Is an app the next spacecraft innovation?
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, 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's 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.
The PhoneSats are similar to the Spheres free-flyer experiment already conducted in the International Space Station's Destiny lab, except the PhoneSats were deposited into orbit on the inaugural. Antares launch. They will last only a few weeks in space because their orbit was 240 X 260 km (150 X 160 mi.). But in small packet bursts, they have communicated through a worldwide Ham Radio network and transmitted Earth images using smartphone technology, says Project Manager Jim Cockrell. Two PhoneSat 1s, which cost just $3,500 each, relied on Android HTC Nexus One smartphones and one $8,000 PhoneSat 2 used the more advanced Samsung Nexus S model.
The PhoneSat 1 used the phone's accelerometer and magnetometer but left its lithium-ion batteries at home because they are not suitable for the thermal shifts of working in space. Instead, the phones were snuggled diagonally into the cubesat surrounded by nickel-cadmium batteries that will barely last the length of the mission.
Although it is only a beta test model, PhoneSat 2 has greater capabilities. The Nexus uses gyroscopes so users can flip screens vertically or horizontally. Combined with a set of magna torque wheels little bigger than a man's thumb, they gave PhoneSat 2 three-axis stability, which the simpler PhoneSat 1 lacks. The Ames team simplified making mounts for the wheels with 3-D printing.
Solar cells for PhoneSat 2 came from edges discarded inSpectrolab's manufacturing process. Ames connected 20 of them on each side of the 10-cm cubesat and on the flip side built copper wire magna torque coils directly onto their PC board to save weight and space.
The point, says Korsmeyer, is to drive tailored original equipment manufacturing out of satellite-making as much as possible by adapting existing hardware. In the future, this will mean that programming the spacecraft is the biggest hurdle. “You have transformed a hardware problem into a software problem,” he says.
Because cubesats operate in low Earth orbits (nominally 425-450 km/265-2,800 mi.), they are protected by the planet's magnetic field and do not face major radiation hardening issues. “We buy rad-hard commercial parts rather than space parts,” Korsmeyer says, saving millions. He compares having to operate with occasional interference from radiation to having to reboot a PC. “Is that really a problem?” he asks.
Manufacturing for organizations that must tolerate problems or be priced out of existence is part of the smallsat culture, just as managing missions with part-time teams is. But there are payoffs to working in a Class D culture, NASA's minimum qualification standard. Bruce Yost, NASA's small technology mission director, says a “six-pack” of 3U nanosats can be built with only a third of their configuration reserved for spacecraft operations, leaving two-thirds for payload. The normal ratio is just the opposite.
Development work for very small satellites is flowing from companies such as San Francisco's Pumpkin Inc., which has an online catalog for a nanosat starter kit, although founder Andrew Kalman says International Traffic in Arms Regulations prevent fill-the-shopping cart ordering.
Started in 2004, Pumpkin is on its fifth generation of electronics. But its staff of fewer than 10 relies on specialty suppliers, such as San Francisco Bay Area machine shops that hold tolerances to 0.004 in. It used to spend 2 hr. per cell making solar panels but has cut that to just 12 min. by adapting Spectrolab cells. “Our focus has always been on how to crank out [satellites] quickly,” Kalman says. He can deliver in as little as 90 days.
Despite the existence of Pumpkin and others like it, customers still need to know what they are doing. They must source their own control software, antennas (EDNS uses hardware-store retractable tape measures) and source cells.
Pumpkin is geared to producing large numbers of the same design, so government agencies such as Ames, JPL and the National Reconnaissance Office (NRO), and prime contractors of the likes of Boeing andare its natural customer base. A contract for 12 3U cubesats from the NRO in 2007 provided Pumpkin's big push. Called Colony 1, the order is intended to seed innovation by providing institutional design teams with basic hardware. Users, such as the University of Southern California, take it from there. The NRO's Colony 1 Aeneas mission is an experiment for the to track cargo containers over open oceans by interrogating a 1-watt Wi-Fi-like transceiver on the container.
Ames also is using an approach of combining modular units in a Common Bus to simplify satellite manufacturing on a bigger scale. The first application, the $263 million Lunar Atmosphere and Dust Environment Explorer (Ladee), is set for launch on a Minotaur V in late August or early September. Other proposals are not yet funded but illustrate the design's flexibility: an asteroid mission and a lunar robotic lander for the Google Lunar X-Prize competition.
While not in the cubesat you-build-it mode, the Common Bus draws on the same philosophy to reduce costs, says Project Manager Butler Hine. Its stackable modules are made lighter and stronger by being comprised of carbon composite formed into a single monocoque octagonal blank with titanium frame inserts that have no ribs. Stress points are reinforced with added plies, and common bolt patterns on top and bottom allow for easy stacking.
Ladee's top two modules carry the instruments—a laser communications experiment, neutral mass spectrometer, ultraviolet/visible spectrometer and lunar dust experiment—and satellite avionics and communications equipment, while the bottom units contain the propulsion system. The body has fixed solar panels, giving it a single safe mode, and its reaction wheels and reaction thrusters are off-the-shelf commercial satellite hardware.
Ames leads NASA's small satellite programs largely because its director, Pete Worden, is an evangelist for their cause. Besides the promise of simplified design and reduced mission costs, his broader vision is that they will become disruptive technologies. The obvious analogy is to the smartphone and Internet. Their ubiquitous presence has created a web of interconnected electronics that beg users to create applications, regardless of whether they understand the hardware behind them. But for such an idea to work in space, satellites need to be cheap enough that a failure would not stop the innovation clock for a decade.
Ames will launch 22 satellites this year, most as cubesats ejected from the space station. Others, weighing in at 20 kg. (44 lb.), are engineering efforts relying on off-the-shelf avionics and costing less than $1 million. “For a few million bucks, you can do really cool stuff in space,” Worden says.
But the real revolution will come from what is done on the ground, although how it will be done is not yet clear. “The secret sauce of Silicon Valley is ferment,” Worden says. “What I really want to do is have one kid in her garage who says, 'I have an idea and I'm going to write an app.'”