By Clare Dodd and Matthew Stibbe

‘John Carter got there by standing in an open field, spreading his hands and wishing,’ said Carl Sagan. If only it were so simple, but thanks to cosmic radiation, orbital complications and between 54 and 401 million kilometers, it’s just not that easy for us humans to get to .

VASIMR-powered ship arrives at Mars

Vasimr-powered spaceship arriving at Mars. Source: Wikipedia

That said, the VASIMR rocket, developed by the Ad Astra Rocket Company might just bring human exploration of the red planet within reach. Because when it comes down to it, it’s all about the need for speed.

If we travelled to Mars now, using current chemical rocket technologies, it would take around eight to nine months. During that time, the astronauts would have to deal with muscle and bone wastage and face bombardment by cosmic radiation and solar flares.

Any astronaut would then have to wait, and survive on Mars for two years before they could come back to Earth. ‘You’re contemplating a very long camping trip on the surface of a planet that has an atmosphere you cannot breathe and very little water,’ says Dr. Chang Díaz, CEO of Ad Astra and former NASA astronaut.

That’s because a Martian solar year lasts for two of our Earth years. So while we might start out pretty close to the red planet, after 12 months Mars would be on the opposite side of the sun to us, making a journey back impossible for another 12 months. Dr. Chang Díaz likened it to Earth being on the inside track of a race; we inevitably get ahead.

It’s these obstacles that have ultimately caused the cancellation or abandonment of so many previous manned-missions to Mars. Such missions would simply cost too much money, and put astronauts at too much risk for them to be viable.

Now, if we had the technology to get to Mars in, say, three months, we would have enough time to get there and back before Earth ran too far ahead in its orbital race, making for a much more plausible mission. And that’s where VASIMR comes in.

VASIMR stands for the Variable Specific Impulse Magnetoplasma Rocket, and uses an electric plasma engine to get you moving a lot faster than traditional nuclear thermal and chemical rockets have the ability to do.

Chemical rockets work by burning a vast amount of fuel, which is expelled all in one go, but at a relatively low velocity, meaning a short sharp burst of speed. In contrast, the VASIMR rocket uses a little bit of propellant, which is expelled at very high velocities over a longer period of time; and this allows for steady and continuous acceleration.

VX-200 plasma engine at full power, employing both stages with full magnetic field. Source: Wikipedia


In the simplest terms possible, relatively cold (40,000 degrees) plasma is generated in the first of two plasma chambers within the rocket. This plasma gets heated in the second chamber to very high temperatures (more than 2 million degrees) by radio waves emitted from a radio antenna. The plasma in both chambers is too hot for any material to hold it, so all along, it is confined and guided along in a magnetic duct, which ultimately ejects all that highly-energised plasma out of the rocket in a single, concentrated direction. And it’s that directed, superheated plasma that provides the continuous acceleration, which ultimately makes VASIMR so fast.

They key ingredient in that process, however, is the power to heat the plasma in the first place. Currently, for shorter, Earth-orbital journeys, Ad Astra is planning to use solar panels to produce the electricity, but they simply wouldn’t be powerful enough for a human journey to Mars. The only alternative is nuclear electric power.

‘The engine will be ready for commercial operation using solar power,’ says Dr. Chang Díaz, ‘but for fast human transportation, who is going to develop a nuclear reactor that is space worthy is still unknown, though there are several nations besides the USA capable of doing it.’

The investment and skill needed to develop the infrastructure that would support a nuclear powered VASIMR mission to Mars is huge. It goes well beyond the manpower, intelligence and budget of any single nation, no matter the size of that country’s national pride. Instead, ‘the appropriate chemistry is one of collaboration, not confrontation like in the 1960s’ says Dr. Chang Díaz.