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#101 2019-10-28 16:36:16

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,311
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Re: Colonizing / terraforming small asteroids

On the other hand, it has to be warm enough for the plants, since that would be the purpose of the sphere. Though they may not be throughout it.

A large, clear ice sphere could potentially focus sunlight inwards towards its centre. One can imagine a 1km diameter sphere 5AU out that achieves Terran insolation for a 200m diameter sphere in the middle, allowing Trojan colonisation without fusion power. Such worlds would be mini planets surrounded by crystal firmaments. They wouldn't be super isolated, either. 2km/s delta-V (so a chemfuel rocket that can do a total of 4km/s) lets you travel 1.2 million km every week, so your neighbours would be weeks, not months, away. Throw in tethers, and you can go even faster, and I haven't even mentioned beam propulsion yet...


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#102 2019-10-28 17:22:22

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Terraformer re earlier post ....

In an earlier post in this topic (quite recent) I believe you expressed doubt or perhaps skepticism that water could be deposited onto a building structure from the nozzle of a robot device.

Do you have any reference for that belief?

Has an experiment been performed to test your hypothesis?  A LOT of work has been done INSIDE space habitats on orbit, but (so far) I have not heard of a single experiment to see what happens when water is extruded from a nozzle in space/vacuum.

My expectation is that the extruded material will behave almost ** exactly ** the way hot plastic behaves when it is extruded from a 3D printer.

As you must know from observing the operation of 3D Printers, the extruded plastic solidifies almost instantly when it is driven onto a previously laid (and cool) surface.

***
I asked Mr. Google and found this (to me remarkable) site:

http://www.marsicehouse.com/3d-printing-with-ice

Ice habitats on Earth and 3D Printing with ice are not without precedent. In consultation with our Team’s expert scientific advisors, astrophysicists, geologists, structural engineers and renowned 3D printing experts, we have achieved positive experimentation with one to one ice printing and successfully analyzed structural models.

Through an understanding of the physics of phase change and the temperature and pressure conditions of the Martian environment, as well as an understanding of the physical deposition techniques required we've designed a process to turn subsurface ice into water vapor, vapor used to deposit liquid water, in an environment cold enough to print a form in solid ice.

The image that appears with this text appears to show a sizable structure 3D printed as water freezing to ice.

(th)

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#103 2019-10-28 19:02:38

SpaceNut
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Re: Colonizing / terraforming small asteroids

Ice under low gravity will sublime away as it does on mars..

rare earth metals are if found a definate opportunity for export to earth from where ever its found.

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#104 2019-10-28 21:33:38

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut re #103

Can you provide a reference for your statement?

Comets are balls of ice mixed with loose rocks.  It is my understanding comets remain intact in the vacuum of space until they approach a sun.

So I asked Mr. Google and found a wealth of results that discuss sublimation of ice.

One interesting statement I ran across was that ice will sublimate, but so will a rock.  The issue at hand (apparently) is the rate of sublimation.

Here is a reference that suggests comets may NOT sublimate while they are further that 5 AU from the Sun:
http://lasp.colorado.edu/outerplanets/kbos_comets.php

As a comet accelerates towards the Sun, its surface temperature increases, and ices begin to sublimate into gaseous form. By the time the comet comes within about 5 AU of the Sun, sublimation has formed a noticeable atmosphere that easily escapes the comet's weak gravity. The coma forms as the escaping atmosphere drags away dust particles that have been mixed with the sublimating ice. More ice turns into gas as the comet approaches the Sun.

Until we find more definitive research, carried out in space with ice in shadow, we are left with uncertainty about how stable ice would be in space.

My hypothesis would be that ice will NOT sublimate if kept in shadow, because whatever heat energy it contains will gradually radiate into space as black body radiation, leaving the mass of the ice intact.

(th)

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#105 2019-10-28 21:37:36

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re topic in general, and ice in particular ...

Terraformer introduced the idea of using ice in this topic.   The initial idea (as I understood it) was to make a sphere out of ice to enclose a volume, such as a greenhouse for plants.

