SpaceX's laser system for Starlink is delivering more than 42 petabytes of data to customers per day, an engineer revealed today. That is 42 million gigabytes.
SpaceX engineer Travis Brashears said at the SPI Photonics West event held in San Francisco:
We are transmitting terabits per second [of data] every day through 9,000 lasers. In fact, we serve all our Starlink users through lasers over a two-hour period.
Although Starlink uses radio waves to transmit high-speed internet to customers, SpaceX has also equipped the company's satellites with a "laser link" system to help reduce latency and improve the system's global coverage. The lasers, which can maintain a connection of 100 Gbps per link, are especially crucial for helping satellites obtain data when there is no nearby SpaceX ground station, such as over the ocean or Antarctica. Instead, the satellite can transmit data to and from another Starlink satellite in Earth orbit, forming a mesh network in space.
Brashears' Tuesday talk revealed that the laser system is quite robust, even when the equipment is flying aboard thousands of Starlink satellites that constantly orbit Earth. Despite the technical challenges, the company has achieved a laser "link uptime" of over 99%.
The satellites are constantly forming laser links, resulting in approximately 266,141 "laser acquisitions" per day, according to Brashears' presentation. But in some cases, links can also be maintained for weeks and reach transmission speeds of up to 200 Gbps.
Brashears also said that the Starlink laser system was able to connect two satellites more than 5,400 kilometers (3,355 miles) apart. The link was so long that it "crossed the atmosphere, reaching up to 30 kilometers above the Earth's surface," he said, before the connection was cut.
"Another interesting piece of data is that we maintained a link up to 122 kilometers while we were deorbiting a satellite," he said. "And we were able to transmit video."
During his presentation, Brashears also showed a slide illustrating how the laser system can deliver data to a Starlink antenna in Antarctica via approximately seven different routes. "We can switch those routes dynamically in milliseconds. So as long as we have some path to the ground station, you will have 99.99% uptime. That's why it's important to put as many nodes up there as possible," he added.
Most of the Starlink satellites currently in orbit use a "Gen 3" laser link design. But recently, the company upgraded the technology with a new "Gen 4" model. SpaceX can manufacture around 200 units per week, but to reduce costs, the company uses standard commercial components, including sensors and actuators. SpaceX also had to ensure that all components are "disintegratable" and leave no trace when a Starlink satellite is retired and burns up in Earth's atmosphere.
Looking ahead, SpaceX plans to expand its laser system so that it can be adapted and installed on third-party satellites. The company has also explored the possibility of directing lasers from satellites directly to terminals on Earth's surface to deliver data. But Brashears said a "deeper study" is needed to enable the technology.