Mars Colonization Discussion Thread

[PB666]

23 minutes ago, DAL59 said:

Neither exist on a venusian airship.  

Uh, huh as you get closer to the sun the intensity of magnetic storms increases. The affect of no gravity during the flight are comparable. Before Elon Musk can die on Mars he first has to survive the trip to Mars (or Venus).

So a rotating ship as mentioned by kerbiloid with 1 meter thick composite with a density of 2.0 is 2000kg per cubic meter.

For a rotating ship to work the human body would on average need to experience 1 g of force, this means either 2 to 0 g. But the effect of less gravity also includes the eyes. Consequently the head needs at least half of a g-force.

The average human of 6 feet tall would need to be in a cylinder. And the device needs to be balanced, iow it would hold two individuals. Such a device 2/3 of a meter by 1/2 a meter (minimally) or about 7/12 of a meter in inside diameter and an exterior diameter of 19/12ths of a meter would have a crosssectional area of 1.968 square meters at the base (v=1.968 m3) and 1.7002 along the column. In order for the g force to be 4.9a at top of head and average 9.8a over then entire length of the body (4.9 + X)/2 = 9.8  then at the feet G should be 14.7 a. The column should be 2.74 meters in length( v = 4.65 m3) The mass of the body, alone would be 2 x (4.65 + 1.968) = 13.25 m3 x 2000 kg/m3 = 26,504 kgs.

See other thread about the amount of ground rocket to escape velocity. Basically you need An atlas IV rocket to send 3000kg to escape velocity. Double that to reach mars and retro into orbit. So to get 26,504 from a launch pad to Mars you would need the equivilent of 17 atlas 4 rockets. This does not include non-g areas of ship, its food and water supplies or the mars or venutian lander. So lets just say a launch rocket about 5 times the size of a SaturnV rocket.

Yeah, no, thats not a solution.

[Streetwind]

Looks like this might be relevant here.

An interview with John Amabile, who wrote a book detailing how to terraform and colonize Mars and Venus within a human's lifetime. Now, I'm sure everyone has their own opinion on whether or not that's a reasonable estimate (I certainly do have one), but discussing that essentially boils down to crystal ball reading, and so is fairly pointless. Maybe a more interesting topic is the details of how exactly this person thinks it could be achieved.

To start with, he outlines that the following should happen:
- The USA exits the Outer Space Treaty, thereby becoming able to declare themselves owner of property in space
- The USA invites its numerous allies to also exit the OST, and instead join them in their efforts, so that a new power block is formed that can hold its own against the UN and the rest of the world
- In return, each country joining would receive a guarantee along the lines of "own 1% of the solar system" (exact details up for negotiation)
- The various countries would then sell or lease parts of their stakes to private companies for money, or form state owned companies dedicated to resource exploitation
- Space exploration would be driven primarily by market forces - in other words, if there's money to be made, people will be all over it
- The USA uses its vast amounts of existing military technologies to enable rapid resoruce exploitation and planetary colonization by asteroid bombardment
- Asteroid mining, orbital fuel depots and space tugs feature heavily in this vision, as does nuclear thermal propulsion

The author posits that all of this is possible now, using existing technologies. The main thing holding it back is that "nobody cares". As in, the general public neither knows nor cares that this might be possible. He gives the comparison that if the government decided to declare airplanes illegal in 1900, nobody would have cared either, even if today it would be unthinkable. Perhaps space exploration could become as much a thing that everyone cares about as airplanes are today. It certainly would have to in order to make this plan work.

Overall, it's a pretty radical approach IMHO. What do you guys think - would it work? if not, could it be modified to make it work? (At the end of the interview you can find the author's website and his youtube channel where he goes more in depth about some of his ideas.)

[DAL59]

On 10/18/2017 at 6:17 PM, PB666 said:

intensity of magnetic storms increases.

The dense Venusian air actually results in less radiation in the Venusian upper atmosphere than on the Martian surface.  There's also plenty of solar power for active shielding.  

