Nanosatellites offer a low-risk, low-cost platform for validating aerospace innovations.
NASA's next big thing is very small
We often think of NASA in grandiose terms -- tackling the biggest problems with the biggest thinking, applying the grandest ideas that mankind can conceive. But now, NASA is thinking small in a big way, applying a DIY ethos to spaceflight, and using commercially available tools and technologies to get the job done.
Instead of gigantic systems costing millions of dollars, and thousands of man hours to produce and launch, the next greatest idea is to focus on the small things -- using off-the-shelf products and small-scale design to take an approach to space systems research that is quicker, cheaper, and more efficient. Aboard the International Space Station, the SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites) are already doing just that.
At NASA Ames Research Center in Mountain View, Calif., home of the SmallSats Technology Program, NASA is exploring SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites), which are already in use aboard the International Space Station.
The 8-inch diameter, free-flying satellites have been aboard the ISS since 2006, and were originally developed by the Massachusetts Institute of Technology Space Systems Laboratory through the Defense Advanced Research Projects Agency and NASA Small Business Innovation Research funding.
At NASA Ames, Mark Micire works with the SPHERES, using them in an environment which replicates the conditions in space as closely as possible.
The SPHERES are equipped with a commercially available Google Nexus S -- NASA purchased them from the same big-box electronics store you and I might buy a phone from -- and software to transform them into these incredible droids.
After exploring the requirements for the SmallSats project, NASA came to the realization that low-cost, commercially available products met all the requirements for their robots. Equipped with cameras, accelerometers, Wi-Fi, and high-performance processors, the Google Nexus S fully completed all of the initial nine test objectives and met all success criteria.
The smartphones are cheap compared with satellites -- costing just hundreds of dollars, not the millions needed for a typical satellite -- require no manufacturing, and are constantly upgraded and always available immediately.
The battery-powered, 8-inch diameter satellites fly within the ISS and in the Small Satellite research facility at NASA Ames using carbon dioxide to fuel 12 thrusters.
With the SPHERES, NASA hopes to build a long-term, upgradable testbed for the validation of high-risk control and autonomy technologies for use in formation flight and autonomous docking. During space operations, these types of movement and rendezvous technologies are critical to successful operations.
These things are a bit sci-fi looking -- and that's no surprise. One of the original points of inspiration for the SPHERES -- you guessed it: Star Wars. The lightsaber training droid that Obi-Wan Kenobi deploys to test young Skywalker looks almost identical. The inspiration was not, thankfully, the Interrogation Droid, but it isn't far from that, either.
A space shuttle is the wallpaper on the Google Nexus S which is part of the SPHERES. The Nexus S' displays have been covered with a clear tape to prevent glass fragments from inundating the delicate environment on the International Space Station should an accident result in a shattered screen.
Developing and applying formation flight and docking control algorithms to real systems carries a high degree of risk, and careful assessment is needed to ensure any emerging technologies are safe to use on projects that have years of work and millions, or even billions, of dollars invested.
The complexity of these algorithms being developed for formation flight is unprecedented, NASA says, and the SPHERES testbed provides a useful intermediate step where algorithms can be verified and the algorithm development process can be validated.
These miniaturized satellites, called SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites), are autonomous robots which maneuver around inside the ISS. An infrared sensoring system is used to locate the position of each robot.
When navigating and positioning with the infrared system, compressed carbon dioxide is used to propel the droids. The four black circles seen here are a few of the ultrasonic sensors used for positioning.
NASA defines "Small Spacecraft" as those with a mass of less than 180 kilograms, but some are much smaller. Minisatellites are 100 kilograms or larger, Microsatellites are around 10-100 kilograms, Nanosatellites are just 1-10 kilograms, Picosatellites are 0.01-1 kilograms, and Femtosatellites are incredibly small, weighing just 0.001-0.01 kilograms.
NASA is developing other types of miniaturized satellites, too, including these PhoneSats. These tiny satellites make use of the commercially available HTC Nexus One smartphone and Google's Android operating system. A standard off-the-shelf smartphone from your typical big-box store has everything needed for satellite systems including fast processors, a versatile OS, multiple miniature sensors, high-resolution cameras, GPS receivers, and several radios.
"PhoneSat demonstrates a philosophy of taking a creative idea, then building and testing that inspiration in a very rapid way...as opposed to long planning processes typical of larger spacecraft programs," said Andrew Petro, NASA program executive for Small Spacecraft Technology within the Space Technology Program at NASA Headquarters in Washington.
Each "nanosatellite" is a 4-inch cube and weighs just three pounds. Some researchers at NASA believe small satellites like these may one day replace traditional large and expensive satellites currently in use. By using off-the-shelf consumer smartphones to build spacecraft, NASA hopes to speed the development process and cut the cost of production, incorporating the Silicon Valley approach of "release early, release often."
These cheaper and simpler satellites might one day be used like building blocks in space, capable of assembling and reassembling themselves into different configurations depending on the goal or task of a mission.
Currently, NASA engineers have kept the total cost of the components to build each of the three prototype satellites in the PhoneSat project to $3,500 by using only commercial, off-the-shelf hardware and keeping the design and mission objectives to a minimum.
The PhoneSats are presently housed in an aluminum framing which costs just a few thousand dollars, instead of the millions of dollars -- or more -- of a traditional satellite. But NASA wants to bring the development process even closer to home -- by hopefully integrating 3D printing into the SmallSat program.
In a project called SpaceShop being developed right now at NASA Ames, modern manufacturing tools of the digital age, including laser cutters and 3D printers, are being housed in the second floor of a machine shop in an initiative that NASA hopes will speed the development and iteration process for small satellites.
Rather than outsourcing expensive custom technologies to meet mission requirements, engineers might one day be able to rapidly upgrade an entire satellite's capabilities right in-house.
Expected to launch in 2013, NASA's upcoming Edison Demonstration of Small Satellite Networks mission -- part of the Small Spacecraft Technology Program -- will demonstrate the possibility of conducting heliophysics measurements using small spacecraft.