Starlink is a satellite constellation being constructed by American company SpaceX to provide satellite Internet access. The constellation will consist of thousands of mass-produced small satellites, working in combination with ground transceivers. SpaceX also plans to sell some of the satellites for military, scientific, or exploratory purposes.
Concerns have been raised about the long-term danger of space junk resulting from placing thousands of satellites in orbits above 1,000 kilometers (620 mi) and a possible impact on astronomy, although SpaceX is reportedly attempting to solve the latter issue.
The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in May 2018 to be about US$10 billion. Product development began in 2015, with the first two prototype test-flight satellites launched in February 2018. A second set of test satellites and the first large deployment of a piece of the constellation occurred on 24 May 2019 UTC when the first 60 operational satellites were launched. The SpaceX satellite development facility in Redmond, Washington, houses the Starlink research, development, manufacturing, and on-orbit control operations.
As of February 2020, SpaceX targets commercial operation to begin throughout North America sometime in 2020, and much of the rest of the world sometime in 2021. However, these are only internal projections and not set dates.
Satellite hardware
The Internet communication satellites were expected to be in the smallsat-class of 100-to-500 kg (220-to-1,100 lb)-mass and were intended to be in Low Earth Orbit (LEO) at an altitude of approximately 1,100 kilometers (680 mi), according to early public releases of information in 2015. In the event, the first large deployment of 60 satellites in May 2019 was 227 kilograms (500 lb) and SpaceX decided to place the satellites at a relatively low 550 kilometers (340 mi), due to concerns about the space environment. Initial plans as of January 2015 were for the constellation to be made up of approximately 4,000 cross-linked satellites, more than twice as many operational satellites as were in orbit in January 2015.
The satellites will employ optical inter-satellite links and phased array beam-forming and digital processing technologies in the Ku and Ka bands, according to documents filed with the U.S. Federal Communications Commission (FCC). While specifics of the phased array technologies have been disclosed as part of the frequency application, SpaceX enforced confidentiality regarding details of the optical inter-satellite links. Early satellites are launched without laser links, in October 2019 SpaceX expected satellites with these links to be ready by the end of 2020.
The satellites will be mass-produced, at a much lower cost per unit of capability than existing satellites. Musk said, "We're going to try and do for satellites what we've done for rockets"."In order to revolutionize space, we have to address both satellites and rockets." "Smaller satellites are crucial to lowering the cost of space-based Internet and communications".
In February 2015, SpaceX asked the FCC to consider future innovative uses of the Ka-band spectrum before the FCC commits to 5G communications regulations that would create barriers to entry since SpaceX is a new entrant to the satellite communications market. The SpaceX non-geostationary orbit communications satellite constellation will operate in the high-frequency bands above 24 GHz, "where steerable earth station transmit antennas would have a wider geographic impact, and significantly lower satellite altitudes magnify the impact of aggregate interference from terrestrial transmissions".
Internet traffic via a geostationary satellite has a minimum theoretical round-trip latency of at least 477 ms (between user and ground gateway), but in practice, current satellites have latencies of 600 ms or more. Starlink satellites would orbit at 1⁄30 to 1⁄105 of the height of geostationary orbits, and thus offer more practical Earth-to-sat latencies of around 25 to 35 ms, comparable to existing cable and fiber networks. The system will use a peer-to-peer protocol claimed to be "simpler than IPv6", it will also incorporate end-to-end encryption natively. However, no details on this have been released as of yet.
Starlink satellites use Hall-effect thrusters with krypton gas as the reaction mass for orbit raising and station-keeping. Krypton Hall thrusters tend to exhibit significantly higher erosion of the flow channel compared to a similar electric propulsion system operated with xenon. but, at a lower propellant cost.
Competition and market effects
See also: Satellite constellation § Communications satellite constellations, and Satellite internet constellation
In addition to the OneWeb constellation, announced nearly concurrently with the SpaceX constellation, a 2015 proposal from Samsung outlined a 4,600-satellite constellation orbiting at 1,400 kilometers (900 miles) that could provide a zettabyte per month capacity worldwide, an equivalent of 200 gigabytes per month for 5 billion users of Internet data, but by 2020, no more public information had been released about the Samsung constellation. Telesat announced a smaller 117 satellite constellation in 2015 with plans to deliver initial service in 2021.[108] Amazon announced a large broadband internet satellite constellation in April 2019, planning to launch 3,236 satellites in the next decade in what the company calls "Project Kuiper", a satellite constellation that will work in concert with Amazon's previously announced large network of twelve satellite ground station facilities (the "AWS Ground Station unit") announced in November 2018.
By October 2017, the expectation for large increases in satellite network capacity from emerging lower-altitude broadband constellations caused market players to cancel some planned investments in new geosynchronous orbit broadband communications satellites.
Criticism
A large number of planned satellites has been met with criticism from the astronomical community. Astronomers claim that the number of visible satellites will outnumber visible stars and that their brightness in both optical and radio wavelengths will severely impact scientific observations. Because the Starlink satellites can autonomously change their orbits, observations cannot be scheduled to avoid them. The International Astronomical Union and National Radio Astronomy Observatory have released official statements expressing concern on the matter.
SpaceX representatives and Musk have claimed that the satellites will have minimal impact. Many professional astronomers have disputed these claims based on initial observation of the Starlink v0.9 satellites on the first launch, shortly after their deployment from the launch vehicle. In later statements on Twitter, Musk stated that SpaceX will work on reducing the albedo of the satellites and will provide on-demand orientation adjustments for astronomical experiments, if necessary.
SpaceX has mitigated concerns about the long term danger of space junk resulting from placing thousands of satellites in orbit in part by lowering the planned orbit of the satellites. Failed satellites are expected to deorbit within a few years.
