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#1460
by
mn
on 20 Jun, 2024 14:23
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Spaceflight is not perfected, and every launch opens the door to something going awry with Falcon 9 or Dragon.
F9 Block 5 is flying about 3 times a week, was first flown ins 2018, and has flown more than 290 missions without a failure. It's hard to think of a design failure that would ground the fleet.
It’s actually incredibly easy to think of dozens of failures that could do so. F9 has shown astonishing reliability, no question, especially amidst its epic, record-setting launch campaigns of the past several years.
But even if the odds of failure are demonstrably low, they are still odds, they exist. And every launch, whether Dragon or commercial or Starlink, represents another roll of the dice. Eventually an undesirable number will come up.
We do not have dissimilar redundancy now and have never had it in the past 25 years, except for Soyuz.
Don’t forget commercial resupply to ISS: Cargo Dragon on F9 and Cygnus on Antares or Atlas V.
Why should we keep wasting NASA's time and money (NASA oversight costs money) on Starliner? Maybe fund crewed Dream Chaser.
Okay, but that is making a very different argument.
I think you missed the point, obviously every launch could end in failure. But having flown successfully so many times, a failure should not lead to the typical 'grounding' that has been the norm in spaceflight in the past.
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#1461
by
EspenU
on 20 Jun, 2024 14:30
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I think you missed the point, obviously every launch could end in failure. But having flown successfully so many times, a failure should not lead to the typical 'grounding' that has been the norm in spaceflight in the past.
CRS-7 is a good example here. Not a design flaw, but supplier quality control issue.
The fix was quick, but a complex process of finding the root cause took months.
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#1462
by
deadman1204
on 20 Jun, 2024 14:45
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...
Also makes the case for universal suit life support ports.
Yes.
I'd love to hear a reporter ask about such contingency capability.
Without cross-compatible adapters, the dissimilar redundancy is almost as much a liability as it is a benefit.
And then what if that dragon fails, do we have another on stand by? Redundancy can be turtles ALL The way down. It quickly becomes incredibly expensive. I'd be frakked if nasa was spending time and money on spacex preparing a "resuce mission" when there was no need of it. Even the planning is not free, it takes time and money which could be spent elsewhere. Should nasa also be spending time/money on contingencies for a dragon failure?
I think there's been WAY to much disaster porn on youtube about epic failures and dragon miraculously rescuing stranded astronauts.
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#1463
by
DanClemmensen
on 20 Jun, 2024 14:50
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Why should we keep wasting NASA's time and money (NASA oversight costs money) on Starliner? Maybe fund crewed Dream Chaser.
Okay, but that is making a very different argument.
Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar redundancy has benefits, but it also has costs. The costs must be measured against the benefits. In the specific case of Starliner, costs are increasing and the benefits are decreasing.
Increased Costs: NASA resources (time and money for salary for increased oversight).
Decreased benefits: number of covered years is decreasing, while measured reliability of Crew Dragon is increasing so need for dissimilar redundancy is decreasing.
So: why are we spending my tax dollars on Starliner when there are better things to spend it on?
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#1464
by
Jim
on 20 Jun, 2024 14:52
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Why should we keep wasting NASA's time and money (NASA oversight costs money) on Starliner? Maybe fund crewed Dream Chaser.
Okay, but that is making a very different argument.
Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar redundancy has benefits, but it also has costs. The costs must be measured against the benefits. In the specific case of Starliner, costs are increasing and the benefits are decreasing.
Increased Costs: NASA resources (time and money for salary for increased oversight).
Decreased benefits: number of covered years is decreasing, while measured reliability of Crew Dragon is increasing so need for dissimilar redundancy is decreasing.
So: why are we spending my tax dollars on Starliner when there are better things to spend it on?
NASA resources are minor here.
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#1465
by
DanClemmensen
on 20 Jun, 2024 15:04
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Why should we keep wasting NASA's time and money (NASA oversight costs money) on Starliner? Maybe fund crewed Dream Chaser.
Okay, but that is making a very different argument.
Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar redundancy has benefits, but it also has costs. The costs must be measured against the benefits. In the specific case of Starliner, costs are increasing and the benefits are decreasing.
Increased Costs: NASA resources (time and money for salary for increased oversight).
