Author Topic: MCT Speculation and Discussion Thread 4  (Read 604168 times)

Online Robotbeat

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Re: MCT Speculation and Discussion Thread 4
« Reply #1800 on: 02/27/2016 05:18 PM »
According to Musk, Falcon 9 1st stage separation velicity drops from 9 km/s with drone landing to 6km/s with dry landing.

Source? That seems incredibly unlikely. 9km/s at staging is enough to carry the fully fuelled ~100 tonne second stage into LEO without firing its engines. That would make the F9 first stage a 110 tonne to LEO SSTO!

(Sorry, a 110 tonne to LEO reusable SSTO.)
Indeed.

I'd settle for a reusable TSTO.

BTW has anyone mentioned the mass fraction this thing needs?

AIUI people have said a 100 day trip needs 8.8Km/s from LEO. ...
Not right. More like 5-7km/s from LEO if you aerocapture at the other end. 8.8km/s would be doing a propulsive capture, which simply isn't going to happen. SpaceX will be doing aerocapture for the majority of the capture delta-v.

This is what happens when people (not saying this is you, john smith) use an online tool or online numbers without reading the fine print or understanding where the numbers come from.

http://trajbrowser.arc.nasa.gov/
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 jsgirald

Re: MCT Speculation and Discussion Thread 4
« Reply #1801 on: 02/27/2016 05:21 PM »
Even if the BFR is relatively a smaller proportion of the stack, it is hard to see cutoff not being at least a little bit down range.  So, I would claim you can push the design for a somewhat smaller penalty for dry landing - but not penalty free.

I've been wondering myself what might be the ideal proportion. Playing around with the equations I got stage 1 to something below 60% of the total mass (the whole stack would have a mass similar to a Saturn V for ~200 mt to LEO), and a staging altitude similar to Falcon 9, which I admit looks wrong. This would need about 5 tanker missions to refuel before TMI.

Perhaps a more knowlegeable member could provide a better solution??
"For every expert, there is an equal and opposite expert".

Offline Burninate

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Re: MCT Speculation and Discussion Thread 4
« Reply #1802 on: 02/27/2016 05:35 PM »
According to Musk, Falcon 9 1st stage separation velicity drops from 9 km/s with drone landing to 6km/s with dry landing.

Source? That seems incredibly unlikely. 9km/s at staging is enough to carry the fully fuelled ~100 tonne second stage into LEO without firing its engines. That would make the F9 first stage a 110 tonne to LEO SSTO!

(Sorry, a 110 tonne to LEO reusable SSTO.)
Indeed.

I'd settle for a reusable TSTO.

BTW has anyone mentioned the mass fraction this thing needs?

AIUI people have said a 100 day trip needs 8.8Km/s from LEO. ...
Not right. More like 5-7km/s from LEO if you aerocapture at the other end. 8.8km/s would be doing a propulsive capture, which simply isn't going to happen. SpaceX will be doing aerocapture for the majority of the capture delta-v.

This is what happens when people (not saying this is you, john smith) use an online tool or online numbers without reading the fine print or understanding where the numbers come from.

http://trajbrowser.arc.nasa.gov/

In a 2-dimensional simplification, we go over the dV's required here:

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436054#msg1436054

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436460#msg1436460

0) You are correct, we find only about 3.2+2.2=5.4km/s for LEO to Mars 100d-transit escape burn, before accounting for EDL & without accounting for capture.  EDL dV needs seem to be contentious, I add a conservative 2km/s for 7.4km/s total.  Note again this is a circular coplanar simplification with launch direct to ecliptic; Reality is likely to be a little bit worse.

1) We have never aerocaptured at Mars before

2) We expect the Mars aerocapture to be especially difficult because the Martian atmosphere's thickness is apparently somewhat variable.

3) The required aerocaptures on a 100d Earth-Mars trip are rather extreme for aerocaptures, probably requiring MAC or some novel means;  I have read published suggestions that this is unfeasible in a traditional heatshielded lander, though I cannot verify them.  It needs to dissipate 9.3km/s of velocity in one pass to get into a high elliptical, but captured orbit, and more if you're doing a direct entry.  A minimum aerocapture from slow Hohmann transfer is more like 1.0km/s.

4) A 100d direct return trip with 'free' aerocapture at Earth is likely to require extreme amounts of dV for the Mars launch + escape burn, the link mentioned 8.8km/s.

