Thursday, February 16, 2023

Aerogel NERVA (for robots)

I've scented some skepticism from Nyrath and others on rogget-twitter about whether NTR/NTP will ever happen. One serious problem is, of course, the environmental problem: getting these dangerous metals into LEO space is dangerous for LEO, and by extension to us. But: the nuclear fission fragment rocket engine doesn't have so much metal. Also leaves more mass for the mission.

This foamy uranium can burn for 15 years, with appreciable propulsion. Apparently this gives a small-ish cargo the fissile material it needs in a similarly lightweight, er, propeller. That's enough to get out to that 550 AU lens-range on about which Centauri Dreams keeps banging.

The scheme needs a superconducting magnet too but, you know, after those first dozen AUs, liquid-nitrogen temperatures are pretty-much a gimme. Just radiate out the heat from the core (bro). So: needs that first push, to 12 AU. This blog has already suggested hitting up zodiacal systems like 55 Cancri, to take advantage of planetary boosts. Venus and Jupiter, at least; since we're already planning for the long term. Out in the scattered-disk transKuiper some shielding from Sun-orbiting dust would be needed, as well.

Mind, if we're just taking this jalopy to Haumea or to Eris - maybe to decelerate halfway? - dust is less a worry. And these are ecliptic-enough.

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