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NASA officials last attempted to get the InSight lander’s underground heat probe long stuck in Martian soil earlier this month, but after seeing no further progress, teams at sol decided to end their efforts and concentrate on the other scientific objectives of the mission.
The German-made thermal probe instrument is one of the three main scientific investigations of the InSight mission, with seismic sensors to detect “marsquakes” and an experiment to measure the oscillation of the rotation of the red planet.
Together, the surveys were designed to help scientists discover the deep interior of Mars, with an emphasis on studying the internal structure and composition of the planet, Martian tectonics, and meteorite impacts. . This information will help researchers better understand how rocky planets, like Earth and Mars, formed and evolved over the Solar System’s 4.5 billion year history.
As the other experiments continue to yield results, an underground probe that is part of the heat flow and physical properties package of the German-developed InSight lander, or HP3, has encountered problems sinking into the ground. Martian in the months following his arrival on the Red Planet. .
The InSight fixed lander landed on Mars on November 26, 2018, and ground crews sent out commands for the HP3 instrument’s thermal probe to begin burrowing into the ground on February 28, 2019. It was the first time a mission tried to dig so deep. the Martian surface.
Repeated attempts to force the 16-inch (40 centimeter) self-hammering probe into the ground, including attempts to use the shovel on the lander’s robotic arm to help push the mole into the ground, turned out to be empty.
“We gave it our all, but Mars and our heroic mole remain incompatible,” said HP3 principal investigator Tilman Spohn of DLR, the German aerospace center, who developed the instrument. “Fortunately, we’ve learned a lot that will benefit future missions that attempt to dig underground.
The metal tip has built-in temperature sensors designed to measure the thermal gradient in the upper layers of the Martian crust. The mole has a trailing umbilical attachment that was supposed to send science data back to the InSight lander for transmission 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 only reached about a foot, or one foot, below the surface before its progress slowed down.
After months of analysis by ground crews, officials approved a plan to use InSight’s robotic arm to remove a support structure box to reveal the top of the mole for inspection by the cameras on the ground. ‘lander. Camera views revealed that a pit had formed around the circumference of the mole, suggesting that Martian soil was not providing enough friction, or resistance, as the self-hammering probe attempted to sway. sink into the ground.
Controllers at NASA’s Jet Propulsion Laboratory then attempted to use the robotic arm’s shovel to press against the mole in an attempt to apply additional pressure to compensate for the ground at the InSight landing site, which appeared clumping rather than falling loosely around the mole as it pounded. .
After placing the top of the mole about an inch, or 2-3 centimeters, below the surface, JPL teams made a final attempt earlier this month to use the robot arm’s shovel to tamp down the tip to provide additional friction, NASA said. .
“After the probe made 500 more hammer blows on Saturday, January 9, with no progress, the team called for an end to their efforts,” NASA said in a statement.
Credit: NASA / JPL-Caltech
NASA said scientists and engineers learned a lot about the properties of Martian soil when troubleshooting the mole. The soil at InSight’s landing site – on a wide plain called Elysium Planitia – has different characteristics than the materials seen in regions explored by other missions to Mars.
“The mole is a device with no heritage. What we have attempted to do – dig so deep with such a small device – is unprecedented, ”said Troy Hudson, a scientist and engineer at JPL who led the effort to push the mole deeper into the Martian crust. “To have had the opportunity to see it all through to the end is the greatest reward.”
NASA approved a two-year extension for the InSight mission earlier this month.
InSight will continue to measure earthquakes on Mars, producing 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 develop plans to bury a tether leading to InSight’s seismometer in the hopes of eliminating noise in the instrument’s data.
The seismometer has so far recorded more than 480 earthquakes in March. Before InSight, scientists had not confirmed the detection of a seismic tremor on the Red Planet.
Lessons learned about using the lander’s robotic arm will help engineers devise a plan to bury the tether, according to NASA.
“We are very proud of our team who have worked hard to bring InSight’s mole deeper into the planet. It was incredible to see them troubleshooting millions of miles away, ”Thomas Zurbuchen, associate administrator for science at the agency’s Washington headquarters, said in a statement. “That’s why we take risks at NASA – we have to push the boundaries of technology to know what works and what doesn’t. In this sense, we have succeeded: we have learned a lot that will benefit future missions to Mars and elsewhere., and we thank our German DLR partners for providing this instrument and their collaboration. “
In 2019, Zurbuchen said the mole was not needed for the InSight mission to meet its minimum success criteria.
The heat flux readings intended for collection by the HP3 instrument are part of InSight’s so-called “level 1” requirements, but have been listed as an expandable lens, or a “nice to have” lens, not as a. a threshold requirement for a minimal mission success, said Bruce Banerdt, senior mission researcher at JPL, in 2019.
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