"NASA's Associate Administrator for Space Operations William Gerstenmaier and Ad Astra's President and Chief Executive Officer Franklin Chang Diaz signed the agreement on Dec. 8. The agreement is structured in a series of "gates," designed to allow the parties to assess milestones on an incremental basis while proceeding to flight. Upon the achievement of these milestones, NASA and Ad Astra envision that VASIMR will be launched to the station and be tested, for the first time, in the vacuum of space."
"The NASA Authorization Act of 2005, Section 507 (P.L. 109-155) designates the US portion of the ISS a National Laboratory. While smaller projects have already been initiated for installation at interior locations of the ISS, the Ad Astra project will serve as a "pathfinder" by demonstrating a new class of larger, more complex externally-installed science and technology payloads, encouraging others to pursue similar projects and facilitating their efforts with a model for implementation."
NASA Strategic Management Council Meeting 9 July 2008
"Griffin stated his desire to see a Space Act Agreement signed to fly a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) experiment, stating that the engine needs a test in space. ... Action: Space Operations Mission Directorate is to report back to the Strategic Management Council on the status of the Space Act Agreement to conduct a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) experiment on the International Space Station."