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Why wasn't Atlas V human rated as a replacement for the space shuttle? by TakeOff on 09 Feb, 2017 11:51
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Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.
Why was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?
EDIT: I removed an embarrassing brand name mistake. -
#1 by Proponent on 09 Feb, 2017 11:57
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The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").
Eventually the black-zone myth was debunked (see the attachment).
It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.
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#2 by edkyle99 on 09 Feb, 2017 15:36
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The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").
Atlas 5 could not lift a 25 tonne Orion, and still can't. That's why. (To date, the heaviest known Atlas 5 payload has only weighed a bit less than 7.5 tonnes.)
Eventually the black-zone myth was debunked (see the attachment).
It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.
Heavy would have been required. The lofted-trajectory "black zones" were only with single-engine Centaurs. Two-engine Centaur or a new upper stage with more thrust would have been needed.
Notice how the Starliner launch vehicle will use two RL-10s?
Also, when discussing the OP topic, keep in mind that when Shuttle was cancelled in January 2004 Atlas 5 had only flown three times.
- Ed Kyle -
#3 by muomega0 on 09 Feb, 2017 15:48
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The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. Because of the delay time in solids destruction, it makes it very difficult to achieve the 1:1000 LOC. Atlas has RD-180s. DOD did not want to alter its configuration for HSF. The major reason, was with propellant transfer and long term storage, you do not need HLV shuttle derived.The infamous ESAS study of 2005 (the one that recommended the 1.5-launch architecture for Constellation) claimed that EELVs were unsafe for crew launch, because their lofted trajectories meant crews would face unacceptably high G-loads during an abort in certain phases of flight ("black zones").
Atlas 5 could not lift a 25 tonne Orion, and still can't. That's why.
Eventually the black-zone myth was debunked (see the attachment).
It's hard not to suspect that ESAS's erroneous support for the existence of EELV black zones may have been motivated at some level, possibly subconscious, to justify Ares I.
- Ed Kyle
Any proposal to innovate in the LV industry fell on deaf ears for decades. Ever wonder why it was called 'Delta'? -
#4 by Jim on 09 Feb, 2017 17:45
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It is capable to carry the CST-100 Starliner also by
Boeing -
#5 by notsorandom on 09 Feb, 2017 20:45
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The Orbital Space Plane Program would have crew rated an EELV had the program continued.
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#6 by IRobot on 09 Feb, 2017 20:51
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You forgot the weight of the service module.
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. -
#7 by TakeOff on 09 Feb, 2017 21:03
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And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.
You forgot the weight of the service module.
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. -
#8 by Coastal Ron on 09 Feb, 2017 21:14
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Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.
While ULA has said both Atlas V and Delta IV Heavy can safely launch humans to space (ULA paper - date unknown), when the end of the Shuttle program was coming near the end and Ares I was having development challenges, ULA proposed Delta IV Heavy to be human rated. At the time (and I can't find the slide at this moment), ULA said it would be something like $1.4B to human rate and only take a couple of years.QuoteWhy was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?
I think Michael Griffin, the NASA Administrator at that point in history, is responsible for that decision. I think it was a bad one, but no need to debate it now... -
#9 by Danny Dot on 09 Feb, 2017 21:31
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I was a NASA engineer in the middle of all this at the time it happened. Atlas trajectories had no black zones from the start. The existing Delta trajectories had black zones. I requested we ask ULA/Boeing to lower the Delta trajectories but NASA management refused to ask ULA/Boeing to do this, even though the current trajectories made the Delta unacceptable. Several months later, ULA/Boeing somehow heard the current Delta trajectories were to high, and within 24 hours, had the trajectories low enough to close all black zones. The NSF archives have all this mess covered in detail. I am very glad I don't work there anymore.
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#10 by kch on 09 Feb, 2017 22:18
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And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.
You forgot the weight of the service module.
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT.
Why count the launch escape tower (LAS) twice? -
#11 by edkyle99 on 10 Feb, 2017 02:27
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In 2011, NASA JSC listed max mass at 35.38 tonnes, which included 7.64 tonne LAS, 10.39 tonne CM, 15.46 tonne SM, and 1.89 tonnes for adapters and fairings. CM + SM orbited mass was 25.85 tonnes.
And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.
You forgot the weight of the service module.
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT.
In 2014, the maximum "control mass" for Orion for SLS was given as 33.34 tonnes. This included the Crew Module, Service Module, Spacecraft Adapter and Launch Abort System.
The real number is probably a moving target, but remains somewhere in this ballpark.
For comparison, the heaviest mass ever lifted by an Atlas 5 was something like 7.5 tonnes for payload plus maybe 4.1 tonnes for fairing, a combined 11.3 tonnes. Black zones had nothing to do with it.
By the way, mighty Delta 4 Heavy only lifted maybe 19.8 tonnes during the EFT-1 launch including the dummy LAS and the SM panels and the adapter, and only put 11.5 to 12 tonnes into orbit. That's only halfway there ...
(To be fair, Delta 4 Heavy also orbited about 7 tonnes of propellant used for the second stage's second burn.)
- Ed Kyle -
#12 by rayleighscatter on 10 Feb, 2017 20:19
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It depends how you would want to define proven as well. When the Orion program began Atlas V had only launched 3 times.
Why was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V? -
#13 by muomega0 on 10 Feb, 2017 21:18
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If the LV has strap on solids, because of the delay time between their destruction and the abort, the LAS mass has to have more burn time to avoid the debris field as opposed to a LV with liquids.
