It was important to know the vehicle weight for not only on-orbit state vector propagation, but also in the event of an unplanned or emergency deorbit situation to know if we needed to burn off extra fuel to get down below a certain maximum down-weight level.

The “NAV SV” was the latest Navigation-computed State Vector, based on tracking from both ground-based (C-band and S-band) tracking stations and TDRS (S-band) tracking.  

V39 was the normal Mission Operations Computer (MOC) vector storage slot reserved for the “current/best state vector”.

Note that I had entered the Δa and Δv values.  This was to note the difference between the newly computed State Vector and the last SV (in Ephemeris 1) and the current onboard SV (FLTI) for both semi-major axis and downrange deltas. There were specific Space Shuttle Flight Rules written to define the values within which the FDO would keep the SV inaccuracies. (hint: these were within those values)

To do that, the MOC had to be set into a special processing phase and verified a day in advance. I was just noting that event here, and the reason why we hadn’t yet updated the onboard SV.

The FDOs were the points-of-contact for SPADOC, providing state vectors for evaluation of potential orbital debris conjunctions. In addition to providing post-burn trajectory planning vectors well in advance, we would provide “regular” daily update vectors just to refresh the SPADOC ephemeris for the Shuttle – since we were better at predicting our “big bird” than they were. 🙂

So this was indicating that I had sent the 22Z (Zulu, aka “GMT”) vector to SPADOC.

This is done with a very special command uplink, known as the 40101 upload. The FDO, through the DYNAMICS backroom controller, would create a 40101 command set containing the selected state vector and would then ask INCO (Integrated Communications Officer) to upload to the onboard computers – after receiving permission from FLIGHT, of course. If the crew were awake, CAPCOM would announce the SV update to the crew – for situational awareness, if nothing else.

Since this was my last flight and my last shift, my INCO buddy asked if I wanted to actually “push the button” and send the physical state vector to Atlantis. OF COURSE I jumped at that opportunity… and with that, at Mission Elapsed Time of 8/19:48, I unplugged my headset from the FDO console for the last time.