As I understand things, the Commercial Crew Program stipulates full abort coverage from pad to orbit. An abort to the middle of the Atlantic ocean is understandably not acceptable.

Watching the OFT-2 launch, the abort location changes instantaneously from St. John's, Newfoundland to Shannon, Ireland at about MET 10:06:

I heard the webcast say that there is a 200 nmi (~370 km) radius from the port of call that the spacecraft must land in. The two locations are the same abort zones for SpaceX Crew Dragon launches too. The two locations are ~1700 nmi (~3150 km) apart at center, so about 1300 nmi (~2400 km) apart at the outer radii:

google Earth range

Here is a screenshot of the webcast right after this transition, showing the two abort zones, and the location and trajectory of the spacecraft:

webcast screenshot

It's unclear if the red trajectory prediction considers atmospheric effects or not. The spacecraft appears to be at ~150 km altitude and travelling at ~6.5 km/s (estimated from shown apoapsis & periapsis values).

Right before the abort zones switch, the trajectory prediction shows that the vehicle is going to go past the St. John's abort zone. What would an abort at this instant look like? How would the vehicle escape from the rocket and then turn around to thrust backwards towards St. John's?

Similarly, how much $\Delta V$ would it take from the abort system to kick the spacecraft the extra ~2000 km downrange to reach the Shannon abort zone?

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    $\begingroup$ You could estimate the Shannon-abort by looking at how quickly the prediction changes. Seems like less than 1 minute until the Shannon area is reached - that's what the abort system needs to provide. Likely a ~ 20-30 second burn at high g's. $\endgroup$
    – asdfex
    May 20, 2022 at 16:17
  • $\begingroup$ Regarding the question raised in the title (how does US crewed launch abort coverage "jump" the ocean in an instant), that's simple: The abort trajectories are different, and have to overlap in time. For example, the capability to abort to Shannon has to be feasible (but maybe a bit dicey) for some time prior to the transition to abort-to-Shannon mode, while the capability to abort to St. Johns has to be feasible (but maybe a bit dicey) for some time after to the transition to abort-to-Shannon mode. Diceyness factors include whether inadequate propellant and damage to the crew. (continued) $\endgroup$ May 20, 2022 at 20:27
  • $\begingroup$ The gold standard for success in rocketry is three sigma (99.73%) success. That sounds good, but it's not -- except for daredevils. Suppose 99.73% of commercial airplane flights did not crash. Nobody except a few daredevils would fly. Given pre-pandemic flight rates (~40 million flights per year), that would mean one hundred thousand commercial plane crashes per year. The pandemic has more than halved the flight rate, but that's still fives crashes per hour. Nobody would fly. $\endgroup$ May 20, 2022 at 20:40


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