ESA’s Trace Gas Orbiter satellite immortalises InSight from Martian orbit
On March 2nd 2019, the Trace Gas Orbiter (TGO) probe of the European Space Agency's ExoMars program succeeded in photographing the InSight probe on the surface of the Red Planet. This is the first time that a European satellite has achieved this technical feat, which requires not only a high-performance camera, but also special shooting conditions, given the relatively small size of the devices to be resolved.
Publication date: 05/03/2019
Observatories, Press, Research
Related observatories : InSight Observatory
Related themes : Earth and Planetary Interiors
Launched on March 14th 2016, the Trace Gas Orbiter probe entered Martian orbit on October 16th of the same year, almost thirteen years after the European Space Agency’s first Mars probe, the Mars Express satellite. After a year of aerobraking to reach its final mapping orbit, TGO began its scientific observation campaign at the end of April 2018. While its main objective is to study in great detail the gaseous species that make up the Martian atmosphere, the orbiter can also fulfil other roles, including that of radio relay.
Trace Gas Orbiter carries two Electra radio transponders, supplied by NASA, enabling it to communicate with exploration vehicles on the surface, including the InSight probe.
Together with the US space agency’s Mars Reconnaissance Orbiter (MRO) and Mars Odyssey (MO) satellites, TGO has been regularly relaying to Earth the data provided by this geophysical station since it landed on Elysium Planitia on November 26th, including during critical operations.
Trace Gas Orbiter carries two Electra radio transponders, supplied by NASA, enabling it to communicate with exploration vehicles on the surface, including the InSight probe. Together with the US space agency’s Mars Reconnaissance Orbiter (MRO) and Mars Odyssey (MO) satellites, TGO has been regularly relaying to Earth the data provided by this geophysical station since it landed on Elysium Planitia on November 26th, including during critical operations.
Until now, the geometry of the overflights of InSight’s landing site had made it impossible to point TGO’s CaSSIS camera at the lander and the equipment it left behind on its perilous descent towards the Martian equator. On March 2nd, just as the HP3 heat flux sensor had begun its attempts to sink below the surface, TGO passed directly over InSight, a configuration that made it possible to take a snapshot of the landing site.
While the image obtained by TGO is admittedly less precise than the images acquired by the HiRISE spy camera on Mars Reconnaissance Orbiter (MRO) in December 2018 and February 2019, it nevertheless shows several details, such as the blast zone around the lander (where the dust was blown up by the retrorockets), the heat shield and the rear shield (although the parachute fabric is not clearly identifiable). The image covers an area of 2.25 km2, and the resolution varies from 5 to 6 metres per pixel (compared with HiRISE’s resolution of 25 cm/pixel). The image has not been reoriented to place north at the top.
In addition to its role in telecommunications, TGO will continue to support InSight by photographing the regions around the landing site at regular intervals, to identify any new meteorite impacts. To determine the internal structure of Mars, the SEIS seismometer can rely on two seismic sources: tremors caused by sudden ruptures of rocky material in the Martian crust and mantle, and shock waves linked to the impact of extraterrestrial bolides on the surface. The ability to pinpoint the location of an impact (and therefore the epicentre of the associated earthquake) will greatly assist the interpretation of the data recorded by SEIS.
