"It's a bit chilly today" - Temperatures on Mars

Palomar · 2002-06-01 15:53:50

I'm wondering about the comfort-level of life on Mars, considering how cold it is. I've read that the average *high* temperature (in Fahrenheit) is near the equator, approximately 64 degrees? But doesn't Mars have more of an ellipitical orbit than Earth? Sure, it'll be warm in the habitats and space suits (if someone should want to wander outdoors), but I'm wondering how cold the *warmest* parts of Mars will be when the planet is furthest from the sun in its orbital path.

And what effect will the cold temps have on terraforming (unless vegetable/plant life will always be grown in domes)? If the atmosphere of Mars can be manipulated into becoming more rich and thick -- sounds like coffee...okay, so I'm not a scientist! -- will that warm the planet up a bit?

--Cindy

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Josh Cryer · 2002-06-01 21:51:53

It's gotten up to the seventies, but, this is at surface level. Just a meter off the ground the temperature drops significantly. This is because the air pressure on Mars is a mere 5-10 millibars (compared to 1000 at sea level on Earth). You can't walk around with just a face mask for oxygen, unfortunately.

If you were to thicken the atmosphere, the temperature would definitely go up. Especially if you used CFCs. Robert Zubrin has done extensive research on the subject, you can read his terraforming stuff here:

http://www.nw.net/mars/

Shaun Barrett · 2002-06-02 20:53:49

There's an interesting toy to play with called the "Terraforming Simulator Project", which you can call up on any search engine.
It enables you to enter a number of variables into a program which then calculates the effect on the Martian climate. The variables include millibars of CO2, N2/O2, and microbars of methane, ammonia, and CFCs. It also allows you to vary the amount of insolation (sunlight falling on the surface) and the albedo (reflectivity) of the surface.
What quickly becomes apparent is that, while the amount of CO2 in the atmosphere is important, the effect of small amounts of ammonia and tiny amounts of super greenhouse gases like CFCs is absolutely startling!!
Even with a moderately dense atmosphere of, say, 500 millibars of CO2 and 50 millibars of N2/O2 (leaving insolation and albedo unchanged), tiny amounts of NH3 and CFCs can elevate the Martian global temperature average to 17 or 18 degrees C ! This is enough to keep 90% of the surface, or better, above freezing.
The Simulator is easy to use and comes with a user's guide. Try it ... it's good fun and it's a real eye-opener as to what we can achieve on Mars, sooner rather than later!!

Palomar · 2002-06-04 16:04:51

Josh wrote: "It's gotten up to the seventies, but, this is at surface level. Just a meter off the ground the temperature drops significantly."

*Geez. Just a meter off the ground ::anywhere:: on Mars' surface? I'm wondering if the same holds true for a valley? If not, the colonists would be better off establishing a base in a valley -- ?

--Cindy (not a scientist obviously)

Shaun Barrett · 2002-06-04 21:05:20

Hi Cindy!
I think Josh refers only to near-equator regions when he mentions temperatures in the seventies (Fahrenheit), and that's only at the warmest times of the year, and only for brief periods in the early afternoon, too! Otherwise, as you realise, the temperatures are well below zero almost all the time.
Another point is that at high altitudes, say like on the Tharsis plateau which is several kilometres above "sea-level" (called "Datum" on Mars because there's no sea! ), the situation is much worse. I haven't seen actual figures, but I believe the temperature there never even gets close to positive figures.
Josh, as usual, is quite correct about the drop in temperature at about 1 metre above the ground, This is because the sun warms the regolith (soil) which, in turn, warms the air directly above it. The same thing happens on Earth and creates the atmospheric layer known as the troposphere, which is relatively warm and moist and is where all the weather "happens"! On Earth, the troposphere extends up to an altitude of about 10-12 kilometres where the air becomes bone dry and bitterly cold. This is the start of what's called the stratosphere.
Due to its thin air and lower insolation (sunlight intensity), it has been suggested that we can envisage the Martian sratosphere as starting at an altitude of 1 metre!! (Instead of the 10 or 12 THOUSAND metres we experience here at home.)
It makes you realise what a job of terraforming we have ahead of us, doesn't it?!
???

