Seven years before Franklin Chang-Díaz earned his astronaut wings as a payload specialist on a 1986 satellite-deployment mission piloted by now-NASA Administrator Charles Bolden, the Costa Rican-born physicist came up with VASIMR — a plasma rocket concept he continued to refine over a 24-year NASA career during which he flew a record-tying seven space shuttle missions.

Drawing upon his doctoral work at the Massachusetts Institute of Technology on applied plasma physics and controlled fusion and postdoc work at nearby Charles Stark Draper Laboratory on inertial and magnetic confinement fusion and high-temperature plasmas, Chang-Díaz invented VASIMR in 1979 and has been working on its development ever since.

As he was preparing to retire from NASA in 2005 following a nearly 12-year stint as director of Johnson Space Center’s Advanced Space Propulsion Laboratory, Chang-Díaz founded the Ad Astra Rocket Co. in nearby Webster, Texas, to commercialize VASIMR for various in-space propulsion applications. 

Short for Variable Specific Impulse Magnetoplasma Rocket, VASIMR is an electric thruster that converts a noble gas such as argon, xenon or helium into a superheated plasma that is channeled through a magnetic nozzle to produce thrust. Ad Astra Rocket Co. ground-tested a VASIMR prototype in 2009, running the unit at 200 kilowatts — a tiny fraction of the 200,000 kilowatts VASIMR would need to make good on its promise of 40-day trips to Mars. 

The numerous technical challenges associated with such a game-changing capability prompted Mars Society President Robert Zubrin to label VASIMR a “hoax” in a SpaceNews op-ed in 2011. 

Chang-Díaz readily acknowledges that VASIMR-powered manned Mars missions would require development of a megawatt-class space nuclear reactor, a lengthy and expensive undertaking that is not exactly at the top of NASA’s to-do list. Which helps explain why Ad Astra is emphasizing in-space refueling, lunar cargo transport, orbital debris removal and on-board space station propulsion as it seeks to raise the $100 million the company needs to build a VASIMR prototype NASA has agreed to host on the international space station (ISS).

The company’s name — Ad Astra, a Latin phrase meaning “to the stars” — is surely a giveaway of the ultimate target eyed by Chang-Díaz. “All the others are just way points,” he said. “But we don’t want to get too far ahead of ourselves.”

Chang-Díaz spoke with SpaceNews correspondent Leonard David regarding VASIMR and its future, as well as the trajectory of the U.S. space program.

Given your space travel experience, how do you view the NASA of today?

My sense is that NASA and the big aerospace companies are almost frozen in time in a very beautiful chapter of American history, with the Apollo program, the space shuttle and so on. But I think today the chemistry is different. The world has changed in the last 20 or 30 years. There are many nations that have become spacefaring nations. Now, of course, the Chinese are adding themselves to that mix. So the U.S. is no longer the only key player. NASA needs to think of itself more as a player than always the captain. It may end up being the captain, but let that be decided by results. The chemistry of space is different now than it used to be. NASA has not fully recognized the difference in this chemistry — a chemistry of confrontation that used to be in the 1960s, 1970s and 1980s is now a chemistry of collaboration.

The other thing that I see right now, and it’s a fundamental paradigm shift, is that the private sector is moving into the field of space with its own skin in the game. Companies are putting their own private money into this game whether or not the government is there.

And that’s the case for Ad Astra?

We’ve been in business for nine years. We have received virtually zero funding from NASA, something that most people find extremely strange. We’ve invested about $30 million into the VASIMR. It’s all private investors. We have about 200 private investors from the U.S., Europe, Costa Rica and other places. We have a very rich investor community and these are folks looking at the business of space. Space is now a place of business, a place of work. It’s not just a place of exploration. Our project has matured to the point that now NASA is interested in this technology. 

VASIMR has been criticized, specifically by Mars Society President Robert Zubrin, who labeled the engine a “fantasy power system” and a “hoax.” What’s your response?

I think his criticism is not really against the technology. He sees it as a distraction in that by developing this technology, we’re essentially procrastinating or essentially delaying the [human] landing on Mars. He believes we ought to go to Mars now, with whatever it is that we already have — chemical propulsion systems. He and I differ in that respect. I don’t think a mission to Mars given the present technology of chemical propulsion is that feasible. I think it’s survivable. But it would be an extremely fragile mission.

And the VASIMR technology itself?

I don’t think Zubrin and I differ on the technology because he really doesn’t know the technology that much. I have told him that I didn’t appreciate him saying that we were a hoax, because we’re definitely not a hoax. We have an engine here that has been running for three years. It’s been fired 10,000 times. You can touch it. You can see it and see the data we’ve published. So it’s definitely not a hoax.

Zubrin also argues that we don’t have a nuclear reactor that can put out megawatts of power for the VASIMR. That’s true. My take on that is that we need to hurry up and develop one that can power such an engine. When you do that, you can do missions to Mars that are just under a couple of months, one-way. You can do extremely fast missions.

Can you detail the prospect of testing VASIMR on the international space station?

The station is a beautiful laboratory to do this kind of testing. We have a NASA agreement in place to fly a plasma rocket experiment as a major element of our company’s Aurora electric power and propulsion test platform on the ISS. We’re now moving to build the flight unit. Of course that takes money and we’re looking for investors all over the world.

How much money is needed?

We will need about $100 million to finish the flight article and the Aurora together. Once on the station, about three years from now, we require only about three to five kilowatts because we have a battery storage module in the Aurora platform. We store the energy and then we fire at 200 kilowatts for about 15 minutes before we charge again. 

What’s really interesting is that the Chinese are also building a space station. In fact, on my recent trip to China, they were pretty open and might be interested in a joint mission with the U.S. for testing this kind of propulsion system on their own space station. Of course, all of these space stations, be it ISS, the Chinese station, a commercial Bigelow station — they require reboost, and that’s one of our business scenarios.

So there’s a business case for VASIMR technology?

That’s the only way we’re going to get investors. We see testing on the ISS as our commercialization gateway. The engine and its performance will have been validated in space. At that point we see a number of important applications with our engine technology, such as being integrated into a freeflyer for debris removal and cleaning up the lanes in space, as a reboost module for space stations or reboosting satellites that are too high to be deorbited, or as a space tug, and also as a space catapult to deploy large objects deep into the solar system.

We have about five or six technology applications that will begin essentially right after that 2016 demonstration. That’s our plan.

How would the payload get to ISS? Aboard a NASA-funded Dragon or Cygnus resupply flight?

We have not downselected yet. We could consider either one of the options.

Leonard David has been reporting on space activities for nearly 50 years. He is the 2010 winner of the prestigious National Space Club Press Award and recently co-authored with Apollo 11’s Buzz Aldrin the book “Mission to Mars — My Vision for Space...