The objective of the Power Beaming Challenge was to demonstrate technology for a space elevator by powering a climber up a cable. Starting at 50 meters (164 ft.) in 2005, the goals increased each year to reach a climbing height of 1 km for the 2008 contest. The first two contests were dominated by spotlights and mirrors reflecting sunlight.
“The first year we competed, 2007, was the first where they increased the height from 50 to 100 meters. That was tough to do with a searchlight,” says Kare. “It was the first time that the best way was a laser. The next year it was 1 km, and nothing but a laser would work.” LaserMotive won the $900,000 Level 1 prize in 2009 by climbing the 1-km cable at 3.8 meters/sec., but never achieved the 5 meters/sec. required to win the $1 million Level 2 prize.
“It was a reasonable path. It got us going with the right kind of technology, the lasers and receivers,” says Tom Nugent, co-founder and CEO. “It was not a detour, but after we won the first challenge the organizers told us there would be an additional round [in 2010]. We started improving the hardware in expectation of another round. Then it was canceled, which cost us six months of time and money.”
To a fledgling company like LaserMotive, the reversal came at a huge cost. But where many entrepreneurs raise cash by winning business-plan competitions, the NASA challenge gave it an opportunity to show its technology in action. “Having hardware demonstrated in the field was so much more valuable than a business plan, and a huge accelerator for us,” says Nugent. The publicity generated by the challenge was also a big benefit.
But winning the challenge did not generate the follow-up from NASA itself that the company had expected. From August 2010 to March 2011, LaserMotive did participate in a beamed-energy propulsion study funded by NASA Glenn Research Center and the U.S. Defense Advanced Research Projects Agency. It showed that a small single-stage-to-orbit (SSTO) laser thermal launch vehicle, called Laser HX, was technically feasible.
“For the first time we got a working design for an SSTO,” says Kare. The concept uses a ground array of 50-kw laser modules to beam 220 megawatts of power to a heat-exchanger panel on the launch vehicle. Hydrogen propellant is pumped through the panel, heated and expelled through a nozzle to produce an efficient propulsion system that can vary its specific impulse from low on takeoff to high in orbit.
Companies including Aerojet, ATK and Lockheed Martin looked at the power-beaming propulsion concept under NASA's Ride the Light study in September 2011. “Everybody said it would work,” says Kare, but there has been no follow-on work. “We are all set to do tests of a microchannel heat exchanger, but there is no money,” he says. Instead, LaserMotive has focused on the unmanned aircraft systems market.
“We had been envisioning UAS as a likely initial market, so as we ramped down from preparing for a second round we started responding to inquiries that were coming in from the military within a week or two of winning the competition,” says Nugent. LaserMotive demonstrated power beaming to a model helicopter in 2010 and later set a record for laser-powered flight by hovering a small quadcopter UAS for almost 12.5 hr. “We turned around pretty quickly to the market we saw,” he says.
“We began seeking follow-on development funds from the military,” says Kare. “People knew about the challenge, and it gave us a certain amount of technical credibility.” This led to work with Lockheed Martin's Skunk Works to power the company's Stalker small UAS by laser—first in the wind tunnel, for 48 hr., then later outdoors over the desert.