ImageWhile working on designing an X-ray navigation system for NASA's next-generation Black Hole Imager, Dr. Keith Gendreau, a physicist at the Goddard Space Flight Center, developed the world's first X-ray communication system.

NASA Tech Briefs: One of the projects you've spent considerable time on in your career at NASA is something called the Black Hole Imager. What exactly is the Black Hole Imager and what is it designed to do?

Dr. Keith Gendreau: The Black Hole Imager is one of the vision missions that's in the Beyond Einstein Program. Its objective is to actually resolve the event horizon of a super massive black hole, and it will do this by extremely high-angular-resolution x-ray imaging. When I say "extremely high," I mean better than a tenth of a microarc second. That's about a million times finer than the Hubble Space Telescope.

NTB: Tell us a little bit about the work you, specifically, did on that project. What were you personally trying to accomplish?

Dr. Gendreau: I was the study scientist on that project. That means making sure that we have a good science argument and a technology roadmap that would map to the science objectives that we want to meet. Also, as part of that, we would actually build components around the laboratory for testing things. So we've made very small-scale x-ray interferometers to try and do x-ray imaging using interferometry, which is actually the technique that would be used in the Black Hole Imager.

NTB: While you were working on that project, you came up with the concept of using x-ray sources as navigation beacons for the spacecraft that would eventually make up the Black Hole Imager. Explain that concept to us.

Dr. Gendreau: The optics for a Black Hole Imager are going to be distributed over a kilometer in the sky and spread out among 30 or 40 spacecraft. These spacecraft have to fly in formation, holding these optics at the places they need to be so that when they concentrate their light onto a detector, which is a further 20,000 kilometers behind the swarm of optics spacecraft, you would actually get the black hole image.