WASHINGTON – NASA recently announced its Space Technology Program and chose two companies, Deployable Space Systems, out of Goleta, Calif., and ATK Space Systems, of Commerce, Calif., to develop advanced solar arrays for future spacecraft. NASA argued that high-power solar electric propulsion was one of the keys to extending humanity’s reach into space in terms of manned space travel, communications satellites, and unmanned exploration. NASA also said the new systems would feature dramatically reduced weight and size requirements. They are also expected to greatly improve efficiency.
NASA will allow the two companies to compete for the next 18 months, developing solar array technology in hopes of earning $5-7 million and moving on to a second phase of the selection process, which will involve testing the systems in space. The first phase of the selection process will involve testing a scalable solar array system capable of generating more than 30 kilowatts and identifying the largest risk of complications from building a 250-kilowatt unit.
Solar panels were first placed on a spacecraft in 1958, when the Vanguard 1 satellite was launched. Solar power is often used to run sensors, climate control, and telemetry, in addition to spacecraft propulsion. Solar arrays in space are organized into long sheets, with one edge attached to the main body of a satellite or spacecraft, with the sheets visually resembling a dragonfly’s wings.
In 2005, solar arrays in space were producing around 7 kilowatts per “wing,” or section, mostly because of a general lack of efficiency. The current systems on many satellites only convert about 14 percent of the sunlight they contact into usable energy. Solar technology added to the International Space Station in 2006 allowed for closer to 33 kilowatts of production, although the technology is still considered outdated. Some solar cells can now convert up to 90 percent of sunlight into energy. Looking at NASA’s request for photovoltaic cells scalable to a 250-kilowatt capacity, we can surmise that the program is looking to produce more power from a single section of photovoltaic cells than most entire satellites full of arrays produce today. Making more power from less surface area will allow for cuts in the total weight of satellites and spacecrafts. As in the past, it’s likely that NASA’s research expenditure will push planet-side solar technology to new heights as well.
The current Solar Array Wings, as NASA calls them, are 112 feet long and 39 feet wide. The wings on most space-faring devices are programmed to rotate themselves or the entire device’s structure so that they are almost always facing the sun. In the past, solar arrays have only been deemed usable near the inner solar system, where unobstructed sunlight can be constantly collected, but more efficient systems could extend the usable range of solar energy farther away from the sun. There are only two ways to get solar technology to work at a greater distance from the sun, essentially scientists have to exponentially increases either the efficiency or size of solar arrays and if these companies succeed in increasing output to anywhere near 250-kulowatt’s per wing, NASA will have met that goal. “The technology embodied in these proposals will greatly advance the boundaries of NASA's science and exploration capabilities,” NASA’s Space Technology Program Director Michael Gazarik explained. “Our investment in this technology acknowledges that this technology is a priority for NASA's future missions, as reported recently by the National Research Council. Once matured through these ground tests, NASA hopes to test next generation solar array systems in space, opening the door for exploration of a near-Earth asteroid, Mars and beyond.” The improvements also represent one step closer to science fiction, as increasing efficiency could someday lead the US or other countries to attempt to collect solar energy from space and transfer it down to Earth.