A device called a Photonic Laser Thruster is making news since a December demonstration of the technology by its inventor, Young Bae. The founder of the Bae Institute in Tustin CA, Bae has pursued antimatter and fusion research for twenty years at places like SRI International and Brookhaven National Laboratory. His current work on photon thrust is raising some eyebrows, as noted in this news release from the Institute, which quotes the Air Force Research Laboratory’s Franklin Mead:

“I attended Dr. Bae’s presentation about his PLT demonstration and measurement of photon thrust here at AFRL. It was pretty incredible stuff and to my knowledge, I don’t think anyone has done this before. It has generated a lot of interest around here.”

In one form or another, something called a ‘photon drive’ has been in the back of inventors’ minds since the days of the German researcher Eugen Sänger, who published a designed he called a ‘photon rocket’ that would use gamma rays produced by the annihilation of electrons and positrons for thrust. The problem with that one is that you can’t control the exhaust stream, since highly energetic gamma rays penetrate any materials that would be used to contain them. And in any case, Sänger’s concept is a variation on an antimatter engine, which is not what Dr. Bae is up to.

Photons themselves, having no mass or charge, present obvious problems to anyone trying to get thrust out of them. Fortunately, they do impart momentum, which is how solar sails work. What Bae’s system does is to bounce photons using “…a photonic laser and a sophisticated photon beam amplification system.” Bouncing photons between spacecraft thousands of times is said to do the trick, producing measurable thrust that can be used in space applications.

In fact, according to the Institute’s Web site, “A small scale PLP, Photonic Laser Thruster (PLT) has recently been successfully demonstrated by Bae Institute, and the result has demonstrated the principle of PLP [Photonic Laser Propulsion] by amplifying photon thrust by 3,000 times.”

Keeping multiple spacecraft in precise formation (down to nanometer lengths) may be one outgrowth of this technology, and if so, it’s an important one. NASA’s MAXIM (Micro-Arcsecond X-ray Imaging Mission), for example, would use numerous spacecraft flying in tight formation in order to study black holes. The need for precise adjustment between independent craft has resulted in Bae’s Phase II study for NASA’s Institute for Advanced Concepts. Think space-borne interferometry, with the spacecraft kept in configuration through PLT and space tethers. The resultant formation, says the Bae Institute, will prove 100,000 times more precise than existing methods of flying spacecraft in formation.

Here’s a snippet from the Phase I study that preceded Dr. Bae’s current work for NIAC:

In addition to redefining and simplifying the existing NASA mission concepts, such as SPECS and MAXIM, PTFF [Photon Tether Formation Flight] enables other emerging revolutionary mission concepts, such as New World Imager Freeway Mission proposed by Prof. Cash, which searches for advanced civilization and in exo-planets Fourier Transform X-Ray Spectrometer proposed by Dr. Schnopper. As the present concept is more publicized, many other exciting concepts are expected to be inspired by PTFF. One of such possible NASA missions is the construction of ultralarge space telescope with diameters up to several km for observing and monitoring space and earth-bound activities.

If it will get New Worlds Imager working, I’m all for it. But will it? Here’s a link to David Livingston’s interview with Bae, in which he discusses PTFF as well as antimatter and fusion concepts. This New Scientist story on Bae’s work is also helpful. Less helpful, perhaps, is the claim on the Bae Institute’s Web site, describing photonic laser propulsion as “Our patent-pending, innovative, yet highly realistic, photon propulsion concept capable of accelerating spacecraft to near light speed without propellant.”

Perhaps, but first things first. Let’s get those space interferometry missions working, and on that score, NIAC’s Robert Cassanova reminds us in New Scientist that alternative concepts are still in play.