When Mike Griffin started the Space Development Agency under Trump in 2019, he said we need LEO constellations to track hypersonic missiles and be proliferated to be robust against anti-satellite tech.
However, existing MEO satellites have proven capable of tracking hypersonics just fine. Meanwhile LEO satellites are way more vulnerable to ASAT, they can be directly hit. No... LEO only makes sense when you look at Mike Griffin's history working on the Strategic Defense Initiative. He sees LEO constellations of sensors as the first step to including space-based kinetic interceptors (hypersonic reentry vehicles, aka space weapons) which need to be close to Earth in LEO to work. He is part of the hawks in Washington trying to build a space-based power projection system for boost-phase interception and prompt global strike.
Not invalidating the rest of your chain of reasoning, since I agree with the idea this is likely to lead to eventual space based mid course interception….
While MEO satellites are able to do the job, they pose a greater “systemic risk” than LEO satellites do.
If a war goes hot with long range use of prompt global strike style hypersonic weapons against the USA or its closely allied military alliance partners like UK, Japan, Australia, Canada, etc… we’re talking about a scenario where the potential adversaries are going to be precipitously close to the use of anti satellite weapons, and potentially even nukes but let’s ignore them and focus on the satellites.
If you have a smaller number of larger MEO platforms (and they need to be larger to accommodate instruments that can to do their job from further away) your much more vulnerable to having large parts of your system knocked out. These larger platforms will also cost more, so you have less redundancy, higher costs, and are more vulnerable when your system will be needed most. The final systemic risk element is the post action debris risk… if a war goes hot and someone starts chucking ASAT weapons around, then we’re going to have a pile of debris, the sort of debris left behind by a kinetic kill ASAT in medium earth orbit is easily an order of magnitude more of an issue to other satellites for decades to centuries, it’s further away from all the existing space surveillance radar and optical systems on the ground making it harder to track the kind of small high velocity shrapnel that will have spread furthest away from the original orbit, which complicates the replacement of any destroyed space based assets as it will take longer to work out new safe orbits. LEO assets on the other hand have much shorter debris risk lifetimes, decades is usually the case as opposed to centuries, and LEO is much easier to track higher risk shrapnel debris down below 10cm, leading to better operational safety before and after a potentially satellite destroying hot war, meaning they are more likely to have a working system when needed and be able to replace it faster when damaged.
It’s a logical and reasonable argument on several fronts. However I do still agree with the assessment that eventually if the military has a sophistication LEO fleet of hundreds or thousands of Starlink style satellites, they are basically half way to the Star Wars “Brilliant Pebbles” architecture and it won’t be long until someone tries to build the other half of the architecture assuming they aren’t already planning this.
Unless you have a plan that involves using violence at a time of your choosing, the temporary advantage you get from deploying a new solution is mostly just peace of mind for a very small group of space force nerds until the adversary adapts.
And the sort of "worst case" imaging we're talking about here, the kind that makes you think the MEO sats that are part of the nuclear early warning system will be attacked in the first place, _absolutely_ compels you to assume the adversary will adapt in time.
Another important point here is that "systemic risk" here really only means "risk to US space systems of dubious utility", and nothing so grand as international deterrence or even international stability: jamming can a perfectly fine solution to ensuring the space based information is not timely available to US forces, and it's not like the timelines SIBRIS gives you are competitive with what good humint around intentions can give you.
Fun fast: the largest US satellite imagery provider, Maxar, was founded by the technical program lead for Brilliant Pebbles. It’s a small world and history rhymes.
I can’t comment on Griffin or the history of SDA, but proliferated LEO targets are much harder to take out with an ASAT than a small number of MEO or GEO satellites that are practically sitting ducks. If it costs ~$10M to take out a ~$1B asset, it’s gonna be the first thing to go in an apocalyptic scenario.
A LEO satellite can be hit directly with relatively cheap surface to air missiles in a matter of minutes (e.g., RIM-161). Getting to space for the ASAT takes much less energy than putting something into orbit. On the other hand, MEO and GEO satellites take a long time, many orbits, to interact with.. would even have enough time to summon ambassadors and ask questions.
For these "proliferated LEO constellations" an adversary just needs to punch a hole in the mesh immediately before launching an attack.
The fact is, putting HAWC-style interceptors in space (that could also of course be used offensively) hovering over every country on Earth, is incredibly aggressive and provocative. Everything is accelerated and mistakes will be made on both sides. It's fundamentally destabilizing (as the link above concludes). We've been down this road before and collectively decided its a terrible idea (Brilliant Pebbles). Helping SDA means furthering a dangerous future.
The whole thing seems built on deceit.