High School Survival on Mars: Radiation & Temperature Challenges

[GTOM]

What is the average frequency of dust storms?

 

[Generator Gawl]

Mars definitely has winds. They can kick up dust storms which, from time to time, cover the whole planet for weeks at a time. Mars was in the middle of the largest one ever recorded in 1971 when Mariner 9 arrived. NASA had to wait a couple of months for it to clear before they could get images of the surface.

Do you think that is the reason for exposed regolith? Maybe the dust top layer was blown off over the eons, exposing the hard and compact lower layer of rock and then eroding that into the fine dust that we see settling on top. Just off the top of my head.

 

[marcus]

Trivial. Mars has no "soil". It has regolith.

In most places where humans live, you have dig a rather deep hole through the soil before you hit regolith. Soil on the Earth is chock full of organisms, most of which are very, very small. Humanity is still learning about the extreme importance of those microbes in the soil to the plants that grow in the soil.

To help with the definition of terms, so we can be on the same page:
https://en.wikipedia.org/wiki/Regolith
==quote==
Regolith is a layer of loose, heterogeneous superficial material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestrial planets and moons.
==endquote==

So regolith occurs on Earth and it includes SOIL. Soil is therefore a type of regolith. You do not need to dig a hole to "hit regolith". DUST is also a type of regolith and can be distinct from soil. Let's look up soil and see what is special about the type of regolith called soil. Probably it has to do with the inclusion of organic material. Would volcanic ash, alluvial gravel, or desert sand (especially if extremely dry and nearly free of organic substances) always be considered "soil"? Or would it simply be classified as (a non-soil type of) regolith?
Here's from the Wikipedia "Soil" article:
===quote https://en.wikipedia.org/wiki/Soil ===

A represents soil; B represents laterite, a regolith; C represents saprolite, a less-weathered regolith; the bottom-most layer represents bedrock.
===endquote==
So Earth has layers of non-soil regolith. If you strip off the top layer, remove the soil-type regolith you may find other layers of unconsolidated material which are classified as regolith.

So I would expect there are places on Earth where soil has been removed, which are bare non-soil regolith. Or where because of extreme environment soil has not formed.

 

[marcus]

Do you think that is the reason for exposed regolith? Maybe the dust top layer was blown off over the eons, exposing the hard and compact lower layer of rock and then eroding that into the fine dust that we see settling on top. Just off the top of my head.

A dust layer would qualify as regolith. If it is not covered by some other layer it is exposed. So it would be exposed regolith.
The term was introduced in 1897
==quote https://en.wikipedia.org/wiki/Regolith#Etymology ==
The term regolith combines two Greek words: rhegos (ῥῆγος), "blanket", and lithos (λίθος), "rock". The American geologist George P. Merrill first defined the term in 1897, writing:

"In places this covering is made up of material originating through rock-weathering or plant growth in situ. In other instances it is of fragmental and more or less decomposed matter drifted by wind, water or ice from other sources. This entire mantle of unconsolidated material, whatever its nature or origin, it is proposed to call the regolith.[1]"
==endquote==

== https://en.wikipedia.org/wiki/Regolith#Earth ==
Earth's regolith[2][3][4] includes the following subdivisions and components:

• soil or pedolith
• alluvium and other transported cover, including that transported by aeolian, glacial, marine, and gravity flow processes.
• "saprolith'", generally divided into the
  • upper saprolite: completely oxidised bedrock
  • lower saprolite: chemically reduced partially weathered rocks
  • saprock: fractured bedrock with weathering restricted to fracture margins.
• volcanic ash and lavas...

...
...
==endquote==

 

[GTOM]

What are the true colors of Mars? (Regolith, sky, Sun at top and at sunset)
My problem is, that many photos have false colors, that can be confusing.

 

[mfb]

The surface appears mainly reddish, and the Mars rovers have some realistic images. The sky is more complicated due to the Purkinje effect, see the Wikipedia article about the Martian sky view.

 

[GTOM]

The surface appears mainly reddish, and the Mars rovers have some realistic images. The sky is more complicated due to the Purkinje effect, see the Wikipedia article about the Martian sky view.

Thanks. It is weird to me, how the vicinity of Sun becomes blue? Even if scattering is so weak, how does thick air swallow or scatter more red, when the rusty dust reflects red and swallows blue?

 

[mfb]

If the particles are small enough, they just let blue pass through while red is still scattered (at the level of molecules, not due to the size of the dust).

 

[my2cts]

I do not see why anyone in his right mind would want to live on Mars. Recently I flew over Australia. Lots of emptyness there.

 

[Neon]

I don't see any trouble in warming Mars since we are experts at it. I read nuking Mars at the ice caps to release CO2 methane water .But radiation and radioactive stuff from the nuke is bad.Just it needs a magnetic field is hard.

 

[_PJ_]

Sending probes and unmanned vessels to setup the basis for a hardy plant-life to take hold and photosynthesize some oxygen and generate a nit
rogen cycle, soil and recycle some polar ice, then when it's essentially taken hold after a few millennia, whatever status of mankind may be technologically able to travel there safely to begin a hands-on terraforming.

 

[marcus]

Since we just turned a page, here for continuity are the last three posts.

I do not see why anyone in his right mind would want to live on Mars. Recently I flew over Australia. Lots of emptyness there.

I don't see any trouble in warming Mars since we are experts at it. I read nuking Mars at the ice caps to release CO2 methane water .But radiation and radioactive stuff from the nuke is bad.Just it needs a magnetic field is hard.

Sending probes and unmanned vessels to setup the basis for a hardy plant-life to take hold and photosynthesize some oxygen and generate a nitrogen cycle, soil and recycle some polar ice, then when it's essentially taken hold after a few millennia, whatever status of mankind may be technologically able to travel there safely to begin a hands-on terraforming.

 

[D H]

I don't see any trouble in warming Mars since we are experts at it.

While we collectively may have warmed the Earth a bit (and will continue to do so), we are not "experts" at this. We have accomplished this by pure bungling. That expertise does not carry forward to Mars. We haven't the foggiest idea how to warm Mars.

I read nuking Mars at the ice caps to release CO2 methane water. But radiation and radioactive stuff from the nuke is bad.

That was Bored Elon Musk speaking. It was not a serious proposal. Do the math. Hundreds of Tsar Bomba (the largest bomb ever built) equivalents would have very little effect with regard to releasing CO₂ and H₂O at the Mars ice caps. With regard to methane, there isn't much on Mars.

Releasing all of the CO₂ at Mars' ice caps into Mars atmosphere will not do much to help Mars warm up. Mars' atmosphere is almost entirely CO₂. Increasing that by another 25% won't do much (about a third of Mars' CO₂ is in its ice caps). Think of it this way: We are concerned with a doubling of CO₂ in the Earth's atmosphere from pre-industrial levels. The current consensus is that this will result in a 1.5° to 4.5° increase (Celsius) annual average temperature by the end of this century. A 25% increase in Mars' CO₂ atmospheric content will result in an even smaller increase. Mars needs to get a lot warmer than a mere 1.5° to 4.5° to become habitable.

Just it needs a magnetic field is hard.

Scientists go back and forth on how important a role magnetic field plays in a planet retaining its atmosphere. The current thinking appears to be that it is secondary, at best. Far more important are mass and distance from the Sun. Venus and Titan both have very thick atmospheres, much thicker than the Earth's, but neither has a significant magnetic field. With Venus, it's mass that counts. With Titan, it's distance from the Sun. Mars is too close to the Sun for a planet that small to hold a significant atmosphere for a geologically significant length of time.

Mars doesn't need to hold an atmosphere for a geologically significant length of time to be habitable. It merely needs to hold onto that atmosphere for a humanly significant length of time. A few hundred thousand years is but an instant geologically, but it is an extremely long span of time as far as humans are concerned.

 

[mfb]

Mars doesn't need to hold an atmosphere for a geologically significant length of time to be habitable. It merely needs to hold onto that atmosphere for a humanly significant length of time. A few hundred thousand years is but an instant geologically, but it is an extremely long span of time as far as humans are concerned.

Well, do you want to sublimate all the ice caps if you expect to lose the resulting CO2 to space forever within hundred thousand years?
Okay, chances are good it would be done if it gives some short-term benefit...

We had a link to a study recently, but I don't find it now. Increasing the CO2 in the atmosphere would raise the temperature, which then would help releasing more CO2. A study suggested that the initial amount needed to start that process could be a small fraction of the ice caps, resulting in a different stable state.

 

[DHF]

When Musk proposed nuking Mars, his comments really should have been accompanied by a rimshot.
Nuking the planet to make it habitable is like burning your house down because it is messy.