Therefore:

I consider 100d transfers a bit of a silly overreach, at least at the beginning;  We know that the extra 80 days of microgravity and radiation isn't statistically prohibitive, and I fear that the changes required for fast transfers, at least ones in the mission architecture that has been described (LEO & MS refueling only) would be economically and physically prohibitive.  The goal being asserted on the business end, single-synod reuse, is probably unfeasible without a large propellant production facility already emplaced on the Mars surface with a hard pad - ISRU cannot be reasonably accomplished in a short-stay.  And something's going to need to build that facility;  If that something never gets off the ground because the design is unworkable at 100d transits, then this all fails to happen.

SEP methane propellant depots to LMO, then HEO, then HMO, let you cut the dV needs substantially if you're willing to set up a Conga line of them and give each one 2-5 years to get in place.
« Last Edit: 02/27/2016 05:50 PM by Burninate »

Online Robotbeat

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Re: MCT Speculation and Discussion Thread 4
« Reply #1803 on: 02/27/2016 07:45 PM »
I've simulated Mars aerocapture coming in from many different hyperbolic velocities. 100 day transfers DO NOT need MAC. PICA-X is what will be used.

2km/s is ridiculously conservative. More like 0.5-1.5km/s.

Who cares if we've never aerocaptured at Mars before? It's certainly possible. Why must our decisions be constrained by the same kind of compound conservatism that continuously makes NASA choose battlestar galactica expendable architectures with a billion different components and vehicle configuration changes (thus defeating any supposed safety advantage)?

100 day is to Mars, as Musk has REPEATEDLY said. NEVER has Musk said 100 days /back/. That means it'd be longer back.

Mars' atmosphere is plenty thick enough for aerocapturing.

100 day transfers is not silly anything and would not be even close to the most difficult entry/reentry ever attempted, though I would expect early missions would use lower energy transfers.

And yes, MCT will need ISRU infrastructure in place. That has been clear since forever, so why would you question that?
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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 Robotbeat

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Re: MCT Speculation and Discussion Thread 4
« Reply #1804 on: 02/27/2016 07:47 PM »
Using several conservative assumptions is a good way to guarantee you'll develop an architecture which has no bearing on SpaceX's actual plans.
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

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Re: MCT Speculation and Discussion Thread 4
« Reply #1805 on: 02/27/2016 08:54 PM »
With all the concerns (valid) about closed systems, why not consider CO2 washing machines for MCT or BFS whatever-it's-called passengers?

http://e3tnw.org/ItemDetail.aspx?id=512

"About 32 dry cleaning companies in the country are currently cleaning with the Glacier liquid CO2 system supplied by Solvair of Naperville, Illinois. The load capacity of their machine is about 25 kg or 55 pounds.  CO2Nexus of Littleton, Colorado has developed three models of their TERSUS® system. These supercritical carbon-dioxide based laundry systems are suitable for commercial and industrial uses and can accommodate loads of 100 and 200 pounds per cleaning cycle.  At high pressures, CO2 enters a liquid supercritical state and can serve as a washing fluid. The liquid CO2 has low viscosity and surface tension allowing for superior pore penetration and better cleaning action. After cleaning is completed, the pressure is reduced and the CO2 flashes to a gaseous state, eliminating the need for a drying cycle. The gaseous CO2 is captured, filtered and distilled, and then reused. The units are compact, save both energy and water, and extend garment life due to the lack of need for high temperatures and agitation."

Another article...

http://www.trendhunter.com/trends/supercritical-washing-machine



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Offline kaoru

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Re: MCT Speculation and Discussion Thread 4
« Reply #1806 on: 02/28/2016 07:19 PM »
Here's a pic of my upper stage/BFS engine module so far.  The volume of the LOX tank is ~581 m3 and for the CH4 tank it's ~360 m3.  This is to contain densified LOX at -205C (1248.9 kg/m3) or 725,773 kg of LOX.  For CH4 tank, it's densified at -180C (448.31 kg/m3) or 161,503 kg of liquid CH4.  Of course, this assumes the following values: a LOX to CH4 ratio of 3.5:1 where the vacuum Raptors are 2300 kN (x4) at ISP of 380 s (vac) for 397 seconds burn time.

I've loaded an extension to SketchUp that computes the dry weight of the model.  Unfortunately, having complex models really takes a long time to compute weight so I don't have the weights yet; it's still running.

