Lee Steffeney, left, and Bill Hansen hold segments of the demonstrator glass-ceremic satellite developed at Aerospace for the Defense Advanced Research Projects Agency in December 2004.

Tiny Glass Satellites Represent New Concepts, Technologies

EL SEGUNDO, Calif. (1/28/05) -- Scientists in The Aerospace Corporation's Micro/Nano Technology Department are fired up about the tiny glass demonstrator satellites they’ve been developing. There are so many aspects to these satellites, which introduce new concepts and technologies and potentially vastly different ways of making satellites, that there’s a lot to get excited about.

“They are much smaller, about one-one-hundredth of the size of today’s satellites,” said senior research associate William Hansen.

Aerospace scientists and engineers have been testing the satellite’s thrusters on something similar to an air hockey table. “It’s working wonderfully and just as we’d hoped,” Hansen said.

The team is led by Dr. Henry Helvajian and includes Hansen, Adam Huang, Dr. Siegfried Janson and Lee Steffeney.

In December 2004 the scientists presented a working model of a demonstrator satellite with all of the functional properties of the real thing to the Defense Advanced Research Projects Agency, or DARPA, in Washington, D.C. The team soon expects to have another demo ready that will do leader-follower maneuvers on the air table.

Benefits of Glass

The tiny glass satellites have the potential to cut the high costs and lengthy production times associated with most present-day satellites and could spawn a new generation of missions. “They can be mass-produced inexpensively and “mass-customized, ” said senior scientist Helvajian.

Helvajian explained that glass offers many properties that other materials do not. “It’s transparent and allows for intra-satellite communication via the use of photonics. This reduces problems associated with cabling and wiring.”

The glass satellites are laser patterned in three dimensions, placed in a furnace for ceramization, and chemically “etched,” with a hydrofluoric acid solution. The end result is a patterned and etched ceramic glass, much like Corningware™, but with precision cuts with a resolution of five microns (one-tenth of the thickness of a human hair), Helvajian explained.

Additional design benefits of the glass satellites are that certain system functions can be integrated into the structure, like the fuel tank is in the demonstrator. “There is no need for an independent fuel tank. This removes excess weight and allows for additional compatibility,” said Hansen.

“Glass in the form of a glass ceramic composite is not brittle either. A cousin of this material is already used in space. We’ve flown these ceramics as part of a solid rocket microthruster array experiment on a sounding rocket and they’ve survived,” said Helvajian, adding, “This material is as tough as nickel. We can shape and mold it, change the color and strength locally. This can’t be done with aluminum or stainless steel and [this material] offers significant advantages in developing integrated small satellites.”

How They Work

The current demonstrator glass satellite contains seven patterned wafers and a circuit board with guidance navigation and control features that can take electronic commands remotely. It measures four inches in diameter by half an inch thick and weighs 330 grams (approximately 0.7 pounds) with fuel. “They are beautiful and look like they were machined on a mill. It’s not MEMS (microelectromechanical systems) technology, but some of these features could not be produced any other way,” said Helvajian.

Why glass satellites? According to Helvajian, “We needed to develop something lightweight and mass-producible that will survive launch loads. As a material class, glass ceramic is an extremely versatile material.”

The demonstrator contains a propulsion module sized for a one-kilogram (2.2 pounds) mass satellite inspector designed to co-orbit a cooperative mothership. The inspectors would be “kicked out” of the mothership once it’s launched and on orbit. “They are a pair of eyes that can circle outside the mothership and send us back information about antennaes that didn’t come out, tiles that are damaged, and repairs that may be needed, or simply assist as calibration sources. Once they serve their function, they are designed for controlled de-orbit,” Helvajian said.

A related Aerospace project is the MEMS Picosatellite Satellite Inspector (MEPSI). This team is developing similar one-kilogram mass spacecraft based on conventional satellite materials and design. “The MEPSI program will demonstrate the basic nano/picosatellite inspector concept and the glass satellite effort could provide improved performance and capabilities for the mid-term (five-to-ten years from now),” said Helvajian.

“Multiple satellites could also be sent out to cover a large area. Satellite inspectors could have a mission life of one-to-six months. If you lose a few, it’s not a problem, because they are so inexpensive to produce,” explained Helvajian.

“Aerospace Homegrown”

Janson, a senior scientist, first brought the concept of the nanosatellite (mission viable satellites that weigh one-kilogram) to light more than a decade ago. “Way back when, Siegfried started working with these ideas. No one had tried to do this, and we first had to find the right material and then develop techniques for processing. The work is truly Aerospace homegrown in every sense,” said Helvajian. “We are very proud. Two patents have been issued in relation to the work, and we have three more pending.”

The satellites are designed to be manufactured via a process called digital direct manufacturing. “The design, form-fit testing, and the patterning of the wafers is all digital, so a robot can build them to specification,” Helvajian said. This saves on the costs and time in producing the satellites. “There’s even talk that they could be produced in two weeks,” he added.

To those who might question the ability of a tiny satellite, Helvajian said, “If a satellite primary mission is supposed to be an antennae dish, it doesn’t need to be a big blocky thing. These advances could change the shape and size of tomorrow’s satellites so they look more like the primary payload rather than a bus with baggage on top.”