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According to this answer, which cites Wikipedia, the current batch of Starlink satellites that are being deployed don't have the ability to talk to each other. That will come later, according to SpaceX.

My question: what, then, is the goal of launching these satellites? Without the ability to be part of a "mesh" network, it seems they are mostly useless, right? Are there other aspects of the satellites that are being tested? If so, which ones?

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Without the mesh network SpaceX cannot provide global service as originally assumed. A potential (but unsourced) model for what they have is similar to terrestrial mobile internet with ground stations in locations that have good internet access and provide service to a catchment area that reliably has satellites with line of sight to the ground station and the user. A random search got suggesting 2.93% of the US population without broadband access giving at least 9 million potential customers , plus an unknown number who have on paper access but their local provider is failing to deliver/overcharging. While the potential customers are global the current website (June 2020) suggests initial service to US and Canada.

Assuming the Starlink phased array antenna operates in a 45 degree cone that gives satellite footprint between 500 and 700 km, suggesting coverage of the US and Canada needs more than 10 ground stations but less than 100, very dependent on how often outages while satellites do not have both user and base station in sight are acceptable. With 22 satelites per plane and a 96 minute orbit period a new satelite will be along within a couple of minutes and for many uses occasional 5-10 seconds gaps would be acceptable. Not so useful for gaming of course.

The viability of this hybrid business model depends a lot on how effectively Starlink can find pockets of customers and negotiate the necessary terrestrial connectivity in various political entities and against other commercial interests.

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  • $\begingroup$ The link in the answer below suggests an 1800km diameter satellite footprint - does that change your numbers much? $\endgroup$ – Tim Jun 14 at 21:03
  • $\begingroup$ The article linked in Anthony's answer suggests that packets might be routed via multiple ground-to-space-to-ground hops, in which case most of the ground stations don't need terrestrial connectivity. $\endgroup$ – Harry Johnston Jun 14 at 21:52
  • $\begingroup$ @Tim that article is assuming a 25 degree minimum beam elevation. I've seen the 45 degrees in this answer quoted a number of times elsewhere as the minimum elevation Starlink will operate at (to avoid mutual interference with terrestrial users of the same spectrum). $\endgroup$ – Dan Is Fiddling By Firelight Jun 15 at 1:22
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http://www.circleid.com/posts/20191230_starlink_simulation_low_latency_without_intersatellite_laser_links/

This study claims that even without the inter satellite laser system, the latency is comparable to land fiber, which often take non-nominal paths. Light travels 31% more slowly in fiber compared to air.

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