As for how quickly SpaceX can retarget the first stage to a different destination, recall that on an earlier flight, when the sea state was too rough to attempt a landing on the ASDS, the stage was re-targeted late in the count to land something like 10 km from the barge, onto the sea and away from the ASDS "flotilla".
So, I imagine they can retarget from the RTLS trajectory to one that targets the ASDS fairly late in the count, if weather or other conditions call for it.
They are in communication with the stage, so they should be able to switch as much as they want before stage separation.
As for how quickly SpaceX can retarget the first stage to a different destination, recall that on an earlier flight, when the sea state was too rough to attempt a landing on the ASDS, the stage was re-targeted late in the count to land something like 10 km from the barge, onto the sea and away from the ASDS "flotilla".
So, I imagine they can retarget from the RTLS trajectory to one that targets the ASDS fairly late in the count, if weather or other conditions call for it.
So if SX decides they want to blow it up in a spectacular way, who cares? It's no more of a loss than every other rocket delivery system ever.
Sure they could. But SpaceX has shown that they never waste an opportunity to learn. Which is why they have "landed" many stages in the ocean, even though they had no plan to recover them - real data to feed back into their simulations. And all it costs is a little extra fuel.
And no doubt SpaceX employees will be dancing in the aisles if they successfully deliver their customer payloads, yet fail to recover the 1st stage. They know what it takes to be allowed to continue experimenting...
They are in communication with the stage, so they should be able to switch as much as they want before stage separation.
The stage has no uplink capability. It tries to land at whatever coordinates are stored in it before launch.
Uplink would be risky because you cannot guarantee the stage will receive the uplink command, so there's chance the stage goes where you don't want it to, or vice versa. Safer and simpler to have 100% certainty ahead of time by loading/selecting the desired landing coordinates in the flight computer just before launch.
And if you don't know in the last few minutes of the count where you want to land, you have bigger problems. There's no way weather conditions are going to change so drastically in 10 minutes of flight time that you decide in-flight to land elsewhere.
They are in communication with the stage, so they should be able to switch as much as they want before stage separation.
The stage has no uplink capability. It tries to land at whatever coordinates are stored in it before launch.
Uplink would be risky because you cannot guarantee the stage will receive the uplink command, so there's chance the stage goes where you don't want it to, or vice versa. Safer and simpler to have 100% certainty ahead of time by loading/selecting the desired landing coordinates in the flight computer just before launch.
And if you don't know in the last few minutes of the count where you want to land, you have bigger problems. There's no way weather conditions are going to change so drastically in 10 minutes of flight time that you decide in-flight to land elsewhere.
There barge will in all likelihood be deployed for this flight. They can divert to the barge "at the last minute" (for a suitable definition of last).
The barge story does not end with a land landing. There are still plans to land F9 and FH stages far out to sea on performance-critical missions. Even if spurned this month, they will return. We'll see a sea landing at some point.
Answers my question! Thanks! I wasn't aware that the landing site could be switched "at the last minute," suitably defined. Fascinating! The vehicle it has, apparently, a lot of built-in guidance flexibility for targeting its landing location. I wonder to what extent different mission profiles (based on the mass of satellite(s), LEO or GTO) determines which platform to target. (But that's off topic for this thread.)
There barge will in all likelihood be deployed for this flight. They can divert to the barge "at the last minute" (for a suitable definition of last).
The barge story does not end with a land landing. There are still plans to land F9 and FH stages far out to sea on performance-critical missions. Even if spurned this month, they will return. We'll see a sea landing at some point.
Answers my question! Thanks! I wasn't aware that the landing site could be switched "at the last minute," suitably defined. Fascinating! The vehicle it has, apparently, a lot of built-in guidance flexibility for targeting its landing location. I wonder to what extent different mission profiles (based on the mass of satellite(s), LEO or GTO) determines which platform to target. (But that's off topic for this thread.)
Isn't this all conjecture? Is there any independent verification that the ASDS might be deployed for this launch?
At the minimum, they have uplink capability for the FTS. With all of the downlink capability (multiple video streams, telemetry, etc.) They definitely would be able to include a confirmation that commands are received. It is easy enough to keep resending until it is received correctly. It is possible that the FTS is too isolated to use its uplink antenna for this purpose. I would be a little surprised if they didn't have some other uplinks they send, but it is possible they don't.
