phase 22 -------- This phase does not contain any peculiar season. It ends just at the beginning of the Earth occultation season (orbit 1335). The observations focus on the morning sector of the planet. In orbit 1332, there is an OCM. SPICAV follow their previous nadir night side campaign of NO emission. They also do nadir observations of SO2 around terminator. VMC do day side observations with off-track (see explanation above). They also observe night limbs. VIRTIS observe meridional cross-sections. Dates : October 18 - December 16 , 2009. Orbits : 1276 - 1335 Phase duration : 99 days MTP : 46-47 Phase 23 -------- This phase starts at the beginning of the Earth occultation season #13 (orbit 1336). It contains both Earth and solar occultations , but Earth cannot be made due to conjunction. From orbit 1359 to 1378, no science is performed due to telecommunication outage. SPICAV do solar occultations and exospheric limbs. VMC observe in pendulum mode and day side with off-track. pendulum because the observation points to Nadir, then out to space, then back to Nadir, then back to space, etc., mimicking a pendulum movement. VIRTIS observe meridional cross sections. VeRa do not observe due to proximity of the conjunction. Dates : December 17 2009 - February 1 , 2010. Orbits : 1336 - 1382 Phase duration : days MTP : 48-49 Phase 24 -------- This phase has neither Earth nor solar occultations. It starts at the end of the eclipse season (orbit 1382) and ends with the start of the new eclipse season (orbit 1447). The evening sector of the planet is observed. Drag campaign #3 is scheduled for the orbits 1395-1457 and is mainly contained in this phase. A pericentre OCM is scheduled in the orbit 1402 and another one in the orbit 1430. SPICAV observe stellar occultations and limbs with short pendulum every 2 orbit. VMC do pendulum, day side with off track and night limb observations. VIRTIS observe meridional cross sections. Dates : February 2 - April 6 , 2010. Orbits : 1383 - 1446 Phase duration : days MTP : 49-52 Phase 25 -------- This phase starts with the eclipse season #14 at orbit 1447 and ends with it at orbit 1499. During this phase starts the Earth occultation season #9 at orbit 1470. The night side surface of Venus is observed in eclipse. Gravity campaign #11 is scheduled for orbits 1461, 1463 and 1465. An apocentre OCM is scheduled in the orbit 1458. SPICAV observe stellar occultations, solar occultations and exospheric limbs. VMC observe on the day side (latitude tracking, VMC mosaic, spot pointing for cloud phase function). VIRTIS do meridional cross-sections. VeRa perform radio occultations. Dates : April 7 - May 29 , 2010. Orbits : 1447 - 1499 Phase duration : days MTP : 52-53 Phase 26 -------- This phase starts at the end of the eclipse season #14 and ends at the end of the Earth occultation season #9. A pericentre OCM is scheduled in orbit 1500. SPICAV observe stellar occultation, limbs, nadir around terminator (SO2) and Earth. VMC observe on the day side (latitude tracking, VMC mosaic, spot pointing for cloud phase function). VeRa do radio occultations. VIRTIS-H observe meridional cross-sections. Dates : May 30 - July 11 , 2010. Orbits : 1500 - 1542 Phase duration : days MTP : 53-55 Phase 27 -------- This phase starts at the end of the Earth occultation season #9 at orbit 1543 and ends at orbit 1580 (end of the extended mission). Gravity campaign #12 is scheduled at orbits 1545, 1547, 1549, 1551 (tbd 12/05/2009). SPICAV observe stellar