The first key SpaceX innovation that makes Starlink possible is rocket re-use. Let’s take a look at why.
To make satellite internet responsive, the satellites need to fly much lower than traditional telecommunications/internet satellites which suffer from high latency. But if you fly in low earth orbit, rather than way up at geostationary orbit, your satellite moves across the sky rather quickly, and in a matter of minutes is on the other side of the planet totally out of view of your antenna. So one satellite, or even a few, isn’t enough. Flying in low earth orbit means you need hundreds, even thousands of satellites to ensure one is always overhead of every customer.
A significant chunk of the cost of satellites is the rocket launch to place the satellite in Earth orbit. Commercial rocket launches historically have cost anywhere from 100 million dollars to several hundred million dollars. The high cost of rocket launches is mostly due to their disposable nature. Traditional rockets are one-use beasts that, after their jobs are done, crash into the ocean never to be seen again.
SpaceX has created a partially re-usable rocket in the Falcon 9. Falcon 9 has two main parts or stages. The bottom, and much larger (and more expensive) part is the booster stage. The booster is a giant propellant tank and a bunch of rocket engines, nine in the case of Falcon 9. The booster is used to get the vehicle through most of the atmosphere where drag is a major force working against it. Once its job is done, the booster separates and falls back to Earth which lightens the load for the upper part or second stage to finish the job by achieving enough speed to reach orbit. Falcon 9’s second stage is much smaller and has only one engine. Once the second stage achieves orbit, it drops off the payload and falls back to Earth.
With the Falcon 9, the expensive first stage doesn’t burn up or crash into the ocean. Instead, it relights its engines and performs a propulsive landing and than can be re-used. The second stage, which is much less expensive does crash into the ocean.
To explain why saving the booster stage for re-use is so important to Starlink, let’s look at how SpaceX uses a rocket. Estimates are that it costs SpaceX about 30 million dollars to build a Falcon 9 rocket. 2/3ds of that cost is the booster and 1/3rd is the second stage. For a Falcon 9’s maiden voyage, SpaceX sells a launch to a commercial customer for say 60 million dollars making 30 million dollars in profit. That’s where a typical space launch provider would call it a day and start building its next rocket but not SpaceX. SpaceX lands that booster, refurbishes it, adds a new 10 million dollar second stage and flies it again for either another commercial customer, at a much higher profit margin, or uses it to launch its own Starlink satellites. And then they land the booster again, and can re-use it again, and again. The leading booster in SpaceX’s fleet has been launched 8 times.
So, SpaceX’s cost to launch a batch of Starlink satellites is probably about 1/6th the cost of its retail commercial launches, and 1/3rd the wholesale cost of a new rocket. By lowering this cost so much, SpaceX is able to launch an unprecedented number of satellites for far less than anyone else has been able to do before it. My rough math says that SpaceX was able to launch the first 1,000 Starlink satellites for about the same cost as a single satellite launch from a traditional satellite internet company.
When your plan is to launch 14,000 satellites, though, you need to find even more savings. And SpaceX is working on that. Their next rocket, called Starship, is fully re-usable. Both the first and the second stage return safely to Earth to be rapidly re-used. SpaceX wants rocket flights to be more like airline flights, where you fly, land, re-fuel, and fly again. By making the whole rocket re-usable, and by making it significantly larger and more powerful than the Falcon 9, SpaceX will be able to put the rest of the Starlink constellation up for an unheard of low cost.
Starship is in prototype stages, having made several low altitude flights but SpaceX hopes to achieve orbit with Starship very soon. Oh, and Starship is also the rocket that’s going to be first to put humans on Mars.