CaSSIS sends first image of Mars

CaSSIS (Colour and Stereo Surface Imaging System) has been developed by a team led by the University of Bern. It was launched with the European Space Agency's ExoMars Trace Gas Orbiter (TGO) in March and has already travelled just under half of its nearly 500 million km journey.

While the orbiter's 'first-light' image of a star field was successfully acquired within the first month following launch, it has now set sights on its destination.

The orbiter and Mars were 41 million kilometres apart on 13 June when the new image was taken. Although it does not compare to the high-resolution scenes that will be returned once the spacecraft is finally at Mars, it is an important milestone for the camera team.

Camera is working well

"The images have confirmed the sensitivity of the instrument and are sharp," says Antoine Pommerol, co-investigator of the Colour and Stereo Surface Imaging System (CaSSIS) of the Center for Space and Habitability (CSH) at the University of Bern. "CaSSIS seems to be well-focussed and the signal level seems to be close to prediction."

"Telescopes on Earth and the Hubble Space Telescope in orbit around it can still do far better than us at present, but we are still a long way away from Mars," says Nicolas Thomas, the camera's principal investigator at the CSH.

"If the instrument continues to perform well, the indications are that we should begin to exceed what is achievable from Earth in the second week of October, and then the improvement in resolution will happen rapidly."

With another four months of journey time ahead, the team will continue to look at the data they are collecting en route. "Everything we do now helps us to understand and calibrate the instrument," adds Nick. "There's a lot to prepare for."

Observing dynamics on Mars

CaSSIS is a high resolution imaging system designed to complement the data acquired by the other payload on TGO and other Mars orbiters while also enhancing our knowledge of the surface of Mars. The camera is a cooperation between the University of Bern, the Astronomical Observatory of Padua, and the Space Research Center in Warsaw with the support of local industries and funded by the Swiss Space Office (SSO), the Italian Space Agency (ASI) and the Polish Space Agency (POLSA). The instrument will obtain stereo images of the surface in colour at a resolution of better than 5 m.

It is now known that Mars is more dynamic than previously thought. Of particular interest to the 25-strong science team from 9 countries (incl. US and Russia) is the chance CaSSIS offers to study changes that occur over the day and over the Martian seasons. Further studies of recently discovered liquid water on the surface will be one of the main aims.