Author Topic: What to replace SLS with if it's canceled  (Read 77602 times)

Offline deltaV

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What to replace SLS with if it's canceled
« on: 11/27/2016 09:53 pm »
There's a lot of discussion elsewhere about whether or not SLS should be canceled. This thread is about something less commonly discussed: what to replace SLS with.

Ground rules:
-Assume Trump decides to cancel SLS within the first 6-12 months of his term
-Assume NASA's HSF budget over the next 20 years has a similar trajectory to NASA's budget had over the previous 20 years, i.e. average growth of 2% per year in nominal terms.

Topics for discussion include:
-Launchers
-Cancel MPCV/Orion too?
-Other spacecraft
-Moon or Mars?

Offline spacetraveler

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Re: What to replace SLS with if it's canceled
« Reply #1 on: 11/27/2016 10:10 pm »
There is no need to cancel Orion as it could be launched with less powerful launchers.

And actually cancelling SLS would free up more money to keep it. But assuming we are actually serious about going to mars, where the money needs to go is all of the payloads that are not being developed right now that will be needed for that.

The path we are on right now will see SLS completed with nothing useful for it to launch.
« Last Edit: 11/27/2016 10:12 pm by spacetraveler »

Offline MATTBLAK

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Re: What to replace SLS with if it's canceled
« Reply #2 on: 11/27/2016 10:22 pm »
Vulcan with ACES upper stage. Period. 35 tons into Low Earth Orbit. And a Vulcan with 8x solid strap-on boosters would not be out of the question, however unlikely at this stage. An 8x booster Vulcan with more powerful upper stage engines should get about 50 tons into L.E.O. - manned lunar launches with a 3x launch Design Reference Mission, or 4x launches with a heavier Lunar Lander. 2x launches for cargo missions to the Lunar surface or crewed flights to a lunar gateway station or lunar orbit.

For Mars missions; Vulcan working in concert with Falcon Heavy or New Glenn - launching from 4x launchpads at KSC for mission elements assembly in L.E.O. Meaning, 2x launches from each pad.
« Last Edit: 11/27/2016 10:27 pm by MATTBLAK »
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Offline scienceguy

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Re: What to replace SLS with if it's canceled
« Reply #3 on: 11/27/2016 11:04 pm »
e^(pi*i) = -1

Offline edkyle99

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Re: What to replace SLS with if it's canceled
« Reply #4 on: 11/28/2016 12:34 am »
Canceling SLS would mean canceling Orion.  There is no replacement.  Canceling SLS would be a pointless national space program suicide. 

 - Ed Kyle
« Last Edit: 11/28/2016 12:39 am by edkyle99 »

Offline Coastal Ron

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Re: What to replace SLS with if it's canceled
« Reply #5 on: 11/28/2016 12:49 am »
There's a lot of discussion elsewhere about whether or not SLS should be canceled.

The only question that matters is whether the U.S. Government needs to move a large amount of payloads to space that can't fit on existing commercial launchers.

If the answer is no, then the SLS should be cancelled.   If the answer is yes, then maybe it shouldn't.  So far though the indications are that there is NOT enough U.S. Government demand to merit the U.S. Government owning and operating their own space transportation system.

Quote
This thread is about something less commonly discussed: what to replace SLS with.

If the U.S. Government doesn't have enough demand to merit owning and operating their own HLV, then there is no need to replace it with another U.S. Government-owned transportation system.

Which means the U.S. Government will rely on the U.S. aerospace sector to take care of it's needs - something that the U.S. aerospace sector should be more than capable of doing using their own transportation systems.

My $0.02
« Last Edit: 11/28/2016 02:36 am by Coastal Ron »
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline MATTBLAK

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Re: What to replace SLS with if it's canceled
« Reply #6 on: 11/28/2016 03:07 am »


Venturestar? Extremely unlikely, scienceguy.
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Offline MattMason

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Re: What to replace SLS with if it's canceled
« Reply #7 on: 11/28/2016 03:28 am »
My thoughts: Orion itself is designed for something the other CC spacecraft aren't: A long duration spaceflight command module. It's likely you can fly it on Falcon Heavy and certainly New Glenn and send payloads up separately in an earth-orbit rendezvous scenario.

SLS itself seemed to be a bit of a underfunded make-work program going nowhere in particular. Even if Orion is kept, it still hasn't a destination. But, development and testing of it can go full-throttle and private launchers can meet the need of what it can do in the current timeframe.

