SpaceX Defends Tests for Planned Satellite Constellation
SpaceX's experimental satellites to be tested next year in advance of the much larger low earth orbit (LEO) constellation it has planned for a global broadband service will turn off and on to avoid geostationary satellite signal interference, the company said in an Office of Engineering and Technology filing. The risks of those thousands of small satellites colliding with anything in orbit are microscopic, said the filing posted Monday.
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SpaceX plans to put up six to eight experimental satellites for test and demonstration purposes starting next year, with the satellites having a design operating lifespan of six to 12 months. The primary testing is to validate the design of a broadband antenna communications platform that will then let it set up its intended low-latency, worldwide, high-capacity Internet service. The broadband tests will be done in the X- and Ku-band with ground stations in Fremont and Hawthorne, California, and in Redmond, Washington.
The test plans faced objections from Intelsat, which earlier this month filed an informal objection to the experimental license needed. While SpaceX claimed in its application that any interference with other Ku-band services, such as Intelsat's, was unlikely, the lack of information in the license application makes it impossible to judge, Intelsat said. Specifically, SpaceX needs to provide such beam details as antenna numbers, beam width orientation and whether the beams will be on when they're outside the range of the receiving stations, as well as orbital parameters. "That SpaceX is required to operate on a non-protection, non-harmful interference basis is of little comfort to GSO operators if the source of the interference cannot be determined," Intelsat said. SpaceX also needs to make public more details about how its LEO satellites, in a 625 km-altitude orbit, won't interfere with providers of satellite launch and early-operation phase services such as itself, Intelsat said.
Intelsat's collision risk worries are "meritless" because the orbital relative orientation of its test satellites "results in the lowest and most negligible non-zero collision risk possible, with probabilities on an order of less than 1 in 1 quadrillion," SpaceX said. It also filed additional interference-related technical data in its response. To avoid interfering with GSO satellites or ground terminals, its MicroSat satellites will power down or cease downlinks in the Ku band or uplinks in the S band, SpaceX said. In a statement Thursday, Intelsat called it "helpful that SpaceX has provided additional technical information" and said it's "continuing to review their submission to determine if it is adequate for us to complete a thorough analysis of the potential impact."
The LEO broadband network world is in the midst of a boom. OneWeb announced last month plans to put up a 648 Ku-band satellite constellation that will tie into Intelsat's geosynchronous satellite network, creating a hybrid LEO/GSO broadband network (see 1506250023). LeoSat's LEO constellation is expected to launch in 2018 with 80 satellites, although the number might grow (see 1503040016).