I agree that there should be no reason to change the landing site after T-0, so they may not have bothered implementing this. On the other hand, they never expected a cargo dragon to be free flying during a launch failure, so they didn't give it parachute deploy option in that case. Using lessons learned, they might include a "switch landing site" command as a backup in case things go wrong (engine out leaves insufficient fuel for RTLS?).
I was mostly just stating the absolute last time it might be possible to perform the landing site decision.
There has been some argument from the 'older' rocket people about this. My thought is that even though current designs have no uplink to rearrange landing site. it will be useful as time goes by. There are reasons why you might want to change the landing site even up to stage separation, or even later. Perhaps an F9H, landing all three first stage cores at landing site, one core lands by crashes and upsets the second landing pad - you might want to tell subsequent cores to land further away, either on emergency pads, or perhaps even on a barge. Or perhaps a reentry burn isn't as good as expected, and you need to reassign the landing to somewhere it can actually reach, like an offshore barge.
There has been some argument from the 'older' rocket people about this. My thought is that even though current designs have no uplink to rearrange landing site. it will be useful as time goes by. There are reasons why you might want to change the landing site even up to stage separation, or even later. Perhaps an F9H, landing all three first stage cores at landing site, one core lands by crashes and upsets the second landing pad - you might want to tell subsequent cores to land further away, either on emergency pads, or perhaps even on a barge. Or perhaps a reentry burn isn't as good as expected, and you need to reassign the landing to somewhere it can actually reach, like an offshore barge.
No, none are valid reasons.
a. If the weather isn't good enough to launch, it isn't good enough to land.
b. There isn't going to be multiple pads to reassign inflight for FH mission.
c. They aren't going to send out the barge on missions not needing it.
There has been some argument from the 'older' rocket people about this. My thought is that even though current designs have no uplink to rearrange landing site. it will be useful as time goes by. There are reasons why you might want to change the landing site even up to stage separation, or even later. Perhaps an F9H, landing all three first stage cores at landing site, one core lands by crashes and upsets the second landing pad - you might want to tell subsequent cores to land further away, either on emergency pads, or perhaps even on a barge. Or perhaps a reentry burn isn't as good as expected, and you need to reassign the landing to somewhere it can actually reach, like an offshore barge.
No, none are valid reasons.
a. If the weather isn't good enough to launch, it isn't good enough to land.
b. There isn't going to be multiple pads to reassign inflight for FH mission.
c. They aren't going to send out the barge on missions not needing it.
a. I didn't mention weather. I agree with ' not fit to launch, not fit to land at LS', but there are other reasons why you might have to abort a landing at LS but still be able to land offshore.
b. Why not? High launch rates and possible damage to pads will mean there likely will need to be more than 3 at LS. Long term anyway.
c. Why not? It's cheap as a backup compared to the loss of a 1st stage.
Also, the range is not going to want a change in mid-flight.
a. I didn't mention weather. I agree with ' not fit to launch, not fit to land at LS', but there are other reasons why you might have to abort a landing at LS but still be able to land offshore.
b. Why not? High launch rates and possible damage to pads will mean there likely will need to be more than 3 at LS. Long term anyway.
c. Why not? It's cheap as a backup compared to the loss of a 1st stage.
a. Not really. There is nothing that requires a change between launch and boost back that requires an uplink. It can be done before launch.
b. What high launch rates? Even long term, still will be days between landings. And for FH, there isn't time to react for one booster to the other.
c. Not cheap. It takes resources and manpower. The factory has the manpower already. Anyways, resuse is not proven.
Hence, still no valid reasons. Not going to win this one either.
Also, the range is not going to want a change in mid-flight.
Also, the range is not going to want a change in mid-flight.
At one point, they must have been able to handle it, because isn't that exactly what a TAL or RTLS abort would have been?
Also, the range is not going to want a change in mid-flight.
At one point, they must have been able to handle it, because isn't that exactly what a TAL or RTLS abort would have been?
Lee Jay, I'm going to have to go with Jim on this one.
The difference between the Space Shuttle and the Falcon 9 first stage are pretty substantial, not the least being that the Shuttle was manned and could, in a pinch, be manually flown.
The Falcon 9 first stage, as I understand it, hasn't been configured to be flown either manually or by remote.