Third batch of Starlink satellites
SpaceX launched its third batch of 60 mini-satellites into orbit, part of its plans to build a giant constellation of thousands of spacecraft that will form a global broadband internet system. A live broadcast by SpaceX showed a Falcon 9 rocket taking off without incident from Cape Canaveral, Florida on 7 January 2020. The satellites are set to release about one hour after takeoff, bringing the total number of satellites that are part of the US company’s Starlink network to just under 180. But that figure could one day total 42,000, resulting in far more crowded skies, which has raised concerns among astronomers that they may one day threaten our view of the cosmos.
- To put that into context, there are currently around 2,100 active satellites orbiting our planet, according to the Satellite Industry Association. The launch was broadcast live by SpaceX, a company created by tycoon Elon Musk, who is also chief executive of Tesla.
- SpaceX’s goal is to control a huge share of the future internet market from space. Several rivals have the same ambition, including London-based startup OneWeb and giant US retailer Amazon, whose Project Kuiper is far less advanced.
- Musk hopes eventually to control three to five percent of the global internet market — a share valued at $30 billion a year, or 10 times what SpaceX is earning from its space launches, and plough the profits back into rocket and spaceship development.
- SpaceX’s boss also entertains a long-time dream of colonizing Mars. His California-based company has so far received US authorization to launch 12,000 satellites in several different orbits, and it has applied to launch as many as 30,000 more. SpaceX says its satellite constellation will be operational for Canada and the northern US by next year.
- Astronomers say the proliferation of the bright metallic satellites could seriously degrade the night view, interfering with both optical and radio astronomy.
- But SpaceX argues it has taken steps to reduce the satellites’ reflectivity and is testing an experimental darkening treatment on one of the satellites. Laura Forczyk, a space analyst, said the measures’ effectiveness was still uncertain.
- SpaceX has not yet eased the minds of astronomers concerned about the reflectivity of their Starlink satellites. The real test will be the days following launch when the smallsats are close together and in a lower altitude before ascending to their final orbit.
- Astronomers and stargazers will be able to compare the brightness of this current batch of smallsats compared to previous versions.
- Another criticism of more crowded skies is it will result in expensive collisions between satellites, potentially creating thousands of pieces of new space junk.
- SpaceX says it has a plan for that, too: its Starlink satellites deploy at an altitude of 290 kilometers (180 miles) and then engage their ion thrusters to reach an orbit of 550 kilometers (340 miles).
- At the end of their life-cycles, the satellites will use their propulsion systems to de-orbit over the course of a few months — or if these fail, they will burn up naturally in the atmosphere in under five years, compared to the thousands of years required at higher altitudes.
Why is it necessary to launch satellites in order to provide Internet services?
- This is mainly to ensure that reliable and uninterrupted Internet services — now part of humanity’s 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.
- Currently, about 4 billion people, more than half the world’s population, do not have access to reliable Internet networks.
- This is because the traditional ways to deliver the Internet — fibre-optic cables or wireless networks — cannot take it everywhere on Earth.
- In many remote areas, or places with difficult terrain, it is not feasible or viable to set up cables or mobile towers. Signals from satellites in space can overcome this obstacle easily.
How old is this 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. Most of the existing systems use satellites in geostationary orbit.
- This orbit is located at a height of 35,786 km over the Earth’s surface, directly above the Equator.
- 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.
So how will placing satellites in lower orbits help?
- 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.
- But satellites in geostationary orbit also have a major disadvantage. 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 (in reality, they take place at significantly lower speeds), the longer the distance that needs to be covered the greater is the time lag, or latency.
- In space-based networks, data requests travel from the user to the satellite, and are then directed to data centres on the ground.
- The results then make the same journey in the reverse direction. A transmission like this 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 — the 12,000 for which SpaceX has permission, as well as the other 30,000 that it wants to launch — will be deployed in the altitude band of 350 km to 1,200 km.
- The first batch of Starlink satellites — also numbering 60 and similar in configuration to the ones launched on November 11— went up on May 24, but they will not be part of the network.
- SpaceX announced the satellite Internet constellation in January 2015, and launched two test satellites in February 2018. Following launch, the company has now deployed 122 satellites in orbit.
- In October, SpaceX appeared ready to scale up its ambition, telling the International Telecommunication Union (ITU) in filings through the United States Federal Communications Commission (FCC) that it intends to deploy another 30,000 Starlink satellites in Low Earth Orbit (LEO) in coming years.
- The ITU is the United Nations specialised agency for information and communication technologies, with a membership of 193 member states, some 900 companies, universities, and international and regional organisations. The FCC is the statutory communications regulator of the US.