POLAR PI TELECONFERENCE: FRIDAY, Sep 26 at 4 p.m. Eastern
POLAR PI TELECONFERENCE: FRIDAY, Sep 26 at 3 p.m. Central
POLAR PI TELECONFERENCE: FRIDAY, Sep 26 at 2 p.m. Mountain
POLAR PI TELECONFERENCE: FRIDAY, Sep 26 at 1 p.m. Pacific
5 min: Misc. updates and announcements
- Press Release: Solar Wind Makes Waves, Killer Electrons go Surfing
- MFE processing status
- "Best of Polar DVD"
5 min: November 12-14, 2003: Polar Science
Workshop at the University of Iowa
Please register your interest and the titles of your talks by October 31, 2003 at the web site.
Hotel reservations should be made now at:
15 min: Operations Update
Science Mode 2 Status:
Waiting on MFE flight software patch
Need updated versions of CEP, CAM, and EFI KP generation software
Final consolidation of data processing functions, LZ processing:
The re-engineered Level Zero processing software is now running in parallel with the legacy system.
The new files are in directories named 'l0' and 'q0' at the same level as the 'lz' and 'ql' directories in the public ftp area. The path to the 'l0' files from the ftp directory is 'ftp://pwgdata.gsfc.nasa.gov/pub/uncompressed/po/(instrument)/l0/2003'.
All instrument teams need to verify the quality of these versions of the 24-hour Level Zero data. Issues that need clarification or correction can be directed to Bobby Candey (firstname.lastname@example.org).
Assuming this verification period goes well, our nominal plan is to permanently cross over to the new system when we start routine Science Mode 2 operations. The directory names 'lz' and 'ql' will be used and the file names will include the 'lz' designation.
Sun angle constraint:
The maneuver we just conducted used an estimated 2.253 kg with the trims an extra 0.048 kg. The estimated total fuel remaining is 3.349 kg. The estimate of unusable fuel out of the total fuel remaining is 1.5 kg. Current mission maneuver planning is based on the 1.8 kg of usable fuel.
A chart is available showing the expected spacecraft attitude progression along with curves showing the range of attitude solutions to be expected subsequent to the next required maneuver.
There are several constraints on the sun-angle we are balancing in order to define the operations plan from that first required maneuver and onward.
Spacecraft thermal constraints require sun-angles above 87 degrees.
The UVI team is concerned about extended (days) exposures to sun angles below 90 degrees. The concern is the UVI electronics stack (ES), not the camera. The ES has a long time constant, so brief exposures (several hours) like during the flip maneuvers are fine. Based on the UVI trend data, the UVI ES will be in a yellow condition (+45C) for sun angles less than 89.3 degrees and be in a red condition (+50C) for sun angles less than 88.6 degrees. There is a plot of UVI Electronic Stack temperatures vs. sun angle. The black data points are for steady state temps, the blue are for transient temps near flip maneuvers. Under steady state conditions the ES will go yellow ~89.2 degress and go red ~88.5 degrees.
Therefore the following UVI requirement is established:
UVI should not be exposed to a sun angle of 89.5 degrees or less for longer than 7 consecutive days, and not be exposed to a sun angle of 89.0 degrees or less for longer than 3 consecutive days. In addition, the time averaged sun angle for any two week period should be equal or greater to 90 degrees.
Related EFI Issue:
Immediately after the most recent maneuver (90.2 deg sun angle), EFI experienced periodic eclipsing of its sensors:
FOR SPHERES 1 AND 2 (each 65 meters from the spacecraft)
Glitches beginning to decrease: 1100 on 09/13/03 (91.04 deg sun angle)
Glitches gone: 2200 on 09/14/03 (91.18 deg sun angle)
FOR SPHERES 3 AND 4 (each 50 meters from the spacecraft)
Glitches beginning to decrease (3): 0200 on 09/17/03 (91.38 deg sun angle)
Glitches beginning to decrease (4): 0600 on 09/17/03 (91.40 deg sun angle)
Glitches gone: 2130 on 09/17/03 (91.45 deg sun angle)
The time range where POLAR is within +/- 1 hour of local noon (GSE) at apogee is 2004 39 to 2004 70.
VIS Constraints: Recall previous VIS input from Sigwarth: I calculate that for an 87 degree sun angle, the VIS will absorb an additional 3.6 Watts of heat from the sun shining on the OSR covered radiators on the top of the box. I dusted off our old programs for predicting the temperatures of the VIS and verified them against some flight data. Then I added the additional heat load to the radiators. The results indicated that the VIS optical bench would rise 4 C in temperature. For a worst case orbit the VIS optical bench temperature would be + 4 C and just barely within the normal operating range. The February through May 2004 timeframe does not represent the worst case orbit configuration and I expect the VIS temperatures to be about 10 degrees cooler than this worst case predict. The planned minimum sun angle of 88.64 degrees decreases the addional heat load by ~ 1/2 and so the situation should be even better. The bottom line is that the VIS should have no problem with the proposed 88.64 degree sun angle minimum and could even be operated as low as 87 degrees.
Bottom line: We are further quantifying the scenarios that optimize fuel usage and the impacts on this fuel usage that any instrument contraints impose. We will discuss the range of options at the November 14 Polar Operations Meeting in anticipation of the Polar Project setting an operations plan for FY04 and FY05 by the end of November.
Science update from MDI
Science update from TIDE
- November 12-14 at Iowa - everyone will be talking about their science!
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