Australasian Science: Australia's authority on science since 1938

Circuits for Satellites

By Stephen Luntz

For a wide brown land, the prospect of finding water has always been tantalising. Now a final-year engineering student has found a way to contribute to this quest, winning a scholarship to attend the NASA Academy in the process.

The proposed Garada project will bounce L-band radar signals off the land below to study 300 km-wide strips of soil for water content. The system relies on rapid switching between broadcast and receiving mode. However, the challenge that was set to Cooney was to slow down the frequency with which pulses would need to be sent out.

“If you reduce pulse repetition frequency you can improve the images that are returned, and the demand on other parts of the system is less high,” Cooney says. “You can spend less money on equipment and get the same quality images.”

Such a challenge could have been daunting for an undergraduate student, but Cooney set about combining all the system requirements in a more efficient manner and designed the circuit on his computer. “The most rewarding thing about the project was getting the finished board back from the assembler, and holding in my hands a design I had been staring at on a computer screen for months,” Cooney says.

“If you send a polarised signal through the atmosphere, a range of factors change it,” Cooney explains. “Normally one mitigates by using all polarisations – sending on horizontal and receiving on vertical for example. You need lots of frequency to do this. However, if you can just send a signal once and run a sequence of captures you don’t need to send so many times. You can cut down by around four the number of signals required.”

Remarkably, the circuit Cooney designed worked first time, winning him the Data Processing and Electronics category of the Australian Space Prize, a joint project of NASA and the Victorian Space Science Education Centre (AS, Nov/Dec 2006, p.14).

“Thomas’ work is very impressive for an undergraduate, and his prize is richly deserved. The circuitry is fundamental to a new way of distributing the electronics across a very large satellite antenna,” said Prof Andrew Dempster, Director of the Australian Centre for Space Engineering Research (ACSER) at the University of NSW, where Cooney did his work.

The prize includes a 10-week placement at NASA’s Ames Research Centre, one of the institutions Silicon Valley was built around. Cooney’s project there was on rotorcraft. “I did a conceptual monoblade vehicle, like a maple seed, and explored how it would descend on Venus,” Cooney says. “You could make it reasonably small – something less than 1 metre in size could carry equipment of some value,” Cooney says. “It seemed to work in the model of the Venusian atmosphere. The issue is to trade off of descent time and impact velocity, as the idea is to be able to do surface measurements as well.”

Dempster described Cooney’s success as “a clear example of how space projects both attract and inspire the best engineering students, a message that often falls on deaf ears in Australia.”

“The attitude and ethos of the projects is to make interns part of the centre,” says Cooney. “With 900 interns over the summer and 3000 staff, there was almost a campus feel.”

Cooney says he only found out about the prize at the last minute, and would encourage other Honours and fourth-year students interested in space research to look into it in future years.

Cooney says “having a lot of Lego as a kid” was the prime inspiration for his career choice, although having a father who was an electronic engineer was also probably a factor. He chose to study electrical engineering as he had “a bit of interest in robotics,” but adds that “electronic engineering looked useful for lots of things. I’ve worked in a beer factory, logistics, an electrical substation company and now a biotech company, so I’m glad that expectation was correct.”

Now based at Cochlear, Cooney expects to be there for some time, but is still rotating between different parts of the firm in the course of his graduate placement and is not sure where he will specialise.

Cooney’s work for Garada may help reveal the heath of the water table and assist with the distribution of water rights in areas such as the Murray-Darling Basin. ACSER may also explore applications for other satellite programs seeking to study the Earth beneath them in cost-effective depth.