Everything in the model is a component and have an assigned material density.  For the most part, I using an aluminium alloy 7075-T6 which has a density of 2810 kg/m3; tracking down densities of aluminium lithium alloys is little harder so I assume that the structure could be made lighter (T6 is at the higher end weight wise).

My goal is to model all the major components for the engine module that has weight:
* 4 X Vacuum Raptors (with cantilever mounts for Supersonic Retro-Propulsion SRP)
* 4 X Retractable landing legs (leveling & shock absorbing)
* Integrated Vehicle Fluids (CH4 ICE for compressors and electricity generator)
* Cargo-level ECLSS
* CBM/Airlock & PICAX heat shield hatch, pressurized tunnel.
* Service deck with aux. control.
* Batteries, Control Moment Gyroscopes (4 x CMG).
* Solar panels and heat radiators.

Of course, modelling all of that takes a bit of creative license and time.

Diameter: 10.1 meters
Height:  My system is busy calculating weight; but I believe it's 22 meters give or take.

Offline Long EZ

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Re: MCT Speculation and Discussion Thread 4
« Reply #1807 on: 02/28/2016 08:31 PM »
When MCT departs for Mars the propellant tanks will be mostly empty, having only enough for Mars EDL + reserve. To keep these from boiling off during Mars transit it will require active cooling. My thought is that perhaps it would be better to store these is separate tanks. A tank in a tank? The point being that the inner tank would have additional insulation to reduce the active cooling energy required. My first thought was that the tank in a tank could be a central column inside methane and LOX tanks. Another thought was that these could be large insulated pressure vessels in a lower equipment bay. After landing these tanks could be removed and used as habitation module: large insulated pressure vessels.

Has this been suggested already? Is it a reasonable idea?
Thanks
Long EZ builder / pilot
« Last Edit: 02/28/2016 08:35 PM by Long EZ »

Offline hkultala

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Re: MCT Speculation and Discussion Thread 4
« Reply #1808 on: 02/28/2016 08:48 PM »
According to Musk, Falcon 9 1st stage separation velicity drops from 9 km/s with drone landing to 6km/s with dry landing.

Source? That seems incredibly unlikely. 9km/s at staging is enough to carry the fully fuelled ~100 tonne second stage into LEO without firing its engines. That would make the F9 first stage a 110 tonne to LEO SSTO!

(Sorry, a 110 tonne to LEO reusable SSTO.)
Indeed.

I'd settle for a reusable TSTO.

BTW has anyone mentioned the mass fraction this thing needs?

AIUI people have said a 100 day trip needs 8.8Km/s from LEO. ...
Not right. More like 5-7km/s from LEO if you aerocapture at the other end. 8.8km/s would be doing a propulsive capture, which simply isn't going to happen. SpaceX will be doing aerocapture for the majority of the capture delta-v.

This is what happens when people (not saying this is you, john smith) use an online tool or online numbers without reading the fine print or understanding where the numbers come from.

http://trajbrowser.arc.nasa.gov/

In a 2-dimensional simplification, we go over the dV's required here:

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436054#msg1436054

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436460#msg1436460

0) You are correct, we find only about 3.2+2.2=5.4km/s for LEO to Mars 100d-transit escape burn, before accounting for EDL & without accounting for capture.  EDL dV needs seem to be contentious, I add a conservative 2km/s for 7.4km/s total.  Note again this is a circular coplanar simplification with launch direct to ecliptic; Reality is likely to be a little bit worse.

1) We have never aerocaptured at Mars before

2) We expect the Mars aerocapture to be especially difficult because the Martian atmosphere's thickness is apparently somewhat variable.

3) The required aerocaptures on a 100d Earth-Mars trip are rather extreme for aerocaptures, probably requiring MAC or some novel means;  I have read published suggestions that this is unfeasible in a traditional heatshielded lander, though I cannot verify them.  It needs to dissipate 9.3km/s of velocity in one pass to get into a high elliptical, but captured orbit, and more if you're doing a direct entry.  A minimum aerocapture from slow Hohmann transfer is more like 1.0km/s.

4) A 100d direct return trip with 'free' aerocapture at Earth is likely to require extreme amounts of dV for the Mars launch + escape burn, the link mentioned 8.8km/s.


umm. Are you calculating delta-v by calculationg sums of partial delta-v:s from a delta-v map even when you can do the whole thing in one burn?

In those cases Oeberth effect gives huge benefit and the required delta-v is only the Pythagoran sum of partial delta-v's that are done together, not direct sum of those.

