New Kickstarter ion thruster would speed space exploration using nanosatellites

For the past few decades, space exploration has largely focused on building incredible (occasionally incredibly expensive) high-end machines. It’s not hard to see why — machines like Curiosity and its rocket-powered hover crane are amazing accomplishments.
There’s another group of people, however, working to build spacecraft that can fit within 5-6 digit budgets rather than requiring yearly outlays from NASA or another national budget. Some of these programs have taken to Kickstarter in the hopes of securing funding — including a group from the University of Michigan that wants to build the Next Small Thing in thruster technology.

Improving ion thrusters

Current ion thrusters are a handy way of moving a modestly-sized spacecraft from point A to point B provided you don’t mind waiting a while for it to get there. As the name implies, these engines emit streams of ionized particles at low thrust (meaning they don’t push very hard) but at very high specific impulse (they’re very efficient). The US, ESA, and Russia have all fielded multiple ion drive technologies over the past 20 years, but most of these designs have still been fairly bulky.
The team behind the CubeSat Ambipolar Thruster (CAT) wants to change that. They claim to have miniaturized a specific type of ion thruster to a size that would allow it to power a CubeSat satellite. CubeSats, if you aren’t familiar with the term, are tiny square satellites that measure 10cm on a side and contain exactly one liter of volume. The form factor, which debuted in 1999, allows for larger satellites in a stacked configuration — a 1U satellite is 10x10x10, while a 3U satellite is 30x10x10. The goal of the original CubeSat was to create a nanosatellite which could be deployed in orbit for a cost of $65,000 – $80,000, as opposed to the multiple millions of dollars you’d normally expect.

The CAT thruster would loop around the Earth multiple times, building up enough speed to reach escape velocity.

Potential applications of CubeSats range from practical (measuring the local magnetic field) to quirky — last year, NASA launched its “PhoneSat,”  as part of a project to demonstrate that the guts of an ordinary cell phone could serve as the avionics for a satellite in certain conditions. The CAT team wants to extend their potential uses — by putting an engine on the back. The slimmed down ion thruster wouldn’t be capable of going very fast, but the team believes it could be used to launch objects out of Earth orbit by looping around the planet repeatedly.
The CAT design is based on a specific kind of ion thruster, the Helicon Double Layer Thruster. To date, its’ been verified and tested by the ESA, but not deployed in any spacecraft. The group believes it’s found a way to scale the design down to markedly smaller craft and is looking for funding to make that a reality.

The value of small things in really big spaces

It’s fair to note that CubeSats are basically toys — minimally functional boxes that can handle a few things. A set of CubeSats of equal weight or volume to Curiosity wouldn’t result in more Mars exploration — just a lot of wasted effort. With that said, there’s real benefit to developing this kind of technology. A future probe launch could use a CAT thruster to launch secondary probes or take fine-grained measurements of a particular planetary characteristic. The CAT team at Kickstarter speak of searching for life with a CAT-mounted CubeSat, but a CAT engine on a larger spacecraft could allow for better orbital maneuverability or, used in pairs, could provide additional delta-v (trajectory-changing velocity) after launch.

A diagram of an electrostatic ion thruster (as in NASA’s NEXT, and most other ion thrusters)

At first I was skeptical of the CAT organization’s claims — I’m skeptical of Kickstarter in general — but after reviewing the literature on ion thrusters and the credentials of the group, plus looking at some of NASA’s own efforts in this area, it’s clear that there’s benefit to developing engine technologies that can boost small, low-cost payload from low Earth orbit (LEO) out to deep space. Bringing the cost of such technology downwards is an effective way to lower the cost of space exploration and fund the creation of devices that don’t risk years of work and tens of millions of dollars on a single successful launch.