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First X-Ray Communication System Demonstrated

Goddard Physicist Keith Gendreau, who initially set out to create an enabling technology for NASA’s proposed next-generation Black Hole Imager, ended up developing along the way the world’s first X-ray communication system.

Gendreau recently demonstrated voice communication using a modulated X-ray source he developed under Goddard R&D and Defense Advanced Research Projects Agency (DARPA) funding to a group of NASA Headquarters decision makers. He now plans to use a mid-term Internal Research and Development award to increase the system’s data rate of about 50 kbps to 1 Mbps and integrate it with X-ray optics to demonstrate a full system-level concept. Testing at Goddard’s X-ray Interferometry Testbed, using the facility’s 600-meter vacuum beamline, is scheduled for September, Gendreau said.

The goal is to some day transmit gigabytes of data per second with minimal power, but it could take some time before that happens given the technological hurdles to overcome, Gendreau said. “With laser communications, you have to point really well. That’s the problem,” he said. “In X-rays, however, it’s a thousand times harder. That’s what will push it into the future.”

Idea Started with Black Hole Imager Gendreau began work on the technology several years ago when attempting to come up with a technological solution for NASA’s proposed Black Hole Imager, an ambitious mission aimed at directly imaging the event horizon of a super-massive black hole or the “point of no return” where nothing — neither particles nor photons — can escape. The idea was to establish a constellation of precisely aligned spacecraft that would in essence create an X-ray interferometer, he said. Making sure these spacecraft remained perfectly positioned was one of the challenges Gendreau tried to address. He conceived the idea of using X-ray sources as beacons to enable highly precise relative navigation. He then thought of an idea to modulate the X-rays — where the X-ray source is turned off and on many times per second to change intensity — to create a communication system out of the navigational beacons. To do this, he used Goddard R&D funds to develop a Modulated X-Ray Source. But if you can modulate the X-rays, then you can communicate,” he said. “I didn’t start out interested in X-ray communication, but then I thought that such a system would have widespread application.” Military Applications One potential user is the U.S. military. DARPA already has invested in the technology and Gendreau hopes to get additional DARPA support in upcoming solicitations.

Goddard Physicist Keith Gendreau set out to create an enabling technology for the proposed Black Hole Imager and ended up developing along the way the world’s first X-ray communication system, which he recently demonstrated.

NASA, too, could benefit from such a technology, Gendreau said. X-ray communication can rival its laser counterpart over long distances in space. It also permits communication with hypersonic vehicles and spacecraft during that short period when the build-up of heat prevents communication during reentry. Perhaps its most significant application, at least from a civilian space point of view, is its promise to carry large amounts of data with little power, Gendreau said.

Although Gendreau views the technology as his baby, his real motivation remains with the Black Hole Imager. “Making an X-ray imager is really the goal here.

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• NASA Official: Peter Hughes
• Curator: Lisa Kane
• Page Last Updated: January 31, 2010