To save Commercial Crew and bolster private launchers while giving Orion more life, I'd nix SLS, too. If everything's cut, it's a gigantic waste of cash not seen since Ares/Constellation. SLS could be developed more slowly when we are fully ready to go to Mars--but by then, all kinds of LVs will be around.
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Offline deltaV

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Re: What to replace SLS with if it's canceled
« Reply #8 on: 11/28/2016 03:57 am »
Canceling SLS would mean canceling Orion.  There is no replacement.

There are four commercial super-heavy US launch vehicles under development:
-Vulcan Heavy
-New Glenn
-Falcon Heavy
-ITS

Wikipedia says Orion + Service Module is about 25 tonnes and 5m diameter. That should be well within the capabilities of all four launchers unless there's a problematic detail such as launch vibrations. Several of those launch vehicles have a lot of development left but Falcon Heavy is almost ready. Why do you say that canceling SLS implies canceling Orion?

Orion was originally a Moon capsule and AFAICT would do OK at that role. Orion doesn't seem very useful however for the Mars program of record. Therefore my two cents on Orion is we should cancel it if we continue with the Mars destination but keep Orion if we switch to the Moon.

It appears that the first three vehicles have similar performance: they’ll all be able to send about 20 tonnes to GTO. (Sources: https://twitter.com/torybruno/status/595628488410963970, http://forum.nasaspaceflight.com/index.php?topic=41146.msg1589576#msg1589576, http://www.spacex.com/falcon-heavy.) It seems unlikely that all three will get built but ISTM at least two vehicles of this class will be, especially if NASA throws a little funding and demand at them. New Glenn and Falcon Heavy seem like the most likely of the four to actually be built so maybe NASA should baseline them? Volume-wise anything that Falcon Heavy can launch New Glenn presumably can too (because of its almost 2x diameter). Which of the two is limiting mass-wise probably depends on target orbit, reusability choices, and whether Falcon Heavy gets cross-feed.

If the U.S. Government doesn't have enough demand to merit owning and operating their own HLV, then there is no need to replace it with another U.S. Government-owned transportation system.

Which means the U.S. Government will rely on the U.S. aerospace sector to take care of it's needs - something that the U.S. aerospace sector should be more than capable of doing using their own transportation systems.

I completely agree -- a replacement government HLV would not be sufficiently better than SLS to justify starting over. The question is the details of what to buy and how. Exploration hardware is quantized so NASA needs some mass and volume specifications to design to. If NASA designs to a single launch vehicle NASA won't benefit from competition. So what launchers should NASA design for? (Or really, what specifications?)
« Last Edit: 11/28/2016 04:03 am by deltaV »

Offline MATTBLAK

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Re: What to replace SLS with if it's canceled
« Reply #9 on: 11/28/2016 04:11 am »
Orion can/would make an excellent Cislunar space 'Mothership'. Heh - rather like 'Apollo on Steroids'. It would need significant modifications for Mars or deep beyond Earth space - more capable heatshield, more radiation shielding for the crew and probably more propellants. Dragon 3.0 - or one step beyond 'Red Dragon' - could make a good high-speed Earth Return Vehicle because of it's PICA-X heatshield. But for use as a deep space command ship or command & control module; it would likely need an Apollo-like Service Module, or at least a 'propulsion pallet' mounted within the 'Trunk' of the Dragon.
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Offline TrevorMonty

Re: What to replace SLS with if it's canceled
« Reply #10 on: 11/28/2016 08:13 am »
Canceling SLS would mean canceling Orion.  There is no replacement.

There are four commercial super-heavy US launch vehicles under development:
-Vulcan Heavy
-New Glenn
-Falcon Heavy
-ITS

Wikipedia says Orion + Service Module is about 25 tonnes and 5m diameter. That should be well within the capabilities of all four launchers unless there's a problematic detail such as launch vibrations. Several of those launch vehicles have a lot of development left but Falcon Heavy is almost ready. Why do you say that canceling SLS implies canceling Orion?

Orion was originally a Moon capsule and AFAICT would do OK at that role. Orion doesn't seem very useful however for the Mars program of record. Therefore my two cents on Orion is we should cancel it if we continue with the Mars destination but keep Orion if we switch to the Moon.

