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Raumfahrt - SpaceX says more Starlink orbits will speed service, reduce launch needs

8.09.2019

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WASHINGTON — SpaceX is asking federal regulators to allow it to spread out satellites in more rings around the Earth, saying the tweak to its orbital plans could bring coverage to the southern United States in time for next year’s hurricane season. 

In a filing to the U.S. Federal Communications Commission, SpaceX said it wants to triple the number of orbital planes at 550 kilometers, the altitude where its lowest layer of Ku- and Ka-band Starlink satellites are to operate.

SpaceX launched its first 60 Starlink satellites May 23 on a Falcon 9 rocket. The company needs another six Starlink launches before it will have enough satellites to start partial service, but by splitting satellites into 72 rings instead of 24 as originally envisioned, Starlink will be more spread out, enabling greater launch efficiency, SpaceX said. 

“The proposed respacing would require fewer launches of satellites — perhaps as few as half — to initiate service to the entire contiguous United States,” SpaceX told the FCC Aug. 30. “Globally, the modification would enable more rapid coverage of all longitudes to grow toward the Equator, as well as bolstering capacity over in areas of greater population density.”

Along with the contiguous 48 U.S. states, SpaceX said the new orbits would also speed service to Hawaii, Puerto Rico, the U.S. Virgin Islands, the American Samoa, and the Northern Mariana Islands.

Most, but not all, Starlink satellites have used onboard electric propulsion to reach their operational 550-kilometer orbit. SpaceX is deorbiting at least five of the first 60 satellites — three that malfunctioned and two deliberately for test purposes. 

In its filing, SpaceX said it “expects to conduct several more Starlink launches before the end of 2019.”

SpaceX President and COO Gwynne Shotwell said in May that the company planned three to seven Starlink launches in 2019, depending on lessons learned from the first launch. 

SpaceX has since told the FCC it realized it can use a single launch to deploy Starlink satellites in three different orbital planes, rather than placing an entire batch in the same ring around the Earth. 

Spacing the satellites 22 to a ring instead of 66 per ring “accelerates the process of deploying satellites covering a wider service area,” SpaceX said. 

SpaceX said the adjustments to its plans could bring Starlink broadband service to southern U.S. states by the end of the 2020 hurricane season, and farther out territories by the 2021 hurricane season. 

Satellite communications companies regularly provide services after natural disasters, since storms and earthquakes can destroy cellular towers and terrestrial infrastructure, creating dark zones during times of crisis. Some are assisting the Bahamas in the aftermath of Hurricane Dorian, a category 5 storm that struck the Caribbean this past week. 

The International Telecommunication Union, a United Nations entity, said Sept. 6 it deployed a mix of 50 satellite phones from Iridium and broadband terminals from Inmarsat in the Bahamas in the aftermath of Hurricane Dorian. Spanish connectivity provider e3 Systems said Sept. 4 it is supporting a Yacht Aid Global vessel with satellite connectivity provided for free by Speedcast.

SpaceX has FCC approval to provide broadband services from a constellation of almost 12,000 satellites. In April, the commission approved SpaceX’s request to operate around 1,600 of those satellites at 550 kilometers instead of 1,150 kilometers as originally planned. 

SpaceX’s other authorizations allow for around 7,500 satellites between 335 and 346 kilometers, and around 2,800 satellites at altitudes between 1,110 and 1,325 kilometers. 

SpaceX said using 72 orbital planes for its satellites at 550 kilometers won’t cause a spike in signal interference, or orbital debris risk. The company said it is working with astronomers on making sure Starlink satellites don’t interfere with their research, and at this stage believes the change in orbital planes won’t “have any material impact on this ongoing analysis of reflectivity.”

Quelle: SN

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