Author Topic: Elon Musk IAC Mars Speech - Sept. 27, 2016 - DISCUSSION THREAD  (Read 441657 times)

Offline ZachF

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Astonished.

You get to ask ONE question to EM, the day of his LIFE speech on Mars.

and what's your pick? toilets?

#speechless.
As a trained biologist I'm not surprised at all. Over two decades ago my teacher on human evolution warned of this kind of "easy life"-facilitated degeneration of human-kind.

was your teacher Mike Judge?  ;)
artist, so take opinions expressed above with a well-rendered grain of salt...
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Offline TripD

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So 100 passengers is for a future (larger) version of the system, it seems.

During the talk, he said the ICT was designed for 100 people, but could probably handle 200.

Can you point to exactly where he said this in the video?

The first mention of it is just after the 25 minute mark.

Edit:  It looks like that was the only mention.
« Last Edit: 09/28/2016 09:39 pm by TripD »

Offline dnavas

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Isn't that [O2 pressurization] what STS did?

Yes, but, there's a helium purge running throughout afaik.  No helium = engine shutdown.  Maybe the hazard is mitigated by running CH4 rather than H2?  Dunno -- way above my expertise.  I'm sure it's possible, I'm not saying it isn't, I am assuming, though, that it will be more difficult to certify correctness and robustness.  And it is definitely not just a size-up of the F9 booster.

Offline NotOnImpact

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One question about the system:

If you are putting 1000 ships in LEO - than that means 4000-5000 fuel launches!.   That is a lot of course - but it seems wasteful.   If we can make methane on Mars, would it be more efficient to make it there and send it back to LEO (with most efficient and slow transit) in advance?   If we could make it on the moon that would be a no-brainer, but not sure if that is possible.   The Earth gravity-well seems like the worse choice.

Offline Jim

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One question about the system:
 If we can make methane on Mars, would it be more efficient to make it there and send it back to LEO (with most efficient and slow transit) in advance?   

No. It would boil off

Offline Cherokee43v6

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Astonished.

You get to ask ONE question to EM, the day of his LIFE speech on Mars.

and what's your pick? toilets?

#speechless.
As a trained biologist I'm not surprised at all. Over two decades ago my teacher on human evolution warned of this kind of "easy life"-facilitated degeneration of human-kind.

was your teacher Mike Judge?  ;)

So we're proving another Sci-Fi prediction true...

H.G. Wells -The Time Machine

I think I'd rather be a Morlock ;)
"I didn't open the can of worms...
        ...I just pointed at it and laughed a little too loudly."

Offline Space Ghost 1962

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Robert Zubrin post on Elon's talk: https://www.facebook.com/robert.zubrin.1/posts/1799839760231952

Overall favourable with this caveat:
Quote
[...]
The key thing I would change is his plan to send the whole trans Mars propulsion system all the way to Mars and back. Doing that means it can only be used once every four years. Instead he should stage off of it just short of Earth escape. Then it would loop around back to aerobrake into Earth orbit in a week, while the payload habitat craft with just a very small propulsion system for landing would fly on to Mars.
[...]

Zubrin makes a good point.
His argument reminds of Jon Goff's argument for small RLV's "pumping" props from ground to LEO in rapid succession.

Will admit that the fast cadence implied in Musk's ITS CONOPs reminds of a revolver/automatic weapon being reloaded ...

But how fast can you effectively "reload"? And what is the max frequency for a "jam" (incident/anomaly) ?

Also think that Zubrin doesn't like Musk's "spacious" approach to transit. Wants the little capsules.

And his motivation is suspect - wanting to see it in his lifetime, boots on Mars. Would like that too, but even better is a multiplanetary species ala Musk - if you're gonna do it, you'll need to build-up a economy, that'll take more than a bunch of little ships.

Also the big "forcing function" might be to get away from overspecialization in space systems to trim weight/bulk, gaining volume of production. So "wasteful" launch architectures might get us out of a moronic bind we are in to advance the applications in space. Perhaps in our skill as aerospace professionals, we've been working against ourselves too long?

Offline Jim

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Yes, it seems to me to be a new class of spaceflight vehicle:  it is a sort of integrated second-stage and spacecraft rolled into one.  Not something we've seen much of (if any) before.