On 10/18/2017 at 6:17 PM, PB666 said:

rotating ship

ISS tours are about the same length as a mission to Mars/Venus airship would be.  The astronauts take a while to get back to peak physical strength, but they don't die upon return.  On Mars, the recovery would be much easier, given the low gravity.  Especially with the faster transit times offered by the ITS, artificial gravity en route is not necessary at all.  

On 10/18/2017 at 6:17 PM, PB666 said:

r. So lets just say a launch rocket about 5 times the size of a SaturnV rocket.

ITS with orbital refueling

 

[PB666]

And who exactly is going to build and test the floating venutian ship. The trip to Venus exposes the crew to more radiation than ISS, the earths magnetic field takes about half of the radiation and travelers to venus on average would be exposed to 3 times as much radiation. As a consequence to get to Venus they would have to be able to do so in about 4 earth months. In addition Venus has no magnetic field like earth, it has no moons. There is no protection when astronauts get there.

Colonies on mars are doable, just incredibly expensive and suicidal (that is the risk of death each year increases 10 fold that of earth). Reaching the venutian cloud level is simply insane.

[DAL59]

22 hours ago, PB666 said:

risk of death each year increases 10 fold that of earth

[citation needed]

22 hours ago, PB666 said:

earths magnetic field takes about half of the radiation

It is important to distinguish between constant radiation from the sun(blockable by fuel tanks or just plain water), radiation from GCRs(practically unblockable, LEO just blocks half due to occlusion of sky by the Earth), and solar storms(you can have a small storm shelter).

 

The radiation from GCRs wouldn't change whether you are going to Mars or Venus.  In fact, GCR would be less due to shorter transit time.

Edited October 23, 2017 by DAL59

[PB666]

5 hours ago, DAL59 said:

[citation needed]

It is important to distinguish between constant radiation from the sun(blockable by fuel tanks or just plain water), radiation from GCRs(practically unblockable, LEO just blocks half due to occlusion of sky by the Earth), and solar storms(you can have a small storm shelter).

 

The radiation from GCRs wouldn't change whether you are going to Mars or Venus.  In fact, GCR would be less due to shorter transit time.

Risk of death is increased due to the effects of lack of gravity, exposure to radiation, the risk of being 'spaced' by micrometeor collisions or system failures, the risk of starvation, the risk of acquiring a disease that is treatable on earth but not in space, the risk of going technically blind and the consequences thereof . . . . . . . . . Space aint Oslo.

[tater]

I don't think the human factors are insurmountable for long term habitation in space, but I agree with @PB666 that it's non-trivial, and usually overlooked or treated less seriously than it deserves.

Assuming for the sake of argument that medical care, rad shielding, reliable or self-repairable life-support, and all the other basic factors for survival are given, we still have exactly no idea what 0.38g does to people long term, or from an embryological POV.

Sending people to visit is worthwhile, just because it expands the human spirit. Sending people to live? First spin some habs in LEO, and see what 0.38 does to people. Since there is some effective gravity in that experiment, we can then also make sure to test multiple generations of other mammals to see how they fare in reproduction, etc.

[Helmetman]

It's pure speculation because we don't know what 0.38g does long term.

But I don't think it matters much. I think the biological mechanisms of the body adapt to other magnitudes of gravity, always.

I do think that the body will have a much harsher task re adapting to 1g if lower g environments are maintained for decade(s)

If it's really damaging physiologically I can imagine there is a gravity ring in Mars orbit that rewires the body over the course of months by starting in 0.38g and slowly spinning up to 1g for spacefarers willing to go home.

I'm pretty sure it's all about adaptation rather then 'actual' irrecoverable physiological damage during long term low g exposure. But we'll see what this science will further learn us in the future.

 

[PB666]

On 10/6/2017 at 11:14 AM, GreenWolf said:

Planets are a distraction.

I expect all of you are familiar with the extreme delta-v requirements necessary for landing or launching something on a planet.So I'm going to pose this question:

If you have the technology to create a closed-cycle life support system that is self-sustaining (or needs only a relatively small amount of occasional materials inputs) and capable of indefinitely supporting human habitation in space, why would you go to the trouble of building it on the surface of another planet, which would require you to haul everything up and down two gravity wells and across vast interplanetary distances?