3.2km/s + 2.2 km/s done together at pegiree, high speed velocity, costs only sqrt(3.2^2 + 2.2^2) = 3.88 km/s.

Offline MikeAtkinson

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Re: MCT Speculation and Discussion Thread 4
« Reply #1809 on: 02/28/2016 08:59 PM »
When MCT departs for Mars the propellant tanks will be mostly empty, having only enough for Mars EDL + reserve. To keep these from boiling off during Mars transit it will require active cooling. My thought is that perhaps it would be better to store these is separate tanks. A tank in a tank? The point being that the inner tank would have additional insulation to reduce the active cooling energy required. My first thought was that the tank in a tank could be a central column inside methane and LOX tanks. Another thought was that these could be large insulated pressure vessels in a lower equipment bay. After landing these tanks could be removed and used as habitation module: large insulated pressure vessels.

Has this been suggested already? Is it a reasonable idea?
Thanks
Long EZ builder / pilot

I have thought ever since we heard of MCT that secondary tanks may be used. As well as the advantages for cooling I can think of three other reasons, which I'll leave as an exercise for the reader.

The big question is whether the added mass and complexity of the extra tanks is worth it.

Offline Burninate

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Re: MCT Speculation and Discussion Thread 4
« Reply #1810 on: 02/28/2016 10:09 PM »
According to Musk, Falcon 9 1st stage separation velicity drops from 9 km/s with drone landing to 6km/s with dry landing.

Source? That seems incredibly unlikely. 9km/s at staging is enough to carry the fully fuelled ~100 tonne second stage into LEO without firing its engines. That would make the F9 first stage a 110 tonne to LEO SSTO!

(Sorry, a 110 tonne to LEO reusable SSTO.)
Indeed.

I'd settle for a reusable TSTO.

BTW has anyone mentioned the mass fraction this thing needs?

AIUI people have said a 100 day trip needs 8.8Km/s from LEO. ...
Not right. More like 5-7km/s from LEO if you aerocapture at the other end. 8.8km/s would be doing a propulsive capture, which simply isn't going to happen. SpaceX will be doing aerocapture for the majority of the capture delta-v.

This is what happens when people (not saying this is you, john smith) use an online tool or online numbers without reading the fine print or understanding where the numbers come from.

http://trajbrowser.arc.nasa.gov/

In a 2-dimensional simplification, we go over the dV's required here:

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436054#msg1436054

http://forum.nasaspaceflight.com/index.php?topic=37808.msg1436460#msg1436460

0) You are correct, we find only about 3.2+2.2=5.4km/s for LEO to Mars 100d-transit escape burn, before accounting for EDL & without accounting for capture.  EDL dV needs seem to be contentious, I add a conservative 2km/s for 7.4km/s total.  Note again this is a circular coplanar simplification with launch direct to ecliptic; Reality is likely to be a little bit worse.

1) We have never aerocaptured at Mars before

2) We expect the Mars aerocapture to be especially difficult because the Martian atmosphere's thickness is apparently somewhat variable.

3) The required aerocaptures on a 100d Earth-Mars trip are rather extreme for aerocaptures, probably requiring MAC or some novel means;  I have read published suggestions that this is unfeasible in a traditional heatshielded lander, though I cannot verify them.  It needs to dissipate 9.3km/s of velocity in one pass to get into a high elliptical, but captured orbit, and more if you're doing a direct entry.  A minimum aerocapture from slow Hohmann transfer is more like 1.0km/s.

4) A 100d direct return trip with 'free' aerocapture at Earth is likely to require extreme amounts of dV for the Mars launch + escape burn, the link mentioned 8.8km/s.


umm. Are you calculating delta-v by calculationg sums of partial delta-v:s from a delta-v map even when you can do the whole thing in one burn?

In those cases Oeberth effect gives huge benefit and the required delta-v is only the Pythagoran sum of partial delta-v's that are done together, not direct sum of those.

3.2km/s + 2.2 km/s done together at pegiree, high speed velocity, costs only sqrt(3.2^2 + 2.2^2) = 3.88 km/s.

That is already factored in to the spreadsheet tool I used.  Not using Oberth, the figures would be much, much higher.

