Starlink (satellite constellation)

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Starlink[1] is a satellite constellation development project underway by SpaceX, to develop a low-cost, high-performance satellite bus and requisite customer ground transceivers to implement a new space-based Internet communication system.[2][3] By 2017, SpaceX had submitted regulatory filings to launch a total of nearly 12,000 satellites to orbit by the mid-2020s.[4]

SpaceX has plans to also sell satellites that use the same satellite bus and these satellites may be used for scientific or exploratory purposes.[5]

Development began in 2015, and prototype test-flight satellites were successfully launched on February 22, 2018.[6][7] Initial operation of the constellation could begin as early as 2019 to 2020, the SpaceX satellite development facility in Redmond, Washington, houses the research and development operations for the satellite Internet project.


The communication satellite network SpaceX envisions was publicly announced in January 2015, with the projected capability of supporting the bandwidth to carry up to 50 percent of all backhaul communications traffic and up to 10 percent of local Internet traffic in high-density cities.[3][5] CEO Elon Musk believes that there is significant unmet demand for low-cost global broadband capabilities.[8]

The opening of the SpaceX satellite development facility, in Redmond was announced by SpaceX in January 2015, to build the new communication network. By January 2015, the Seattle-area office planned to initially hire approximately 60 engineers, with the potential to increase to 1,000 people in the next several years.[9] There were 45 open positions in October 2015,[10] the company was operating in 2,800 square meters (30,000 sq ft) of leased space by late 2016, and by January 2017 had taken on a 3,800 square meters (40,625 sq ft) facility, both in Redmond.[11]

By January 2016, the company was planning to have two prototype satellites flying in 2016,[12] and have the initial satellite constellation in orbit and operational by approximately 2020.[5] However, by 2017, design changes had obviated the original two test satellites, and the launch of two revised satellites had slipped to 2018.[13][14]

In July 2016, SpaceX had acquired a 740 square meters (8,000 sq ft) creative space in Irvine, CA (Orange County).[15] SpaceX job listings indicate the office will include signal processing, RFIC, and ASIC development for the satellite program.[16]

By October 2016, SpaceX had developed test-flight satellites that they hoped to launch in 2017 and they were focusing on a significant business challenge of achieving a sufficiently-low-cost design for the user equipment, aiming for something that can ostensibly install easily at end-user premises for approximately US$200. Overall, Shotwell said the project "remains in the design phase as the company seeks to tackle issues related to user-terminal cost."[2] Deployment, if carried out, would not be until "late in this decade or early in the next."[8]

In November 2016, SpaceX filed an application with the FCC for a "non-geostationary orbit satellite system in the Fixed-Satellite Service using the Ku and Ka frequency bands."[17]

By March 2017, SpaceX filed with the FCC plans to field a constellation of more than 7500 "V-band satellites in non-geosynchronous orbits to provide communications services" in an electromagnetic spectrum that has not previously been "heavily employed for commercial communications services." Called the "V-band low-Earth orbit (VLEO) constellation," it would consist of "7,518 satellites to follow the [earlier] proposed 4,425 satellites that would function in Ka- and Ku-band.[18] The March 2017 plan called for SpaceX to launch test satellites of the type in both 2017 and 2018, and begin launching the operational constellation sats in 2019. Full build-out of the constellation is not expected to be completed until 2024, at which time there are expected to be "4,425 satellites into orbit around the Earth, operating in 83 planes, at fairly low altitudes of between 1,110 kilometers and 1,325 kilometers."[19] By September 2017, the planned number of sats in each constellation had not changed, but the altitude of each constellation became explicit: the larger group—7,518 sats—would operate at 340 kilometres (210 mi) altitude, while the smaller group—4,425 sats—would orbit at 1,200 kilometres (750 mi) altitude.[20]

Some controversy arose in 2015–2017 with regulatory authorities on licensing the communications spectrum for these large constellations of satellites. The traditional and historical regulatory rule for satellites licensing comm spectrum has been that satellite operators could "launch a single spacecraft to meet their in-service deadline [from the regulator], a policy seen as allowing an operator to block the use of valuable radio spectrum for years without deploying its fleet."[21] The US regulatory authority has set a six-year deadline to have an entire large constellation deployed to comply with licensing terms, the international regulator, the ITU, proposed in mid-2017 an international guideline that would be considerably less restrictive. In September 2017, both Boeing and SpaceX petitioned the US FCC for a waiver of the 6-year rule.[21]

SpaceX filed legal documents in 2017 seeking to trademark the name Starlink for their satellite broadband network.[22]

By March 2017, SpaceX had filed regulatory paperwork to launch approximately 12,000 satellites, including 7,518 sats to "provide communications in the little used V band in very-low Earth orbit.[4]

SpaceX filed documents in late 2017 with the US FCC to clarify their space debris mitigation plan. SpaceX will "implement an operations plan for the orderly de-orbit of satellites nearing the end of their useful lives (roughly five to seven years) at a rate far faster than is required under international standards. [Satellites] will de-orbit by propulsively moving to a disposal orbit from which they will reenter the Earth's atmosphere within approximately one year after completion of their mission."[23]


Global broadband Internet[edit]

SpaceX has articulated the explicit goal to provide broadband internet connectivity to underserved areas of the planet, as well as provide competitively-priced service to urban areas. Moreover, SpaceX has indicated that the positive cash flow from selling satellite internet services would be necessary to fund SpaceX Mars plans.[24]

