Author Topic: SpaceX Falcon 9 CRS/SpX-10 Dragon - Feb. 19, 2017 - Discussion (Read 418676 times)

Jim · « **Reply #700 on:** 02/21/2017 10:55 pm »

Something of note. Since this was an FAA licensed launch from KSC, there was no Air Force Launch Decision Authority. The range provided support but not range safety (AFTS took care of that).

abaddon · « **Reply #701 on:** 02/21/2017 11:01 pm »

Speaking of AFTS, I noticed the callout that the first-stage AFTS was safed before the stage went transonic on the re-entry. That was much further out than I had imagined. Is there no FTS at that point or do they revert to the shadow FTS? If no FTS, isn't that a bit soon for the FTS to be safed? Or would it be counterproductive to terminate the stage past that point, from a safety standpoint?

Herb Schaltegger · « **Reply #702 on:** 02/21/2017 11:13 pm »

Quote from: abaddon on 02/21/2017 11:01 pm

Speaking of AFTS, I noticed the callout that the first-stage AFTS was safed before the stage went transonic on the re-entry. That was much further out than I had imagined. Is there no FTS at that point or do they revert to the shadow FTS? If no FTS, isn't that a bit soon for the FTS to be safed? Or would it be counterproductive to terminate the stage past that point, from a safety standpoint?

I heard that call-out too. My supposition is that FTS is active when the IIP (instantaneous impact point) of the returning stage is on or near land, and then safed again during final descent once the IIP is safely inside LZ-1 with negligible rate of change, sufficient to ensure that if things go pear-shaped, it'll all be roughly contained within the landing area with no risk to people of other facilities.

russianhalo117 · « **Reply #703 on:** 02/21/2017 11:23 pm »

Quote from: abaddon on 02/21/2017 11:01 pm

Speaking of AFTS, I noticed the callout that the first-stage AFTS was safed before the stage went transonic on the re-entry. That was much further out than I had imagined. Is there no FTS at that point or do they revert to the shadow FTS? If no FTS, isn't that a bit soon for the FTS to be safed? Or would it be counterproductive to terminate the stage past that point, from a safety standpoint?

Both the primary and backup FTS systems are safed at the same time by the same command.

abaddon · « **Reply #704 on:** 02/21/2017 11:28 pm »

Thanks @HerbSchaltegger and @russianhalo117, both those comments make sense. I am just surprised it is safed so high, I guess. From the technical webcast:

21:45 AFTS safed
22:00 Stage transsonic
22:18 Landing burn start
22:48 Touchdown

(Note that some of these are a bit unreliable as the video of the landing from the ground is ahead of the stage camera and the touchdown callout is also ahead (but not as much) of the stage camera).

Regardless it must be as Herb suggests, so I guess they are just confident the landing burn and/or grid fins won't suddenly go crazy, or the control authority of the two combined along with the descent velocity would be unable to take it outside the confines of the landing zone...

mn · « **Reply #705 on:** 02/22/2017 12:06 am »

Seems like the air force is calling it AFSS not AFTS

https://m.facebook.com/AirForceSpaceCommand/posts/10154514359132074

russianhalo117 · « **Reply #706 on:** 02/22/2017 12:13 am »

Quote from: mn on 02/22/2017 12:06 am

Seems like the air force is calling it AFSS not AFTS

https://m.facebook.com/AirForceSpaceCommand/posts/10154514359132074

its both

vaporcobra · « **Reply #707 on:** 02/22/2017 07:54 am »

Anyone have any understanding of the Dragon's relative GPS and how an unconverged filter fits into the mechanism? In my layman comprehension, it sounds like it is possible that the problem could be with software or hardware based on the info we currently have from NASA.

HVM · « **Reply #708 on:** 02/22/2017 08:25 am »

Do any one catch that on NasaTV, "wrong hard drive" installation?

vaporcobra · « **Reply #709 on:** 02/22/2017 08:26 am »

Quote from: HVM on 02/22/2017 08:25 am

Do any one catch that on NasaTV, "wrong hard drive" installation?

