A joint mission led by the European Space Agency and Roscosmos arrives at Mars next week, and its first order of business will be to make history. If all goes well, NASA is about to lose its bragging rights as the only space agency to successfully land probes on the Red Planet. How things will hopefully go down for the Schiaparelli lander on October 19. Image: ESA
ExoMars, an astrobiology mission designed to hunt for signs of geologic and biological activity on Mars, is on track to reach orbit on October 19. When it arrives, the mission's two components — a Trace Gas Orbiter (TGO) and a Schiaparelli lander — will part ways. The TGO will insert itself into a low-altitude orbit and begin scanning the Martian atmosphere for methane, water vapour and other trace gases. Schiaparelli, meanwhile, will attempt to reach the surface in one piece.
Landing on Mars is hard, and neither the ESA nor the Russians have a great track record. In the 1960s and '70s, the Soviet Union sent a slew of probes to the Red Planet, all of which crashed, died shortly after impact or missed their target entirely. In 2003, the ESA's Beagle 2 lander made it to the surface, but its solar panels failed to deploy, and it lost contact with Earth. In 2011, the Russians launched a space probe intended for Mars' moon Phobos. It never made it out of low Earth orbit, eventually falling back and burning up in our atmosphere.
In other words, ExoMars is arriving at its destination with some baggage and a lot to prove. On October 16, Schiaparelli and TGO will separate. Three days later, the lander will enter Mars' atmosphere. The angle has to be absolutely perfect, otherwise the probe will come in too hot and burn up, or bounce back into space. If all goes well, Schiaparelli with then deploy a braking parachute, followed by three sets of hydrazine thrusters. All the while, it will be collecting data to characterise the structure of the Martian atmosphere and its intended landing site.
The entire sequence is pre-programmed, and Schiaparelli only has one shot. There are no do-overs should anything go wrong.
Lucky for the ESA and Roscosmos, Schiaparelli's main goal is demonstrate landing technology. If there is a problem, engineers will study it carefully and incorporate whatever lessons they learn into the next phase of the ExoMars mission — a bigger and longer-lived science lander that ships off in 2020. So while everyone is hoping to stick the landing next week, failure to do so is not a catastrophe.
One way or another, this will be an exciting mission to watch.