Questions tagged [ntr]

NTR or Nuclear thermal rocket is a subtype of rocket propulsion wherein gas/fluid is heated inside a special-purpose nuclear reactor and then expelled at large velocity.

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Can nuclear thermal engine designs be shutdown in such a way as to be restartable, in space?

Nuclear thermal rocket designs have a working temperature of 2000k or greater. Shutting such a reactor down won't stop that heat production instantly - it'll take quite some time to cool. Do current ...
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Is there any way to get better performance from an NTR with non-H2 propellant?

Related: Is there some fundamental limitation that would prevent steam-powered rockets from reaching space? Thermal rockets, including nuclear thermal rockets, work best with minimal molecular weight ...
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Why do nuclear rockets (e.g. NERVA) have such poor Thrust-to-Weight ratios?

Nuclear fission releases far more energy per kilogram of fuel than conventional hydrocarbon sources. However, proposed nuclear rocket engines like NERVA (https://en.wikipedia.org/wiki/NERVA), while ...
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Are DUMBO, TIMBERWIND, and other high-thrust NTRs realistically going to deliver on promises of very high thrust/weight?

Nuclear thermal rockets (NTRs) are notable as the most mature technology (the second-most-mature is Project Orion) to provide both high thrust and higher specific impulse than chemical rockets. But "...
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How does a NTR with an afterburner perform at a stoichiometric mixing ratio?

The LANTR entry at Encyclopedia Astronautica describes how a sample nuclear thermal rocket performs at various mixing ratios of LH2/LOX. It does however stop before reaching the stoichiometric ratio ...
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Nuclear thermal rocket working fluid performance

After reading an announcement about NASA restarting NTR (nuclear thermal rocket) research I was wondering about how a working fluid would be chosen. For clarity, the working fluid is the gas that is ...
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How much thrust can a nuclear thermal rocket provide?

Which is the range of thrust (minimum and maximum) that a nuclear thermal rocket is estimated to produce? Knowing these values, which thrust to weight ratio would be able to produce?
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How does propellant flow work in a nuclear thermal rocket?

I assume a nuclear thermal rocket with a solid core first. The principle of operation seems simple enough: Bring your propellant close to your nuclear fuel, start a reaction and wait for some heat/...
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How are nuclear thermal reactors designed for cosmic rays in space?

I was reading about thorium reactors here. It says 'Th-232 is fissionable with fast neutrons of over 1 MeV energy'. Most cosmic rays have lots more energy than that. I haven't found a reference for ...
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What were emergency procedures for failure of launch vehicles with nuclear upper stages?

There were many studies in the 1960s, and a lesser number of later ones, for launch vehicles with nuclear-thermal upper stages. I have rarely seen mention of what emergency procedures were considered ...
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Will Roscosmos et.al attempt to revive nuclear-engine space technology violate the OST?

This article dated. 2013 writes to say After a multi-decade hiatus, both NASA and the Russian Federal Space Agency (which developed many of its own NTRs during the Cold War but never physically ...
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What are the economics of Nuclear Thermal Propulsion?

Can anyone breakdown the cost of developing and implementing an upper stage nuclear thermal engine? After development, what could the price be of each engine produced?
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Dangers of launching a nuclear thermal rocket

Nuclear thermal rockets may have great benefits for Solar system exploration. But one consideration is that the launch of a nuclear engine from Earth's surface, as the payload on a chemical rocket, ...
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Nuclear thermal rocket specific impulse calculation uses 1 amu, is that wrong?

Following the parameters in the Wikipedia nuclear thermal rocket article, it seems to paint somewhat of a shaky world view. Consider these quotes: Current (2010) 25,000 pound-thrust reference ...
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Why was the NERVA program dropped?

At the very end, NERVA (Nuclear Engine for Rocket Vehicle Application) had developed nearly flight-ready engines able to: operate for periods in excess of an hour while providing maximum thrust up to ...
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Has there been any nuclear thermal rocket test program after NERVA?

Has NASA tested any nuclear thermal rocket engine after dropping the NERVA program? Is there any current ongoing mission to use nuclear power to make a rocket fly?
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