Quote from: jscman on 09/15/2009 03:55 amRemember that what you are seeing is the ground track of the two vehicles and not the orbit plane strictly speaking. At the time of this snapshot, the ISS and HTV are several thousands of kilometers apart from each other along the same orbit. Let's play a thinking game:Say that the ISS is at its most northern part of its ground track and the HTV was at the most southern part of its ground track. And let's say that they are in exactly the same plane and the same orbital height. Fast forward one-half revolution. Now the HTV is at its most northern portion of its orbit. Is it over the same spot as ISS was one-half orbit ago? NO. Why? Remember that the Earth rotated on its own axis over that half orbit so when HTV comes flying by it won't be over the same spot even though it is in the same orbit. This is what you are seeing.They might really be in different planes at this point, too. Capture and berthing is several days away and there's a lot of differential nodal regression between now and then...
Remember that what you are seeing is the ground track of the two vehicles and not the orbit plane strictly speaking. At the time of this snapshot, the ISS and HTV are several thousands of kilometers apart from each other along the same orbit. Let's play a thinking game:Say that the ISS is at its most northern part of its ground track and the HTV was at the most southern part of its ground track. And let's say that they are in exactly the same plane and the same orbital height. Fast forward one-half revolution. Now the HTV is at its most northern portion of its orbit. Is it over the same spot as ISS was one-half orbit ago? NO. Why? Remember that the Earth rotated on its own axis over that half orbit so when HTV comes flying by it won't be over the same spot even though it is in the same orbit. This is what you are seeing.
Then why is that Progress/Soyuz do not show their own separate orbit/groundtrack lines on the worldmap? I don't remember ATV showing different lines either...
There is a LIVE thread for this now.