NASA’s ST5 Microsatellites Ready for February Launch

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NASA scientists have completed the construction of three microsatellites designed to test a variety of future applications such as better collection of space weather data.

The satellites, which are the centerpiece of the agency’s Space Technology 5 (ST5) mission, weigh approximately 28 kilograms each, use a small transponder to communicate with the ground and operate by a micro-thruster about the size of a liter bottle, according to Candace Carlisle, deputy project manager for ST5.

NASA will ship the microsatellites in early December to Vandenberg Air Force Base, Calif., where they are scheduled to be launched Feb. 28 aboard a Pegasus rocket built by Orbital Sciences Corp. of Dulles, Va.

Orbital’s Pegasus rocket launches small satellites into low Earth orbit. An aircraft carries Pegasus up to approximately 12,000 meters, releases it, and the rocket free-falls for five seconds before igniting its motor.

They will be integrated onto the Pegasus using a launch rack that stacks all three satellites one on top of another and then “spins them off like Frisbees” one at a time as they are released into space, Carlisle said.

The mission is classified as a “technology validation” project, meaning it is a brief mission — in this case, 90 days — designed to show new technologies functioning in space that could be valuable for future projects. It is part of NASA’s New Millennium Program, and cost $130 million to complete, including the price of the launch vehicle , according to Carlisle.

“We’re going to demonstrate that these small spacecraft can do useful science,” Carlisle said.

NASA is trying to demonstrate the benefit of having multiple small satellites taking measurements at the same time at different locations, according to Carlisle. While only three are being demonstrated in this scenario, NASA scientists can envision scenarios where tens or even hundreds of spacecraft could be used to measure certain phenomena, Carlisle said.

One example of an application is collecting space weather data, according to Jim Slavin, project scientist for ST5. Space weather, which includes such phenomena as solar flares or coronal mass ejections , can interfere with satellite communications and GPS signals. Coronal mass ejections, sometimes called “solar hurricanes,” are large bubbles of gas threaded with magnetic field lines that get ejected from the Sun over a time period of several hours.

Satellites such as those being tested in the ST5 mission could be used to gather data on solar wind, charged particles, gamma rays, wind, lightning and other factors that influence space weather. That kind of data hopefully will lead to more accurate predictions, Slavin said.

ST5-style spacecrafts could prove beneficial for exploring the more far-reaching corners of the galaxy, such as investigating distant systems of moons, Flavin said.

Several decades into the future, Flavin said space telescopes could be maintained by swarms of small spacecraft similar in design to ST5, though such projects are theoretical at this point.

Technology being tested on the ST5 flight already is finding its way into NASA programs and proposals, Carlisle said.

For example, the propulsion tank is being used on NASA’s Dawn mission, and the mini-magnetometer is being included in several future proposals. Also being used elsewhere is the satellite’s sun sensor and its power systems, Carlisle said.