Again, nothing new.  See Agena upper stage and over 300 launches for Corona, Gambit, Midas, Lanyard, Argon, etc

Edit:

Oh and I forgot, Space Shuttle Orbiter.   Over 100 launches and reusable.

Do a little research before making such silly proclamations.
« Last Edit: 09/28/2016 05:39 pm by Jim »

Offline pobermanns

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I flat out don't believe that this thing will land on an unprepared surface without shot-peening its engines to death.
I'm thinking that, until concrete pads can be constructed, one possible option would be to have a rover deploy something like the PSP (pierced steel planking, also known as "Marsden Mattings") landing mats used for helicopters and Harrier jets in forward-deployed locations. However, something lighter in weight than steel, interlocking, and also without the holes in PSP. Maybe this rover and the planking could be delivered by a Red Dragon, provided that the hatch was made large enough for the rover to get out.

This could cover up the sand and pebbles so that they aren't propelled up into the spaceship. Perhaps the same rover could pick up and relocate any medium sized rocks in the chosen LZ.

Offline jstrout

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If you are putting 1000 ships in LEO - than that means 4000-5000 fuel launches!.   That is a lot of course - but it seems wasteful.   If we can make methane on Mars, would it be more efficient to make it there and send it back to LEO (with most efficient and slow transit) in advance?   If we could make it on the moon that would be a no-brainer, but not sure if that is possible.

Certainly you can get the O2 from the Moon; it's abundant there.

Methane is apparently also possible, but would require serious effort — it's present in only trace amounts.

Musk did mention at one point that he considers a lunar fuel depot to be a "future optimization."  I take that as, if somebody builds it and it works out cheaper/better for him, he'll be happy to buy their fuel.

Offline HMXHMX

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People who really did well during the Westward expansion in North America wre the shopkeepers and provisioners.  I can see similar industries starting up around this.   Travel/Hotel people will outfit the spacecraft interiors with modular units just like they do on cruise ships (though not made out of steel obviously).    They will take care of provisioning, entertainment, all that stuff.  Like Norwegian Cruise Lines, adapted for much smaller volumes and lighter weight.   Selling tickets, housing people nearby before the ship spacecraft departs...

This is known as "selling blue jeans to the miners."

Online sanman

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I want to ask again about Musk's comment that spaceship can even travel out to Kuiper Belt and Oort Cloud - surely he only said that just to give a measure of its capabilities. Why would anyone want to do a manned mission out to the Oort Cloud - wouldn't it take your entire lifespan to get there and back? Even Voyager 1 hasn't cleared the Oort Cloud yet.

Kuiper Belt mission might be useful to find some nice ice rocks to hurl at Mars for terraforming purposes, give it more nitrogen in particular. But surely that kind of stuff would be best done as an automated mission - how could people spend so much time out in deep space like that? Such flights could last a decade or more.

Offline Jim

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The on-orbit re-propellanting for the BEO missions allows the spacecraft itself to also fulfill the role that a second stage usually fulfills in the LV design.

No, tanks replace the spacecraft in the refueler.

Offline kch

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So 100 passengers is for a future (larger) version of the system, it seems.

During the talk, he said the ICT was designed for 100 people, but could probably handle 200.

Can you point to exactly where he said this in the video?

https://www.youtube.com/watch?v=H7Uyfqi_TE8?t=1551

That link doesn't work for me, it just starts at the beginning. Can you tell me the time to skip to?

The time (in seconds) is at the end of the link:

t=1551

1551 seconds = 25:51  :)

Offline MikeAtkinson

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Robert Zubrin post on Elon's talk: https://www.facebook.com/robert.zubrin.1/posts/1799839760231952

Overall favourable with this caveat:
Quote
[...]
The key thing I would change is his plan to send the whole trans Mars propulsion system all the way to Mars and back. Doing that means it can only be used once every four years. Instead he should stage off of it just short of Earth escape. Then it would loop around back to aerobrake into Earth orbit in a week, while the payload habitat craft with just a very small propulsion system for landing would fly on to Mars.
[...]

Zubrin makes a good point.

That would get to Mars OK, but it could not get back, if anything the propulsion system to get back from Mars needs to be bigger than that to get to Mars.

