The probe’s robotic arm pulled InSight’s seismometer, known as the Seismic Experiment for Interior Structure or SEIS, from the spacecraft’s deck on Wednesday and slowly, gingerly set it down on a flat spot directly in front of the lander. The arm stretched out to nearly its maximum reach, 5.367 feet away from the deck.
Deploying SEIS is a major milestone for InSight’s two-year mission to monitor seismic activity and internal heat flow on the Red Planet. (The mission’s name is an acronym that stands for “Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.”)
“Seismometer deployment is as important as landing InSight on Mars,” InSight principal investigator Bruce Banerdt, who’s based at NASA’s Jet Propulsion Laboratory, said in a news release. “The seismometer is the highest-priority instrument on InSight: We need it in order to complete about three-quarters of our science objectives.”
SEIS’ seismic sensors are sensitive enough to detect ground movements amounting to less than a hydrogen atom’s radius. For that reason, the guts of the French-built instrument have to be protected inside a vacuum seal.
The experiment is currently sitting on ground that is tilted 2 or 3 degrees. InSight’s next job is to level the seismometer’s position in preparation for collecting the first science data.
“We look forward to popping some Champagne when we start to get data from InSight’s seismometer on the ground,” Banerdt added. “I have a bottle ready for the occasion.”
Whew – winding down after a long day, but I’ve done it: I’ve placed my seismometer on the surface of Mars! With SEIS, I’ll be able to listen in for marsquakes and help reveal the heartbeat of #Mars. https://t.co/GYNO4txPPi pic.twitter.com/18eQHXOfiO
— NASA InSight (@NASAInSight) December 20, 2018
It’ll take several additional weeks to tweak the arrangement of the seismometer and the tether that connects it to the lander, in order to reduce electronic noise to a minimum. Early next month, engineers intend to place a shield over the seismometer to stabilize its thermal environment and protect it from the Martian wind.
If all goes according to plan, InSight’s robotic arm will pick up another important scientific instrument, the German-built Heat Flow and Physical Properties Probe or HP3, and set it down on the surface by late January. HP3 is designed to burrow beneath the surface like a mole and take temperature readings at different levels, down to a depth of 15 feet.
InSight has already started another experiment that uses radio transmissions between Earth and Mars to make precise measurements of the Red Planet’s rotation. The data from the Rotation and Interior Structure Experiment, or RISE, could provide clues as to the size and composition of Mars’ core.
It’s way too early to draw any conclusions about Mars’ interior structure, but the team is pleased with how things have been going so far.
“InSight’s timetable of activities on Mars has gone better than we hoped,” said JPL’s Tom Hoffman, project manager for the InSight mission. “Getting the seismometer safely on the ground is an awesome Christmas present.”