NASA’s groundbreaking Insight lander on Mars has fallen silent.
It was a sad moment, though we knew it was coming: After four years of collecting data on Mars, the Insight mission, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, has come to an end. The lander missed its last two communication passes and last “phoned home” on December 15th.
The team was expecting the sudden silence, as dust storms had left a fine sandy silt on the lander's solar panels. The panels are designed to produce 600 watts, but that has decrased over the past few months and was down to less than 300 watts in the mission's final days.
December 26th marked the start of spring in the northern hemisphere on Mars, when the weather begins to clear, and NASA will continue to listen for the lander via the worldwide Deep-Space Network; however, prospects aren’t good.
Based around the same frame as the Phoenix lander, Insight launched from Vandenberg (then Air Force, now Space Force) Base in California on May 5, 2018. The launch also carried the Mars Cube One Marco A and B smallsats past the Red Planet, marking a first for interplanetary CubeSats.
Insight landed at Elysium Planitia on November 26, 2018. The first dedicated planetary science geodesy mission, Insight’s goal was to study surface seismic activity and measure subsurface heat transfer in an effort to model the interior of the planet and understand the geological history of Mars.
“We’ve thought of InSight as our friend and colleague on Mars for the past four years, so it’s hard to say goodbye,” says Insight's principal investigator Bruce Banerdt (JPL). “But it has earned its richly deserved retirement.”
The Seismic Experiment for Interior Structure (SEIS) that Insight deployed detected 1,319 marsquakes, cataloged by the Marsquake Service and the French space agency, Centre National d'Etudes Spatiales (CNES). Generated by movements internal to Mars as well as by meteoroid impacts, the quakes revealed the structure of the planet's interior, including a surprisingly thin crust, an undifferentiated mantle, and a larger-than-expected core. SEIS was the last instrument to be powered and gathered information until the very end.
The lander also chronicled Martian weather and found strong remanant magnetic fields buried in the crust. The mission even detected the tiny dips in solar power when the tiny Martian moons Phobos and Deimos passed across the face of the Sun.
The Heat Flow and Physical Properties Package, nicknamed “the mole,” had more trouble. The self-hammering heat probe was designed by the German Aerospace Center (DLR) to burrow 5 meters (16 feet) into the sandy soil expected at the landing site. What the mole instead encountered was hard, clumpy soil that refused to give. Engineers attempted to push the mole with the lander’s robotic arm numerous times, but ultimately the mole was buried just below the surface. While it wasn't able to collect data on the planet's heat transfer, it nevertheless did collect some data.
Manipulation of the heat probe wasn't the only innovative use of the lander's robotic arm. The team also used it to “dry clean” the twin solar panels by scattering dirt on them. The silty dust that covered the panels clung to the bigger particles as the wind swept them across, clearing off the panel. The robotic arm was put in a retirement pose after final use earlier this year.
The loss of Insight means that only two missions — the Curiosity and Perseverance rovers — remain active on Mars. The next possible mission is the European Space Agency’s Rosalind Franklin rover; delayed due to the Ukraine war, it's now set to launch in 2028.
“I have the profound feeling that Insight will remain, for seismology and planetology, as one of the historical missions,” says Philippe Lognonné (Institut de Physique du Globe de Paris). “We have contributed to the installation of the seismic station farthest from the Earth, we have reached (thanks to the performances of our seismometers) sensitivity never experienced on Earth and even on the Moon, and we have discovered so much!”
The lander will now sit silent on Elysium Planitia, a testament to humanity’s first dedicated geodesy mission to the Red Planet. If skies are clear, look at Mars high to the east at sunset tonight, and pause to remember intrepid Insight.