HOUSTON -- NASA should send a scientist with a spinal cord injury to the International Space Station (ISS) to conduct medical research, said Rick Hansen, a paraplegic who has raised millions for spinal-cord studies.

"I believe someone who has a spinal cord injury who is a scientist will got to the International Space Station," Hansen told the World Space Congress. In the weightlessness of space, "the wheelchair is irrelevant," Hansen said in an address that had some audience members in tears.

Later, Hansen told reporters he was issuing "a challenge" to NASA officials to pick a spinal-cord-injured scientist to lead a mission to the space station. He said he would discuss his proposal with managers at Johnson Space Center Wednesday.

Hansen, 45, was paralyzed in a car accident at the age of 15. He became a prominent wheelchair athlete and once rolled his way around the world to raise money for spinal cord research. Hansen is president of The Rick Hansen Institute in Vancouver, Canada.

Sending a spinal-cord-injured scientist to the station would raise awareness for research, but the main goal would be to make medical breakthroughs, Hansen said. There is a pool of highly skilled scientists who would compete for such a slot, he added.

If NASA officials reject the idea, Hansen said he would raise it with Russian officials or leaders of the fledgling Chinese human space program. "Its an international space community," he said.

Hansens proposal might be ahead of the stations capabilities, one doctor warned. The lack of a roomy crew rescue vehicle, which limits the crew size, is a stumbling block to significant scientific work on the station said Dr. Michael DeBakey, a prominent heart surgeon and advocate of NASA medical research.

Until that problem is solved, "the amount of research that can be done on space station is going to be extremely limited," he said.