With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

SpaceX said its planned constellation of 4,425 broadband satellites will launch from the Falcon 9 rocket beginning in 2019 and continue launching in phases until reaching full capacity in 2024. SpaceX gave the Senate Commerce Committee an update on its satellite plans during a broadband infrastructure hearing.
. Satellite Internet access traditionally suffers from high latency, relatively slow speeds, and strict data caps. But as we reported in November, SpaceX says it intends to solve these problems with custom-designed satellites launched into low-Earth orbits.
SpaceX mentioned 2019 as a possible launch date in an application filed with the Federal Communications Commission in November and offered a more specific launch timeline today. Cooper told senators:
Later this year, SpaceX will begin the process of testing the satellites themselves, launching one prototype before the end of the year and another during the early months of 2018. Following successful demonstration of the technology, SpaceX intends to begin the operational satellite launch campaign in 2019.
The remaining satellites in the constellation will be launched in phases through 2024, when the system will reach full capacity with the Ka- and Ku-Band satellites. SpaceX intends to launch the system onboard our Falcon 9 rocket, leveraging significant launch cost savings afforded by the first stage reusability now demonstrated with the vehicle.
The 4,425 satellites will "operat[e] in 83 orbital planes (at altitudes ranging from 1,110km to 1,325km)," and "require associated ground control facilities, gateway Earth stations, and end-user Earth stations," Cooper said. By contrast, the existing HughesNet satellite network has an altitude of about 35,400km, making for a much longer round-trip time than ground-based networks.
SpaceX has also proposed an additional 7,500 satellites operating even closer to the ground, saying that this will boost capacity and reduce latency in heavily populated areas. But Cooper offered no specific timeline for this part of the project.