During the Artemis II launch, people were shocked when I told them the official survivability threshold SpaceX’s Dragon had to meet to fly under Commercial Crew & Cargo Program (C3P),
Requirement 5.2.2 – The [Commercial Crew Transport System] shall safely execute the Loss of Crew (LOC) requirements specific to the NASA Design Reference Mission (DRM). The Programs shall determine and document the LOC risk when DRMs are specified. The following are current:
a) The LOC probability distribution for the ascent phase of a 210 day ISS mission shall have a mean value no greater than 1 in 1000
b) The LOC probability distribution for the entry phase of a 210 day ISS mission shall have a mean value no greater than 1 in 1000
c) The [overall] LOC probability distribution for a 210 day ISS mission shall have a mean value no greater than 1 in 270
– Commercial Crew Transportation System Certification Requirements for NASA Low Earth Orbit Missions ESMD-CCTSCR-12.10 Revision-Basic. accessible here.
Loss of Crew is a polite way of saying that everyone on board dies. Put differently, the requirements officially state that it is taken as acceptable / par for the course if,
-
All astronauts on Dragon die on ascent or descent 1 out of 1,000 times.
-
Everyone dies 1 out of 270 times.
There isn’t a formal acceptable LoC specification for Artemis, but according to NASA’s Inspector General,
[after analysing] the risk of failures in Starship’s avionics, main engines, lander propulsion, landing legs, and electrical power. [NASA]’s loss of crew threshold is 1 in 40 for lunar operations and 1 in 30 for the Artemis missions overall.
– NASA Office of Inspector General. NASA’s Management of the Human Landing System Contracts. IG-26-004, 10 Mar. 2026. accessible here
Pre-launch, well-meaning people across multiple forums were talking about NASA’s “broken safety culture [..since] the beginning of the Shuttle program.” As these commentators have pointed out, there’s reason to believe Orion’s heat shield might be compromised.
Pre-launch, SLS was leakier than a submarine’s screen door; had a battery failure in its launch abort system; had multiple NOGO points. But they launched anyway.
As they should have.
but what about apollo?
Our memories of Apollo are hazy due to decades of hagiography. There’s a reason why there wasn’t an Apollo 18, or 19 and 20. Even though funding had been secured, an executive decision was made to kill the program early, because LoC was inevitable.
To quote, the astronaut’s astronaut John Young,
As Young was training to command his own 1972 landing mission, his new wife told him something disturbing. She had learned about a formal risk analysis that put the chance of survival on future moon missions as low as 20 percent. Young claims it didn’t affect his thinking, but it was upsetting to his wife, and apparently to NASA. “George Low never let anybody see those numbers,” Young says today. Low was the space agency’s deputy director at the time. “I really believe that’s why the big guys wanted to knock off [Apollo] 18, 19, and 20 [the later missions that were canceled in 1970]. Even if they’d had the money, they didn’t see the benefits of lunar surface exploration, in terms of real scientific benefits, but they thought they were going to lose some people. You know, they might have.”
— astronaut John Young, as quoted in, “John Young, Spaceman. ” accessible here.
Every Apollo mission was on the edge. No mission was problem free.
The one most comparable to Artemis II? Apollo 8? Foggy windows. Helium bubble in the oxidizer line. An engine with “a small chance of [exploding].” Accidental computer wipes. Navigation loss (due to said computer wipe). Flipping over in the ocean. And a stuck hatch.1
Testing [..had] shown that the service propulsion system (SPS) engine had a small chance of exploding when burned for long periods unless its combustion chamber was “coated” first by burning the engine for a short period. This first correction burn [..added] less [..velocity..] than [planned,] because of a bubble of helium in the oxidizer lines, which caused unexpectedly low propellant pressure. The crew had to use the small RCS thrusters to make up the shortfall. Two later planned mid-course corrections were canceled because the Apollo 8 trajectory was found to be perfect.
– via wikipedia. Apollo 8 – Lunar Trajectory.
The first humans to truly leave Earth ended their heroic2 journey bobbing, upside down, in vomit.
The next one? 9? The LEM failed to jettison. Faulty ullage burn… Every single Apollo, Gemini, and Mercury flight had an “oh shit” moment. Giving ammunition to the many, many, many critics, congressmen, and senators who wanted to end the program.
It took $257 billion and the superhuman competence, diligence, and effort of four hundred thousand people to make sure only 3 astronauts died.3 And they still barely made it.
Their effort – their sacrifice – are why we remember Apollo. It’s why it was such a leap ahead. And it’s why no one has done it since. via ‘NASA’s Understanding of Risk in Apollo and Shuttle,’
In abstract, everyone is OK with “taking risks,” but very few people are able to stomach real risk.
We live in a world that’s – for the most part – overwhelmingly safe. Parts in our planes are rated to 1 in a Billion failure rates.4 Water contamination is measured in parts per billion.5 Deaths from infectious disease have gone from the leading cause of death to relatively rare.6 Violence keeps getting rarer with time.7 More people die from obesity than starvation.8
It took centuries for humans to learn enough about this unsafe world to invent the technologies necessary to make it safe. We haven’t done that yet for space – not even near-Earth space. For most in the developed world,9 Artemis is the first time they’ve encountered real risk. And that’s OK.
It’s what makes exploration worth it.
Capt. John Young [..put] it this way: ‘You put some people on top of four million pounds of high explosives, you light the fuse, and in eight and a half minutes they are going eight times faster than a rifle bullet. What part of that sounds safe to you?’
putting in a subscribe button so that substack stops bugging me
Apollo 8 was the second crewed flight since the Apollo 1 fire. Grissom, White and Chaffee burned to death trying to open the hatch. I know the official cause of death is “smoke inhalation,” but they died in under a minute. Given photos of the capsule… more here.
Given the unknowns, they truly are heroes.
Adding training accidents, 10 astronauts died during the 1960s. One worker, William B. Estes, died due to an accident on the pad.
Federal Aviation Administration. “System Design and Analysis.” Advisory Circular 25.1309-1A. Washington, DC: FAA, 1988. accessible here.
United States Environmental Protection Agency. “National Primary Drinking Water Regulations.” EPA. accessible here.
Centers for Disease Control and Prevention. “Achievements in Public Health, 1900–1999: Control of Infectious Diseases.” Morbidity and Mortality Weekly Report 48, no. 29 (1999): 621–629. accessible here.
Roser, Max, Hannah Ritchie, Fiona Spooner, and Bastian Herre. “Homicides.” Our World in Data, 2024.
Popkin, Barry M. “The World Is Fat.” Scientific American 297, no. 3 (September 2007): 88–95. accessible here.
I am excluding combat.