This post’s subject is SpaceX’s ambitious Starlink project. It promises to bring broadband high-speed internet everywhere on the planet.
The current problem of satellite communications
The current communication satellites which provide internet service, are in Earth’s geostationary orbit, at 35,786 km (22,236 mi) of altitude. This long distance causes high latency, delay of the signal’s arrival.
The Starlink constellation
Starlink will be a constellation of 12,000 satellites, in the future can increase to 40,000. It was announced in January 2015, however the first satellites Tintin A and Tintin B were launched in 2018. SpaceX hasn’t developed yet a low-cost router that can be installed by the consumer, that is the main reason for delay.
In May 2018, SpaceX received authorization from FCC (Federal Communications Commission) to launch 4425 satellites in Low Earth Orbit (LEO), from 550 km (341 mi) to 1325 km (823 mi). In November the same year obtained authorization to launch more 7518 in Very Low Earth Orbit (VLEO), between 335 km (208 mi) and 346 km (214 mi).
SpaceX’s Falcon 9 can launch 60 Starlink satellites.
When lower the altitude, lower latency and area coverage, because of that will be a megaconstellation. The satellites will be transceivers (transmitters and receivers), which will transmit and receive signals from Earth and transfer information to other satellites in modulated lasers.
Starlink satellite
Each Starlink satellite weighs 227 kg (550 lb). It’s equipped with 4 phased array antennas for communication with Earth and 5 lasers to transfer information to other satellites.
To automatically enters the operational orbit and avoid collisions, are used ion thrusters with krypton gas. The operation of ion propulsion and noble gas involved will be for another post. When it ends its lifespan, these thrusters will take the satellite out of orbit and will reenter in the atmosphere. Keeping it from becoming space junk.
Why not use optical fibers?
The speed of light in vacuum (c) is 299.792.458 m/s. While in glass, material that composes the core of optical fibers, is much slower. Because the refraction index n is approximately 1.47. There is a small variation of this value, depending on the type of optical fiber. Calculating the speed of light in this material.
v=\frac{c}{n}
v=\frac{299792458}{1,47}=203.940.447,6 m/s
Therefore, Starlink’s internet will have lower latency. In addition to dismissing the need for long cables, reducing costs.
Answering some questions
According to site BroadbandNow, there is no prediction when Starlink will be available for the public and there is no information about price. It is improbable that provides cellular service. Theoretically, speed internet will be 1000 Mbps (Megabits per second).
Controversies and military applications of Starlink
Although Starlink promises to bring fast and cheap internet, not everybody is hyped with the project. Some claim that Starlink will harm astronomical observations, including compromise the capacity to detect asteroids that can hit Earth. Radioastronomy also can be harmed by satellites’ interference.
In addition to the excessive quantity of satellites, which can make future space missions unviable. But SpaceX claimed that it will work with organizations and space agencies to mitigate this problem.
On April 8 this year, SpaceX and the US military made a live fire exercise. Where Starlink satellites were connected with many weapon systems for communication and coordination.
The exercise involved in shooting down a drone and a cruise missile. Was made to test AMBS, a new communication system to coordinate military actions, and will help to replace the fleet of E8-C Joint STARS.
