Author Topic: Quickly making an atmosphere on Mars by crashing a comet  (Read 34358 times)

Offline Elmar Moelzer

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #20 on: 10/01/2015 09:03 am »
But some people say... no, they *demand* that human Mars landings must be perpetually banned not just because we may kill existing poor oppressed Martian bacteria with our evil racist white male supremacist Earth bacteria. No. Even if Mars has no life today, we must avoid landing because
(wait for it)
it may develop life many million years in the future!!!
Yeah, I have talked to people with such concerns. TBH, I don't care. I wont lose any sleep over a few microbes. I kill millions of them all the time. I am more worried about what they could do to us or our equipment and already sparse resources. Both are things that microbes are quite good at.
Other than that, Mars is there for the taking, lets take it!

Offline Stormbringer

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #21 on: 10/01/2015 02:57 pm »
There is probably going to be some serious resistance to doing this on biology and environmental grounds. Even basic terraforming activities could arguably destroy any remaining lifeforms or evidence thereof.
What lifeforms?
So far all we have evidence for that there are none. The biggest issue I would have with remaining martian life forms is the potential (unknown) hazard they could pose to people and equipment.

I dunno- but it's not just radical environmentalist kookazoids stating objections like this. The space powers and organizations are trying to develop bio-security protocols to prevent contamination of places we land probes and eventually space ships on. But...we have a 1 meter cloud of floating flora and fauna around each and everyone of us. It does not matter if you suit up. your personal managerie is still floating around the crew space. You don't have to drop trou- and take a dump on the surface as amusing as that misadventure might turn out. notwithstanding; stuff like that gets left behind when the ascent module leaves. It did on the moon landings if i recall; and microbes are allegedly munching away on the Viking lander's insulation right now. I think I read that somewhere.
When antigravity is outlawed only outlaws will have antigravity.

Offline Elmar Moelzer

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #22 on: 10/02/2015 01:30 am »
I dunno- but it's not just radical environmentalist kookazoids stating objections like this. The space powers and organizations are trying to develop bio-security protocols to prevent contamination of places we land probes and eventually space ships on.
Yes, but to my best understanding this is mainly for the purpose of preventing false results from contaminated samples. It would be quite silly if we tricked ourselves into finding earth like microbes on mars (and potentially making wrong "panspermia" conclusions from that) because we actually introduced these microbes ourselves.
But, I presume that by the time we begin terraforming mars, this wont be a topic anymore.

Offline Hop_David

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #23 on: 10/04/2015 08:04 pm »
So I was just doing some browsing of Wikipedia and found the following:

https://en.wikipedia.org/wiki/Halley%27s_Comet

Halley's comet has a mass of 10^14 kg. Because it has a retrograde orbit, it passes Earth (and Mars) at about 71 km/s or 71 000 m/s.

The mass of Mars' northern polar cap contains 1.6 million km^3 of ice (30% of which is CO2).

https://en.wikipedia.org/wiki/Mars

This equates to 1.1 x 10^15 m^3 of ice, or (1.1 x 10^15 m^3)(1000 kg/m^3) = 1.1 x 10^18 kg of ice. To turn this into a liquid you would need (330 000 J/kg)(1.1 x 10^18 kg) = 3.6 x 10^23 J.

The amount of CO2 if sublimed would be enough to make a 1 atm atmosphere:

assume an atmosphere 10 000 m high, it would have a volume of 4(pi)(3.4 x 10^6 m^2)(10 000 m) =
1.5 x 10^17 m^3

For a 10 kilometer thick spherical shell covering Mars, I get a volume of 1.45 e18 cubic meters.

Moreover, with Mars' lower gravity, scale height is 264% that of earth given atmosphere of comparable temperature and composition. A column of air would extend much higher than 10 kilometers.

I took a look at Mars terraforming.

Offline Hop_David

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #24 on: 10/04/2015 08:21 pm »
Halley's comet has a mass of 10^14 kg. Because it has a retrograde orbit, it passes Earth (and Mars) at about 71 km/s

When in Mars' neighborhood it's moving a little slower. It be about 57 km/s wrt Mars.

Something to consider with large, high speed impactors is atmospheric erosion

Quote
The impact of a large meteoroid can lead to the loss of atmosphere. If a collision is energetic enough, it is possible for ejecta, including atmospheric molecules, to reach escape velocity.

