Shoe box-size satellites one of the next big things
CubeSats are compact and cheap compared to large satellites but would be more useful if they could propel themselves into the right orbit or trajectory.
Mon, Nov 28, 2011 at 7:00 PM
One of the next big things in space innovation is a modest cube, about the size of a coffee mug or a shoe box, now being developed to circle Earth and monitor space weather, observe the atmosphere, and test the feasibility of using a sun-powered sail to tow space junk.
Over the past decade, these diminutive cube satellites, or CubeSats,have grown in importance. Some think they are poised to have a potentially profound impact on the big-budget space industry, where missions can routinely cost hundreds of millions, similar to the effect the advent of personal computers had on computing.
"Computers used to be machines that occupy whole rooms, and now you take a look at your iPad — that probably has more power than all the computers combined in the '60s," said Paulo Lozano, associate professor of aeronautics and astronautics at the Massachusetts Institute of Technology.
CubeSats can vary widely in cost, depending on their intended use, but they can cost less than $50,000 and easily piggyback on existing rockets.
"That means high schools can fly stuff into orbit, private companies can do their own missions, and there might be a host of applications that we haven't even been thinking about," Lozano said. "I think the impact can be large: low cost, high performance."
Lozano, funded by the Air Force Office of Scientific Research, is developing a propulsion system light and compact enough to fit efficiently on a CubeSat.
A Chelmsford company, Scientific Solutions Inc., is working with partners including California Polytechnic State University, the University of Wisconsin Madison, and NASA's Goddard Space Flight Center to develop a CubeSat called EXOCUBE that will measure the density of particles in the upper layer of Earth's atmosphere.
"CubeSats were seen to be an easy way to do the process of training young engineers on a smaller budget...that was the whole basis behind the CubeSat concept,'' said Dean Alhorn, an aerospace engineer at NASA's Marshall Space Flight Center in Alabama.
Alhorn leads a mission called NanoSail-D, launched a year ago. It deployed a large solar sail that is pushed along by the photons from the sun. "Now, engineers at NASA say we could fly missions on a smaller budget. Aerospace companies are looking at this.''
Scientific Solutions is a private engineering firm that has developed technologies for use in remotely sensing the composition and properties of the atmosphere. The EXOCUBE satellite it and its partners are developing is designed to measure the layer of the Earth's atmosphere where the ultraviolet light and X-ray radiation emitted from the sun create a charged layer called the ionosphere. That layer is in flux, as its size and density change in response to activity on the sun.
Understanding the composition and changes in that layer can help scientists better understand and predict space weather, which affects communications satellites and spacecraft performance.
The data from EXOCUBE may also help scientists improve their understanding of fluctuations in drag, which causes satellites to slow down and eventually burn up in the atmosphere.
The low-budget satellite, funded by a $900,000, three-year grant from the National Science Foundation, will fly into that layer of the atmosphere in late 2013. Generally rockets can carry multiple CubeSats like peas in a pod, which John Noto, president of Scientific Solutions compared to a Pez dispenser.
"The door flaps open and the spring shoots them out,'' Noto said. "Very low-tech, very reliable.''
Lozano, on the other hand, is building miniature propulsion systems — "nano-thrusters'' — that could make CubeSats even more useful.
CubeSats are compact and cheap compared to large satellite missions, but they would be more useful if they could propel themselves into the right orbit or correct their trajectory if a problem arose. Propulsion systems, however, tend to be big.
So Lozano has been developing a method of propulsion that uses a molten salt as fuel, and he expects to begin testing the technology on CubeSats sometime next year.
The NanoSail-D mission is testing whether a sail that is moved by photons from the sun — literally packets of light bouncing off a sail — can be used as a kind of space junk tow truck, taking satellites out of orbit when their useful life is over.
"Whenever you launch a CubeSat, you should be able to get rid of it after some time — they are cheap, and you don't want to contribute to space junk,'' Lozano said.
Copyright 2011 The Boston Globe
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