This week SpaceX filed an update for its Federal Communications Commission (FCC) license to launch and operate an initial 1,600 Low Earth Orbit (LEO) communications satellites for its Starlink broadband service. The changes are designed to reduce the risk of space debris, RF interference, and enable faster deployment, plus a bonus on lower latency.
SpaceX proposes to launch 1,584 satellites to a lower altitude of 550 kilometers, down from an original altitude of 1,150 kilometers. Flying lower means any debris resulting from a satellite mishap will re-enter into the atmosphere more quickly, rather than lingering around and threatening other satellites. The satellites will be deployed in 24 orbital planes with 66 satellites per planes, down from an original 32 orbital planes with 50 satellites each.
Lower flying satellites also gain benefits in terms of RF interference. The SpaceX Starlink satellites will be able to use less power in operating data links between themselves and users on the ground, so there’s less risk of spilling over onto other authorized users of the RF spectrum. In addition, the initial satellites will only use Ku-band spectrum, with Ka-band rolled back into the design into future generations.
SpaceX says the modification to its license will enable it to accelerate the manufacture of its new spacecraft and get them into orbit faster, a significant factor that is driving Starlink. SpaceX CEO Elon Musk reportedly fired several Starlink managers over the summer because they were too conservative in their approach to getting production hardware into orbit. The new FCC filing supports SpaceX’s desire to more quickly build and deploy satellites.
Another bonus of lower flying satellites is lower latency for Starlink users. SpaceX’s pair of test satellites, Tintin A and B, have roughly 25 millisecond latency. In its filing, SpaceX expects to have 15 millisecond or so latency with the new satellites and 550 kilometer altitude orbit. Low latency is key if broadband satellite services are to compete with terrestrial fiber offerings, as Musk has often suggested Starlink could.
The updated filing comes as the FCC plans to publicly rule on SpaceX’s license request on November 15 to launch over 4,400 satellites using V-band spectrum for Starlink’s second-generation network.