Decreased benefits: number of covered years is decreasing, while measured reliability of Crew Dragon is increasing so need for dissimilar redundancy is decreasing.
So: why are we spending my tax dollars on Starliner when there are better things to spend it on?
NASA resources are minor here.
I recall seeing a report that NASA's increased Starliner program budget has been estimated at $325 million. "Minor" is a relative term.
Sorry, I cannot find that report, so maybe I'm miss-remembering.
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#1466
by
deadman1204
on 20 Jun, 2024 15:37
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Why should we keep wasting NASA's time and money (NASA oversight costs money) on Starliner? Maybe fund crewed Dream Chaser.
Okay, but that is making a very different argument.
Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar redundancy has benefits, but it also has costs. The costs must be measured against the benefits. In the specific case of Starliner, costs are increasing and the benefits are decreasing.
Increased Costs: NASA resources (time and money for salary for increased oversight).
Decreased benefits: number of covered years is decreasing, while measured reliability of Crew Dragon is increasing so need for dissimilar redundancy is decreasing.
So: why are we spending my tax dollars on Starliner when there are better things to spend it on?
NASA resources are minor here.
I recall seeing a report that NASA's increased Starliner program budget has been estimated at $325 million. "Minor" is a relative term.
Sorry, I cannot find that report, so maybe I'm miss-remembering.
Numbers without meaning. Starliner got a program boost severl years ago. That doesn't mean nasa is spending alot of money today on starliner. While it sucked, I think it was worth it, because redundancy is nice. Eventaully dragon will have a problem big enough to ground it for awhile, because thats the nature of the beast. Having starliner around will be a good thing.
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#1467
by
Vettedrmr
on 20 Jun, 2024 16:10
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Eventaully dragon will have a problem big enough to ground it for awhile, because thats the nature of the beast. Having starliner around will be a good thing.
1. We still don't have redundancy (excluding Soyuz for this debate), because Starliner isn't operational, yet.
2. Opportunities for this unknown "problem big enough to ground it for a while" are reducing with every completed mission on ISS.
Dis-similar redundancy is a good strategy long-term. That term is getting shorter.
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#1468
by
dglow
on 20 Jun, 2024 16:15
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I think you missed the point, obviously every launch could end in failure. But having flown successfully so many times, a failure should not lead to the typical 'grounding' that has been the norm in spaceflight in the past.
Sure, and it’s very reasonable to expect that SpaceX has a detailed POA should an F9 launch failure occur. I can easily imagine them resuming Starlink launches as soon as the FAA would grant approval.
But this thread is about Starliner and crew launches. My bet – and I’d ask all the industry vets to weigh in on this – is that, in the wake of an F9 failure, NASA would choose to stand down any imminent Crew Dragon mission and engage with SpaceX on a thorough and potentially time-consuming investigation. Tell me, why would we expect otherwise?
Before someone calls me out for injecting SpaceX into a Starliner thread, know that I do so only to
counter the argument that dissimilar redundancy, which for US crew to ISS means Starliner, is neither needed nor desirable.
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#1469
by
matthewkantar
on 20 Jun, 2024 16:20
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CNN doing a Henny Penny act, headline for a post on YouTube: ”Astronauts stuck on ISS as Boeing races to understand spacecraft issues.” They went to the trouble of getting an astronaut and a space journalist to interview and then post video with nonsense title.
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#1470
by
deadman1204
on 20 Jun, 2024 20:19
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Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar
Even if it was there, the space policy section is where topics go to die. You cannot have a discussion there because only a small subset of posters are even allowed to participate. Hence when people want to discuss space policy, it needs to show up in all the other areas too.
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#1471
by
clongton
on 20 Jun, 2024 22:27
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Actually, it's my only argument, and that's why it's in this thread instead of the space policy thread. Dissimilar
Even if it was there, the space policy section is where topics go to die. You cannot have a discussion there because only a small subset of posters are even allowed to participate. Hence when people want to discuss space policy, it needs to show up in all the other areas too.
Only to a point. Whatever is stated of a political nature must have a direct bearing on the thread topic. If it doesn't, it is off topic, should be deleted and the poster admonished.
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#1472
by
spacenut
on 20 Jun, 2024 22:37
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Can SpaceX send up a capsule with spacesuits to fit the two astronauts and rescue the two?