There are several ways to allow return journeys, but all of them greatly complicate the architecture and probably increase overall cost.

For Jupiter and the other outer planets and moons, using a second Ship/Tanker as a booster out of LEO would enable faster transits. Even better would be to have both start from a HEO and take advantage of the Oberth effect.

Offline Jim

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Isn't that [O2 pressurization] what STS did?

Yes, but, there's a helium purge running throughout afaik.  No helium = engine shutdown.  Maybe the hazard is mitigated by running CH4 rather than H2?

STS heated O2 for pressurization.  The helium just purged the bearing between the LOX pump and LOX pump turbine. 
« Last Edit: 09/28/2016 05:47 pm by Jim »

Offline alexterrell

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One question about the system:
 If we can make methane on Mars, would it be more efficient to make it there and send it back to LEO (with most efficient and slow transit) in advance?   

No. It would boil off
http://www.green4sea.com/wilhelmsen-sets-new-standard-for-boil-off-rate/

Quote
Wilhelmsen Technical Solutions (WTS) passed a milestone by successfully completing the gas trial for the first LNG carrier built to a Boil Off Rate (BOR) of 0.08% per day.

So about 30% over an 8 month trip.

Why can't boil off be recompressed, chilled, and put back in the the store?

Anyway, I don't think it's practical to ship methane from Mars to Earth Orbit. I would suggest manufacturing it (or kerosene) on Phobos, and using that for a round trip to High Earth Orbit and back to Phobos.

However, Musk is not seemingly interested in Phobos.

Offline Jim

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One question about the system:
 If we can make methane on Mars, would it be more efficient to make it there and send it back to LEO (with most efficient and slow transit) in advance?   

No. It would boil off
http://www.green4sea.com/wilhelmsen-sets-new-standard-for-boil-off-rate/

Quote
Wilhelmsen Technical Solutions (WTS) passed a milestone by successfully completing the gas trial for the first LNG carrier built to a Boil Off Rate (BOR) of 0.08% per day.

So about 30% over an 8 month trip.


That for a terrestrial system and not a mass limited one.

Offline Space Ghost 1962

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Yes, it seems to me to be a new class of spaceflight vehicle:  it is a sort of integrated second-stage and spacecraft rolled into one.  Not something we've seen much of (if any) before.

Oh and I forgot, Space Shuttle Orbiter.   Over 100 launches and reusable.
Would argue it completes the Orbiter's vision (Faget's). In many, many ways.

Musk isn't doing anything new - shouldn't and doesn't need to do. He's attempting to refactor things stultified by lack of vision. Perhaps this might go a bit further.

Offline envy887

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What happens if your exploding stage 1 takes out your engines and gear on the pad or low altitude?
The landing gear likely aren't needed for a soft landing - the Falcon 9 stages did soft water landings and floated for awhile.

An explosion violent enough to take out multiple Stage 2 engines probably breaches the Stage 2 tanks, at which point the whole thing goes kabloomy. I don't see a Stage 2 tank breech during an on-pad booster anomaly being survivable, though it might be survivable if it happens in flight and those spheres inside the tanks hold landing prop.

Getting the upper stage moving away quickly as soon as an anomaly is detected would be critical in any evert. And certainly difficult, but not impossible.
So I guess we are in agreement then that there is only "one" failure mode abort "if" the S2 engines and gear are not damaged and that is "abort to orbit". Any CRS-7 or AMOS-6 type event, for sake of discussion are impossible or "iffy" at best... Inline staging is not fool proof and the Shuttle side mount was not the only risky type architecture which is why Orion, Dragon 2 and CST-100 all have a dedicated LES...
Yes, at least some engines need to be functional, number depending on abort type.
Disagree that the gear need to be intact: soft water landing without gear should be possible.
Disagree that abort to orbit is only option: abort downrange or RTLS should be possible.

Certainly launch is dangerous and every architecture has it's limitations. I don't like the idea of launching without a real LAS and won't until it has 1000's of flights. Actually, I'm wildly speculating if it's possible to use pusher rockets in the chines by the cargo bay to push the crew pressure vessel clear (after separating from the US tanks with shaped charges) and chute it into the ocean. Think it might be.

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