Eric posted on the LinkedIn NASA group
If I remember the relevant discussions correctly, the Orion capsule by itself can be launched by the Atlas and Delta rockets, and possibly the Falcon 9 as well. It’s the launch abort system (LAS) that makes the system too heavy to launch on the existing EELV’s. This was one of the primary justifications given for developing the Ares I rocket in the first place. However, even its performance is extremely marginal. The design of the Orion capsule had to be scaled back a couple of times as the true capabilities of the Ares I became more clear.
The LAS is a hefty piece of kit, weighing somewhere between one-fourth and one-half as much as the Orion capsule (IIRC). That’s a pretty significant amount of payload that essentially gets jettisoned every launch without contributing anything to the nominal mission profile but peace of mind. It’s the insurance policy you pay for and hope you’ll never need.
Without the LAS, the remaining Orion capsule can be launched, unmanned, on top of a Delta or Atlas vehicle. Under the new plan, put forth by the current administration, Orion will be used to make cargo runs to the ISS, providing both up and down-mass capabilities. It may also serve as a backup lifeboat in case anything unfortunate should happen to either the station or the Soyuz docked at the station. NASA will be able to start getting some engineering data on Orion, and also begin incrementally introducing and testing out some more advanced technologies and capabilities that will eventually enable long duration crewed flight beyond LEO. Under the original Constellation plan, these developments would have had to wait until much later since all near term development funds were being consumed by the development of the Ares rockets. The continued development of the Orion is vital to NASA’s exploration plans since Orion is currently the only spacecraft designed to allow direct atmospheric reentry from beyond LEO. As such, it remains a crucial part of the Flexible Path architecture. By the time that NASA finally gets to build its heavy lift launch vehicle, it should be fairly straight forward to add the LAS and qualify the Orion for crewed ascent.
Personally, I prefer SpaceX’s approach to the LAS. For the Dragon, the LAS will be incorporated into the capsule itself, and can be used for more than just launch aborts. They should also be able to use it to do de-orbit burns and possibly retro-rocket powered landings. Not only are they getting more use out of the system during each mission, but if they are able to refurbish and relaunch the Dragon capsules, then that means the LAS/retro-rockets will also be reusable (i.e. do not have to be replaced for each mission). If you have to put that much mass on top of your rocket, you might as well get it all of the way into orbit and get some good use out of it.
I am hopeful that this is just the beginning of innovations we may be seeing from the private sector. The Apollo mode of throwing away 95% of the vehicle on each mission (and then not even reusing the 5% you get back), will no longer serve us if the goal is to create a sustainable presence in space. There must be a way to get much more use out of the hardware we put into space. Certainly, we must have spacecraft which can be used for long periods of time and for more than one mission, but it may also prove useful to re-imagine uses for spent stages and other hardware that would otherwise become abandoned space junk.
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