On a continent known for its violent storms, the idea may seem surprising at first. But, take a closer look. The Antarctic high plateau is a vast, virtually flat expanse of snow and ice at an altitude ranging from 3,000 to 4,000 meters. Hardly any wind blows but sky quality is like sky over high mountain ranges. Not to mention that nighttime lasts several months. All these reasons beg the question of the Antarctic's potential for astronomy. Of course, the most appropriate type of astronomy for the region remains to be determined. Eric Aristidi, Senior Lecturer at Nice Sophia-Antipolis University and research scientist at the Laboratoire Universitaire d'Astrophysique de Nice (LUAN, Nice university laboratory for astrophysics) talks about current and future projects. Interview by Jean-François Desessard.
BE France - A program called Concordiastro was launched in November 2000. Where does it stand and what are its results?
Eric Aristidi - The program was submitted by a group of French and Italian astronomers led by Eric Fossat who also works at the LUAN. Concordiastro works on qualifying the astronomic properties of Dome C, a local 3,300-meter summit on the Antarctica plateau where the Concordia French-Italian base is located. Since November 2000, the research, which is conducted during every summer season with an extension during 2005 and 2006 overwintering, has shown that Dome C is undoubtedly the world's best astronomy site. During overwintering, LUAN engineer Karim Agabi and myself have observed that the sky is clear more than 80% of the time. Also, for something called "seeing", meaning image sharpness, it is twice as good as at it is at Mauna Kea, Hawaii, now considered and the world's best astronomy site.
At Dome C, atmospheric turbulence is much slower than elsewhere. Turbulence layer thickness is only thirty meters high in winter and 90% of the turbulence remains on the ground whereas, in other parts of the planet, the turbulence is usually broken down into layers over an altitude of several kilometers. Another extremely interesting feature of Dome C is the low water vapor rate in the atmosphere, meaning that stars with weak luminosity can be observed at infrared wavelengths and in visible light.
BE France - I suppose that the assets inevitably prompt astrophysicists, such as yourself, to design future projects and imagine future observation tools adapted to the site?
Eric Aristidi - Indeed, we have started thinking about what could happen after Concordiastro. We have submitted a program called Astro-Concordia. This involves going gradually from the current site qualification period to the performance of targeted experiments that could be demonstrators adapted to the special conditions of polar land.
This is how the idea of attempting to detect chlorophyl, in other words extraterrestrial life, on an extrasolar plant was born. Thus, during the next overwintering, we should have a telescope prototype so we can observe the Moon's 'earthshine' from the Earth, which is like looking at Earth's light in a mirror. The advantage of the polar regions is the fact that earthshine is visible for many hours on end, meaning we can observe the changes when the Earth turns and its oceans or continents are turned toward the Moon. In a more distant future, we could apply the technique to test-stars, which would require a bigger telescope.
In an even more distant future, i.e., in about twenty or thirty years, we are planning to instal an interferometer with 36 1.5-diameter optic telescopes spread out over one hundred hectares, and whose performance would be comparable to a giant one-kilometer diameter telescope! This is the goal of the KEOPS project now in its preliminary study phase.
