WASHINGTON (AFP) – A journey from Earth to Mars could in the future take just 39 days -- cutting current travel time nearly six times -- according to a rocket scientist who has the ear of the US space agency.

Franklin Chang-Diaz, a former astronaut and a physicist at the Massachusetts Institute of Technology (MIT), says reaching the Red Planet could be dramatically quicker using his high-tech VASIMR rocket, now on track for lift-off after decades of development.

His rocket would use electricity to transform a fuel -- likely hydrogen, helium or deuterium -- into plasma gas that is heated to 51.8 million degrees Fahrenheit (11 million degrees Celsius). The plasma gas is then channeled into tailpipes using magnetic fields to propel the spacecraft.

The next major step, according to Chang-Diaz, will be orbital deployment at the end of 2013 of a vessel using the 200-kilowatt prototype VASIMR engine, the VX-200.
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I suspect that this is a hydrogen rocket. The goal is obviously to
go as fast as possible and hydrogen is the fastest traveling of all
combustion gases.