| 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. |
