Enlarge /. Starlink logo imposed on a stylized image of the earth.
SpaceX has begun launching Starlink satellites with laser links that provide broadband coverage in polar regions. As SpaceX CEO Elon Musk wrote on Twitter on Sunday, these satellites have "laser links between the satellites, so no ground stations are needed over the poles".
Enlarge /. Starlink satellites before launch. The black circles in the middle are laser connections. The laser links are contained in 10 Starlink satellites that have just been launched into polar orbits. The launch came two weeks after SpaceX received Federal Communications Commission approval to launch the 10 satellites in polar orbits at an altitude of 560 km.
"All Sats launched next year will have laser links," Musk wrote in another tweet yesterday, indicating that laser systems will become standard on Starlink satellites in 2022. Currently, SpaceX only contains laser links on polar satellites. "Only our polar saddles have lasers this year and are v0.9," wrote Musk.
Alaskan residents will benefit from the polar satellites, SpaceX told the FCC in a motion to change the orbit of some of its satellites in April 2020. The plan is to "ensure that all satellites in the SpaceX system have the same low latency." Services to all Americans, including those in places like Alaska, served by satellites in polar orbits, "SpaceX said at the time. The satellites can serve both home users and US government users" in otherwise inaccessible polar regions, "said SpaceX SpaceX.
Starlink satellites communicate with ground stations, around 20 of which are currently in use in the United States. A SpaceNews article today described how the laser links reduce the need for ground stations and offer other benefits:
Inter-satellite links allow satellites to carry communications from one satellite to another, either in the same orbital plane or in an adjacent plane. With such connections, operators can minimize the number of ground stations by eliminating the need for a ground station to be on the same satellite footprint as user terminals and extend coverage to remote areas where ground stations are not available. You can also reduce latency by reducing the number of hops between satellites and ground stations.
The 10 satellites were originally approved by the FCC for altitudes ranging from 1,100 to 1,300 km. FCC approval, which allows SpaceX to cut the height in half, helps reduce latency.
With polar orbits, also known as sun-synchronous orbits, satellites move "from north to south rather than west to east past the earth and roughly over the earth's poles," as the European Space Agency explains.
"Space lasers have exciting potential"
In December, SpaceX President Gwynne Shotwell said in an interview with Eric Berger, Ars Senior Space Editor, that the demonstration of laser communication in space is one of the company's major achievements in 2020.
SpaceX had announced a few months earlier that it was testing space lasers for data transmission between satellites. Starlink engineers provided more details in a Reddit AMA in November. Here is an excerpt from our reporting back then:
"The speed of light is faster in vacuum than in fiber, so space lasers have exciting potential for low-latency connections," replied the Starlink team on Reddit when asked about space laser testing. "They also allow us to serve users where the satellites cannot see a terrestrial gateway antenna – for example over the ocean and in regions that are poorly connected by fiber."
Space lasers won't play a huge role in Starlink in the near future, however. "We had an exciting flight test earlier this year with prototypes of space lasers on two Starlink satellites that could carry gigabytes of data," wrote the engineering team. "But cutting the cost of space lasers and getting a lot of them produced quickly is a really tough problem that the team is still working on."
SpaceX is seeking FCC OK for more polar satellites
In November 2020, SpaceX asked the FCC to accelerate approval "to facilitate the deployment of 348 Starlink satellites in sun-synchronous polar orbits at lower altitude," the FCC said in its decision to approve 10 satellites. The FCC only approved these 10 as it assessed interference concerns from other satellite companies.
"We note that the partial grant of ten satellites will facilitate further development and testing of SpaceX's broadband service in high-latitude geographic areas in the near future pending subsequent action to both support the filing arguments for the grant the entire change as well as for the complete change to clarify subset of satellites with polar orbit ", it says in the FCC regulation.
The Amazon project Kuiper, Viasat, Kepler Communications and Pacific Dataport called on the FCC to refuse even the partial granting of 10 satellites because of the possibility of increased interference with other non-geostationary satellite systems. However, the FCC regulation states that SpaceX has committed itself to "operating these satellites on a non-harmful interference basis with respect to other licensed frequency users until the Commission decides on their full change". A battle is brewing between SpaceX and Amazon. Musk accuses Amazon of trying to "hamper Starlink today for an Amazon satellite system that is at best several years out of service".