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Science

OKIsItJustMe

(22,205 posts)

12. We both realize that (I was even repeating myself)

Reply to eppur_se_muova (Reply #10)

Sat May 16, 2026, 04:28 PM

May 16

I just didn’t want the casual reader confusing the two. While both projects (NERVA and Orion) started at (roughly) the same time, Orion was absurd, and NERVA (much more) practical. NERVA-style engines were built and tested.

https://www.nasa.gov/rocket-systems-area-nuclear-rockets/

I keep imagining astronauts sitting atop a rocket being thrust into space by a series of powerful explosions, the ride was quite rough enough on conventional engines. (Presumably, they would have had some immense "shock absorbers” to cushion them from the blasts… The structural metal required to hold the rocket together would have added so much mass…)

They might as well have fired them from a giant cannon!

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NASA Fires Up Powerful Lithium-Fed Thruster for Trips to Mars [View all] OKIsItJustMe May 15 OP

Another fucking waste of money. 3Hotdogs May 16 #1

Previous ion engines have favored very heavy atoms as propellant -- mercury or xenon. More atomic mass -- eppur_se_muova May 16 #2

The NERVA engine used hydrogen, so (you know) lithium is heavier than that, but certainly lighter than mercury OKIsItJustMe May 16 #4

Hydrogen is being used there as ejectable mass, nothing more. It's handled by mechanical pumps and pressure. eppur_se_muova May 16 #5

Check out the NASA paper I added to the bottom of the reply OKIsItJustMe May 16 #6

Thanks for the paper. I knew about the older nuclear interest. eppur_se_muova May 16 #7

NERVA was not the same as Orion OKIsItJustMe May 16 #8

Yes, I know that, thank you. In fact you're just repeating things I've already said in my replies. nt eppur_se_muova May 16 #10

We both realize that (I was even repeating myself) OKIsItJustMe May 16 #12

Ah, OK ... writing for a larger audience ... eppur_se_muova May 16 #14

I've been watching "For All Mankind" on Apple TV OKIsItJustMe May 16 #15

Isn't lithium in somewhat short supply? erronis May 16 #3

Meanwhile, at a grossly overspent under intellectual trump supported SpaceX 3825-87867 May 16 #9

NASA is facing serious cuts OKIsItJustMe May 16 #11

More from the paper cited by OKIsItJustMe .... eppur_se_muova May 16 #13

"It must have been a real pleasure to work out the mathematics of MPD for the first time..." OKIsItJustMe May 16 #16