Starlink

from Wikipedia, the free encyclopedia
logo

Starlink is a global satellite network planned by the US space company SpaceX under Elon Musk and Gwynne Shotwell , which will offer Internet access in North America from the end of 2020 , and then almost worldwide in 2021. There are now more than 650 Starlink satellites in earth orbit , making SpaceX the world's largest commercial satellite operator . In total, there are limited approvals for the launch of a maximum of 11,927 satellites until 2027, as well as applications from SpaceX for up to another 30,000 satellites. Taken together, this corresponds to five times the total of all satellites launched between 1957 ( Sputnik 1 ) and 2019.

Planned network structure

In a first stage height are provided up to 1,584 satellite in 550 kilometers in which each satellite 22 to 72 orbital planes with 53 ° inclination to be distributed. In the second step, up to 2,825 more copies will follow at an altitude of 540–570 km. In the third step SpaceX wants to 7,518 satellites in polar orbits carry in 340 kilometers altitude. The requests for 30,000 additional satellites relate to stations from 328 to 580 kilometers. The advantages of the low altitude are short signal propagation times in the data connections of the users, and with the two lower orbits also an independent removal of the space debris after a possible failure of the maneuverability of one or more satellites.

The satellites continuously pass on their responsibility for an area to other satellites. The satellites are to be networked with one another using a technology called Laserlink , so that data can be exchanged without contact with a ground station .

The system is intended to provide high-speed internet (according to outdated documents from 2016 with up to 1 Gbit / s per user). The total usable capacity of the system should be around 1 Terabit / s per 60 satellites, which corresponds to around 3,300 Gigabyte / s in the first expansion stage. From 1,000 satellites, it should be economically profitable.

Satellite technology

Two stacks with a total of 60 Starlink satellites on a Falcon 9 upper stage

The Starlink satellites have (at least for sure in the first generation) a comparatively unusual, extremely flat design. This allows them to be stacked on top of each other when starting, which saves weight and space compared to conventional launch brackets. The satellites use four phased array antennas and a Hall drive with krypton gas , which is cheaper than the commonly used xenon . Using optical sensors and access to the space object database of the North American Aerospace Defense Command , the Starlink satellites should be able to avoid space debris independently . The service life of the first generation of satellites is designed for five years; after that, further developed satellites will be used.

The data transmission takes place in K u and K a frequency bands. As the communication bandwidth of the first generation of satellites, Elon Musk specified around 33-66 gigabits per second and satellite. Due to geographical conditions, only part of it can be used.

Starlink satellite specifications
Parameter Version 0.9 Version 1.0
description Flat panel design
Power supply 1 × solar array
Dimensions 227 kg 260 kg
Lane control and re-entry Hall drives with krypton gas
Position control 1 × reaction wheel
Alignment Star tracker
communication additional 1 × K a band antenna
The components burn up on re-entry 95% 100%

Terminals

SpaceX produces its own terminals for the users of the system. These have a phased array antenna with a diameter of 48 cm, which is mounted on a rod, mechanically aligned and electronically tracked with electric motors . In March 2020, the company received a general license to operate one million of these devices in the USA.

expansion

On February 22, 2018, a Falcon 9 launched the two Starlink test satellites Tintin A and Tintin B into space alongside the Spanish Earth observation satellite Paz . The two satellites are 1.1 meters by 0.7 meters by 0.7 meters and weigh 400 kilograms. On board they have a control computer, a drive, systems for position and attitude regulation and communication systems for the communication between the satellites. They communicated with a total of seven ground stations, and only for about a quarter of an hour a day so as not to disrupt other radio communications . The test should run for about 20 months.

Orbit maneuvers of the first 6 × 60 Satelink satellites, November 2019 to April 2020 ( animated graphics )

A pre-series of 60 satellites was launched in May 2019. The planned laser interlinks , which were announced for the end of 2020, are still missing for these prototypes . They were released at an altitude of 440 km; from there, 53 of the satellites moved independently into their target orbit at 550 km. Three of the 60 satellites were abandoned in June 2019 after radio contact was lost.

In May 2019, Elon Musk announced that the Starlink network could go into minimal operation if the necessary infrastructure was set up on the ground and at least seven times 60 satellites had been successfully launched. Numerous other starts are necessary for full operation. In April 2020, he specified the start of operations as part of a beta phase for the summer of 2020 with a smaller group of users and another three months later with a larger group of users.