Heard that haha. Sounds like that issue was fixed

Jarnis · « **Reply #710 on:** 02/22/2017 09:20 am »

Quote from: vaporcobra on 02/22/2017 07:54 am

Anyone have any understanding of the Dragon's relative GPS and how an unconverged filter fits into the mechanism? In my layman comprehension, it sounds like it is possible that the problem could be with software or hardware based on the info we currently have from NASA.

I think it looks like a typo or wrong data being sent up. Did someone forget the 1 day delay in the launch and didn't update the relevant bits?

FutureSpaceTourist · « **Reply #711 on:** 02/22/2017 09:37 am »

Oops! I hope the fix is that easy.

Good to see though that Dragon safety protocols worked; bodes well for commercial crew.

FutureSpaceTourist · « **Reply #712 on:** 02/22/2017 09:46 am »

Any implications for cargo with the one day launch delay and (hopefully) one day berthing delay?

I'm thinking particularly of late load items in fridges etc. How long before there's an issue with spoiling?

kevinof · « **Reply #713 on:** 02/22/2017 09:48 am »

Nasa TV said no implications for the mices(!) or any other cargo. Looks like some incorrect data was entered somewhere along the chain but nice to see the systems catch it and back off. Shame it had to be caught this late in the game though.

A12 · « **Reply #714 on:** 02/22/2017 10:23 am »

In the NASA tweet

https://twitter.com/NASA/status/834336113884012544

on the Dragon a dark spot is visible on the top.
Is it a shadow or what ?

ugordan · « **Reply #715 on:** 02/22/2017 10:26 am »

Quote from: A12 on 02/22/2017 10:23 am

In the NASA tweet

https://twitter.com/NASA/status/834336113884012544

on the Dragon a dark spot is visible on the top.
Is it a shadow or what ?

That may be an archive photo of a previous rendezvous and it would be a shadow of some part of the ISS.

DaveS · « **Reply #716 on:** 02/22/2017 10:28 am »

Quote from: A12 on 02/22/2017 10:23 am

In the NASA tweet

https://twitter.com/NASA/status/834336113884012544

on the Dragon a dark spot is visible on the top.
Is it a shadow or what ?

Yes, from one of the ISS modules.

Ben the Space Brit · « **Reply #717 on:** 02/22/2017 10:43 am »

Quote from: vaporcobra on 02/22/2017 08:08 am

Based on what was just said, it sounds like a prime suspect in the abort and unconverged filter is an incorrect value having been processed by Dragon's computers, that value regarding the vector and position of the ISS. So, plausibly a software issue (possibly human error-related, given Dragon's triple redundancy against cosmic ray bit-flipping).

Just out of interest, how would you fix something like this? I'm presuming that MCC-X at Hawthorne can just upload a revised and error-checked navigational data-set to the Dragon's computers and recommence the program.

rsdavis9 · « **Reply #718 on:** 02/22/2017 11:11 am »

So does anybody have or know where there is a timeline of loading of propellants and other pre launch events? I heard the callouts but it would be nice to see one list to see how they modified the loading to prevent the copv burst.

baldusi · « **Reply #719 on:** 02/22/2017 11:51 am »

Quote from: Herb Schaltegger on 02/21/2017 11:13 pm

Quote from: abaddon on 02/21/2017 11:01 pm
Speaking of AFTS, I noticed the callout that the first-stage AFTS was safed before the stage went transonic on the re-entry. That was much further out than I had imagined. Is there no FTS at that point or do they revert to the shadow FTS? If no FTS, isn't that a bit soon for the FTS to be safed? Or would it be counterproductive to terminate the stage past that point, from a safety standpoint?

I heard that call-out too. My supposition is that FTS is active when the IIP (instantaneous impact point) of the returning stage is on or near land, and then safed again during final descent once the IIP is safely inside LZ-1 with negligible rate of change, sufficient to ensure that if things go pear-shaped, it'll all be roughly contained within the landing area with no risk to people of other facilities.

If they IIP is in the sea, and the final burn is designed to push it just enough to the LZ, then it might be pretty safe to turn off the FTS.