Author Topic: MCT Speculation and Discussion Thread 4  (Read 610284 times)

Offline Paul451

  • Full Member
  • ****
  • Posts: 1368
  • Australia
  • Liked: 675
  • Likes Given: 571
Re: MCT Speculation and Discussion Thread 4
« Reply #2180 on: 06/09/2016 05:08 PM »
On the end of the crane, you'd have a clamshell bucket or orange-peel grabs or something like a blend between the two.

I said a bucket on a cable requires human finesse to control, something that can't be automated yet (certainly not "easily"). You specifically said you weren't talking about that.

and could be enhanced by dragging it with another cable

So now you're describing a dragline, which you specifically said you weren't.

You're shocked at my confusion when you completely contradict yourself?

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2181 on: 06/09/2016 05:42 PM »
On the end of the crane, you'd have a clamshell bucket or orange-peel grabs or something like a blend between the two.

I said a bucket on a cable requires human finesse to control, something that can't be automated yet (certainly not "easily"). You specifically said you weren't talking about that....
I thought you were referring to a dragline. Anyway, I've seen these mechanisms in action. Very little finesse is necessary to grab material if you're not concerned with exactly what spot of dirt you're grabbing or if you're getting a whole bunch of dirt or not. This is not an especially hard problem.
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

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2182 on: 06/09/2016 05:43 PM »
...
and could be enhanced by dragging it with another cable

So now you're describing a dragline, which you specifically said you weren't.

You're shocked at my confusion when you completely contradict yourself?
I WASN'T talking about a dragline, I was simply acknowledging there that you COULD use one.
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

Online Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10110
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6952
  • Likes Given: 4742
Re: MCT Speculation and Discussion Thread 4
« Reply #2183 on: 06/09/2016 05:57 PM »
I've operated a dragline[1]. It's pretty hard to get a good load and raise it successfully. Especially repeatably. So I think it's not exactly something I'd call "very little finesse".

1 - It was a LEGO model, but it was built by someone whose job it is to spec draglines for coal mines and he said the real thing operates the same way. Very finicky in operation, and taking a very deft hand on the controls with situational awareness of exactly what kinds of lumps and irregularities face you.
"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 Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2184 on: 06/09/2016 06:00 PM »
I've operated a dragline[1]. It's pretty hard to get a good load and raise it successfully. Especially repeatably. So I think it's not exactly something I'd call "very little finesse".

1 - It was a LEGO model, but it was built by someone whose job it is to spec draglines for coal mines and he said the real thing operates the same way. Very finicky in operation, and taking a very deft hand on the controls with situational awareness of exactly what kinds of lumps and irregularities face you.
A) Getting a good load is not at all a requirement. We're talking about a very small amount of material, relatively speaking.
B) The dragline comment was an aside, an acknowledgement of a possible improvement. Not my actual point. I was talking about this: https://en.wikipedia.org/wiki/Bucket_(machine_part)#/media/File:Coal_loading_shell_grabs,_Cardiff.jpg
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 lamontagne

  • Full Member
  • ****
  • Posts: 1092
  • Liked: 1549
  • Likes Given: 242
Re: MCT Speculation and Discussion Thread 4
« Reply #2185 on: 06/09/2016 06:26 PM »
I've operated a dragline[1]. It's pretty hard to get a good load and raise it successfully. Especially repeatably. So I think it's not exactly something I'd call "very little finesse".

1 - It was a LEGO model, but it was built by someone whose job it is to spec draglines for coal mines and he said the real thing operates the same way. Very finicky in operation, and taking a very deft hand on the controls with situational awareness of exactly what kinds of lumps and irregularities face you.
A) Getting a good load is not at all a requirement. We're talking about a very small amount of material, relatively speaking.
B) The dragline comment was an aside, an acknowledgement of a possible improvement. Not my actual point. I was talking about this: https://en.wikipedia.org/wiki/Bucket_(machine_part)#/media/File:Coal_loading_shell_grabs,_Cardiff.jpg
A lot will depend on the condition of the soil/regolith.  If it is solidly frozen, rather like permafrost, then shovels and draglines will not be much use, it'll be too tough to penetrate.  If it's loose with boulders or large 'rocks' of sand and ice, then it's a lot simpler.  If it's a cliff face, then it's relatively easy to bore into.  A few kg of well placed explosives might do wonders in loosening up the soil. That's a well known procedure!
Some kind of scrapper tool, rather like an ice rink Zamboni, but tougher, might work in certain conditions as well.  If it's a layer cake of sand and ice, and the sand layer is not solidly frozen, then you might just want to saw out layers of ice. Very site specific is my guess.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2186 on: 06/09/2016 06:51 PM »
Drop a weight on it to break it up. Then scoop up the broken up soil. Could be done very inefficiently and still be acceptable.
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

