Author Topic: MCT Speculation and Discussion Thread 4  (Read 604171 times)

Offline llanitedave

  • Senior Member
  • *****
  • Posts: 2138
  • Nevada Desert
  • Liked: 1315
  • Likes Given: 1545
Re: MCT Speculation and Discussion Thread 4
« Reply #1680 on: 02/16/2016 03:09 PM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf

I'm being flippant when I talk about the passengers/crew wigging out, but this is something crews on nuclear subs have to be carefully screened for. The British still do hot bunking - it's just the junior crew who have to suffer through it. About 1/3 of submariners are discharged for psychological reasons after their first tour. It may be lower (I didn't check the figures) but it's still a terrible psychological toll. Put your average hipster in there and you may find a gibbering mess coming out.

Assuming 18 people can use the same communal space as 6, then 15m^3 looks possible.


I never had to hot bunk on the sub I was on, but some of the crew did.  This was in the mid to late 1970's, in an FBM submarine that was large for its day.  I worked and bunked in the missile compartment, the largest space on the boat, so my conditions were better than most.  But it's true that even there, after a few weeks of submerged patrol, some people did start to wig out, and there were some major confrontations that developed over the most trivial triggering incidents.
"I've just abducted an alien -- now what?"

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28045
  • Minnesota
  • Liked: 7856
  • Likes Given: 5231
Re: MCT Speculation and Discussion Thread 4
« Reply #1681 on: 02/16/2016 03:48 PM »
I don't think they'll be hot-bunking on MCT. But sleeping in shifts (and spending time in personal bunk reading, etc) would still improve space per passenger in the common areas.
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 guckyfan

  • Senior Member
  • *****
  • Posts: 6650
  • Germany
  • Liked: 1721
  • Likes Given: 1665
Re: MCT Speculation and Discussion Thread 4
« Reply #1682 on: 02/16/2016 04:17 PM »
Hot bunking should not even be considered on MCT. In a sub it can work because when not sleeping they have a station to attend to. Passengers on MCT don't. So a private sleeping place is the most volume efficient way. People can sleep, watch a movie, use the computer for entertainment or learning, without taking up space in the communal area.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7317
  • Everyplaceelse
  • Liked: 1071
  • Likes Given: 7181
Re: MCT Speculation and Discussion Thread 4
« Reply #1683 on: 02/16/2016 06:33 PM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf
Assuming 18 people can use the same communal space as 6, then 15m^3 looks possible.
Much more helpful but quite disturbing. I note 2 things.

5 m^3 is the very low end of the range for missions about 3 months.

But more worryingly there is a sense in the 2 reports that this is just a placeholder as there has simply been
been no research in this area to find out what the minimum really is.

BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28045
  • Minnesota
  • Liked: 7856
  • Likes Given: 5231
Re: MCT Speculation and Discussion Thread 4
« Reply #1684 on: 02/16/2016 06:46 PM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf
Assuming 18 people can use the same communal space as 6, then 15m^3 looks possible.
Much more helpful but quite disturbing. I note 2 things.

5 m^3 is the very low end of the range for missions about 3 months.

But more worryingly there is a sense in the 2 reports that this is just a placeholder as there has simply been
been no research in this area to find out what the minimum really is.
1)Yes, you start out looking at the minimum to bound the problem. Obviously, there's not really a maximum.
2) Studies almost always are looking at crews of 3-8, not 50-100. With small crews, rotating sleep schedules don't make much sense as the crew is working together. So most studies would miss some ways that space can be used more effectively.
3) it's wrong to say no research has been done. Reality is that soft sciences often have problems whose solutions are really hard to nail down.
4) There are no doubt countermeasures and techniques that would effect what the minimum space per passenger is. The hard physiological limit is obviously much less than 5m^3 per person, but it's really hard to say for sure what the true psychological minimum is.
5) SpaceX is probably thinking more than 5m^3 per passenger, at least for the first iterations of MCT.
« Last Edit: 02/16/2016 06:49 PM by Robotbeat »
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 The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1071
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 756
  • Likes Given: 627
Re: MCT Speculation and Discussion Thread 4
« Reply #1685 on: 02/16/2016 07:44 PM »

I suspect the average hipster is already a gibbering mess. Putting on in a spaceship will just make him/her gibberouser.

 Excreting indignance is for youtube, not here.