Why count the launch escape tower (LAS) twice?
And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT.
You forgot the weight of the service module.
In 2009, a youtube video was published to explain the basics of abort on LAS mass.
Solids+Capules Increases LAS mass
In the deterministic simulations, the LAS mass increased to 22,000lbs so its overstated and as pointed out, requires probabilistic analysis.
This increase was clearly understood shortly after ESAS, yet it took 4 years to cancel CxP, and then they blamed the POTUS when Ares I could not get off the ground! No, it was not overweight Orion or thrust oscillation.
Sorry for overstating the mass. For the SM, its propellant could be offloaded with a LEO gas station. But right on que:
Thanks for pulling up the 2011 values. It became clear that Atlas Delta all had unique issues if they had to carry crew, so updates or new LVs like Vulcan would have been proposed perhaps a decade ago.
In 2011, NASA JSC listed max mass at 35.38 tonnes, which included 7.64 tonne LAS, 10.39 tonne CM, 15.46 tonne SM, and 1.89 tonnes for adapters and fairings. CM + SM orbited mass was 25.85 tonnes.
And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.
You forgot the weight of the service module.
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT.
In 2014, the maximum "control mass" for Orion for SLS was given as 33.34 tonnes. This included the Crew Module, Service Module, Spacecraft Adapter and Launch Abort System.
The real number is probably a moving target, but remains somewhere in this ballpark.
For comparison, the heaviest mass ever lifted by an Atlas 5 was something like 7.5 tonnes for payload plus maybe 4.1 tonnes for fairing, a combined 11.3 tonnes. Black zones had nothing to do with it.
By the way, mighty Delta 4 Heavy only lifted maybe 19.8 tonnes during the EFT-1 launch including the dummy LAS and the SM panels and the adapter, and only put 11.5 to 12 tonnes into orbit. That's only halfway there ...
(To be fair, Delta 4 Heavy also orbited about 7 tonnes of propellant used for the second stage's second burn.)
- Ed KyleI was a NASA engineer in the middle of all this at the time it happened. Atlas trajectories had no black zones from the start. The existing Delta trajectories had black zones. I requested we ask ULA/Boeing to lower the Delta trajectories but NASA management refused to ask ULA/Boeing to do this, even though the current trajectories made the Delta unacceptable. Several months later, ULA/Boeing somehow heard the current Delta trajectories were to high, and within 24 hours, had the trajectories low enough to close all black zones. The NSF archives have all this mess covered in detail. I am very glad I don't work there anymore.
Danny,
I want to thank you for taking the time and energy to speak up. Black Zones, AR&D Risk, LAS mass.... the list goes on....
Wayne Hale's Stiffling Dissent says it way better than I.
Thanks again.
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#14 by Sam Ho on 10 Feb, 2017 21:42
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Atlas V has an extraordinary reliable launch record. Why wasn't it upgraded to become certified for human spaceflight, especially when it was decided to cancel the STS space shuttle? It is capable to carry the CST-100 Starliner, so it is obviously intended to become human rated anyway now.
While ULA has said both Atlas V and Delta IV Heavy can safely launch humans to space (ULA paper - date unknown), when the end of the Shuttle program was coming near the end and Ares I was having development challenges, ULA proposed Delta IV Heavy to be human rated. At the time (and I can't find the slide at this moment), ULA said it would be something like $1.4B to human rate and only take a couple of years.QuoteWhy was Orion developed for a potential future much heavier launcher instead of for the already existing and proven Atlas V?
I think Michael Griffin, the NASA Administrator at that point in history, is responsible for that decision. I think it was a bad one, but no need to debate it now...
That ULA paper is from AIAA Space 2009. The $1.3B and 4.5 years quote is from the Augustine Commission presentation.
There's a number of existing threads in the ULA and Commercial Crew sections about the topic:
ULA Atlas V Human Rating/Commercial Crew Threads
http://forum.nasaspaceflight.com/index.php?topic=29755.0
NASA and ULA agree SAA to complete the human rating of Atlas V
http://forum.nasaspaceflight.com/index.php?topic=26059.0
Formation of ULA Human Launch Services Organization
http://forum.nasaspaceflight.com/index.php?topic=28588.0
NASA and ULA confirm Atlas V baseline for human rated launches
http://forum.nasaspaceflight.com/index.php?topic=29487.0
The Respected Rocket - Atlas V making the early strides of the transition
http://forum.nasaspaceflight.com/index.php?topic=27376.0
ULA has several additional papers, in addition to the one you mentioned:
http://www.ulalaunch.com/Education_PublishedPapers.aspx#Human_Rating
Commercial Crew Abort System Design Evolution and Validation (AIAA Space 2015)
Commercial Crew Launch Emergency Detection System: The Key Technology for Human Rating EELV
Enabling Crew Launch on Atlas V and Delta IV
Atlas Emergency Detection System
Atlas V: Safe and Affordable Human Spaceflight 2005-6706
Atlas V for Commercial Passenger Transportation 2006-7268
ELV Human Rating: Atlas Heritage and Future Potential 2005-3812
EELV Considerations - Briefing to the Review of U.S. Human Space Flight Plans Committee
Advantages of Heritage Atlas Systems for Human Spaceflight 2011
Evolution of Abort Management of Crewed Launch Vehicles 2011
Commercial Crew Development Enabling Launch on EELV 2011
