Author Topic: Could SLS work for a Mars Direct architecture?  (Read 12215 times)

Online Robotbeat

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Re: Could SLS work for a Mars Direct architecture?
« Reply #40 on: 01/27/2017 06:58 PM »
Oh, also New Glenn should have no problem with an 8m fairing.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Archibald

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Re: Could SLS work for a Mars Direct architecture?
« Reply #41 on: 03/23/2018 11:08 AM »
In your opinion.  Oddly enough, I don't know of any study that supports this.  Do you know of a Mars mission study in the past 50 years that has used launchers with low Earth payloads of less than 50 tonnes and shown that this is superior to using larger boosters I would be most interested in seeing it.

The disadvantages of heavy lift I see:
- Very high development cost historically.
- Potentially low flight rate leading to high per launch cost.
- Doesn't share fixed cost with existing smaller launch vehicles.

The advantages:
- Bigger rockets are more efficient.
- Unique capability of launching large and heavy payloads.

If you look at past Mars architectures from NASA (the DRMs), the Mars landers have always been very big. Around 100t. The advantage is you only need 2 of them. If you go with smaller but more landers, as the more recent EMC does, you don't need a 100t+ to LEO vehicle. Still, existing launch vehicles aren't enough. With HIAD landers something around 40t-50t and a ~8m diameter fairing is probably the minimum. With mid L/D landers 60t-70t.


Quote
Could SLS work for a Mars Direct architecture?



As a matter of fact, whatever the advantages or disadvantes of HLV, SLS seems to be unstoppable as far as Congress goes, despite the fact that so far it has exactly two missions on its flight manifest - EM-1 and EM-2.

http://planetary.org/blogs/casey-dreier/2018/20180322-fy18-omnibus.html

And it aparently lost Europa Clipper, so no science payloads to boost that anemic flight manifest.

So, dare I say, for all the hate against the SLS and all the (political) flaws in it - I'm quite sure it will fly, and fly pretty well, if only a little.  I'm quite confident NASA can build that rocket pretty well.

So, this said and done, why not use SLS for a Mars Direct shot or crash program, NOT to compete with Musk plan, which are for COLONIZATION, but for EXPLORATION, ahead of it ?

Let Mars-Direct-SLS be Mars' Christopher Colombus, and Musk be the Mayflower !

A case could be make that, as it stands today, SLS is good for nothing... except for Mars Direct, because as said in this thread (including by Zubrin HIMSELF) it is the exact rocket described in the Case for Mars and all the Mars Society meetings of the last 25 years !!!

The irony, the irony !
« Last Edit: 03/23/2018 11:17 AM by Archibald »
... that ackward moment when you realize that Jeff Bezos personal fortune is far above NASA annual budget... 115 billion to 18 billion...

Online spacenut

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Re: Could SLS work for a Mars Direct architecture?
« Reply #42 on: 03/23/2018 11:58 AM »
The capability of SLS is great.  Problem is the cost.  It is just not cost effective, in comparison to new rockets coming on line.  Even existing rockets with in space assembly can get you to Mars.  Seems like if NASA were to design a Mars transfer ship, a lander, and the ability to return, then break it all down into 20 ton components (existing launchers), or even 40 ton components (FH and NG, and maybe a Vulcan heavy), Mars can be done right away.  Use existing launchers, and keep multiple manufacturers busy in various states to build the ship, (like Nautilus-X), the money would be better spent and we would already be on our way.   

Offline Russel

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Re: Could SLS work for a Mars Direct architecture?
« Reply #43 on: 03/31/2018 07:37 AM »
Archibald - even for exploration missions a group of Falcon heavys will do the job. And a lot cheaper than SLS.

I too agree that SLS will fly and fly well. But.. (and I'm not going into US politics)

Offline ncb1397

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Re: Could SLS work for a Mars Direct architecture?
« Reply #44 on: 03/31/2018 04:33 PM »
In your opinion.  Oddly enough, I don't know of any study that supports this.  Do you know of a Mars mission study in the past 50 years that has used launchers with low Earth payloads of less than 50 tonnes and shown that this is superior to using larger boosters I would be most interested in seeing it.

The disadvantages of heavy lift I see:
- Very high development cost historically.
- Potentially low flight rate leading to high per launch cost.
- Doesn't share fixed cost with existing smaller launch vehicles.

The advantages:
- Bigger rockets are more efficient.
- Unique capability of launching large and heavy payloads.

If you look at past Mars architectures from NASA (the DRMs), the Mars landers have always been very big. Around 100t. The advantage is you only need 2 of them. If you go with smaller but more landers, as the more recent EMC does, you don't need a 100t+ to LEO vehicle. Still, existing launch vehicles aren't enough. With HIAD landers something around 40t-50t and a ~8m diameter fairing is probably the minimum. With mid L/D landers 60t-70t.


Quote
Could SLS work for a Mars Direct architecture?



As a matter of fact, whatever the advantages or disadvantes of HLV, SLS seems to be unstoppable as far as Congress goes, despite the fact that so far it has exactly two missions on its flight manifest - EM-1 and EM-2.

....

And it aparently lost Europa Clipper, so no science payloads to boost that anemic flight manifest.

And Falcon Heavy has 4 launches on its manifest. Energia launched twice. Saturn V launched 13 times and was extremely successful arguably accomplishing more than 135 Shuttle launches or 52 Falcon launches over the last decade.

As far as Europa Clipper, this is what the 2018 Omnibus bill says:

Quote
That the National Aeronautics and
7 Space Administration shall use the Space Launch System
8 as the launch vehicles for the Jupiter Europa mission,
9 plan for an orbiter launch no later than 2022 and a lander
10 launch no later than 2024, and include in the fiscal year
11 2020 budget the 5-year funding profile necessary to
12 achieve these goals.
http://docs.house.gov/billsthisweek/20180319/BILLS-115SAHR1625-RCP115-66.pdf

So, unless we already have crowned king Trump or NASA has completely gone off the rails, 2 Europa missions are on the manifest and as far as I can tell are 100% funded. Which means Falcon Heavy has 4 launches on the manifest and SLS has 4.
« Last Edit: 03/31/2018 04:33 PM by ncb1397 »

Offline speedevil

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Re: Could SLS work for a Mars Direct architecture?
« Reply #45 on: 03/31/2018 04:58 PM »
So, unless we already have crowned king Trump or NASA has completely gone off the rails, 2 Europa missions are on the manifest and as far as I can tell are 100% funded. Which means Falcon Heavy has 4 launches on the manifest and SLS has 4.

Budgets can contain funding for the next year, they do not bind future budgets, and the funding can be defined differently in future.

It is at least reasonably arguable that BFS also has six launches on the manifest, from a funding source which is at least as secure.