The following document lists the file abstract/THENCRE_GALSAT.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
SCIENTIFIC ABSTRACT
ISO is expected to make unique contributions to composition studies of
galilean satellites and asteroids with its spectroscopic capabilities,
especially at wavelengths 2.5-5 microns. These observations, using
PHT S1-S2, will provide new insights into the chemical composition of
the galilean satellites and the mineralogy of asteroids. They will
have implications about the formation processes of these objects and
the early history of the Solar System.
Galilean satellites are known to be very different from one another.
Io's surface is dominated by sulfur compounds, but their exact nature is
still controversial. The three other satellites are basically covered with
ice. A complete spectral coverage of the 2.5-12 micron range will help
to characterize their chemical nature, and will provide an important
input at the time of the satellites'exploration by the Galileo spacecraft.
Most of our knowledge about asteroids has come from visible and near-IR
spectro-photometry (below 2.5 microns). ISO observations at longer wavelengths
will be essential for analysing, in particular, their carbonaceous content
(around 3.4 microns), the nature of their hydrated minerals (in the
2.6-3.1 micron range), and the nature of their silicate feature at 8-12 micron.
As a moderate spectral resolution is sufficient to explore the spectroscopic
features of the solid surface material, we will use PHT S1 ans S2 which will
ensure maximum sensitivity. The PHT-S1 part will explore the reflected
component (2.5-5 micron) and the PHT-S2 part (6-12 micron) will simultaneously
provide the thermal component.
OBSERVATION SUMMARY
We plan to observe the following list of objects with PHT S1-S2 (AOT PHT40),
and with PHT P (AOT PHT03) in 2 filters (3.4 micron and 10 micron) for absolute
calibration.
Table 1 gives the list of the targets with their class, their diameter,
their flux at 3.3 micron, the total observing time of the 2 observations
(AOT PHT03 and PHT40), the expected S/N in the PHT-S spectrum at 3.3 micron,
and the priority of the observation.
In the case of an autumn launch, 324 Bamberga is not observable; in the case
of a spring launch, 2 Pallas and 31 Euphrosyne are not observable; in the
second case, 87 Sylvia is added to the list of targets.
TABLE 1
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Object Class Diameter 3.3mu Flux Obs.time Exp.S/N Prio.
(km) (mJy) (s)
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GALILEAN SATELLITES
Io 3632 6200 409 80 1
Europa 3138 5100 429 80 1
Ganymede 5262 16000 361 80 1
Callisto 4800 15000 369 80 1
ASTEROIDS
1 Ceres G 913 1700 404 40 1
2 Pallas B-C (*) 583 710 679 40 1
3 Juno S 220 400 917 40 1
4 Vesta V 380 1200 549 40 1
10 Hygiea C 443 410 917 40 3
52 Europa CF 291 180 977 30 3
324 Bamber CP (**) 256 140 1132 30 3
704 Interam C 338 240 1017 30 3
65 Cybele C 311 200 1075 30 3
31 Euphrosy C (*) 270 150 1132 30 3
87 Sylvia P (**) 271 150 679 20 3
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(*) For autumn launch only
(**) For spring launch only
TOTAL TIME (s) Autumn launch Spring launch
Priority 1 4117 3438
Priority 3 5118 5797
Total 9235 9235