The biggest barrier to manned exploration of Mars is the time it would take to get there – with current technology (chemical rockets) it would take about eight months. However, a new propulsion technology that uses jets of superheated plasma to propel a craft using “steady, efficient thrust” could cut that time to merely 40 days. Road trip!
A mission trajectory study estimated that a VASIMR-powered spacecraft could reach the red planet within 40 days if it had a 200 megawatt power source. That’s 1,000 times more power than what the current VASIMR prototype will use, although Ad Astra says that VASIMR can scale up to higher power sources.
The real problem rests with current limitations in space power sources. Glover estimates that the Mars mission scenario would need a power source that can produce one kilowatt (kW) of power per kilogram (kg) of mass, or else the spacecraft could never reach the speeds required for a quick trip.
Existing power sources fall woefully short of that ideal. Solar panels have a mass to power ratio of 20 kg/kW. The Pentagon’s DARPA science lab hopes to develop solar panels that can achieve 7 kg/KW, and stretched lens arrays might reach 3 kg/KW, Glover said. That’s good enough for VASIMR to transport cargo around low-Earth orbit and to the moon, but not to fly humans to Mars.
Unfortunately, while we may actually have the propulsion technology to send humans to Mars in a relatively timely manner, we don’t have the power source. Solar panels won’t do the trick, and the proposed power source, a nuclear reactor, is only a concept at this point. Even so, Ad Astra, the company that created VASMIR, has approached commercial spaceflight providers to explore potential launch options.