Palomar · 2002-06-05 09:00:25

Shaun wrote:

"Hi Cindy!...Due to its thin air and lower insolation (sunlight intensity), it has been suggested that we can envisage the Martian stratosphere as starting at an altitude of 1 metre!! (Instead of the 10 or 12 THOUSAND metres we experience here at home.) It makes you realise what a job of terraforming we have ahead of us, doesn't it?!"

Hi Shaun:

Good grief!! Well, you certainly put it in perspective for me. Yes, I'm beginning to get a better idea of how tough terraforming will be. Wow. Thanks for clarifying.

--Cindy

Shaun Barrett · 2002-06-05 20:22:51

I hope I haven't made things sound too depressing, Cindy!
I'm still hopeful that the whole Martian environment is on a "hair-trigger" as far as the atmosphere is concerned. This is no new idea, of course, but has been made more likely (at least to my mind) by the fabulous good news about the quantity of subsurface water now believed to exist in the Martian regolith. Some people are inclined to think there may be enough (so far discovered) to create a layer up to 500 metres deep over the whole planet .... that's assuming the topography could be smoothed out to make Mars a true sphere!
It may be that just by raising the temperature sufficiently, a whole train of events might be triggered whereby the atmosphere could thicken to maybe 500 mbars or more. If so, you'd end up with a very respectable troposphere virtually automatically! It wouldn't be breathable, of course, since most of it would still be CO2, but we could keep it warm with carefully chosen super greenhouse gases and wander around the surface with a simple "breather" ... no space-suit required!
There!! Doesn't that sound more optimistic?!

Palomar · 2002-06-07 12:33:04

Shaun wrote: "It may be that just by raising the temperature sufficiently, a whole train of events might be triggered whereby the atmosphere could thicken to maybe 500 mbars or more. If so, you'd end up with a very respectable troposphere virtually automatically! It wouldn't be breathable, of course, since most of it would still be CO2, but we could keep it warm with carefully chosen super greenhouse gases and wander around the surface with a simple "breather" ... no space-suit required!

There!! Doesn't that sound more optimistic?"

Hi Shaun: Actually, what you wrote previously didn't depress me...but it did shock me. I do believe and trust that, with brains and willpower, humankind can accomplish colonization on Mars. But it looks like a much steeper road ahead than I'd anticipated.

On a slightly different note, thanks to sci-fi authors, I still can't get the image of Mars being a HOT desert planet out of my head.

I have a huge poster, a composite of 2 photographs of Mars taken by one of the probes, hanging in my office. It's such a gorgeous planet. I keep thinking about people being there some day, and the twinkle of lights from colonies.

We'll get there. We'll do it!

--Cindy

RobS · 2002-06-17 02:33:15

The surface temperature estimates of 60s and 70s are misleading. If you go to a beach on a sunny day, you quickly discover you do not want to walk around barefoot unless the sand is wet, because in direct sunlight it gets up to 130 or 140 degrees and it hurts! But the air never gets that warm (thank God). Same on Mars. The surface may warm up to 60F but the air temperature is permanently like Chicago in January; quite a bit below freezing.

But insulation changes the situation drastically. An airtight bubble of plastic will maintain higher temperatures easily. Even a sheet of plastic laying on top of the ground on Earth--not air tight--raises the surface temperature about ten degrees F. I threw a sheet of plastic over my bathtub-sized fish pond in my back yard in northern Indiana last winter. The pond never froze, even though the air temperature hit zero, and one geranium survived the winter under the plastic. I suspect four or five layers of transparent plastic will maintain room temperature during the day, and if you cover the greenhouse at night it'd do okay all night, too.

-- RobS

Palomar · 2002-06-17 12:35:00

The surface temperature estimates of 60s and 70s are misleading. If you go to a beach on a sunny day, you quickly discover you do not want to walk around barefoot unless the sand is wet, because in direct sunlight it gets up to 130 or 140 degrees and it hurts! But the air never gets that warm (thank God). Same on Mars. The surface may warm up to 60F but the air temperature is permanently like Chicago in January; quite a bit below freezing.
-- RobS

*Thanks for pointing out these important factors. Your post has given me more insight into conditions on Mars.

