DARPA wants ideas for a nuclear rocket for missions in Earth-moon space

Wolfshadw

Moderator
Apr 1, 2020
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There was already an outcry prior to the launch of the Cassini mission (if I remember correctly), but NASA has been using nuclear energy in space since the early 1960s.

-Wolf sends
 
Nov 19, 2021
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I am aware of the past experience but that was with nuclear material of far smaller size. This calls for a nuclear reactor containing 20% low enriched uranium and would be thousands of times more powerful and potentially dangerous than a mere beta emitting radioisotope thermal generator. That's my concern.
 
Oct 21, 2019
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I am aware of the past experience but that was with nuclear material of far smaller size. This calls for a nuclear reactor containing 20% low enriched uranium and would be thousands of times more powerful and potentially dangerous than a mere beta emitting radioisotope thermal generator. That's my concern.
No, the uranium fuel in a NTP rocket when launched from Earth has much lower levels of radioactivity than that of the Radio-isotope Thermal Generators (RTGs) which of course have already been launched safely on numerous occasions. New unused Uranium fuel is only weakly radioactive, it's principally an alpha emitter (https://www.epa.gov/radiation/radionuclide-basics-uranium) and can be safely held in your hands (I've done so). It's only when the reactor is first taken critical and generates power that the fuel becomes highly radioactive and a potential hazard, and that's only done on a NTP rocket once it's been safely launched from Earth on a conventional chemical rocket and is safely in Space. There's a lot of misunderstanding around, some people freak out as soon as they hear the word nuclear ;)
 
Jan 11, 2020
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Green’s hate nuclear power but just think how much worse shape we would be in had those power plants been replaced by fossil fuels.
They are dogmatic fools.
 
Jul 15, 2022
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I am aware of the past experience but that was with nuclear material of far smaller size. This calls for a nuclear reactor containing 20% low enriched uranium and would be thousands of times more powerful and potentially dangerous than a mere beta emitting radioisotope thermal generator. That's my concern.
IIRC, SNAP-10 was a fully functional nuclear reactor launched into orbit and dispersed during reentry.
 
Jul 15, 2022
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The U.S. military is ready to take the next step in developing a nuclear rocket to help monitor Earth-moon space, an area it has deemed a high strategic priority.

DARPA wants ideas for a nuclear rocket for missions in Earth-moon space : Read more
Proposed armament for an orbital gunship:
1) A five inch Naval deck gun firing the hypervelocity projectile developed by the Navy for their railgun. Other projectiles:
a) a maneuverable glide round for intercepting ICBMs or ASATs during boost phase.
b) a canister round with 10,000 cubes of tungsten, each 1/2 cm per side, for orbital intercepts.
c) a kinetic kill vehicle with terminal guidance to steer itself to collide with an agile target (like another gunship with NTP).
2) A 20 to 30 mm autocannon for orbital intercepts, for the same reason they are used on aircraft, they throw 60 rounds per second, improving hit probability on high-speed targets. Ideal weapon for a Space Shuttle door gunner.

Note that the muzzle velocity of the gun plus orbital velocity exceeds escape velocity, removing concerns about projectiles becoming space junk.
Relying on gunpowder is lighter and simpler than hauling a reactor around to power a laser. The nuclear rocket of course has a reactor, but not a power reactor. Its heat load exits the engine in the rocket exhaust. To extract electrical energy, waste heat must be dissipated, and for reactors over about 1 MW (IIRC), the dissipation panels outweigh the reactor. Perhaps there is a way to tap off some energy from the propulsion reactor/exhaust, what do people think?
Also, a laser is a line-of-sight weapon, good out to about 1200 miles, the horizon distance in LEO. Projectiles can curve around the Earth, their paths predictable by orbital mechanics. Our door gunner would need to be able to integrate the differential equations of dynamics.
Missiles could be carried, but cost much more than guns and shells. They have some advantage in midcourse and terminal guidance, but kinetic kill vehicles also have terminal guidance and these could be launched from guns.
 

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