Great post. One quick comment on the Geo satellites: while it may be true that three satellites is sufficient to get line of sight coverage to everywhere on earth, in practice it isn’t sufficient.
Beam scan loss on both the satellite payload and terminal side along with field of view geometry (that is a shallow angle of intercept may lead to poor feature definition in imagery) mean that communications and earth observation satellite constellations need to fly birds in orbits that specifically cover the poles to have full earth availability and coverage. This is why you see systems like AEHF, SBIRs high and others fly birds in Molniya (12 hour orbit with 10 hours hang over the pole) or increasingly popular Tundra (24 hour orbit) orbits to provide full coverage over at least the North Pole.
Go look up a “Walker constellation” for more on this. They actually aren’t SSO - that’s retrograde and meant for flying over same spot every day at the same time (popular with weather satellites). Lots of polar ones though.
You are the expert here Nathan! Totally makes sense, and in reality there are no 3-satellite GEO constellations right?
My overly-basic explanations of certain topics here were mostly meant to make this post approachable for non-space people--which I found to be super challenging!
Loved the article! One correction... the Tranche 0 satellites launching later with a partner to test a different orbit are L3Harris birds, not Raytheon ones.
Well there are 3 satellite Geo constellations, they just provide lousy service about 60 deg. In fact some providers have many satellites in Geo because their payloads have narrow FOV or they want more capacity.
Actually you’ll sometimes see 4 satellite GEO constellations with one held close as a spare in a particularly high throughput orbit in case the main money maker fails or it’s long in the tooth and they anticipate retiring it soon.
But I'm going to rain on the parade a little bit. Not because what you're saying is untrue, but because everything the SDA is buying still keeps the USSF in a support role. There's no protection of space assets there. And that's always been the case (no pun intended). Most of the missions you're seeing with the new stuff still falls in the realm of remote sensing, communications, etc., which are missions that the USAF and other have done for a while.
At the same time, at least the SDA is helping the USSF update its current mission sets, and that's exciting! Maybe that allows it some expansion once those new systems are in place? Although, the USSF needs policy changes to expand from support as well.
I look forward to seeing how the USSF's role evolves over time--there is certainly some jostling vs other DoD orgs as they get up to speed and expand the scope of their role beyond what USAF and others did in space historically
When I read "the speed that LEO satellites travel (10km/sec) make individual satellites more difficult targets vs stationary GEO satellites," and this is often cited elsewhere too, I wonder what is doing the targeting. Lasers to blind? Lasers to incapacitate? Lasers on the ground? Lasers in space? EM weapons? Objects in space (which would soon make LEO a full of debris days into a conflict?) Active objects blocking field of view (for managing escalation)? Naturally, did seeing someone readying or ready to disrupt GEO sats finally make the SDA plan take off? This implies a window we are trying to close.
Great post. One quick comment on the Geo satellites: while it may be true that three satellites is sufficient to get line of sight coverage to everywhere on earth, in practice it isn’t sufficient.
Beam scan loss on both the satellite payload and terminal side along with field of view geometry (that is a shallow angle of intercept may lead to poor feature definition in imagery) mean that communications and earth observation satellite constellations need to fly birds in orbits that specifically cover the poles to have full earth availability and coverage. This is why you see systems like AEHF, SBIRs high and others fly birds in Molniya (12 hour orbit with 10 hours hang over the pole) or increasingly popular Tundra (24 hour orbit) orbits to provide full coverage over at least the North Pole.
Okay it’s just clicking to me now why SpaceX also has a few satellites in SSO or polar orbits
Go look up a “Walker constellation” for more on this. They actually aren’t SSO - that’s retrograde and meant for flying over same spot every day at the same time (popular with weather satellites). Lots of polar ones though.
72 orbital planes in first shell- its a beast: https://www.frontiersin.org/articles/10.3389/frcmn.2021.643095
You are the expert here Nathan! Totally makes sense, and in reality there are no 3-satellite GEO constellations right?
My overly-basic explanations of certain topics here were mostly meant to make this post approachable for non-space people--which I found to be super challenging!
That launch chart for 2023 has a bigger wedge for the U.S.
2024 will be even more lopsided.
And if you adjusted the graph to instead count launches by mass? Oh boy...
BryceTech makes a chart like you are talking about for mass to orbit--they have to zoom in and exclude SpaceX to show details for everyone else!
Loved the article! One correction... the Tranche 0 satellites launching later with a partner to test a different orbit are L3Harris birds, not Raytheon ones.
correction made!
Well there are 3 satellite Geo constellations, they just provide lousy service about 60 deg. In fact some providers have many satellites in Geo because their payloads have narrow FOV or they want more capacity.
Actually you’ll sometimes see 4 satellite GEO constellations with one held close as a spare in a particularly high throughput orbit in case the main money maker fails or it’s long in the tooth and they anticipate retiring it soon.
Hey Case!
First--this is good stuff.
But I'm going to rain on the parade a little bit. Not because what you're saying is untrue, but because everything the SDA is buying still keeps the USSF in a support role. There's no protection of space assets there. And that's always been the case (no pun intended). Most of the missions you're seeing with the new stuff still falls in the realm of remote sensing, communications, etc., which are missions that the USAF and other have done for a while.
At the same time, at least the SDA is helping the USSF update its current mission sets, and that's exciting! Maybe that allows it some expansion once those new systems are in place? Although, the USSF needs policy changes to expand from support as well.
Very good point, John
I look forward to seeing how the USSF's role evolves over time--there is certainly some jostling vs other DoD orgs as they get up to speed and expand the scope of their role beyond what USAF and others did in space historically
When I read "the speed that LEO satellites travel (10km/sec) make individual satellites more difficult targets vs stationary GEO satellites," and this is often cited elsewhere too, I wonder what is doing the targeting. Lasers to blind? Lasers to incapacitate? Lasers on the ground? Lasers in space? EM weapons? Objects in space (which would soon make LEO a full of debris days into a conflict?) Active objects blocking field of view (for managing escalation)? Naturally, did seeing someone readying or ready to disrupt GEO sats finally make the SDA plan take off? This implies a window we are trying to close.