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Science

OKIsItJustMe

(22,089 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

8 hrs ago

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 Friday OP

Another fucking waste of money. 3Hotdogs Yesterday #1

Previous ion engines have favored very heavy atoms as propellant -- mercury or xenon. More atomic mass -- eppur_se_muova 22 hrs ago #2

The NERVA engine used hydrogen, so (you know) lithium is heavier than that, but certainly lighter than mercury OKIsItJustMe 13 hrs ago #4

Hydrogen is being used there as ejectable mass, nothing more. It's handled by mechanical pumps and pressure. eppur_se_muova 12 hrs ago #5

Check out the NASA paper I added to the bottom of the reply OKIsItJustMe 12 hrs ago #6

Thanks for the paper. I knew about the older nuclear interest. eppur_se_muova 11 hrs ago #7

NERVA was not the same as Orion OKIsItJustMe 10 hrs ago #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 8 hrs ago #10

We both realize that (I was even repeating myself) OKIsItJustMe 8 hrs ago #12

Ah, OK ... writing for a larger audience ... eppur_se_muova 6 hrs ago #14

I've been watching "For All Mankind" on Apple TV OKIsItJustMe 6 hrs ago #15

Isn't lithium in somewhat short supply? erronis 14 hrs ago #3

Meanwhile, at a grossly overspent under intellectual trump supported SpaceX 3825-87867 8 hrs ago #9

NASA is facing serious cuts OKIsItJustMe 8 hrs ago #11

More from the paper cited by OKIsItJustMe .... eppur_se_muova 6 hrs ago #13

"It must have been a real pleasure to work out the mathematics of MPD for the first time..." OKIsItJustMe 6 hrs ago #16