Techniques d'observation spectroscopique d'astéroïdes

tel-00785991, version 1 - 7 Feb 2013
Abstract: The fundamental goal of the planetary sciences is to understand the formation and
evolution of the Solar System. For achieving this goal, the asteroids are of a special interest to
the astronomical community as a possible window back to the beginning of the planetary formation.
Being the only remnants of the early stages of planetary history they recorded the complex
chemical and physical evolution that occurred in the solar nebula. Thus, the knowledge
of both dynamical and physical properties of the current asteroid population brings valuable
information for understanding the Solar System and more generally other planetary systems.
In this thesis I present the project Modeling for Asteroids (acronym M4AST). M4AST is
an on-line service that I developed for modeling surfaces of asteroids using several theoretical
approaches. M4AST consists into a database containing more than 2,500 spectra of asteroids
together with a library of routines which can model and extract several mineralogical parameters.
The database M4AST could be accessed via its own webpage interface as well as via
the Virtual Observatory (VO-Paris) protocols. This service is available to the web address
http://cardamine.imcce.fr/m4ast. It allows several routines for modeling spectra: taxonomic
classification, space weathering effects modeling, comparison to laboratory spectra of meteorites
and minerals, band centers and band area computing.
I have participated to more than 10 observational campaigns for observing both physical
and orbital parameters of asteroids. The objective of spectral runs was to characterize the
mineralogical properties of these bodies based on their reflectance spectra. Astrometry was
mainly devoted to the confirmation and secures orbits of new discovered asteroid.
During the thesis I observed and characterized near-infrared spectra of eight Near Earth
Asteroids namely 1917, 8567, 16960, 164400, 188452, 2010 TD54, 5620, and 2001 SG286.
These observations were obtained using the NASA telescope IRTF equipped with the spectroimager
SpeX, and the CODAM-Paris observatory facilities. Based on these spectra mineralogical
solutions were proposed for each asteroid. The taxonomic classification of five of these
objects was reviewed and a corresponding type was assigned to the other three asteroids that
were not classified before. 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. The
asteroid (5620) Jasonwheeler exhibits spectral behaviors similar to the carbonaceous chondrite
meteorites.
I observed and modeled six Main Belt Asteroids. (9147) Kourakuen, (854) Frostia, (10484)
Hecht and (31569) 1999 FL18 show the characteristics of V-type objects, while (1333) Cevenola,
(3623) Chaplin belong to S-complex. Some of them have some peculiar properties: (854) Frostia
is a binary asteroid, (10484) Hecht and (31569) 1999 FL18 have pairs, (1333) Cevenola,
(3623) Chaplin show large amplitude lightcurves. The taxonomic classification, the comparisons
to the meteorite spectra from the Relab database and the mineralogical analysis converged
to the same solutions for each of these objects, allowing to find important details for the chemical
compositions and resemblances to the Howardite-Eucrite-Diogenite class of meteorites.