Starlink

Starlink is a satellite constellation being constructed by SpaceX[1][2] to provide satellite Internet access.[3][4] The constellation will consist of thousands of mass-produced small satellites in low Earth orbit (LEO), working in combination with ground transceivers. SpaceX also plans to sell some of the satellites for military,[5] scientific, or exploratory purposes.[6]

Starlink
60 Starlink satellites stacked together before deployment on May 24, 2019.
ManufacturerSpaceX
Country of originUnited States
OperatorSpaceX
ApplicationsInternet service
Specifications
Spacecraft typeSmall satellite
Launch mass227–260 kg (500–573 lb)
EquipmentKu and Ka band phased array antennas
Hall-effect thrusters
RegimeLow Earth
(335.9–1,325 km, 208.7–823.3 mi)
Production
StatusActive
Launched422
Maiden launchFebruary 22, 2018
Last launchApril 22, 2020

Concerns have been raised about the long-term danger of space debris resulting from placing thousands of satellites in orbits above 600 km (370 mi)[7][8] and a possible impact on astronomy,[9] although the Starlink satellites orbit at 550 km (340 mi)[10] and SpaceX is reportedly attempting to solve the latter issue. On Starlink 2, one of the satellites has an experimental coating to make it less reflective, and thus impact ground-based astronomical observations less.[11]

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.[12] 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 May 24, 2019 UTC when the first 60 operational satellites were launched.[1][13] The SpaceX satellite development facility in Redmond, Washington, houses the Starlink research, development, manufacturing, and on-orbit control operations.

As of April 22, 2020 – with 417 satellites[14] of the constellation in orbit[15] – SpaceX is targeting service in the Northern U.S. and Canada by late 2020. SpaceX is launching 60 satellites at a time, aiming to deploy 1,584 of the 250 kg (550 lb) spacecraft to provide near-global service by late 2021 or 2022.[16] However, these are only internal projections and not set dates.

History

2015–2017
The SpaceX satellite development facility, Redmond, Washington, in use from 2015 to mid-2018.

The communication satellite network SpaceX envisions was publicly announced in January 2015, with the projected design capability to support sufficient bandwidth to carry up to 50% of all backhaul communications traffic, and up to 10% of local Internet traffic, in high-density cities.[4][6] CEO Elon Musk said that there is significant unmet demand for low-cost global broadband capabilities.[17]

The opening of the SpaceX satellite development facility in Redmond was announced by SpaceX in January 2015 with partners, to develop and build out the new communication network. At the time, the Seattle-area office planned to initially hire approximately 60 engineers, and potentially 1,000 people by 2018.[18] The company operated in 2,800 m2 (30,000 sq ft) of leased space by late 2016, and by January 2017 had taken on a 3,774.2 m2 (40,625 sq ft) second facility, both in Redmond.[19] In August 2018, SpaceX consolidated all their Seattle-area operations with a move to a larger three-building facility at Redmond Ridge Corporate Center to support satellite manufacturing in addition to R&D.[20]

In July 2016, SpaceX acquired a 740 m2 (8,000 sq ft) creative space in Irvine, California (Orange County).[21] SpaceX job listings indicated the Irvine office would include signal processing, RFIC, and ASIC development for the satellite program.[22]

By January 2016, the company had publicly disclosed plans to have two prototype satellites flying in 2016,[23] and to have the initial satellite constellation in orbit and operational by approximately 2020.[6] By October 2016, SpaceX had developed the initial satellites that they hoped to launch and test in 2017, but the satellite division was focusing on a significant business challenge of achieving a sufficiently low-cost design for the user equipment, aiming for something that ostensibly can be installed easily at end-user premises for approximately US$200. Overall, SpaceX President Gwynne Shotwell said then that the project remained in the "design phase as the company seeks to tackle issues related to user-terminal cost."[3] Deployment, if carried out, would not be until "late in this decade or early in the next".[17] The two original test satellites were not flown and were used only in ground testing. The planned launch of two revised satellites was moved to 2018.[24][25]

In November 2016, SpaceX filed an application with the Federal Communications Commission (FCC) for a "non-geostationary orbit (NGSO) satellite system in the Fixed-Satellite Service using the Ku and Ka frequency bands".[26]

