Author Topic: SLS General Discussion Thread 2  (Read 407762 times)

Online Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 16743
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 5455
  • Likes Given: 680
Re: SLS General Discussion Thread 2
« Reply #1580 on: 05/18/2018 06:26 AM »
Quote
NASA replied: Now that the SLS design has matured and the program has more data as a result of progress with hardware manufacturing and testing, our current analysis shows the Block 1 configuration of SLS can deliver an estimated mass of 95 metric tons (209,439 pounds) to low-Earth orbit based on a 200 by 200-kilometer orbit with a 28.5 degree inclination, which is a commonly used orbit in the industry for estimating performance.

Here's the SLS users guide. Unfortunately, Block I performance is not listed. Block IB can put a minimum mass of 94.0 t into a 463 km orbit. Future upgrades increase this to 100.7 t. Block II is 108.3 t. Extrapolating to 200 km, I get 97.7 t, 104.7 t and 112.3 t. I don't see how Block I can get anywhere near 95 t with iCPS using a single RL-10 engine. We also see that Block II doesn't get anywhere near 130 t payload to LEO.

https://ntrs.nasa.gov/search.jsp?R=20170005323
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Online theinternetftw

  • Full Member
  • *
  • Posts: 182
    • www.theinternetftw.com
  • Liked: 424
  • Likes Given: 236
Re: SLS General Discussion Thread 2
« Reply #1581 on: 06/05/2018 06:00 PM »
On performance, here's a relevant slide from the LOP-G All-Hands Presentation.  Block 1 is 26 tonnes to TLI.  Block 1B, 34-40 tonnes.

Online jpo234

  • Full Member
  • ****
  • Posts: 1065
  • Liked: 944
  • Likes Given: 143
Re: SLS General Discussion Thread 2
« Reply #1582 on: 06/07/2018 04:10 PM »
http://spacenews.com/bridenstine-emphasizes-partnerships-with-industry-to-achieve-nasa-goals/

Quote
The SLS, he argued, offered a capability right now that no one else has, and so we want to deliver it. However, he said hed be open to revisiting that should commercial vehicles with similar capabilities enter service in the future. If there comes a day when someone else can deliver that, then we need to think differently. Its always evolving.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline UltraViolet9

  • Full Member
  • *
  • Posts: 136
  • Undisclosed
  • Liked: 181
  • Likes Given: 18
Re: SLS General Discussion Thread 2
« Reply #1583 on: 06/07/2018 05:34 PM »
http://spacenews.com/bridenstine-emphasizes-partnerships-with-industry-to-achieve-nasa-goals/

Quote
The SLS, he argued, offered a capability right now that no one else has, and so we want to deliver it. However, he said hed be open to revisiting that should commercial vehicles with similar capabilities enter service in the future. If there comes a day when someone else can deliver that, then we need to think differently. Its always evolving.

It's been disappointing to see this Administration and this new Administrator give into and not challenge the politics surrounding SLS/Orion.

The position that SLS offers a "capability right now" is bizarro-world from schedule and technical standpoints.  SLS is still years from first launch with no clear path to a stable, operational capability.  And even if SLS was launching, it's payload delivered over time, not per launch, that counts most for supporting exploration architectures once past 40-50t.   The SLS launch rate is so incompetent that it falls woefully short of a NASA Mars DRM and couldn't even maintain the Apollo lunar campaign.

And the position that SLS offers a "capability... no one else has" is blindingly shortsighted from a national policy/national good standpoint.  The US has three domestic launch providers (BO, SX, ULA) either offering or pursuing five different HLVs (NG, NA, FH, BFR/BFS, VHC).  This is a capability that NASA does not need to invest limited budget and human capital on internally.

To shape the future, you have to change the present.  NASA's human space flight enterprise should be shaping the future of US human space exploration capabilities.  Instead, under this Administration and Administrator, NASA will continue to compete very poorly in the ETO space until finally forced by private sector investments to abandon yet more years and billions of taxpayer dollars sunk into SLS.  This is a colossal waste and an enormous missed opportunity.

Offline AncientU

  • Senior Member
  • *****
  • Posts: 6234
  • Liked: 4057
  • Likes Given: 5570
Re: SLS General Discussion Thread 2
« Reply #1584 on: 06/07/2018 09:20 PM »
JB would have never set foot in Administrator's office if he had outright said that SLS wasn't needed or viable.  What he is doing is to set stage for a comparison of vehicles on the launch pad, and selecting one (or more) that provides best performance for the exploration program.  At the same time, he is rolling out tasks for Lunar landers that will be purely commercial; this gets a process rolling. 

This is not dramatic change, but better IMO than former Administrator who said he didn't like the idea of commercial big rockets, and never failed to extol the SLS/Orion-based #JourneytoMars.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline Khadgars

  • Full Member
  • ****
  • Posts: 1009
  • Long Beach, California
  • Liked: 207
  • Likes Given: 602
Re: SLS General Discussion Thread 2
« Reply #1585 on: 06/08/2018 04:25 PM »
SLS will continue and likely fly within the next 24 months.  Nothing currently out there matches its capability, so why do you think NASA would suddenly cancel it now?

