SpaceX Starlink Group 3-3 Launch

SpaceX plans to launch 46 Starlink satellites into Shell 3, with an eventual 560 km circular service orbit at a near-polar 97.66° inclination, on 2022-08-12 at 21:40 UTC. The launch will be from Space Launch Complex 4 East at Vandenberg Space Force Base in California. The first stage booster, B1061, will be making its tenth flight, after a turnaround time of 54.71 days since its last mission. This booster previously launched, among other flights, two crew and one cargo mission to the International Space Station; this is its first flight from Vandenberg.

This is the third Starlink launch into Shell 3, intended to provide service to customers in high latitude locations. This shell is planned to eventually contain 348 satellites in six orbital planes of 58 satellites each. All satellites in Shell 3 are equipped with laser inter-satellite links. The reduced performance of Falcon 9 when launching to polar orbits limits the payload to 46 satellites compared to the 52 or 53 in launches to lower inclination orbits. Around ten launches are expected to fill Shell 3, which will complete coverage of high latitude areas and provide continuous service to Starlink-equipped aircraft on polar routes.

Here is the pre-flight preview from Everyday Astronaut.

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I haven’t seen much about the routes of the signal traffic on this network (and have no understanding of ISP networks, generally). I wonder how much of the connection to any one satellite is “uplink” to a ground station(s) - versus “downlink” versus “sidelink”, i.e. between satellites, before the downlink to the end user. I am guessing this LEO system involves lots of sophisticated handoff switching as satellites move beyond the horizon. There must be lots of sophisticated network engineering involved. Also, are these satellites all solar powered with batteries for those periods when they are in shadow?

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Here is a June 2021 article from Discover, “How Do SpaceX’s Starlink Satellites Actually Work?”, which describes the basics of operation. Since that article was published, SpaceX has moved to equipping all Starlink satellites with laser inter-satellite links which allows them to hand off data to adjacent satellites and reduce the number of ground stations and “back-haul” connections required to route packets to the terrestrial fibre backbone. This is particularly important for coverage of high latitude and polar regions, where it would be costly to install and maintain ground stations. All of the satellites launched into Shell 3 polar orbit have, from the start, been equipped with the laser links.

The satellites are solar powered and have batteries which allow them to operate while in the Earth’s shadow.

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Thank you , John.