Author Topic: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014  (Read 156414 times)

Offline RocketmanUS

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #120 on: 10/25/2014 11:31 pm »
I repeat: He specifically said "tankers". He used the word depot only in reference to Mars ISRU.
Did any of you guys actually watch the interview?
Yes tankers.

MCT launched to Earth orbit.
Tankers launched to orbit to fill MCT(s) ( they act as a propellant depot, lower cost ).

I assume crew ( possible supplies ) will be launched later to orbit to the MCT by a much larger MCT designed to launch on the BFR.

?
Do we know yet if the MCT is to return to Earth orbit afte Mars or Earth surface and relaunched?

Online sanman

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #121 on: 10/25/2014 11:39 pm »
Do we know yet if the MCT is to return to Earth orbit afte Mars or Earth surface and relaunched?

LOL, you mean you didn't hear him coolly wisecrack that whether people wanted to hop back on it or not, he wanted those spaceships to be returning from Mars?   ;D

He's a businessman, and not a mere engineer - he wants his damn capital investment back!
Musk puts the "capital" in "capital ships"!  ;)
« Last Edit: 10/25/2014 11:40 pm by sanman »

Offline RocketmanUS

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #122 on: 10/25/2014 11:49 pm »
Do we know yet if the MCT is to return to Earth orbit afte Mars or Earth surface and relaunched?

LOL, you mean you didn't hear him coolly wisecrack that whether people wanted to hop back on it or not, he wanted those spaceships to be returning from Mars?   ;D

He's a businessman, and not a mere engineer - he wants his damn capital investment back!
Musk puts the "capital" in "capital ships"!  ;)
That is back to Earth orbit or the surface of Earth? ( Yes I know it to be returned ).

It would seem to me it would return to Earth orbit as it is fuelled in orbit.


Online sanman

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #124 on: 10/25/2014 11:59 pm »
That is back to Earth orbit or the surface of Earth? ( Yes I know it to be returned ).

It would seem to me it would return to Earth orbit as it is fuelled in orbit.

I dunno - which is the more economical proposition?
You know that Musk is looking at the bottom line in dollars.

Offline QuantumG

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #125 on: 10/26/2014 12:23 am »
.. and ya know, just started transcribing part 5 and I'm already contemplating self harm.

Quote from: Elon Musk
Well, I think any natural resource extraction on Mars would be - the output would be for Mars. It definitely wouldn't make sense to transport Mars stuff 200 million miles back to Earth. Honestly, if you had like crack-cocaine on Mars, in like prepackaged pallets, it still wouldn't make sense to transport it back here. It's be good times for the Martians, but not back here.

That completely contradicts what he said earlier about one-way trips:

Quote from: Elon Musk
I think it ends up being a moot point because you want to bring the spaceship back. These spaceships are expensive, okay, they're hard to build. You can't just leave them there. So whether or not people want to come back or not, is kind of - like, they can just jump on if they want, but we need the spaceship back.

If colonists can just jump on, why can't they pack the return vehicle with goods? If you were on Mars and you had the choice of sending the vehicle back empty, because no-one wanted to leave this week, or with goods that will let you buy stuff on Earth wouldn't you be packing the ship with everything you could find? The cost of transport is essentially zero because the ship was going back anyway. That's exactly the argument he just made for why one-way trips are a moot point, why is it suddenly invalid now that mining is the question?

Of course, everyone just laughs along.. no-one says anything.. because they're all so enthralled. Gag me with a spoon.

Meanwhile, the question asked was what resources would the colonists be digging up for their own use. Elon didn't answer the question, and the questioner's attempt to get him to answer the question asked was rebuffed. Now, where's that hammer, I need to hit myself with something.
« Last Edit: 10/26/2014 12:26 am by QuantumG »
Human spaceflight is basically just LARPing now.

Offline M_Puckett

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #126 on: 10/26/2014 12:24 am »
If you are running a Methane BFR, why not make a stretched tank version of the first stage to use as a reusable SSTO Tanker and somewhat modified as a one-launch ready-made prop depot?

Offline Lars-J

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #127 on: 10/26/2014 12:37 am »

If you are running a Methane BFR, why not make a stretched tank version of the first stage to use as a reusable SSTO Tanker and somewhat modified as a one-launch ready-made prop depot?

Why? Why do you need the entire first stage for that? It seems far easier to make a stretched upper stage (launched partially loaded) that is customized as a tanker. It also saves you the trouble of developing a custom stretched expendable first stage for the purpose.

And if you already have a reusable first stage, why take that step backwards?

