Going out with a bang, NASA's InSight Mars lander, slowly dying as light-blocking dust builds up on its solar arrays, detected the most powerful marsquake yet recorded May 4, a magnitude 5 temblor 10 times stronger than the previous record holder.
Now operating with one-tenth the power its arrays generated when it, InSight will be forced to end continuous operation of its ultra-sensitive seismometer sometime this summer, officials said Tuesday, a prelude to the end of science operations later this year.
"We're still doing great science at Mars," said Bruce Banerdt, the InSight principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, California. "Even as we're starting to get close to the end of our mission, Mars is still giving us some really amazing things to see and to add to our data record."
The recently detected magnitude 5 marsquake was the strongest ofthe spacecraft has detected since landing.
"Basically, we've been able to map out the inside of Mars for the very first time," Banerdt said. "We're able to get the size of the core, we're able to deduce something about its density and therefore the composition of the core. We've detected the bottom of the crust, and we're able to determine the thickness of the crust."
In addition, data from InSight - a convoluted acronym that stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport - has allowed researchers to probe the martian mantle and learn more about its temperature and its mineralogical structure.
"InSight has transformed our understanding of the interiors of rocky planets and set the stage for future missions," Lori Glaze, director of NASA's Planetary Science Division, said in a statement. "We can apply what we've learned about Mars' inner structure to Earth, the moon, Venus and even rocky planets in other solar systems."
InSight was launched May 5, 2018, and plunged to a successful landing in a region of Mars known as Elysium Planitia on Nov. 26 that same year. Unlike the nuclear-powered Curiosity and Perseverance rovers, InSight is a stationary, solar-powered spacecraft with a more limited agenda.
It is equipped with two primary instruments, the Seismic Experiment Interior Structure - SEIS - seismometer, provided by the French space agency, and the Heat Flow and Physical Properties Probe - HP3 - provided by the German Aerospace Agency, DLR. In addition, the lander carries a suite of sophisticated weather instruments.
A small robot arm placed the two primary instruments on the surface shortly after landing, but the temperature probe, designed to hammer its way 15 feet below the surface to measure the heat flowing from the martian core, was unable to penetrate the frigid soil more than a few inches.
The seismometer, sensitive enough to measure vibrations as small as the width of an atom, has worked flawlessly throughout the mission.
But the end is now in sight, so to speak.
Kathya Zamora Garcia, InSight's deputy project manager, said the spacecraft's two seven-foot-wide circular solar arrays generated about 5,000 watt-hours of power per martian day at the start of the mission, enough to operate an electric oven for an hour and 40 minutes. A watt hour equals one watt of power flow over one hour.
Today, it's down to 500 watt-hours, or enough to run that same oven for about 10 minutes, thanks to a coating of martian dust deposited on the arrays over the past three-and-a-half years. While there's a possibility that winds from a passing dust devil might blow some of that dust off, engineers are not optimistic.
"Towards the end of summer of '22, we anticipate our seismometer will be turned off, not because we want to turn it off but unfortunately, we don't have the energy to run it," Garcia said. She said the team will use it intermittently after that as long as power is available, but by the end of the year the spacecraft is expected to fall silent.
"There really hasn't been too much doom and gloom on the team, we're really still focused on operating the spacecraft," Banerdt said. "We haven't had time to really reflect on what's coming up. I think that'll probably come later this summer."
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