Dumb question:People are so used to thinking about what is required to get out of the atmosphere fast then they might not have much background for what is required here.Maybe some brainstorming is required to list unlikely variables and there are plenty of people on this site like me with no credibility to lose and can provide the raw material:If the purpose of the reentry burn is bow shock modification rather than direct velocity reduction then could other behaviours be at play?Unfortunately the only variable I can think they have to play with is the fuel mixture (more RP1 less O2) and its interaction with the tenuous hypersonic air and can't see why that would make any difference. Is it possible to pulse fire these engines?Any other variables possible - ?
From the UPDATE thread, jacqmans posted the attached image.Question: The hazard area only extends out by 63 NM? So any ASDS landing attempt places the barge no farther than 63 NM from the Cape, or is there a second zone farther downrange for the landing attempt?
Here's the FCC STA for the launch (F9-22), which doesn't include the ASDS radios:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=68937&RequestTimeout=1000
Quote from: Johnnyhinbos on 02/15/2016 04:36 pmFrom the UPDATE thread, jacqmans posted the attached image.Question: The hazard area only extends out by 63 NM? So any ASDS landing attempt places the barge no farther than 63 NM from the Cape, or is there a second zone farther downrange for the landing attempt?This is only the close inshore safety zone. There's another one for the potential debris impact areas/1st stage landing area further out. See the lower inset of the map image. "CG [Coast Guard] Safety Zone B per 33 CFR 165.775 active 6:01pm to 8:39pm, 24 Feb 16." Quote from: mvpel on 02/15/2016 05:10 pmHere's the FCC STA for the launch (F9-22), which doesn't include the ASDS radios:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=68937&RequestTimeout=1000The FCC authorization for the ASDS segment (recovery/landing) is covered in a separate grant:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000
Quote from: deruch on 02/16/2016 07:13 amQuote from: Johnnyhinbos on 02/15/2016 04:36 pmFrom the UPDATE thread, jacqmans posted the attached image.Question: The hazard area only extends out by 63 NM? So any ASDS landing attempt places the barge no farther than 63 NM from the Cape, or is there a second zone farther downrange for the landing attempt?This is only the close inshore safety zone. There's another one for the potential debris impact areas/1st stage landing area further out. See the lower inset of the map image. "CG [Coast Guard] Safety Zone B per 33 CFR 165.775 active 6:01pm to 8:39pm, 24 Feb 16." Quote from: mvpel on 02/15/2016 05:10 pmHere's the FCC STA for the launch (F9-22), which doesn't include the ASDS radios:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=68937&RequestTimeout=1000The FCC authorization for the ASDS segment (recovery/landing) is covered in a separate grant:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000Yikes! 28 16 10 North, 73 49 5 West is definitely out there! That's like, what, 400 NM due east? (That's a rough guess). Thanks for that link. Now we know right where the barge is going and can calculate departure time.
Those are definitely not compression artifacts. I'll be as bold as to claim it's not even a readout artifact from the chip i.e. something like the rolling shutter effect with CMOS chips. Given this is interlaced input video, it's virtually certain this is a CCD chip and so it doesn't suffer from such pixel readout timing variations.
The statement was never that "no recovery attempt would take place". The statement was that they are attempting a more risky recovery in order to give ses-9 a more advantageous orbit. Let's not turn into an echo chamber of false information.Wrt to your main point: assuming this application hasn't been amended and does in fact predate the SES press release, possible interpretations:1. The new launch plan was in the works for some time, and got announced only after it was "final".1b. Ditto, but the announcement was primarily timed for SES's investors (dont they have a quarterly earnings call coming up?).2. The plan all along was for no boostback burn, but the SES announcement/new plan was to shorten the reentry burn as well (this has been debated at length here on NSF).Other thoughts on ways to reconcile the timing... assuming there's anything here to reconcile?
Quote from: cscott on 02/16/2016 12:46 pmThe statement was never that "no recovery attempt would take place". The statement was that they are attempting a more risky recovery in order to give ses-9 a more advantageous orbit. Let's not turn into an echo chamber of false information.Wrt to your main point: assuming this application hasn't been amended and does in fact predate the SES press release, possible interpretations:1. The new launch plan was in the works for some time, and got announced only after it was "final".1b. Ditto, but the announcement was primarily timed for SES's investors (dont they have a quarterly earnings call coming up?).2. The plan all along was for no boostback burn, but the SES announcement/new plan was to shorten the reentry burn as well (this has been debated at length here on NSF).Other thoughts on ways to reconcile the timing... assuming there's anything here to reconcile?Another thing I don't quite understand: a couple of pre- FT hazard areas had centers around 500 mile downrange, so I was expecting the FT upgrade with its higher staging velocity to have a landing zone even farther out (assuming no boostback burn).
FT version has lower staging velocity than 1.1 version;
This means stage 2 is doing greater part of the total work, and means lower staging velocity.
Agreed that it doesn't look like a compression artifact, but I think you have CCD and CMOS reversed here.
Stage 1 tank size did not increase so all the propellant increase is due subcooling, but stage2 tank was extended. This means stage 2 is doing greater part of the total work, and means lower staging velocity.
Quote from: Exastro on 02/16/2016 01:05 pmAgreed that it doesn't look like a compression artifact, but I think you have CCD and CMOS reversed here. I don't think I have. CCDs integrate over the entire chip at once and if the exposure duration is >> than the time it takes to readout/store into another buffer, the only side-effect is a ghostly readout smear, oriented vertically or horizontally, depending on how the frame is transferred. CCDs are not susceptible to a rolling shutter as a result, however they are more expensive and are more susceptible to charge bleed artifacts.
Quote from: ugordan on 02/16/2016 01:44 pmQuote from: Exastro on 02/16/2016 01:05 pmAgreed that it doesn't look like a compression artifact, but I think you have CCD and CMOS reversed here. I don't think I have. CCDs integrate over the entire chip at once and if the exposure duration is >> than the time it takes to readout/store into another buffer, the only side-effect is a ghostly readout smear, oriented vertically or horizontally, depending on how the frame is transferred. CCDs are not susceptible to a rolling shutter as a result, however they are more expensive and are more susceptible to charge bleed artifacts.Once you get to the silicon, CMOS uses CCD's. The CMOS bit provides readout silicon, which isn't present on CCD's, which need a separate system. The way the readout is done will affect things like the rolling shutter as described.
CCD is the readout method, not the detection method. CCDs shuffle the charge to the edge for A-to-D, while CMOS reads them in-place. Perhaps you meant to say once you get to the silicon, CMOS and CCDs both use photodiodes.
Quote from: deruch on 02/16/2016 07:13 amThe FCC authorization for the ASDS segment (recovery/landing) is covered in a separate grant:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000Yikes! 28 16 10 North, 73 49 5 West is definitely out there! That's like, what, 400 NM due east? (That's a rough guess). Thanks for that link. Now we know right where the barge is going and can calculate departure time.
The FCC authorization for the ASDS segment (recovery/landing) is covered in a separate grant:https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000
Also, Johnny, can the radio scanning app you gave us for ORBCOMM ASDS & support tracking get us onto the 2090.00000000-MHz radio frequency, or do you or anyone know of an app that can?
Quote from: CyndyC on 02/16/2016 07:49 pmAlso, Johnny, can the radio scanning app you gave us for ORBCOMM ASDS & support tracking get us onto the 2090.00000000-MHz radio frequency, or do you or anyone know of an app that can? That is S-Band and not a typical scanner frequency. And also, it would not be voice.