The Mars Mission That Faced Unforeseen Challenges
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Exploring the Mysteries of Mars
NASA's relentless pursuit of Martian exploration hit a snag with its InSight mission. The agency spent almost two years trying to maneuver a probe, intended to penetrate the planet's surface, which ultimately proved more difficult than anticipated.
By Marina Koren
Troy Hudson had hoped to take a break from thinking about Mars during the holiday season. However, given his deep connection to the planet—symbolized by a tattoo on his arm—and his decade-long involvement with a robotic mission currently stationed there, he found it hard to escape thoughts of Mars. NASA was nearing a critical decision point regarding the future of the InSight probe.
Hudson is part of the engineering team at NASA's Jet Propulsion Laboratory (JPL), focusing on the InSight mission, which successfully landed a probe on Mars in late 2018. One of its key instruments, a spike-shaped device known as the "mole," struggled for nearly two years to penetrate the Martian soil. Throughout this challenging period, the team held onto hope, characteristic of NASA's history of overcoming odds, especially in Martian exploration.
The mole was designed to delve deeper into Martian soil than any previous machine, aiming to measure the planet's internal heat—a cosmic thermostat of sorts. Unfortunately, the team faced repeated setbacks. As the holidays approached, they had already programmed a final effort for January, leaving Hudson and his colleagues in a state of anxious anticipation.
Earlier this month, the mole attempted to penetrate the soil, but progress was minimal. Initially, the team expected the probe to reach a depth of approximately 16 feet (5 meters), but it only managed around 16 inches (40 centimeters). Consequently, NASA decided to conclude the mole's work, while the overall InSight mission continues.
"It's a significant disappointment," remarked Sue Smrekar, the deputy principal investigator for the InSight mission at JPL. Some Mars missions turn out to be resounding successes, providing humanity with insights into a distant world. Others, however, resemble a robotic vacuum stuck in a corner, far from its intended path.
Mars: A World Once Like Ours
A few billion years ago, Mars resembled Earth, boasting a thick atmosphere and bodies of water. However, the two planets diverged significantly over time. While Earth nurtured a vibrant ecosystem, Mars transformed into a cold, desolate landscape.
The InSight mission was conceived to uncover Mars's geological history and the forces at play in shaping rocky planets. The mole was crafted to drive itself into the ground, trailing a tether equipped with sensors. The site selected for landing met typical criteria for Mars missions: flat and devoid of obstructions. Geologists analyzed data from orbiting spacecraft and other missions to choose a location anticipated to have fine soil ideal for the mole's operation.
When the mole began its hammering efforts in the winter of 2019, the team at JPL eagerly awaited updates from Mars. They hoped to receive data indicating the probe had made significant progress underground. Instead, they were met with the surprising revelation that the mole had gone nowhere.
The initial hypothesis was whether the mole had struck a rock or sustained damage. The team directed the probe to persist, monitoring its progress after each series of hammer strikes. Hudson recalled the frantic early months, as numerous potential issues loomed.
The root cause turned out to be the soil itself. The team had anticipated that loose soil would collapse around the mole, providing the necessary friction for it to continue. Instead, the Martian soil proved sticky, clumping together and creating voids around the probe. "It's like trying to hammer a nail into a wall without any grip," explained Tilman Spohn, the principal investigator for the mole experiment at the German Aerospace Center, which collaborated with NASA on this project.
Prior to the mission's launch, engineers had tested the mole in various soil conditions. They noted that it struggled in stickier soils, especially under Martian atmospheric conditions. However, with time constraints, they opted not to make significant design changes, believing the chances of success remained high.
Adapting to Challenges
Following the initial setback, the team attempted several unplanned strategies to encourage the mole to function. The rover's robotic arm tried to cover the mole with soil and applied downward pressure. Meanwhile, the mission's seismometer monitored the vibrations generated by the mole's attempts to hammer down. It was a slow and tedious process. Each small advancement was celebrated, while every setback was met with despair. "Every time we did something on Mars, the anticipation was palpable—did it work?" recalled Khaled Ali, an engineer at JPL.
By the previous fall, the team had managed to get the mole partially buried, but the sticky soil issue persisted, and the robotic arm could no longer assist. "If you could lift the soil around InSight and just wiggle your hand slightly, it would probably crumble," commented Nick Warner, a geologist involved in selecting the landing site. That stickiness ultimately hindered the mole's mission.
Despite the challenges faced, engineers and scientists regarded the mission as a partial success. Thanks to the mole, they have uncovered unexpected insights about the Martian landscape. Learning something new is deemed better than learning nothing at all. Warner and others believe the soil contains salts acting like cement, a finding they did not anticipate but recognized from other Martian regions. Engineers understood the risks involved with the mole's mission—predicting extraterrestrial conditions is a formidable task, and adapting when those conditions diverge from expectations is even more challenging.
Although NASA has officially ended the mole's mission, InSight's overall mission has been extended until late 2022, focusing on recording seismic activity from deep within Mars. A new NASA rover, Perseverance, is set to launch shortly. While the imagery of one spacecraft assisting another is appealing, Perseverance is not designed to aid InSight and will explore a different area, searching for signs of past life in Martian soil using previously tested drilling technology.
Chapter 2: The Challenges of Martian Soil
This first video discusses the high failure rate of Mars missions and the complexities involved in successfully exploring the red planet.
The second video highlights NASA's recent discovery by the Mars rover, emphasizing the unexpected findings that continue to shape our understanding of Mars.