chiron, pluto, and triton are among the most exciting bodies in the outer solar system. these three objects are known to have surfaces dominated by volatile frosts and may as a group represent our best link to planetesimals from the early solar system. each apparently accreted in the region beyond 30 au, grew to a size logarithmically intermediate between comets and the giant planets, and developed a volatile rich veneer that generates a tenuous atmosphere. there are already indications that pluto and perhaps chiron exhibit both sublimating (icy) and non-sublimating (inert) surfaces. it is expected that the surface temperature of these bodies is correlated with the cold (sublimating) and warm (non-sublimating) regions. although there is no evidence that triton exhibits thermally-distinct surface units now, it is likely to develop them at some points in its complex seasonal cycles. triton is too close to neptune to be studied by iso. however, chiron and the pluto-charon binary (pcb) are ideal targets for thermal studies by iso. this proposal offers to explore the thermal properties of chiron and pluto with a program of (i) isophot observations designed to obtain dense thermal lightcurves for these bodies at high s/n in various wavebands across their spectral energy distributions, and (ii) lws characterization spectra of each target. we will invert the data lightcurves to determine or constrain the distributions and areal extents of hot and cold regions, and to identify and remove the signal from plutos satellite charon from the pcb lightcurves for the first time. the chiron measurements may also be able to further refine estimates of its diameter. as we describe below, iso provides the only available means to resolve the thermal controversies now surrounding chiron and the pcb, and to constrain the distribution of active areas on their surfaces. the results obtained will also have application to triton, and possibly to the suite of related, chiron-like centaurs and more distant kuiper disk mini-planets now being discovered beyond 30 au.
Instrument
PHT22
Temporal Coverage
1996-12-25T10:01:10Z/1997-01-24T08:53:00Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, STERN et al., 1998, 'A COMPREHENSIVE INVESTIGATION OF THE THERMAL PROPERTIES AND ROTATIONAL THERMAL VARIABILITY OF THE PLUTO-CHARON BINARY AND CHIRON', 1.0, European Space Agency, https://doi.org/10.5270/esa-ynhwl7l
