Author Topic: SLS + BFR Tag-Team Mars Mission?  (Read 4460 times)

Offline speedevil

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #40 on: 08/08/2018 09:39 AM »
BFR/BFS is a hundred times less expensive than SLS, and can do far more than SLS.  For Mars missions, BFR/BFS can do the mission, but SLS can't.

SLS really has no place in a Mars architecture.  None.
Not quite a hundred, unless you are assuming pricing of BFS will be significantly under F9.
My own personal guess would be $45M.

Offline kevinof

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #41 on: 08/08/2018 11:16 AM »
Agreed. SLS is more of the same. Just a big launcher that can throw a lot into orbit/moon/mars. BFS is a system that can launch and land big payloads on mars. It's a system that solves the problem of not only getting the stuff to orbit but also getting it down to the surface. that's the big difference and where it makes it very difficult for SLS to contribute anything to BFS missions.


About the only two things I can see a use for with SLS would be to launch two monolithic payloads: a post-ISS space station into LEO, and a Mars habitat based on the same architecture and sent to Mars after being refueled by a BFT. Neither of these are terribly likely without new money on the table.

For everything else, SLS is too big, too small and far, far too expensive. And it will never fly often enough to become 'safe' for human flights.

Offline ChrisWilson68

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #42 on: 08/08/2018 06:53 PM »
If Bush killed STS because of LOC risk, then he wouldn't have picked even more dangerous destinations.

That does not logically follow.

It is perfectly reasonable to kill STS because of a LOC risk that isn't necessary (the same job can be done with lower LOC risk) and at the same time choose more dangerous destinations because you're getting more benefit out of those destinations.

If LOC had anything to do with it, it would be continuing to risk crews at that LOC rate to let them tip their toe in the kiddie pool.

Just because you think it would be logical to continue that risk "to let them tip their toe in the kiddie pool" if they want to go to those destinations doesn't mean others agree with that assessment.  It's wrong to jump from there to saying LOC had nothing to do with the decision.

And we are continuing the COTS program model for crew rotation that currently has a loss of cargo of 1:16 and 1:10.

COTS/CRS and Commercial Crew are different programs with different standards and different procedures.  It's illogical to look at the loss of cargo figures for COTS/CRS and assume that says anything about Commercial Crew.

Offline ChrisWilson68

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #43 on: 08/08/2018 06:59 PM »
BFR/BFS is a hundred times less expensive than SLS, and can do far more than SLS.  For Mars missions, BFR/BFS can do the mission, but SLS can't.

SLS really has no place in a Mars architecture.  None.
Not quite a hundred, unless you are assuming pricing of BFS will be significantly under F9.
My own personal guess would be $45M.

I actually do think it will be significantly under F9, because of full, rapid reuse and volume of launches.

If BFR/BFS is engaged in a Mars campaign, the marginal cost of another BFR launch (as opposed to adding an SLS launch) should be less than $10 million.

Anyway, even if those figures are off and it's $45M, I'm sure you agree that my point stands about it being far less expensive than SLS.

Online Lar

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #44 on: 08/09/2018 09:30 PM »
Asking how you can design a system to use SLS and BFR together in a Mars architecture is like asking how you can design a system that uses a horse and a gas-powered care together for personal transportation.
This is actually done all the time. The horse rides in a trailer to get to the final destination, where it's unloaded and allowed to pull a cart, or do dressage, or whatever... then at the end it's loaded again and taken home.

So this brought a vision of a BFS chomper taking an SLS upper stage (or an Orion with NASA astros on board) to Mars. And back. Silly vision...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Patchouli

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #45 on: 08/10/2018 12:35 AM »
If I were to use SLS with BFR I'd mostly use SLS to launch Orion with the crew since it has a LAS and over sized items on Block II with the 10 meter fairing.

Then use BFR to carry up all propellant and consumables for the mission as well as any parts that are under 8.4M x 16M.

« Last Edit: 08/10/2018 12:37 AM by Patchouli »

Offline speedevil

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #46 on: 08/10/2018 09:54 AM »
If I were to use SLS with BFR I'd mostly use SLS to launch Orion with the crew since it has a LAS and over sized items on Block II with the 10 meter fairing.

Then use BFR to carry up all propellant and consumables for the mission as well as any parts that are under 8.4M x 16M.
This is a starting price of three billion dollars or so, for the SLS-related components of the mission.

This is in the realm that several dozen test flights of BFS could be budgeted for crew launch assurance (neglecting the fact that F9/dragon can launch them). And it would somewhat surprise me if a slightly stretched second stage for BFR would not be noticably cheaper than one SLS launch.

