Besides the difference between re-entry heating at 3km/s and 1.5 is 4 times!
Quote from: francesco nicoli on 02/09/2016 04:35 pmIn terms of PR, is it worthy to try recovery of with very low chances of success? big ground explosions are no good for SpaceX reputations, they would be flown by "fourth barge attempt explosion in a row" headlines everywhere.One alternative is that they don't mention the recovery attempt, i.e. use the "The F9 for this flight will be in expendable mode", and then attempt the landing anyway, ...And if it succeeds, then well, it's a win win and they can release some glorious footage...
In terms of PR, is it worthy to try recovery of with very low chances of success? big ground explosions are no good for SpaceX reputations, they would be flown by "fourth barge attempt explosion in a row" headlines everywhere.
Disregard energy management for a moment. In addition to that basic function, the boostback/slowdown and reentry burns also serve as trajectory correction maneuvers. Without them, there is a possibility that the uncertainty in the state vector at 1st stage cutoff would be too big for just the fins to compensate for during reentry phase. In short, I think there has to at least be a short reentry burn to aim toward the general area of the ASDS and then to rely on the fins for finer adjustments before landing burn.
The stage would be on an entirely ballistic trajectory prior to atmospheric reentry, so the trajectory uncertainty should be low.
Quote from: whitelancer64 on 02/09/2016 05:42 pmThe stage would be on an entirely ballistic trajectory prior to atmospheric reentry, so the trajectory uncertainty should be low. Why should/would it be low? That ballistic trajectory will have basically been set up several minutes earlier when staging happened so any state vector difference at that point to what the preflight staging predict was would have quite a bit of time to propagate into a bigger downrange impact point uncertainty. Of course I have no actual numbers to back any of this up.
@Lar if the attempt fails, they are likely going to arrive nowhere near the ASDS. Arriving close enough to damage the ASDS means that the landing attempt basically worked.
Quote from: cscott on 02/09/2016 04:58 pm@Lar if the attempt fails, they are likely going to arrive nowhere near the ASDS. Arriving close enough to damage the ASDS means that the landing attempt basically worked.The only scenario where that would *not* be the case is where it "almost worked" and the engine ran out early (or failed to start due to some damage from the additional heating it normally doesn't experience?) but the grid fins did a great job of guidance so the stage smacked right into the ASDS dead center at a good clip...
Okay yeah, but 20 tons of just about anything moving at hundreds of miles per hour would damage the barge significantly.But that's what the barge is for and why it's steel and not fiberglass. Weld the hole shut when you get back to shore.
Not to open a can of worms, but could they unzip the booster if it's determined to be more of an anti ASDS weapon rather then a lovely companion rocket, or can only the Range trigger the FTS
By the way - it could very easily do significant damage to the barge and systems. Look at the damage that the original JRTI sustained on the first landing attempt.
Not to open a can of worms, but could they unzip the booster if it's determined to be more of an anti ASDS weapon rather then a lovely companion rocket, or can only the Range trigger the FTS (and if so, would they initiate it in order to spare excessive damage to the barge).
Quote from: Johnnyhinbos on 02/09/2016 07:46 pmNot to open a can of worms, but could they unzip the booster if it's determined to be more of an anti ASDS weapon rather then a lovely companion rocket, or can only the Range trigger the FTS (and if so, would they initiate it in order to spare excessive damage to the barge). Also I think I heared "FTS is saved" on the radio in last missions prior to the lading attempt. I think its noted around the reentry burn. So no more FTS near the barge in any case.