NASA executives tried for the last time earlier this month to lure the InSight Lander’s long-range underground heat probe into Martian soil, but after seeing no further progress, ground crews decided to end their efforts and focus on the other scientific objectives of the mission.
The German-built heat probe instrument is one of the top three scientific investigations of the $ 1 billion InSight mission, along with seismic sensors to detect marsquakes and an experiment to track the rotation of the Red Planet measure.
The investigations were designed together to help scientists learn the deep interior of Mars, with an emphasis on studying the planet’s internal structure and composition, Mars tectonics and meteorite impacts. The information will help researchers better understand how rocky planets, such as Earth and Mars, formed and evolved during the 4.5 billion year history of the solar system.
While the other experiments continue to yield results, an underground probe that is part of the InSight Lander’s German-developed package for heat flow and physical properties, or HP3, is having trouble plunging itself into the Martian soil. the months after arriving on the Red Planet. .
The stationary InSight lander touched Mars on 26 November 2018 and ground crews sent orders for the heat probe of the HP3 instrument to be able to dig into the ground on 28 February 2019. It was the first time a mission had attempted to dig so deep into the Martian surface.
Repeated attempts to get the self-hammering 16-inch (40 centimeters) probe into the ground, including attempts to help the creator on the lander’s robotic arm to push the mole into the ground, became empty.
“We have given everything we have, but Mars and our heroic mole remain incompatible,” said HP3 chief investigator Tilman Spohn of DLR, the German Air and Space Center, which developed the instrument. “Fortunately, we have learned a lot that will benefit future missions that try to dig into the underground. ”
The metal peak has built-in temperature sensors designed to measure the thermal gradient in the upper layers of the Martian crust. The mole has a posterior umbilical cord that was supposed to return the scientific data to the InSight lander for transfer to Earth.
But the probe had to reach a depth of at least 10 feet or 3 meters to provide the expected scientific data. Instead, the mole reached only about a foot, or 30 centimeters, below the surface before progressing.
After months of analysis by ground crews, managers approved a plan to use InSight’s robotic arm to remove a mole support housing to inspect the land cameras. According to the camera views, a pit has formed around the perimeter of the mole, indicating that the Martian soil does not offer enough friction or resistance as the self-hammering probe tries to drive itself into the ground.
NASA’s Jet Propulsion Laboratory controllers then attempted to press the robotic arm wrench against the mole to exert extra pressure to compensate for the ground at InSight’s landing site, which apparently collapsed rather than falling off the mole as it hammered. has. .
After NASA said the top of the mole was about 2 to 3 inches below the surface, teams at JPL last tried to use the robotic arm to bump down the peak to provide extra friction. .
“After the investigation on Saturday, January 9, did 500 additional hammer blows, without any progress, the team ended their efforts,” NASA said in a statement.
Credit: NASA / JPL-Caltech
NASA said scientists and engineers learned a lot about the properties of Mars during the mole’s problem solving. The ground at the InSight landing site – on a broad plain called Elysium Planitia – has different properties than material observed in regions explored by other Mars missions.
‘The mole is a device without heritage. What we tried to do – to dig so deep with a small device – is unprecedented, ”said Troy Hudson, a scientist and engineer at JPL, who led the effort to get the mole deeper into the Mars crust. . “The chance to take it to the end is the greatest reward.”
NASA approved an extension of two years for the InSight mission earlier this month.
InSight will continue to measure seismic earthquakes on Mars and produce data to help scientists unravel the internal structure of the Red Planet. The solar-powered Mars lander will also continue to operate a weather station, and ground crews will make plans to bury a tire leading to the InSight seismometer in hopes of eliminating noise in the instrument. can be cleared.
The seismometer has so far recorded more than 480 marsquakes. Prior to InSight, scientists had not confirmed the detection of a seismic quake on the Red Planet.
Lessons learned about using the lander’s robot robot will help engineers devise a plan for burying the tire, according to NASA.
‘We are so proud of our team that worked hard to get the mole of InSight deeper into the planet. It was incredible to see them travel millions of miles, ”said Thomas Zurbuchen, co-administrator of science at the agency’s headquarters in Washington, D.C. That’s why we’re taking a risk at NASA – we need to shift the boundaries of technology to learn what works and what doesn’t. In that sense, we were successful: we learned a lot that would benefit future missions to Mars and elsewhere., and we thank our German partners of DLR for providing this tool and for their cooperation. ”
In 2019, Zurbuchen said the mole is not needed for the InSight mission to meet its minimum criteria for success.
The heat flow measurements to be collected by the HP3 instrument are part of InSight’s so-called ‘Level 1’ requirements, but are listed as a stretch target, or a ‘nice to have’ objective, not as a threshold requirement for minimum mission not success, said Bruce Banerdt, chief investigator of the mission at JPL, in 2019.
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