Even if it somehow made sense, you would need an ungodly amount of money to transport that make warheads to Mars as well as a magic wand to convince the government to let go of that much firepower.

 

[GTOM]

When Musk proposed nuking Mars, his comments really should have been accompanied by a rimshot.
Nuking the planet to make it habitable is like burning your house down because it is messy.

Even if it somehow made sense, you would need an ungodly amount of money to transport that make warheads to Mars as well as a magic wand to convince the government to let go of that much firepower.

Redirecting a large asteroid means less pollution, although based on the answers, I'm still skeptical.

 

[Loren]

Let's not forget that the soil is also poisonous. It contains perchlorate, which is going to be a jerk to keep out of living habitats.

I guess the sale of Dust Devils will soar on Mars.

 

[GTOM]

Scientists go back and forth on how important a role magnetic field plays in a planet retaining its atmosphere. The current thinking appears to be that it is secondary, at best. Far more important are mass and distance from the Sun. Venus and Titan both have very thick atmospheres, much thicker than the Earth's, but neither has a significant magnetic field. With Venus, it's mass that counts. With Titan, it's distance from the Sun. Mars is too close to the Sun for a planet that small to hold a significant atmosphere for a geologically significant length of time.

Mars doesn't need to hold an atmosphere for a geologically significant length of time to be habitable. It merely needs to hold onto that atmosphere for a humanly significant length of time. A few hundred thousand years is but an instant geologically, but it is an extremely long span of time as far as humans are concerned.

I don't doubt what they say, just sounds strange to me, if magnetic field isn't the key, i would think, with 1/3 g and lower radiation, it would be only 3 times more thin as Earth. Could you link something that explain some details?

 

[Supr4]

Let's not forget that the soil is also poisonous. It contains perchlorate, which is going to be a ***** to keep out of living habitats.

I guess the sale of Dust Devils will soar on Mars.

True. I found an article that seems interesting. It suggests a a biochemical approach to reducing the toxicity of the soil.
Here: http://www.space.com/21554-mars-toxic-perchlorate-chemicals.html

In the short(er) term, it'd probably be best to either use cleaning areas in Mars modules for suits and equipment, or have space suits mounted to external/uncontrolled areas of a Martian habitat.Possibly like this? (Credit: NASA - Moonbase Alpha)

 

[Loren]

True. I found an article that seems interesting. It suggests a a biochemical approach to reducing the toxicity of the soil.
Here: http://www.space.com/21554-mars-toxic-perchlorate-chemicals.html

In the short(er) term, it'd probably be best to either use cleaning areas in Mars modules for suits and equipment, or have space suits mounted to external/uncontrolled areas of a Martian habitat.Possibly like this? (Credit: NASA - Moonbase Alpha)

That would be a good idea.

 

[mfb]

I don't doubt what they say, just sounds strange to me, if magnetic field isn't the key, i would think, with 1/3 g and lower radiation, it would be only 3 times more thin as Earth. Could you link something that explain some details?

Why do you expect a linear relationship between g on the surface and atmospheric pressure?

Without solar wind, the key quantity is the average kinetic energy of the molecules (in the upper atmosphere) compared to the energy necessary to escape from the planet. The escape velocity is about 5 km/s for Mars, for Earth it is 11.2 km/s.

Let's take Earth: T=2000 K, E=3/2 kT = 250 meV (the hot temperature is driven by solar radiation).
The necessary energy to escape for Helium is ##\frac{1}{2} m_{He} v^2_{esc} = 2.6 eV = 10.4 * 250 meV.
While it is rare, some helium atoms will get 10 times their average energy (and move upwards), and escape. Over geological timescales, most helium atoms escape.
Elementary nitrogen needs 3.5 times this energy, or ~35 times the average energy. That is really rare. Molecular nitrogen needs even more energy.

=> on Earth, helium escapes, but nitrogen does not (not including effects of solar wind).

 

[GTOM]

Why do you expect a linear relationship between g on the surface and atmospheric pressure?

Without solar wind, the key quantity is the average kinetic energy of the molecules (in the upper atmosphere) compared to the energy necessary to escape from the planet. The escape velocity is about 5 km/s for Mars, for Earth it is 11.2 km/s.

