A new phase array radar installation in Midland, Texas

Space mapping

June 2, 2018 by Daniel McGlynn
This article appeared in Berkeley Engineer magazine, Spring 2018

As soon as Sputnik launched in 1957, the challenges facing a young spacefaring civilization started to show. Not everything that was shot into orbit came back down. At first it was a rocket body or two. By now, decades of missions and more than 6,000 satellite deployments later, there are hundreds of thousands of space debris fragments circling the Earth on orbital currents.

The ever-growing debris field is raising concerns about the viability of future space missions. Since the debris is moving at such high speeds, flying fragments contain grenade-like energy.

Space debris could even become a self-perpetuating problem: A major collision could destroy a satellite, spawning more debris, and thus more collisions, until the resulting debris cloud wipes out an entire satellite constellation, or a manned space station, or anything else in low Earth orbit. And it’s not just astronauts or satellite operators that are at risk. Earth-dwellers are becoming increasingly reliant upon space-based communications for everything from space-based Wi-Fi to precision warfare targeting.

In 2009, the corpse of a Russian Cosmos satellite collided with a still active Iridium communications satellite. Both were destroyed, resulting in a plume of new fragments — including, according to the Congressional Research Service, 2,100 pieces that are larger than 10 centimeters.

That 10-centimeter size is significant because debris that large — about the diameter of a softball — can be tracked using existing technology. Anything smaller, which potentially includes hundreds of thousands of fragments, is basically invisible to today’s tracking infrastructure, which is controlled by the Department of Defense.

Dan CeperleyLeoLabs co-founder Dan Ceperley (Photo by Golnaz Shahmirzadi)That’s where LeoLabs, a new Menlo Park-based company, comes in.

“In low Earth orbit, things can be moving at 17,000 miles an hour, so you need a ground-based service to monitor where everything is and then predict ahead,” says LeoLabs co-founder Dan Ceperley (M.S.’05, Ph.D.’08 EECS). “The cool thing, from a technology standpoint, is that you are predicting ahead about 100 revolutions, so you have to have a lot of really good data to make those predictions and then constantly refine them.”  

Instead of the stereotypical big dish radar, the LeoLabs version is a fixed trough with no moving parts. It looks somewhat like a metal-clad half pipe. Called a phase array, the radar is designed to listen for radio waves using 100 specially tuned antennas.

The radar technology is based on an earlier design that fellow LeoLabs co-founders Michael Nicolls and John Buonocore built for the National Science Foundation in Alaska. The initial radar was designed to study the ionosphere (part of the upper atmosphere where significant solar radiation interactions take place).

And then came the bycatch, and the idea for LeoLabs. “When they turned it on, they were getting all of this ionosphere data — it was the first radar of its kind — but they were also getting satellite data,” Ceperley says.

With a few measurements and some computation, the LeoLabs team can map paths and figure out if dangerous chunks of space debris are on a collision course with satellites or other spacecraft. Satellite operators can then purchase access to the data, giving them the ability to make adjustments to flight paths based on the hazards identified in the calculations from LeoLabs. 

In addition to full coverage of low Earth orbit, this year LeoLabs is working toward increasing the resolution of their radar in hopes of capturing finer-grained space debris. “We are building toward a next generation of radar that will track things down to two centimeters in size,” Ceperley says. “So suddenly the number of objects we are tracking goes from 13,000 to 250,000.”  

Topics: EECS