POLAR Telecon Agenda for August 25, 2006

Agenda:

0. Upcoming Polar Telecon

1. Operations

2. AGU Special Session

3. Polar SWT Meeting

4. Resident Archives White Paper

5. MFE Data Processing Status

6. VIS Science Report

0. Upcoming Polar Telecon

Friday, August 25, 2006

4 pm ET, 3 pm CT, 2 pm MT, 1 pm PT

PIs and their designated representatives will be telephoned at their usual numbers.

Other participants may call in at:

1-888-606-9536, Password POLAR TELECON

(Leader: John Sigwarth)

The web site for the final agenda will be:

http://pwg.gsfc.nasa.gov/polar/telecons/2006Aug25/

Future Polar Telecons

Next telecon: Friday September 29, 2006

Future Telecon Science Discussion Schedule

[Errors/omissions/preferences to: nicola.fox@jhuapl.edu]

September 2006: EFI

October 2006: TIMAS

November 2006: Hydra

December 2006: MFE

January 2007: CEPPAD

February 2007: TIDE

March 2007: PIXIE

April 2007: SEPS

May 2007: UVI

June 2007: MDI

July 2007: CAMMICE

August 2007: VIS

1. Operations

If you have any concerns about Polar operations, please contact Nicky Fox (nicola.fox@jhuapl.edu)

Eclipse Operations

The Fall eclipse season began August 12 (DOY 224) and will end September 07 (DOY 250). The longest eclipses are about 82 minutes (on 8/22/06 – DOY 234). Looking at Polar's eclipse performance last year, as well as in 1999 when we experienced shadows of comparable duration, it appears that only PWI should be powered off. In the past we have powered off PWI just before each orbit's eclipse entry and powered on right after eclipse end. PWI remains powered for the majority of each orbit during the shadow season to allow EFI access to Search Coil data. PWI commanding is done by the FOT from the Stored Command Table. FOT recommends using this power cycling method again.

In addition, PIXIE, SEPS and CAMMICE/MICS will remain powered off throughout the eclipse season as they are not operational.

Unattended weekends

Following the end of the eclipse period, the FOT will implement ROBOTT release 5.0 (that automates sending the daily Stored Command Table) and transition to unattended weekends, beginning September 9^th, 2006. They will still cover 12 hour shifts during the weekdays. The MOC staff will have a pager to cover emergencies on the weekend.

MOC staff pager: 301-224-0386

Mike Machado should be contacted by cell phone for instrument emergencies.

Mike's cell phone: 443-694-4317

End of Mission Operations

Sadly all good things must come to an end, and our wonderful Polar mission is no exception. It is a fact that our fuel will be exhausted in the very near future and we need to plan for our end of mission. The FOT is currently working on an operations plan for this period and we need to let them know if there are any specific instrument tests/modes/operations that you would like to implement in the last few days of the mission. For example, extreme temperatures.

Please email Nicky (nicola.fox@jhuapl.edu) with your instrument requirements for this (very sad) period.

Hemispherical Antenna Test

On 18 February 2006 (DOY 049), Polar's operating downlink Solid State Power Amplifier, SSPA-2, suffered a loss of output power during a real-time contact. The power output from the SSPA-2 dropped permanently from 17.08 W to 11.06 W as a result of the anomaly. This anomaly is very similar to a failure (AR #487) that occurred on SSPA-1 on December 12, 2002 (02/346/16:05:00z). Similar anomalies also occurred on the Wind spacecraft in 1997 and 2000. As a result of the anomaly, the Polar mission experienced degraded data during some telemetry downlink contacts. These were correlated with low aspect angles when the receiving ground station is well away from the spin plane of the Polar spacecraft.

The Polar Flight Operations Team (FOT) evaluated the operational benefit of using the hemispherical antennas in addition to the belt antennas. These hemispherical antennas are designed for 0-60 and 120-180 degree aspect angles so their use is limited to supports which lie entirely within these ranges – roughly 33-50% of supports. On Tuesday, April 25, 2006, Polar +Z Hemispherical Antenna was tested and the results were very positive - an improvement of 8 dB—more than a factor of 6 improvement in signal strength. Due to the successful results of this test, it was decided to use this operational mode on a permanent basis.

