Wednesday, May 10, 2000 (DOY 124/19:00:00 to DOY 131/19:00:00 UTC)

Launch / Days since Launch = Nov 7, 1996 / 1281 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 405 days
Total Mapping Orbits = 5250
Total Orbits = 6853

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm036 sequence executed successfully from 00-125 (5/4/00) through 00-128 (5/7/00). The mm037 sequence also successfully executed from 00-129 (5/8/00) through 00-131 (5/10/00). The mm038 sequence was successfully uplinked on 00-130 (5/9/00) and will begin execution on 00-132 (5/11/00).

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 16 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm037 and mm038 sequences. Total command files radiated to the spacecraft since launch is 4638.

Upcoming Events:

A bistatic radar experiment, in which the Spacecraft signal will be reflected off the Martian surface to Earth, is in final development and will execute on May 14. The commands to perform this experiment have been incorporated into the mm039 sequence, which is scheduled to be uplinked on 00-134 (5/13/00)

The next monthly MOLA off-nadir polar scan mini-sequence (mz051) is also in final development and will execute over 12 consecutive orbits beginning on May 17.

The implementation of the first Radio Science occultation egress scans, replacing the previous fixed-HGA periods for obtaining occultation egress data, is also in development at this time and is scheduled for execution on 5/20-5/22/00.

Launch / Days since Launch = Nov 7, 1996 / 1274 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 398 days
Total Mapping Orbits = 5164
Total Orbits = 6767

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm034 sequence executed successfully from 00-118 (4/27/00) through 00-121 (4/30/00). The mm035 sequence also successfully executed from 00-122 (5/1/00) through 00-124 (5/3/00). The mm036 sequence was successfully uplinked on 00-123 (5/2/00) and will begin execution on 00-125 (5/4/00).

The mz050 mini-sequence, containing the retry of the two missed MOC focus star scans, successfully executed on 4/28 and 4/30. The updated quaternion for these scans correctly accounted for the bias error due to the IMU being commanded to high rate mode and resulted in the stars being correctly centered in the image.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 11 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm035 and mm036 sequences. Total command files radiated to the spacecraft since launch is 4622.

Upcoming Events:

A bistatic radar experiment, in which the Spacecraft signal will be reflected off the Martian surface to Earth, is in final development and will execute on May 14.

The next monthly MOLA Off-Nadir Polar Scans is about to begin development. The scans are scheduled for 12 consecutive orbits beginning on May 17.

The implementation of the first Radio Science occultation egress scans, replacing the previous fixed-HGA periods for obtaining occultation egress data, is also on schedule for execution on 5/20-5/22/00.

Launch / Days since Launch = Nov 7, 1996 / 1267 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 391 days
Total Mapping Orbits = 5078
Total Orbits = 6681

Recent Events:

MGS reached the 5000 mapping orbit milestone on 00-111 (4/20/00) at 12:31:55 UTC.

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm032 sequence executed successfully from 00-111 (4/20/00) through 00-114 (4/23/00). The mm033 sequence also successfully executed from 00-115 (4/24/00) through 00-117 (4/26/00). The mm034 sequence was successfully uplinked on 00-116 (4/25/00) and will begin execution on 00-118 (4/27/00). The mz050 mini-sequence, containing the retry of the two missed MOC focus star scans on 4/28 and 4/30, is scheduled for uplink on 00-118 (4/27/00).

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 19 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm033 and mm034 sequences. Total command files radiated to the spacecraft since launch is 4611.

Upcoming Events:

A bistatic radar experiment, in which the Spacecraft signal will be reflected off the Martian surface to Earth, is on schedule for execution on 5/14/00.

The implementation of the first Radio Science occultation egress scans, replacing the previous fixed-HGA periods for obtaining occultation egress data, is also on schedule for execution on 5/20-5/22/00.

Launch / Days since Launch = Nov 7, 1996 / 1260 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 384 days
Total Mapping Orbits = 4992
Total Orbits = 6595

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm030 sequence executed successfully from 00-104 (4/13/00) through 00-107 (4/16/00). The mm031 sequence also successfully executed from 00-108 (4/17/00) through 00-110 (4/19/00). The mm032 sequence was successfully uplinked on 00-108 (4/17/00) and will begin execution on 00-111 (4/20/00).

