Wow, that brings back memories. Inhibited Red Fuming Nitric Acid (IRFNA) is the one we used as an oxidizer for rockets.  UDMH was dangerous stuff too. One of our people got messed up in the brain from it.  He went into a grocery store and filled a cart beyond full of laundry detergent and kept going until the police took him a hospital. And I remember a hypergolic that our fire department pored out of a bottle, it ignited immediately with contact to the air.  It was like a bottle of fire.

IRFNA and UDMH kept me out of the infantrty. I got drafted and in a secure class in advaced infantry training the instructor got cocky and asked the class if anyone knew what type of fuel the Army Lance Missile used. I raised my hand, explained it to the class, then got picked up by the MP's on the way out of class. It was secret data back then and they wanted to know where I got that info. Fortunately it was a secured class, I got debriefed. I proceed to OCS and got assigned to Artillery OCS.

O2 and high explosives are like chemical relativity. Outside people's physical experience.

Gotta check out the video...

Yes, all on the right track. A mix of a hydrocarbon base (the dirtyand probably oily rat), and LOX (liquid oxygen) produces a very unstable substance similar to nitroglycerin. Any ignition source, even a physical shock can set it off. Most of the rats in the areaa were probwly coated in oil and other contaminates from crawling arund on outdoor test stands etc.

Anoither incudent with LOX occured when a LOX Truck delivery driver knocked a verty large open end wrench off the fender of his truck. Apparently there was a slight leak dripping from somewhere where the wrench must have hit the asphault. Boom, we never found the driver and only pieces of the truck. Extremely shock sensitive. They replaced all the truck unloading pads with concrete, and it got cleaned regularly. I found this: https://www.youtube.com/watch?v=lY_BM...

Doesn't take much energy to overcome the barrier with with pure O2. Probably just the thing hitting the wall, and a little event right there, spreading immediately. I'm just assuming based on Snezzy's example. Maybe there was oil on the wall or the rat, or some left over, poorly cleaned hypergolic's

I thought about that but I was wondering what the ignition source possibilities were.

I wonder why John Drury Clark didn't include that rat story in his famous book, "Ignition!"

Rocket science is inherently exciting, even if nothing goes wrong. Things sometimes DO go wrong, as we all know. The Soviet fuel choice of the hypergolic combination of red fuming nitric acid (RFNA) and unsymmetrical dimethylhydrazine (UDMH) contributed to the dreadful catastrophe at Baikonur in 1960.

Combustible carbon-compounds in the rat and oxygen

Trying to wrap my 80+ year old brain around what contributed to initiate the explosion. Please Illuminate me before I wear it out.

In the early 60's I worked at the Santa Susan Mountain test facility for Rocketdyne.  At lunch one day someone caught a rat and dipped it in liquid nitrogen, freezing it almost instantly.  They then threw the rat against a wall, and it just completely shattered like it was made of crystal.  The practice continued for a while, until someone at Rocketdyne's facility at Edwards AF Base in the desert did the same thing.  The problem was that they dipped their rat into liquid oxygen.  When thrown against the wall of a building, it blew a hole in the wall "big enough to drive a Mac Truck through".  The practice ceased right then and there.  Experience is still the best teacher (except of course, in politics).

Yah, it makes the vehicle lighter. (that's was intenend to be a joke). But in actuallity it is also true.

As I wrote above, weight shouldn't be the only consideration.

Weight

As someone who trains the rocket engineers, I have to understand, and for me to provide value for value exchange to them, I need to get them to understand. As to the decisions regarding fuel technology, just because a fuel is lighter doesn't mean that it is the best decision.

Because it has a lower boiling point than nitrogen, doesn't freeze near absolute zero degrees.

It's rocket surgery. We're not supposed to understand. I did poke around on the NASA website to see if there were any tech details; found nothing. Do we know what trail of decisions led to the choice of fuel technology?

Why use valuable Helium to pressurize the fuel and oxidants, vs something easy like Nitrogen?

Cryogenic embrittlement is a surprisingly big problem. A part of my job is to make sure the engineers know what all the potential rocketry issues could be ... and to troubleshoot proactively.

Liquid helium and liquid hydrogen are much colder than liquefied methane that SpaceX uses. Is it any wonder that SpaceX is more reliable?

If a comparison were made of the IQ of NASA engineers on this program vs the engineers on
the Apollo program, would the DEI of NASA's Artemis program be exposed as deficient?
And what would the contract awards on the Artemis program show ?

Better to catch these problems before launch even if it is disappointing.

Interesting line in the article: "Artemis 2 will send three NASA astronauts and one Canadian on a roughly 10-day trip around the moon and back to Earth in a Orion capsule." /s The terms America or Americans isn't mentioned once in the article so exactly who are those "NASA astronauts"?