New Space Launch System has a New Design

[Retired_for_now]

There are advantages to a big throw weight and really big payload fairings. We're still struggling with practical mission concepts for long range space flight. Earth direct to anywhere is just a stunt. It won't pay until we prove out the long-duration habitats that can get us to the outer planets and exploit the resources outside our (expensive) gravity well. Rather than attack space mission that "go nowhere" we should consider history - Apollo missions went to Earth orbit, played with the LEM, rounded the moon, rounded the moon while playing with the LEM, then finally landed. Getting to Mars and beyond should be approached similarly. Living in ISS and keeping it running tells us how to make a habitat that will get there and back. Getting out to near Earth asteroids is more practice and potentially resources.

If nothing else the SLS provides engineering experience (and experienced engineers) that SpaceX will hire away and make money with. There's gold (and more valuable stuff) in them thar' asteroids!
Yogi

[luke strawwalker]

Originally Posted by Retired_for_now

There are advantages to a big throw weight and really big payload fairings. We're still struggling with practical mission concepts for long range space flight. Earth direct to anywhere is just a stunt. It won't pay until we prove out the long-duration habitats that can get us to the outer planets and exploit the resources outside our (expensive) gravity well. Rather than attack space mission that "go nowhere" we should consider history - Apollo missions went to Earth orbit, played with the LEM, rounded the moon, rounded the moon while playing with the LEM, then finally landed. Getting to Mars and beyond should be approached similarly. Living in ISS and keeping it running tells us how to make a habitat that will get there and back. Getting out to near Earth asteroids is more practice and potentially resources.

If nothing else the SLS provides engineering experience (and experienced engineers) that SpaceX will hire away and make money with. There's gold (and more valuable stuff) in them thar' asteroids!
Yogi

To a point... there's an advantage to big throw weights and payload fairings, but not if it's the most expensive rocket ever conceived... and not if there's no payloads to launch with it, and no money left for payloads or missions to launch with it.

Because SLS will only launch ONCE every 2-3 years, even at the best flight rates NASA can envision for it, it's going to be breathtakingly expensive. Basically most all the expenses of the shuttle program (SSME programs, SRB programs, ET (core stage) programs, plus the Orion program building a one-time-use spacecraft for every mission versus the Shuttle Orbiter program, which was a very expensive though "reusable" vehicle, so that's probably a wash...) Shuttle at least had the benefit of flying often, keeping the flight rates up enough to amortize a lot of the overhead expenses necessary to keep the shuttle capability going. SLS will have to bear multiple YEARS of overhead to keep the capability available, but only with a single flight to show for it... this will make each flight breathtakingly expensive (up to a billion per flight numbers have been bandied about).

For this reason alone, it's unlikely SLS will survive... it's simply too expensive a system for what it offers, versus what it costs to simply keep it as an operational system. NASA's DRM (direct reference mission) mission model for getting to Mars currently would require upwards of six SLS launches to assemble the spacecraft stack and launch the crew to rendezvous and dock with it and depart for Mars... Even if NASA doubles their every-other-year launch rate and launched one per year, it would take six years to assemble the Mars vehicle in Earth orbit. Double the launch rate again, it'd still take three years (at two launches per year) to assemble a Mars stack and send it on its way... And after all that, it STILL requires MULTIPLE launches, and assembly on orbit of the massive Mars vehicle stack...

SO, instead of six launches of a gigantic booster with even more gigantic costs, why not simply use a dozen launches of a smaller rocket?? Higher flight rates reduce costs, up to the capacity of the available infrastructure to construct and launch the vehicles without a major upgrade to the capabilities, which adds overhead... The argument for a "mega-booster" was to avoid costly and problematic assembly on orbit and launch all in one go, similar to Apollo... only problem is, there isn't a booster that's been built (including SLS) capable of launching an entire Mars mission in one launch. Therefore, assembly on orbit is a basic requirement. Granted, minimizing the launches and assembly steps IS a good goal to have-- ISS, if nothing else, has taught us that much... (Had Saturn V been available, we could have launched the equivalent station mass of ISS in only about five or six launches, versus the nearly 40 launches required to launch and assemble ISS from 1998 until 2011).

As for ISS, it's not teaching us that much in regards to Mars... Mars missions will not have the luxury of resupply flights every few months to bring up new supplies and materials and replacement components and such... Nor is it operating in a deep-space environment outside Earth's magnetic field... Something like the "gateway station" proposed for one of the lunar Lagrangian libration points (like EML-2) would be a far closer facsimile to the operating conditions for a trans-Mars or trans-asteroid spacecraft, yet nothing like that seems capable of getting past the proposal stage.

As for "gold in them thar asteroids", while proposals exist for asteroid mining and such, NONE of them hold any chance of profitability until we can create a low-cost, sustainable, high-flight-rate Earth to orbit launch capability-- and SLS will NOT do that, in any way, shape, or form...

Later! OL JR

[Retired_for_now]

Good points - but I remain optimistic about the big picture. The core issue remains, as you noted in several places, infrastructure. SLS or not, space travel is hard and expensive. A few SLS launches or lots of SpaceX Falcons, either will work. The real problem is getting a program of many launches spaced over several years funded and sustained. So, the necessary steps and infrastructure leading to deep space missions might need to "pay" for themselves.
I would disagree on ISS. We haven't built in any self-sustaining features other than the power system (where are the greenhouses and artificial gravity sections?). However, we are learning a lot about all the housekeeping systems needed for habitation, what supplies need to be carried versus can be recycled, etc. The ISS is driving cheaper launches though the resupply program and keeping the nations of the world working together for a future.
Nothing is perfect, I'm just looking for indications of progress.
Yogi

[godai]

Wait for the Russians to disconnect RUSegment and put up OPSEK, then USA will fly anywhere and there will be money for that

On the other hand, Russia can't even get aroung to putting up Nauka right now...