Once you get into arguments about diameters of 10% making a meaningful difference for a payload that has not been designed yet, for a mission that has not been designed yet, that override a launch cost difference of tens of times, you might as well say 'It can only fly on launchers with the initials SLS'.

There are sort-of-reasonable reasons why 10m might be preferred over 5.4m, but 10 over 8.5 has almost no argument.

Offline Chasm

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #47 on: 08/10/2018 12:29 PM »
Size of a monolithic payload is the only meaningful advantage SLS has in this discussion over BFR. (As currently designed.)

If you allow LEO refueling or payloads assembly SLS is too expensive and unreliable today. No BFR needed to beat it. No F9 either.

Offline speedevil

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #48 on: 08/10/2018 05:08 PM »
Size of a monolithic payload is the only meaningful advantage SLS has in this discussion over BFR. (As currently designed.)r.
Perhaps more energy for very small payloads to very high insertion velocities.
But again, refuelling robs this.

Offline Swedish chef

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #49 on: 08/13/2018 10:37 PM »
One way to force cooperation is by sending the kilopower reactor on SLS to power the BFR ships that will make fuel for the return trip. Here one could argue SpaceX already have the power source figured out, or perhaps why not sending the kilopower reactor on BFR, but in an theoretical situation where in NASA and SpaceX must cooperate one could assume politicians could make life hard for SpaceX unless they cooperate. That and some carrots in the form of funding for SpaceX ought to do it.

So on the plus side.
SLS is needed for helping SpaceX make fuel on Mars.
Nasa is needed for its technological expertise
SpaceX is needed because private company

All could be made possible by a couple of politicians in Washington, so no logic needed just political will.

Offline TomH

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #50 on: 08/14/2018 03:26 AM »
This whole premise is silly, and the posts of late even moreso. IMHO, the thing has run its course and I move the thread be locked.

Offline speedevil

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #51 on: 08/14/2018 10:02 AM »
One way to force cooperation is by sending the kilopower reactor on SLS to power the BFR ships that will make fuel for the return trip.
<snip>
All could be made possible by a couple of politicians in Washington, so no logic needed just political will.
Kilopower (the 10kWe variant) provides around one fiftieth of the power required for making fuel.

edit: This was an attempt to point out the problems with the idea, not make it a meaningful suggestion as to a mission design.
https://forum.nasaspaceflight.com/index.php?topic=45477.msg1810512 I note.
One BFS worth of commercially available solar panels and batteries can provide 500kW continuously.
« Last Edit: 08/14/2018 12:47 PM by speedevil »

Offline A_M_Swallow

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #52 on: 08/14/2018 12:12 PM »
One way to force cooperation is by sending the kilopower reactor on SLS to power the BFR ships that will make fuel for the return trip.
<snip>
All could be made possible by a couple of politicians in Washington, so no logic needed just political will.
Kilopower (the 10kWe variant) provides around one fiftieth of the power required for making fuel.


To lift 50 off 10kWe Kilopower reactors to Mars a large rocket will be needed. That much U235 will need armed guards when being moved around the USA. The US Government may decide to directly control the whole process. The SLS is the Government's big launch vehicle. The rest can go via commercial vehicles like the BFR.

Offline kevinof

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #53 on: 08/14/2018 12:37 PM »
SLS may be able to lift that much but it can't land it on Mars.

One way to force cooperation is by sending the kilopower reactor on SLS to power the BFR ships that will make fuel for the return trip.
<snip>
All could be made possible by a couple of politicians in Washington, so no logic needed just political will.
Kilopower (the 10kWe variant) provides around one fiftieth of the power required for making fuel.


To lift 50 off 10kWe Kilopower reactors to Mars a large rocket will be needed. That much U235 will need armed guards when being moved around the USA. The US Government may decide to directly control the whole process. The SLS is the Government's big launch vehicle. The rest can go via commercial vehicles like the BFR.

Offline A_M_Swallow

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Re: SLS + BFR Tag-Team Mars Mission?
« Reply #54 on: 08/14/2018 12:41 PM »
SLS may be able to lift that much but it can't land it on Mars.

One way to force cooperation is by sending the kilopower reactor on SLS to power the BFR ships that will make fuel for the return trip.
<snip>
All could be made possible by a couple of politicians in Washington, so no logic needed just political will.
Kilopower (the 10kWe variant) provides around one fiftieth of the power required for making fuel.


To lift 50 off 10kWe Kilopower reactors to Mars a large rocket will be needed. That much U235 will need armed guards when being moved around the USA. The US Government may decide to directly control the whole process. The SLS is the Government's big launch vehicle. The rest can go via commercial vehicles like the BFR.

That just means that "the rest" includes a Mars lander.

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