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tofu
2009-Jun-22, 01:00 PM
A recent Universe Today story (http://www.universetoday.com/2009/06/17/fuel-leak-delays-shuttle-again/) features the line:
The next opportunity to launch Endeavour will be on July 11 because of because of temperature constraints related to the International Space Station's orbit.

Last week I posted a comment in the thread attached to that story asking what that means, but didn't get a response. So I'll ask here, does anyone know what exactly is a "temperature constraint related to the ISS's orbit?"

ngc3314
2009-Jun-22, 01:31 PM
A recent Universe Today story (http://www.universetoday.com/2009/06/17/fuel-leak-delays-shuttle-again/) features the line:

Last week I posted a comment in the thread attached to that story asking what that means, but didn't get a response. So I'll ask here, does anyone know what exactly is a "temperature constraint related to the ISS's orbit?"

The shuttle uses radiators on the inside of the payload bay doors to help maintain temperature. The design relies on having the radiators being able to face empty and cold space for a certain fraction of the time. At the orbital altitude and high inclination of the ISS orbit, there is a period around each solstice when ISS is in continuous sunlight and a longer period when there is little darkness. When the shuttle is docked, it doesn't have the freedom to orient the radiators for maximum effectiveness, so the continuous-sunlight periods would overwhelm temperature control.

Amber Robot
2009-Jun-22, 03:37 PM
Is there a website that shows the projection of the ISS orbit on a map of the Earth that also shows the light/dark areas? I think it would be obvious what you're saying in that case.

slang
2009-Jun-22, 04:29 PM
Is there a website that shows the projection of the ISS orbit on a map of the Earth that also shows the light/dark areas?

Like this one (http://heavens-above.com/orbit.aspx?satid=25544&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET) (Heavens Above)?

Amber Robot
2009-Jun-22, 05:07 PM
Like this one (http://heavens-above.com/orbit.aspx?satid=25544&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET) (Heavens Above)?

Something like that, but where you can enter the date and time.

To me, it sounds like the issue that NGC3314 described is one in which the ground track of ISS is very close to the ground track of the terminator in that bottom image. In that case, the amount of orbital nighttime could be quite small. Am I right? This would only happen with a high inclination orbit like the ISS has and near the time of the solstices.

ngc3314
2009-Jun-22, 05:55 PM
Something like that, but where you can enter the date and time.

To me, it sounds like the issue that NGC3314 described is one in which the ground track of ISS is very close to the ground track of the terminator in that bottom image. In that case, the amount of orbital nighttime could be quite small. Am I right? This would only happen with a high inclination orbit like the ISS has and near the time of the solstices.

The NASA real-time ISS tracker (http://spaceflight.nasa.gov/realdata/tracking/index.html) shows the terminator and orbit, but I can't find one that will let you enter a specific date and show the ground track either.

tofu
2009-Jun-23, 03:15 PM
Good info. Thanks ngc3314