However, since your topic here is about asteroids, I'd like to invite your evaluation of the idea of spraying the surface of an asteroid with ice, to make a cocoon to hold it together.  The water used to create the enclosure would be totally recoverable after the asteroid has been worked.

(th)

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#106 2019-10-29 03:55:28

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,311
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Re: Colonizing / terraforming small asteroids

TH,

If the water is warm enough to be liquid, then it will evaporate as soon as it reaches vacuum, before freezing into a mist of ice. It won't stay liquid and freeze on contact with ice. You would be essentially blowing fine snow, and doing so with quite a lot of loss. Even doing it from inside a pressurised tent, you need something for the ice to stick to in the first place.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#107 2019-10-29 09:19:17

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 550

Re: Colonizing / terraforming small asteroids

Vapour pressure of ice at different temperatures.  At 0C, vapour pressure is 600Pa.  Even at -80C, the vapour pressure is 0.05Pa.  The ice would need to be contained within an envelope or lightly pressurised cover to prevent it from subliming.

http://www.vaxasoftware.com/doc_eduen/qui/pvh2o.pdf

https://www.lyotechnology.com/vapor-pressure-of-ice.cfm

If the plan is to cover the ice in some way, another option might be to allow an icy body to melt forming a ball of water in space.  Even in the meagre gravity of an iceteroid, hydrostatic pressure would reach atmospheric at a depth of several km.  A submarine city could be built within an envelope of air, provided that the whole structure was suitably ballasted.


Interested in space science, engineering and technology.

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#108 2019-10-29 09:21:14

tahanson43206
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Re: Colonizing / terraforming small asteroids

Terraformer,

You have made a testable prediction.

Please design an experiment that can be performed in space to either confirm or falsify your prediction.

I am pretty sure that the experiment can be designed to fit inside one of the smaller standard packages for space flight experiments.

Please include a video device to record the exact behavior of the water as it leaves the heated nozzle and arrives at the target surface.

(th)

Terraformer wrote:

TH,

If the water is warm enough to be liquid, then it will evaporate as soon as it reaches vacuum, before freezing into a mist of ice. It won't stay liquid and freeze on contact with ice. You would be essentially blowing fine snow, and doing so with quite a lot of loss. Even doing it from inside a pressurised tent, you need something for the ice to stick to in the first place.

Edit: Here is a YouTube video showing a student experiment printing ice cream. An experiment for testing in space would look similar, but the sound would be absent.  What the results would be, for an experiment run in space (or vacuum on Earth) is the question to be answered.

https://youtu.be/iOzHoHttWAI

Last edited by tahanson43206 (2019-10-29 10:45:19)

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#109 2019-10-29 19:46:01

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,870

Re: Colonizing / terraforming small asteroids

The polar crater on the south pole holds ice in the shadow as caused by its depths for the moon. The rim how ever is bathed in solar nearly 24/7 to make that location promissing.

Cere's is one of the promising locations that is an ice world and might serve as a proof of concept.

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#110 2019-10-29 20:36:07

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut ....

Your idea of making an artificial Van Allen belt in another topic is surprising (to me at least) and quite creative.

For your idea below, I immediately thought of Alaskan igloos and 3D Printing of ice structures as already demonstrated on Earth.

Ice structures could (presumably) be 3D Printed on the Moon in permanent shadow, where available on the surface, or in volcanic vent tubes if they exist.

What I'm not clear on (at this point) is whether the tensile strength of ice is sufficient to permit air pressurization for human habitation.  Ice is known of have substantial compression strength.

SpaceNut wrote:

The polar crater on the south pole holds ice in the shadow as caused by its depths for the moon. The rim how ever is bathed in solar nearly 24/7 to make that location promissing.

Cere's is one of the promising locations that is an ice world and might serve as a proof of concept.

***
Following up on the question of tensile strength of ice:
Google came up with a long list of citations about the subject.

