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SpaceX cuts broadband satellite height in half, to prevent debris


Illustration of the Earth, with lines circling around the globe to represent the telecommunications network.

SpaceX has received approval from the Federal Communications Commission to halve the orbital altitude of more than 1,500 planned broadband satellite in order to reduce the risk of space debris and improve retention.

SpaceX satellite project, called Starlink, is committed to providing high-speed, low-latency broadband worldwide. In a statement about the new approval of FCC, SpaceX says that "Starlink production is in full swing and the first satellites of the group has already arrived at the launch pad for processing."

SpaceX last year received FCC approval for the launch of 4,425 low-Earth orbit satellites at several different altitudes from 1,110km to 1,325km. However, FCC approval was contingent on the SpaceX supply more detailed plan for reducing clogging.

As part of its plan for the prevention of space debris, SpaceX later asked for permission to run these 1,584 satellites at an altitude of 550 km instead of the previously approved 1,150km. FCC approved the request in an order on Friday, but noted that SpaceX is still to provide a detailed plan to reduce the clogging of the remaining satellites.

"Taking into account the resistance of the atmosphere at this lower altitude, it is moving considerably improve the safety of space, ensuring that any orbital debris will be quickly re-enter and death in the atmosphere," said SpaceX FCC in November 2018 years in his statement to the modification of the license.

At a lower altitude, "any orbital debris will be subject to rapid atmospheric re-entry and death, even in the unlikely event when the spacecraft fails in orbit.» (SpaceX develops its satellites to completely burned during the return in the atmosphere in order to prevent physical damage caused by falling objects.)

Satellites in orbit 1,150 kilometers will be "hundreds of years to enter the Earth's atmosphere," but SpaceX "satellite will take at least five years (even in the worst case assumptions) if it begins at an altitude of 550 km," the company said.

The lower height will bring the advantage of broadband users, said SpaceX. "By working closer to the Earth, SpaceX also reduce the waiting time of their communication signals as low as 15 milliseconds, and at this point it would be virtually imperceptible to most users," the company said. (SpaceX said latency from a height of up to 1,150km will be 25ms 35ms.)

Low-altitude compromise

There are disadvantages of using a lower altitude, though.

"The very same resistance to the atmosphere, allowing sweeping orbit cleaning of debris, also makes satellites to work harder to remain in orbit," wrote SpaceX. "Stay in the air requires the satellite to be able to overcome more atmospheric resistance. In addition, satellites, working at low altitude cm smaller than Earth, requiring a larger number of satellites to serve this area. "

SpaceX said it conducted tests which show that it can solve these problems. SpaceX said that he intends "to work at this level, however, partly based on feedback received from its satellites, which have conducted extensive tests SpaceX opportunities to work in the lower range of 500 km. Thus, SpaceX learned to mitigate the disadvantages of operating at a low height and are still reaping the well-known and significant benefits. "

SpaceX plans to reduce the number of satellites in low Earth orbit Suzorye & # 39; and from 4,425 to 4,409. Planned orbital height of the remaining 4,409 satellites have not been changed. In accordance with its FCC authorization, SpaceX has to start at least half of these satellites on March 29, 2024, and the other on March 29, 2027.

FCC said he was satisfied with the plan to mitigate debris SpaceX in 1584 for satellites that are subject to change height. But SpaceX must submit a detailed plan for the remaining satellites.

"While we see that the orbital debris mitigation plan is sufficient for the space station, SpaceX The applicant proposes to work under its modifications, SpaceX has not provided any new information on orbital debris mitigation plans for other satellites in the proposed system» FCC said. «SpaceX has only partially satisfied with the conditions of its authorization, which requires SpaceX present, and approved by the Commission, an updated plan for the orbital debris mitigation prior to the service."

The new height of 550 kilometers is not the lowest, that SpaceX plans to use for its broadband services. SpaceX has received a separate permit in November 2018 to deploy the 7518 broadband satellites at altitudes of 335km to 346km. These lower satellites are designed to increase capacity and reduce delays in densely populated areas. In general, SpaceX has FCC approval to launch about 12 thousand broadband satellites.

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