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.
Quote from: Proponent on 02/09/2017 11:57 amThe 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.Atlas 5 could not lift a 25 tonne Orion, and still can't. That's why. - Ed Kyle
It is capable to carry the CST-100 Starliner also by
The Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT.
Quote from: muomega0 on 02/09/2017 03:48 pmThe Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. You forgot the weight of the service module.
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?
Quote from: IRobot on 02/09/2017 08:51 pmQuote from: muomega0 on 02/09/2017 03:48 pmThe Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. You forgot the weight of the service module.And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.
Quote from: TakeOff on 02/09/2017 09:03 pmQuote from: IRobot on 02/09/2017 08:51 pmQuote from: muomega0 on 02/09/2017 03:48 pmThe Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. You forgot the weight of the service module.And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.Why count the launch escape tower (LAS) twice?
Quote from: TakeOff on 02/09/2017 09:03 pmQuote from: IRobot on 02/09/2017 08:51 pmQuote from: muomega0 on 02/09/2017 03:48 pmThe Orion capsule presently weights 10mT. With Solids, its LAS mass is about 10mT. You forgot the weight of the service module.And the launch escape tower. About three tons, isn't it? And it hopefully will detach on every successful launch.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. 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
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.
Quote from: TakeOff on 02/09/2017 11:51 amAtlas 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...