The tensile strength of ice varies from 0.7–3.1 MPa and the compressive strength varies from 5–25 MPa over the temperature range −10°C to −20°C. The ice compressive strength increases with decreasing temperature and increasing strain rate, but ice tensile strength is relatively insensitive to these variables.
Review Mechanical properties of ice and snow | SpringerLink
https://link.springer.com › article

https://www.tms.org/pubs/journals/jom/9 … -9902.html

The Structure and Mechanical Behavior of Ice

Erland M. Schulson

ABOUT THE AUTHOR

E.M. Schulson is currently a professor of engineering at Thayer School of Engineering at Dartmouth College.

For more information, contact E.M. Schulson, Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755; (603) 646-2888; fax (603) 646-3856; e-mail erland.schulson@dartmouth.edu.

The article is copyrighted 1999

The article has a list of 80 references.

In the connection of this subject to the overall topic of Mars, I am interested in the potential of building domes on Mars using ice as a component of the structural material.  The article by Dr. Schulson above reminds us of the idea of making an aircraft carrier out of ice in World War II, and how the deficiencies of ice as a structural material were corrected by adding a small amount of wood fiber to the mixture. The resulting material was found to be as strong as concrete, and resistant to artillery blasts.

(th)

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#111 2019-10-30 16:52:32

SpaceNut
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From: New Hampshire
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Posts: 19,870

Re: Colonizing / terraforming small asteroids

As you noted with wood pulp in the water I think fresh versus salt water has some other properties as well.
Will need to covert PSI and Mpa units to see how the levels would play out. The outward pressure for the igloo can be conteracted by pressure forces pushing back on the ice structure.

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#112 2019-10-30 17:20:19

tahanson43206
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Re: Colonizing / terraforming small asteroids

For SpaceNut re #111

Thanks for your follow up regarding the possibility of building ice domes on Mars (or anywhere away from Earth).

Regarding salt ... My understanding is that salt freezes out when ice forms over ocean water.  That is why (I'm pretty sure) icebergs are often thought of as potential sources of fresh water for human consumption.  Various schemes have been proposed to move icebergs South to consumers, but (as far as i know) none of these schemes have materialized. 

The article referenced above includes this line:

Arctic sea ice5 forms directly upon the unidirectional solidification of salt water.

That quote doesn't address the exclusion of salt as I read it, so I recognize the need to go back and look further.

(th)

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#113 2019-10-30 18:23:12

SpaceNut
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From: New Hampshire
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Posts: 19,870

Re: Colonizing / terraforming small asteroids

Ya you are right about the salt...
So we would need to reinforce the ice in layers with something that is a thermal reflector and would give strength to the ice so as to widthstand the pressure of added internal air to the living areas. Something like the thermal blankets come to mind for weaving a shell around and in between the ice layers. Add to the layers aerogel insulation or even glass made from basalt and we have a means to construct with insitu materials.

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#114 2019-10-31 08:09:59

tahanson43206
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Re: Colonizing / terraforming small asteroids

This is primarily for Calliban, and the topic in general ...

Do you buy into the concept that you could become a trillionaire asteroid miner?

If you do, it would make a potentially significant difference in how this topic develops.

Going only from the posts you have provided the global forum audience, I think there is a better than even chance you are worth at least a $2 bet.

That's all I am willing to risk right now, but that could change as this topic advances.

Related to the above is the question of whether you have had a chance to look at the NASA mission planning site that SpaceNut found?

My understanding (or at least first impression) is that the site is designed for serious mission planners, including those who are intending to make proposals to NASA.

You may well have chosen an asteroid to focus upon to the exclusion of all other distractions, but if you have, I missed it.

I was interested in Apophis, but my impression is you have not yet found it compelling.  I understand that size of the asteroid you want to select is an important consideration, along with orbit and spectral characteristics.

(th)

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#115 2019-10-31 11:21:56

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 550

Re: Colonizing / terraforming small asteroids

tahanson43206 wrote:

This is primarily for Calliban, and the topic in general ...

Do you buy into the concept that you could become a trillionaire asteroid miner?

If you do, it would make a potentially significant difference in how this topic develops.

Going only from the posts you have provided the global forum audience, I think there is a better than even chance you are worth at least a $2 bet.

That's all I am willing to risk right now, but that could change as this topic advances.

Related to the above is the question of whether you have had a chance to look at the NASA mission planning site that SpaceNut found?

