The Laser-Packing TBIRD Flies High to Deliver 100 Gigabit Per Second Data From Space

TBIRD, the TeraByte InfraRed Delivery developed at the Massachusetts Institute of Technology's Lincoln Laboratory, has hit a record data transmission rate of 100 gigabits per second via laser — meaning future satellites will be able to communicate three orders of magnitude faster than today.

"We've demonstrated a higher data rate than ever before in a smaller package than ever before," boasts program manager Jade Wang of the project, which began in 2014. "While sending data from space using lasers may sound futuristic, the same technical concept is behind the fiber-optic internet we use every day. The difference is that the laser transmissions are taking place in the open atmosphere, rather than in contained fibers."

TBIRD itself is based on three commercial off-the-shelf (COTS) parts: a high-speed optical modem, high-capacity storage, and an optical signal amplifier. After subjecting everything to the tests required to ensure they'll operate in space — including shock and vibration testing for launch, thermal vacuum testing to ensure they won't overheat in orbit, and radiation exposure testing — the team set about developing the protocol required for high-throughput yet high-reliability space-to-ground communications.

"If the signal drops out, data can be re-transmitted, but if done inefficiently — meaning you spend all your time sending repeat data instead of new data — you can lose a lot of throughput," explains system engineer Curt Schieler. "With our ARQ [Automatic Repeat Request] protocol, the receiver tells the payload which frames it received correctly, so the payload knows which ones to re-transmit."

Combined with an error-signaling system that does away with the need for a bulky gimbal, allowing TBIRD to be considerably smaller and lighter than its predecessors, the team's creation is compact yet performant — and, at 100Gbps throughput, around 1,000 times faster than what we have in orbit today. It's not just theory, either: TBIRD was launched as part of a CubeSat in May this year, beginning a testing process for live communications with a ground station on California's Table Mountain at the NASA Jet Propulsion Laboratory (JPL) Optical Communications Telescope Laboratory.

"We intended to demonstrate a low-cost technology capable of quickly downlinking a large volume of data from LEO to Earth, in support of science missions," Wang says. "In just a few weeks of operations, we have already accomplished this goal, achieving unprecedented transmission rates of up to 100 gigabits per second. Next, we plan to exercise additional features of the TBIRD system, including increasing rates to 200 gigabits per second, enabling the downlink of more than 2 terabytes of data — equivalent to 1,000 high-definition movies — in a single five-minute pass over a ground station."

More information on the project is available on the MIT website.