Astronomy Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.



 
PortalPortal  HomeHome  SearchSearch  Latest imagesLatest images  RegisterRegister  Log in  
Log in
Username:
Password:
Log in automatically: 
:: I forgot my password
Latest topics
» NASA Invites Students to Name Moon-Bound Spacecraft
Mars' Atmosphere  EmptyTue Oct 04, 2011 1:18 pm by AstroJunkie

» NASA Leads Study of Unprecedented Arctic Ozone Loss
Mars' Atmosphere  EmptyTue Oct 04, 2011 1:17 pm by AstroJunkie

» Electrical Circuit Between Saturn and Enceladus
Mars' Atmosphere  EmptyTue Sep 27, 2011 4:00 am by AstroJunkie

» The Big Bang Theory
Mars' Atmosphere  EmptyTue Sep 27, 2011 3:56 am by AstroJunkie

» subatomic particles breaking the universal speed limit
Mars' Atmosphere  EmptyMon Sep 26, 2011 10:04 am by andy 'astrojunkie'

» Tatooine system found
Mars' Atmosphere  EmptyFri Sep 23, 2011 12:36 am by astrolover

» hello
Mars' Atmosphere  EmptySat Sep 17, 2011 2:53 am by AstroJunkie

» Soyuz undocking
Mars' Atmosphere  EmptyFri Sep 16, 2011 11:38 am by AstroJunkie

» NASA’s Kepler Mission Discovers a World Orbiting Two Stars
Mars' Atmosphere  EmptyFri Sep 16, 2011 6:26 am by AstroJunkie

Statistics
We have 126 registered users
The newest registered user is bardokall

Our users have posted a total of 1051 messages in 208 subjects

 

 Mars' Atmosphere

Go down 
4 posters
AuthorMessage
Starmonger




Posts : 5
Join date : 2011-08-23

Mars' Atmosphere  Empty
PostSubject: Mars' Atmosphere    Mars' Atmosphere  EmptyTue Aug 23, 2011 5:15 pm

If Mars didn't have enough gravity to maintain its Atmosphere how did it develop one in the first place? Shouldn't it have evaporated or drifted out into space as it was forming?
Back to top Go down
scopeman

scopeman


Posts : 116
Join date : 2011-08-23

Mars' Atmosphere  Empty
PostSubject: Re: Mars' Atmosphere    Mars' Atmosphere  EmptyTue Aug 23, 2011 5:18 pm

It's not a binary situation where a planet has enough gravity for an atmosphere or can't hold onto any atmosphere. The major factors are escape velocity at the uppermost levels of the atmosphere compared to the velocity distribution of the molecules at those altitudes, and the rate of replacement. A molecule moving faster than escape velocity in the uppermost reaches of the atmosphere has a good chance of escaping the planet. If the rate of loss is greater than the rate of replacement, the atmosphere will thin until the two are equal.

The replacement rate also varies over time. Mars was more volcanically active in the past. Also, the rate of bombardment by asteroids and comets was higher in the past. Both of these mean that the replacement rate of atmosphere used to be higher.
Back to top Go down
TomK

TomK


Posts : 58
Join date : 2011-08-23

Mars' Atmosphere  Empty
PostSubject: Re: Mars' Atmosphere    Mars' Atmosphere  EmptyTue Aug 23, 2011 5:19 pm

And maybe the presence of iron, and massive volcanoes indicate that Mars was capable of having a stronger magnetic field at one time.

I don't think that it has ever been concluded, but some of the pieces are there.
Back to top Go down
AstroJunkie
Admin



Posts : 219
Join date : 2010-07-22
Age : 33

Mars' Atmosphere  Empty
PostSubject: Re: Mars' Atmosphere    Mars' Atmosphere  EmptyTue Aug 23, 2011 5:20 pm

TomK wrote:
And maybe the presence of iron, and massive volcanoes indicate that Mars was capable of having a stronger magnetic field at one time.

I don't think that it has ever been concluded, but some of the pieces are there.

It also isn't concluded if a magnetic field would have been a major factor affecting atmosphere loss. What is certain is that lower mass means Mars would have lost atmosphere more easily than Earth (and Venus as well) with a tenth the mass of Earth it just can't hold onto atmosphere as effectively.
Back to top Go down
http://www.astrojunkie.com
TomK

TomK


Posts : 58
Join date : 2011-08-23

Mars' Atmosphere  Empty
PostSubject: Re: Mars' Atmosphere    Mars' Atmosphere  EmptyTue Aug 23, 2011 5:22 pm

^ this Cool
Back to top Go down
Sponsored content





Mars' Atmosphere  Empty
PostSubject: Re: Mars' Atmosphere    Mars' Atmosphere  Empty

Back to top Go down
 
Mars' Atmosphere
Back to top 
Page 1 of 1
 Similar topics
-
» Why is Mars red?

Permissions in this forum:You cannot reply to topics in this forum
Astronomy Forum :: AstroJunkie :: General Astro Discussion-
Jump to: