That's amazing. However their target is a fixed platform. Transferring a stage from one barge to another would require a different sort of compensation... When hooking the stage, the crane has to move in concert with the tip of the stage, but when setting the stage down the crane has to avoid penduluming but also get the stage to actually set down when the deck isn't moving under it a lot. Doable but a fun motion control problem to program.
I don't see any need to know the precise wind speed in the final moments before touchdown except for after-the-fact analysis (which IMHO they would need) because there's no way to make use of the data in real time.
using a ship-carrier to get the ASDS out on station a fair bit quicker than any "fast tug" could tow it.
Why are we making a big of this?A. The flight rate isn't going to be that high (for ASDS missions) to need the transfer.b. The problem was fixed long ago (it was designed for the open sea)
Quote from: CJ on 04/26/2016 08:39 pmI don't see any need to know the precise wind speed in the final moments before touchdown except for after-the-fact analysis (which IMHO they would need) because there's no way to make use of the data in real time.With adequate measurement upwind, you can get a complete picture of the wind and gusts in the next 5 seconds.This means that there are never any unexpected gusts, or winds in the last 5 seconds. (Or more strictly, the unknown magnitude is vastly smaller)You measure the wind environment in a shell around the craft, and build in these expected forces into your landing model, instead of assuming a simple constant wind field at the same value you measured 5s before landing.
Why are we making a big of this?A. The flight rate isn't going to be that high (for ASDS missions) to need the transfer.
The spirit of Rube Goldberg does not merely walk through this thread, it parades in grand style.
Quote from: CameronD on 04/26/2016 11:22 pmusing a ship-carrier to get the ASDS out on station a fair bit quicker than any "fast tug" could tow it.Once the ASDS was on that ship carrier then there would be no ship to ship motion so a crane mounted on the ship carrier could pluck the stage off the ASDS then return the empty ASDS to the water to catch another. BUT a) would still have pendulum motion to deal with while its hanging from the crane,
b) initial contact between the ASDS and ship carrier would be hellatious since they'd be moving in the waves differently (vs.normal loading in a calm harbor),
c) this is the max $$$$$ solution.
Given the inherently dangerous act of landing a rocket on a moving platform, I would think that the risk of having a barge get taken out and have no sea landing capability for a few weeks/months while it is repaired/replaced would motivate SpaceX to have at least some sort of contingency barge plan on stand-by that could be rapidly put into service.
The only absolutely necessary thing (IMHO) it couldn't do that an ASDS can is station keep, and that could be addressed via deep sea anchoring (regular anchors with very long anchor line, dropped well off each corner of the barge (about three times the depth) to keep it in place. This can be done in deep water (2000 or so feet is common in the usual recovery zone). It'd be very imperfect and ad-hoc, but might be worth the try vs. certain loss of the stage.
Quote from: CJ on 04/28/2016 01:29 am The only absolutely necessary thing (IMHO) it couldn't do that an ASDS can is station keep, and that could be addressed via deep sea anchoring (regular anchors with very long anchor line, dropped well off each corner of the barge (about three times the depth) to keep it in place. This can be done in deep water (2000 or so feet is common in the usual recovery zone). It'd be very imperfect and ad-hoc, but might be worth the try vs. certain loss of the stage. Not even enough to work.
My humble opinion... The cheapest solution here... is start the ball rolling on the OCISLY barge copy to be built for the upcoming Texas need...And charter much more powerful tugs to do "fast drags" of barges to where they are needed... as needed...Base whole east coast fleet out of Port Canaveral...For Texas launches... drag one down south of Miami and do a small boost forward if need be to reach it...Mix in some RTLS at both pad sites...Job Done... Just my opinion... edit... spelling