1. Antenna Contact During Calibration Maneuvers
Joseph A. Hashmall
Laurie Mann
a.i. solutions, Inc.

2. Agenda Handovers Calibration Maneuvers Constraints
Joseph A. Hashmall 2
Laurie Mann January 2007

3. Handovers Antennas are always on
Antenna beam can not hit the spacecraft
Loss of Signal
Possible Damage to Instruments
Antenna Masks
Masks implemented in onboard software to prevent violation
Masks created and validated by Mechanical Engineering
Handovers do not violate vibration constraints
Joseph A. Hashmall 3
Laurie Mann January 2007

4. Antenna Masks 3-d plot of unit vectors -Z antenna can not point here
-X (into plot)
+Z antenna can not point here
Joseph A. Hashmall 4
Laurie Mann January 2007

5. Antenna Masks in Antenna Coordinate System
Azimuth/Elevation Coordinates
Joseph A. Hashmall 5
Laurie Mann January 2007

6. Handover and Eclipse Seasons
Joseph A. Hashmall 6
Laurie Mann January 2007

7. Gimbal Angles During Handovers
Joseph A. Hashmall 7
Laurie Mann January 2007

8. Gimbal “Path” Without Handover With Handover Joseph A. Hashmall 8
Laurie Mann January 2007

9. Calibration Maneuvers
HMI/AIA Roll (360 deg)
22.5 degree steps (10 minutes)
15 minute dwell times for calibration
About 7 hours duration
Twice a year (near eclipse season)
EVE Cruciform (2.5 deg)
No more than 2.5 degree offset
Offset in pitch and yaw
About 9 hours duration
Four times a year
Other calibration maneuvers are small
Joseph A. Hashmall 9
Laurie Mann January 2007

10. Constraints Maintain Contact Observe gimbal rate constraints
For HMI/AIA Roll during dwell times
Observe gimbal rate constraints
Calibration during daylight (non-eclipse)
Star trackers not both occulted
Joseph A. Hashmall 10
Laurie Mann January 2007

11. Scheduling Strategy EVE Cruciform HMI/AIA Roll
Schedule during non-handover season or
Schedule so that +Z excursion occurs near northern extreme or –Z excursion near southern extreme
HMI/AIA Roll
Schedule to replace a handover during handover season
Joseph A. Hashmall 11
Laurie Mann January 2007

12. EVE Cruciform ScheduleN +Z
White Sands -Z
Plus Pitch here or
Minus Pitch here
Sun +Z -Z
Joseph A. Hashmall 12
Laurie Mann January 2007

13. HMI/AIA Roll Schedule Roll Maneuver Replaces Handover +Z N White Sands
Sun -Z +Z
Roll Maneuver Replaces Handover
Joseph A. Hashmall 13
Laurie Mann January 2007

14. HMI/AIA Roll Schedule Constraints
No antenna interference
Minimize required gimbal rates
Minimize periods with both Star Trackers occulted
All dwell periods in Sunlight (during eclipse season)
Joseph A. Hashmall 14
Laurie Mann January 2007

15. Joseph A. Hashmall 15
Laurie Mann January 2007

16. Joseph A. Hashmall 16
Laurie Mann January 2007

17. HMI/AIA Roll Variables
Maneuver time
Roll direction
IF NEEDED
Dwell time (greater than 15 minutes)
Step time (greater than 10 minutes)
Joseph A. Hashmall 17
Laurie Mann January 2007

18. Joseph A. Hashmall 18
Laurie Mann January 2007

19. Maneuver Planning Parameters
Maximum Gimbal Rates
If below limit then continuous tracking possible
Vibrations damp during settling period
Maximum Mean Gimbal Rates
Mean rate over each maneuver segment
If mean rate less than limit then antenna can target final required gimbal position
Tracking after settling period
Minimize Rates
Joseph A. Hashmall 19
Laurie Mann January 2007

20. Planning Parameter Results (1)
Joseph A. Hashmall 20
Laurie Mann January 2007

21. Planning Parameter Results (2)
Joseph A. Hashmall 21
Laurie Mann January 2007

22. Planning Parameter Results (3)
Joseph A. Hashmall 22
Laurie Mann January 2007

23. Planning Parameter Results (4)
Joseph A. Hashmall 23
Laurie Mann January 2007

24. Summary(1)
No problems scheduling most calibration maneuvers are anticipated
HMI/AIA roll calibration maneuvers will require significant planning
There are periods in any day during which all gimbal angle and rate constraints are met
Joseph A. Hashmall 24
Laurie Mann January 2007

25. Summary(2)
Precise criteria for optimizing maneuver times must be specified
Tracking or Direct Slew?
Minimum vibrations after settling
Beam path over land (if direct slew)
Changes in calibration maneuver profiles (maneuver dwell times or slew rates) are not anticipated
Joseph A. Hashmall 25
Laurie Mann January 2007