Re: Orientation of ISS relative to Earth?

From: Sebastian Stabroth (
Date: Tue Sep 04 2001 - 19:06:42 EDT

> One other question: what's the orientation of the space station relative to
> the earth? Is the same side always facing down (similar to the moon's orbit
> around the earth)? Or can we see it from different sides as it passes over
> (not counting low passes, just comparing "same" passes through the zenith)?

Right now, the ISS has only one solar array gimbal for effective solar
pointing. To get the most out of this situation (up until 2003 or so),
the station has two possible flight attitudes (as a function of the
solar angle and the right ascension of ascending node of the orbital

- LVLH with the Destiny module in flight direction and the bottom side
always facing nadir - should be active if the orbital plane is aligned
with the Earth-Sun line.

- XPOP (x-axis perpendicular to orbit plane), which is a
'quasi-inertial' reference frame and allows the single solar array
rotary joint along the y-axis to track the Sun. This orientation is
most effective if the orbit is perpendicular to the Earth-Sun line.

So, with LVLH it is only possible to see the bottom side of the
station at zenith. With XPOP you could see any other side at zenith
but based on your latitude, since this attitude mode is fixed to the
stars for the moment and slowly regresses with the orbital plane.

Have a look into the ISS Familiarization Manual (6mb PDF) at


Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
in the SUBJECT to

This archive was generated by hypermail 2b29 : Thu Sep 20 2001 - 17:55:52 EDT