Offline kaoru

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Re: MCT Speculation and Discussion Thread 4
« Reply #1811 on: 02/29/2016 02:35 AM »
When MCT departs for Mars the propellant tanks will be mostly empty, having only enough for Mars EDL + reserve. To keep these from boiling off during Mars transit it will require active cooling. My thought is that perhaps it would be better to store these is separate tanks. A tank in a tank? The point being that the inner tank would have additional insulation to reduce the active cooling energy required. My first thought was that the tank in a tank could be a central column inside methane and LOX tanks. Another thought was that these could be large insulated pressure vessels in a lower equipment bay. After landing these tanks could be removed and used as habitation module: large insulated pressure vessels.

Has this been suggested already? Is it a reasonable idea?
Thanks
Long EZ builder / pilot
My model shown in my previous post addresses this by an Integrated Vehicle Fluids (IVF) system.  Though speculation on my part, something like this would have to be implemented.  First, the Dracos (RCS) would be converted to CH4/LOX with electric ignition since hydrazine is hard to come by on Mars.  This means that pressurized CH4/LOX is required (doing away with helium).  The IVF is what would maintain these tanks using the boil off of the main tanks.  The IVF would use some of the CH4/LOX boil off to run the Internal Combustion Engine (ICE) that generates electricity and runs compressors to pressurize those tanks and chillers to cool/maintain the fuels in the main tanks.  The trick is to build a system that is light (plumbing/compressors can be heavy) and have really good heat radiators.

In my model, my plan is to have the IVF system in the stern (bottom) in a pressurized section.  The reason is to take advantage of the main tank plumbing (for the Raptors) and there is room for tankage, etc.  Also, since this system would be just as critical as ECLSS, the central tunnel can access the equipment for service if need be.  The central tunnel serves multiple purposes beyond just being a way to get to the surface.  It's also a gangway for plumbing, etc. to the bow.  The idea is that multiple of these modules can link up end on end, like Lego bricks.  Update:  Also, having the IVF and all the plumbing for connections to other modules also means that on the surface of Mars it can connect up to ISRU equipment for refuelling.  Going to need that big time.

Also, it's already a given that it'll take multiple LEO launches to get fuel, cargo, and passengers into orbit.  Having one upper stage (like my model) reusable for multiple purposes (that have some commonality) is the most efficient means (in both cost and weight).

BTW, I was calculating the weight of my model but the numbers were wildly off.  Turns out the plugin I was using can only calculate object as if they are solid, aka my tanks were being treated as solid aluminium.  I may have to do this old school... find the surface area of tanks, account for the thickness and compute the volume.

Update: Here's my latest snapshot with a man to show scale.
Kaoru
« Last Edit: 02/29/2016 05:57 AM by kaoru »

Offline john smith 19

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Re: MCT Speculation and Discussion Thread 4
« Reply #1812 on: 03/01/2016 09:09 AM »
Quote from: John Smith 19

Interesting idea. Something that should be testable on the ISS.

The joker in the pack is not the vacuum. It's the temperature in the lock. IIRC in full sunlight you're talking c200c, in full shadow -200c.

I think cold would do less damage but I'd still suspect it would do so much damage they would literally crumble in your hands.

But note it's still basically an open loop system and the goal should always be to close the loops.
200C is actually fine for cotton as long as it's fairly quick. Keep it out there too long and it'd degrade at those temperatures. Anyway, the actual temperature would depend on the color of the cloth and other aspects.
I did not know cotton was good to 200c.  Working out it's actual final temperature inside an airlock would be difficult enough but once you're in direct sunlight then you're into the spectral absorbance and emissivity of the fabrics. Has anyone even measured these factors?
« Last Edit: 03/01/2016 09:14 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.

Offline john smith 19

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Re: MCT Speculation and Discussion Thread 4
« Reply #1813 on: 03/01/2016 09:12 AM »
This is what happens when people (not saying this is you, john smith) use an online tool or online numbers without reading the fine print or understanding where the numbers come from.

http://trajbrowser.arc.nasa.gov/
True.

Different assumptions can have a very large impact on what people think is and is not possible.

I merely took the figures given and ran with them. The MCT tab of the next version of my costing game will let people put their own numbers in and see what comes out in terms of expected size.


As promised here is the new version. As usual date entry is to the Blue bordered cells.

The MCT tab let's you put in choose a delta V and see what that does to your expected gross weight needed in LEO. Note while the figure for resource use per day is the NASA standard (11lb or 5Kg/day) it can be changed, reflecting peoples beliefs in how much (or little) closed loop life support can improve on it. Likewise although it's labelled "Raptor Vac Isp" you can provide any Isp you want. It's pretty astonishing what a 4000sec engine (IE an Ion thruster) can to size to LEO, but this is just the rocket equation, and does not take into account any tricky orbital mechanics, multiple burns, slingshots etc.