Online Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10110
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6952
  • Likes Given: 4742
Re: MCT Speculation and Discussion Thread 4
« Reply #2187 on: 06/09/2016 07:02 PM »
Having some trouble with the notion that you can do this "inefficiently" and actually get any useful material before you wear out your equipment.

Those coal loader scoops only work when dropped pretty much straight down. So now you need a boom of some sort to position the scoop where you want it (which you did with a dragline too).

Why are we arguing about this? And why here? I've lost how this is related to the MCT per se. It's related to how to do ISRU, for sure but not MCT design...

"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 RonM

  • Senior Member
  • *****
  • Posts: 2378
  • Atlanta, Georgia USA
  • Liked: 1208
  • Likes Given: 926
Re: MCT Speculation and Discussion Thread 4
« Reply #2188 on: 06/09/2016 07:14 PM »
Well, something will have to be able to prepare propellent for the first crewed MCT, probably a robotic MCT.

One possibility is to use a modified version of a solar still. Making a solar still are one of the things taught in survival training. Instead of digging a hole in the ground, a box can be lowered to the surface. The idea is that solar energy would create enough heat to cause ice to sublimate. The trick would be how to collect the moisture. Should be a lot easier than mechanical systems. Once a crew arrives, an ice mining system can be setup.


Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2189 on: 06/09/2016 07:37 PM »
Having some trouble with the notion that you can do this "inefficiently" and actually get any useful material before you wear out your equipment.
Go back and read the orders of magnitude point I made. We can get just 1/1000th the material that you'd get with typical mining equipment and still have sufficient material. Our intuitions are screaming about stuff that is not relevant at this scale.

Quote
Those coal loader scoops only work when dropped pretty much straight down. So now you need a boom of some sort to position the scoop where you want it (which you did with a dragline too).
Yeah, that's what the crane is for.

Quote
Why are we arguing about this? And why here? I've lost how this is related to the MCT per se. It's related to how to do ISRU, for sure but not MCT design...
Because I threw out the fact that something simple, even something as dumb as a crane, could be used instead of a rover. And the throw of a crane would be enough that it wouldn't even need to move its base to capture enough material. It was a throwaway comment that someone couldn't resist challenging with their intuitions honed on Earth but misled because the intuition is trained with orders of magnitude more throughput requirements.
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

Online envy887

  • Senior Member
  • *****
  • Posts: 4100
  • Liked: 2121
  • Likes Given: 1269
Re: MCT Speculation and Discussion Thread 4
« Reply #2190 on: 06/09/2016 08:33 PM »
...

Also of interest: in a vacuum it gets 92 to 96 % of the performance fully expanded vac nozzle. If the mission requires that last 4-8% of performance, then an extension failure would cause LoM.
...for a LOT of missions, success isn't entirely binary. I can point to several times when RL-10-based upper stages had a significantly early shutdown for one reason or another but the performance was still made up for, perhaps by the payload. This may lead to lower on-orbit fuel, which is annoying and can shorten the life of the payload, but this isn't LoM.

If you think of the nozzle as retractable rather than extendable ( i.e. their purpose is to permit supersonic retropropulsion without blasting the extension bell, rather than to save length), then LoM isn't very likely even if 100% performance is needed.

In this case the nozzles could be extended before committing to launch from either Earth or Mars surface, and would be retracted after transfer injection. With 4 or more engines, landing should still be feasible even if one fails to retract and can't be fixed during transfer.

Offline Paul451

  • Full Member
  • ****
  • Posts: 1368
  • Australia
  • Liked: 675
  • Likes Given: 571
Re: MCT Speculation and Discussion Thread 4
« Reply #2191 on: 06/10/2016 07:26 AM »
Very site specific is my guess.

Most mining/tunnelling/clearing work is. That's why handwaving it as "easily automated" gets my attention.

Existing mining "automation" is limited to already prepared sites, and it isn't automated. The overwhelming majority is merely remotely driven by humans. The few things that people hope to automate are generally things like on-site transport. Moving material between set locations along prepared and marked (robot-friendly) paths.

