posted March 15, 2012
Following three years of design, fabrication, and test, Aerospace delivered two CubeSats to a national security space agency, and one CubeSat to the Space and Missile Systems Center in January.
CubeSats, which are a specific type of small satellite, measure 10 centimeters on a side and usually weigh less than 1.3 kg. Aerospace is one of the creators of small satellite technology, and has been designing, building, and operating nanosatellites (1 to 10 kg) and even smaller picosatellites (0.1 to 1 kg) since 1999.
“We designed, fabricated, tested, and operated the 250-gram mass PicoSat 1.0 spacecraft over a decade ago, and they are still the lightest active satellites ever flown,” said Siegfried Janson, a senior scientist in the Physical Sciences Laboratories.
Since then, the PicoSat group at Aerospace has built six picosatellites, as well as 10 nanosatellites during the past 13 years. The group also developed a miniature propulsion system, which was licensed last summer to a company called Austin Satellite Design. Austin Satellite Design plans to fly this system on University of Texas CubeSats in the next few years.
In general, small satellites provide a number of advantages compared with their larger counterparts — namely, they are inexpensive, they require less time to build, and they are small enough to simply “hitch a ride” on a launch vehicle.
“Small satellites can be designed, fabricated, and tested within a year, and flight opportunities, at least for CubeSats, are becoming available every few months,” Janson said.
In fact, sometimes it doesn’t even take a year. An example of how quickly Aerospace created one of these diminutive satellites occurred last year.
“Our PicoSat group, led by David Hinkley, went from concept to flight hardware delivery within six months on the PicoSatellite Solar Cell Testbed-2 (PSSCT-2) spacecraft when a ride on the last U.S. space shuttle suddenly became available,” Janson said.
This small satellite measured 5″ x 5″ x 10″ and weighed 3.6 kg. It was launched by the space shuttle Atlantis (STS-135) on July 21, 2011, and operated until its re-entry in early December.
Because they can be built so fast, small satellites can be used to test new technologies and discover and fix problems earlier.
“The design, build, test, get flight data, and redesign cycle can now be as short as six months, thus accelerating space system evolution by five to ten times compared to traditional development cycles,” Janson said. “This enables risk reduction on major flight programs by identifying and correcting issues with new component or subsystem technologies earlier in the development cycle.”
A number of the small satellites Aerospace has built have been CubeSats because there are many opportunities to launch CubeSats.
CubeSats are placed in box-like ejection tubes called Picosatellite Orbital Deployers (PODS), which are flight-qualified for different launch vehicles and can hold a variety of CubeSats.
“This is analogous to the ubiquitous overseas shipping container; shippers don’t care what’s inside as long the container is within the weight limit and no hazardous materials are present,” Janson said.
PODS have flown on a variety of launch vehicles, including the U.S. space shuttle, Minotaur-1, Minotaur-IV, Taurus-XL, Falcon-1, Japanese M-V, Russian Dnepr, Russian Kosmos-3M, Russian/German Eurockot, Indian PSLV, and the European Vega launch vehicles.
Aerospace has developed two versions of its own POD, the Aerospace Picosatellite Orbital Deployer, or A-POD, which was used on multiple shuttle flights.
The three CubeSats Aerospace delivered in January—one AeroCube 4.0 and two AeroCube 4.5s — fit in a single POD and will be launched from VAFB in August on an Atlas V launch vehicle as part of a 12-picosatellite deployment.
The AeroCube 4.5s are among the most sophisticated nanosatellites ever built, with deployable solar panels to increase orbit-average power and three-axis attitude control with 1-degree pointing capability.
But the team from Aerospace is not stopping with AeroCube 4.5. Plans are already underway to build and launch two AeroCube 5.0s.
“We plan on upgrading future AeroCubes with on-orbit propulsion, improved attitude determination accuracy, and higher communications data rates,” Janson said.