[domh]

This is wild. I had no idea of the scope of Starlink satellites in orbit. What is the life cycle of one of these satellites? How long do they last in orbit? Can they be controlled where they crash land down? How many different versions of the satellites are in orbit? I wonder how often they have their software updated and what happens in the failure state of an unsuccessful update?

[bryanlarsen]

They have a lifespan of about 5 years, the limit is the amount of maneuvering propellant to compensate for atmospheric drag they have on board. Next gen, which will be launched by the much larger Starship, may have a lot more propellant.

Most are in a five year orbit. This means that if SpaceX loses control of the satellite it will deorbit in five years due to atmospheric drag. Under control they deorbit within hours. They plan on switching to a one year orbit in the future.

They have purposefully deorbitted hundreds of satellites. They had a couple of early satellites deorbit naturally without control, but all starlinks currently orbiting are under control.

Starlinks are designed to burn up in atmosphere. On deorbit they do not reach the Earth.

I imagine Starlinks are like other Musk products and get updates multiple times per month, but that's a guess.

[mlindner]

Hey bryanlarsen, as a request could you not post things like this that are confidently incorrect?

> They had a couple of early satellites deorbit naturally without control, but all starlinks currently orbiting are under control.

A trivial check at any online database would find that there are many not under control. And satellites also still deorbit naturally without control pretty regularly.

[hi41]

Since the satellites are in zero gravity will they continue to be in orbit forever?

Or do satellites need some power to continue to stay in orbit?

If satellites can deorbit without power what forces would cause that?

[BenjiWiebe]

There's wisps of atmosphere where they are. The drag causes them to slow down, which lowers their orbit. Then they hit thicker air and get more drag and go lower yet. And then they get so hot from all the friction the cook to bits.

Oversimplified.

[bryanlarsen]

Yup. There's not much atmosphere way up there, but if you hit it at 17,000 miles per hour even a little bit can be significant!

[typon]

If they send them farther out does that increase their lifespan due to thinner atmosphere? Why target 1 year instead of five year?

[bryanlarsen]

Yes, higher orbits would have increased lifespan, a little bit longer for satellites under control and likely decades longer for satellites out of control.

I think the primary motivation for lower orbits would be compatibility with cellular telephones. While they have gotten it to work at current altitudes, it must be a lot easier at lower ones.

Other reasons could be decreased latency, less overlap/interference between coverage areas, reduced chance of Kessler syndrome, decreased power usage for transmission & reception.

[aednichols]

Having them as low as possible improves latency, which is a big selling point of Starlink over incumbent geostationary services like Hughesnet.

[domh]

Thank you! This is very interesting to read. I'll have to do some more research myself.