Particle physics art

Reflecting on the innovative antenna that led to the discovery of water on Mars – now. Powered by Northrop Grumman

Following the recent landing of NASA’s Mars Perseverance Rover, a 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 given a particularly daunting challenge: to develop a 40-meter-long antenna powerful enough to probe beneath the surface of Mars, and capable of adapting to Mars-Express, a space exploration mission proposed by the European Space Agency (ESA).

At the time, the team had no idea that their innovative antenna would eventually support the discovery of liquid water on Mars.

Pioneer of a new concept

The team had the opportunity to get creative by 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 chief technologist for MARSIS. “Our client provided the required thickness and length of the radar antenna and then asked to come up with an idea on how to install it in the spacecraft and then deploy it in space.”

The antenna had to be built for low frequency radar, so it had to be very long when fully deployed in orbit. But it had to be stowed about 1.5 meters long during transport and able to fit on the side of a spacecraft the size of a subcompact car.

Luckily, the team had a few tricks in their deployable toolbox. Since 1958, their company, Astro Aerospace, had been at the forefront of space-deployable structure technology — devices that can be radically reconfigured once in space.

For the MARSIS mission, the team designed a lightweight, deployable dipole antenna: two 20-meter poles or poles, which would collect information by sending radar pulses to the surface of Mars and receive pulses back. A shorter third boom would eliminate interference between actual signals and possible dispersion, like a really big set of rabbit ears for your TV.

The most innovative aspect of the design was a new concept devised by Marks, called the Collapsible and Flattened Tube (FFT) poles, which allowed the antennas to be stored. FFT booms could support the full length of the electrical elements of the antenna and, like the cardboard tubes inside rolls of paper towels, were long, light, thin-walled and, with delicate engineering, capable of to bend.

Taking MARSIS from concept to reality

In just a few years, the first-of-its-kind deployable antenna was developed by Astro Aerospace’s group of problem-solving enthusiasts with backgrounds ranging from bicycle mechanics to PhDs in physics.

“Technicians and engineers both brought different aspects of the equation to run the hardware,” said Michael Beers, who was MARSIS’s structural engineer. “You need a diversity of skills and experiences to take a product from concept to execution.”

The team took advantage of computer simulation tools to successfully test MARSIS components, an important step because Earth’s gravity makes it physically difficult to test fully-built deployable space hardware, according to senior business development representative Bob Chang.

“On Earth, the antenna doesn’t stick out straight like it does in space, so these mock demonstrations are key to building our confidence in mission success,” Bob said.

A cool and wild ride

In 2004, a year after arriving on Mars, the MARSIS antenna was deployed – and the MARSIS team redeployed to new projects, from solving satellite telecommunications challenges to working on products studying effects of climate change.

Still, Marks said it wasn’t difficult to follow the Mars Express, as its findings have been published in numerous scientific journals – including the thrilling discovery of a subglacial liquid saltwater lake trapped under the southern ice cap of Mars. One of the antenna’s most groundbreaking discoveries, it upended the previous belief that water only existed on Mars in solid or gaseous form. Later searches found three additional bodies of water.

“We knew MARSIS was intended for deep surface penetration, but we didn’t know what we would find with it,” Marks said. “It’s pretty cool and a wild ride that MARSIS found liquid water on Mars, which could 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 February 18. For one year on Mars – approximately 687 Earth days – the Rover will collect information to deepen our understanding of Mars.

While new discoveries on Mars often take several years – or, in the case of the MARSIS antenna, more than a decade – to make, that never discourages engineers and forward-looking scientists. After all, each team builds on the hard work of its predecessors, believing that their work today will pave the way for those to come.