Offline Robotbeat

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #128 on: 10/26/2014 12:39 am »
No one uses LNG at room temperature.
Critical temperature is 190K, so no they don't...
Yeah, when they use it, it's no longer liquid. :)
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 Robotbeat

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #129 on: 10/26/2014 12:41 am »

EDIT: The F9 does not use subcooled RP-1. Not sure where I got that. Thanks Jim for correcting me.

I think I've also heared Elon mention that in the past only as an option for increasing F9\FH's payload,
Sorry, I couldn't find it now.
You are not mistaken. He did mention prop densification as a possible performance improvement.
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 Nindalf

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #130 on: 10/26/2014 12:43 am »
Quote from: Elon Musk
Well, I think any natural resource extraction on Mars would be - the output would be for Mars. ... Honestly, if you had like crack-cocaine on Mars, in like prepackaged pallets, it still wouldn't make sense to transport it back here. It's be good times for the Martians, but not back here.

That completely contradicts what he said earlier about one-way trips:

Quote from: Elon Musk
I think it ends up being a moot point because you want to bring the spaceship back.

If colonists can just jump on, why can't they pack the return vehicle with goods?
It's not that you can't, it's that the value of any raw materials will be insignificant next to the value of the trip, and there will be people on Mars who could use them there.  So why would the Earthlings be able and willing to outbid the Martians by the cost of interplanetary transport?

Anyway, think about it: how would you get crack-cocaine on Mars, in prepackaged pallets?  Clearly, they'd have to have been shipped from Earth.  So why would it make sense to ship it back?

I'm also pretty sure he's also saying that the kind of people who will go to Mars will have an unlimited appetite for crack in particular.

Offline RocketmanUS

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #131 on: 10/26/2014 12:50 am »
.. and ya know, just started transcribing part 5 and I'm already contemplating self harm.

Quote from: Elon Musk
Well, I think any natural resource extraction on Mars would be - the output would be for Mars. It definitely wouldn't make sense to transport Mars stuff 200 million miles back to Earth. Honestly, if you had like crack-cocaine on Mars, in like prepackaged pallets, it still wouldn't make sense to transport it back here. It's be good times for the Martians, but not back here.

That completely contradicts what he said earlier about one-way trips:

Quote from: Elon Musk
I think it ends up being a moot point because you want to bring the spaceship back. These spaceships are expensive, okay, they're hard to build. You can't just leave them there. So whether or not people want to come back or not, is kind of - like, they can just jump on if they want, but we need the spaceship back.

If colonists can just jump on, why can't they pack the return vehicle with goods? If you were on Mars and you had the choice of sending the vehicle back empty, because no-one wanted to leave this week, or with goods that will let you buy stuff on Earth wouldn't you be packing the ship with everything you could find? The cost of transport is essentially zero because the ship was going back anyway. That's exactly the argument he just made for why one-way trips are a moot point, why is it suddenly invalid now that mining is the question?

Of course, everyone just laughs along.. no-one says anything.. because they're all so enthralled. Gag me with a spoon.

Meanwhile, the question asked was what resources would the colonists be digging up for their own use. Elon didn't answer the question, and the questioner's attempt to get him to answer the question asked was rebuffed. Now, where's that hammer, I need to hit myself with something.
If they found fossil(s) they would be worth sending back.

What other thing(s) would Mars have that Earth does not that could be worth sending back?

Would the added mass increase the return trip time?

Offline M_Puckett

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #132 on: 10/26/2014 12:50 am »

If you are running a Methane BFR, why not make a stretched tank version of the first stage to use as a reusable SSTO Tanker and somewhat modified as a one-launch ready-made prop depot?

Why? Why do you need the entire first stage for that? It seems far easier to make a stretched upper stage (launched partially loaded) that is customized as a tanker. It also saves you the trouble of developing a custom stretched expendable first stage for the purpose.

And if you already have a reusable first stage, why take that step backwards?

Because what I am proposing for a Tanker would be reusable.

Offline RonM

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #133 on: 10/26/2014 12:59 am »
If colonists can just jump on, why can't they pack the return vehicle with goods? If you were on Mars and you had the choice of sending the vehicle back empty, because no-one wanted to leave this week, or with goods that will let you buy stuff on Earth wouldn't you be packing the ship with everything you could find? The cost of transport is essentially zero because the ship was going back anyway.

That's a good question. There would at least be a demand for samples for scientific research. Scientist would love kilograms or even tons of material for their research. It would help in planning mining and other ISRU.

Offline yg1968

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #134 on: 10/26/2014 01:05 am »
.. and ya know, just started transcribing part 5 and I'm already contemplating self harm.

Quote from: Elon Musk
Well, I think any natural resource extraction on Mars would be - the output would be for Mars. It definitely wouldn't make sense to transport Mars stuff 200 million miles back to Earth. Honestly, if you had like crack-cocaine on Mars, in like prepackaged pallets, it still wouldn't make sense to transport it back here. It's be good times for the Martians, but not back here.

