For the first time, a dwarf planet will receive the visit of a close human probe. And it is this Friday as it happens, the American probe Dawn preparing to enter orbit around Ceres, “little sister” of Pluto between the orbits of Mars and Jupiter . What is the interest of the mission? 20 Minutes collected lighting Peter Beck, a planetary scientist and lecturer at the University Joseph Fourier.

How to explain that Dawn and Ceres passionate least the public and the media that Rosetta and tchouri?

Rosetta was THE great mission of the decade of the European Space Agency , although more expensive than Dawn and also more ambitious. For Rosetta, there was also the challenge, risky landing Philae module. Dawn is a bit more traditional.

And within the scientific community, we are passionate about?

Ceres We are very interested, yes, already in its size: it alone accounts for one third of the total mass of the asteroid belt. Secondly, because it is the first time we will begin orbiting a dwarf planet. Finally, because in the ‘zoology’ of asteroids, it is C-type carbonaceous and supposed to contain organic matter or water. This interest was reinforced when, a year ago, we discovered a thin wrapper around Ceres does contain water leaking episodically. It was a real surprise. Now Dawn was happening and just to photograph two white points on the surface of Ceres. it adds to the excitement.

Precisely, these two bright spots surprised NASA. We know what it could be?

There are three hypotheses. They could be the result of a meteorite impact that would have deposited ice on Ceres. This ice unstable on the surface of the planet, is reportedly evaporate which would produce the brightest points. Second possibility, a comet could have created a crater deep enough so that the material rises, ice-rich -here, the white dots are a kind of window on the inside of Ceres. Latter case, Ceres may have an internal dynamic, and hot cars in places, like volcanic activity.

Hot lifts, therefore water in the liquid state?

Some suggest that there is liquid water inside the planet. Personally I do not really expect me to that, it would be very surprising. But that’s why it is so interesting to explore the solar system objects.

What can we learn about the solar system Ceres?

It contains potentially organic matter and, if there is no liquid water today, it could be some in the past. Or water, minerals and organic matter, is the recipe for life on Earth. Ceres can help to answer this question: is this life is replicable elsewhere than on Earth?