Almost everyone recognizes that if humans really want to penetrate deeper into the solar system, we need faster and more efficient propulsion systems than conventional chemical rockets. Rocket engines powered by chemical propellants are great for breaking the chains of Earth’s gravity, but they consume far too much fuel when used in space and don’t provide optimal control over a spacecraft’s thrust.
NASA also recognizes this. So in 2015, the space agency awarded three different contracts for the development of advanced propulsion systems. Of these, perhaps the most intriguing is a plasma-based rocket – which runs on argon fuel, generates a plasma, excites it and then pushes it out of a nozzle at high speed. This solution has the potential to shorten the travel time between Earth and Mars to weeks instead of months.
But to realize that potential, the Houston-based Ad Astra Rocket Company must first demonstrate that its plasma rocket, VASIMR, can fire continuously over a long period of time. NASA’s three-year, $9 million contract required the company to fire its plasma rocket at 100 kilowatts for 100 hours by 2018.
This week, Ad Astra reported that it remains on track toward that goal. The company completed a successful performance review with NASA after the second year of the contract, and it has now fired the engine for a total of 10 hours while making major changes to the large vacuum chamber to handle the thermal stress on the rocket engine.
When Ars visited Ad Astra in early 2017, he pulsed his rocket for about 30 seconds at a time. Now the company fires VASIMR for about five minutes at a time, founder Franklin Chang-Diaz told Ars. “The limitation right now is moisture escaping from all new hardware in both the rocket and the vacuum chamber,” he said. “This overwhelms the pumps, so there’s a lot of conditioning that needs to be done little by little.”
As the company continues to test the new hardware, it gradually builds up to longer and longer pulses, with inspections in between. Ad Astra remains on track to conduct the 100-hour test in late summer or early fall 2018, Chang-Diaz said.
Initially, the company envisions the plasma rocket as a means of pushing cargo between Earth and the moon — or to Mars. With solar-powered solar panels, the rocket would have relatively low thrust and therefore move payloads slowly but efficiently. But with more power, such as from a nuclear reactor in space, it could one day reach much higher speeds that would allow people to travel quickly through the solar system.