In extreme cases all the atmosphere above the tangent plane at point of impact is blasted away. As well as most of the cometary volatiles and some of the frozen volatiles at the impact site.

Offline Elmar Moelzer

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #25 on: 10/04/2015 10:55 pm »
In extreme cases all the atmosphere above the tangent plane at point of impact is blasted away. As well as most of the cometary volatiles and some of the frozen volatiles at the impact site.
Hmm, seeing that extinction level event asteroid impacts on earth have occurred rather frequently I have to wonder whether those had any impact on the density of earths atmosphere.

Offline Hop_David

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #26 on: 10/04/2015 11:33 pm »
In extreme cases all the atmosphere above the tangent plane at point of impact is blasted away. As well as most of the cometary volatiles and some of the frozen volatiles at the impact site.
Hmm, seeing that extinction level event asteroid impacts on earth have occurred rather frequently I have to wonder whether those had any impact on the density of earths atmosphere.

Earth has a thicker atmosphere and a deeper gravity well than Mars so is less vulnerable to atmospheric erosion. But Chicxulub might have splashed some of our atmosphere out of our Hill Sphere.

Offline Admiral_Ritt

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #27 on: 10/07/2015 09:13 pm »
 First Time Poster, Here:

Crashing a few comets will not solve the basic Problem,  for the following reasons.

1) Mars orbit is too far from the sun to keep ANY portion of mars above Freezing point, even with
a 1% CO2 in a 500 mb atmosphere.  People forget how mild a Green House gas CO2 is.   The only
time the earth CO2 levels had an overwhelming impact was when it ended the great ice ball event.  This was caused  by the CO2 levels rising to 10%. and resulted in the end of the great glaciation event.   Mars does not have a CO2 (Trapped in rocks or where ever) reservoir that large.


2) while it would raise the MB levels to where water would flow,  it would not last.  The particulates
in the atmosphere will block the sun light,  and initiate a global winter once the initial heat of the impact dissipates, and once again the atmosphere will freeze out.   it would take a few years but that is a certainty.

3)  If you continually crashed smaller comets to keep the temperature up,  the resulting global atmospheric shock wave would necessitate that any surface infrastructure would be destroyed.

4)   This would not solve the lack of magnetic field,  and the surface while temporarily allowing some shirtsleeve
operations (with a respirator no doubt)  you will still need to live underground in caves that are pressurized.

 If you had access to compact cheap portable energy source, then Titan would be a superior colonization
location.   No radiation, Plenty of organics, easy access from  surface to orbit (assuming you can get there)
You would have to live in Ice Caves, but at least you could go outside with more modest protection,  (using a heated inner suit, you could wear modest winter gear on the outside with a respirator.   Try that on Mars.



Offline Alf Fass

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #28 on: 10/07/2015 10:05 pm »
First Time Poster, Here:

Crashing a few comets will not solve the basic Problem,  for the following reasons.

1) Mars orbit is too far from the sun to keep ANY portion of mars above Freezing point, even with
a 1% CO2 in a 500 mb atmosphere.  People forget how mild a Green House gas CO2 is.   The only
time the earth CO2 levels had an overwhelming impact was when it ended the great ice ball event.  This was caused  by the CO2 levels rising to 10%. and resulted in the end of the great glaciation event.   Mars does not have a CO2 (Trapped in rocks or where ever) reservoir that large.


2) while it would raise the MB levels to where water would flow,  it would not last.  The particulates
in the atmosphere will block the sun light,  and initiate a global winter once the initial heat of the impact dissipates, and once again the atmosphere will freeze out.   it would take a few years but that is a certainty.

3)  If you continually crashed smaller comets to keep the temperature up,  the resulting global atmospheric shock wave would necessitate that any surface infrastructure would be destroyed.

4)   This would not solve the lack of magnetic field,  and the surface while temporarily allowing some shirtsleeve
operations (with a respirator no doubt)  you will still need to live underground in caves that are pressurized.

 If you had access to compact cheap portable energy source, then Titan would be a superior colonization
location.   No radiation, Plenty of organics, easy access from  surface to orbit (assuming you can get there)
You would have to live in Ice Caves, but at least you could go outside with more modest protection,  (using a heated inner suit, you could wear modest winter gear on the outside with a respirator.   Try that on Mars.