Gravity? Well, Mars doesn't have very much of that in the first place, and it's trivial to build a counter-weight and tether system to provide centrifugal gravity.

Minerals? Maybe, but anything you can get from Mars, you can get far more easily from asteroids. In fact, there's a lot of things you can get from asteroids that you can't get from Mars, like phosphorus.

Water? Same deal as before, get your ice from comets and asteroids.

Radiation shielding? Here Mars has a slight advantage, in that it has more space available to put stuff beneath several meters of rock. But it's not too hard to add some layers of shielding to a spacecraft. If you really want to go the distance, you can hollow out an asteroid and use that as your living space.

 

There is nothing on Mars or which can be provided by Mars that cannot be obtained more easily from small-mass asteroids. Colonizing planets is a foolish distraction, the idea of which is only kept alive by naive romanticism. We should be focusing on building arkships and asteroid habitats, which pose far fewer engineer challenges and have the added benefit of being mobile. (Or mobile enough that we could set one [or two, or three, or a hundred] up to slowboat out of the solar system, thereby ensuring the continued survival of the human species, even if, say, a gamma ray burst scoured the life from every planet in the system.)

TL;DR: Mars ain't the kind of place to raise a kid.

Agreed, the dreamy-eyed Mars and Venus colonization dreams are just that.

But to address one issue. If we come up with a constant t_k where t_k is the time each day dealing with the effects of low gravity on the human body. Here on earth t_k = 16 hours per day and since we are out of bed 16 hours a day walking around at 9.8 g then our bodies do not need to set aside time to deal specifically with gravity we can create a metric of 9.8m/s² x 43200 sec/day or 4.9m/s² (averaged over a day). Mars has a gravity of 0.376 is a person works 8 hours per day that gives the person  1.222. This means they only spend 9 hours in the gravity machine to get the same quota as earth. In zero gravity they would have to spend 12 hours a day and then 4 hours working at zero gravity.

A second issue is that construction is one hell of alot easier with some gravity versus zero gravity. The earth itself (or mars) is a foundation for all buildings, it provides traction, friction, a hard place to provide force against.

A third issue is that water on mars is trapped on the surface and you apply force to get it out of its trap, given the preexisting colony on mars extractin water from martian soils in and of itself is expensive, but doable.. On asteroids water is not as abundant and on comets its abundant but its incredible unstable (as the recent asteroid landing mission shows) and most comets apogees require more dV than landing on Mars. If you land on an asteroid you have to bring your own hydrogen with you. Oxygen can be extracted from the metal salts. And for those who think we can extract hydrogen from space, the level of proton in space at 150,000,000 km from the sun is a factor of 1 billion of what we need to be to extract. There is a way to overcome the problem, take a comet, wrap it in a non-breathing material (and shield the sun expose side) and force it into an asteroid with a low relative dV. Now you have volatiles and solids, you can do something. Keep the asteroid side always sunfacing (tidally locked) and the comet side anti-locked. To do this we need an energy source of a way we currently don't have, because comets reside in the part of the system with </14th the sunlight that earth has. Solar panels produce 135 watt for 1 meter panel, at best 135 W/ kg of panel. The energy density require to move a comet down to earths orbit needs to be at least 2 magnitudes higher.

YOu could move a asteroid into a comets orbit (again dV from earth is an issue) and once again we have the issue of a higher wattage density power plant. While comets provide a readily usable ejection mass, some manipulation of asteroid will have to be done (e.g. purifying magnesium or manganese).

The correct way to think about the problem is How do you provide humans with proper radiation shielding and proper gravimetric exposure while simultaneously providing the opportunity to build a colony. If a martian colony is built into the surface and if only they need the surface as an energy source, and they can work at least 6 hours a day at martian gravity and some other hours in a centrifuge then it does seem to be easier.