By March 2017, SpaceX filed plans with the FCC to field a second orbital shell of more than 7,500 "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 "Very-Low Earth Orbit (VLEO) constellation",[27] it would comprise 7,518 satellites and would orbit at just 340 km (210 mi) altitude,[28] while the smaller, originally - planned group of 4,425 satellites would operate in the Ka - and Ku-bands and orbit at 1,200 km (750 mi) altitude.[27][28] SpaceX's plans were unusual in two areas: the company intended to utilize the little-used V-band of the communications spectrum, and they intended to use a new orbital regime, the very-low Earth orbit regime of ~340 km (210 mi) altitude, where atmospheric drag is quite high, which normally results in short orbital lifetimes.[29] The March 2017 plan called for SpaceX to launch test satellites of the initial Ka/Ku type in both 2017 and 2018, and begin launching the operational constellation in 2019. Full build-out of the approximately 1,200 km (750 mi) constellation of around 4,440 satellites was not then expected to be completed until 2024.[30]

Some controversy arose in 2015–2017 with regulatory authorities on licensing of the communications spectrum for these large constellations of satellites. The traditional and historical regulatory rule for the licensing spectrum has been that satellite operators could "launch a single spacecraft to meet their in-service deadline [from the regulator], a policy is seen as allowing an operator to block the use of valuable radio spectrum for years without deploying its fleet".[31] By 2017, the FCC had set a six-year deadline to have an entire large constellation deployed to comply with licensing terms. The international regulator, International Telecommunication Union (ITU), proposed in mid-2017 a guideline that would be considerably less restrictive. In September 2017, both Boeing and SpaceX petitioned the US FCC for a waiver of the six-year rule,[31] but they were denied. By 2019, the FCC had ruled that half of the constellation must be in orbit in six years, with the full system in orbit nine years from the date of the license.[32]

SpaceX trademarked the name Starlink for their satellite broadband network in 2017;[33] the name was inspired by the book The Fault in Our Stars.[34]

SpaceX filed documents in late 2017 with the FCC to clarify their space debris mitigation plan. The company 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".[35] In March 2018, the FCC issued SpaceX approval, with some conditions. SpaceX would need to obtain a separate approval from the International Telecommunication Union.[36][37] The FCC supported a NASA request to ask SpaceX to achieve an even higher level of de-orbiting reliability than the standard that NASA had previously used for itself: reliably de-orbiting 90% of the satellites after their missions are complete.[38]

2018–2019

In May 2018, SpaceX expected the total cost of development and buildout of the constellation to approach US$10 billion.[12] In mid-2018, SpaceX reorganized the satellite development division in Redmond, and terminated several members of senior management.[20]

In November 2018, SpaceX received US regulatory approval to deploy 7,518 broadband satellites, in addition to the 4,425 approved earlier. SpaceX's initial 4,425 satellites had been requested in the 2016 regulatory filings to orbit at altitudes of 1,110 km (690 mi) to 1,325 km (823 mi), well above the International Space Station. The new approval was for the addition of a very-low Earth orbit non-geostationary satellite orbit constellation, consisting of 7,518 satellites operating at altitudes from 335 km (208 mi) to 346 km (215 mi), below the ISS.[39] Also in November, SpaceX made new regulatory filings with the US Federal Communications Commission (FCC) to request the ability to alter its previously granted license in order to operate approximately 1,600 of the 4,425 Ka-/ Ku-band satellites approved for operation at 1,150 km (710 mi) in a "new lower shell of the constellation" at only 550 km (340 mi) orbital altitude.[40][41] These satellites would effectively operate in a third orbital shell, a 550 km (340 mi) orbit, while the higher and lower orbits at approximately 1,200 km (750 mi) and approximately 340 km (210 mi) would be used only later, once a considerably larger deployment of satellites becomes possible in the later years of the deployment process. The FCC approved the request in April 2019, giving approval to place nearly 12,000 satellites in three orbital shells: initially approximately 1,600 in a 550 km (340 mi) - altitude shell, and subsequently placing approximately 2,800 Ku- and Ka-band spectrum satellites at 1,150 km (710 mi) and approximately 7,500 V-band satellites at 340 km (210 mi).[32]

With plans by several providers to build commercial space-Internet mega-constellations of thousands of satellites increasingly likely to become a reality, the US military began to perform test studies in 2018 to evaluate how the networks might be used. In December, the US Air Force issued a US$28 million contract for specific test services on Starlink.[42]

In February 2019, a sister company of SpaceX, SpaceX Services, Inc., filed a request with the FCC to request a license for the operation of up to a million fixed satellite earth stations that would communicate with its non-geostationary orbit satellite (NGSO) Starlink system.[43]