They are also massively overbuilt, heavy, and still high-maintenance. And the usual engineering rule of thumb is that every time you halve the mass, you drop the work-life by an order of magnitude.

[I recall as a kid, every fortnight or so, having to help Dad change out the hardened steel teeth on the trenching machine. This was for something that spent 90% of its working life digging through clay and clean compacted fill, not mining, hardly a rock in sight.]
« Last Edit: 06/10/2016 07:28 AM by Paul451 »

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2192 on: 06/10/2016 07:30 AM »
It wouldn't be worth automating on Mars if sending people out to do the work were as easy to do as it is on Earth. The required soil could be shoveled manually at sufficient rates. We wouldn't automate such a task, we'd just give them a backhoe or something. The only reason to automate it is because it's on Mars.
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 Paul451

  • Full Member
  • ****
  • Posts: 1368
  • Australia
  • Liked: 675
  • Likes Given: 571
Re: MCT Speculation and Discussion Thread 4
« Reply #2193 on: 06/10/2016 09:12 AM »
For Lar's sake I'll let it drop, but assume my right eye is twitching and my fingers are clawing at the screen.

Offline mme

  • Full Member
  • ****
  • Posts: 1240
  • Santa Barbara, CA, USA, Earth, Solar System, Milky Way Galaxy, Virgo Supercluster
  • Liked: 1515
  • Likes Given: 4096
Re: MCT Speculation and Discussion Thread 4
« Reply #2194 on: 06/10/2016 04:56 PM »
a few more teasers before the september reveal:

https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/

1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...
Bold mine.
Space is not Highlander.  There can, and will, be more than one.

Offline MikeAtkinson

  • Full Member
  • ****
  • Posts: 1748
  • Bracknell, England
  • Liked: 514
  • Likes Given: 65
Re: MCT Speculation and Discussion Thread 4
« Reply #2195 on: 06/10/2016 05:03 PM »
a few more teasers before the september reveal:

https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/

1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...
Bold mine.

That is first fight of MCT to Mars in 2022, which likely means that BFR/BFS first flight would need to be in 2021.

Offline MikeAtkinson

  • Full Member
  • ****
  • Posts: 1748
  • Bracknell, England
  • Liked: 514
  • Likes Given: 65
Re: MCT Speculation and Discussion Thread 4
« Reply #2196 on: 06/10/2016 05:23 PM »
This thread hasn't been updated for a while (so there may be some public details that have been missed), but here's something new:

a few more teasers before the september reveal:

https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/

1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...

This statement was in the timeline of mars missions, so implies MCT to Mars in 2022 and likely first flight of BFR/BFS in 2021.

Also something we already suspected but now have added confirmation:
Quote from: musk
“the first mission wouldn’t have a huge number of people on it because if something goes wrong, we want to risk the fewest number of lives as possible.”

Offline philw1776

  • Full Member
  • ****
  • Posts: 1016
  • Seacoast NH
  • Liked: 608
  • Likes Given: 288
Re: MCT Speculation and Discussion Thread 4
« Reply #2197 on: 06/10/2016 06:01 PM »
a few more teasers before the september reveal:

https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/

1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...
Bold mine.

That is first fight of MCT to Mars in 2022, which likely means that BFR/BFS first flight would need to be in 2021.

"Then in 2022, Musk said he hoped to launch what the company now sometimes refers to as the Mars Colonial Transporter, designed to bring a colony to Mars."

Says to me, first launch of MCT in 2022, NOT specifically TO Mars, just launch.
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 6673
  • Germany
  • Liked: 1732
  • Likes Given: 1693
Re: MCT Speculation and Discussion Thread 4
« Reply #2198 on: 06/10/2016 06:06 PM »
Says to me, first launch of MCT in 2022, NOT specifically TO Mars, just launch.

Not at all. That timetable was explicitly for Mars launches. And first landing on Mars with MCT is an obvious necessity. Not only to install ISRU. They need successful Mars landings with MCT before they can send people.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 28094
  • Minnesota
  • Liked: 7912
  • Likes Given: 5265
Re: MCT Speculation and Discussion Thread 4
« Reply #2199 on: 06/10/2016 06:45 PM »
I think they may be sending significant ISRU equipment in 2020, even before 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

Tags: