There's been a lot of controversy over the effect of SpaceX and Elon Musk's plans to move the internet into space. We take a look at what this really means.
You might have seen articles in the news recently about SpaceX's new Starlink constellation of satellites.
Planned to offer high speed, low latency, low cost internet worldwide, SpaceX's plans are undeniably ambitious. When complete, the network will consist of over 40,000 satellites. But the first two launches that have so far delivered 120 satellites to orbit have already raised concerns amongst astronomers.
Elon Musk is damaging the night sky. His satellites interfere with astronomers’ observations of stars and potentially harmful near-Earth asteroids, leaving streaks on images. No regulations require him to fix the problem. Soon it may be unfixable. https://t.co/RsxXoCbx3B pic.twitter.com/zpEobzjScp
— Jason Fagone (@jfagone) November 25, 2019
Images like these are concerning for astronomers, and this is after just two full launches. What will things be like when the full constellation of 40,000 satellites is on orbit?! And why do there need to there need to be 40,000 of them in the first place.
What is Starlink?
Starlink is a constellation of satellites orbiting the Earth that will, if all goes to plan, beam the internet down to users on Earth from space.
Space based internet is not a new idea, satellites have been used for communication since the 1960's. These communication satellites are typically located tin a geostationary orbit, which has advantages and disadvantages.
Since the satellite is in geostationary orbit, this means it always appears in the same place in the sky from Earth. This is great for simplicity of use, as the recieving antenna doesn't need to track the satelitte. It appears to be still! Being so high also allows it to see almost half of the Earth below it, allowing a single satellite to provide coverage to a large area.
Unfortunately a geostationary orbit is a long way above the Earth, meaning it isn't a quick journey for even light to make, and signals are weak by the time they are recieved. This limits the speed of traditional internet satellites to an average of around 1 Mb/s for downloads, 256 kB/s for uploads, and a latency of over 600 ms. This is slower than a traditional broadband connection, with a latency around 10x higher as well. These factors combined give limited use, and make them unsuitable for most uses, as well as being very costly.
SpaceX aim to avoid these problems by bringing their satellites a lot closer to the Earth. While geostationary satellites are over 35,000 km away, some of the Starlink constellation will be only 340 km above the Earth.
The benefits of this are that the problems with speed and latency suddenly disappear when you bring the satellites this close. Satelittes this close are far from still in the sky however. Individual Starlink's will be travelling at nearly 30,000 km/h and not very high up, meaning each one will only be able to see a small amount of the Earth for a short time as it zooms on by. This is why a lot of satellites are needed for a constellation like Starlink, as there always needs to be another satellite passing overhead to continue the connection! The recievers on Earth also need to be able to track the fast moving satellites, though this is able to be done by steering a beam rather than having to mechanically move the reciver dish.
What's good about Starlink?
1. It'll be fast
It's predicted that for long distance connections, like those between continents, Starlink will be faster than the undersea fibre optic cables that carry internet traffic world wide today.This is because signals are travelling at the speed of light, about 50% faster than it can travel through a fibre optic cable.
2. It'll be everywhere
Global access to high speed internet will be possible for the first time in rural, isolated and developing areas. At the moment around 1% of African people have access to broadband internet. With a Starlink antenna, high speed internet will be a click away, anywere on Earth.
3. It'll be cheap(?)
While pricing hasn't been announced yet, SpaceX and Musk have repeatedly stated that Starlink will be cheap and competetive. How cheap remains to be seen, but with the aim of providing internet access to developing communities, it's hoped to be affordable for everybody,
4. It's future ready!
So this is an article about SpaceX, and Mars hasn't been mentioned yet. SpaceX and Elon Musk have been talking about plans of humanity setting up base on Mars, and Starlink fits in to that plan nicely. A Mars based Starlink constellation is almost certainly in their plans for making Mars a home for humans.
What's bad about Starlink?
1. There's a lot of them
When complete, there will always be a Starlink satellite in view, almost anywhere in the world. That needs a lot of satellites, and that causes problems for astronomers. As the satellites travel around, they run the risk of getting in the way of objects astronomers are interested in looking at.
However each satellite is very small as seen from Earth, and they are distributed evenly around the globe, meaning the chances of an individual satellite passing through the small patch of sky a telescope is actually rather low.
2. They're bright (in many ways)
For a short time around sunrise and sunset, satellites in a low orbit are high enough that they are illumined while the ground below is still in darkness. This makes the satellite visible as it reflects sunlight down to Earth. With the large number of Starlink satellites, there will many individual satellites visible.
This is particularly evident shortly after launch as the 60 satellites haven't had a chance to spread out. This leads to what has become known as the "Starlink train", a line of satellites following each other closely in the sky.
These Starlink trains have caused concern amongst astronomers who have had the train pass overhead while taking measurements. With 60 reasonably bright satellites passing through the telescopes field of view, this makes astronomical observations worthless.
However it's worth noting that the train quickly disperses after launch as the satellites reach their operational orbit. The visibilty of the satellites also depends on the local time and whether or not the satellites are illuminated, which only occurs around sunrise and sunset, times not generally well suited to doing astronomical observations. To minimise these effects, the satellites can be painted to limit how reflective they are, and astronomers can check when a Starlink satellite will pass over head. Musk has taken to Twitter to confirm this is being investigated.
The satellites are also bright in other ways. While communicating with users on Earth using radio waves, the signals from the satellites may get in the way of astronomers studying the sky at these wavelengths. Unfortunately this cannot be solved with simple paint, and concerns have been raised about the future of radio astronomy in the future.
3. They could trap us on Earth
We can think of the constellation of Starlink satellites covering the Earth like a net. The "mesh" of the Starlink net is big enough that we can still easily launch into space through the holes in the net, but there are concerns that the mesh may not always be so wide.
With so many objects in orbit travelling at 30,000 km/h, if any collide the resulting crash would be catastrophic. Debris travelling faster than a rifle bullet will form a new net around the Earth with a tighter mesh, threatening to strike other satellites, generating yet more debris. Before long this runaway effect, called Kesler syndrome, could create such a tight net around the Earth it will be even trickier and more dangerous to launch into space than it is now.
There are already over 10,000 pieces of space junk in orbit, a number that is growing all the time. As we put more and more objects into space, the chances of a collision increase. While Starlink is capable of autonomous collision avoidance, it has to know what it is avoiding. If a small object that wasn't tracked came out of nowhere and struck a satellite, suddenly things get a lot more crowded in space.
Starlink: Good or Bad?
Starlink has the potential to connect people who would not otherwise have internet access. It promises high speed, low cost internet access to everyone, wherever they may be.
But this comes with costs and things that need careful consideration. From the effect on the night sky, both visibly and invisibly, to the risks of throwing a net around the Earth making it impossible to escape.
It is still early days in the fledgling industry of space based internet, and SpaceX aren't the only ones planning to offer this service. OneWeb, Amazon and Boeing to name just a few have their own plans, so at the moment it's looking like satellite constellations providing internet are here to stay.
Whether or not surrounding our planet with tens of thousands of satellites is a good thing remains to be seen. Constellations have the power to bring humanity together, but also trap it. The fears of the astronomy community are valid and it's only cooperation between parties that will determine the path forwards.
Afterall, the night sky belongs to all of us.