POLAR PI NEWSLETTER - March-April 2004
POLAR TELECON: Thursday April 8, 2004 , , ,
PIs will be telephoned at their usual numbers
Other participants may call in at: 1-800-988-0215, password POLAR TELECON
(Leader: John Sigwarth)
1. Chuck Holmes Meeting report
GTM Upsets and
3. Anomaly Review Team Reports
4. Sun Angle Maneuvers and Plan
5. E/PO Update
6. CAWSES Campaign March 29-April 2, April 19-23
7. Science Discussion: SEPS
The web site for the final agenda will be: http://pwg.gsfc.nasa.gov/polar/telecons/2004Apr08/
Tentative CY04 Science Discussions
[Errors/omissions/preferences to: email@example.com ]
Apr 2004: SEPS
May 2004: UVI
Jun 2004: PWI/MDI
Jul 2004: CAMMICE
Sep 2004: EFI
Oct 2004: TIMAS
Nov 2004: HYDRA
Dec 2004: MFE
Jan 2005: CEPPAD
Feb 2005: TIDE
Funding authorization orders are moving through
the GSFC accounting system for all of those parties that have not received
their full funding for this fiscal year.
The delay was due to the delay in the passing of the
Chuck Holmes is holding mini-reviews with all operating missions. Polar operations through September 2005 and science data analysis until September 2006. Chuck was very interested in the new science topics that Polar is addressing. The science topics highlighted in the meeting included the high time resolution magnetopause crossing measurements for which Forrest Mozer estimates that 30-50 events have been observed in this season. Additional magnetopause crossings are expected next year. Other highlights included observations of ionospheric ions out to the magnetopause, thermospheric composition, and Polar :justify'>In regards to extending Polar ~10 missions will be competing to not be turned off. Chuck was pleased to see that the Polar team is already making preparations for the 2005 senior review with new candidate science topics that were suggested by some of the PI teams. These topics are listed below. If you know of other candidate topics for new science that Polar can address, please send them to John Sigwarth.
New Candidate Science for the Senior Review 2005
Coordinated Studies With the Groundbased Component of THEMIS.
groundbased component of THEMIS will be deployed and
tested in 2005 well before the THEMIS launch.
This comprehensive northern hemisphere network along with POLAR and it e='text-align:justify'>
Radiation Belts During the Declining Phase of the Solar Cycle.
It is known that the radiation belts behave differently during the declining phase of a solar cycle. In early 2005 and continuing through 2007, the Polar orbit will be ideally situated to cross through all zones of the radiation belts again through this declining phase of the solar cycle and continuing down to solar minimum. The long baseline of Polar measurements will be an invaluable resource for radiation belt modelers for the next half decade.
Revisiting the Cusp
Polar in conjunction with Cluster can be used to resolve spatial-temporal ambiguities in the cusp. With Polar in its high bit rate telemetry mode for in-situ measurements details of the cusp not accessible before will now be observed. In addition, Polar can get a second look with high temporal resolution at the high energy particles in the cusp. The origin of these high energy particles has been the subject of considerable controversy.
Two GTM anomalies occurred since the last Polar telecon.
The first was on Wednesday March 3 2004, while out of contact. The FOT was aware of the problem at the start of the scheduled support with station 34 at 2100z - the upset actually occurred at . Telemetry was recovered at . This was the eleventh GTM upset since launch. During the support from 2100-2320z, the MFE ADC was reset, the HYDRA eeprom write-protect flag was cleared, and TIMAS was recovered (DET1 tuning was not performed). There was no commanding to TIDE as it was still configured for the maneuver.
A second GTM anomaly occurred at on April 4 2004. The GTM was restored when the anomaly was first observed during the contact at . MFE and HYDRA were recovered during the same contact. TIDE and TIMAS were restored during the contact at on Sunday, April 5. The MFE flipper will be reset during a subsequent contact to be selected by the MFE team. No other instruments were affected.
There was a Polar/VIS instrument reset on March 27, 2004 between and , which turned off all sensor power. The most probable cause was a brief power undervoltage on the platform, which has happened before in-flight. The instrument was immediately put in a safe non-imaging operating condition. Commanding was performed when the DSN schedule allowed and the instrument was fully operational again by March 31, 2004.