From the second expansion stage, the launches will take place with the new Starship and Super Heavy rocket instead of the Falcon 9. The Starship is expected to be able to transport 400 Starlink satellites into space with each flight.

Similar systems

In addition to SpaceX, OneWeb , Telesat and Amazon ( Kuiper project ) are also working on broadband internet constellations . OneWeb plans a network of 588 satellites, Telesat plans at least 292 satellites and Amazon 3236.

criticism

Starlink satellites a few hours after launch on May 24, 2019 over Pembrokeshire

Space junk

A major criticism of the systems is the possible creation and accumulation of space debris . The US supervisory authority Federal Communications Commission (FCC) wants to oblige satellite operators in future to bring satellites out of orbit at the end of their lifespan. The Starlink satellites should have enough fuel reserves to remove them from orbit at the end of their useful life - provided that there is no technical defect by then. In the case of around 9,000 satellites intended for low orbits, the atmospheric friction is enough to make them crash back to earth within five years after a control failure. Due to a low launch altitude (the target orbit is only reached after months with its own drive), satellites that have malfunctioned from the start burn up particularly quickly.

On February 20, 2020, Starlink-46 became the first satellite of the constellation to intentionally re-enter the Earth's atmosphere, followed by Starlink-1220 on March 9, 2020 and Tintin B on August 8, 2020.

Disturbance of the night sky and astronomy

Starlink above the town hall in Tübingen

Satellites a few hundred kilometers above sea level can be visible in the hours before dawn and after dusk . The first batch of 60 Starlink prototypes appeared surprisingly bright in the sky in the days after launch. Astronomers then expressed concern that large constellations such as Starlink could shape the image of the night sky and impair observations with optical telescopes . In addition, the radio signals used for data communication could interfere with radio astronomical observations. It is still unclear whether and to what extent such problems will actually occur. SpaceX is working with astronomy associations like the American Astronomical Society to minimize the potential impact. When Starlink L2 was launched in January 2020, one of the satellites (Starlink-1130 "Darksat") was given a darker surface for testing purposes, but this led to problems in the satellite's thermal management. When the Starlink L7 was launched, a satellite (Starlink-1436 "VISOR") was equipped with a sun visor to shield the sunlight and thereby reduce the brightness of the satellite in the night sky. From the ninth launch (August 2020), all new Starlink satellites should appear much darker. In addition, SpaceX would like to dispense with the originally planned orbits of the second expansion stage at an altitude of 1,100–1325 kilometers and to place all satellites below 600 km, which reduces their visibility at night and greatly reduces the dwell time of defective satellites.

Start list

As of August 31, 2020

Serial No. Date ( UTC ) rocket Launch site Number of satellites version Orbit approx. 1 Remarks
Test satellites
- February 22, 2018, 2:17 pm Falcon 9 VAFB 2 - approx. 520 × 500 km,
97.5 ° 		Tintin A and Tintin B
test satellites
- May 24, 2019, 2:30 am Falcon 9 CCAFS 60 v0.9 550 km, 53 ° Launch altitude 440 km; Prototype with limited functionality
First expansion stage (1584 satellites)
1 November 11, 2019, 2:56 pm Falcon 9 CCAFS 60 v1.0 550 km, 53 ° Launch altitude 280 km; First reuse of the payload fairing
2 January 7, 2020, 2:19 am Falcon 9 CCAFS 60 v1.0 550 km, 53 ° Launch altitude 290 km; one of the satellites was given a darker surface as a test in order to reduce the albedo .
3 January 29, 2020, 2:06 pm Falcon 9 CCAFS 60 v1.0 550 km, 53 ° Launch height 279 × 292 km; 3 track levels.
4th February 17, 2020, 4:05 pm Falcon 9 CCAFS 60 v1.0 550 km, 53 ° Launch height 213 × 386 km; 3 track levels.
5 March 18, 2020, 12:16 pm Falcon 9 KSC 60 v1.0 550 km, 53 ° Launch altitude 212 × 386 km; 3 track levels
6th April 22, 2020, 7:30 p.m. Falcon 9 KSC 60 v1.0 550 km, 53 ° Launch altitude 212 × 386 km; 3 track levels
7th June 4, 2020, 1:25 am Falcon 9 CCAFS 60 v1.0 550 km, 53 ° a "VisorSat"
8th June 13, 2020, 9:21 am Falcon 9 CCAFS 58 v1.0 550 km, 53 ° Secondary payload: SkySat 16, 17 and 18 from Planet Labs , first customer of the Smallsat Rideshare Program
9 August 7, 2020, 5:12 am Falcon 9 KSC 57 v1.0 550 km, 53 ° Launch height 388 × 401 km; Secondary payload: BlackSky Global 7 and 8. All Starlink satellites with sun visors
10 August 18, 2020, 2:31 pm Falcon 9 CCAFS 58 v1.0 550 km, 53 ° Launch height 210 × 390 km; Secondary payload: Skysat 19, 20 and 21
11 September 1, 2020, 1:29 pm Falcon 9 KSC 60 v1.0 550 km, 53 °
▲ started planned ▼
2020–2021
1–2 starts per month 		Falcon 9 Florida ≤ 60 ? 550 km, 53 ° possibly with secondary payloads as part of the Smallsat Rideshare Program
1Altitude and inclination of the target orbit of the satellites. From flight 1 onwards, they are released at a lower altitude and move into the target orbit on their own.

