SpaceX says it plans to change its satellite launch strategy in a way that will speed up deployment of its Starlink broadband service and has set a new goal of providing broadband in the Southern United States late next year.
In a filing on August 30, SpaceX asked the Federal Communications Commission for permission to “adjust the orbital spacing of its satellites.” With this change, each SpaceX launch would deploy satellites in “three different orbital planes” instead of just one, “accelerating the process of deploying satellites covering a wider service area.”
“This adjustment will accelerate coverage to southern states and US territories, potentially expediting coverage to the southern continental United States by the end of the next hurricane season and reaching other US territories by the following hurricane season,” SpaceX told the FCC. The Atlantic and Pacific hurricane seasons each begin in the spring and run to November 30 each year.
SpaceX said it already planned to “provide continual coverage over northern states after as few as six more launches,” but said it needs a license modification to speed up deployment in the Southern US. SpaceX’s filing stresses the importance of quickly getting service to parts of the US where broadband coverage is limited.
“With this straightforward adjustment, SpaceX can broaden its geographic coverage in the early stages of the constellation’s deployment and enable service initiation to serve customers earlier in the middle latitudes and southern-most states, and critically, those often underserved Americans in Hawaii, Puerto Rico, and the US Virgin Islands,” the company told the FCC.
SpaceX has been somewhat vague about launch dates for its broadband service. In October 2017, SpaceX told a Congressional committee that it would launch at least 800 satellites before offering commercial service and said the commercial service would likely become available in 2020 or 2021, as SpaceNews reported at the time. Last year, Reuters reported that SpaceX’s goal of a 2020 launch was “pretty much on target.” SpaceX CEO Elon Musk had fired some of Starlink’s senior managers in order to stay on schedule.
In its new FCC application, SpaceX said the adjustment in orbital spacing means it would need “fewer launches of satellites—perhaps as few as half—to initiate service to the entire contiguous United States (as well as Hawaii, Puerto Rico, the US Virgin Islands, American Samoa, and the Northern Mariana Islands).” In the rest of the world, “the modification would enable more rapid coverage of all longitudes to grow toward the Equator, as well as bolstering capacity in areas of greater population density,” SpaceX said.
Unlike traditional satellite broadband, SpaceX’s low-Earth orbit satellites would be able to provide latency as low as 25ms and gigabit speeds. In order to cover any given region, SpaceX said it must “deploy a sufficient number of nodes to ensure continuous coverage,” and “have enough antennas in the right physical configurations to hand off signals.”
No change to altitude or inclination
The orbital-spacing adjustment will not change “the overall number of satellites, their altitude or inclination, their operational characteristics, or their orbital debris implications,” SpaceX said.
If the change is approved, SpaceX satellites would travel in 72 orbital planes instead of the previously approved 24, and there would be 22 satellites in each plane instead of the previously approved 66 in each. This would affect 1,584 out of the 11,943 satellites that SpaceX has FCC authorization to launch. The altitude and inclination would remain unchanged at 550km and 53°, respectively.
An orbital plane is defined by two parameters: the orbiting object’s inclination, and the longitude of its ascending node. I wasn’t sure how to describe this in layman’s terms, so I consulted with our science editor, John Timmer. He explained it this way:
Imagine a spacecraft that orbits so that it’s constantly over the equator. The plane defined by that orbit would cut the earth in half, separating the Northern and Southern Hemisphere. But it’s relatively easy to tilt that plane, so a spacecraft would loop into the northern latitudes for half of its orbit, and into the southern for the other half. By putting a set of spacecraft in enough of these planes, SpaceX plans to greatly expand the areas that can be served by its fleet of satellites.
SpaceX launched 60 satellites in May this year to test the system before preparing for a wider deployment. SpaceX said its “iterative process” led to its new proposal.
“SpaceX has demonstrated the effectiveness of its revolutionary deployment process and confirmed its ability to populate three orbital planes with a single launch,” the company said in its new filing. “By then reorganizing its satellites at their already authorized altitude, SpaceX can place coverage and capacity more evenly and rapidly across more of the US.”
SpaceX also said it plans “to conduct several more Starlink launches before the end of 2019,” and asked the FCC to rule on its application quickly.
The European Space Agency (ESA) this month had to take action to avoid a collision with a SpaceX broadband satellite because a bug in SpaceX’s on-call paging system prevented the company from getting a crucial update about an increased collision risk. But SpaceX said in its FCC filing that the overall collision risk is still near zero “because SpaceX has invested in propulsion for its satellites.”