The InSight lander touched down in the Elysium Planitia region of Mars in November 2018 with the goal of studying the planet's deep interior for the first time.
"We know a lot about the surface of Mars, a lot about its atmosphere and ionosphere, but we don't know much about what goes on below its surface," said InSight principal investigator Bruce Banerdt at the start of the mission.
InSight's primary goal was to better understand how rocky planets are formed and evolved. Equipped with a suite of scientific instruments, it was designed to accomplish the mission's goals in its first Mars year ― nearly two Earth years.
Now, after a long and successful mission, the InSight Lander will steadily power down, a process that will be complete by the end of 2022.
Listening to Mars rock
The InSight lander had a number of scientific instruments on board to measure geological and meteorological features on Mars.
One of them is a highly sensitive seismometer, which recorded more than 1,300 Mars quakes. These ranged from tiny tremors, barely more than background noise, to a handful of quakes that were stronger than magnitude 4. And recently, InSight registered a magnitude 5 quake, the largest detected on Mars so far.
Seismic waves pass through or reflect off of materials in Mars' crust, mantle and core. Waves traveling through different materials inside a planet generate different speeds and shapes, which are detected by the seismometer.
"With those vibrations, scientists can take the information to reconstruct all the material that those Mars quakes traveled through, thereby seeing the interior of the planet," said Elizabeth Barrett, InSight science and instrument operations lead.
Three studies published in Science in July 2021 gave humanity its first insights into the structure of Mars. They found Mars has a 24 to 72 kilometer (15 to 44.7 mile) thick crust, likely enriched in radioactive elements that produce heat.
"By measuring the detailed structure of the interior of Mars, we get a snapshot of what it looked like 4.5 billion years ago," said Banerdt.
Weather reports on Mars
The team also set out to make a detailed record of the weather on Mars. The onboard weather station allowed meteorologists to study the weather at the landing site and relate that to the climate changes on Mars.
The InSight lander was going to measure the surface temperature with its onboard heat flow and physical properties probe. The probe was supposed to drill five meters (16.4 feet) below ground level and measure fluctuations in the surface temperature, however the probe failed to reach that depth.
Still, atmospheric temperatures, pressure, wind speeds and wind directions were successfully recorded with InSight's weather station.
InSight sent its last weather report from western Elysium Planitia on October 25, 2020, recording a temperature high of -4.4 degrees Celsius (24 degrees Fahrenheit) and a low of -95.4 degrees Celsius (-140 degrees Fahrenheit).
The latest Mars weather updates come from NASA's Curiosity rover, located about 600 kilometers (373 miles) north of InSight in the Gale crater.
Powering down the mission
After InSight met the goals of its two-year prime mission in late 2020, NASA extended the mission until December 2022.
However, due to dust accumulation on its solar panels, the InSight lander's electrical power production is dropping. With decreasing power, the team will gradually shut down different instruments until InSight will eventually lose power entirely.
The team were able to buy more time this past summer with an innovative method to clean the solar panels ― using dirt. Using a remote control arm with a scoop attached, they dropped heavy dirt onto the panels, knocking some of the dust off.
Currently, the seismometer is still in operation, but it will be turned off in late summer 2022 to preserve power. This is expected to be the end of the InSight lander's science operations before the craft's power levels are so low that it will simply stop responding by the end of 2022.
"InSight has been fantastically successful. We've gotten more science than we had ever dreamed we would get. We've rewritten the encyclopedia chapter on the interior of Mars," said Banerdt.
The mission has generated enough data for scientists to analyze for decades to come. Answering questions on Mars' structure will help shed light on how all rocky planets and satellites form, including Earth and its moon.
But for now, it's over to NASA's Curiosity Rover to continue the mission on Mars.
This article has been translated from German