Web links

Commons : Starlink  - collection of images, videos and audio files

Individual evidence

  1. ↑ SpaceX seeks regulatory changes as it gears up for Starlink broadband service . Geekwire, April 28, 2020.
  2. ↑ Coco Huang: SpaceX Sets Record With Latest Launch. Los Angeles Business Journal, August 18, 2020, accessed August 24, 2020 .
  3. ↑ SpaceX successfully launches 60 more Starlink satellites but misses boosteer landing . TechCrunch, February 17, 2020.
  4. ↑ SpaceX's first batch of Starlink satellites already in Florida for launch debut. In: Teslarati. April 30, 2019, accessed April 30, 2019 .
  5. ↑ Caleb Henry: SpaceX submits paperwork for 30,000 more Starlink satellites. In: Spacenews. October 15, 2019, accessed October 15, 2019 .
  6. ↑ Eric Mack: SpaceX looks to rule space with 30,000 more satellites . cnet, October 15, 2019.
  7. ^ Application for Fixed Satellite Service by Space Exploration Holdings, LLC . SpaceX frequency request SAT-MOD-20200417-00037 dated April 17, 2020.
  8. ↑ a b Starlink: SpaceX tests internet satellites - Golem.de. Retrieved February 19, 2018 .
  9. ↑ Attachment Technical Information SAT-MOD-20181108-00083. Federal Communications Commission , November 8, 2018, accessed February 10, 2019 .
  10. ↑ Stephen Clark: SpaceX plans to launch “dozens” of Starlink test satellites this month. In: Spaceflight Now. May 7, 2019, accessed May 8, 2019 .
  11. ^ SpaceX: Application for Approval for Orbital Deployment and Operating Authority for the SpaceX NGSO Satellite System. Federal Communications Commission (FCC), November 15, 2016, p. 5 , accessed April 23, 2020 .
  12. ↑ a b c Caleb Hebry: Musk says Starlink “economically viable” with around 1,000 satellites. In: Spacenews. May 15, 2019, accessed May 16, 2019 .
  13. ↑ Chris Gebhardt: First Starlink mission to be heaviest payload launch by SpaceX to date . Nasaspaceflight.com, May 16, 2019; supplementary Twitter message , supplementary Twitter message .
  14. ↑ a b Starlink Mission press kit (Launch November 2019). In: spacex.com. SpaceX, January 9, 2020, accessed January 9, 2020 .
  15. ↑ Starlink Mission press kit (Launch May 2019). In: spacex.com. SpaceX, January 9, 2020, accessed January 9, 2020 .
  16. ↑ Liam Tung: Elon Musk's SpaceX: Now 1 million Starlink user terminals OKed for US internet service . ZDNet, March 24, 2020.
  17. ↑ Spacex: 60 Starlink satellites are ready to go. In: Golem.de. May 12, 2019, accessed on June 14, 2019 : "However, SpaceX had previously announced that the first 75 satellites would still be a version with limited functionality."
  18. ↑ Kenneth Chang: SpaceX Launches 60 Starlink Internet Satellites Into Orbit. In: nytimes.com . May 23, 2019, accessed June 18, 2019 .
  19. ^ Jackie Wattles: Here's what you need to know about SpaceX's Starlink internet service. In: CNN Business. Retrieved November 7, 2019 .
  20. ↑ Caleb Henry: SpaceX launches 60 Starlink satellites, begins constellation buildout. In: Spacenews. May 24, 2019, accessed May 24, 2019 .
  21. ↑ Space-Track.org , accessed September 6, 2019.
  22. ↑ Caleb Henry: Contact lost with three Starlink satellites, other 57 healthy. In: Spacenews. July 1, 2019, accessed July 1, 2019 .
  23. ↑ Twitter message from Elon Musk, May 12, 2019.
