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| NASA's InSight Mars lander died from dust overload. (Image credit: NASA/JPL-Caltech) |
Last week, the NASA Mars InSight lander suffered a slow death from dust. The robot's 25 square feet (4.2 square meters) solar power array slowly dissolved beneath a thick layer of dust over the course of months as it was designed to monitor the tectonic activity on Mars. After receiving no communication with the lander for days, NASA declared the mission to be lost on Wednesday (Dec. 21).
InSight's mission lasted longer than predicted by two years when it landed in the flat, uninspiring Elysium Planitia basin south of Mars' equator in November 2018. However, many questioned if there was anything that could have been done to preserve the robot, which was otherwise in excellent condition and was producing ground-breaking research about the life on Mars.
Cost versus benefit
About six weeks before to InSight's death, NASA discussed the trade-offs that engineers had to make while planning a mission for the extremely dusty planet Mars in a Twitter conversation (opens in new tab).
"Do I not have a means of dusting myself off (wiper, blower, etc.)? is a common question. It's a good question, and the quick response is as follows: "NASA posted something on the lander's Twitter feed. "Such a system would have increased weight, complexity, and expense. Bringing solar panels large enough to power my whole expedition was the easiest and most affordable method to achieve my objectives, which they accomplished (and then some!)."
Dust storm season
Space organizations often strive to steer clear of Mars' dust storm season, which occurs throughout the planet's northern autumn and winter seasons. Since a year on Mars is roughly equivalent to two Earth years, most recent rovers and landers, including InSight, have survived several seasons of dust storms. The Curiosity rover, which is still operating well after 11 years on Mars, has seen quite a few seasons of dust storms. Even the quantity of dust that gathered on the rover's sensors and deck was measured (opens in new tab), demonstrating how seasonal winds and dust devils prolong the life of rovers. It turns out that InSight was not very fortunate when it came to Mars' natural cleaning agent.
No dust devil car wash
Spirit and Opportunity, two of NASA's elder Mars rovers, have been notably witnessed being cleaned by dust devils. Particularly Opportunity, which was able to outlive its intended three-month lifespan several times, was able to carry out its job for more than 14 years. Regular dust devil sweeps and wind-driven cleaning activities were crucial to the success of that world-record mission. A massive dust storm eventually defeated the little rover in 2019, bringing an end to its record-breaking exploration trip.
InSight seems to have been in a "particularly unfavorable position for dust removal," according to Mike Williams, Chief Engineer at Airbus Defence and Space, which is presently revising the dust defense strategy for the European ExoMars Rosalind Franklin rover.
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| NASA's InSight lander lost power because of dust covering its solar panels. (Image credit: NASA) |
Tilting solar panels
Williams concurs that NASA's strategy of using large solar panels is the best, safest, and most affordable way to protect Mars-exploring spacecraft from dust. Airbus, though, is considering whether to include a specialized dust protection capability, and they have plenty of time to do so. The mission, which was developed in conjunction with Russia, was put on hold after Russia's invasion of Ukraine. Airbus is now keeping the ExoMars rover in a clean room while replacing certain crucial parts that were initially manufactured by Russia since the scheduled September launch was scrapped.
The best and most straightforward answer, according to Williams, is to size the arrays to be able to handle the decreased quantity of sunlight that will reach them as a result of the dust. "The least difficult level is this one. It has the lowest risk since it needs the fewest subsystems and functions. That approach is unquestionably the most ideal one from the standpoint of mission design."
According to Williams, engineers looked at a wide range of dust-cleaning devices while planning the ExoMars mission, including brushes, wipers, gas blowers, and electrostatic wipers. At that time, they concluded the rover didn't need to self-clean. Its initial mission in Oxia Planum was only intended to last 180 sols on Mars. They are reconsidering their strategy once again since the revised launch date is now predicted to occur no sooner than in 2028.
We are considering perhaps restoring some of that capabilities now that ExoMars has been revived, Williams added. "We may be able to move some of the dust using a technique like tilting solar panels. Additionally, it would make it easier to direct the solar panels toward the sun, which would potentially have some advantages."
Williams noted that Airbus engineers, like NASA's, must accept the possibility that ExoMars, like earlier Martian spacecraft, may ultimately perish from dust and won't be unhappy if the rover just slightly outlives its intended mission lifespan. However, they anticipate receiving some assistance from Martian weather, similar to Spirit and Opportunity.
Williams stated, "Unfortunately, that's simply the way it is with space missions.
InSight's self-cleaning attempt
Even though InSight wasn't designed to clean itself of dust, NASA made some desperate measures to assist the lander in its closing months as the power produced by its solar panels began to decline.
In May, InSight's robotic arm was given the order to scatter some sand over one of the lander's dust-covered panels by ground controllers. The sun-blocking dust layer actually became thinner as the wind moved the sand grains over the panel because they picked up part of the dust along the way.
According to a NASA release, the procedure allowed the lander to gather about 30 watt-hours of energy every sol at the time (opens in new tab).
Nature triumphed in the end. the same as always. And InSight surely didn't surrender easily.
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