SpaceX, the world’s leading private company in space technology, shot 60 satellites into orbit last week, and will keep doing so until it has a 12,000-strong constellation in place. In two years, it hopes to supply non-stop, low-cost Internet everywhere on Earth.
The Starlink network, as the project is called, is one of several ongoing efforts to start beaming data signals from space, and also the most ambitious.
Satellites-Internet services connection
- To provide universal services: This is mainly to ensure that reliable and uninterrupted Internet services, a basic infrastructure and an important means of delivering a wide variety of public services to the world’s peoples, are universally available in every part of the globe.
- To improve accessibility: Currently, about 4 billion people, more than half the world’s population, do not have access to reliable Internet networks. And that is because the traditional ways to deliver the Internet cannot take it everywhere on Earth.
Signals from satellites in space can overcome this obstacle easily.
Idea of space Internet
- Space-based Internet systems have, in fact, been in use for several years now but only for a small number of users. Also, most of the existing systems use satellites in geostationary orbit.
- Satellites in this orbit move at speeds of about 11,000 km per hour, and complete one revolution of the Earth in the same time that the earth rotates once on its axis.
- To the observer on the ground, therefore, a satellite in geostationary orbit appears stationary.
Placing satellites in lower orbits
Advantages of geostationary satellites
- One big advantage of beaming signals from geostationary orbit is that the satellite can cover a very large part of the Earth.
- Signals from one satellite can cover roughly a third of the planet and three to four satellites would be enough to cover the entire Earth. Also, because they appear to be stationary, it is easier to link to them.
Issue of latency: The Internet is all about transmission of data in (nearly) real time. However, there is a time lag called latency between a user seeking data, and the server sending that data.
And because data transfers cannot happen faster than the speed of light, the longer the distance that needs to be covered the greater is the time lag, or latency.
Advantages of space-based networks
- In space-based networks – Here the data requests travel from the user to the satellite, and are then directed to data centers on the ground. The results then make the same journey in the reverse direction.
- Faster transmission: A transmission from a satellite in geostationary orbit has a latency of about 600 milliseconds.
- A satellite in the lower orbit, 200-2,000 km from the Earth’s surface, can bring the lag down to 20-30 milliseconds, roughly the time it takes for terrestrial systems to transfer data.
- The LEO extends up to 2,000 km above the Earth’s surface. The Starlink satellites will be deployed in the altitude band of 350 km to 1,200 km.
Problems associated with lower orbit
- More satellites are needed: Owing to their lower height, their signals cover a relatively small area. As a result, many more satellites are needed in order to reach signals to every part of the planet.
Typically, they go around the Earth once every few hours. To compensate for the fact that they cannot be seen from a terrestrial location for more than a few minutes, many more satellites are needed in the networks.
That is the reason why the Starlink network is talking about 42,000 satellites.
- Downside to this project: Three issues have been flagged —
- increased space debris
- increased risk of collisions and
- the concern of astronomers that these constellations of space Internet satellites will make it difficult to observe other space objects, and to detect their signals.
- To put things in perspective, there are fewer than 2,000 operational satellites at present, and fewer than 9,000 satellites have been launched into space since the beginning of the Space Age in 1957. Most of the operational satellites are located in the lower orbits.
- On September 2 this year, the European Space Agency (ESA) had to perform, for the first time ever, a “collision avoidance manoeuvre” to protect one of its live satellites from colliding with a “mega constellation”.
- Increased light pollution: Astronomers and scientists have also complained about increased “light-pollution”, a reference to light reflected from the man-made satellites that can interfere with and be mistaken for light coming from other heavenly bodies.
Once operational, space-based Internet networks are expected to change the face of the Internet. Services such as autonomous car driving are expected to be revolutionized, and the Internet of Things (IoT) can be integrated into virtually every household, whether urban or rural