A U.S. business and the next generation of moonbound spacefarers are learning that landing upright on the lunar surface is much harder than it looks.
Intuitive Machines’ spacecraft took this selfie, pictured above, about 35 seconds after tipping over during its descent on Feb. 22. Because the lander is on its side, the mission will be forced to end prematurely. Flight controllers based in Houston plan to continue collecting data from the lander until its solar panels no longer receive sunlight, according to a company post on X, formerly Twitter.
Based on the positions of Earth and the moon, they’ll probably lose contact with their lander, dubbed Odysseus, on Tuesday.
While some observers have criticized how “successful” this landing attempt should be considered — NASA administrator Bill Nelson was quick to say the Houston-based space contractor had “aced” the landing last week — scientists are reminding the public why this keeps happening. Japan’s own lander also made it to the lunar surface last month, but with its thruster end pointing up.
“When a lander is tipping, inertial forces push it over, while gravity pulls its feet back down flat. On the Moon, gravity is reduced by a factor of 6, but inertial forces are not. *Everything is 6 times tippier on the Moon*,” wrote Phil Metzger, a planetary physicist at the University of Central Florida, in an X post. “You *must* plan to reduce inertial forces by a factor of SIX lower than how your hardware operates on Earth if you want things to be as stable on the Moon as they are on the Earth.”
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When Odysseus landed sideways, some of its antennas were blocked, weakening the communication signal. If all had gone as planned, though, the mission would have lasted only a few days longer, when the two-week “lunar night” will fall.
Intuitive Machines’ mission is the first commercial uncrewed lunar landing. The unprecedented achievement is a win for NASA, which has invested $2.6 billion in contracts with the company and several other vendors to deliver instruments to the moon over the next four years.
“Everything is 6 times tippier on the Moon.”
Even after all these years, landing on the moon is still difficult. The lunar exosphere provides virtually no drag to slow a spacecraft down as it approaches the ground. Furthermore, there are no GPS systems on the moon to help guide a craft to its landing spot. Engineers have to compensate for these shortcomings from a quarter-million miles away.
A last-minute crisis almost ruined the landing. Intuitive Machines discovered a problem with its navigation system just a few hours before touchdown. Flight controllers opted to take another lap around the moon, which bought them extra time to switch to a NASA laser-based system that was on the spacecraft as an experiment. The backup NASA system worked quite well.
Intuitive Machines’ Odysseus lander snaps a wide view of Schomberger crater on the moon on Feb. 22, 2024.
Credit: Intuitive Machines
Odysseus arrived within a mile of its landing target near Malapert A crater, about 200 miles from the lunar south pole. Many nations and private ventures have set their sights on the region because of its ice, thought to be buried in the polar craters. The natural resource is coveted because it could supply drinking water, air, and rocket fuel for future missions, ushering a new era in spaceflight.
Despite the flaws in the flight, its success bolsters confidence in NASA’s Commercial Lunar Payload Services initiative (CLPS), a private sector recruitment program to support the agency’s lunar ambitions. Through several contracts, the agency wants to establish regular lunar missions to prepare for putting Artemis astronauts on the moon in 2026 or later.