It would be a mistake to assume people are going to walk through the door with the correct mindstate, as everyday life doesn't foster the required mindstate for Mars. People are going to be trained over a number of months, perhaps years at first, for a considerable period of time. The years will  be long before a ticket to mars is as simple as flashing your boarding pass.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7317
  • Everyplaceelse
  • Liked: 1071
  • Likes Given: 7181
Re: MCT Speculation and Discussion Thread 4
« Reply #1686 on: 02/16/2016 11:48 PM »
I never had to hot bunk on the sub I was on, but some of the crew did.  This was in the mid to late 1970's, in an FBM submarine that was large for its day.  I worked and bunked in the missile compartment, the largest space on the boat, so my conditions were better than most.  But it's true that even there, after a few weeks of submerged patrol, some people did start to wig out, and there were some major confrontations that developed over the most trivial triggering incidents.
It's kind of worrying that would happen despite what I presume was fairly extensive screening for the roles.  :(

The worst aspect of this is that in extreme conditions the boat could surface and request help.

An MCT en route may never be out of radio range of Earth but once the first TMI burn begins Mr Newton is in the driving seat. There is no concept of turnaround.   :(
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7317
  • Everyplaceelse
  • Liked: 1071
  • Likes Given: 7181
Re: MCT Speculation and Discussion Thread 4
« Reply #1687 on: 02/16/2016 11:49 PM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf

Much better.

The bottom line of those 2 reports seems to be that that they are recommending just the personal space be somewhere between 7-8 m^3.

Unless this MCT comes with a big blow up section that's going to have a pretty sizeable impact on vehicle size.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28045
  • Minnesota
  • Liked: 7856
  • Likes Given: 5231
Re: MCT Speculation and Discussion Thread 4
« Reply #1688 on: 02/17/2016 12:12 AM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf

Much better.

The bottom line of those 2 reports seems to be that that they are recommending just the personal space be somewhere between 7-8 m^3.
...
...it should be noted that the last report (2015) is referencing ~5m^3 of person space for missions 912 days in duration. That's an order of magnitude greater duration than the MCT's 3 month trip. Also, everything seems quite hand-wavy as to why /exactly/ that much space is needed.

In the 2011 report, most of those problems seem better mitigated by things other than simply having more per-person volume. For instance, sending always two or more MCTs at once (with margin for both) would provide full backup capability without adding extra space required just for backup use. Customizability is something that is also not volume-dependent. Having sufficient mental tasks can be accomplished by providing stimulating training during the transit, including perhaps group projects to prepare for life on Mars. VR headsets could help with mental stimulation, as well as having the entire Netflix catalogue available.

Proper layout of the cabin itself as well as good sleep schedule management (with some freedom to change sleep shift if you want) could help relieve congestion in common areas without needing any more volume per person.

...again, those reports don't at all seem definitive about what exactly is the minimum per-passenger space needed for a short 90-100 day transit.


...and remember also that for the same mass, allocating less volume will improve the radiation protection automatically.
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 kaoru

  • Member
  • Posts: 53
  • Ottawa, ON, Canada
    • Sculpt Science
  • Liked: 34
  • Likes Given: 8
Re: MCT Speculation and Discussion Thread 4
« Reply #1689 on: 02/17/2016 01:07 AM »
After reading the NASA reports/specs for "orbital" modules and reading the posts here, there seems to be a disjoint.  The MCT has to ascend and land which means passengers will need a seat.  Moreover, the MCT will be on Earth and Mars (in the vertical position) therefore orientation is predetermined.  This means that the vertical height will be fixed, most likely 7 feet.  The area (not volume) for a crew/sleep station should the size of a bed and storage.  The bed would articulate into a seat and workstation (aka cubicle).  Think of like a first class seat on a long haul aircraft.  Bed at (simulated) night and cubicle by day.  Not that different from my life if you minus my commute.  :)

Kaoru
« Last Edit: 02/17/2016 01:09 AM by kaoru »

Offline philw1776

  • Full Member
  • ****
  • Posts: 1012
  • Seacoast NH
  • Liked: 608
  • Likes Given: 284
Re: MCT Speculation and Discussion Thread 4
« Reply #1690 on: 02/17/2016 01:08 AM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf

Much better.

The bottom line of those 2 reports seems to be that that they are recommending just the personal space be somewhere between 7-8 m^3.

Unless this MCT comes with a big blow up section that's going to have a pretty sizeable impact on vehicle size.

I don't see that.
Assuming that the MCT or BFS is 15 meters in diameter an 8 meter long passenger section has 1415 m^3 or 14 m^3 per person. 
Alternatively, three ~two meter high decks give 1062 m^3 or 10 m^3 per person.  That's a pretty small length 6 or 8 meters relative to the behemoths people are modeling.
Yes I know that walls and floors are not zero thickness, etc.  The numbers are approximations.
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

Offline Impaler

  • Full Member
  • ****
  • Posts: 1283
  • South Hill, Virgina
  • Liked: 363
  • Likes Given: 0
Re: MCT Speculation and Discussion Thread 4
« Reply #1691 on: 02/17/2016 05:16 AM »
That's an order of magnitude greater duration than the MCT's 3 month trip. Also, everything seems quite hand-wavy as to why /exactly/ that much space is needed.


