May 06, 2013
Credit: Pumpkin Inc.
Inexpensive satellites little bigger than a Rubik's Cube have been the provenance of university and small research projects for more than a decade. Increasingly, innovations from the smartphone world are showing how these classroom projects can play outsized roles in space science.
The April 21 launch of three PhoneSats, built here at NASA Ames Research Center, is giving early promise to what can happen when common commercial products are tapped to drive down the design, development and integration costs of making spacecraft. The innovations include cannabilizing consumer products, scrounging for leftovers and using parts from online satellite catalogs.
David Korsmeyer, head of Ames's engineering directorate, says technology and manufacturing processes for very small satellites is maturing to the point where they can become disruptive technologies for Earth observation, communications and deep-space exploration.
Interest in small satellite missions extends far beyond Ames. Innovation Foundry Manager Anthony Freeman at NASA's Jet Propulsion Laboratory says the most successful smallsat design, the 10 X 10 X 10-cm (roughly 4 X 4 X 4-in.) cubesat—the standard “1U” size—pioneered at the turn of the century, have come a long way. “For a long time, we've been in an elongated Sputnik era with peepers and squeakers, where just getting into Earth orbit and getting a signal was counted a success. We're now at the Explorer 1 level,” says Freeman, referring to the 1958 U.S. mission a year after Sputnik that detected the Van Allen radiation belt. “After that, things really took off.”
Freeman emphasizes the dollars-and-cents rationale for using very small spacecraft for exploration. “If the discussion is at the $500 million [mission cost] level, that means a lot of asteroids we won't fly by,” he says. “But if it is $2 million, then we can.”
The Edison Demonstration of Smallsat Networks (EDSN), a cluster of eight 1.5U cubesats (10 X 10 X 15 cm) is set for launch from Kauai, Hawaii, in October. They will have overlapping orbits spread over 50-60 mi. and know each other's position with high precision so their measurements can be integrated with time and position stamps. “For [scientists], there are lots of measurements that benefit from being taken just minutes apart,” says the chief technologist in Ames's mission design division, Elwood Agasid. EDSN will measure ocean temperatures and wave heights. “How fast can a storm grow?” he asks. Knowing the answer may prove useful in tsunami warnings, particularly in detecting killer waves from remote regions of the Pacific Ocean.
Three other EDSN-class technology missions are planned in the next three years. They will use cubesats no larger than 3U (10 X 10 X 30 cm) to verify: laser communications, low-cost radar and optical sensors to help smallsats maneuver near each other; higher-bandwidth radios that communicate with reflector antennas on the back of their solar arrays; and cubesat rendezvous and mechanical docking exercises.