In February, NASA celebrated the arrival of the first US-made lander on the Moon in more than 50 years, an achievement that helps pave the way for the return of American astronauts to the lunar surface later this decade. But the clock was ticking for Intuitive Machines' Odysseus spacecraft after touching down on February 22 near the Moon's south pole.
Each day and night on the Moon lasts two weeks. When the Sun sets, a solar-powered lunar lander like Odysseus is starved of energy. Temperatures during the lunar night plummet, bottoming out at around minus 280° Fahrenheit (minus 173° Celsius).
Over the course of two weeks, these cold temperatures can damage sensitive spacecraft equipment, killing a lander even if it could start generating power again at lunar sunrise. Surviving the night requires heat and electricity, and NASA officials say nuclear power is one of the most attractive solutions to this problem.
Freezing to death
“We do anticipate having to deploy nuclear systems on the lunar surface," said Jay Jenkins, program executive for NASA's Commercial Lunar Payload Services (CLPS) program.
"Honestly, it’s not unrealistic that we’ll want to do be able to do this within five years or less. We are starting to buy payloads that are meant for investigations that go beyond one lunar day," Jenkins said during a Nuclear Regulatory Commission conference earlier this month.
The commercial Odysseus lander was part of CLPS. Intuitive Machines had a $118 million contract with NASA to deliver science and tech demo payloads to the lunar surface.
As expected, Intuitive Machines declared the end of the Odysseus mission last month when ground teams confirmed that the lander did not make it through the night. Just in case it woke up, engineers tried listening for a signal from the spacecraft, nicknamed Odie, but didn't hear back.
"This confirms that Odie has permanently faded after cementing its legacy into history as the first commercial lunar lander to land on the Moon," Intuitive Machines posted on X.
“Because of the extreme temperatures through the lunar night, typically, you don’t come back to life," said Peter McGrath, chief operating officer of Intuitive Machines, before the launch of Odysseus last month. "The batteries don’t survive, the boards crack on the computers and the avionics boxes, and even though you may be able to collect power through the solar arrays, you really don’t have anything that functions, so we’ve been looking at how to keep landers alive.”
India's Chandrayaan 3 lander also didn't make it past its first lunar day after it arrived on the Moon last August. There are exceptions, though. Japan's SLIM lander touched down on the Moon in January and is still alive, even though Japanese engineers expected it would succumb to cold temperatures during its first lunar night. Japan's space agency said some temperature sensors and unused battery cells on SLIM are starting to malfunction, but the "majority of functions" have survived so far.
The first phase of America's return to the Moon, initially consisting of robotic commercial missions and then larger human-rated landers, will have the same limitations as Odysseus. The next series of commercial landers set to launch to the Moon under contract with NASA are all designed to operate for one lunar day. The first human landing on the Moon under NASA's Artemis program, Artemis III, will spend up to six days on the lunar surface. The astronauts won't stay the night.
Intuitive Machines
NASA's long-term goal is to build a sustainable presence on the lunar surface. Mission lifetimes of one or two weeks won't cut it for a Moon base.
"Right now, all the CLPS deliveries basically land at lunar morning and they end at lunar evening," Jenkins said. "That’s very very limiting, especially for experiments that we would like to go for a very long time, for months or years, in order to monitor geophysical properties, or in order to monitor various other aspects of the Moon."
NASA also wants to venture into permanently shadowed craters at the Moon's south pole. The bottoms of these craters haven't seen sunlight for billions of years, and observations from orbit suggest these cold traps harbor water ice, a valuable resource for future lunar explorers.
“So survive-the-night capability, or STN, is very highly desirable," Jenkins said.