90 day transit is insanely expensive in propellant, and while it might be possible to do it from LEO at huge cost in propellant.  But the longest leg of the journey is what you need to plan around and that is likely to be the Earth return leg.

Do your remember the discussion we had back on page 39 & 40 when we found that just 100 days Earth return launches from Mars surface would require 8.8 km/s DeltaV and significant aero-braking or propulsive capture at Earth.


Transit times of 120-180 days for Earth return are the range that's actually achievable.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28045
  • Minnesota
  • Liked: 7856
  • Likes Given: 5231
Re: MCT Speculation and Discussion Thread 4
« Reply #1692 on: 02/17/2016 05:34 AM »
You'll have fewer crew for the return journey. Thems the rules or this whole thing doesn't work.
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 Burninate

  • Full Member
  • ****
  • Posts: 1133
  • Liked: 350
  • Likes Given: 72
Re: MCT Speculation and Discussion Thread 4
« Reply #1693 on: 02/17/2016 06:09 AM »
You'll have fewer crew for the return journey. Thems the rules or this whole thing doesn't work.

Why even bother returning the vehicles?  We could just scale up Mars One by a factor of 30?

"But it's necessary for the price to drop to $500k..."

Strong guarantees of a round-trip ticket are necessary to get a million people to pay $500k to go to Mars.

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 6650
  • Germany
  • Liked: 1721
  • Likes Given: 1665
Re: MCT Speculation and Discussion Thread 4
« Reply #1694 on: 02/17/2016 07:49 AM »
Strong guarantees of a round-trip ticket are necessary to get a million people to pay $500k to go to Mars.

Certainly not! It is obvious that a million people, or even 10,000 cannot be brought back. The return guarantee is important early on, not when the colony is established. Or maybe for everyone but not for all.

Offline Lampyridae

  • Veteran
  • Full Member
  • ****
  • Posts: 1659
  • Liked: 76
  • Likes Given: 135
Re: MCT Speculation and Discussion Thread 4
« Reply #1695 on: 02/17/2016 09:13 AM »
Sorry, wrong link.

http://msis.jsc.nasa.gov/sections/section08.htm#Figure 8.6.2.1-1

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2011-217352.pdf

http://ston.jsc.nasa.gov/collections/trs/_techrep/TM-2015-218564.pdf

Much better.

The bottom line of those 2 reports seems to be that that they are recommending just the personal space be somewhere between 7-8 m^3.
...
...it should be noted that the last report (2015) is referencing ~5m^3 of person space for missions 912 days in duration. That's an order of magnitude greater duration than the MCT's 3 month trip. Also, everything seems quite hand-wavy as to why /exactly/ that much space is needed.

In the 2011 report, most of those problems seem better mitigated by things other than simply having more per-person volume. For instance, sending always two or more MCTs at once (with margin for both) would provide full backup capability without adding extra space required just for backup use. Customizability is something that is also not volume-dependent. Having sufficient mental tasks can be accomplished by providing stimulating training during the transit, including perhaps group projects to prepare for life on Mars. VR headsets could help with mental stimulation, as well as having the entire Netflix catalogue available.

Proper layout of the cabin itself as well as good sleep schedule management (with some freedom to change sleep shift if you want) could help relieve congestion in common areas without needing any more volume per person.

...again, those reports don't at all seem definitive about what exactly is the minimum per-passenger space needed for a short 90-100 day transit.


...and remember also that for the same mass, allocating less volume will improve the radiation protection automatically.

The data is based on confinement studies, analogues and historical spaceflight. When we talk of 5m^3 per person, let's not forget that shuttle missions ran to 10m^3 per person. 5m^3 is Apollo CSM+LSM. The SEALAB II clocked in at 17m^3 with 10 people and by all accounts it seemed awful. I think MCTs at these volumes will have to have separate male and female flights, or at least have separate bunkroom & washroom sections according to gender.

