NASA installs space laser on the ISS, uses it to transmit high-speed data back to Earth

NASA has successfully completed the first test of the International Space Station’s new OPALS laser communications system. OPALS links the ISS to an observatory here on Earth at very high speeds (around 50 megabits per second), allowing for the real-time transmission of high-resolution video among other things. This is orders of magnitude faster than existing radio-based links, and is a significant step forward for future space exploration. If we ever want a real-time video feed from the surface of Mars — or if you ever want to have an intergalactic Skype call with your loved ones after humanity colonizes the Milky Way — then lasers, and other advanced communications technologies, will be required.

OPALS, which stands for Optical Payload for Lasercomm Science, was shipped to the ISS by SpaceX resupply mission CRS-3 back in April. It was hooked up to the exterior of the ISS on May 7, and the first test was presumably carried out in the last couple of weeks. The first test transmission was a high-definition “Hello, World!” video lasting 30 seconds. If you watch the video below, which I recommend, the test clip is included at the end.
OPALS is essentially a self-contained laser turret, with a two-axis gimbal that’s used for very accurate targeting. As ISS comes over the horizon, Table Mountain Observatory turns on an optical beacon that OPALS locks onto. Because the ISS orbits at such a low altitude (~230 miles) it’s only in contact with the observatory for approximately 100 seconds. The most complex part of OPALS is keeping the laser on-target for the full duration. “It’s like aiming a laser pointer continuously for two minutes at a dot the diameter of a human hair from 30 feet away while you’re walking,” explained Bogdan Oaida, an OPALS engineer at NASA’s JPL.

OPALS mission architecture diagram

During that 100-second window, OPALS modulates a 2.5-watt infrared (1550nm) laser with digital data — in this case, a repeating loop of a 30-second “Hello, World!” video. 2.5 watts is very weak, so you probably don’t have to worry about GoldenEye-like misuse. During the first test, the laser link was maintained for 148 seconds, transferring a total of around 1 gigabyte of data — a transfer rate of around 6MB/sec, or a link speed of around 50 Mbps. NASA says it would’ve taken more than 10 minutes to transfer the same amount of data via traditional S-band and Ku-band radio links. [Read: High-frequency stock traders turn to laser networks, to make yet more money.]

The OPALS instrument. From what I can tell, the laser is created in the big silver barrel. The white cowling on the right is protecting the gimbal/targeting system, where the laser is emitted.

As you can probably tell, NASA is rather excited at the prospect of using lasers instead of radio links. OPALS follows on from the success of LADEE last year, which beamed data back from the Moon at 600Mbps. Both OPALS and LADEE are important steps towards future probes and rovers that will travel deep into the cosmos and use lasers to beam high-resolution scientific data back to Earth. So you have some idea, the Mars Reconnaissance Orbiter — which relays data from Curiosity — has one of the fastest deep-space radio links, and it maxes out at just 6Mbps. If it was capable of 50Mbps or 600Mbps we’d be able to learn a lot more about the red planet. Likewise, if humanity ever colonizes some other planets, we’re going to need something a lot better than radio waves if we want to build a high-bandwidth galnet (galaxy network).

Posted in: Future Technology