That completely contradicts what he said earlier about one-way trips:

Quote from: Elon Musk
I think it ends up being a moot point because you want to bring the spaceship back. These spaceships are expensive, okay, they're hard to build. You can't just leave them there. So whether or not people want to come back or not, is kind of - like, they can just jump on if they want, but we need the spaceship back.

If colonists can just jump on, why can't they pack the return vehicle with goods? If you were on Mars and you had the choice of sending the vehicle back empty, because no-one wanted to leave this week, or with goods that will let you buy stuff on Earth wouldn't you be packing the ship with everything you could find? The cost of transport is essentially zero because the ship was going back anyway. That's exactly the argument he just made for why one-way trips are a moot point, why is it suddenly invalid now that mining is the question?

Of course, everyone just laughs along.. no-one says anything.. because they're all so enthralled. Gag me with a spoon.

Meanwhile, the question asked was what resources would the colonists be digging up for their own use. Elon didn't answer the question, and the questioner's attempt to get him to answer the question asked was rebuffed. Now, where's that hammer, I need to hit myself with something.

I thought he said that they can jump off if they want.

Offline Hyperion5

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #135 on: 10/26/2014 01:13 am »

If you are running a Methane BFR, why not make a stretched tank version of the first stage to use as a reusable SSTO Tanker and somewhat modified as a one-launch ready-made prop depot?

Why? Why do you need the entire first stage for that? It seems far easier to make a stretched upper stage (launched partially loaded) that is customized as a tanker. It also saves you the trouble of developing a custom stretched expendable first stage for the purpose.

And if you already have a reusable first stage, why take that step backwards?

Because what I am proposing for a Tanker would be reusable.

Alright everyone, just calm down.  You're in luck, as Dmitry Vorontsov has already looked into this.  A 2-stage BFR tanker (with an enlarged 2nd stage acting as the tanker) is both possible and can deliver a substantial payload while remaining fully reusable.  Also fully reusable?  A standard BFR with a "small" propellant tank payload that delivers roughly the same propellant mass to orbit.  Well I guess the rocket's fully reusable. The tank on the other hand is rather less so...

Offline Robotbeat

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #136 on: 10/26/2014 01:13 am »
QuantumG raises a good point. Street prices for cocaine are around $30k-60k/kg (in the same range as gold), whereas aerospace vehicles are around $1k-10k/kg in dry mass. SpaceX will need to hit the lower end of that for MCT to be cost-effective (i.e. ~$2k/kg). Maybe he's thinking of the /wholesale/ price of cocaine? :) That could easily be an order of magnitude cheaper, around the price per dry mass of MCT.
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 yg1968

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #137 on: 10/26/2014 01:24 am »
QuantumG raises a good point. Street prices for cocaine are around $30k-60k/kg (in the same range as gold), whereas aerospace vehicles are around $1k-10k/kg in dry mass. SpaceX will need to hit the lower end of that for MCT to be cost-effective (i.e. ~$2k/kg). Maybe he's thinking of the /wholesale/ price of cocaine? :) That could easily be an order of magnitude cheaper, around the price per dry mass of MCT.

The MCT would come back for the same reasons that trains and planes come back: there are passengers that will want to go in both directions.
« Last Edit: 10/26/2014 01:06 am by yg1968 »

Offline sittingduck

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #138 on: 10/26/2014 01:26 am »
For once I tend not to agree with QuantumG in that I don't believe Elon's two statements were entirely contradictory.

The return trip for a human would presumably require them to cough up dough for another ticket.  Humans on board for the return trip means in-situ check-ups, repairs and re-fills for the ECLSS, martian-made consumables will need to be paid for and loaded and stored back on the ship, the vehicle will need more prop and thus more time and energy to generate that prop in-situ; all of it as uneconomical a decision as shipping crack or printer ink back to Earth. 

Sure you can come back, as long as you pay a price I would expect to be higher than the 'to Mars' trip.  That doesn't change the interplanetary commerce equation.
« Last Edit: 10/26/2014 01:24 am by sittingduck »

Offline RDoc

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Re: Elon Musk-SpaceX Interview at MIT AeroAstro, Oct 2014
« Reply #139 on: 10/26/2014 01:29 am »
Elon's Crack Cocaine crack does raise a serious question though. If the idea is to actually spread humanity off the Earth, I don't see how it would realistically be done if the colony weren't self supporting both physically and economically.

What possible exports could a Mars colony have that could even come close to paying for the on-going expenses, never mind the initial cost? A related question is if it would be possible for a Mars colony to be self-sufficient within a reasonable period and for a reasonable cost? If it's not then the whole exercise is futile.

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