Agree with what you say about Mars. Regarding Titan, The cyanide could be a problem.
When my information changes, I alter my conclusions. What do you do, sir?
John Maynard Keynes

Offline Elmar Moelzer

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #29 on: 10/08/2015 06:09 pm »
Kinda fits into the discussion:
http://gizmodo.com/ancient-mars-was-wetter-and-warmer-than-we-ever-realize-1735453913?utm_campaign=socialflow_gizmodo_facebook&utm_source=gizmodo_facebook&utm_medium=socialflow

Unfortunately the actual paper is behind a paywall, which is why I can only post the link to this synopsis here.
« Last Edit: 10/08/2015 06:10 pm by Elmar Moelzer »

Offline Solman

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #30 on: 10/08/2015 10:22 pm »
First Time Poster, Here:

Crashing a few comets will not solve the basic Problem,  for the following reasons.

1) Mars orbit is too far from the sun to keep ANY portion of mars above Freezing point, even with
a 1% CO2 in a 500 mb atmosphere.  People forget how mild a Green House gas CO2 is.   The only
time the earth CO2 levels had an overwhelming impact was when it ended the great ice ball event.  This was caused  by the CO2 levels rising to 10%. and resulted in the end of the great glaciation event.   Mars does not have a CO2 (Trapped in rocks or where ever) reservoir that large.


2) while it would raise the MB levels to where water would flow,  it would not last.  The particulates
in the atmosphere will block the sun light,  and initiate a global winter once the initial heat of the impact dissipates, and once again the atmosphere will freeze out.   it would take a few years but that is a certainty.

3)  If you continually crashed smaller comets to keep the temperature up,  the resulting global atmospheric shock wave would necessitate that any surface infrastructure would be destroyed.

4)   This would not solve the lack of magnetic field,  and the surface while temporarily allowing some shirtsleeve
operations (with a respirator no doubt)  you will still need to live underground in caves that are pressurized.

 If you had access to compact cheap portable energy source, then Titan would be a superior colonization
location.   No radiation, Plenty of organics, easy access from  surface to orbit (assuming you can get there)
You would have to live in Ice Caves, but at least you could go outside with more modest protection,  (using a heated inner suit, you could wear modest winter gear on the outside with a respirator.   Try that on Mars.
[/quote

Welcome to the forum.
As for your first point, It might be helpful if numbers for the total CO2 known to be on Mars were cited particularly the amount frozen at the poles.
As for the second point-wouldn't a Mars with runningwater have rain that would wash particulates out of the atmosphere?
As for small comets creating destructive global shock waves; it seems to me that the minimum size could be quite small since even those that burn up in the atmosphere add heating and gasses but ones that survive and make craters would still only need be a couple hundred feet in diameter particularly if the atmosphere is left at something like 4 psi and almost 100 percent CO2 for shirt sleeve pressure and liquid water. I doubt there would be any large area disturbance.
On a warm shirt sleeve Mars you wouldn't have to live in ice caves but it might be quite a while before you can make it without supplemental oxygen.
As for a magnetic field I remember a previous thread in which a superconducting wire at the equator was suggested.
I think comet crashing makes Mars terra-forming relatively easy but I believe large tropical space colonies so large that they hold atmosphere without needing a roof will be what most humans live in in a couple centuries. Engineered inside out worlds with open sky and perfect climate sound nice to me but YMMV.
As for Titan that would have to be some powerful energy source to warm that cold moon up wouldn't it?
« Last Edit: 10/08/2015 10:31 pm by Solman »

Offline Solman

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #31 on: 10/09/2015 12:25 am »
Sorry about format of previous post. New tablet.

Offline Admiral_Ritt

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #32 on: 10/09/2015 02:50 am »
     Regarding Mars CO2  total abundance.   Reading the literature it turns out that 80% of is frozen at the
Poles.  Mars atmosphere is .6% that of earth.  So if we were to totally heat up all the CO2, (hey by crashing a
comet into it) , you would get somewhere around 2.5% of earth's atmosphere,  and that atmosphere would
consist of 94%  C02.    the unfortunate facts are that mars has no buffering gas to increase it beyond this.  h20
does not count as it is only temporarily a gas until frezes out,  and even it if were to bring the surface presure to
5%, that would not be enough to make a difference.   

There is no where else to get more atmospheric gas,  the crust is mostly bassalt,  with oxydes of  Sodium, Iron Magnesium, potassim, and no  apparent volcanism left.

you second point
True the rain would wash the particluates, but the clouds would reflect a lot sunlight lowering temperatures in
a short time.

I grant that if you smash smaller bits of comets, you will not create a global shockwave of a large magnitude.

I forgot an important strike against mars.  Alot more meteories reach it's surface, and they come in very hot due
to the thin atmosphere.  at  1 cm  meteorite would destroy the rover up there if it hit close.  (a few feet)


Offline scienceguy

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #33 on: 10/09/2015 03:18 am »
      Mars atmosphere is .6% that of earth.  So if we were to totally heat up all the CO2, (hey by crashing a
comet into it) , you would get somewhere around 2.5% of earth's atmosphere,  and that atmosphere would
consist of 94%  C02.    the unfortunate facts are that mars has no buffering gas to increase it beyond this.


What about getting a buffering gas from the comet? Comets have ammonia, and let's not forget about ammonia combustion (the oxygen for which you could get from water on Mars) which yields N2:

4 NH3 + 3 O2 → 2 N2 + 6 H2O (g)
e^(pi*i) = -1

Offline Alf Fass

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #34 on: 10/09/2015 03:41 am »
      Mars atmosphere is .6% that of earth.  So if we were to totally heat up all the CO2, (hey by crashing a
comet into it) , you would get somewhere around 2.5% of earth's atmosphere,  and that atmosphere would
consist of 94%  C02.    the unfortunate facts are that mars has no buffering gas to increase it beyond this.


What about getting a buffering gas from the comet? Comets have ammonia, and let's not forget about ammonia combustion (the oxygen for which you could get from water on Mars) which yields N2:

4 NH3 + 3 O2 → 2 N2 + 6 H2O (g)

You started off this thread suggesting we could "Quickly making an atmosphere on Mars by crashing a comet" into the planet.
To provide Mars with 1atm pressure you'll need a comet, principally composed of the desired volatiles, with a mass of 3600,000,000,000,000 tonnes, if it's as dense as water it'll be 200km in diameter. There's no such object handy.
When my information changes, I alter my conclusions. What do you do, sir?
John Maynard Keynes

Offline scienceguy

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #35 on: 10/09/2015 03:48 am »

You started off this thread suggesting we could "Quickly making an atmosphere on Mars by crashing a comet" into the planet.
To provide Mars with 1atm pressure you'll need a comet, principally composed of the desired volatiles, with a mass of 3600,000,000,000,000 tonnes, if it's as dense as water it'll be 200km in diameter. There's no such object handy.

no, I said that the kinetic energy of a large comet in a retrograde orbit would provide enough energy to melt the polar ice cap. The volatiles mainly come from the polar ice cap, not mainly from the comet.
e^(pi*i) = -1

Offline Alf Fass

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #36 on: 10/09/2015 04:33 am »
Haven't we established that there ain't enough CO2 in the caps?
When my information changes, I alter my conclusions. What do you do, sir?
John Maynard Keynes

Offline scienceguy

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #37 on: 10/09/2015 04:38 am »
Haven't we established that there ain't enough CO2 in the caps?

Fair enough. But I don't think we should abandon this comet crashing idea totally, because as some mentioned, you could get a runaway greenhouse effect with the CO2 you liberate, and if you crash more than one comet you could get a little more volatiles and heating.

edit: don't forget: water is a greenhouse gas too!
« Last Edit: 10/09/2015 04:41 am by scienceguy »
e^(pi*i) = -1

Offline Alf Fass

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #38 on: 10/09/2015 05:56 am »
Haven't we established that there ain't enough CO2 in the caps?

Fair enough. But I don't think we should abandon this comet crashing idea totally, because as some mentioned, you could get a runaway greenhouse effect with the CO2 you liberate, and if you crash more than one comet you could get a little more volatiles and heating.

edit: don't forget: water is a greenhouse gas too!

 Comet impacts could be part of making Mars more habitable, but as has been pointed out, without subsequent management of the planet the debris blasted into the Martian upper atmosphere will only cause the long winter that has followed such impacts on Earth.
When my information changes, I alter my conclusions. What do you do, sir?
John Maynard Keynes

Offline MickQ

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Re: Quickly making an atmosphere on Mars by crashing a comet
« Reply #39 on: 10/09/2015 10:45 am »
If your trajectory brought the comet in on a very low, grazing angle without actually impacting then no, or not much dust thrown into the atmosphere. Problem then is not much heat generated.  Orbiting mirrors and lenses ?

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