It appears that the first three vehicles have similar performance: they’ll all be able to send about 20 tonnes to GTO. (Sources: https://twitter.com/torybruno/status/595628488410963970, http://forum.nasaspaceflight.com/index.php?topic=41146.msg1589576#msg1589576, http://www.spacex.com/falcon-heavy.) It seems unlikely that all three will get built but ISTM at least two vehicles of this class will be, especially if NASA throws a little funding and demand at them. New Glenn and Falcon Heavy seem like the most likely of the four to actually be built so maybe NASA should baseline them? Volume-wise anything that Falcon Heavy can launch New Glenn presumably can too (because of its almost 2x diameter). Which of the two is limiting mass-wise probably depends on target orbit, reusability choices, and whether Falcon Heavy gets cross-feed.

If the U.S. Government doesn't have enough demand to merit owning and operating their own HLV, then there is no need to replace it with another U.S. Government-owned transportation system.

Which means the U.S. Government will rely on the U.S. aerospace sector to take care of it's needs - something that the U.S. aerospace sector should be more than capable of doing using their own transportation systems.

I completely agree -- a replacement government HLV would not be sufficiently better than SLS to justify starting over. The question is the details of what to buy and how. Exploration hardware is quantized so NASA needs some mass and volume specifications to design to. If NASA designs to a single launch vehicle NASA won't benefit from competition. So what launchers should NASA design for? (Or really, what specifications?)
The only two LVs capable of delivering Orion to BLEO would be SLS and 2x Vulcan (distributed launch). With FH and NG it would just be a very expensive LEO taxi.

Offline guckyfan

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Re: What to replace SLS with if it's canceled
« Reply #11 on: 11/28/2016 08:21 am »
Orion can/would make an excellent Cislunar space 'Mothership'. Heh - rather like 'Apollo on Steroids'.

To me it does not look like Apollo on steroids. More like an aged overweight Apollo.

SLS might have some reason to exist. Orion does not.

Offline Steven Pietrobon

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Re: What to replace SLS with if it's canceled
« Reply #12 on: 11/28/2016 08:50 am »
I would replace SLS and Orion with modified versions of Falcon Heavy and Dragon 2. The modified FH would strap together three Falcon 9 first stage cores (the cores don't separate, they land together). The second stage would strap together three Falcon 9 second stages. A third stage would add another Falcon 9 second stage on top. This should give enough performance to put at least 15 t in LLO. The Dragon 2 would be modified to have a storable service module for return to Earth from LLO. A new Lunar Module would be sent to LLO on another FH prior to the Dragon 2.
« Last Edit: 11/28/2016 08:55 am by Steven Pietrobon »
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Offline MATTBLAK

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Re: What to replace SLS with if it's canceled
« Reply #13 on: 11/28/2016 09:21 am »
Orion can/would make an excellent Cislunar space 'Mothership'. Heh - rather like 'Apollo on Steroids'.

To me it does not look like Apollo on steroids. More like an aged overweight Apollo.

SLS might have some reason to exist. Orion does not.
Some would claim the reverse...
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Offline john smith 19

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Re: What to replace SLS with if it's canceled
« Reply #14 on: 11/28/2016 10:13 am »
There is no need to cancel Orion as it could be launched with less powerful launchers.
True
Quote
And actually cancelling SLS would free up more money to keep it.

NASA does not work that way. Congress voted the money for SLS specifically. If SLS goes away odds on bet the money goes with it.

Quote
But assuming we are actually serious about going to mars, where the money needs to go is all of the payloads that are not being developed right now that will be needed for that.
True. Even James Webb is now slated for Ariane 5. Once you know 90% of any Mars mission will be propellant and you know propellant is the easiest commodity to sub divide justifying a massive launcher is quite difficult.
Quote
The path we are on right now will see SLS completed with nothing useful for it to launch.
True.
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Offline MATTBLAK

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Re: What to replace SLS with if it's canceled
« Reply #15 on: 11/28/2016 10:38 am »
Building the smaller than Mir-sized Lunar Gateway Station(?) would give 3 out of 4 launches something to do. Beyond that; new RS-25E engines are required to be built. How many SLS launches will there be before all the old steel SRB segments are used up?
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Offline muomega0

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Re: What to replace SLS with if it's canceled
« Reply #16 on: 11/28/2016 10:42 am »
So what launchers should NASA design for? (Or really, what specifications?)
NASA plans on adopting a LV independent architecture to reduce costs for both science and HSF missions and technology demonstrations, so sizing should be based on payloads for DOD, commercial as well as NASA missions.