Since the SSPA#1 anomaly, we have used Comm Mode 10 for Belt antenna - RF switch 5 in ‘A’ Position with SSPA-2. It was determined that the mode 9/12 pair provided the best link margin for critical Belt antenna ops. In order to go from Comm Mode 10 to 9, it required throwing RF switch 5 once (to ‘B’ Position). It was decided to pair Comm Mode 12 with Mode 9 to avoid repeated throwing of RF switch 5; Mode 12 uses SSPA-2 with the Hemi antennas.

On May 31, 2006, the Polar team successfully executed commands to switch the communications modes to the various modes that will be used for nominal and non-nominal aspect angle supports. The first switch was made to go from Comm mode 10 (SSPA #2 with belt antenna) to Comm mode 12 (SSPA #2 with +Z Hemi Antenna) at 182847 UTC using the procedure to send the commands. This involved throwing RF switch #5 from the A to the B position. At this point, the degraded data experienced during the support cleared up. At 183952 UTC, the configuration was changed to Comm mode 9 (SSPA #1 with belt antenna) using the macro. Data quality continued to remain good with no dropouts. At 185011 UTC, the configuration was changed back to Comm mode 12 using the macro to verify all the operational products. Since all the operational products were successful, the Stored Command Table (SCT) load was uplinked and enabled at 185640 UTC.

With these new operations configurations, we have achieved significantly higher data quality despite poor aspect angles with overall data capture rising again to 95% for the last month and 88% cumulative for the year.

Polar Attitude Determination Error

Since the last maneuver it has been determined that the attitude solutions for Polar, that is, the location of the spin axis relative to the celestial sphere, contained large errors of ~ 1-2 degrees which are well outside the specification of 0.2 degree. The error in the attitude solution was due to the close alignment of the Sun, Earth, and Polar for the available sun pulse and horizon pulse data during the February and August time frames +/- ~ 1 month. Outside of these times, the attitude determinations appear to be within specification.

The FDF has reprocessed the 12-week periods centered on the February and August high attitude error times in reverse time order.

2/9/2006 – 5/13/2006

12/4/2005 – 2/5/2006

7/3/2005 – 10/2/2005

3/6/2005 – 4/17/2005

1/23/2005 – 2/27/2005

12/05/2004 – 1/16/2005

7/04/2004 – 10/10/2004

3/7/2004 – 4/18/2004

1/11/2004 – 2/29/2004

The new sun angle drift plot, based on the new data can be viewed at http://pwg.gsfc.nasa.gov/polar/telecons/2006Aug25/sun_angle_june_2006.jpg

Sun Angle Maneuver

The next Polar maneuver is tentatively scheduled for October 5, 2006. We expect to use ~ 0.3 kg of fuel with 1.5 kg estimated currently in the tanks. It is not clear how much of the remaining 1.5 kg is usable for maneuvers.

2. AGU Special Session

We would like to hold a special session at the Spring 2007 AGU which will be held in Acapulco, Mexico. The proposed session description is below – comments encouraged.

Advances in understanding of magnetospheric physics during the Polar mission era

The Polar spacecraft mission was initiated to study the flow of energy and particles into and through the magnetosphere. The Polar spacecraft has acquired observations of electric and magnetic fields, low and high energy plasmas and particles, and images of the auroras for nearly a complete solar cycle from solar minimum through solar maximum and back again. These measurements have been combined with observations from the other components of the Heliophysics Great Observatory and ground-based experiments to produce a more complete understanding of the workings of the magnetosphere immersed in the solar wind and tied to the ionosphere. These advances include topics such as the magnetopause, reconnection, radiation belts, geomagnetic storms, substorms, cusp regions, auroras and the ionosphere. As the Polar spacecraft nears the end of its operational life, it is timely to review what has been learned and what open questions remain to be answered by future missions.

In this session we solicit presentations and posters on the advances in our understanding of magnetospheric physics made possible by the Polar mission in conjunction with the Heliophysics great observatory.

3. Polar SWT Meeting

The Polar mission operations are currently scheduled to finish on March 31, 2007 and at this time it is anticipated that the spacecraft will be decommissioned. We would like to hold a science workshop in conjunction with these milestone spacecraft operations. In addition, there will be a small gathering of PIs in the control room when the last command is sent to the spacecraft. We would then have the science meeting on the following 2 days.

4. Resident Archives

The Polar mission delivered a white paper proposing the structure of resident archives for the Polar data. We were encouraged to take as many cost saving measures as possible (i.e.) combining data sets within institutions or across institutions where it makes financial sense and to be working to set these up now so they can be ready for operation in the post-Polar era.