occultations and limbs. They also observe nadir around terminator (SO2). They do solar occultation observations after orbit 1571. VMC observe the day side with off track to the day side (latitude tracking, VMC mosaic, spot pointing for cloud phase function). VeRa do radio occultations and the gravity campaign #12, during the Earth occultation season. VIRTIS-H observe meridional cross-sections. Dates : July 12 - August 18 , 2010. Orbits : 1543 - 1580 Phase duration : days MTP : 55-56 Eclipse season ============== Eclipse Dates Season # ------------------------------------- 1 | 16 Apr 2006 - 31 May 2006 2 | 6 Aug 2006 - 13 Sep 2006 3 | 16 Nov 2006 - 10 Jan 2006 4 | 17 Mar 2007 - 26 Apr 2007 5 | 29 Jun 2007 - 21 Aug 2007 6 | 27 Oct 2007 - 9 Dec 2007 7 | 9 Feb 2008 - 1 Apr 2008 8 | 6 Jun 2008 - 20 Jul 2008 9 | 23 Sep 2008 - 10 Nov 2008 10 | 16 Jan 2009 - 28 Feb 2009 11 | 5 May 2009 - 23 Jun 2009 12 | 27 Aug 2009 - 17 Oct 2009 13 | 17 Dec 2009 - 1 Feb 2010 14 | 7 Apr 2010 - 29 May 2010 15 | 30 Jul 2010 - TBC ------------------------------------ Earth occultation Season ======================== Occultation Dates Season # ------------------------------------- 1 | 11 Jul 2006 - 30 Aug 2006 2 | 22 Nov 2006 - 31 Jan 2007 3 | 26 Apr 2007 - 1 Jul 2007 4 | 4 Sep 2007 - 18 Sep 2007 5 | 4 Jan 2008 - 13 Mar 2008 6 | 5 Jun 2008 - 1 Aug 2008 7 | 28 Oct 2008 - 31 Dec 2008 8 | 16 Jul 2009 - 19 Sep 2009 9 | 10 Dec 2009 - 8 Feb 2010 10 | 30 Apr 2010 - TBC ------------------------------------ Solar conjunction (superior) ============================ Solar Dates Conjunction # ------------------------------------- 1 | 17 Oct 2006 - 8 Nov 2006 2 | 29 May 2008 - 19 Jun 2008 3 | 26 Dec 2009 - 28 Jan 2010 ------------------------------------- Spacecraft events ================= Event | Dates | ---------------------------------------------------------------| Launch | 09 Nov 2005 | Earth Moon observations | 22/23 Nov 2005 | Pointing Test 1 | 27 Nov 2005 - 04 Dec 2005 | Interference Test | 14 Dec 2005 - 15 Dec 2005 | Pointing Test 2 | 16 Jan 2006 - 21 Jan 2006 | VOI | 11 Apr 2006 | Capture Orbit Observation 0 | 12 Apr 2006 | Capture Orbit Observation 1 | 13 Apr 2006 | Capture Orbit Observation 2 | 14 Apr 2006 | Capture Orbit Observation 3 | 16 Apr 2006 | Capture Orbit Observation 4 | 17 Apr 2006 | Capture Orbit Observation 5 | 19 Apr 2006 | First Operational orbit | 07 May 2006 | (17th Apocentre) | | Case Commissioning Start | 14 May 2006 | Extended Case Commissioning Start | 24 May 2006 | Nominal Science Start MTP002 | 04 Jun 2006 | Safe Mode 01 | 13 Jun 2006 | Mission Commissioning Results | 04 Jul 2006 | Review | | Safe Mode 02 | 25 Aug 2006 18:15 UTC | Safe Mode 03 | 22 Sep 2006 19:24 UTC | Safe Mode 04 | 27 Sep 2006 04:37 UTC | Safe Mode 05 | 09 Oct 2006 04:20 UTC | VIRTIS-H and VIRTIS-M shutdown | 13 Aug 2007 | due to cooling Motors | | VIRTIS-M restarted | 31 Aug 2007 | Payload Off due to SADE-A | 25-27 Aug 2007 | misalignment | | VIRTIS-H restarted | 04 Nov 2007 | Safe Mode 06 | 27/28 Jan 2008 | VIRTIS-M cooler failure | 27 Oct 2008 23:58 | VIRTIS-M unit resumed non cooler | 28 Jan 2009 | operations in only the | | visible channel | | ---------------------------------------------------------------- Moreover, about every 6 months a SSMM problem (named SCET problem) occurs for about 15 minutes. During this time, the spacecraft cannot record data and the data is lost. This problem does not really affect archive but it is put in the mission catalog as a general information.