  24. ↑ Twitter message from Elon Musk, April 23, 2020.
  25. ↑ Twitter message from Elon Musk, December 23, 2018.
  26. ↑ Michael Sheetz: SpaceX wants to land Starship on the moon within three years, president says, with people soon after. October 27, 2019, accessed October 29, 2019 .
  27. ↑ OneWeb plans April launch break to tweak satellite design. In: Spacenews. February 6, 2020, accessed May 3, 2020 .
  28. ↑ Telesat says ideal LEO constellation is 292 satellites, but could be 512. In: Spacenews. September 11, 2018, accessed February 10, 2019 .
  29. ↑ Now also Amazon: With more than 3000 satellite internet for almost everyone. In: heise online. Retrieved April 6, 2019 .
  30. ↑ Space junk: "The new aspect are the mega-constellations". In: Golem.de. Retrieved February 19, 2018 .
  31. ↑ Starlink: SpaceX is allowed to launch over 7000 more satellites. In: WIRED. Accessed December 1, 2018 .
  32. ↑ SpaceX revises internet satellite launch plan to minimize space debris. In: engadget.com. September 11, 2018, accessed February 10, 2019 .
  33. ↑ SpaceX's Starlink satellites are clearly visible in the sky — and astronomers aren't happy. In: MIT Technology Review . May 28, 2019, accessed June 14, 2019 .
  34. ^ Korey Haynes: Global astronomy groups say they're concerned about SpaceX's Starlink. In: Astronomy.com. June 11, 2019, accessed June 13, 2019 .
  35. ↑ Starlink Mission press kit (3rd launch). In: spacex.com. SpaceX, January 6, 2020, accessed January 6, 2020 .
  36. ↑ Twitter message from Elon Musk, April 22, 2020
  37. ↑ Twitter message from Jonathan McDowell, April 11, 2020.
  38. ↑ Chris Gebhardt: Falcon 9 launches first Starlink mission - heaviest payload launch by SpaceX to date. In: Nasaspaceflight.com. May 24, 2019, accessed May 24, 2019 .
  39. ↑ Eric Ralph: SpaceX preps second $ 500M fundraiser as Starlink & Starship make progress. In: Teslarati. April 17, 2019, accessed June 18, 2019 .
  40. ↑ Frank Wunderlich-Pfeiffer: 60 Starlink satellites are ready to go. In: Golem.de . May 12, 2019, accessed June 18, 2019 .
  41. ^ Static fire test of Falcon 9 complete — targeting 11/11 for the launch of 60 Starlink satellites from Pad 40 in Florida. In: Twitter. SpaceX, November 5, 2019, accessed November 7, 2019 .
  42. ↑ The fairing supporting this mission previously flew on Falcon Heavy's Arabsat-6A missionpic.twitter.com/iTgqqtl1pW. In: Twitter. SpaceX, November 5, 2019, accessed November 7, 2019 .
  43. ↑ Watch live as Falcon 9 launches 60 Starlink satellites to orbit. In: Twitter. SpaceX, January 6, 2020, accessed January 7, 2020 .
  44. ↑ SpaceX launches first Starlink rideshare mission with Planet Labs. In: NASASpaceFlight.com. June 12, 2020, accessed June 13, 2020 (American English).
  45. ↑ Stephen Clark: Live coverage: SpaceX launches more Starlink satellites on Falcon 9 rocket - Spaceflight Now. Retrieved August 18, 2020 (American English).
  46. ↑ Smallsat Rideshare Program. SpaceX, accessed August 29, 2019 . SpaceX press release of August 29, 2019 via Twitter message from Chris Bergin, Nasaspaceflight.
  47. ↑ Caleb Henry: SpaceX plans 24 Starlink launches next year. In: Spacenews. September 10, 2019, accessed September 10, 2019 .
  48. ↑ SpaceX plans to start offering Starlink broadband services in 2020 . Spacenews, October 22, 2019.