Techniques d'observation spectroscopique d'astéroïdes

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Spectral properties of near-Earth asteroids
tel-00785991, version 1 - 7 Feb 2013
This chapter presents spectra of eight NEAs (1917, 8567, 16960, 164400, 188452, 2010 TD54, 5620, and
2001 SG286 ) obtained using the NASA telescope IRTF equipped with the spectro-imager SpeX. The analysis
of these spectra includes taxonomic classification, comparison with laboratory spectra from Relab database,
and for the S-type objects the correspondent mineralogical models. I also attempted to interpret our data
using a space-weathering model.
The taxonomic classification of five objects was reviewed and a corresponding type was assigned to the other
three asteroids that were not classified before. I found that (1917) Cuyo, (8567) 1996 HW1, (16960) 1998
QS52, (188452) 2004 HE62, and 2010 TD54 are in the S-complex. For these S-type asteroids a good matching
was found with spectra of ordinary chondrites meteorites.
The asteroids (5620) Jasonwheeler and 2001 SG286 were classified as D-type objects. The spectrum of (5620)
Jasonwheeler is similar to spectra of carbonaceous chondrite meteorites. The results found for the two objects
confirm their primitive properties obtained in several other spectral intervals.
Four of the observed objects have delta - V lower than 7 km/sec, which make them suitable targets in terms of
propulsion for a future spacecraft mission.
Near-Earth Asteroids (NEAs) are a continuously changing population of small bodies with
orbits that come close to the Earth’s orbit. Their chaoticity defines them as a critical population,
while several important gravitational field (those of the Sun, Jupiter, and the inner planets) are
superimposed influencing their orbital movement.
Because of the relatively short lifetime of these objects, it is necessary to understand the
dynamical mechanisms of supplying those bodies which are lost (due to expulsion from the
Solar System, falling into the Sun or on the telluric planets) and their reservoirs of objects from
the Main Belt. According to Gladman et al. [2000] the median lifetime of the NEAs is 10 Myr.
On the other hand, NEAs are among the most accessible bodies in the Solar System in terms
of the spacecraft propulsion requirements to reach them. In this sense, the knowledge of the
ensemble of physical parameters for these objects, including their composition, is a critical
point in defining any mission scientific objectives. Currently, several programs (like Marco-
Polo-R, Osiris-REx, Hayabusa2) are under development for space exploration of NEAs.
Another point is that the objects in near-Earth space are a valuable source of information as
they represent a mixture of the different populations of small bodies: main-belt asteroids and
cometary nuclei [DeMeo & Binzel, 2008], and a link with meteorites [Vernazza et al., 2008,