I've also finally gotten round to fleshing out the "design your rocket" tab. This uses the ULA chart for the cost and weight of 2 stage LV components as a starting point for seeing how different assumptions affect the final outcome. If you use the UL defaults and start with a gross takeoff weight and cost that's how the different parts will break out in terms of mass and cost.

I encourage anyone who thinks they can do better than ULA to do so and to give me any feedback.
« Last Edit: 03/01/2016 12:45 PM 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 oldAtlas_Eguy

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Re: MCT Speculation and Discussion Thread 4
« Reply #1814 on: 03/02/2016 04:05 PM »
An item is that the colonization policy would be a strict 50/50 male/female ratio. For there and back mission the ratio could be anything but for colonization it would have to be 50/50.

Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1815 on: 03/02/2016 04:31 PM »
An item is that the colonization policy would be a strict 50/50 male/female ratio. For there and back mission the ratio could be anything but for colonization it would have to be 50/50.

Excuse me but that was not the sort of ratio seen in historical colonization efforts and I really doubt that it would pertain today. What justification do you have for imposing such a ratio? Is sexual orientation going to be a selection criteria for colonization? Is intention to have children going to be a selection criteria? Is fertility? Is philosophical commitment to monogamy going to be a selection criteria?
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline The Amazing Catstronaut

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Re: MCT Speculation and Discussion Thread 4
« Reply #1816 on: 03/02/2016 06:27 PM »
An item is that the colonization policy would be a strict 50/50 male/female ratio. For there and back mission the ratio could be anything but for colonization it would have to be 50/50.

Excuse me but that was not the sort of ratio seen in historical colonization efforts and I really doubt that it would pertain today. What justification do you have for imposing such a ratio? Is sexual orientation going to be a selection criteria for colonization? Is intention to have children going to be a selection criteria? Is fertility? Is philosophical commitment to monogamy going to be a selection criteria?

If anything a sexual vetting process would be unethical by the standards of most. You can't turn away people because they might have had partners on Earth who they preserve long distance relationships with, are sterile, are asexual, simply enjoy sex for pleasure rather than reproduction, don't want any more kids, are LGBT+, are polyamorous or simply want to spend their time working rather than spending time intimately with other people whilst their on mars (as many choose to do on Earth).

Certainly, if you end up with 80% male applicants all from the same small town in the same part of the world there will need to be some filtering - but you can't invalidate skilled, intelligent people because of deeply personal elements of their life that they have no control over. If a Mars colony is going to be representative of humanity, you're going to get people from every walk of life (who can afford the trip) applying.
« Last Edit: 03/02/2016 06:30 PM by The Amazing Catstronaut »
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Offline Hauerg

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Re: MCT Speculation and Discussion Thread 4
« Reply #1817 on: 03/02/2016 06:43 PM »
Getting a tiny little bitt off course, aren't we.

Offline spacenut

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Re: MCT Speculation and Discussion Thread 4
« Reply #1818 on: 03/02/2016 06:52 PM »
If left alone, the natural selection process of humans ends up being close to 50-50.  Only in the 20th century have these changes taken place, like birth control, nuclear families, then other choices.  Most all world societies traditionally have had a male-female relationship selection process.  Occationally there were deviations from the norm like Rome with gay Ceasars, and multiple wives like Islamic countries, but almost all of humanity societies have been 50-50 man-woman relationships.  It will probably require this for colonization to take hold.  Otherwise it will be like Europe, Japan, and American whites today with decreasing populations. 

Sure there will be a need for all types of educated people to make it work, but they will have to have families for colonization to take hold.  Something interesting I learned, when America declared it's independence from England, America had the most educated population in the world at the time.  More Americans could read and write than Europeans.  Because of religious freedom coupled with the "age of enlightenment" education was important.  Most of the original universities were started by various churches.  "Sunday School" was started to teach kids how to read.  So it is with Martian colonization, the most educated people, with various skills, will have to be the ones to colonize and grow the colony. 

Offline nadreck

Re: MCT Speculation and Discussion Thread 4
« Reply #1819 on: 03/02/2016 11:37 PM »
Continuing the gender and reproductive discussion here: http://forum.nasaspaceflight.com/index.php?topic=39719.msg1498881#msg1498881
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

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