Simply having 2 LVs that can carry 20mT to LEO is adequate for Mars DRM like missions, hence *NO* HLV nor super HLV (>100mT) required unless the economics dictate otherwise.  NASA has no payloads that cannot be lofted in 20 mT chunks either--fueling on-orbit.    Risk can be taken with reuse launching dirt cheap propellant.

Offline Coastal Ron

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Re: What to replace SLS with if it's canceled
« Reply #17 on: 11/28/2016 01:05 pm »
The only two LVs capable of delivering Orion to BLEO would be SLS and 2x Vulcan (distributed launch). With FH and NG it would just be a very expensive LEO taxi.

Falcon Heavy can lift far more to LEO than Vulcan can, and since "Distributed Launch" is not something exclusive to ULA, but just the coordinated launch of two or more payloads for the same mission, SpaceX (and others) can also use the same technique to assemble in space a more capable spacecraft than what can be lifted by itself from the surface of the Earth.  For far less money than if the SLS were used.

Of course there is an assumption that the Orion is needed in the future, and that has not yet been proven either.  It has a rather limited range of usefulness, and unless there is a national program focused on returning small amounts of government employees to the region of the Moon for short periods of time, the Orion can be replaced with a more modular and upgradeable solution.
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Offline clongton

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Re: What to replace SLS with if it's canceled
« Reply #18 on: 11/28/2016 01:39 pm »
SLS was not kept alive after President Obama cancelled Constellation in order to go to either the moon or to Mars. It was kept alive thru the maneuverings of Senator Shelby to keep jobs funded at MSFC - nothing more. SLS is a launch vehicle with out a reason for living. Its cancellation is a foregone conclusion, not a question. It is only a matter of time.

For all the talk of going to Mars, the unmentioned 800 pound gruella in the room is that there is absolutely no money available to NASA for humans to Mars missions. For all the bravado, for all the public statements, the NASA plans to send Humans to Mars are essentially nothing more than an awful lot of very detailed, highly sophisticated and voluminous power point presentations and short movie clips. SLS was supposed to be Orion's ride to the moon, as part of a program which no longer exists and where NASA no longer wants to go and imo neither does it intend to. Congress has not allocated any funds for a human lunar mission using SLS. Congress will not allocate any funds for a human mission to Mars, which would cost an order of magnitude more than a human lunar mission. Like the fake Ares-I launch, SLS will fly one time I think, and never fly again.

Assuming SLS is cancelled, per the opening post, that will spell the end of a government-owned launch system - forever - and Orion will go with it.

If NASA wants to do something it will put out an RFQ to industry for launch and spacecraft services. Industry will respond with quotes to use either one of its existing launch vehicles or spacecraft or come back with a quote to build a bigger one, depending on the requested mission.

The very long overdue cancellation of SLS will signal the end of an era. There will be no more government-owned launch vehicles and there will be no more government-owned human spacecraft until those spacecraft become highly reusable, like aircraft and ships. No more will the government purchase use-it-once and throw-it-away spacecraft. Industry will provide all contracted launch services going forward on a for-profit basis.

Under the new administration in Washington NASA might be redirected to the moon but if it is it will not be in Orion on an SLS. SpaceX has demonstrated to all but the willfully blind that the way NASA does business is sinfully wasteful and unnecessarily expensive. The new Administration will not allow that to continue. Expect to see an end to cost-plus contracts and a full blown switch to fixed price contracts. IF NASA is sent to the moon again it will be on launch vehicles and in spacecraft obtained from fixed-price service contracts from industry. It will be every bit as mind-blowing as NASA's previous accomplishments but it will also be billions of dollars less expensive and the companies that provide the services will still make handsome profits.

NASA is still capable of doing great things, but from now on it will not be with the use of government-owned launch vehicles and single-use human spacecraft. We are seeing a paradigm shift in the way NASA does business. The first shot will be the cancellation of the obscenely expensive SLS.

And just to head off any thoughts that I am an SLS-hater, I am not. I think SLS is a wonderful launcher. But it costs the taxpayers far, FAR too much money to build, maintain and operate. It - and the entire way of life it represents - is going away.
« Last Edit: 11/28/2016 01:44 pm by clongton »
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Offline TrevorMonty

Re: What to replace SLS with if it's canceled
« Reply #19 on: 11/28/2016 02:07 pm »
I for hope they don't cancel SLS/Orion until there is flying replacement capable of getting crew to DSH. We need the DSH as BLEO destination in near term and eventually as gateway to moon and mars.

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