Fission-powered rockets could halve the time it takes to get to Mars, but there's the whole issue of actually building one
Right now, scientists around the world are all working towards one mission: Setting foot on another world for the first time. Unfortunately, it turns out those other worlds are really far away, meaning NASA has to figure out how to manage astronauts in such isolation for such extended durations — or simply figure out how to get folks to Mars in less time.
The latter is the focus of a proposal from Dan Kotlyar, associate professor of nuclear and radiological engineering at the Georgia Institute of Technology, which suggests that the real problem isn’t the distance from Earth to Mars — it’s how fast we can get from point A to point B. Kotlyar argues that our reliance on chemical fuels is what’s holding us back, and that going nuclear could cut travel time to Mars in half:
Conventional chemical propulsion systems use a chemical reaction involving a light propellant, such as hydrogen, and an oxidizer. When mixed together, these two ignite, which results in propellant exiting the nozzle very quickly to propel the rocket.
These systems do not require any sort of ignition system, so they’re reliable. But these rockets must carry oxygen with them into space, which can weigh them down. Unlike chemical propulsion systems, nuclear thermal propulsion systems rely on nuclear fission reactions to heat the propellant that is then expelled from the nozzle to create the driving force or thrust.
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Nuclear propulsion would expel propellant from the engine’s nozzle very quickly, generating high thrust. This high thrust allows the rocket to accelerate faster.
These systems also have a high specific impulse. Specific impulse measures how efficiently the propellant is used to generate thrust. Nuclear thermal propulsion systems have roughly twice the specific impulse of chemical rockets, which means they could cut the travel time by a factor of 2.
Kotlyar’s proposal is, for now, just that — a proposal, one that may or may not bear fruit. If it does, however, it’ll take its own sweet time coming. Even models surrounding nuclear propulsion in space are in their early stages, let alone any actual scale tests or production of full-sized engines.
Nuclear power could, one day, take us to Mars in half the time of chemical fuels. Accounting for the time it’ll take to build the engines, however, it seems chemicals still come out ahead for our early trips to the red planet. With time, though, who knows which could win out?
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