The FUSE Mission Planning Schedule (MPS) timeline plots are generated for use by the Science and Operations team at JHU, but they can also be used by observers to place their observations on a timeline and in the context of orbital events and surrounding observations.

The plots are PDF files, usually with a day per page, and Day/Universal Time as the X-axis. Initially MPSs were approximately a day in length, but varied by at least a factor of two, depending on the events being planned. Later MPSs were usually multi-day schedules (up to 2 weeks in length) unless a re-delivery or re-plan had taken place. A variety of parameters are shown in sub-panels along the Y-axis of these plots. The parameters plotted on these plots have changed during the course of the mission, reflecting changing operational constraints and the evolution of MP tools. The following is a complete list of all possible parameters (and explanations) which appear in various MPS timeline plots. Following this list is a section detailing the time ranges for different combinations of plotted parameters.

Each timeline has two names, although usually only the first is used: an MPS number (e.g. MPS 190), which is a running sequence number starting with the first MPS; and a full name (e.g. mps_2000_165_05122.001), which gives the year, day of year, and orbit number since launch for the start of the MPS, as well as a version number. MPS plots prior to MPS 190 do not have these names printed, although this convention was in use. Replans and redeliveries are handled various ways. If the MPS is a full redelivery of a previous one, usually only the version number on the full name is incremented. If the MPS is a recovery from earlier problems, and has a different starting date, then the short MPS name is usually incremented with a "dot-version" number, and the full name has the new starting values with a version of .001. MPS 185/mps_2000_154_04955.003 and MPS 528.5/mps_2005_220_32288.001 are examples of these cases.

Here is a one day example of an MPS timeline plot.

Each panel contains rows that specify some combination of the following:

• RAM: The instantaneous angle of the telescope boresight to the direction of spacecraft motion.

• OBS: A bar showing the active observation, labeled with ProgramID:targetID:observationID, coordinates in degrees (in later MPSs), target name, and countrate. (On the last few MPSs, the skew wheel bias LN [Low Negative] is also shown.)

• LIMB: The angle of the boresight from the Earth limb (lower dashed line indicates 10 degree limb angle; upper dashed line indicates 30 degree limb angle).

• MOM: Skew wheel Momentum stripchart. The nominal operating range in effect for the particular MPS is shown by the dashed horizontal lines. Discrete numerical momentum values are plotted and referenced by the "open circles" on the stripchart line.

• SAA: Bars on this line show the calculated periods where the spacecraft is passing through the SAA (South Atlantic Anomaly). FUV (Far UltraViolet) observations cease during these periods. An indicator of the SAA model in use is sometimes also shown.

• OCC: Bars on this line indicate periods when the active target is occulted (behind the Earth or below the Earth limb threshold used for planning). If nothing is present on this line, the target was in the CVZ (Continuous Viewing Zone). Note that as a result of operations changes starting with MPS 528, OCC events are plotted for SAAs, even if the target is in the CVZ.

• TMX, NGT: This stands for "Terminator Crossing." Bars indicate when the target is being viewed during orbital night. Blank regions are orbital day.

• SLEW, SLW: Spacecraft slews, either from one target to the next, or small adjustments near a target. The ending beta and pole angles and hemispheres are listed for target-to-target slews. The beta angle is the angular distance between the target and the anti-Sun position (e.g. the Sun is at a beta of 180 degrees). The pole angle is the angular distance between the target and FUSE's orbital pole.

• ACQ: Timing of target acqs (acquisitions), the type of acq performed, and the aperture used. Available apertures are Low Resolution (LWRS, LW, or L); Medium Resolution (MDRS, MD, or M); High Resolution (HIRS, HI, or H); and the Reference Point (RFPT, RP, or R). The acq types used are:
  • 0 - No acq performed
  • 1 - FUV peak-up - the target is scanned across the apertures to center them on the target
  • 2 - Case 3, followed by case 1
  • 3 - FES-assisted acq; FES monitors the target as it is moved to the aperture, followed by tracking on guide stars
  • 4 - Guide star acq; guide stars are locked to their predicted positions with the target in the aperture
  • 11 - Acq on unknown stars
  • 12 - Guide star re-acq - similar to case 4
  • 13 - FES-assisted acq, followed by peak-up in one aperture and observations in another
  • 14 - Peak-up in one aperture and observations in another
  • 15 - Acq at an offset field, followed by small slew to target field, then guiding as in case 4
  • 16 - Re-acq at an offset field - similar to case 15
  • 17 - Fast re-acq
  • 18 - FES target correction only
  
