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Starlink (satellite constellation)

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Starlink is a satellite constellation development project underway by SpaceX,[1] 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 submitted regulatory filings to launch nearly 12,000 satellites to orbit by the mid-2020s.[4] SpaceX also plans to sell satellites that use a satellite bus that may be used for military, scientific or exploratory purposes.[5] In November 2018 SpaceX received FCC approval to deploy 7,518 broadband satellites, in addition to the 4,425 satellites that were approved in March 2018. [6]

Development began in 2015, and prototype test-flight satellites were launched on 22 February 2018.[7][8] Initial operation of the constellation could begin in 2020 with satellite deployment beginning mid 2019.[9] The SpaceX satellite development facility in Redmond, Washington, houses the research and development operations for the satellite Internet project.

Contents

HistoryEdit

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% of all backhaul communications traffic and up to 10% 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.[10]

 
SpaceX original satellite development facility, Redmond, Washington. Used 2015–mid-2018

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, and potentially 1,000 people in the next several years.[11] There were 45 open positions in October 2015.[12] The company operated 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.[13]

By January 2016, the company was planning to have two prototype satellites flying in 2016,[14] and have the initial satellite constellation in orbit and operational by approximately 2020.[5] However, by 2017, design changes obviated the original two test satellites, and the launch of two revised satellites had slipped to 2018.[15][16]

In July 2016, SpaceX had acquired a 740 square meters (8,000 sq ft) creative space in Irvine, CA (Orange County).[17] SpaceX job listings indicate the office will include signal processing, RFIC, and ASIC development for the satellite program.[18]

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."[10]

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."[19]

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.[20] 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."[21] 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.[22]

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."[23] 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, International Telecommunication Union, 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.[23]

SpaceX filed legal documents in 2017 seeking to trademark the name Starlink for their satellite broadband network.[24]

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."[25]

In March 2018 the FCC issued SpaceX approval with some conditions. SpaceX will need a separate approval from the ITU.[26][27] The FCC did agree with NASA for requiring a higher de-orbiting reliability than the NASA's regular standard of reliably deorbiting 90% of the satellites after their missions are complete.[28] In May 2018, SpaceX expected the total cost of development and buildout of the constellation to approach US$10 billion.[29]

In mid-2018, SpaceX reorganized the satellite development division in Redmond, and fired several senior management in the process.[30] They also consolidated all their Seattle-area operations with a move to Redmond Ridge Corporate Center,[30] leaving the facility they started work in during 2015.

In November 2018, SpaceX received US approval to deploy 7,518 broadband satellites, in addition to the 4,425 satellites that were approved earlier. SpaceX's initial 4,425 satellites are expected to orbit at altitudes of 1,110 km to 1,325 km, well above the ISS. The new approval is for the proposal to add a very-low Earth orbit NGSO [non-geostationary satellite orbit] constellation, consisting of 7,518 satellites operating at altitudes from 335 km to 346 km. [31] Also in November, SpaceX made regulatory filings with the US FCC to request the ability to alter its previously granted license to operate approximately 1500 of the 4,425 satellites approved for operation at 1,150 km (710 mi) to a "new lower shell of the constellation" to only 550 km (340 mi) orbital altitude.[32][33]

ServicesEdit

Global broadband InternetEdit

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.[34]

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.[11][35]

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."[11] 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.[36] 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.[37][38]

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.[39] 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.[12]

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.[40]

Extending to use beyond EarthEdit

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.[10]

Satellite hardwareEdit

The Internet communication satellites are expected to be in the smallsat-class of 100-to-500 kg (220-to-1,100 lb)-mass, which were intended to be in Low Earth Orbit (LEO) at an altitude of approximately 1,100 kilometers (680 mi). However, SpaceX ultimately decided to keep the satellites at a relatively low 550 kilometers (340 mi), due to concerns about the space environment.[41] Initial plans as of January 2015 were for the constellation to be made up of approximately 4000 cross-linked[36] 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).[42][43] 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.[44]

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."[45] "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."[11]

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."[46]

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.[36]

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 offer latencies of 600 ms or more. Starlink satellites would orbit at 1/30 to 1/105 of geostationary orbits, and thus offer more practical latencies of around 7 to 30 ms, comparable to or exceeding existing cable or fiber networks.[47]

The system will use a peer-to-peer protocol claimed to be "simpler than IPv6"[48], though no details have been as yet released.

Prototype development and testingEdit

SpaceX began flight testing their satellite technologies in 2018,[15] with the launch of two test satellites. The two identical satellites were called MicroSat-2a and MicroSat-2b[49] during development but were renamed Tintin A and Tintin B upon orbital deployment in February 2018. Two previously manufactured satellites, MicroSat-1a and MicroSat-1b were meant to be launched together as secondary payloads on one of the Iridium-NEXT flights, but they were instead used for ground-based tests.[50]

MicroSat 1a & 1b 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.[51].

MicroSat 2a&2b were inserted into a 514km orbit. Per FCC filings[52] they were intended to raise themselves to an 1125km orbit. This is the operational altitude for StarLink LEO satellites. For unknown reasons the satellites have not moved to the higher orbit.

The satellites currently orbit in a circular low Earth orbit at about 500 kilometers (310 mi) altitude[53] 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.[14][54]

At the time of the June 2015 announcement, SpaceX had stated plans to launch the first two demonstration satellites in 2016,[14] but the target date was subsequently moved out to 2018.[15] As of October 2015, MicroSat-2a and 2b were planned to be the first of up to eight[51] prototype satellites to be flown before deployment of the operational constellation.[55] 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.[7][56] In October 2018 SpaceX confirmed that the test satellites were working as expected and announced mid 2019 as target for initial launches of the constellation.[9]

Competition and market effectsEdit

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, or 77 kilobytes per second, for 5 billion users of Internet data.[57][58] Telesat announced a smaller 117 satellite constellation and plans to deliver initial service in 2021.[59]

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.[60]

See alsoEdit

  • 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

ReferencesEdit

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External linksEdit