From my earlier post, I incorrectly stated: >I believe the X-axis stays perpendicular to the ground. Soyuz leading. Actually, the X-axis is =parallel= to the ground with the Soyuz =trailing=. (I should have known better than replying before the first cup of coffee in the morning. Sorry for the confusion...) Transcribed from the Expedition One Mission Status Briefing (via NASA TV on 2000.12.15) Reporter: Phil Chein - "Earth News" Official: Jeff Hanley - Expedition One Lead Flight Director Q. The P6 Array - Is it rotating now to face the Sun throughout the orbit or are you just leaving it in one position and just accepting the fact that you are not getting all the watts - which you don't really need anyway? A. We're leaving it in one position - wings flat and level - and we won't start rotating them until the beta angle, relative to the orbit plane - the angle of the Sun relative to the orbit plane - gets high enough for us to see a drop off in the performance of the wings. But we're very satisfied with the performance of the solar arrays to date. Q. So are you in an "X-POP" attitude still or are you in "LVLH" to minimize the drag because of the big arrays? A. We're in "LVLH". We plan to stay there throughout the beta regime. As the beta grows and then decreases we plan to stay in LVLH to save propellant. The propellant costs in flying "X-POP" is very high. We'd really like to avoid that till we get the CMG system on the US segment active and can use momentum management to hold attitude. (later in the briefing - from Phil) Q. One more question about the attitude with the "LVLH". I assume it's PMA forward - Z1 going to nadir - PMA-3 going to zenith, straight into the flight direction? A. No. PMA-3 is facing Earth. P6 is sticking up, facing the zenith and wings flat. It's in the attitude you saw in the fly-around video when the (STS)97 crew undocked from the station. It's in exactly the same attitude. Here is a good picture of the arrangement. POV is behind the station's line of travel. http://spaceflightnow.com/ops/stage4a/001209snapshots/withearth.html Here is a tech paper on ISS attitudes. (with illustrations) http://idb.exst.nasda.go.jp/edata/02110/199810K02110020/199810K02110020.html Figure 1.1.1-1 is a good example of "LVLH". "LVLH" = Local Vertical, Local Horizontal Jeff ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
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