February 01, 2021
A New Take on NERVA
One of the Brickmuppet's Crack Team of Science Babes brings us this video on recent developments in the the world of rocketry.
The Scorpion is also described on pages 214-237 of the July 2019 issue of the Journal of the British Interplanetary Society. Almost everything in this ship is off the shelf, it's just tweaking existing technologies. Of course, system integration can be fraught to say the least, but this doesn't require any real breakthroughs.
In fact, this was initially studied as an alternate history study by the British Interplanetary Society of what COULD have been developed given a more robust space program from the mid-'90s on.
The ship design is pretty interesting, with a layout similar to the Eagles from Space 1999. That is is because the nuclear engines can't really be throttled, and landing in one's own radioactive dust cloud is not a spaceflight best practice.
The landing engines are at 90 degrees to the main engines and the ship is designed to carry cargo in the manner of a flying crane.
"Tell them about the engine! The engine!"
'Kayy...
The SCORPION nuclear rockets are similar to the old NERVA rockets but use integral arc-jets in the nozzles to accelerate the exhaust to insane velocities. This gives both good thrust AND a very high exhaust velocity. It's not quite a torch ship but it combines the best traits of arc-jets and ion drives with nuclear thermal rockets.
But wait.
There's more!
Once a nuclear, thermal rocket is lit off, it becomes deadly to any unshielded people within about 100 miles. There is a shadow shield that protects the crew quarters of a nuclear ship, but operating around space stations, or even in lunar orbit passing over a settlement is problematic.
This reactor design has enough thrust to allow for a shield that completely surrounds the engine, and the fuel rods can be retracted into a sort of safe when the engine is not thrusting. this allows the rocket 360 degree safety when the main engine is disconnected, allowing it to dock at space stations or land on moons near settlements without worry.
Because the control rods, once activated, will be hot (thermally as well as radioactively) a liquid cooler and radiators will be required. This has the happy side effect of using the waste heat of even the inactive main engine to power a generator or thermocouple, allowing for enough auxiliary power to support an active cooling system for the propellant and any conceivable hotel load.
Finally, the ship does have artificial gravity, but without the engineering malpractice involved with a rotating pressure seal.
This is a really interesting design particularly when one remembers that it was designed with more modest lift capabilities than we now have in prospect in the form of Musk and Bezos's new large rockets.
UPDATE:
Unsurprisingly, it turns out there is a very good overview of this design and the engine at Atomic Rocket. It notes that the performance of this "Integrated NTR Arcjet" is close to that of a Nuclear Lightbulb engine.
Posted by: The Brickmuppet at
09:27 AM
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1
So is this thing nuclear thermal or nuclear electric? The limitations on Isp in either case is the temperature you can operate at with hydrogen. Hydrogen for the low molecular mass - ve ~ sqrt(k*T/m) where m is the average mass of your molecule or atom.
(Don't have time to read the paper right now, but skimming - it looks like an arcjet.)
(Don't have time to read the paper right now, but skimming - it looks like an arcjet.)
Posted by: MadRocketSci at Wed Feb 3 10:10:19 2021 (hRoyQ)
2
Yes!
It's an NTR rocket that has its propellant accelerated by an arcjet giving it a performance in the same ball-park as the theoretical performance of a gas core nuclear rocket that somehow doesn't instantly become space Chernobyl.
So is this thing nuclear thermal or nuclear electric?
Yes!
It's an NTR rocket that has its propellant accelerated by an arcjet giving it a performance in the same ball-park as the theoretical performance of a gas core nuclear rocket that somehow doesn't instantly become space Chernobyl.
Posted by: The Brickmuppet at Wed Feb 3 10:26:41 2021 (5iiQK)
3
It belatedly occurs to me that we maybe ought not to continue referring to Nuclear Thermal Rockets as NTRs because....
Well...just because.
Well...just because.
Posted by: The Brickmuppet at Wed Feb 3 10:33:21 2021 (5iiQK)
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