I agree, soon as BFR becomes operational, everything currently flying or in-work become obsolete over night but its unreasonable to think NASA should cancel its POR before BFR is a proven entity.  IMO, we're likely at least a decade away from that.
« Last Edit: 06/08/2018 04:39 PM by Khadgars »

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32428
  • Cape Canaveral Spaceport
  • Liked: 11167
  • Likes Given: 331
Re: SLS General Discussion Thread 2
« Reply #1586 on: 06/08/2018 04:49 PM »
SLS will continue and likely fly within the next 24 months.  Nothing currently out there matches its capability, so why do you think NASA would suddenly cancel it now?


It is not flying in 2 years and NASA really doesn't have anything to fly on it.

Offline Coastal Ron

  • Senior Member
  • *****
  • Posts: 4211
  • I live... along the coast
  • Liked: 2869
  • Likes Given: 3713
Re: SLS General Discussion Thread 2
« Reply #1587 on: 06/08/2018 06:11 PM »
SLS will continue and likely fly within the next 24 months.

The development of the SLS sure seems likely to continue, but assuming the first SLS flight won't slip during the next two years is highly optimistic, and goes against the trends for major NASA programs.

Quote
Nothing currently out there matches its capability...

Remember the SLS was not designed to support any known payloads or programs back in 2010 when Congress told NASA to build it. And so far there are no fully-funded programs that require it's unique capabilities (Europa Clipper can use alternate launchers).

So as of today there are no specific requirements that the SLS satisfies. Of course it COULD be used for many payloads, because it is a general purpose transportation system, but as of today you can't say that no other rocket can match it's capabilities because there are no programs or payloads that NEED it's capabilities.

Quote
...so why do you think NASA would suddenly cancel it now?

The organization "NASA" did not ask for the SLS, and has no power to cancel it. Only Congress can cancel the SLS.

Quote
I agree, soon as BFR becomes operational, everything currently flying or in-work become obsolete over night but its unreasonable to think NASA should cancel its POR before BFR is a proven entity.

The SLS is not yet a proven entity, so I'd be careful with using that logic to justify the SLS.

Regardless, as of today the U.S. Government has no need for any kind of HLV. And by "no need" I mean that there are no fully funded programs or payloads that require the long-term use of an HLV, and Congress has had 7 years to fund such a program since the start of the SLS program, so one has to wonder why they haven't?

Quote
IMO, we're likely at least a decade away from that.

Based on how quickly NASA can build and certify HSF hardware (18 years for Orion), it's unlikely that the SLS will be needed in the next 10 years anyways.
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 clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10595
  • Connecticut
    • Direct Launcher
  • Liked: 2699
  • Likes Given: 1004
Re: SLS General Discussion Thread 2
« Reply #1588 on: 06/08/2018 08:32 PM »
It's been disappointing to see this Administration and this new Administrator give into and not challenge the politics surrounding SLS/Orion.
Not challenging the politics surrounding SLS/Orion was likely a condition of one or two confirmation votes.
« Last Edit: 06/08/2018 08:33 PM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Online spacenut

  • Senior Member
  • *****
  • Posts: 2402
  • East Alabama
  • Liked: 404
  • Likes Given: 235
Re: SLS General Discussion Thread 2
« Reply #1589 on: 06/09/2018 12:48 AM »
I do not see a challenge to SLS.  It is wanted by senators from both parties in states where it is made. 

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10595
  • Connecticut
    • Direct Launcher
  • Liked: 2699
  • Likes Given: 1004
Re: SLS General Discussion Thread 2
« Reply #1590 on: 06/11/2018 04:17 PM »
I do not see a challenge to SLS.  It is wanted by senators from both parties in states where it is made. 

Of course. That's it's entire justification for existence; good-paying jobs back home buys re-election votes in November. THAT is what the support is about - in its entirety.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline butters

  • Full Member
  • ****
  • Posts: 1771
  • Liked: 390
  • Likes Given: 141
Re: SLS General Discussion Thread 2
« Reply #1591 on: 06/12/2018 12:22 AM »

Offline Proponent

  • Senior Member
  • *****
  • Posts: 5539
  • Liked: 1068
  • Likes Given: 671
Re: SLS General Discussion Thread 2
« Reply #1592 on: 06/12/2018 01:34 AM »
According to his NASA bio, Todd May earned his bachelor's degree in 1990, which likely makes him quite young by retiriee standards.  So I'd guess he's leaving NASA but not truly retiring.  Seems a little odd.
« Last Edit: 06/12/2018 01:34 AM by Proponent »

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10595
  • Connecticut
    • Direct Launcher
  • Liked: 2699
  • Likes Given: 1004
Re: SLS General Discussion Thread 2
« Reply #1593 on: 06/13/2018 01:03 PM »
According to his NASA bio, Todd May earned his bachelor's degree in 1990, which likely makes him quite young by retiree standards.  So I'd guess he's leaving NASA but not truly retiring.  Seems a little odd.

