Space has just gotten broadband.
On board was a laser poised to transmit—for the first time—an original high-definition video, Hello, World, at 100 to 200 times the speed of conventionally used radio waves. If successful, the demonstration would help overhaul space communications—a key element in increased interplanetary exploration.
"On the ground, we made an upgrade from dial-up modem to fiber optics a decade ago, and now it’s time to do that with space," said Matt Abrahamson, mission manager for the project, known as Optical Payload for Lasercomm Science (OPALS). "A lot of us have been with this project for five years. It started with an idea and today it’s real."
OPALS began in 2009 as part of a larger NASA effort to handle increasing amounts of data returning from near-Earth and deep-space missions, by relaying back home through optical rather than radio communications. OPALS transmits in the infrared (1550 nm), a faster frequency that can hold more data than radio waves. So, where spacecraft now send data via radio waves at a few hundred Kbps, OPALS transmitted at 50 Mbps. (By comparison, cable Internet companies advertise fiber optics speeds up to 15 Mbps.) "We’ll ramp up the data rate from there, to a couple hundred megabits per second," said Abrahamson. "Future systems will go up to gigabits per second. The Mars rover streaming HD video live—that’s what we want to get to."
The biggest challenge was devising a system that fit the budget—a proprietary figure rivaling that of some computers on the ISS. The result was buying commercial, off-the-shelf avionics, laser, tracking, and receiver electronics, and sealing them in a pressurized, cooled container that maintained an Earthlike environment. Fans cooled the electronics by circulating the encased air against a metal heat sink exposed to the -450˚F temperature of space.
"Typically, on a flight like this, we’d have a bigger budget and more robust avionics," said Daniel Zayas, OPALS’ thermal lead engineer. "We had to purchase components that weren’t designed for space—not hardened against radiation, don’t have a high capability in terms of temperatures, designed to work in a lab—and create a suitable environment. There was no precedent for this configuration in a JPL flight project. We were making it up as we went along, which was actually fun, because we could make up our own rules."
The group gazed back and forth between the clock and an array of computers displaying Matrix-like numbers. At 8:22 p.m., a shout, "The ISS is here!," sent a handful of folks running outside in time to catch the tiny white dot smoothly traversing the sky. Then, a white dot with a circle beamed onto one of the monitors. "We’re in!"
As the ISS traveled across the sky, the ground telescope at the nearby Table Mountain Observatory transmitted a laser beacon to the OPALS flight system, which locked on it, before beaming the video data via laser to the observatory ground receiver, which then transmitted it to JPL.
The downlink took 3.5 seconds (compared to the 10 to 15 min. it would have taken by radio wave). But processing the signal took another nail-biting 20 minutes. When Hello World burst onscreen, the room erupted in applause.
The next two months will be spent testing system nuance. Although faster frequencies can carry more data, they scatter more easily. So where radio waves pass through clouds, lasers can’t. The OPALS team will experiment with the level of cloud cover lasers can penetrate, minimum ISS elevation to successfully transmit, and downlinks to foreign ground stations in Japan, Spain, and Germany.
NASA, meanwhile has a mission in the works to demonstrate—in about four years—an optical relay communications between satellites, then to Earth, paving the way for optical transmissions from other planets. "Then you’re suddenly sending HD video back from Mars instead of simple picture snapshots," says Abrahamson.
Check out the slide show above for a behind-the-scenes look at the OPALS maiden demonstration.