By April 2019, SpaceX was transitioning their satellite efforts from research and development to manufacturing, with the planned first launch of a large batch of satellites to orbit, and the clear need to achieve an average launch rate of "44 high-performance, low-cost spacecraft built and launched every month for the next 60 months" to get the 2,200 satellites launched to support their FCC spectrum allocation license assignment.[44] SpaceX said they will meet the deadline of having half the constellation "in orbit within six years of authorization… and the full system in nine years".[32]

By the end of June 2019, SpaceX had communicated with all 60 satellites but lost contact with three; the remaining 57 were working as intended. Forty-five satellites had reached their final orbital altitude of 550 km (340 mi), five were still raising their orbits, and another five were undergoing systems checks before they raise their orbits. The remaining two satellites were intended to be quickly removed from orbit and reenter the atmosphere in order to test the satellite de-orbiting process; the three that lost contact were also expected to reenter, but will do so passively from atmospheric drag as SpaceX was no longer able to actively control them.[45]

In June 2019, SpaceX applied to the FCC for a license to test up to 270 ground terminals – 70 nationwide across the United States and 200 in Washington state at SpaceX employee homes[46][47] – and aircraft-borne antenna operation from four distributed US airfields; as well as five ground-to-ground test locations.[48][49]

By September 2019, SpaceX had gone back to the FCC to apply for more changes to the orbital constellation. SpaceX asked to triple the number of orbital planes in the 550 km (340 mi) orbital shell, from 24 to 72, arguing that they could then place satellites into multiple planes from a single launch. SpaceX argued that this change could bring coverage to the southern US in time for the 2020 hurricane season.[50] The change was approved in December 2019, and will now see only 22 satellites in each plane rather than the 66 that had been a part of the original design. The total number of satellites in the 550 km shell would remain the same, at 1,584.[51]

The Starlink-1 mission deploying the first 60 operational satellites was lauched aboard a Falcon 9 rocket from Cape Canaveral Air Force Station, Florida on November 11, 2019.

In October 2019, Elon Musk publicly tested the Starlink network by using an internet connection routed through the network to post a tweet to social media site Twitter.[52]

2020–2021

As of April 22, 2020, SpaceX has launched 422 Starlink satellites. They plan to launch 60 more per Falcon 9 flight, with launches as often as every two weeks in 2020. In total, nearly 12,000 satellites are planned to be deployed, with a possible later extension to 42,000.[53] The initial 12,000 satellites are planned to orbit in three orbital shells: first placing approximately 1,584 in a 550 km (340 mi) altitude shell, then approximately 2,825 Ku-band and Ka-band spectrum satellites at 1,110 km (690 mi), and approximately 7,500 V-band satellites at 340 km (210 mi).[32]

On April 17, 2020, SpaceX has modified the architecture of the Starlink network. SpaceX submitted an application to the Federal Communications Commission (FCC) proposing to operate more satellites in lower orbits than the FCC previously authorized. The first phase will include 1,584 satellites orbiting at 550 km (340 mi) in planes inclined 53.0°. That part of the constellation, for launch through the end of 2020, remains unchanged.[54]

Satellites from the SpaceX Starlink 6 mission passing over Breuil-Cervinia, Italy on 24 April 2020 and visible with a naked eye.

SpaceX previously had regulatory approval from the FCC to operate another 2,825 satellites in higher orbits between 1,110 km (690 mi) and 1,325 km (823 mi), in orbital planes inclined at 53.8°, 70.0°, 74.0° and 81.0°. The modified plan submitted to the FCC by SpaceX foresees Ku-band and Ka-band satellites in the next phase of the Starlink network all operated at altitudes between 540 km (340 mi) and 570 km (350 mi) at inclinations of 53.2°, 70.0° and 97.6°. The application covers 4,408 Starlink satellites, one fewer than envisioned under the previous architecture. SpaceX plans to launch another 7,500 V-band into orbits around 345 km (214 mi)[54]

Launches

The deployment of the first 1,584 satellites will be into 72 orbital planes of 22 satellites each, with a requested lower minimum elevation angle of beams to improve reception: 25° rather than the 40° of the other two orbital shells.[40]:17 SpaceX launched the first 60 satellites of the constellation in May 2019 into a 450 km (280 mi) orbit and expected up to six launches in 2019 at that time, with 720 satellites. (12 × 60) for continuous coverage in 2020.[55][56]

