How Much Thermal Radiation Does Mars Emit?

[stevemclaren]

Homework Statement

the thermal radiation of mars

Homework Equations

i understand Earth radiates at 237W/m^2 into space but i can't find out how much Mars radiates, i know it has an average temp of -55 degrees C so i know its going to be a lot less but i don't know how much. i need this for a spacecraft design project I am doing

The Attempt at a Solution

see above

would really apprieciate any help on this one guys

x

 

[Kurdt]

If you know the mean temperature you can make a pretty good guess using the Stefan-Boltzmann law.

 

[stevemclaren]

sure thing but as Mars is not a blackbody then what value shall i use for the emmissitivty? (e in the equation P=e*sigma * t^4* area)

also would atmospheric makeup have an effect?

cheers

 

[kamerling]

You can also calculate how much energy Mars gets from the sun, mimus what it immediately reflects away (albedo). This avoids the error you make by taking the average temperature.

 

[stevemclaren]

sure that's sounds good,
the albedo of Mars is 0.15 so it will take in 0.85 of the suns energy after initial reflection.
will it then re emit all of this?
also does anyone know the relationship between altitude and thermal emmission, the satellite I am trying to design will fly 278km above mars' surface so I'm trying to calculate the effect of Mars on its temperature

cheers all