A retry of the two missed MOC focus star scans is scheduled for 4/28 and 4/30. The second attempts will utilize an updated scan attitude to account for the gyro bias error propagated when the IMU is switched from low rate to high rate mode for the slews.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 11 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm032 and mm033 sequences. Total command files radiated to the spacecraft since launch is 4592.

Upcoming Events:

A bistatic radar experiment, in which the Spacecraft signal will be reflected off the Martian surface to Earth, is on schedule for execution on 5/14/00, upon Project approval expected next week.

The implementation of the first Radio Science occultation egress scans, replacing the previous fixed-HGA periods for obtaining occultation egress data, are also on schedule for execution on 5/20-5/22/00.

Launch / Days since Launch = Nov 7, 1996 / 1253 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 377 days
Total Mapping Orbits = 4906
Total Orbits = 6509

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm028 sequence executed successfully from 00-97 (4/6/00) through 00-100 (4/9/00). The mm029 sequence also successfully executed from 00-101 (4/10/00) through 00-103 (4/12/00). The mm030 sequence was successfully uplinked on 00-102 (4/11/00) and will begin execution on 00-104 (4/13/00).

Included in the mm028 sequence, was the fifth and last star scan of the current MOC focus campaign, and a 24-hour period of MOLA off-nadir scans of the North and South Poles, on 00-99 through 00-100 (4/8-4/9/00). The spacecraft performance during the final MOC star scan was nominal, but the stars were not seen in the image. Thus two of the five scans resulted in not seeing the stars. All indications are that the missed stars were due to a knowledge error in designing the scans. A retry of the two missing star scans will be scheduled for later in April, with an updated scan attitude.

Spacecraft performance during the MOLA scans was also nominal, with a single STAREX (star processing code) anomaly occurring proceeding the first MOLA off-nadir orbit. A STAREX autonomous reset occurred shortly after the sequence commanded the IMU to high rate mode and issued an intentional bias reset prior to the first off-nadir slew. After the autonomous reset STAREX converged properly and performed nominally for the duration of the MOLA scans.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 16 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm030 and mm031 sequences. Total command files radiated to the spacecraft since launch is 4581.

Upcoming Events:

Planning for the replacement of the monthly fixed-HGA periods for the purpose of obtaining radio science atmospheric occultation egress data, prohibited in normal beta supplement operations due to HGA gimbal constraints, proceeds. The first Radio Science occultation egress scans are scheduled for 5/20-5/22/00. Work has been underway over the last month on determining the feasibility of performing a bistatic radar experiment, in which the Spacecraft signal will be reflected off the Martian surface to Earth. All design hurdles have been cleared and work is now underway to implement this experiment for a May 14 opportunity.

Launch / Days since Launch = Nov 7, 1996 / 1245 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 370 days
Total Mapping Orbits = 4820
Total Orbits = 6423

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm026 sequence executed successfully from 00-90(3/30/00) through 00-93 (4/3/00). The mm027 sequence also successfully executed from 00-94 (4/4/00) through 00-96 (4/6/00). The mm028 sequence was successfully uplinked on 00-95 (4/5/00) and will begin execution on 00-97 (4/8/00). Included in the mm028 sequence, is the fifth and last star scan of the current MOC focus campaign, and a 24-hour period of MOLA off-nadir scans of the North and South Poles, scheduled on 00-99 through 00-100 (4/8-4/9/00). The mm029 sequence is scheduled to be uplinked on 00-99 (4/8/00) and will execute from 00-101 (4/10/00) through 00-103 (4/12/00).