My understanding (or at least first impression) is that the site is designed for serious mission planners, including those who are intending to make proposals to NASA.

You may well have chosen an asteroid to focus upon to the exclusion of all other distractions, but if you have, I missed it.

I was interested in Apophis, but my impression is you have not yet found it compelling.  I understand that size of the asteroid you want to select is an important consideration, along with orbit and spectral characteristics.

(th)

Tahanson, I am a middle management engineer who earns before tax, about $100,000 in US money; about £80,000 in UK money.  A good wage that allows me to support my family comfortably, but I am not rich by any definition.  I am limited on what holidays I can afford on the surface of the Earth.  I will not be financing any trips to near-earth asteroids unless there are some much unexpected developments in propulsion technology over the next 20 years; nor would I be a good bet for the asteroid equivalent of Robert Zubrin.  I have limited mechanical and nuclear engineering expertise and am respected in the limited circles of my profession, but I am not on the same level as a man like Zubrin.

That said; feel free to share whatever we have discussed here with whoever you like.  If it is useful to any real world space agency, then it was time well spent.  We have only discussed here some interesting concepts; we have not developed practical mission architecture yet.  And I doubt that I have the expertise to take things very much further.  Maybe you and some of the others do.

Regarding Apophis, the size of the body would require that we modify the initial concept that I raised.  A bag big enough to allow a 300m asteroid to be rotated to provide lunar levels of gravity and 0.5bar internal pressure in any tunnels that we dig; would blow the lift capacity of any heavy-lift vehicle on the drawing board.  To make that affordable would require ISRU which SpaceNut has done a good job of expanding upon.  I think it would be difficult to mine enough material from Apophis in zero-g and construct a fibreglass bag from the mined material.  This is why I suggested that we first focus on a smaller target that can be enclosed with a bag launched from Earth.  We could spin up the body to provide gravity and dig tunnels that could be pressurised.  We would build our 'bag factory' inside the tunnels, using waste silicates from mining as feedstock.  Precious metals would go back to Earth; the bag that we make using waste materials would then be used to repeat the process on a larger asteroid.  A staged approach.

The other problem with Apophis is that it appears to be a resource poor LL Condrite that contains little free metal.  We cannot be very sure based on spectroscopic data.  When it comes to earning money from asteroid mining, the best targets contain an abundance of free iron that contains dissolved platinum group metals and cobalt.  These are the things that we have a chance of returning to Earth and selling for profit with the correct mission architecture.  So choosing a target that is rich in these things really is important.  Other useful materials are volatiles like carbon and water, which are useful for all sorts of things, including life support.  Other bonuses include a low delta-v orbit w.r.t Earth.  We have also discussed asteroids with orbits that lie between Earth and Mars, which could be used as cyclers.

The thing that leads me to believe that near-Earth asteroids are the best near-term targets for manned space flight is that they appear to be the only destinations that allow space flight to be profitable in a business sense, with realistic investments.  There are clearly identified minerals that can be mined and sold with profit with limited outlay.  That isn't true for Mars or the Moon.

Last edited by Calliban (2019-10-31 11:24:10)


Interested in space science, engineering and technology.

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#116 2019-10-31 11:54:53

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re #115

Thank you for your thoughtful reply!

SearchTerm:AsteroidSelection
SearchTerm:CV
Author:Calliban

(th)

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#117 2019-10-31 17:58:30

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re topic ...

If you are willing to pick an asteroid from all you have considered to date, or perhaps a new one, I'll see if I can make head or tails of the NASA mission planning site.  My understanding is the site is pre-loaded with a number of Solar System objects, so the asteroid you pick may already be in the list.  That would help if the listing includes orbital elements, which seems likely, if the object is listed at all.

(th)

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#118 2019-11-01 11:11:06

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 550

Re: Colonizing / terraforming small asteroids

tahanson43206 wrote:

For Calliban re topic ...

If you are willing to pick an asteroid from all you have considered to date, or perhaps a new one, I'll see if I can make head or tails of the NASA mission planning site.  My understanding is the site is pre-loaded with a number of Solar System objects, so the asteroid you pick may already be in the list.  That would help if the listing includes orbital elements, which seems likely, if the object is listed at all.

