Following the recent landing of NASA's Mars Perseverance Rover, one group of engineers reflected on how their innovative work with deployables led to the discovery of water on Mars.
In 2000, a small team of engineers and technicians at Astro Aerospace in Carpinteria, California (now owned by Northrop Grumman) were presented with a particularly vexing challenge: to develop a 40-meter long antenna powerful enough to survey beneath the surface of Mars, and able to fit on the Mars Express, a space exploration mission proposed by the European Space Agency (ESA).
At the time, the team had little idea that their innovative antenna would eventually support the discovery of liquid water on Mars.
Pioneering a New Concept
The team had the opportunity to be creative in coming up with a design for the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) antenna.
"It was a very 'soft' program," said Geoff Marks, who was lead technologist for MARSIS. "Our customer provided with the required thickness and length of the radar antenna, then asked to come up with an idea for how to fit it in the spacecraft, then deploy it in space."
The antenna had to be built for a low frequency radar, so it had to be very long once fully deployed in orbit. But it needed to stow to about 1.5 meters in length while in transit and be able to fit on the side of a spacecraft the size of a subcompact car.
Fortunately, the team had some tricks in their deployables toolbox. Since 1958, their company, Astro Aerospace, had been pioneering the technology of space-deployable structures — devices that can be dramatically reconfigured once in space.
For the MARSIS mission, the team designed a lightweight deployable dipole antenna: two 20-meter booms or poles, which would collect information by sending radar pulses to Mars' surface and receive pulses in return. A third, shorter boom would eliminate interference between real signals and possible scatter, like a really large set of rabbit ears for your television set.
The most innovative aspect of the design was a new concept imagined by Marks, called foldable-flattenable-tube (FFT) booms, which enabled the antennas to stow. FFT booms could support the full length of the antenna's electrical elements and, like the cardboard tubing inside paper towel rolls, were long, light, thin-walled and — with some tricky engineering — able to fold.
Taking MARSIS from Concept to Reality
In just a few short years, the first-of-its-kind deployable antenna was developed by Astro Aerospace's group of passionate problem solvers with backgrounds spanning from bicycle mechanics to doctorates in physics.
"The technicians and the engineers both brought different sides of the equation to execute the hardware," said Michael Beers, who was the structural engineer for MARSIS. "You need a diversity of skills and backgrounds to bring a product from concept to execution."
The team took advantage of computer simulation tools to successfully test components of MARSIS, an important step since Earth's gravity makes it physically difficult to test fully constructed deployable space hardware, according to Bob Chang, senior principal representative in business development.
"On Earth, the antenna doesn't pop straight out like it does in space, so these mock demonstrations are key to building our confidence in the success of the mission," said Bob.
A Cool and Wild Ride
In 2004, a year after arriving at Mars, the MARSIS antenna was deployed — and the MARSIS team had redeployed to new projects, from addressing challenges in satellite-based telecommunications to working on products studying the effects of climate change.
Still, Marks said it wasn't difficult to keep up with the Mars Express, as its findings were published in numerous scientific journals — including the exciting discovery of a subglacial lake of liquid saltwater trapped under Mars' southern ice cap. One of the antenna's most groundbreaking findings, this upended the previous belief that water only existed on Mars in solid or gas form. Later research found three additional bodies of water.
"We knew MARSIS was for deep surface penetration, but didn't know what we'd find with it," Marks said. "It's pretty cool and a wild ride that MARSIS found liquid water on Mars, which may pave the way for human exploration or even lead to the discovery of life on the red planet."
Today, NASA's quest to explore the mysteries of Mars continues with the Perseverance Rover, which landed on Mars on Feb. 18. For one Mars year — about 687 Earth days — the Rover will collect information to further our understanding of Mars.
While new discoveries on Mars are often several years — or, in the case of the MARSIS antenna, over a decade — in the making, that never deters forward-looking engineers and scientists. After all, each team builds on the hard work of their predecessors, confident that their work today will pave the way for those who follow.
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