The Pentagon's mad-science division recently launched a mind-bending plan to harvest dead satellites for useful parts. But the orbital recycling mission won't work unless the military can see which satellites it's cannibalizing.
Now, Darpa suspects it's got a solution. Instead of relying on today's telescopes, which can only move along a single axis and require lengthy periods of time to capture anything more than a "blob" in orbit, the agency wants to design an entire array of telescopes that move at multiple angles. That way, personnel here on Earth will be better able to catch a satellite's every step in the sky above.
It's all part of a larger space initiative that's been launched over the past few months by Darpa. First, the agency expressed an interest in foraging for parts among satellites that are still sky-borne, but no longer operational. More recently, they've appealed for research into cheap, easily deployable satellites to offer quick footage for soldiers on the ground, and kicked off a program to replace ground-based satellite launchpads with subsonic airliners.
This latest program, "Galileo," builds on those previous developments. Obviously, Darpa wants more satellites in the sky -- so they want 'em cheap and easy to deploy. And it makes sense to take parts from old satellites and re-use them in new ones. But that requires a lot of careful monitoring from the ground. "You not only need to be able to detect a dead satellite in GEO," Brian Weeden, a former officer with the U.S. Air Force Space Command, tells Danger Room. "But also get a good image of it so you can see the size, shape and ... condition of its solar panels and antennas, to see if it is a good candidate for salvaging."
Enter Galileo, which would vastly improve telescopic imagery by means of fiber optics technology.
Existing telescopes that are designed to track objects in geosynchronous orbit (that's around 22,000 miles above sea level) do a fair job. But when it comes to getting a detailed image, the telescopes don't fare as well. "[Telescopes] can generally tell what something is, but not much beyond a 'blob,'" Weeden says. "Those techniques that do exist for imaging often involve having a telescope stare at an object for a relatively long period of time and then a lot of postprocessing is done to develop an image."
Darpa's solution? Use multiple telescopes, and link them together with flexible fiber optic cables -- giving each telescope an impressive range of motion.
Some of that technology already exists: In an astronomical approach known as interferometry, scientists use an interconnected array of telescopes to collect multiple phase angles (the angle between a light source like the sun, an object like a satellite, and an observer). But right now, connecting those telescopes requires rigid light pipes, which limits the range of motion of each telescope. But light pipes are necessary, because they combine all the phase angles collected by the satellites into one central hub so that an accurate image can be rendered.
To attain the ideal of sensitive stargazing, Darpa's new program would do away with those rigid light pipes entirely, and replace them with fiber optic cables (like those that transmit TV to your big-screen, for example). Because those cables are flexible, they'd allow each telescope to rotate more freely (right now, the satellites are confined to a single axis of movement) and therefore capture more angles of an orbiting satellite.
"If you can move the telescope around you can get multiple phase angles faster than waiting for the satellite to slowly drift," Weeden says.
Sure, it sounds like a big investment just to keep tabs on a bunch of sats limping towards death. But keep in mind that this same system could also be deployed to monitor foreign satellites -- which might come in handy when Chinese ones stage their next mysterious rendezvous. Not to mention the benefits of job creation: Darpa anticipates employing heaps of robotic space grunts to forage for those spare parts.