There were two independent anomaly review teams meeting to discuss recent Polar spacecraft issues. Both of these teams have now documented their findings in the form of reports, and the status of Polar has been changed back to /o:p>
An Anomaly Review Team (ART) was formed to investigate the apparent spontaneous switch of the Power Supply Electronics (PSE) Mode Controller (MC) onboard the POLAR spacecraft in September 2003. The anomaly occurred while in a real-time contact following a long duration eclipse. Two parameters were observed to change state from primary to secondary values. The ART studied the history and status of the MC, and concluded that an unknown failure within the power system caused a permanent switch to the secondary MC. This switch over will not impact the operation of the power system or the overall spacecraft operations for the remainder of the mission.
A second ART was formed to investigate the recurring upset of the GGS Telemetry Module (GTM) onboard the POLAR spacecraft. Since launch the primary GTM (GTM-1) upset four times between May 1998 and August 1999. A separate anomaly required the switchover to the redundant GTM (GTM-2) in March 2001. Since the switchover GTM-2 has upset eight times. The reset anomaly is characterized by corrupt data on both the R/T and Playback channels. When this occurs all housekeeping and science data is corrupted for the duration of the anomaly. The ART looked at the possible reasons for the upsets, and determined the science impact if proper recovery procedures were in place. It is not possible to definitely determine a cause of the upsets at this time, but they are believed to be caused by environmental conditions in the mission orbit. At this time the flight operations team (FOT) is able to recover from the upset and return all the instruments to science mode with minimum impact to the science data collected. Currently the upset is an inconvenience to the missions operations but is fully recoverable
An attitude adjustment maneuver was performed on March 1 to prevent the EFI shadow spikes from being an issue through the winter/spring season on the dayside. However, the EFI team noticed that these shadow glitches were appearing in the electric field data at the end of March. It is a deep concern that EFI is experiencing shadowing at this time as the nominal attitude would have kept the sun angle above 91.4 degrees until November and EFI would have been out of the spacecraft shadow for the entire time. The sun angle for March 30 was predicted to be 91.78 degrees. The engineer in the Flight Dynamics Facility reran the sun angle determination for the real time data and found a sun angle of 91.35 degrees, verifying that the EFI spheres are in the spacecraft shadow. Thus, there appears to be a significant error in the predicted attitude for the spacecraft.
Due to a lack of availability of the necessary personnel, the earliest a spacecraft maneuver could be implemented would be around April 21, 2004. This would be outside of the nominal window of +/- 3 hours of local time for the sub-solar magnetopause crossings as per the science operations plan. After consultation with the FOT and EFI teams, it was decided not perform a correction maneuver as it could not be completed within the prime science mode #2 window. Also, a maneuver now would mean less fuel for maneuvers later and an earlier end to the Polar mission and inconvenience to all of the Polar teams as instruments would have to be ramped down and ramped up including some with high voltage. Forrest Mozer agreed that at this time, a large enough number of events had been recorded in order to further the magnetopause study.
The next Polar spacecraft maneuver is planned for November 10, 2004. Scheduling including the necessary Deep Space Network (DSN) time for that maneuver is going on now. We know that the small gradient drift in the attitude of Polar is not well modeled currently and it is hoped that a longer baseline of sun and horizon sensor data acquired in the ecliptic normal attitude will allow for correction for this drift.
The FDF have produced a new version of the maneuver plan which was presented at the last telecon. It was decided to continue with the spacecraft constraints while making a best effort to keep EFI out of the shadows. The plot can be found in the image Baseline sun angle.
Plans for the preciate any help that you are able to give the team. The initial content is complete and many of you have kindly assisted with the review process. The scripts will be generated in the coming week and the on-camera interviews scheduled. You can see some of the new animations at http://superdarn.jhuapl.edu/share/nicky/polar_dvd
SCOSTEP Climate and Weather of the Sun-Earth System in Equatorial Atmosphere) and the ISR World Days in March 29-April 3 2004. The focus of the campaign is the coupling between the high- and low-latitude ionospheres. These campaigns are briefly described at http://www.haystack.edu/schedules/worldays_2004.html
You should make every effort to ensure that your data are processed in a timely manner as we will be setting up a web page in support of this campaign. Please contact Nicky Fox (firstname.lastname@example.org) with relevant information about your data.