The mz049 mini-sequence, containing the first four MOC star scans, has begun execution. The first three scans have completed to date. The MOC successfully acquired the desired stars from the first scan, but the stars were on the edge of their image. The second scan resulted in the MOC not seeing the stars. On the third scan the stars were acquired but were again on the edge of the image. The spacecraft attitude control errors were very small during each of the scans, leading us to believe there is some kind of knowledge error in the design of the scans, resulting in the stars not being centered in the image. AACS is currently analyzing the data and working with JPL and the MOC team to determine the cause of this error. Depending on the success of the fourth and fifth scans, additional scans may be performed in the next couple of weeks to ensure the MOC focus objective.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 14 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm028 and mm029 sequences. Total command files radiated to the spacecraft since launch is 4565.

Upcoming Events:

Planning for the replacement of the monthly fixed-HGA periods for the purpose of obtaining radio science atmospheric occultation egress data, prohibited in normal beta supplement operations due to HGA gimbal constraints, proceeds. The first Radio Science occultation egress scans are scheduled for 5/20-5/22/00.

Launch / Days since Launch = Nov 7, 1996 / 1241 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 363 days
Total Mapping Orbits = 4734
Total Orbits = 6337

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm024 sequence executed successfully from 00-83(3/23/00) through 00-86 (3/26/00). The mm025 sequence also successfully executed from 00-87 (3/27/00) through 00-89 (3/29/00). The mm026 sequence was successfully uplinked on 00-88 (3/28/00) and will begin execution on 00-89 (3/29/00). The mm027 sequence is scheduled to be uplinked on 00-92 (4/1/00) and will execute from 00-94 (4/3/00) through 00-96 (4/5/00). The mz049 mini-sequence, containing four MOC star scans for the purpose of improving the camera focus, was also uplinked successfully on 00-89 (3/29/00). The first star scan will occur on 00-90 at 14:35:56 GMT on the spacecraft.

The mm028 and mm029 sequences are currently in development. A fifth and final MOC focus star scan will be included in the mm028 sequence. It is intended to repeat the MOC focus scans every six months. Also included in the mm028 sequence is the next MOLA North and South Pole off-nadir scans. The MOLA polar scans will begin at approximately 12:00 GMT on 00-99 (4/8/00). The scans will take place over 12 consecutive orbits to provide complete longitudinal coverage of the poles.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 18 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm026, mm027 and mz049 sequences. Total command files radiated to the spacecraft since launch is 4551.

Upcoming Events:

Planning for the replacement of the monthly fixed-HGA periods for the purpose of obtaining radio science atmospheric occultation egress data, prohibited in normal beta supplement operations due to HGA gimbal constraints, proceeds.

Launch / Days since Launch = Nov 7, 1996 / 1234 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 356 days
Total Mapping Orbits = 4648
Total Orbits = 6251

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm022 sequence executed successfully from 00-75 (3/15/00) through 00-78 (3/18/00). The mm023 sequence also successfully executed from 00-79 (3/19/00) through 00-81 (3/21/00). The mm024 sequence was successfully uplinked on 00-81 (3/21/00) and began execution nominally on 00-82 (3/22/00). The mm025 sequence is scheduled to be uplinked on 00-85 (3/25/00) and will execute from 00-86 (3/26/00) through 00-88 (3/28/00).

Work has begun on the development of a series of MOC star scans to optimize the camera focus. Five total star scans of the Pleiades star cluster will be performed, one scan every other day, with the scan being done on the night-side of the orbit. The scans are currently scheduled on the days of 3/30, 4/01, 4/04, 4/05 and 4/07.

A series of FSW memory readout commands were performed over the last week and a half in order to determine the cause of an increased number of floating point overflow counts since the start of beta supplement operations. The results of the MROs determined that the overflows were coming from the polynomial evaluation function called by the articulation code and were a result of the HGA gimbals passing through 0 and 90 degrees, which is happening frequently during beta supplement due to the HGA management. The overflows appear to be benign and at this time, the SCT is still ascertaining whether any action is required.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 18 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm023 and mm024 sequences. Total command files radiated to the spacecraft since launch is 4533.

Upcoming Events:

MOLA Off-nadir North and South Pole scans scheduled for 4/8 and 4/9

Launch / Days since Launch = Nov 7, 1996 / 1227 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 349 days
Total Mapping Orbits = 4562
Total Orbits = 6165

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm020 sequence executed successfully from 00-63 (3/3/00) through 00-72 (3/12/00). The mm021 sequence also successfully executed from 00-63 (3/13/00) through 00-74 (3/14/00). The mm022 sequence was successfully uplinked on 00-73 (3/13/00) and began execution nominally on 00-74 (3/14/00).

Upon completion of the recent four day fixed-HGA mapping campaign performed last week, which resulted in higher than expected MOLA temperatures, the spacecraft team began looking at ways to fix the temperature problem. Additionally in assessing the first fixed-HGA campaign, it was noted that the actual transitions into and out of fixed-HGA mode of operations from the beta supplement mode of operations, were more complicated than anticipated and resulted in a larger than expected loss of science data from the other instruments. The Spacecraft Team presented at the 3/14 Project Mission Planning meeting alternatives to and options for fixing the current fixed-HGA operations. Fixed-HGA operations were to be performed 4-8 days per month for the express purpose of acquiring Radio Science Earth occultation egress measurements, which are prohibited during normal beta supplement mapping operations due to HGA gimbal constraints. From the Mission Planning meeting the favored option was to eliminate the fixed-HGA operations and perform special slews for a specified number of orbits to provide the desired longitudinal planetary coverage for the radio science occultation egress data, similar to the implementation of the MOLA off-nadir polar observations. Final details are in work and will be presented to the Project Change Board next Tuesday (3/21)

Spacecraft Health:

All subsystems are reporting nominal health. Battery 2 was successfully commanded back to VT-2 after transitioning back to beta supplement operations. The red alarm high limit for the MOLA temperature has been decreased by 3 degrees (from 35°C to 32°C) after a meeting with the MOLA engineers.

Uplinks:

There have been 20 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm021 and mm022 sequences. Two uplinks were missed after the final transition from the fixed-HGA Earth pointed attitude back to nadir pointed beta supplement operations due to a large change in the transponder temperature. The uplink sweeps for the beta supplement orbits are tailored specially for the very short uplink windows and are very sensitive to changes in the MOT temperature. The missing uplinks were successfully re-radiated. Total command files radiated to the spacecraft since launch is 4515.

Upcoming Events:

Planning has begun for a focus calibration of the MOC to be performed in late March.

Launch / Days since Launch = Nov 7, 1996 / 1220 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 342 days
Total Mapping Orbits = 4476
Total Orbits = 6158

Recent Events:

The spacecraft continues to operate nominally in performing the beta supplement daily recording and transmission of science data. The mm018 sequence executed successfully from 00-62 (3/2/00) through 00-65 (3/5/00).

The mm019 sequence (i.e. first fixed-HGA sequence) began execution on 00-65 (3/5/00) and will run through completion of 00-68 (3/8/00). The mm019 sequence contains 12 orbits of MOLA off-nadir polar scans followed by three consecutive days of eight hour fixed-HGA Earth pointed periods, designed to allow radio science Earth occultation egress data, which is prohibited during beta supplement operations due to HGA boom and EMI interference constraints. Two incidents have occurred on the spacecraft during the execution of this sequence, as described below. The next sequence mm020 (another beta supplement sequence), scheduled to execute from 00-69 (3/9/00) through 00-72 (3/12/00), has been successfully uplinked to the spacecraft.

The first incident of the mm019 sequence was with star processing during the MOLA off-nadir Polar scans. The first 12 orbits of the mm019 sequence flew with a -17.1° nadir off-point angle for 45 minutes centered about the South Pole and a 14.4° nadir off-point angle for 45 minutes centered about the North Pole. This left about 30 minutes of star processing time per two-hour orbit. Anticipating that the limited star processing might be problematic, based on the previous MOLA polar scans performed last year, two things were done to ensure that the spacecraft would not lose inertial reference and enter contingency mode fault protection. First a commanded bias reset was issued two hours before the first MOLA scan to coincide with the IMU swap to high rate mode and second the lost logic limit, the number of unidentified stars allowed before an autonomous bias reset, was raised to 60 stars. Twice during the 12 orbit scan sequence, the lost logic limit was exceeded and an autonomous reset was commanded. After each reset the spacecraft successfully converged attitude. Three consecutive cumulative resets are required to actually cause entry into contingency mode. Prior to slewing the spacecraft to the first fixed-HGA Earth pointed attitude following the MOLA scans, the spacecraft attitude was nominal and star processing was properly converged. In spite of the star processing problems, the spacecraft successfully executed all of the slews and returned the data back to Earth, during the subsequent eight hour fixed-HGA Earth pointed period.

