An InSight NASA landing gear was stuck in Martian soil for a month, but engineers came up with a new plan to try and save the device.
InSight, a ground-penetrating heat probe, also known as a "mole", has been stuck in place since February 28. It was supposed to bury the ground 16 feet (5 meters), but it stayed quite short, 14 inches (35 centimeters).
Justice to the mole, this is digging into unknown territory. Never before have they dug so deep in the Martian soil, so it is difficult to predict what the regolith consists of. NASA and the German space agency, which has created the mole and heat and physical properties package (HP3) it is part of, have been working together on alternative fixes since June.
Related: InSight Mars in Photos: NASA's Mission to Probing the Red Planet's Core
(Image Credit: NASA / JPL-Caltech)
Their latest idea is to push a mole on the wall into a hole he created using another tool: the InSight scoop on a robotic arm. Because the mole slides into the hole as it tries to dig further, forcing the tool against the wall can simply work, officials said. "It can increase friction enough to keep it [the mole] moving forward when the hammer is renewed," said Sue Smrekar, deputy chief investigator at InSight NASA's Jet Propulsion Laboratory, in a statement.
The mole is designed to measure the heat flux from the interiors of Mars, which will help answer questions about whether volcanic activity on the planet and how similar the geological histories of Earth and Mars are. This is all the key to NASA's ongoing quest for life on Mars, as life as we know it on planet Earth, formed in an active world, with volcanoes and plate tectonics. It is unclear how geologically active Mars is, and scientists are still learning a lot about such processes as possible "mosquitoes" and volcanic activity.
The mole should be dug autonomously and should not be removed from its pit as soon as it begins to be dug. A few months ago, engineers tried to remove a support structure that should hold the birthmark in place. They did this to better explore the hole and the area in which the mole slides. Images sent back from Mars showed that the mole burrows into a "solid hole" that cemented the soil. No other Mars mission has ever encountered such a ground, and therefore the mole was not designed for this purpose.
The team spent months using a scoop to try to drill a hole, but the arm was used at an angle that no one had anticipated during mission testing. Initially, the scoop was intended to serve as a landscaping tool that would only be used if InSight did not have a clear, level space to place its tools. The HP3 is positioned very far from landing so that the shadow of the spacecraft does not deteriorate with the temperature reading that the heat probe must collect from the underground. The position of the HP3 means that the arm should be far outstretched and press the scoop down at an angle to get a hole that does not give much force to destroy the regolith.
"We ask that your arm be weighed above its weight," said Ashitey Treby-Allenne, a leading weapons engineer at NASA's Jet Propulsion Laboratory in Pasadena, California, in the same statement. "A hand can't push the ground the way a person can. It would be easier if it could, but it's just not the hand we have."
Alternatively, the scoop can be used to bring more soil into the hole so that the mole can restore traction in this way. NASA will continue to monitor the mole and take pictures of its operations. Both methods of salvage, scraping and tapping can be seen in the raw images coming to this site in the coming weeks.
While a rescue operation is forcing engineers to think beyond their original design, this kind of thinking is "New ground for JPL on Mars," the center said. For example, in 2005, engineers helped an Opportunity scooter out of a sand trap, and recently they successfully used alternative drilling techniques with a difficult drill in a long-term Peer of Interest mission.