Reuters News
Thursday October 2 11:44 AM EDT

Nuclear Rockets

Researchers see nuke power as fast-track to Mars

By Kristi Coale

SAN FRANCISCO (Wired) - Mars exploration has created a new space race --how to get humans to the arid planet via journeys that take less than two years. Researchers at the University of Florida believe the answer lies in nuclear power.

Nuclear engineering professor Samim Anghaie and graduate student TravisKnight are developing a fuel for use in a nuclear thermal propulsion rocket that would carry a manned mission more quickly into Mars' orbit.

The fuel, a mixture of uranium, zirconium, and niobium in solid carbideform, serves as the core of a reactor that can produce heat -- from the fission of the uranium -- that exceeds 5,000 degrees Fareheit. Hydrogen circulates through the reactor and passes by the heat source and then through the rocket's nozzle to provide the thrust.

This core is lightweight and more efficient than traditionalchemical-based rockets, said Knight.

Because the nuclear reactor can heat to very high temperatures and is lighter, it can generate more thrust and propel a rocket to its destination faster than a chemical-based rocket.

The Florida researchers estimate that the use of the nuclear core cuts more than a year off a round trip to Mars. Chemical rockets take more than 600 days to complete a round trip; nuclear-powered rockets can complete the trip in roughly 200 days.

But the use of nuclear power in space flight is very controversial. The Oct. 13 launch of NASA's Cassini unmanned mission to Saturn is under the scrutiny of a group of scientists, along with anti-nuclear activists who point to the probe's use of 72 pounds of weapons-grade plutonium to power the instruments on board the craft.

Knight discounts the danger of using a nuclear reactor in a propulsion system -- even on a manned craft -- by comparing this with the amount of radiation already in space.

"When you spend two years getting to Mars and back, you're getting a potentially lethal dose of radiation from the Sun,"Knight explained.

In any event, the nuclear-powered rocket would be powered out of Earth's atmosphere by chemical rockets. The nuclear thrusters would take over only after the craft had achieved low-earth orbit, Knight said.

The use of nuclear propulsion is not new. Knight noted that the work at the University of Florida's Innovative Nuclear Space Power and Propulsion Institute carries on from projects developed by both Russia and NASA.

Knight argued that the nuclear reactor is proven technology -- and is the only viable alternative to chemically driven rockets at present, he said.

"To use exotic technologies, breakthrough physics, is to use a technology that is not proven," he explained. "Like fusion, if you haven't demonstrated that it can work in a lab, you can't use it on a rocket."


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