But if we ask the question, humans are to explore X. Yeah X should be a roid whose orbit is most similar to earths.

 

 

 

 

Edited October 25, 2017 by PB666

[Kerbal7]

1 hour ago, PB666 said:

Agreed, the dreamy-eyed Mars and Venus colonization dreams are just that.

What you said, 100%. I highly doubt even any manned Mars mission will ever take place. Hmmm, 5% chance. And if one does it will be by China and for political reasons.  

[tater]

Some art to browse:

http://www.humanmars.net/p/mars-colony-art.html

 

[JucheJuiceMan]

Saturn Vs were built in 1960's... If we humans werent such petty selfish being we would have been able to mass produce SLVs capable sending 100-150t into LEO.

Our best chance is anyway a space elevator, a one century project.

[tater]

No.

[DAL59]

Yes.  

There were plans to use the Saturn V to sent a manned mission to Mars.  It takes equal delta-vee.  

We already have carbon nanotubes, and synthesizing speeds keep improving.  A orbital tether might be better.  

[Bill Phil]

1 minute ago, DAL59 said:

Yes.  

There were plans to use the Saturn V to sent a manned mission to Mars.  It takes equal delta-vee.  

Yeah, but that would've been EOR. The Saturn V could only send about 45 tonnes to TLI, somewhat less to a Mars transfer. The plan, as laid out in the late 60s, was to use the Saturn V to build a large, essentially multi-stage, vehicle using nuclear thermal propulsion. Actually two of them, although that wouldn't have panned out, even if they had gone for it. Besides, a new lander would've been needed. A Mars landing takes twice the delta-v as a Moon landing, and the LM was too fragile, and it may not have produced enough thrust.

[DAL59]

Even with only chemical propulsion, an EOR Saturn V mission would have been possible.  If the SLS didn't have to

build a DSG, Zubrin calculated it could do a two launch manned Mars mission.

On 10/25/2017 at 2:01 PM, PB666 said:

should be focusing on building arkships and asteroid habitats

I agree that maybe 3/4 of space colonies will be orbital O'neill colonies.  (You can't just spin up an asteroid though.(They break apart.))

However, planets are still useful, because you have abundant resources all in one place, plus natural gravity, and no danger of running out of fuel for mobility.   

[tater]

A 2 Saturn V manned Mars mission is insane. Zubrin can muse all he likes, I'd not see him volunteering for a few years pooping in zip bags in a single room with a few other people.

No way.

Edited October 30, 2017 by tater

[kerbiloid]

Spoiler

4 hours ago, tater said:

I'd not see him volunteering for a few years pooping in zip bags in a single room with a few other people.

 

[JucheJuiceMan]

MIR and ISS are proof of ability to assemble relatively  large objects in LEO, today we have technilogy to build lighter and stronger airframes while also mastering controled recovery of first soon seconf stage of SLVs.

Alternative is using magnetic rails to propel objects to LEO.

The best and most long term option is to build space elevator to simplify logistics and to have viable way of delivering resources from asteroids and moon.

[PB666]

15 hours ago, DAL59 said:

[snipped]

That quote is not from me, I don't know where you got it from. I am not in favor of Arkships (this is something now best handled by molecular biology and biotechnology). 

Be more careful before you attribute material.

[kerbiloid]

Why not build a launchpad on the Everest and an elevator to deliver rockets?
It's near equator (more or less), it's above the atmosphere.

[PB666]

Everest is not ideal. No air.

 

[Hay]

18 minutes ago, kerbiloid said:

Why not build a launchpad on the Everest and an elevator to deliver rockets?
It's near equator (more or less), it's above the atmosphere.

Extremely expensive.

[tater]

Not to mention a few people living down range who might not like boosters falling on their houses.

Edited October 30, 2017 by tater

[kerbiloid]

39 minutes ago, Hay said:

Extremely expensive.

For small rockets - yes.

4 minutes ago, tater said:

Not to mention a few people living down range who might not like boosters falling on their houses.

There are many Everest-high mountains, and usually they are not overpopulated.