In early 2015, two space entrepreneurs announced Internet satellite ventures in the same week; in addition to SpaceX CEO Elon Musk announcing the project that would later be named Starlink, serial-entrepreneur Richard Branson announced an investment in OneWeb, a similar constellation with approximately 700 satellites that had already procured communication frequency licenses for their broadcast spectrum.[9][25]

After the failures of previous satellite-to-consumer space ventures, satellite industry consultant Roger Rusch said in 2015 "It's highly unlikely that you can make a successful business out of this."[9] Musk publicly acknowledged that business reality, and indicated in mid-2015 that while endeavoring to develop this technically-complicated space-based communication system he wants to avoid overextending the company and stated that they are being measured in the pace of development.[26] Nevertheless, internal documents leaked in February 2017 indicate that SpaceX expected more than US$30 billion in revenue by 2025 from its satellite constellation while revenues by its launch business are expected to reach US$5 billion in the same year.[27][28]

In February 2015, financial analysts questioned established geosynchronous orbit communications satellite fleet operators as to how they intend to respond to the competitive threat of SpaceX/Google and OneWeb LEO communication satellites.[29] In October, SpaceX President Gwynne Shotwell indicated that while development continues the business case for the long-term rollout of an operational satellite network is still in an early phase.[10]

In 2015, court documents indicate that SpaceX had engaged in collaboration with wireless chip-maker Broadcom. Five key engineers subsequently left to join SpaceX leading to a lawsuit filed by Broadcom alleging that "SpaceX stole our best minds." In March, an Orange County judge denied Broadcom's multiple restraining order requests.[30]

Extending to use beyond Earth[edit]

In the long-term, SpaceX intends to develop and deploy a version of the satellite communication system that would be used on Mars; in the mid-term, SpaceX is interested in the satcomm system on Earth generating revenue that would be helpful in providing capital for the company's Mars transport project.[8]

Internet communication satellite characteristics[edit]

The Internet communication satellites are expected to be in the smallsat-class of 100-to-500 kg (220-to-1,100 lb)-mass, which are intended to be orbiting at an altitude of approximately 1,100 kilometers (680 mi). Initial plans as of January 2015 were for the constellation to be made up of approximately 4000 cross-linked[26] satellites, more than twice as many operational satellites as were in orbit in January 2015.[5]

The satellites will employ optical inter-satellite links and phased array beam forming and digital processing technologies in the Ku- and Ka-band according to documents filed with the U.S. Federal Communications Commission (FCC).[31][32] 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 other than that they will utilize frequencies above 10,000 GHz.[33]

The satellites would be mass-produced, at 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."[34] "In order to revolutionize space, we have to address both satellites and rockets."[5] "Smaller satellites are crucial to lowering the cost of space-based Internet and communications."[9]

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 (NGSO) 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."[35]

The system will not compete with Iridium satellite constellation, which is designed to link directly to handsets. Instead, it will be linked to flat user terminals the size of a pizza box, which will have phased array antennas and track the satellites, the terminals can be mounted anywhere, as long as they can see the sky.[26]

While internet via a geostationary satellite has a latency of no less than 240 ms, the lower latency limit for Starlink orbiting at 1100 km is only 3% of that, about 7 ms.

The system will use a peer-to-peer protocol simpler than IPv6.[36]

Prototype development and testing[edit]

SpaceX began flight testing their satellite technologies in 2018,[13] with the launch of two test satellites, the two identical satellites were called MicroSat-1a and MicroSat-1b during development but were renamed Tintin A and Tintin B upon orbital deployment in February 2018.

The satellites orbit in a circular low Earth orbit at 625 kilometers (388 mi) altitude in a high-inclination orbit for a planned six to twelve-month duration. The satellites will communicate with three testing ground stations in Washington and California for short-term experiments of less than ten minutes duration, roughly daily.[12][37] Both microsats were originally slated to be launched into 625 km circular orbits at approximately 86.4 degrees inclination, and to include panchromatic video imager cameras to film image of Earth and the satellite.[38]

At the time of the June 2015 announcement, SpaceX had stated plans to launch the first two demonstration satellites in 2016,[12] but the target date was subsequently moved out to 2018,[13] as of October 2015, MicroSat-1a and 1b were planned to be the first of up to eight[38] prototype satellites to be flown before deployment of the operational constellation.[39] The initial two test satellites were successfully launched to a sun-synchronous low Earth orbit on 22 February 2018, and were renamed Tintin A and Tintin B.[6][40] Further test satellite plans have not been announced.

Competition and market effects[edit]

In addition to the OneWeb constellation, announced nearly concurrently with the SpaceX constellation, a 2015 proposal from Samsung has outlined a 4600-satellite constellation orbiting at 1,400 kilometers (900 mi) that could provide a zettabyte per month capacity worldwide, an equivalent of 200 gigabytes per month for 5 billion users of Internet data.[41][42]

By October 2017, the expectation for large increases in satellite network capacity from emerging lower-altitude broadband constellations caused market players to cancel investments in new geosynchronous orbit broadband commsats.[43]

See also[edit]

  • Globalstar - a low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications
  • Iridium satellite constellation – an operational constellation of 66 active LEO satellites used to provide global satellite phone service
  • OneWeb satellite constellation – a proposed LEO satellite constellation to provide global Internet broadband service to individual consumers as early as 2019
  • ORBCOMM – an operational constellation used to provide global asset monitoring and messaging services from its constellation of 29 LEO communications satellites orbiting at 775 km
  • Teledesic – a former (1990s) venture to accomplish broadband satellite Internet services
  • ViaSat Communications – offers an operational Internet service from four geostationary satellites
  • Laser communication in space – key technology used to establish the inter-satellite links of the Starlink constellation


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