NASA’s Artemis 2 lunar mission will put its astronauts in danger – but how much danger is hard to say.
The agency announced Thursday (March 12) that it is aim for 1 April for the launch of Artemis 2which will send four astronauts on a 10-day round trip the moon and back to earth.
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“I actually wouldn’t put a number on it,” said Lori Glaze, acting assistant administrator for NASA’s Exploration Systems Development Mission Directorate, during a briefing Thursday (March 12) following the completion of the Artemis 2 flight readiness review.
Reporters repeatedly pressed Glaze and John Honeycutt, head of the Artemis 2 mission command, for numbers during this briefing. And a few came up.
For example, Honeycutt noted that historically new rockets have successfully launched on their debut flights about 50% of the time. So maybe that was the expectation Artemis 1the first flight of the Artemis program Space Launch System (SLS) rocket. (Artemis 1 was a success, sending an unmanned Orion capsule to lunar orbit and back in late 2022.)
Human spaceflight programs that launch regularly can probably expect a failure rate of about 2% — 1 in 50 — on their second or third lift, Honeycutt added. But Artemis’ cadence isn’t exactly regular, given that there will be about a 3.5-year gap between the first and second missions if Artemis 2 actually gets off track in early April.
“That basically means we’re probably not 1 in 50 on the mission going exactly as we want, but we’re probably not 1 in 2 like we were on the first flight,” Honeycutt said.
“That’s what I want to tell you,” he added. “I think we’re being very careful not to put probable numbers on the table for this mission, just given the small amount of data.”
The range Honeycutt cites matches figures recently released by the NASA Office of Inspector General (OIG), in a report on NASA’s handling of Artemis Human Landing System Contracts – awards given to SpaceX and Blue origin to develop and operate manned lunar landers for the program.
IN the reportposted online Tuesday (March 12), the OIG estimated that there is a 1-in-30 risk of failure overall during a manned Artemis mission to the lunar surface, and a 1-in-40 risk during the lunar operations phase.
The OIG report also puts this risk threshold into context, comparing it to other NASA space programs. For example, the relevant figure is 1 in 200 for a 210-day commercial crew mission to The International Space Station — that is, one flown by SpaceX with its Falcon 9 rocket and Dragon capsule. (Boeing also has a NASA commercial crew contract, but has yet to fly an operational astronaut flight to the orbiting laboratory.)
The risk of loss of crew during Apollo lunar missions was a pretty terrifying 1 in 10, according to the OIG report. And the leaders of NASA space shuttle program, which flew from 1981 to 2011, “believed they were operating at a 1 in 100 threshold for crew losses, but years later determined the actual number was 1 in 10 for the early flights,” the OIG report said.
Honeycutt’s reluctance to put a hard number on the Artemis 2 risk therefore makes a lot of sense. As the example from the space shuttle days shows, estimates made using scarce data are likely to be imprecise and need future revision.
There are other complications as well, which are related to the relatively small sample sizes and variety of hazards involved in human spaceflight.
“We’ve been tracking mission losses, crew type losses, but I’m not sure we understand what they mean,” Honeycutt said.
As an example, he explained that the agency’s modeling work identifies micrometeors and orbital debris (MMOD) as the single greatest risk to human spaceflight.
“It’s real, right? But when did the last two bad events happen? Go uphill, in the highly energetic event,” Honeycutt said, presumably referring to the space shuttle Challenging and Columbia accidents in 1986 and 2003 respectively, which killed a total of 14 astronauts. (Challenger exploded 73 seconds after liftoff, and Columbia broke apart during reentry due to damage to the orbiter during liftoff.)
“So, you know, we can sometimes trick ourselves into thinking, ‘Really? Is that the biggest risk to the mission — MMOD?'” he said.
Honeycutt seemed to realize that such admissions, valid and honest as they are, would likely spawn stories like the one you’re reading now. “Well, this should make for some good reading for the next few days,” he said with a smile, drawing laughter from the reporters in the room.
