APOD: The ISS over Earth (2016 Apr 18)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: The ISS over Earth (2016 Apr 18)

Post by APOD Robot » Mon Apr 18, 2016 4:06 am

Image The International Space Station over Earth

Explanation: The International Space Station is the largest object ever constructed by humans in space. The station perimeter extends over roughly the area of a football field, although only a small fraction of this is composed of modules habitable by humans. The station is so large that it could not be launched all at once -- it continues to be built built piecemeal. To function, the ISS needs huge trusses, some over 15 meters long and with masses over 10,000 kilograms, to keep it rigid and to route electricity and liquid coolants. Pictured above, the immense space station was photographed from the now-retired space shuttle Atlantis after a week-long stay in 2010. Across the image top hangs part of a bright blue Earth, in stark contrast to the darkness of interstellar space across the bottom.

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madtom1999
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by madtom1999 » Mon Apr 18, 2016 7:19 am

I notice the solar panels are not all pointing in the same direction. Is this to help control generation to match demand or are the being used like solar sails to guide the craft?

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geckzilla
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by geckzilla » Mon Apr 18, 2016 9:01 am

madtom1999 wrote:I notice the solar panels are not all pointing in the same direction. Is this to help control generation to match demand or are the being used like solar sails to guide the craft?
They actually increase drag depending on which direction they are facing as the ISS travels through the very, very thin atmosphere. They may be in a transitional state from one of the modes they run in to help reduce this drag.
https://en.wikipedia.org/wiki/Night_Glider_mode

Or, who knows, maybe they were being flipped around so that astronauts on the space shuttle could visually inspect them. I don't suppose anyone from mission control might be around to offer any other suggestions or a definitive answer.
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by Chris Peterson » Mon Apr 18, 2016 2:27 pm

madtom1999 wrote:I notice the solar panels are not all pointing in the same direction. Is this to help control generation to match demand or are the being used like solar sails to guide the craft?
There can be many things going on. They feather the panels when spacecraft are nearby to reduce forces on the ISS from thruster exhaust (which is probably the most common reason we see them that way in outside pictures). They change their angles to manage demand. They change them to avoid certain shadows from the ISS structures. The motors don't all run at the same maximum rate, so during changes they can be at different angles.
Last edited by Chris Peterson on Mon Apr 18, 2016 2:33 pm, edited 1 time in total.
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by Asterhole » Mon Apr 18, 2016 2:28 pm

It's quite an impressive structure, and more keeps being added on.
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by Fred the Cat » Mon Apr 18, 2016 2:35 pm

While walking last night shortly after sunset in Idaho looking up to see the Moon and Jupiter conjunction there was a bright light just south of the two heading East. We followed it for a very long period of time; around 5 minutes, and suspected it was a chance run-in with ISS in the sky.

It was only listed as very short appearance last night on "Spot the Station". It wasn't even listed on Heavens Above until I clicked on "All Passes". We are about 5 miles north and west of the listed city - Boise. It really appeared much brighter and for much longer than the listed sighting.

On "Spot the Station" for (Sun Apr 17, 8:54 PM < 1 min 15° 15° above SE 10° above SE) it lists the pass-over as a brief appearance and it wasn't even shown as a visible pass on Heavens Above which we have set to our city's coordinates. It seems like these sites were not "in conjunction" with our visible observation. Any ideas?
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Re: APOD: The ISS over Earth (2016 Apr 18)

Post by Boomer12k » Mon Apr 18, 2016 9:38 pm

What an awesome shot... so beautiful...

I FINALLY hit good weather, and have gotten out the 10" Meade. Check out my post in the other forum...
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Latest pics...from Boomer12k.

Hope that was alright to post that...
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