More than one month has now passed since the arrival of Europe’s ExoMars mission at the Red Planet. While the mission’s Schiaparelli module has crashed into the Martian surface, the Trace Gas Orbiter (TGO) is in excellent shape and preps for science operations.
ExoMars began its journey to Mars on Mar. 14, 2016. Seven months later, on Oct. 16, the Schiaparelli module had been successfully separated from the TGO, heading for a risky descent towards Martian rocky surface three days later. Apparently, the lander’s back heat shield and parachute were ejected prematurely what caused the crash. However, it is only a hypothesis as the full analysis of the failure is not yet complete and an independent inquiry board has been initiated to investigate the event.
“An independent inquiry board will look into the non-nominal landing sequence. We know that after the deployment of the parachute the three clusters of thrusters did only work for a few seconds and that Schiaparelli fell from an altitude of two to four kilometers, reaching the surface at more than 300 km/h (186 mph),” Markus Bauer, ESA Science and Robotic Exploration Communication Officer, told Astrowatch.net.
TGO had a much easier task to accomplish than Schiaparelli. After the successful deployment of the lander, it was scheduled to be injected into Martian orbit on Oct. 19. The orbiter completed this milestone flawlessly and is now cruising towards a highly elliptical path that takes it from an altitude of between 143 and 193 miles (230 and 310 kilometers) to around 60,900 miles (98,000 kilometers) every four days and five hours.
“TGO works nominal as well as its instruments. It is a spacecraft in its own right, scientifically and operationally,” Bauer said. “Apart from delivering Schiaparelli successfully to Mars and relaying data from it, TGO and Schiaparelli are two separate missions, with different scopes. Schiaparalli was a technology test. TGO is a full fledged science and communication satellite in orbit of Mars,” he added.
The orbiter’s instruments are now being calibrated and the mission controllers are now conducting first test observations. This is required to make sure that the spacecraft is working properly ahead of the start of its science mission in March 2018. By then the aerobraking will be finished and TGO will be in a circular orbit at an altitude of about 248 miles (400 kilometers) above the surface of Mars.
When in circular orbit, TGO will then fully concentrate on its science tasks, mainly detecting and analyzing methane and other trace gases.
“Scientifically it is of interest whether Mars atmospheric trace gases emanate from a specific region on Mars and to understand their source. Of specific interest is the origin of methane. TGO will solve the mystery of the origin of methane,” Bauer noted.
Although TGO’s main scientific goal is to search for evidence of methane and other trace atmospheric gases, the spacecraft will also relay communications of NASA rovers on ground and will be instrumental for ESA's future ExoMars rover, which will operate on Mars as of 2021.
TGO was built by Thales Alenia Space. The orbiter’s dimensions are 11.5 ft × 6.5 ft × 6.5 ft (3.5 m × 2 m × 2 m) with solar wings spanning 57.4 feet (17.5 meters) and providing up to 2,000 W of power. It has a mass of approximately 4.3 metric tons. The TGO is equipped with four scientific instruments for the detection of trace gases: Nadir and Occultation for MArs Discovery (NOMAD), Atmospheric Chemistry Suite (ACS), Colour and Stereo Surface Imaging System (CaSSIS), and Fine Resolution Epithermal Neutron Detector (FREND).