Well, how many threatening do we think we're going to be getting in our area, almost directly on the opposite side of the world as the projected impact zone? If we were based in Usea I imagine we'd need to deal with a hell of a lot greater quantity of fragments threatening us, but down here on the opposite side of Antarctica our interceptor systems should be much less stressed by potential impactors.
The problem is that if the interceptors are only intercepting rocks headed right for us, they are effectively useless against the bulk of the damage Ulysses is likely to cause to us.
Remember, the main threat we face is asteroids hitting the ocean, potentially thousands of kilometers away or even on the other side of the world, and causing tsunamis that mess up our coastline.
Which means we need to identify the rocks that will do that, and somehow engage them. We're going to be needing to either launch them "up" to hit asteroids that are still on orbital tracks but likely to decay and enter the atmosphere and hit the planet a few days before they actually crash down, or we're going to be launching them 'round the world' to engage asteroids that are in the process of falling into distant oceans where they would set off tidal waves that threaten us indirectly.
Joyeuse is chosen as something that plausibly has exo-atmospheric engagement capability; it can shoot asteroids that are still orbiting and on their way down, even if it is realistically incapable of meaningfully reducing the overall mass of Ulysses as a whole before it breaks up.
I feel like three planes where we can do a rotation of something like 24 hours ready/engaging followed by 48 hours rest and maintenance would allow for a enough down time to keep everything going, especially as that schedule doesn't have to hold indefinitely, just for 2 week of high tempo operations until the impacts stop, at which point we can increase the ratio of downtime to flight hours even further.
How do you keep a single interceptor fighter operating continuously for twenty-four hours?
I think we're probably going to need
several of these things, a squadron or more, just to make sure there's always one available and ready to launch as we identify new asteroid threats that need blowing up before they become a tsunami problem for us.
Also, for aircraft design like this, the R&D tends to be a huge up-front cost, and then the cost of actually building each plane to the design specifications is lower. I strongly suspect that if we have a 7500-point "build three superplanes" project, the breakdown will look like:
3000 points "design the superplane and its component technologies"
3000 points "build the test and production facilities for the bespoke hardware the superplane uses"
500 points "actually build a prototype that even begins to approach the capabilities of the intended superplane"
500 points "build the first superplane"
250 points "build another superplane" x2
Those are approximations, but that's about what I'd expect. At which point it costs us
relatively little to turn out a squadron's worth of the things.
At some point building additional DAWN SHEPHERD interceptors would be increasing the total scale of the project more than the extra airframes will provide defense, because presumably we're going to look into how many fragments across the protected area each of the three planes is likely going to have to intercept per "shift" and then design them to be capable of that, rather than the other way around where we design a plane and hope that it's enough to cover everything with just three of them. Producing enough airframes to fly 3 or 4 of them per shift isn't a very effective use of our resources if just 1 of them could cover all but the worst outlier situations, and 2 would cover those.
Given the sheer number of fragments we're expecting, having only one plane available and on duty to hit any target anywhere in the world for 24 hours at a stretch sounds... problematic.
Honestly, an Arkbird-like ALBATROSS project might be more practical in that regard, just because it's going to be
up in space the whole time Ulysses is coming down on the planet, rather than us needing to fly individual fighters across intercontinental distances to shoot down individual fragments that are spread out widely over the entire planet and its orbital space, then recover them and send them up again.
It's the downtime per plane that's the potential killer with DAWN SHEPHERD, and mass production of interceptors that's the solution, if you ask me.
