Large spacecraft can have large antennas, but for CubeSats, which are about the size of a shoebox, there is no way to include a large parabolic dish. Most CubeSats use simple dipole antennas, restricting how far beyond the Earth's surface they can function.
Researchers at MIT have come up with an inflatable antenna design that could significantly increase the communication range of small satellites, allowing them to operate at the same altitude as geosynchronous satellite or even travel out into the solar system. Alessandra Babuscia, who led the research as a postdoc at MIT, said, “With this antenna you could transmit from the moon, and even farther than that. This antenna is one of the cheapest and most economical solutions to the problem of communications.”
Inflatable antennas for satellites aren't a new idea, but because CubeSats are packed together as secondary payloads, using conventional pressure valves could have explosive consequences. To avoid the problem, the MIT team used a sublimating powder, a chemical compound that transforms from a solid powder to a gas when exposed to low pressure.
Babuscia explained, “It’s almost like magic. 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.”
Comparing conical and cylindrical designs using Mylar and a few grams of benzoic acid to inflate the antenna, the researchers found the cylindrical antenna performed slightly better.
As the sublimating powder will create only as much gas as needed to fully inflate the antenna, any powder remaining can be used to compensate for leaks or punctures.
Kar-Ming Cheung, an engineer specializing in space communications operations at NASA’s Jet Propulsion Laboratory (JPL), commented on the MIT group’s work: “A directional antenna has been out of the question for CubeSats. An inflatable antenna would enable orders of magnitude improvement in data return. This idea is very promising.”
Testing continues at MIT.
“In the end, what’s going to make the success of CubeSat communications will be a lot of different ideas, and the ability of engineers to find the right solution for each mission,” said Babuscia. “So inflatable antennae could be [used] for a spacecraft going by itself to an asteroid. For another problem, you’d need another solution. But all this research builds a set of options to allow these spacecraft, made directly by universities, to fly in deep space.”
Comments and RF related news items are welcome. Email me at dlung@transmitter.com.
