Rocket scientists at the University of Alabama in Huntsville are figuring out how the use of nuclear power would affect the components of a manned mission to Mars.
Working under a NASA grant, UAH researchers are examining — not the design of a nuclear engine but, rather — the results and costs of choosing nuclear thermal propulsion (NTP) for such a ride.
Nuclear power would provide the fuel-efficient energy needed to go the distance, but a hydrogen rocket would still be needed for the tremendous thrust needed to propel a spacecraft into orbit.
You’re talking about a nuclear reactor strapped to a rocket engine, straddled by human riders.
“We’re trying to figure out – assuming you can make the engine – can we fit it to the vehicle and make it work,” says Dale Thomas, UAH’s eminent scholar in systems engineering, who is the principal investigator for a UAH research grant with NASA’s NTP Program Office.
“The heartbeat of the program at this time is demonstrating that the reactor elements can be manufactured such that they will function in and survive the intense environment internal to the engine,” says Thomas.
Initial testing is underway at NASA’s Marshall Space Flight Center in the Nuclear Thermal Rocket Element Environmental Simulator facility.
One of the first problems that NASA asked UAH to research is the heating effect that the NTP engine’s gamma ray and neutron emissions will have on the hydrogen stored in the propellant tanks.
“Hydrogen, which must be in its liquid state to be used as NTP propellant, must be chilled to near absolute zero,” Thomas says. “And it turns out that hydrogen is a great absorber of neutrons, and a good absorber of gamma rays.”
Because it’s difficult to turn the reactor off and on due to the thermal effect on its materials, it has to idle when not in use. While idling, the reactor continues to generate heat. Perhaps hydrogen can be directed through the core to carry that heat to radiators coated with a thermoelectric compound that generate electricity, Thomas suggests.