A White House study group plans to recommend U.S. development of nuclear-propelled rockets that would send manned expeditions to Mars and deeper reaches of the solar system, an industry magazine says.

The plan envisioned by the so-called "Synthesis Group" would use one of two approaches, according to the March 18 edition of Aviation Week and Space Technology magazine.Under one version, nuclear-heated hydrogen would spew out of the rocket nozzle, propelling the craft through space.

The other possibility envisions heating argon or hydrogen until it turns to plasma and the vehicle would move through space through the force of electrostatic repulsion.

The Synthesis Group has declined to comment on what its report will say.

The group, chaired by retired Air Force Gen. Thomas P. Stafford, an Apollo astronaut, was established by NASA on White House orders to gather innovative ideas for lunar and Mars exploration. It is to report to Vice President Dan Quayle, the National Space Council and NASA about May 1.

Until now, the only use of nuclear energy by the United States in space has been in devices employing heat from radioactive pellets to provide electrical power for space probes on yearslong journeys, such as the Voyagers that photographed the outer planets.

Aviation Week said NASA's Lewis Research Center in Cleveland will begin a nuclear propulsion program next week, with the goal of producing a system within 15 years.

The contemplated use of nuclear power is bound to run into difficulties, not all of them technical. Public concerns about an accident could cause politicians to be wary of such a program. So are worries about adequate shielding for a crew in close proximity to nuclear fission.