The 10-year mission cost was estimated by KISS participants at $2.6 billion in current year dollars, a figure Ad Astra believes it can lower by replacing the KISS study’s SEP strategy that relies on 40-kw Hall thrusters and Xenon as fuel. A range of Vasimr options carry price tags for the mission ranging from $326 million to $614 million by using lighter and less expensive argon or krypton as the fuel and 100- to 400-kw versions of the solar-powered Ad Astra plasma engine.
Characterizations of the VX-200 with krypton as a fuel for greater thrust began in the company’s vacuum chamber last year.
Mission estimates using a Vasimr option range from 1.8 to 4.6 years, according to Ad Astra.
“We are not trying to put anyone down,” insists Chang-Diaz. “We are happy to compete on a level playing field. We are trying to point out we have a high-power engine with enough muscle to carry out these missions.”
A second Ad Astra study envisions the Vasimr tug as an orbiting space cleaner, addressing concerns raised by NASA’s orbital debris program office, as well as the United Nations and others, that space junk levels have reached a critical point. Collisions between existing debris will inevitably spawn more junk unless some of the most menacing rocket bodies and fragments can be deorbited.
The company’s assessment proposes the use of tugs capable of deorbiting 19 large known threats, primarily spent Russian Zenit rocket upper stages. The study envisions use of the 200-kw, argon-fueled version of the Vasimr to achieve multiple plane changes.
The tug would be launched with a tray holding 20 solid rocket motors (SRMs) and a detachable chemical rocket pod (CRP) to control the tug’s close-proximity operations. Under the scenario, the cleaner would rendezvous with its 8-metric-ton Zenit targets at 800 km altitude, where it would release the more maneuverable CRP to capture and return the Zenit hardware to the tug. Once a spent upper stage is secured, the CRP would install one of the SRMs in the Zenit rocket nozzle. The tug would then descend to 400 km, where it would release the SRM-propelled Zenit for a destructive descent into the Pacific.
The low-orbiting tug would also form the nucleus of higher-altitude versions suitable for removal or refueling of communications satellites, another Ad Astra commercial focus.
A congressional emphasis on fiscal “sustainability” as an underpinning for future NASA missions has not been lost on Ad Astra, especially policy discussions over a habitat in lunar orbit, possibly at a lunar Lagrange point (L-1), which at some juncture might serve as the staging base for human expeditions to Mars.