They are launching rockets every couple of days. Don't know if they have capsules already designated for specific crews or could build a capsule quickly enough to not delay any future launches.
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#1473
by
DanClemmensen
on 20 Jun, 2024 22:44
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Can SpaceX send up a capsule with spacesuits to fit the two astronauts and rescue the two?
They are launching rockets every couple of days. Don't know if they have capsules already designated for specific crews or could build a capsule quickly enough to not delay any future launches.
In the
very unlikely event of a rescue using Crew Dragon, that Dragon will launch with two empty seats. It will have plenty of room for those two suits. SpaceX has four Crew Dragons, and the rescue could be deferred. The simplest would be to fly Crew-9 (already scheduled for August) with only two crew.
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#1474
by
spacenut
on 21 Jun, 2024 00:35
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I would be afraid to come back in a leaking capsule. I know they may have enough helium to pressurize the hypergolic fuels, but it could get worse before coming back through the atmosphere. I was concerned a few years ago when SpaceX blew up one of their capsules while testing. Space is hard. Must have robust systems for humans.
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#1475
by
punder
on 21 Jun, 2024 00:48
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Starliner has dozens of thrusters. There’s no way that thing gets stuck in orbit—they will put together the angles and dV to get a reentry, even if they have to land in China, Siberia or the Indian Ocean.
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#1476
by
meekGee
on 21 Jun, 2024 01:24
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I would be afraid to come back in a leaking capsule. I know they may have enough helium to pressurize the hypergolic fuels, but it could get worse before coming back through the atmosphere. I was concerned a few years ago when SpaceX blew up one of their capsules while testing. Space is hard. Must have robust systems for humans.
Yeah, but realistically, for this flight, I think the He issue is known and not a show stopper. The only known that's of concern is the valves, and I'm sure by now they also know how much of an issue it is. Not worried. Unknown unknowns - They are always a concern in test flights, so just cross your fingers.
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#1477
by
Vettedrmr
on 21 Jun, 2024 01:27
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I would be afraid to come back in a leaking capsule. I know they may have enough helium to pressurize the hypergolic fuels, but it could get worse before coming back through the atmosphere. I was concerned a few years ago when SpaceX blew up one of their capsules while testing. Space is hard. Must have robust systems for humans.
AIUI the leaks are part of the SM, jettisoned well before re-entry.
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#1478
by
DanClemmensen
on 21 Jun, 2024 01:29
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Starliner has dozens of thrusters. There’s no way that thing gets stuck in orbit—they will put together the angles and dV to get a reentry, even if they have to land in China, Siberia or the Indian Ocean.
I seem to recall that it has 28 RCS thrusters. It also has four big RS-88 engines that it uses for launch abort. Are the RCS thruster the ones used for de-orbiting? The NASA real-time commentary during Starliner's approach to ISS showed a simulation graphic that included the thruster firing, and I think the big engines were used in addition to the RCS.
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#1479
by
kdhilliard
on 21 Jun, 2024 04:29
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...
I seem to recall that it has 28 RCS thrusters. It also has four big RS-88 engines that it uses for launch abort. Are the RCS thruster the ones used for de-orbiting?
No, not normally.
In addition to the 28 small RCS thrusters and the four very powerful RS-88 abort engines, the Service Module also has 20 mid-sized OMAC (Orbital Maneuvering and Attitude Control) thrusters.
(All four RS-88 abort engines and the RCS & OMAC thrusters on one of four doghouse are labeled in the first photo below.)
A standard de-orbit burn uses some combination of the 12 aft-facing OMAC thrusters.
But there are contingency RCS-thruster-only deorbit burns which use various combinations of the 8 aft-facing RCS thrusters.
Note that the Crew Module (the capsule itself) has an additional 12 RCS thrusters.
That's a total of 64 engines/thrusters! (Cf. Crew Dragon's 16 Draco thrusters + 8 Super Draco abort engines = 24 -- all recovered!)
The Starliner Crew Module's thrusters are used only for capsule orientation after Service Module separation and during reentry, and they are asymmetrically placed. (10 are visible in the second photo below, with the remaining two opposite the two visible on the left of the capsule.)
It was mentioned during Tuesday's presser that the Crew Module thrusters will be tested following Starliner's departure burn from the ISS.
I *assume* they were tested prior to docking, but I don't know.