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ESA’s ExoMars mission set to land on Mars Wednesday

Wednesday is a big day for the European Space Agency (ESA). For the first time in its history, it will be (hopefully) landing a probe on the surface of Mars as part of the ExoMars mission, conducted in cooperation with the Russian Space Agency. After more than seven months in space, the Schiaparelli lander module has been released from the Trace Gas Orbiter (TGO) spacecraft and is making its way down to the surface. There was a brief scare early today as the lander was deployed, but the ESA says all systems are go.

ExoMars consists of two parts, the most exciting of which is the Schiaparelli lander. This module is several feet across, and is currently on a ballistic trajectory that will bring it into the Martian atmosphere tomorrow morning. The thin atmosphere of Mars is a bit of a catch-22. It’s thick enough that spacecrafts need heat shields, but not thick enough that a parachute alone is enough for a soft landing.

Space agencies have come up with various ways of coping with Mars landings. For example, NASA’s Spirit and Opportunity landers used giant airbags to cushion their impact on the surface. Meanwhile, Curiosity used the complex but fascinating rocket sled rig to land propulsively.

Schiaparelli will make use of a parachute and thrusters to set down on Mars. When it’s about halfway through the atmosphere, it will deploy a parachute to begin slowing its descent. A few minutes later, the heat shield will be ejected, and shortly after that the lander will detach the parachute. At that point, Schiaparelli will be falling at more than 240 kph (149 mph), but thrusters will used to bring that down to about 4 kph by the time the lander is near the surface. At an altitude of 2 meters, the engines will shut off and Schiaparelli will touch down.

ExoMars-Schiaparelli-lander-ESA

The only hiccup in the mission so far came when Schiaparelli and the TGO parted ways several days ago. The probe had to rotate in order to jettison Schiaparelli on the right trajectory, but that pointed its antenna away from Earth. The ESA team was expecting telemetry data from TGO to come back several minutes later, but they only got a radio carrier wave. Without telemetry, TGO would not have been able to fire its engines to reach a stable orbit. It would have followed Schiaparelli into the atmosphere and broken up. Luckily, the telemetry signal was re-acquired, although no one knows what caused the glitch.

TGO will remain in orbit of Mars to analyze the composition of the atmosphere. In particular, it will search for methane, which would indicate life or geological activity. Meanwhile, Schiaparelli will track wind speed and direction, humidity, pressure, and surface temperature so we can better understand conditions on Mars. The second phase of ExoMars will be handled by Russia with a 2020 launch. You can watch the landing live starting at 1300 GMT tomorrow (9AM Eastern US).

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