OTTAWA - The Canadian Space Agency says it wants to hire former astronaut Robert Thirsk to help it figure out how to contribute medical expertise to a human mission to Mars.

Thirsk is a medical doctor who holds the Canadian record for time spent in space, thanks to an extended mission on the International Space Station in 2009.

Those are two of the qualifications the space agency considers essential for the $95,000 contract it is making public today, saying Thirsk is the only person on Earth who fits the bill.

The job involves spending the next two years determining what Canadian scientists and health experts can do to help astronauts beyond low Earth orbit, and selling the public on the benefits of investing in space-health science.

Long space missions degrade astronauts' muscles and bones, expose them to radiation and can even damage their senses.

Thirsk led the agency's expert panel that recommended work on minimizing these dangers should be how Canada helps the human race explore space.