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I would like to know the meaning of a sentence below:

"While docked, the ATV will perform ISS attitude control, debris avoidance manoeuvres and raising of the 183 tonne station's orbit to overcome the effects of atmospheric drag."

(From: http://www.space-propulsion.com/spacecraft-propulsion/bipropellant-thrusters/200n-bipropellant-thrusters.html#moved)

I cannot understand "raising of the 183 tonne station's orbit...". The weight of ISS is not 183 tonne, right? What does this "183 tonne" refer to?

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    $\begingroup$ The ISS increased in mass as it was built, but by 2008 when the first ATV mission happened, most of the major elements were in place. The cupola, the JEF, the PLM, and a couple of Russian modules plus a few other small things were added later. I think it's just an error. It weighs about 400 tonnes now. $\endgroup$ – Organic Marble Sep 2 '17 at 1:08
  • $\begingroup$ Oh, it's an error! Now I understand. Thank you, but I have one more question... The ATV had 28 thrusters. Did all of these thrsuters need to operate simultaneously in order to keep orbit? I just want to know how much acceleration is needed to keep 400 tonne station in orbit. It would be helpful if you to give me any information about that. $\endgroup$ – Grass Sep 2 '17 at 1:23
  • $\begingroup$ Please ask another question! And welcome to Stack Exchange. $\endgroup$ – Organic Marble Sep 2 '17 at 1:24
  • $\begingroup$ In relation to that followup question, see space.stackexchange.com/questions/10890/… $\endgroup$ – Russell Borogove Sep 2 '17 at 1:25
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    $\begingroup$ The 28x 220N thrusters on ATV are small ones used for attitude control and docking; the reboost is performed with the main engines, 4x 490N R-4Ds. See en.wikipedia.org/wiki/Automated_Transfer_Vehicle for more information. The number and thrust used isn't that important; if you have less thrust you just spend more time on reboost. $\endgroup$ – Russell Borogove Sep 2 '17 at 1:29
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According to WP, by summing up the masses of the modules in the order they were added to the station, the mass of the ISS was quite close to 183 tons after the installation of the P3/P4 truss and solar arrays by STS-115 in September 2006.

ATV was in development at that time, but didn't go into service until 2008. Most likely the information on your page is dated from 2006.

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  • $\begingroup$ Yes,you are right. I think I should check the latest information, not the information in 2006. Thank you! $\endgroup$ – Grass Sep 2 '17 at 1:28

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