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A half-scale model of ESA's 2020 Mars rover. It will descend using parachutes and thrusters.


Mars lander crash complicates follow-up rover in 2020

Engineers at the European Space Agency (ESA) are racing to figure out what went wrong with the Schiaparelli Mars lander. On 19 October, it seemed to drop out of the sky and crash to the surface less than a minute before its planned soft landing. A diagnosis is urgent, because many of the same pieces of technology will be used to get a much bigger ExoMars rover down to the surface in 2020.

More than engineering is at stake. If the ExoMars 2020 rover is to fly at all, ESA must persuade its 22 member states to chip in to cover a €300 million shortfall in the €1.5 billion cost of both the 2016 and 2020 phases of ExoMars. On 1–2 December, at a meeting of government ministers, ESA officials will make their case that they are not throwing good money after bad. After the Schiaparelli loss, securing funding for ExoMars 2020 “is really more important than ever, if Europe wants to be seen as part of exploring our solar system,” says David Southwood of Imperial College London, who was ESA’s director of science from 2001 until 2011.

At the ministerial meeting, ESA officials will emphasize the success of the Trace Gas Orbiter (TGO), the other part of the ExoMars 2016 mission. As Schiaparelli fell to its doom, the TGO entered a highly elongated 4.2-day orbit around Mars. Next month, it will begin to calibrate science instruments designed to sniff out methane and other trace gases in the atmosphere to pinpoint their origin—not just where they arise, but whether they emanate from geological or biological sources. In March 2017, TGO will begin dipping down into the martian atmosphere, generating friction that will slow and circularize its orbit so that it can begin science observations later in the year. “We have 100 kilograms of science instruments in orbit around Mars. Solving the mystery of methane is now in our future,” David Parker, ESA’s director of human spaceflight and robotic exploration, told reporters last week.

Compared with the expected science return of the TGO, the weather data that Schiaparelli would have collected with just a few days of battery power on the surface was an afterthought. But as students of ESA’s comet-orbiting Rosetta mission learned, the fate of plucky landers resounds in the public consciousness. In November 2014, Rosetta dropped the Philae lander to the surface of a comet, where it survived a couple days. Even though its few pictures and measurements were far surpassed by those of its mother ship, it captured the public’s fancy and was a public relations coup.

ESA engineers studying what happened to Schiaparelli are working with information from several sources: data the lander transmitted to the TGO during its descent and elements of the same signal that were picked up by ESA’s Mars Express orbiter and a radio telescope on Earth. All sources agree that the signal abruptly stopped around 50 seconds before the expected landing. Early analysis suggested that something went awry after the lander shed its parachute and heat shield and fired its thrusters to slow the final descent. That transition seemed to begin too soon, and the thrusters only fired for a few seconds before cutting out.

On 20 October, the day after the landing, NASA’s Mars Reconnaissance Orbiter (MRO) flew over the landing site and snapped images with its low-resolution camera. These showed a white dot, thought to be Schiaparelli’s parachute, and 1 kilometer away a fuzzy dark patch, 15 by 40 meters in size. ESA says this dark smudge is probably soil disturbed by the impact of Schiaparelli or even the scar of an explosion, since the lander’s propellant tanks would have been full on impact. ESA says the lander probably fell from a height of up to 4 kilometers (the parachute was meant to release it at 1.1 kilometers), and that it would have hit the ground at 300 kilometers per hour. MRO is expected to take more pictures of the site this week with its high-resolution camera.

The pressure is on Schiaparelli’s engineers because the ExoMars 2020 rover and its landing platform are already taking shape. Many components, which are being duplicated from Schiaparelli with little change, need to be shipped to Russia for integration into the spacecraft by next year, says Thierry Blancquaert, Schiaparelli’s mission manager. The aeroshell that will protect the 2020 rover during descent and slow it as it enters the atmosphere is the same shape but instead will be built by Russia, which has been partnering with ESA on the ExoMars program since NASA pulled out in 2012. The parachute in 2020 will be the same type but will deploy in two phases—a small one followed by a big one—and the main chute will be much larger: 35 meters across compared to Schiaparelli’s 12 meters.

The thrusters that will ease the 2020 rover onto the surface will be different, and are currently being developed by Russian space agency Roscosmos. But the radar Doppler altimeter—which senses the surface and allows the thrusters to bring the spacecraft down gently—as well as the guidance and navigation systems will be the same as Schiaparelli’s, so those parts of last week’s descent will be under special scrutiny.

Earlier this year, the planned launch date for the rover was delayed from 2018 to 2020 because of problems mating the ESA-built rover with the Russian aeroshell. Many see this as a blessing in disguise. “The industrial and instrument teams were following aggressive schedules, but the delay is a bit of relief,” says Andrew Coates of University College London, principal investigator of the rover’s PanCam imaging system. “Now there’s time to do something about it.”

It remains to be seen whether government ministers will decide that the 2020 mission is a good bet. Enthusiasts like Southwood say ESA needs to follow the example of NASA which, despite a series of Mars mission failures in the 1990s, kept doggedly at it. “Space exploration is tough. As long as we believe in its societal worth, Europe needs to show the same resolve as our American cousins.”

Even with seven successful landings under its belt, Mars still makes NASA engineers anxious, says Allen Chen, who heads the entry, descent, and landing team for NASA’s Mars 2020 mission at the Jet Propulsion Laboratory in Pasadena, California. Mars’s thin and unpredictable atmosphere means much can go wrong.  Like ESA, NASA is also planning to drop a rover to the surface in 2020, as is China. “Every Mars landing attempt teaches us things,” Chen says. “The only true failure is to stop trying.”

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