Starlink

Starlink is a constellation of satellites currently under construction by US private aerospace manufacturer SpaceX for low latency broadband global satellite internet access. The constellation will consist of thousands of miniaturized mass-produced satellites, placed in low earth orbit (LEO), which will work in tune with terrestrial transceivers. SpaceX also intends to commercialize some of its satellites for military, scientific and exploratory purposes.

Concerns have been raised about the long-term effects and damage of space debris resulting from the release of thousands of satellites in orbits above 1000 km. Later it was decided to use orbits around 550 km, which are relatively safer because they allow debris to decay in less time. Other criticisms are related to a possible negative impact in observational astronomy activities, which SpaceX has announced it will resolve. In June 2020, one of the constellation's satellites has an experimental coating specifically designed to make it less reflective and therefore less visible to astronomical observations from the ground.

The product development path began in 2015, with the first two test flights of the satellite prototypes launched in February 2018. The first launch for the deployment of part of the constellation took place on May 24, 2019 with the first 60 satellites. successfully brought into orbit. SpaceX's satellite development headquarters are in Redmond, Washington, where research, design, construction and operational control facilities reside.

The Starlink project plans to launch nearly 12,000 mini-satellites to offer a high-speed Internet service, which would be distinguished by its reduced latency from current satellite Internet offerings, based on large satellites placed in geostationary orbit. The latency time should be 25-35 ms, current technologies reach latencies of 600 ms. According to SpaceX, the project responds to a need dictated by the growth of new Internet uses such as online video games and video conferencing calls. But the project, which will lead to a tenfold increase in the current number of operational satellites in low orbit, is contested by other satellite operators, particularly because it could result in a significant increase in collision risk. The techniques used are already being implemented by the constellations Iridium and Globalstar (satellite phone), LeoSat (point-to-point connection) but above all by a project that has exactly the same objective as Starlink, OneWeb. The latter is based on a much smaller number of satellites (1000) and is in a more advanced state, with a date of entry into service scheduled for 2022.

The first massive launch of 60 satellites was carried out in May 2019 with a single Falcon 9 Block 5 rocket, which despite its total payload of 13,620 kg (excluding adapters and deployment mechanisms) should have sufficient propellants to allow landing. and the reuse of the first stage. These 60 satellites are part of a sub-series (block V0.9) of 75 prototypes that do not have an inter-satellite link system. They should define the remaining design aspects by verifying the in-orbit and disorbing procedures and operating procedures. They are part of the first phase of the deployment of the Starlink constellation, which involves 1,584 satellites to be placed in an orbit of 550 km with an orbital inclination of 53 °. The satellites in this orbital shell must be spread over 40 different orbital planes consisting of 66 satellites each. Deployment of the satellites in this phase will require the use of 24 Falcon 9 launchers. In order to provide minimal service, at least 360 satellites must be put into orbit.

The first two prototypes launched in February 2018 have dimensions of 1.1 × 0.7 × 0.7 m³ during launch and include two solar panels of 2 × 8 m² that are opened in orbit. The satellites launched in May 2019, which are still prototypes and do not have the inter-satellite connection for the operation of the Internet network, have a mass of 227 kilograms. The satellite has a very flattened shape, probably rectangular. The platform is equipped with Hall effect thrusters (motors that exploit the energy provided by solar panels) which produce their thrust by expelling krypton. These propellants are used to position the satellite, which is being lifted from an initial deployment orbit of 290 km to its operational orbit (550 km), to maintain the satellite's orientation during its operational life, and to lower the orbit at the end of its life to accelerate reentry into the atmosphere and not obstruct the low orbit. The payload includes four flat-phase phased array antennas for uplink and downlink. Operating satellites in the highest orbit transmit in the Ku band.