Why? It's not like people don't retire from one job when they are able to (permanent income) and accept an offer from someone else. I personally know people that have done that, a few of them twice. Unless something more comes out it doesn't seem odd to me at all.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Proponent

  • Senior Member
  • *****
  • Posts: 5539
  • Liked: 1068
  • Likes Given: 671
Re: SLS General Discussion Thread 2
« Reply #1594 on: 06/13/2018 02:58 PM »
I would tend to agree, except that if that's the path Todd May is following then I would have expected an announcement of where he is going.

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10595
  • Connecticut
    • Direct Launcher
  • Liked: 2699
  • Likes Given: 1004
Re: SLS General Discussion Thread 2
« Reply #1595 on: 06/13/2018 10:20 PM »
I would tend to agree, except that if that's the path Todd May is following then I would have expected an announcement of where he is going.

They would have said where only if he told them. Assuming that's his path he may have chosen, as many do, to just not say. "I'm retiring on such and such a date". The only thing he *has* to say is when his "retirement" starts.

I personally know people who retired because they wanted to do something else but hadn't picked a new path yet. So they retired, just because they could, and just relaxed for a while. He's a young man with lots of time ahead of him. Retirement doesn't always mean "I quit working". It can mean anything he wants it to mean and he doesn't owe anyone any explanation at all.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Online spacenut

  • Senior Member
  • *****
  • Posts: 2402
  • East Alabama
  • Liked: 404
  • Likes Given: 235
Re: SLS General Discussion Thread 2
« Reply #1596 on: 06/14/2018 01:00 PM »
Since SpaceX is going to do refueling in LEO for BFR.  IF, another big IF, they develop refueling the second stage in orbit, would say a 40 ton payload launched on FH, then refuel the second stage.  Can this match TMI with SLS block II?  If so, then FH alone with refueling would probably be cheaper than SLS.  At that point would that kill SLS?  Or if New Glen gets going and could do refueling of their hydrolox second stage?  How about Vulcan w/ACES and refueling?  Seems to me refueling in LEO is going to be the way to go.  More vendors, more counties involved to, by using smaller launch vehicles to deliver fuel.  More launches = lower costs for all.  Why isn't NASA working on this instead?

Offline rst

  • Full Member
  • ***
  • Posts: 324
  • Liked: 105
  • Likes Given: 0
Re: SLS General Discussion Thread 2
« Reply #1597 on: 06/14/2018 01:50 PM »
Since SpaceX is going to do refueling in LEO for BFR.  IF, another big IF, they develop refueling the second stage in orbit, would say a 40 ton payload launched on FH, then refuel the second stage.  Can this match TMI with SLS block II?  If so, then FH alone with refueling would probably be cheaper than SLS.  At that point would that kill SLS?  Or if New Glen gets going and could do refueling of their hydrolox second stage?  How about Vulcan w/ACES and refueling?  Seems to me refueling in LEO is going to be the way to go.  More vendors, more counties involved to, by using smaller launch vehicles to deliver fuel.  More launches = lower costs for all.  Why isn't NASA working on this instead?

Second-stage refueling for SLS-class payloads is ULA's plan for Vulcan/ACES, though timelines on that are even iffier than they are for SLS.  Very unlikely that SpaceX would do anything similar with Falcon 9, though.  F9 S2 modifications to support in-orbit refuelling and long-endurance operations would not be small, and the engineers you'd need to do them have their hands full trying to get BFR off the ground.

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10595
  • Connecticut
    • Direct Launcher
  • Liked: 2699
  • Likes Given: 1004
Re: SLS General Discussion Thread 2
« Reply #1598 on: 06/14/2018 03:16 PM »
At that point would that kill SLS?

SLS long ago stopped being about space. It's about jobs back in the home states. So no that will not kill SLS.
Congress will continue to fund this jobs program until it no longer makes sense on the homefront to fund this instead of something else. At that point the funding will transition to the something else.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline kraisee

  • Expert
  • Senior Member
  • *****
  • Posts: 10483
  • Liked: 415
  • Likes Given: 19
Re: SLS General Discussion Thread 2
« Reply #1599 on: 06/14/2018 11:15 PM »
At that point would that kill SLS?

SLS long ago stopped being about space. It's about jobs back in the home states. So no that will not kill SLS.
Congress will continue to fund this jobs program until it no longer makes sense on the homefront to fund this instead of something else. At that point the funding will transition to the something else.

I hope someone within the agency is already working on a plan to transition the workforce into this particular vacuum when it happens.

As we both know all too well (!) there is a whole range of additional projects that could be used to keep all the same funds flowing to the right places and all the same people working hard.   All it will take (!) is to get the political figures to accept the new direction.   I'd love to work on such a thing, but the politics just gets my blood boiling a little too much, and I think it would be wise to pass on the middle aged heart attack :)

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Tags: