Tuesday, 16 August 2022

Mars InSight Lander Unexpectedly Finds Little to No Ice Below

The NASA InSight lander.

NASA didn’t get everything it wanted from the InSight Mars lander, but the mission still pioneered new types of science on the red planet. The mission is now in the rearview mirror, but planetary scientists are still digging through the data to see what the lander can teach us about the interior of Mars. A new publication in Geophysical Research Letters has a surprising hook. Defying expectations, there is little to no ice in the top 300 meters under InSight. 

InSight was the first mission to take a hard look below the dusty surface of Mars. It included a seismometer, the first ever deployed on another planet, as well as a burrowing heat probe. Sadly, the Martian soil around the lander in Elysium Planitia flowed too freely, allowing it to continuously collapse into the tunnel dug by the probe. NASA eventually called off efforts to get the instrument deeper underground. The seismometer, known as the Seismic Experiment for Interior Structure (SEIS), worked flawlessly, though. By monitoring the vibrations caused by marsquakes and combining that data with our extensive knowledge of surface formations, it was possible to characterize the planet’s interior. 

The mission returned ample data on Mars, including the revelation that the planet’s crust is “weak” and “not well-cemented.” According to researchers at the University of California San Diego, the consensus prior to InSight was that much of the void space would be filled with ice, but that does not appear to be the case. It’s still possible that there could be small ice crystals in the crust, but that’s just speculation. 

The other surprising finding contradicts prevailing theories about what happened to Mars’ water. We know the planet had oceans a billion years ago, but they were lost along with its atmosphere. Experts have long suspected that Martian water was locked up in mineral deposits like clay. After running their models 10,000 times, the team has concluded that InSight found no evidence of cemented minerals around its landing zone near the planet’s equator. 

If other studies can confirm this, it could change the way future Mars missions are designed. If life still exists on the planet, scientists believe it would be buried in mineral deposits and aquifers, which would protect it from high radiation on the surface. Without such deposits around the equator, missions may have to focus on the polar regions, which are known to have large deposits of frozen groundwater, as well as surface ice. Similarly, human missions in the future that hope to harvest water from within Mars may need to choose landing zones at higher latitudes.

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