Pranay Mishra reached down to the floor of his workspace and scooped up a handful of what on Earth might come closest to feeling Martian soil.
“This is actually unprocessed garnet,” he said, sifting the gray grains in the palm of his hand. Tiny ruby blobs caught the light. Mixed with diatomaceous earth, a fine powder of algae fossils often used by gardeners, the coarse gray stuff is a decent substitute for the density and texture of Martian dirt. The only difference is that nobody has to clean up on Mars.
“I tore three pairs of shoes working here,” said the JPL systems engineer, laughing. “He follows you home. It’s in your car, it’s in your house — it’s everywhere.”
More than 80 million kilometers away, a critical mass of actual Martian dust has blanketed the solar panels of NASA’s InSight lander, which has been studying the red planet’s crust, mantle, core and seismic activity since 2018. Because the solar panels are inoperative, the batteries cannot generate enough voltage to keep the spacecraft’s instruments online, prompting the lander to power itself down and officially end the mission, NASA announced Wednesday.
InSight was developed to take this route. And when it did, it spelled the end for ForeSight, Insight’s counterpart at the Jet Propulsion Laboratory in La Cañada Flintridge.
For the past four years, ForeSight has been stationed in a bed of artificial Martian soil the size of a suburban home’s driveway, and tilted at exactly the same angle as its distant doppelganger. Every move InSight has ever made has been tested hundreds of times or more on its terrestrial twin.
When InSight encountered problems on Mars, engineers ran ForeSight on Earth with a flurry of troubleshooting exercises. Balloons have been attached to mimic its weight in Martian gravity, and motion capture points attached to its frame to accurately measure its movements.
After InSight landed on Elysium Planitia six months after its launch, JPL engineers donned virtual reality goggles loaded with images the lander broadcast back of its immediate vicinity. They then got on their hands and knees and crawled around with garden tools to shape the earth in ForeSight’s habitat into a perfect replica of the landscape around its brother on Mars.
No one has seen InSight since it launched from what was then Vandenberg Air Force Base 4½ years ago. But ForeSight has been a constant work companion for the people tasked with making InSight a success.
Plans for the testbed began several years before InSight’s first launch date in 2016. NASA robotics engineer Ashitey Trebi-Ollennu led the design, a task he began by envisioning a completed spacecraft that would land on Martian soil.
“I see the lander on Mars,” said Trebi-Ollennu. “I visualize that and play it backwards. Which functionalities do I need?”
One of InSight’s main goals was to record seismic activity on Mars that could provide new insights into the planet’s internal structure. To do this, the lander had to deploy a basketball-sized seismometer sensitive enough to detect the movement of a single atom, and then place a shield over it to protect the instrument from the elements.
Ensuring that this sequence of events ran smoothly on Mars required countless iterations on Earth.
“My job is basically to stack two blindfolded Russian dolls 100 million miles away,” Trebi-Ollennu said.
Engineers used ForeSight to rehearse each step of the process hundreds – and sometimes thousands – of times, testing their technique under a range of simulated conditions.
They installed a series of overhead lights that bathed the test stand in a faint golden glow of a day on Mars, which receives less than half the sunlight as Earth. To check how the lander’s cameras would process sunlight — which is scattered differently than artificial light — they rolled ForeSight into the parking lot.
For all its triumphs, the ForeSight testbed has also been a place of frustration.
InSight was equipped with a thermal probe, nicknamed the “mole,” that would drill into the planet’s crust to measure internal heat. As engineers watched the lander’s video footage of its attempt to deploy the mole, they realized something was wrong: the 16-inch long ram pounded but got nowhere.
For 22 months, instrument systems engineer Troy Hudson led the troubleshooting effort. With the replica positioned at the same angle as its Martian counterpart, and with the Martian lights tuned to reproduce the conditions captured by InSight’s cameras, engineers went through myriad alternatives that could solve the mole’s problem.
They lifted ForeSight onto a platform and brought in an additional box of fake Martian dirt for the replica probe to burrow into. Again and again they tried alternative angles that might allow the mole to gain traction without damaging its delicate tether.
Ultimately, the soil beneath InSight’s probe turned out to be of a different density and texture than the planners anticipated, and the mole was never able to generate enough friction to dig more than a few inches. While that bit allowed scientists to study the thermal properties of the soil, they couldn’t get deep enough into the crust to measure the planet’s internal heat flux.
“My little piece of it didn’t quite do everything we wanted,” Hudson said, making InSight’s retirement bittersweet. “I was very emotionally involved in this mission.”
Whatever emotions InSight and Foresight evoke, practical aspects must come first. Now that the mission is over, the testbed will be dismantled and its parts offered to other teams at JPL to reuse for their own needs, Mishra said. Everything that is not claimed is put into storage.
Over on Mars, when the voltage in InSight’s batteries dropped below the critical threshold, the lander entered what its designers call “dead bus mode,” said Bruce Banerdt, the mission’s lead investigator. That status was confirmed after InSight failed to respond to routine communications signals from Earth on Sunday and again on Tuesday.
His computer is off. The electronics stopped working. But the circuitry that runs from the solar panels to the batteries – a relatively low-tech function that requires very little power – will continue to operate indefinitely, keeping the batteries charged just enough to bring InSight back to life should an unexpected one occur Force should come in and clean those solar panels.
In this scenario, the lander reboots and emits sporadic radio signals, heard by every other spacecraft communicating from Mars, as a specific pattern of low-pitched hiss alerting engineers on Earth to its renewed activity.
If all of these things happened – a possibility Banerdt estimates there is a 5% to 10% chance – InSight’s mission would resume.
“That would be cool,” said Banerdt. “Let me just say it as an understatement: That would be cool.”
But no attempt is made to revive ForeSight, which will be gone for good by then.
Although he’s been working with the testbed longer than anyone on the team, Trebi-Ollennu isn’t sentimental about his idea being disassembled and packaged.
“In our business, the hardware is disappearing. So my emotion is not for the hardware. It’s about the people I’ve worked with and the contributions they’ve made — their toil and sweat, the disagreements and agreements,” he said. “When I see this testbed, I see people.”
Others see a colleague logging off for the last time.
“This is the end of the chapter,” Mishra said, gazing fondly at the lander and its ever-present layer of fine gray dust. “It’s like a friend to me that I’ve worked with for so long.”
https://www.latimes.com/science/story/2022-12-20/nasa-mars-insight-mission-ending-foresight-twin-dismantled NASA’s Mars InSight lander is close to shutting down