NASA’s InSight spacecraft isn’t quite dead yet.
But InSight, a stationary robotic probe on Mars, has grown steadily weaker as dust accumulates on its solar panels. Mission officials predict that by the end of the summer it will not have enough energy to continue operating its instruments and by the end of the year it will become silent.
“It’s just due to the lack of energy,” Kathya Zamora Garcia, the mission’s assistant project scientist, told a news conference on Tuesday.
The spacecraft could prove lucky if a dust devil – a miniature whirlwind swirling along the Martian landscape – passed by and blew the dust off the solar panels. Although several thousand dust devils were detected in the area, none usefully cleared InSight.
“We’re not too hopeful considering it’s been three and a half years and we haven’t seen any yet,” said InSight principal investigator Bruce Banerdt, “but it could still happen.”
When InSight landed in November 2018, its pristine solar panels generated 5,000 watt-hours of power every Martian day. Today, shrouded in dust, they produce a tenth.
The spacecraft completed its primary objectives during its two-year primary mission; NASA then approved a two-year extension until the end of 2022.
As the energy wanes, officials will begin shutting down the spacecraft’s instruments and stowing its mechanical arm. They’ll try to run the craft’s main scientific tool, a sensitive seismometer, for as long as possible, although in a few weeks they’ll start running it for only part of the day, or maybe even both. days, instead of continuously .
Ms Garcia said the seismometer is likely to be completely shut down by July. After that, there will be just enough power to check radio communications and maybe take the occasional photo.
Once InSight loses its power, it will join an assortment of NASA missions stuck on the Red Planet after long and successful runs, including the two Viking landers that touched down in 1976 and the Spirit and Opportunity rovers that arrived in 2004 for 90-day missions, but lasted for years. NASA still has two more rovers and an experimental helicopter studying the Martian surface, and China has a rover in operation there.
Most NASA missions to Mars over the past two decades have focused on the possibility that the fourth planet from the sun could have been hospitable to life.
InSight – the name is a compression of the mission’s full name, Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport – was a diversion, focusing instead on the mysteries of Mars’ deep interior. The $830 million mission aimed to answer questions about the structure, composition and geological history of the planet.
Mars lacks plate tectonics, the shifting of pieces of the crust that shapes our planet’s surface. But marsquakes do happen nonetheless, driven by other tectonic stresses like the crust shrinking and cracking as it cools.
During its mission, InSight recorded more than 1,300 marsquakes. Just two weeks ago, it observed the largest earthquake to date: a magnitude of 5.0, modest by Earth standards, but at the high end of what scientists expected from Mars.
The epicenter of the 5.0 magnitude quake was near a series of fissures known as the Cerberus Fossae, where many of the earthquakes detected earlier had occurred, Dr Banerdt said. But, he added, “It’s not really in Cerberus Fossae, which is interesting. And we don’t really understand it yet.
He said scientists only had two weeks to analyze the data, but they could clearly see the seismic signals, and the quake could have been large enough to cause Mars to vibrate like a bell, although only at frequencies too low to be heard.
“This earthquake is really going to be a treasure trove of scientific information when we sink our teeth into it,” Dr Banerdt said.
By listening to the echoes of seismic waves bouncing around inside Mars, InSight produced data that could be turned into a three-dimensional map of the planet.
The crust turned out to be thinner than expected and appears to consist of three sub-layers. Seismic signals also measured the size of the core: about 2,300 miles in diameter.
The seismometer revealed not only what lay below, but also the dynamics of the air above. Winds blowing between 10 and 15 miles per hour off InSight’s solar panels caused the spacecraft to vibrate, and the spacecraft recorded the vibrations, which were turned into sound.
InSight’s other primary instrument, a thermal probe that was expected to hammer about 16 feet into Martian soil, failed to fully deploy.
Despite two years of effort, the instrument, nicknamed the “mole”, never descended more than an inch below the surface. The soil where it landed had a tendency to clump together, a different property from materials found elsewhere on Mars. Clumping reduced the surface of dirt pressed against the sides of the mole, and with insufficient friction it was unable to hammer down.
“It turned out that the particular ground that was under InSight when we landed had a consolidated layer of crusty soil at the very top,” Dr Banerdt said. “And that scab, the ground kind of disintegrated when the mole tried to get in.”
Without the mole traveling underground, scientists didn’t get the hoped-for measurements of the heat exiting the planet, which would have revealed more accurate data on Mars’ interior temperatures today and the energy at the origin of geological processes.
“That’s what we lost,” Dr. Banerdt said.
Even after InSight’s silence, there will remain a possibility that a passing dust devil could sweep away the solar arrays and the spacecraft could revive.
“We’re going to listen,” Ms. Garcia said. “And once we get a few beeps, if it happens again, if there’s a natural cleanup, we’ll assess if there’s enough energy to get the lander working again.”
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