(th)

I think it needs to work the other way round.  We decide what we are looking for and search the minor planet database for a match.


Interested in space science, engineering and technology.

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#119 2019-11-01 13:07:58

tahanson43206
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Re: Colonizing / terraforming small asteroids

For Calliban re #118

Thank you for continuing the flow here.

I'm looking for an excuse to try to deal with the NASA mission planning site SpaceNut found, and it's a LOT more fun if the mission I'm going to try to plan is of interest to someone else.  If I can figure out how to use the site, i'll report what I learn here, and others can have a go themselves.

In other words, it doesn't matter to me what object you decide to investigate, as long as you pick one << grin >>

It is entirely possible I will find myself way over my head within 30 minutes, but I'm not out to impress anyone, at this point in my life.

Edit: You (on the other hand) have an entirely different goal set (as nearly as I can tell).  If I understand correctly, your interest is in finding an attractive object, based upon known data, and of the two, I would imagine your goal will be more difficult to achieve, but you ** may ** be able to enlist one or two more members of the active forum to help. 

(th)

Last edited by tahanson43206 (2019-11-01 13:11:33)

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#120 2019-11-01 20:13:09

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,870

Re: Colonizing / terraforming small asteroids

I am getting a certificate error so be careful of the site maybe research it a bit more as the link from a page ago post #80 may not be what we would want.

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#121 2019-11-01 20:55:16

SpaceNut
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Posts: 19,870

Re: Colonizing / terraforming small asteroids

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#122 2019-11-02 06:45:39

tahanson43206
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Registered: 2018-04-27
Posts: 3,736

Re: Colonizing / terraforming small asteroids

For SpaceNut re NASA mission planning site ...

Thanks for the alert regarding a certificate error ...

The site seems ok on my system.  I'll try it on others here to be sure it is alright.

I'm running Ubuntu 64 and Chromium at current patch levels.

SearchTerm:NASAMissionPlanning

https://www.nasa.gov/centers/ames/engin … ature.html

(th)

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#123 2019-11-02 22:33:43

tahanson43206
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Registered: 2018-04-27
Posts: 3,736

Re: Colonizing / terraforming small asteroids

For Calliban ...

In reading kbd512's new topic about extracting water on Mars, I was inspired to wonder if a water rich asteroid could be dropped onto Mars to accelerate the process of water collection for support of human missions.

I asked Mr. Google "water rich asteroids" and received back a sizable result list.

Among the first entries are ones suggesting that a water rich asteroid might be a more attractive target for an asteroid mining expedition that would be an asteroid with metal content, simply because of the immediate market opportunity such an asteroid would provide.

https://www.space.com/water-rich-astero … -fuel.html

This article was published relatively recently.

A recent study suggested that roughly 1,000 water-rich, or hydrated, asteroids near our planet are easier to reach than the lunar surface is. While most of these space rocks are only a few feet in size, more than 25 of them should be large enough to each provide significant water. Altogether, the water locked in these asteroids should be enough to fill somewhere around 320,000 Olympics-size swimming pools — significantly more than the amount of water locked up at the lunar poles, the new research suggested.

(th)

Last edited by tahanson43206 (2019-11-02 22:42:27)

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#124 2019-11-03 14:34:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,870

Re: Colonizing / terraforming small asteroids

Water delivery from mined source would benefit all of the expiditions for moon or mars as the water creates the means for less energy for the surface operations all the way around to be able to stay alive from making fuel to having oxygen from a simple process.

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#125 2019-11-04 16:06:06

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 550

Re: Colonizing / terraforming small asteroids

If stainless steel production peaks, then humanity would be in serious trouble.

http://newmars.com/forums/viewtopic.php … 63#p161863

You can't make food without fertiliser.  You can't make fertiliser without nitric acid.  And you can't make nitric acid without stainless steel.  Less stainless steel means less food.  The day may not be long off, where asteroid nickel mining is the difference between life and death for a lot of people.


Interested in space science, engineering and technology.

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