Inflatable antennae could give CubeSats greater reach

Design inflates with a powder that turns into gas.

The future of satellite technology is getting small — about the size of a shoebox, to be exact. These so-called “CubeSats,” and other small satellites, are making space exploration cheaper and more accessible: The minuscule probes can be launched into orbit at a fraction of the weight and cost of traditional satellites.

But with such small packages come big limitations — namely, a satellite’s communication range. Large, far-ranging radio dishes are impossible to store in a CubeSat’s tight quarters. Instead, the satellites are equipped with smaller, less powerful antennae, restricting them to orbits below those of most geosynchronous satellites.

Now researchers at MIT have come up with a design that may significantly increase the communication range of small satellites, enabling them to travel much farther in the solar system: The team has built and tested an inflatable antenna that can fold into a compact space and inflate when in orbit.

The antenna significantly amplifies a radio signal, allowing a CubeSat to transmit data back to Earth at a higher rate. The distance that can be covered by a satellite outfitted with an inflatable antenna is seven times farther than that of existing CubeSat communications.

“With this antenna you could transmit from the moon, and even farther than that,” says Alessandra Babuscia, who led the research as a postdoc at MIT. “This antenna is one of the cheapest and most economical solutions to the problem of communications.”

The team, led by Babuscia, is part of Professor Sara Seager’s research group and also includes graduate students Benjamin Corbin, Mary Knapp, and Mark Van de Loo from MIT, and Rebecca Jensen-Clem from the California Institute of Technology. The researchers, from MIT’s departments of Aeronautics and Astronautics and of Earth, Atmospheric and Planetary Sciences, have detailed their results in the journal Acta Astronautica.

‘Magic’ powder

An inflatable antenna is not a new idea. In fact, previous experiments in space have successfully tested such designs, though mostly for large satellites: To inflate these bulkier antennae, engineers install a system of pressure valves to fill them with air once in space — heavy, cumbersome equipment that would not fit within a CubeSat’s limited real estate.

Babuscia raises another concern: As small satellites are often launched as secondary payloads aboard rockets containing other scientific missions, a satellite loaded with pressure valves may backfire, with explosive consequences, jeopardizing everything on board. This is all the more reason, she says, to find a new inflation mechanism.

The team landed on a lighter, safer solution, based on sublimating powder, a chemical compound that transforms from a solid powder to a gas when exposed to low pressure.

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“It’s almost like magic,” Babuscia explains. “Once you are in space, the difference in pressure triggers a chemical reaction that makes the powder sublimate from the solid state to the gas state, and that inflates the antenna.”

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