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SpaceX Applies for a Constellation Re-Design and Announces Beta Test Dates

This week SpaceX petitioned the FCC to reconfigure their Starlink constellation [PDF download, FCC.gov] and Elon Musk outlined their beta testing plan. As shown below, the most significant configuration change is reducing the altitude of four of the five groups of orbital planes by around 50%.

Table 1. Summary of Currently Authorized NGSO Constellation
SpaceX Current Authorization
Orbital Planes7232856
Satellites per plane2250507575
Altitude550 km1,110 km1,130 km1,275 km1,325 km
Inclination53°53.8°74°81°70°

Table 2. Summary of Proposed Modification
SpaceX Proposed Modification
Orbital Planes72723664
Satellites per plane2222205843
Altitude550 km540 km570 km560 km560 km
Inclination53°53.2°70°97.6°97.6°

The total number of satellites and the number orbiting at a 53-degree inclination, which gives good coverage over relatively affluent regions, are not changed very much. In their application, SpaceX points out that the other inclination revisions would favor coverage in the more northern and southern regions and the lower altitudes will reduce satellite-ground latency and facilitate the de-orbiting of defective and obsolete satellites, reducing the risk of collision.

When and why did they decide to request this change? I've seen a lot of speculation online. Was OneWeb's bankruptcy which opened the Alaskan market, they had planned to cover this year, a factor? How about difficulty with developing inter-satellite laser links, making satellite-ground latency a priority? Negative feedback from some potential market segments or nations? Antenna design difficulty? Capacity constraints? Launch cost? Difficulty dealing with the risk of debris? Capital constraints? Etc. Etc. Were they pursuing multiple designs in parallel from the start? No one outside of SpaceX knows why and when they made the decision to change, but regardless of the reason and timing, a major change this late does not inspire confidence and this is their second major revision.

Well, enough speculation. No one outside of SpaceX knows what went into the decision, so let's turn to Elon Musks tweet announcing beta test plans:

The first beta will probably be restricted to SpaceX insiders and carefully controlled and monitored, but what about the second, public tests? I have a house in a small mountain community with no landline Internet service and would love to be included, but Musk's tweet says they will "starting at high latitudes," and my house is at around 34 degrees. At the current launch rate of 60 per month, around 720 53-degree inclination satellites will have been launched by the start of the public beta tests. My house will have coverage at that point so if Elon wants some beta testers in the southern portion of the coverage sweet spot, I'll volunteer.

Oh, by the way, SpaceX launched 60 Starlink satellites today and landed the used booster on a barge at sea. Cool, but getting to be routine — not particularly newsworthy.

By Larry Press, Professor of Information Systems at California State University – He has been on the faculties of the University of Lund, Sweden and the University of Southern California, and worked for IBM and the System Development Corporation. Larry maintains a blog on Internet applications and implications at cis471.blogspot.com and follows Cuban Internet development at laredcubana.blogspot.com. Visit Page

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