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#700
by
SoftwareDude
on 27 Jun, 2024 23:59
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I just got caught up on the last week or so. I know a lot of this is redundant, but I'm going to try to summarize my understanding, to help myself process the information, and hopefully provide the same benefit to other readers. This is based mainly based on the June 18th teleconference, and the June 21st press release. Please do correct anything I may have misunderstood.
Landing Date Target
- Delay is driven by a desire to troubleshoot and understand the issues with the service module.
- After undocking and separation, the opportunity to do further tests with this exact hardware is permanently lost, because the service module burns up.
- Previous NET date of 6/26 was driven by range availability at White Sands for landing.
- Decided not to use 6/26 due to avoid constraining planned station activities, including EVA's (which if I remember right, are multi-day activities, due to the all the prep-work required, including acclimatization in the airlock before and after).
- Statements seemed to conflict about whether safety concerns were delaying the launch. It seemed to be implied that ongoing safety evaluations are also a factor in the return date, but also stated that the helium leak and 1 thruster being down are within the flight rules for undocking and re-entry.
- An agency level review is in progress to formally document acceptance of the plan to proceed.
- Landing opportunities repeat every 4 days.
Helium Leaks
- Leak does not continue when system is deactivated - isolation valves are closed.
- Leak rate was lower during docked hot fires than during rendezvous.
- Undocking through de-orbit burn requires helium system operation for 7 hours. There is enough helium for 70 hours.
Thrusters "failing off" (NASA's description) / "de-selected" (Boeing's description)
- 5 aft RCS thrusters failed off during final phase of rendezvous, after TPI burn
- Thruster B1A3 only showed 11% and 0% thrust during two firings during rendezvous. That thruster will not be fired again.
- Other thrusters showed reduced performance and were "de-selected" by the flight control system.
- Current theory is that heat from numerous thruster firings for rendezvous led to a portion of the propellant to be injected into the thruster as vapor instead of droplets, resulting in less consistent mixing.
- 7 remaining aft thrusters all hot fired for 1/4 second pulse after docking, including 3 that behaved nominally.
- Chamber pressure telemetry is 10 Hz (only 2-3 data points during the hot fire test), so not able to see full thrust profile and confirm peak pressure, but 3 definitely did reach 100% (300psi), and the rest appeared close.
- Engineers are comparing to OFT-2, when 2 thrusters failed during rendezvous, but continued working later. Crew 1 had more thruster firings, and fired them more rapidly.
- ISS Guidance, Navigation, and Control system data also being used to validate thruster hot fire test performance.
- Team confirmed vehicle is ok to perform an emergency undock if needed.
Misc
- Canadarm also performed an inspection of the thrusters. Nothing of note.
- Some ISS EVA water will be transferred to Starliner for its sublimator. It was not stated if this is due to the longer than originally planned flight duration or something else.
- 77 of 87 flight test objectives have been completed. The rest occur during undocking, re-entry, and landing
- Starliner cross-range ability for re-entry and landing is +/- 50km.
There were also two electrical problems.
First, a seemingly minor problem was on the ground. When the Starliner switched to internal power, the suit fans stopped working, and something had to be rebooted.
Second, happened after capture and connection with ISS and was a loss of power to one or more systems. There was a question to Butch from the ground about what he was doing when it happened.
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#701
by
iamlucky13
on 28 Jun, 2024 01:07
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I just got caught up on the last week or so. I know a lot of this is redundant, but I'm going to try to summarize my understanding
....
Misc
- Canadarm also performed an inspection of the thrusters. Nothing of note.
- Some ISS EVA water will be transferred to Starliner for its sublimator. It was not stated if this is due to the longer than originally planned flight duration or something else.
- 77 of 87 flight test objectives have been completed. The rest occur during undocking, re-entry, and landing
- Starliner cross-range ability for re-entry and landing is +/- 50km.
- An electrical issue before launch caused suit fans to stop working until some system was restarted.
- An electrical issue after capture and connection with ISS resulted in loss of power to one or more systems. Awaiting further details.
There were also two electrical problems.
First, a seemingly minor problem was on the ground. When the Starliner switched to internal power, the suit fans stopped working, and something had to be rebooted.
Second, happened after capture and connection with ISS and was a loss of power to one or more systems. There was a question to Butch from the ground about what he was doing when it happened.
Thank you. Since those were not mentioned in the teleconference or the June 21 rescheduling press release unless I missed them, my current assumption is those electrical issues are not factoring into return date discussions. Therefore I will edit my post to mention them in the Misc section.
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#702
by
abaddon
on 28 Jun, 2024 02:10
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I am going to hope the timing of the presser on Friday afternoon isn’t due to following the common practice of burying bad news right before the weekend….