--Cindy

C M Edwards · 2002-06-20 11:49:00

But insulation changes the situation drastically. An airtight bubble of plastic will maintain higher temperatures easily. Even a sheet of plastic laying on top of the ground on Earth--not air tight--raises the surface temperature about ten degrees F.

True. Because the the thin -- near vacuum -- martian atmosphere can't conduct a lot of heat, air-tight boundaries get a free boost to their effective thermal resistance. Saran Wrap would have an R-value of 3 or 4 on Mars. I don't suspect insulation will be much of a problem.

It would, in fact, be harder to operate an air-tight hotbox at Devon Island here on Earth than it would be on Mars. The incident sunlight at Devon Island is actually less intense than at the surface of Mars because of atmospheric attenuation that far north. And the Earth's atmosphere is a much better conductor of heat than on Mars, so Saran Wrap wouldn't do you much good.

CME

Palomar · 2002-07-01 16:27:29

*I'm wondering how much of Mars [percentage-wise] is consistently as cold, or colder than, Antarctica during its winter months?

--Cindy

Shaun Barrett · 2002-07-01 18:31:03

Hi Cindy!
In reply to your question, I think Antarctica in its winter months is routinely -50 deg.C or lower. I seem to remember that the lowest temperature recorded somewhere on Earth was about -90 deg.C .... this may have been recorded in Antarctica, but I can't swear to it.
I believe that very little of Mars is consistently this cold or colder. Most of its surface manages to warm up to respectable temperatures at least during part of the Martian year. Though, as RobS points out, surface temperatures and air temperatures are not the same thing!
I've seen some very interesting "time-lapse" thermal maps of the Martian southern hemisphere as the spring turns into summer. I was amazed to see that surface temperatures climbed above zero over most of the hemisphere .... down to about 75 degrees south!!
Of course, the northern summer isn't as warm as the southern summer because Mars is currently further from the sun during northern summer. But the northern summer is longer than the southern summer for the same reason. Therefore, I suspect that up to at least 45 or 50 degrees north, ground temperatures should be capable of reaching positive territory during summer. Maybe in sheltered areas during high summer, ice in the regolith may become liquid for short periods even as high as 60 or 65 degrees north. But that is really just speculation on my part.
I hope this has been helpful.

Palomar · 2002-07-02 09:55:20

Of course, the northern summer isn't as warm as the southern summer because Mars is currently further from the sun during northern summer. But the northern summer is longer than the southern summer for the same reason...I hope this has been helpful.

*Shaun, your reply was helpful -- thanks!

--Cindy

SpaceNut · 2016-03-26 18:20:50

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We breifly talked about how the cold affects materials in a few recent topics...

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#1 2002-06-01 15:53:50

Re: "It's a bit chilly today" - Temperatures on Mars

#2 2002-06-01 21:51:53

Re: "It's a bit chilly today" - Temperatures on Mars

#3 2002-06-02 20:53:49

Re: "It's a bit chilly today" - Temperatures on Mars

#4 2002-06-04 16:04:51

Re: "It's a bit chilly today" - Temperatures on Mars

#5 2002-06-04 21:05:20

Re: "It's a bit chilly today" - Temperatures on Mars

#6 2002-06-05 09:00:25

Re: "It's a bit chilly today" - Temperatures on Mars

#7 2002-06-05 20:22:51

Re: "It's a bit chilly today" - Temperatures on Mars

#8 2002-06-07 12:33:04

Re: "It's a bit chilly today" - Temperatures on Mars

#9 2002-06-17 02:33:15

Re: "It's a bit chilly today" - Temperatures on Mars

#10 2002-06-17 12:35:00

Re: "It's a bit chilly today" - Temperatures on Mars

#11 2002-06-20 11:49:00

Re: "It's a bit chilly today" - Temperatures on Mars

#12 2002-07-01 16:27:29

Re: "It's a bit chilly today" - Temperatures on Mars

#13 2002-07-01 18:31:03

Re: "It's a bit chilly today" - Temperatures on Mars

#14 2002-07-02 09:55:20

Re: "It's a bit chilly today" - Temperatures on Mars

#15 2016-03-26 18:20:50

Re: "It's a bit chilly today" - Temperatures on Mars

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