  
• TRQ: Torque authority intervals. A solid black line indicates that the target should remain in the aperture (e.g. no or very few losses of torque authority). A yellow interval denotes possible pointing errors of less than 5 degrees. Larger pointing errors are marked by red intervals (up to 10 degrees) and red crossed intervals (more than 10 degrees).

• S/A: Starting with MPS 282.5 in mid 2001, the SLEW and ACQ lines are combined into a single line. The initial slews are labeled as above with the target beta & pole angles and hemispheres at the start of each observation; acqs and re-acqs are between short vertical lines and are also labeled as above; and small slews in the vicinity of a target are unlabeled dashes. Note that in the cases of offset acqs and re-acqs (15 and 16), the acq/re-acq is performed at the offset field, and is immediately followed by a small slew to the target.
  
  Beginning with MPS 345, the offset from nominal roll is listed along with the slew beta and pole angles, and the slew bar is broken into two parts - the first (white) section shows the estimated slew duration, and the second (black) part shows the settle time following the slew. Later MPSs show the slew rate and type (FAST/H0 [H-zero] or SLOW/L0), along with any allowed delay in the slew start (both by number of seconds, and as a leading black bar in the slew).

• HV: Bars on this line indicate when high voltage is on for at least one detector. This is required for any science exposures and FUV peak-ups, but not for FES-only operations.

• EXP: Science exposures, along with some exposure-related operations:
  
  • A/C - Channel alignment on a FUV-bright target, without science data collection (results stored as engineering telemetry instead)
  • A/T - Similar to A/C, but with the data collected as for time-tag exposures
  • F - FES exposure, with the exposure number above the block
  • G - Generic null activity; used for breaks or place-holders for other activities
  • H - Histogram science exposure, with the exposure number above the block
  • P - FUV peak-up
  • S - Focal-plan split (FP-split) step; the number above the block is the sequence number in the step (the zeroth step being included in the initial acq)
  • T - Time-tag science exposure, with the exposure number above the block
  Note that, especially early in the mission, G blocks were used as placeholders for activities that were later automated with other sequences. MPS 212 shows several examples: alignment activities in M112:32:01, offset acqs and re-acqs in P104:13:01, and FUV peak-ups in P104:12:01.

• GSP: Ground-Station Passes, labled with the ground station involved:
  
  • DSS - NASA's Deep Space Network
  • HAWAII, USN_HAW - US Spacenet at Hawaii
  • TDRSS - Tracking and Data Relay Satellite System; usable for commanding and monitoring, but not for downlinking science data
  • UPRM, UPRM_LEOT - University of Puerto Rico at Mayaguez, FUSE's primary ground station
  • WALLOPS, WFF - NASA's Wallops Island Flight Facility
  
  
• DV: Data Volume stripchart, showing how much memory is being used on the science data recorders. The nominal limit of 100Mb is indicated by the horizontal dashed line. Data volume increases during Histogram, Time-tag, and Alignment-as-Time-tag (A/T) exposures, and decreases during UPRM, Wallops, and Hawaii passes.

• Light Green: Visibility intervals (unocculted, SAA free times) during which FUV exposures can occur.

• Dark Green: Acquisition intervals indicate times when acqs and re-acqs are allowed.

• Pink (on MOM, starting with MPS 578): Periods when the "skew wheel axis to magnetic field" angle is suitable for skew wheel momentum unloading. A "filled circle" to the upper left of the pink region and an "unfilled circle" to the lower right of the pink region indicate times when wheel unloading is switched "ON" and "OFF", respectively.

• Red dashed line: Indicates orbital noon, when Earth is directly behind FUSE as seen from the Sun. Scattered light problems in the FES prevent acquiring targets within a few minutes time of orbit noon, although guiding can be maintained throughout it.

• Blue line: Boundary between discrete observations.

WebMaster: Bill Blair
Last Update: 2 October 2008