In August 2019, SpaceX expected four more launches in 2019[57] and at least nine launches in 2020.[58]

SpaceX expects 24 Starlink launches in 2020.[59] In March 2020, SpaceX reported producing six satellites per day.[60]

Starlink satellites are also planned to launch on Starship, an under-development rocket of SpaceX that will launch 400 satellites at a time.[61]

List of launches
List of launches
Flight No. Mission Date and time (UTC) Launch site Launch vehicle[lower-alpha 1] Orbit altitude Inclination Number deployed Version Outcome
1 Tintin February 22, 2018, 14:17[62][63] Vandenberg, SLC-4E F9 FT ♺ B1038.2[64] 514 km (319 mi) 97.5°[65] 2 – Success
Two test satellites known as Tintin A and B[66] (MicroSat-2a and 2b) that were deployed as co-payloads to the Paz satellite. The two prototypes are now being deorbited.[14]
2 Starlink v0.9 May 24, 2019, 02:30[67] CCAFS, SLC-40 F9 B5 ♺ B1049.3[64] 440–550 km (270–340 mi)[68] 53° 60[69][70] v0.9 Success[71]
Second launch of test satellites for SpaceX's Starlink constellation.[32] Said to be "production design", these are used to test various aspects of the network, including deorbiting.[72] They do not yet have the planned satellite interlink capabilities and they only communicate with antennas on Earth. A day after launch an amateur astronomer in the Netherlands was one of the first to publish a video showing the satellites flying across the sky as a "train" of bright lights.[73] By five weeks post launch, 57 of the 60 satellites were "healthy" while 3 had become non-operational and were derelict, but will deorbit due to atmospheric drag.[74] As of October 31, 2019, 49 satellites were in the target 550 km orbit while the others were still raising their orbits.[68]
3 Starlink 1 November 11, 2019, 14:56[75] CCAFS, SLC-40 F9 B5 ♺ B1048.4 550 km (340 mi) (target) 53° 60[76] v1.0 Success
Second large batch of satellites, first operational flight (v1.0),[77] v1.0 does not have laser links yet.[78]
4 Starlink 2 January 7, 2020, 02:19[79] CCAFS, SLC-40 F9 B5 ♺ B1049.4 550 km (340 mi) 53° 60 v1.0 Success
Third large batch of satellites.[79] One of the satellites, dubbed DarkSat,[54] has an experimental coating to make it less reflective, and thus impact ground-based astronomical observations less.[80]
5 Starlink 3 January 29, 2020, 14:06[79] CCAFS, SLC-40 F9 B5 ♺ B1051.3 550 km (340 mi) 53° 60 v1.0 Success
Fourth large batch of satellites.[79][81]
6 Starlink 4 February 17, 2020, 15:05[79] CCAFS, SLC-40 F9 B5 ♺ B1056.4 550 km (340 mi) 53° 60 v1.0 Success
Fifth large batch of satellites.[82]
7 Starlink 5 March 18, 2020, 12:16:39[83] KSC, LC-39A F9 B5 ♺ B1048.5 550 km (340 mi) 53° 60 v1.0 Success
The sixth Starlink launch overall and the fifth operational batch of Starlink satellites.[84]
8 Starlink 6 April 22, 2020, 19:30:30[85] KSC, LC-39A F9 B5 ♺ B1051.4 550 km (340 mi) 53° 60 v1.0 Success
The seventh Starlink launch overall and the sixth operational batch of Starlink satellites.[86]
9 Starlink 7 Early-to-mid May [87] CCAFS, SLC-40 F9 B5 ♺ 550 km (340 mi) 53° 60 v1.0 Planned
The eighth Starlink launch overall and the seventh operational batch of Starlink satellites. All satellites are to have sunshades, and thus impact ground-based astronomical observations less, on the ninth launch.[14][88]

Services

Global broadband Internet

SpaceX intends to provide satellite internet connectivity to underserved areas of the planet, as well as provide competitively priced service to urban areas. The company has stated that the positive cash flow from selling satellite internet services would be necessary to fund their Mars plans.[89]

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 planned satellites that had already procured communication frequency licenses for their broadcast spectrum.[18][90]

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".[18] Musk publicly acknowledged that business reality, and indicated in mid-2015 that while endeavoring to develop this technically complicated space-based communication system he wanted to avoid overextending the company, and stated that they are being measured in their pace of development.[91] Nevertheless, internal documents leaked in February 2017 indicated that SpaceX expected more than US$30 billion in revenue by 2025 from its satellite constellation, while revenues from its launch business were expected to reach US$5 billion in the same year.[92][93]

