[LINK] On the interest of Russia in nuclear rocketry

[rfmcdonald]

Wired's Nick Stockton notes the interest of Russia's Roscosmos in developing nuclear thermal rocketry to make quick manned interplanetary flights. Something like this may indeed be needed for crewed interplanetary flight to be viable. The central prbolem is one of funding.

Nuclear thermal is but one flavor of nuclear propulsion. Rosatom did not respond to questions about their system’s specs, but its announcement hints at some sort of thermal fission. Which is to say, the engine would generate heat by splitting atoms and use that heat to burn hydrogen or some other chemical. Burning stuff goes one direction, spaceship goes the other.

The principle isn’t too far from chemical propulsion. The fastest chemical rockets produce thrust by igniting one type of chemical (the oxidizer) to burn another (the propellant), creating thrust. Chemical or otherwise, rocket scientists rate propulsion methods based on a metric called Specific Impulse, “Which means, if I have a pound of fuel, for how many seconds will that pound of fuel create a pound of thrust,” says Robert Kennedy, a systems engineer for Tetra Tech in Oak Ridge, TN, and former congressional fellow for the US House of Representatives’s space subcommittee. For instance, one pound of the chemical mixture powering the Space Launch System—NASA’s in utero rocket for the agency’s planned mission to Mars—produces about 269 seconds of thrust in a vacuum.

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The engines the Soviets and Americans were developing during the Space Race, on the other hand, had at least double a chemical rocket’s specific impulse. Modern versions could likely do even better. Which means spaceships would be able to carry a lot more fuel, and therefore fire their thrusters for a longer portion of the trip to Mars (bonus: artificial gravity!). Even better, a thermal fission spaceship would have enough fuel to decelerate, go into Martian orbit, and even return to Earth.

Calling for a fission mission to Mars is great for inspiring space dreamers, but Russia’s planned engine could have practical, near-term applications. Satellites need to fire their thrusters every so often to stay in their ideal orbits (Also, to keep from crashing to Earth). Sokov thinks the main rationale for developing a nuclear thermal engine would be to allow for more of these orbital corrections, significantly increasing a satellite’s working lifespan. Fission power would also give probes more maneuverability. “One civilian application is to collect all the space junk,” says Sokov. “You are free to think of other, perhaps not as innocent applications.”

Russia may have the will to go nuclear, but it probably lacks the means. Rosatom has budgeted roughly 15 billion rubles on the project, which began in 2010 and is scheduled to have a launch-ready vehicle by 2025. That’s about $700 million: eyebrow-raisingly cheap for a 15-year long space project. For reference, just the rocket part of NASA’s Space Launch System is projected to cost nearly $10 billion.

And those 15 billion rubles don’t include the cost of launch, which could be why Rosatom made its 6-weeks-to-Mars announcement last week. “Going public can serve a number of purposes, including getting funding, increasing visibility, things like that from politicians, readers, and others who would like this visionary thing,” says Sokov. Rosatom plans to have a land-based test reactor by 2018.