By 
March 12th, 2014
Power beaming from space to Earth is attracting technologists.
Credit: John Mankins
The idea of power-beaming from space to Earth has long been studied. Lots of issues brought forward within lots of reports over lots of years.
New work by the U.S. Naval Laboratory (NRL) has shed new light on how to build spacecraft to first capture solar power in space and then transmit that power down to an energy-hungry Earth.
Paul Jaffe, a spacecraft engineer at NRL, has built and tested a module to capture and transmit solar power.
Jaffe has built two different prototypes of a “sandwich” module. In both designs, one side receives solar energy with a photovoltaic panel, electronics in the middle convert that direct current to a radiofrequency, and the other side has an antenna to beam power away.
Hardware that could bring about power-beaming spacecraft has been tested at the U.S. Naval Research Laboratory. Paul Jaffe holds a module he designed for space solar power in front of the customized vacuum chamber used for testing purposes.
Credit: U.S. Naval Research Laboratory/Jamie Hartman
“Launching mass into space is very expensive,” says Jaffe, so finding a way to keep the components light is an essential part of his design. He can cradle one module in his forearms.
The sandwich module is four times more efficient than anything done previously, according to an NRL press statement.
Jaffe’s work also involves a novel approach to solving the thermal problem, using the “step” module. That step module design, now in the patent process, opens up the sandwich to look more like a zig-zag. This allows heat to radiate more efficiently, so the module can receive greater concentrations of sunlight without overheating.
Two different prototypes of a sandwich module have been fabricated. In both designs, one side receives solar energy with a photovoltaic panel, electronics in the middle convert that direct current to a radiofrequency, and the other side has an antenna to beam power away.
Additionally, Jaffe has tested his module design using a customized vacuum chamber to simulate the space environment.
Large array
“The most sobering thing about all of this is scale,” Jaffe adds. He imagines a one kilometer array of modules…not to mention the auxiliary sun reflectors. To date, the International Space Station is the only spacecraft that has come close. It stretches a little longer than an American football field.
The array Jaffe envisions would span nine football fields.
In scoping out a future power-beaming satellite, Jaffe said the modules would have to be launched separately, and then assembled in space by robots.
That research is already being advanced by NRL’s Space Robotics Group.
Ripe for research
Admittedly, Jaffe notes that there are many areas ripe for research, such as the system that would reflect and concentrate sunlight onto the modules.
One proposal is to make the module even lighter, by using thinner solar panels, a flatter and lighter antenna, and using what’s called a monolithic microwave integrated circuit to put loads of functionality into a little chip.
Another prospect is a demonstration mission to assemble elements as an array in space to investigate other challenges, Jaffe concludes.
Posted in Space News