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 and OneWeb LEO communication satellites.[94] In October, SpaceX President Gwynne Shotwell indicated that while development continues, the business case for the long-term rollout of an operational satellite network was still in an early phase.[95]

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.[96]

With the initial launch of the first 60 satellites of the operational constellation in 2019, SpaceX indicated that it would require 420 satellites in the constellation to achieve minor broadband coverage of Earth, and 780 of the first ~1,600 to provide moderate coverage.[70]

On April 17, 2020, in documentation to the FCC, SpaceX said lower altitude will put the satellites closer to Starlink consumers and allow the network "to provide low-latency broadband to unserved and underserved Americans that is on par with service previously only available in urban areas". The change will also improve service for U.S. government users in polar regions and allow for more rapid deployment of the network, SpaceX said. In lower orbits will help ensure they re-enter the atmosphere a shorter time in case of failure. And will broadcast signals at reduced power levels because they are closer to Earth, which SpaceX said will allow the fleet to be compliant with limits to reduce radio interference with other satellite and terrestrial wireless networks.[54]

Use beyond Earth

SpaceX has long-term plans to develop and deploy a version of the satellite communication system to serve Mars.[17]

Technology

Constellation design and status
The Starlink constellation, phase 1, first orbital shell: 72 orbits with 22 each, 1,584 satellites at 550 km altitude.
Phase Orbit shells
(km)		 Number of
satellites		 Inclination
(degrees)		 Half size contractual
completion time		 Full size contractual
completion time		 Satellites deployed
(April 22, 2020)		 Retired satellites
(April 24, 2020)		 Dead satellites
(April 24, 2020)
1
 550 1,584 53.0 March 2024 March 2027 420 15[97] 9[97]
1,110 1,600 53.8 0
1,130 400 70.0 0
1,275 374 74.0 0
1,325 450 80.0 0
2
 335.9 2,493 42.0 November 2024 November 2027 0
340.8 2,478 48.0 0
345.6 2,547 53.0 0

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 km (680 mi), according to early public releases of information in 2015. In the event, the first large deployment of 60 satellites in May 2019 were 227 kg (500 lb)[67] and SpaceX decided to place the satellites at a relatively low 550 km (340 mi), due to concerns about the space environment.[98] Initial plans as of January 2015 were for the constellation to be made up of approximately 4,000 cross-linked[91] satellites, more than twice as many operational satellites as were in orbit in January 2015.[6]

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).[99][100] 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.[101] Early satellites are launched without laser links, in October 2019 SpaceX expected satellites with these links to be ready by the end of 2020.[102]

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".[103] "In order to revolutionize space, we have to address both satellites and rockets".[6] "Smaller satellites are crucial to lowering the cost of space-based Internet and communications".[18]

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".[104]

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.[105] The system will use a peer-to-peer protocol claimed to be "simpler than IPv6", it will also incorporate end-to-end encryption natively.[106] However, no details on this have been released as of yet.

Starlink satellites use Hall-effect thrusters with krypton gas as the reaction mass[67][107] for orbit raising and station keeping.[108] 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.[109]

User terminals

The system will not directly connect from its satellites to handsets (unlike the constellations from Iridium, Globalstar, Thuraya and Inmarsat). 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.[91]

In 2019, tests by the U.S. Air Force Research Laboratory (AFRL) demonstrated a 610 megabit per second data link through Starlink to a Beechcraft C-12 Huron aircraft in flight.[110]

Satellite revisions

At the time of the June 2015 announcement, SpaceX had stated plans to launch the first two demonstration satellites in 2016,[23] but the target date was subsequently moved out to 2018.[24] SpaceX began flight testing their satellite technologies in 2018[24] with the launch of two test satellites. The two identical satellites were called "MicroSat-2a" and "MicroSat-2b"[111] 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.[112]

MicroSat-1a and MicroSat-1b were originally slated to be launched into 625 km (388 mi) circular orbits at approximately 86.4° inclination, and to include panchromatic video imager cameras to film images of Earth and the satellite.[113]