Let's take Earth: T=2000 K, E=3/2 kT = 250 meV (the hot temperature is driven by solar radiation).
The necessary energy to escape for Helium is ##\frac{1}{2} m_{He} v^2_{esc} = 2.6 eV = 10.4 * 250 meV.
While it is rare, some helium atoms will get 10 times their average energy (and move upwards), and escape. Over geological timescales, most helium atoms escape.
Elementary nitrogen needs 3.5 times this energy, or ~35 times the average energy. That is really rare. Molecular nitrogen needs even more energy.

=> on Earth, helium escapes, but nitrogen does not (not including effects of solar wind).

Thanks. Theoretically, could Mars hold a thicker atmosphere, if it were made of heavier molecules? (nitrogen-oxids, ethane for example) Although it were still unbreathable, but less problem of cold, and lack of pressure.

 

[Neon]

Methane would be good i guess.And can perhaps burn it for lost of co2

 

[mfb]

Methane is one of the lightest gases after hydrogen and helium.
Also, everything with hydrogen is problematic because sunlight can break up those molecules, and free hydrogen escapes easily.

CO2 is quite heavy, and still around on Mars.

 

[Dotini]

A deeply pessimistic assessment of manned missions to Mars:
Testimony to congress from John Sommerer, chairman of the Technical Panel of the National Research Council Committee on Human Spaceflight.
http://spaceref.com/news/viewpr.html?pid=47821

 

[nikkkom]

A deeply pessimistic assessment of manned missions to Mars:
Testimony to congress from John Sommerer, chairman of the Technical Panel of the National Research Council Committee on Human Spaceflight.
http://spaceref.com/news/viewpr.html?pid=47821

"The psycho-social limits on a small group of astronauts confined to extremely tight quarters for multiyear periods, without possibility of real- time interaction with family and friends, pose another poorly understood threat to crew safety and mission success."

This guy forgot that we have these things on Earth called "prisons". Nelson Mandela spent some 26 years in prison, IIRC. For most of that time, he didn't know whether he would ever be free again. His sanity survived that.

 

[mfb]

Prisons have way more space, (usually) way more other persons around, and usually allow contact to family and friends.
On the other hand, people rarely go there voluntarily, they don't go there for research, and they are not as busy as astronauts are.

We have experiments on Earth investigating the social and psychological effects a crew to Mars would encounter. Increasing the sample size would be a small fraction of the overall costs of a manned Mars program.

The report seems to be this one, or a variation of it.

 

[nikkkom]

Prisons have way more space

Maybe US prisons do. I assure you, my country's prisons do not.

(usually) way more other persons around

...a number of which are such that you would rather NOT see them around you...

, and usually allow contact to family and friends.

You again base it on US prisons. :D

On the other hand, people rarely go there voluntarily, they don't go there for research, and they are not as busy as astronauts are.

And they do not get to become historically famous people who settled the first ever human colony on another planet.

 

[D H]

"The psycho-social limits on a small group of astronauts confined to extremely tight quarters for multiyear periods, without possibility of real- time interaction with family and friends, pose another poorly understood threat to crew safety and mission success."

This guy forgot that we have these things on Earth called "prisons". Nelson Mandela spent some 26 years in prison, IIRC. For most of that time, he didn't know whether he would ever be free again. His sanity survived that.

What you have done is unacceptable.

You have accused @mfb is being an American and being biased because of that. That is rude and incorrect. All it takes is one look at mfb's profile page. mfb is not an American.

You have claimed that Nelson Mandela's tiny little prison shows that this testimony is wrong. In doing so, you have discounted the immense number of studies by the US, the Soviet Union, Great Britain, and any other country that has submarines that show that people do not behave rationally when isolated for a long duration. The psychological investigations into the people who want to serve on a submarine is quite intrusive and intense.

For every one Nelson Mandela, there are thousands and thousands of prisoners who come out of prison scarred for life. BTW, Nelson Mandela had 2.4 meter by 2.1 meters by 2 meters of living space in prison. That's 10 cubic meters, for one person. The Orion capsule has about 9 cubic meters of living space, and that's supposedly for a crew of six.

Worst of all, you have ignored all of the other things in that testimony that says that sending humans to Mars and back is but a pipe dream.

 

[Chronos]

Spending a long time in cramped quarters is not fun and provokes enduring psychological issues. A mission to Mars would land a menagerie of psychologically impaired people in a hostile. alien environmnet. That is a recipe for disaaster, IMO.