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#703
by
Vettedrmr
on 28 Jun, 2024 02:19
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I am going to hope the timing of the presser on Friday afternoon isn’t due to following the common practice of burying bad news right before the weekend….
If that's their strategy it hasn't been working very well.
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#704
by
FutureSpaceTourist
on 28 Jun, 2024 11:57
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#705
by
Galactic Penguin SST
on 28 Jun, 2024 12:46
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If I am one of the presser's attenders, I would definitely want to ask what kind of progress do they want in the propulsion systems investigation before they can really clear Starliner for re-entry.
Like I fully understand this is pretty much more of "holding re-entry back until they are absolutely sure they don't need more in-orbit propulsion systems tests and prevent prolonged delays in certification" than any specific problem that blocks the way for the spacecraft to come back with people safely, but you really can't tell people that holding the spacecraft up in the ISS for an extra month over the planned 1 week is operationally reassuring.
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#706
by
zoey
on 28 Jun, 2024 13:04
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#707
by
rdale
on 28 Jun, 2024 13:06
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No need to suggest it's extra risky without supporting info. How about we wait until 2pm to hear the details?
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#708
by
FutureSpaceTourist
on 28 Jun, 2024 13:28
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https://twitter.com/sciguyspace/status/1806672865590428127In many discussions I have yet to talk with someone I deem credible on these issues who believes the Starliner issues are showstoppers. They believe the vehicle is safe. But another long delay, pushing close to the 45-day limit, is a bit at odds with that.
Taking more time to collect and assess data on the Service Module is a perfectly reasonable explanation for the delay. But the obvious question then is why did Boeing and NASA previously set return dates in mid- and late-June?
I make July 15th 40 days since launch so, allowing for potential weather delays, that seems about the latest target to return without having to justify extending the 45 days duration.
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#709
by
Galactic Penguin SST
on 28 Jun, 2024 14:42
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#710
by
DanClemmensen
on 28 Jun, 2024 14:57
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No need to suggest it's extra risky without supporting info. How about we wait until 2pm to hear the details?
True. Also no public info to allow us to assume it is not extra risky. We outsiders just don't know. I'm guessing the NASA/Boeing team do not have as much data as the would like to make this assessment, Therefore I would like some insight as to how they intend to make the decision.
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#711
by
DanClemmensen
on 28 Jun, 2024 15:04
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[Berger tweet]
In many discussions I have yet to talk with someone I deem credible on these issues who believes the Starliner issues are showstoppers. They believe the vehicle is safe. But another long delay, pushing close to the 45-day limit, is a bit at odds with that.
Taking more time to collect and assess data on the Service Module is a perfectly reasonable explanation for the delay. But the obvious question then is why did Boeing and NASA previously set return dates in mid- and late-June?
I make July 15th 40 days since launch so, allowing for potential weather delays, that seems about the latest target to return without having to justify extending the 45 days duration.
The keyword is "believe". They cannot be certain, so they are taking the extra time to see if there is a way to increase their confidence. This is the most reasonable approach and I do not think it should raise our level of concern at all.
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#712
by
Targeteer
on 28 Jun, 2024 18:07
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telemedia conference underway
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#713
by
FutureSpaceTourist
on 28 Jun, 2024 18:08
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#714
by
Targeteer
on 28 Jun, 2024 18:08
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the 45 day limit driver is the crew module batteries but analysis is ongoing to add another 45 days
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#715
by
Targeteer
on 28 Jun, 2024 18:11
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no change in leak rates, Starliner is not currently leaking helium because valves are closed
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#716
by
Targeteer
on 28 Jun, 2024 18:12
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thruster testing campaign planned at White Sands to examine thruster performance, testing may start Tuesday and 2 weeks of testing are planned. Landing planning will not start until the testing is complete.
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#717
by
FutureSpaceTourist
on 28 Jun, 2024 18:14
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https://twitter.com/cbs_spacenews/status/1806752988138234265Starliner CFT: NASA and Boeing have decided to carry out ground tests of a new thruster to mimic the same flight profile that was carried out in orbit when 5 aft-facing thrusters did not operate within pre-set limits specified in the spacecraft's flight control software during the approach to ISS; 4 of the 5 were later successfully test fired in space after the docking; test firings of the ground unit at White Sands, NM, are expected to begin next week
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#718
by
Targeteer
on 28 Jun, 2024 18:16
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EVA water leak still being investigated but could not be replicated. End of July for next EVA. Antenna move, gyro replacement, and microbial swabs are planned.
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#719
by
Targeteer
on 28 Jun, 2024 18:20
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Mark Nappi has a Google profile sending him Starliner stories every morning and he described reading them as depressing. He pleaded with the media to ask questions and stated flatly the crew is not stranded on ISS.