POLAR Telecon Agenda for
Agenda:
0. Upcoming Polar Telecon
1. Operations
2. Senior Review Status
3. MFE Data Processing Status
4. Science Nuggets
5. UVI Science Report
0. Upcoming Polar Telecon
PIs and their designated representatives will be telephoned at their
usual numbers.
Other participants may call in at:
1-800-857-6258, password POLAR TELECON
(Leader: John Sigwarth)
The web site for the final agenda will be:
http://pwg.gsfc.nasa.gov/polar/telecons/2006Jan27/
Future Polar Telecons
Future Telecon Science Discussion Schedule
[Errors/omissions/preferences to: nicola.fox@jhuapl.edu]
February 2006: MDI
March 2006: CAMMICE
April 2006: PWI
May 2006:
June 2006: EFI
July 2006: TIMAS
August 2006: Hydra
September 2006: MFE
October 2006: CEPPAD
November 2006: TIDE
December 2006, PIXIE
January 2007, SEPS
February 2007: UVI
1. Operations
If you have any concerns about Polar operations, please contact Nicky
Fox (nicola.fox@jhuapl.edu)
Sun Angle Maneuver
The next sun angle maneuver is scheduled for Tuesday February 7
The timeline for pre and post-maneuver instrument activities can be
found at
http://pwg.gsfc.nasa.gov/polar/telecons/2006Jan27/Feb_06_Att_adjust.doc
Status of Fuel Usage
for the Maneuvers
The Polar attitude must be maintained periodically by maneuvers to keep the sun from shining for extended periods on the top of the spacecraft. The battery radiators are located on the top of the spacecraft and these are designed to operate away from the sunlight. Solar insolation on this end of the spacecraft will cause the batteries to overheat and would be expected to lead to the eventual demise of the power system.
The Polar spacecraft uses its hydrazine fuel to perform the
maneuvers. At launch, the spacecraft was
loaded with 297.58 kg of fuel. Today,
the remaining fuel is estimated to be 1.76 kg or approximately 0.6%. The system was originally specified to
operate down to 1.5 kg of fuel. That is
1.5 kg of fuel is “unusable”. Note that
this is a specification. It is not
really known at what level the fuel system will begin failing to perform. It is possible that some of this fuel is
available to continue maintaining the Polar attitude and increase the length of
the Polar mission beyond the
|
Maneuver |
Fuel Usage, kg |
Fuel Remaining, kg |
|
|
0.436 |
1.760 |
|
|
0.200 |
1.560 |
|
|
0.312 |
1.248 |
|
|
0.125 |
1.123 |
Table1. Polar fuel usage and remaining fuel. The values in red (the last 2 maneuvers) indicate where the remaining fuel level falls below the 1.5 kg specification on maximum unusable fuel.
Figure 1 shows the angle between the top of the spacecraft and the sun for the next 2 years. Angles less than 90° indicate when the sun is shining on the top of the Polar spacecraft. The spacecraft is designed to survive at angles as low as 87° (i.e. with a small amount of sunshine less than 3° on the top of the spacecraft). For the revised plan, the sun angle will not fall below 87° until November 2007.
Figure 1. Sun-angle drift.
Change of POC for the Polar FOT
Please continue to direct all future FOT related enquiries to Mike
Machado. His telephone number is 301-286-0666 and his email, mmachado@pop500.gsfc.nasa.gov.
If the matter relates to the spacecraft directly, please continue to
contact Steve Hearn at 301-286-0665 (shearn@pop400.gsfc.nasa.gov)
2. Senior Review Status
The results of the senior review are expected to be announced shortly
after the release of the Presidents FY2007 budget on or about February 6. I will be contacting all of the PIs as soon
the results are released.
3. MFE Data Processing Status
4. Science Nuggets
It has been a while since we have produced any science nuggets to send
to NASA headquarters and we have been encouraged to create some. Please come to
the telecon with some ideas for content and send any materials to Nicky (nicola.fox@jhuapl.edu)
5. The UVI Science Report is
available in powerpoint or pdf formats.
Click on the link below for your preferred format.
Powerpoint—http://csds.uah.edu/outflow/telecon/uvi.ppt
PDF— http://csds.uah.edu/outflow/telecon/uvi.pdf