https://books.google.co.za/books?hl=en&lr=&id=vEkQFWgN5WsC&oi=fnd&pg=PR9&dq=Groups+under+stress:+Psychological+research+in+SEALAB+II&ots=14xol7gZkQ&sig=D41SgF9xNRd4oI-IHN0MqnQQsM4#v=onepage&q&f=false

http://www.spacearchitect.org/pubs/ICES2008/Abstracts/08ICES-0046.pdf

The references are extensive in the previous docs I linked... worth checking out.
« Last Edit: 02/17/2016 11:24 AM by Lampyridae »
SKYLON... The League of Extraordinary Gentlemen's preferred surface-to-orbit conveyance.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7317
  • Everyplaceelse
  • Liked: 1071
  • Likes Given: 7181
Re: MCT Speculation and Discussion Thread 4
« Reply #1696 on: 02/17/2016 11:44 AM »

90 day transit is insanely expensive in propellant, and while it might be possible to do it from LEO at huge cost in propellant.  But the longest leg of the journey is what you need to plan around and that is likely to be the Earth return leg.

Do your remember the discussion we had back on page 39 & 40 when we found that just 100 days Earth return launches from Mars surface would require 8.8 km/s DeltaV and significant aero-braking or propulsive capture at Earth.
That's huge emphasizing the need to make ECLSS closed loop as much as possible.
Quote
Transit times of 120-180 days for Earth return are the range that's actually achievable.
These are the figures I was thinking about.  Do you happen to have the Delta V to give a 100 day to Mars trip?
That also hint SX might like to make it an uncrewed return, but then how do  you get the crew back for the next one?
« Last Edit: 02/17/2016 11:47 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C Apply So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28045
  • Minnesota
  • Liked: 7856
  • Likes Given: 5231
Re: MCT Speculation and Discussion Thread 4
« Reply #1697 on: 02/17/2016 12:32 PM »
You'll have fewer crew for the return journey. Thems the rules or this whole thing doesn't work.

Why even bother returning the vehicles?  We could just scale up Mars One by a factor of 30?

"But it's necessary for the price to drop to $500k..."

Strong guarantees of a round-trip ticket are necessary to get a million people to pay $500k to go to Mars.
If the crew modules are unloaded for surface habitation, then you can use some of the cargo vehicles. If you're talking evacuating the entire planet, that would take longer than a single synod anyway, an impossible standard if you really believe in establishing a city.
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 philw1776

  • Full Member
  • ****
  • Posts: 1012
  • Seacoast NH
  • Liked: 608
  • Likes Given: 284
Re: MCT Speculation and Discussion Thread 4
« Reply #1698 on: 02/17/2016 01:57 PM »

90 day transit is insanely expensive in propellant, and while it might be possible to do it from LEO at huge cost in propellant.  But the longest leg of the journey is what you need to plan around and that is likely to be the Earth return leg.

Do your remember the discussion we had back on page 39 & 40 when we found that just 100 days Earth return launches from Mars surface would require 8.8 km/s DeltaV and significant aero-braking or propulsive capture at Earth.
That's huge emphasizing the need to make ECLSS closed loop as much as possible.
Quote
Transit times of 120-180 days for Earth return are the range that's actually achievable.
These are the figures I was thinking about.  Do you happen to have the Delta V to give a 100 day to Mars trip?
That also hint SX might like to make it an uncrewed return, but then how do  you get the crew back for the next one?

First Elon has said 25 tonnes cargo on transit back from Mars.  Makes a significant rocket equation difference from the 100 tonnes outbound.  I don't think the MCT will have a crew in the sense we're used to.  No "astronauts".  No "test pilots" especially after the first few flights.  Cargo flights may be unmanned.  Even passenger flights will be automated and each shipment of passengers will have several passenger engineers cross trained to be flight engineers for the trip, skilled enough to implement directions from the ground for ECLS, etc. repairs in flight.  This won't be difficult as especially in the early days the vast majority will be STEM folk & a few construction folk to work with the robots.
« Last Edit: 02/17/2016 01:58 PM by philw1776 »
“When it looks more like an alien dreadnought, that’s when you know you’ve won.”

Offline kaoru

  • Member
  • Posts: 53
  • Ottawa, ON, Canada
    • Sculpt Science
  • Liked: 34
  • Likes Given: 8
Re: MCT Speculation and Discussion Thread 4
« Reply #1699 on: 02/17/2016 11:48 PM »
Here's a model of the passenger module (the nose cone is just for show).  The area per seat/bed is way more than 5m^3 but I still have a lot of things to put in like walls, storage, ducting, electronics, etc..  There is more than enough room for those items, the nose cone area will contain the hygiene/food prep./common stations (I haven't modelled it yet).  Total passenger stations is 96.  Of course, this is just a module with is part of a larger architecture.

Kaoru
« Last Edit: 02/17/2016 11:52 PM by kaoru »

Tags: