The ultra-sensitive instruments on NASA’s InSight lander detected a Magnitude 4 “marsquake” on Mars on December 4, 2021. Scientists discovered that the marsquake indicated a meteoroid strike on the red planet when they compared data from InSight to images from the Mars Reconnaissance Orbiter (MRO).
InSight’s seismometer, Seismic Experiment for Interior Structure (SEIS), can detect even the most minute vibrations coming from under Mars’ surface. It normally looks for clues about Mars’ internal activity, which can generate seismic vibrations. However, it can also pick up vibrations from other activity like wind or dust devils, which means it had to be shielded from the atmosphere with a metallic half-dome.
In this case, it picked up the bang from a meteoroid hitting Mars near the equator. The meteoroid kicked up enough of Mars’ surface material to uncover chunks of underground ice that is closer to the equator than has ever been detected before. The presence of underground ice is especially exciting for planners of future crewed mission to Mars because it makes the area a more promising landing site for a long-duration mission.
MRO’s Cameras Detect the Crater
Scientists found the 150-meter-wide crater that the meteoroid made by comparing images from the MRO from before and after InSight detected the marsquake. Scientists working at Malin Space Science Systems (MSSS), which built and operates two cameras for the MRO, first spotted the crater on February 1, 2022.
Images of the blast zone from MRO’s color camera, MARCI, helped them pin down a 24-hour period in which the meteoroid impact occurred – which happened to coincide with the marsquake that InSight detected.
They estimate that the meteoroid was 5 to 12 meters wide.
Most craters on Mars were formed before NASA started sending missions to the red planet. New impacts are rare, but they still (rarely) happen.
“It’s unprecedented to find a fresh impact of this size,” said Ingrid Daubar of Brown University, who leads InSight’s Impact Science Working Group. “It’s an exciting moment in geologic history, and we got to witness it.”
InSight’s Mission May Be Drawing to a Close
InSight provides valuable data about Mars’ interior with SEIS and a thermometer called Heat Flow and Physical Properties Package (HP3). When it landed in Mars’ Elysium Planitia and started arranging its instruments on November 26, 2018, it had to use its robotic arm to “hammer” HP3 into the Martian regolith.
However, once that was done, it started providing valuable data about Mars’ interior. Now, though, dust settling on InSight’s solar panels threatens the mission by causing the lander to start losing power. NASA estimates that its mission has only six weeks left.
The data produced by InSight will still be available for scientists to comb through and compare to the data produced by other assets like the Mars Reconnaissance Orbiter. It may produce interesting scientific discoveries years from now.