© ESA/Roscosmos/CaSSIS
© ESA/Roscosmos/CaSSIS

First images taken by the ExoMars orbiter

The ExoMars Trace Gas Orbiter (TGO) has imaged the Martian moon Phobos as part of a second set of test science measurements made since arriving in Mars’ orbit on 19 October.

The TGO, a joint endeavour between ESA and Roscosmos, made its first scientific calibration measurements during two orbits between 20-28 November.

Data from the first orbit was published last week, focusing on Mars itself. During the second orbit the instruments made a number of measurements of Phobos, which orbits Mars at a distance of only 6,000km.

The camera imaged the moon on 26 November from a distance of 7,700km, during the closest part of the spacecraft’s orbit.

The camera’s filters are optimised to reveal differences in mineralogical composition, seen as ‘bluer’ or ‘redder’ colours in the processed image.

Nick Thomas, principal investigator of the CaSSIS camera team at the University of Bern, Switzerland, said: “Although higher-resolution images of Phobos have been returned by other missions, such as ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter, this provided a good test of what can be done with our data in a very short time.

“The images have given us a lot of useful information about the colour calibration of the camera and its internal timing.”

Two other instruments also made calibration measurements of Phobos, and the teams are analysing their data.

Håkan Svedhem, ESA’s TGO project scientist, added: “We’re very happy with the results of both test science orbits and will be using these calibration data to improve our measurements once we begin the main science mission later next year.”

TGO’s main scientific goal is to make a detailed inventory of rare gases that make up less than 1% of the atmosphere’s volume, including methane, water vapour, nitrogen dioxide and acetylene.

TGO will also act as a data relay for present and future landers and rovers on Mars, including the second ExoMars mission scheduled for launch in 2020.