Tintin A and B were inserted into a 514 km (319 mi) orbit. Per FCC filings,[114] they were intended to raise themselves to an 1,125 km (699 mi) orbit, the operational altitude for Starlink LEO satellites per the earliest regulatory filings, but stayed close to their original orbits. SpaceX announced in November 2018 that they would like to operate an initial shell of about 1,600 satellites in the constellation at about 550 km (340 mi) orbital altitude, at an altitude similar to the orbits Tintin A and B stayed in.[40]

The satellites currently orbit in a circular low Earth orbit at about 500 km (310 mi) altitude[115] 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.[23][116]

The 60 Starlink v0.9 satellites, launched May 2019, have the following characteristics:[67]

  • Flat-panel design with multiple high-throughput antennas and a single solar array
  • Mass: 227 kg (500 lb)
  • Hall-effect thrusters using krypton as the reaction mass, for position adjustment on orbit, altitude maintenance and deorbit
  • Star tracker navigation system for precision pointing
  • Able to use Department of Defense-provided debris data to autonomously avoid collision[117]
  • Operational altitude of 550 km (340 mi)
  • 95% of "all components of this design will quickly burn in Earth’s atmosphere at the end of each satellite's lifecycle"

The Starlink v1.0 satellites, launched since November 2019, have the additional following characteristics:

  • 100% of "all components of this design will quickly burn in Earth's atmosphere at the end of each satellite's lifecycle"
  • Ka-band added
  • Mass: 260 kg
  • One of them, numbered 1130 and called DarkSat, has its albedo reduced

Competition and market effects

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,[118][119] 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.[120] 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[121] with Amazon's previously announced large network of twelve satellite ground station facilities (the "AWS Ground Station unit") announced in November 2018.[122]

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.[123]

Criticism
Starlink in Tübingen
A batch of Starlink satellites as seen from the International Space Station.

The large number of planned satellites has been met with criticism from the astronomical community because of concerns for light pollution.[124][125][126] 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 (IAU) and National Radio Astronomy Observatory (NRAO) have released official statements expressing concern on the matter.[9][127]

SpaceX representatives and Musk have claimed that the satellites will have minimal impact.[128] 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.[129][130][131][132] 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.[133][134] To date, only one Starlink satellite (Starlink 1130-Darksat) has experimental coating to reduce its albedo. However the reduction in magnitude is very subtle with only 0.8 magnitude reduction, and this is not sufficient for astronomers.[135][136]

"Beyond this (darkening) treatment, SpaceX is developing new mitigation efforts that it plans to test in the coming months", SpaceX wrote in Federal Communications Commission (FCC) filing, on 17 April 2020. "Additionally, SpaceX will make satellite tracking data available so astronomers can better coordinate their observations with our satellites". Another change from SpaceX is studying the addition of a sunshade, or visor, to unfurl like an umbrella on Starlink satellites to reduce the amount of sunlight glinting off the spacecraft. Musk tweeted Wednesday that SpaceX is taking "key steps to reduce satellite brightness". He wrote that the satellites "should be much less noticeable" when they are flying at lower altitudes soon after launch. SpaceX is changing the angle of each satellite's solar panel, and all of the Starlink satellites will have sunshades beginning with the ninth launch of the fleet. That launch is expected in a couple of months.[14]

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.[8][137][138] However the risk of collision is not negligible, and despite Elon Musk's willingness to tweak the orientation of a satellite on demand, SpaceX did not move a satellite that came within a 1 in 1000 collision probability with the European one, ten times higher than ESA's threshold for avoidance maneuvers.[139]

See also
  • Globalstar – an operational low Earth orbit (LEO) satellite constellation for satellite phone and low-speed data communications
  • Iridium satellite constellation – an operational constellation of LEO satellites for global satellite phone service
  • Kuiper Systems – a planned 3236 LEO satellite Internet constellation being built by an Amazon subsidiary[140]
  • Laser communication in space – key technology used to establish the inter-satellite links of the Starlink constellation
  • O3b Networks – medium Earth orbit (MEO) satellite constellation primarily intended to provide voice and data to mobile operators and Internet service providers, and is a wholly-owned subsidiary of SES S.A.
  • OneWeb satellite constellation – an under-construction (but bankrupt as of March 2020) LEO satellite constellation, to provide global Internet broadband service to individual consumers from 2020
  • 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 – offers an operational Internet service from four geostationary satellites

Notes
  1. Falcon 9 first-stage boosters are designated with a construction serial number and an optional flight number when reused, e.g. B1021.1 and B1021.2 represent the two flights of booster B1021. Launches using reused boosters are denoted with a recycled symbol (♺).

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