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Project Progress

The goal of this project is to constrain how ubiquitous water is in the outer solar system (beyond 20-30 UA from the Sun). For water-bearing objects, we want to determine whether water is in its crystalline or amorphous phase, which has some strong implications on temperature and physical conditions state and history in these regions of the solar system. The study of physical properties of populations related to the Kuiper Belt (comets, irregular satellites of the outer planets) may cast some light on potential object transport mechanisms. During these surveys, objects are also searched for other ices and organic material. The technical tool is visible and near-infrared reflectance spectroscopy using 8-10 meters telescopes on Mauna Kea Observatory. These wavelengths (especially the 1-2.5 microns range) host the signatures of most of the ices and organic material we are looking for, that are of prebiotic interest.

We first studied giant Kuiper Belt Object Orcus with the Gemini 8m-telescope (near infrared spectroscopy). Our study shows the presence of water ice most probably in its crystalline state. It implies that the temperature was above 105K in the past. We are also looking for methane and so far never detected ammonia ice. Results will be finalized shortly. Outstanding detections will be published in a high impact factor journal such as Science or Nature.

We are also focusing on Neptune and Uranus icy satellites. Telescope time at Subaru allowed us to study Neptune’s satellite Nereid (which most probably shows crystalline water ice). Analysis is in progress and more observing time is scheduled during summer 2006 to complete this spectroscopic survey. Final results for both the satellites and Orcus will be ready by fall 2006.