Researchers push nuclear power for Manned Mars trips

December, 1999

Environmental News Network

When the Soviet-built Sputnik, the first man-made satellite, left Earth Oct. 4, 1957, it opened the door for space exploration.

As the world marks the 40th anniversary of the first Sputnik launch and the dawn of the Space Age, scientists at the University of Florida are working on a nuclear propulsion system they say could shorten a 600-day manned trip to Mars by more than a year.

"Two years is too long for astronauts to be in space," said Samim Anghaie, professor of nuclear engineering and director of UF's Innnovative Nuclear Space Power and Propulsion Institute. "Our goal is to shorten the transit time necessary to complete a manned mission to Mars, reducing the time the crew is exposed to cosmic radiation."

When the Soviet-built Sputnik, the first man-made satellite, left earth Oct. 4, 1957, it opened the door for space exploration. Sputnik's historic, short trip into Earth orbit was a small step compared with the giant leap of a manned flight to Mars, a round-trip that could take 600 days aboard a chemical-fueled rocket.

Anghaie is developing fuels for a nuclear thermal propulsion rocket to carry a manned mission more quickly into Mars orbit.

"The key to getting astronauts to Mars and back as soon as possible lies in nuclear propulsion," said Anghaie. "Using nuclear fuel rather than chemical fuel can shorten the round-trip to Mars from more than 600 days to about 200 days," he said. A small reactor about the size of a 55-gallon barrel can provide enormous power for propulsion and carry a spacecraft at much higher speeds than can an equivalent chemical system.

"The spacecraft would leave earth aboard a standard chemically fueled rocket," said Anghaie, "but once it was away from the earth, it would switch to nuclear propulsion for the trip to Mars. Nuclear power can more than double the spacecraft's speed."

The compact, lightweight system for which Anghaie has developed a conceptual model produces heat at more than 5,000 degrees Fahrenheit. Hydrogen is heated in the nuclear reactor and then exits the rocket nozzle to provide thrust.

How soon will a manned mission to Mars be feasible?

Anghaie said that the groundwork for such a mission has been well-laid by unmanned probes of Mars. Too, an astronaut's 'giant leap for mankind' onto Martian soil will borrow some well-rehearsed procedures from the Apollo moon missions.

"The manned mission to Mars will use the same landing concept that Apollo moon missions used," said Anghaie. "The craft will go into orbit around Mars, and then a landing module will depart. When descending to Mars, the craft will be able to use 'air braking.' It will slow down using the friction created by the Martian atmosphere, which is composed of almost entirely carbon dioxide."

While nuclear-powered submarines have been around for a generation, using nuclear power for spacecraft is a promising frontier, said Anghaie, but one not without critics.

"We have ground-tested nuclear-powered rockets since the 1970s and have learned a great deal about high-temperature nuclear fuels," said Anghaie.

Anghaie dismisses critics of Cassini, an unmanned Saturn probe mission with an on-board plutonium radio-thermal generating system.

"We have significant expertise in the use of RTGs to power satellites in space. There have been many space probes, such as Sojourner and Galileo, that have used nuclear material to keep equipment warm and working under the cold Martian atmosphere," said Anghaie. "The plutonium isotopes used in these satellites do not undergo fission, the reaction that produces power in conventional nuclear power plants. Instead, they use the alpha particles these isotopes emit. These particles have a very short range, so short a piece of paper could stop them. They deposit all their energy locally as heat, which is converted to electricity."

With the success of the unmanned Mars probes and the public interest they've generated, Anghaie said he expects a mandate for a manned Mars trip will crystallize soon.

For more information, contact Randy Fillmore, UF, (352)392-0186, email: rfill@nervm.nerdc.ufl.edu.