by Joe Murray

Created on: July 24, 2008   Last Updated: August 08, 2008

A journey to Mars can be made relatively safely with acceptable hazards for the crew, but not by conventional means. After nearly a decade of research for my first novel, "Trajectories," I realized that for a "practical" manned mission to Mars, four conditions must be met.

First: The propulsion rockets must involve a nuclear reaction.

The semi-elliptical path between low and high orbits that best economizes fuel, called a Hohmann transfer, will take a chemical rocket at least 8 months to reach Mars from Earth. Once there, the crew will have to wait another 13 months for Earth's solar orbit to re-synchronize with Mars' before the crew can start their return journey, which will take another 8 months to complete.

Such an ordeal will subject the crew to nearly two and a-half years of bone demineralization, severe muscle atrophy and radiation exposure in a confined environment suffered in psychological isolation. And the longest time spent in space so far has only been 438 days on the Russian Mir.

However, if the journey can be made in about 77 days, the crew can turn around and rocket directly back to Earth without waiting for the planetary orbits' to sync-up.

And if the trip can be made in, say, 70 days, the crew will have 14 days to take pictures and collect surface samples. But this not only means a rocket acceleration to 13 kilometers per second (plus Earth's 30 kps, this totals to an escape speed of 43 kps), but this same high-energy burn (270,000 GigaJoules for a 600,000 kg spacecraft) must be done 4 times - the rockets will have to be fired again to brake into Mars' orbit, and two more times for the return journey; a third time to break Mars' orbit, and a fourth to brake into Earth's.

But a chemical rocket able to achieve such energies would have to be the size of four Empire State Buildings, laid end-to-end, and already parked in Earth orbit.

A nuclear rocket would not be so long; maybe the length of a football field.

Such an engine might consist of four stages and would burn hydrogen as a propellant in a reaction so hot that helium might be developed as a fusion by-product.

Second: The mission should be tandem.

By this I mean that, for the further safety of the crew, and until the real hazards of such journeys reveal themselves, two separate spacecraft should make the initial few journeys. At most, these space crews will be 80,000,000 kilometers (50 million miles) distant from Earthly help.

It would be a happy amalgamation of science if the U.S., Europe, Canada

• 1
• 2
• Next Page >>