The second incident occurred when the MOLA laser temperature approached the 35° upper flight allowable limit, during the last orbit of the second eight-hour fixed-HGA Earth pointed period. The increased temperature was expected but the actual temperatures were about four degrees higher than that predicted by the thermal model. Real-time telemetry was not available for the flight team during the Earth pointed period, which is used for playback of the recorded data. The greater than expected temperature increase was noticed in the playback data on the third and last fixed-HGA Earth pointed period.

The Spacecraft Team is currently reassessing the monthly MOLA off-nadir polar orbit scans and the fixed-HGA Earth periods for radio science egress data, to determine what changes are required to ensure the safety of all the instruments and robustness of the spacecraft in performing these special events. Options will be presented to the Project at the 3/14 Mission Planning meeting. The next fixed-HGA sequence is scheduled for 00-076 (3/16/00) and will most likely be replaced with a beta supplement sequence.

Spacecraft Health:

All subsystems are reporting nominal health. As expected the battery DOD was greater during the four fixed-HGA Earth pointed orbits due to the additional transmitter on time associated with performing the radio science occultation egress event. As a result battery 2 autonomously switched to the VT 1 curve. Upon completion of the fixed-HGA sequence, battery 2 will be commanded back to VT 2.

Uplinks:

There have been 15 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm020 sequence. Total command files radiated to the spacecraft since launch is 4495.

Upcoming Events:

Planning has begun for a focus calibration of the MOC to be performed in late March.

Launch / Days since Launch = Nov 7, 1996 / 1213 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 335 days
Total Mapping Orbits = 4390
Total Orbits = 6072

Recent Events:

The spacecraft continues to operate nominally in performing the daily recording and transmission of the science data. The mm016 sequence executed successfully from 00-55 (2/24/00) through 00-58 (2/27/00). The mm017 sequence began execution on 00-59 (2/28/00) and will run through completion of 00-61 (3/1/00). The next sequence mm018, scheduled to execute from 00-62 (3/2/00) through 00-64 (3/4/00), has been successfully uplinked to the spacecraft.

The first fixed-HGA sequence of the beta supplement mapping phase, mm019, has been generated and will be uplinked Saturday March 4. The mm019 sequence will begin execution on 00-65 and continue through 00-68 (3/8/00). Included in the mm019 sequence is the first of the monthly off-nadir polar scans for the MOLA instrument, approved by the Program. The first 12 orbits of the mm019 sequence will fly with a -17.1 degree nadir off-point angle for 45 minutes centered about the South Pole and a 14.4 degree nadir off-point angle for 45 minutes centered about the North Pole. For the fixed-HGA mapping operations, the spacecraft will be nadir pointed for 24 hours, recording science data on the solid state recorders, then the spacecraft will be oriented to point the HGA bore-sight at Earth for an eight hour playback period to return the data collected on the recorders. During this eight-hour period, the spacecraft will not be nadir pointed and not collecting science data, with the exception of radio science which will perform atmospheric observations as the spacecraft enters and exits Earth occultation. As reported last week the reason for the fixed-HGA sequences is to provide radio science atmospheric observations near the South Pole as the spacecraft exits Earth occultation, a geometry not supported by the HGA gimbals in the beta supplement operations due to EMI and HGA boom interference constraints. Upon completion of the data playback at the end of the eight-hour Earth pointed period, the spacecraft will be turned back to nadir pointing to begin the next fixed-HG A cycle

Spacecraft Health:

All subsystems are reporting nominal health. Three more PDS reset occurred over the last week. The frequency has been increasing over the last two weeks. So far no cause has been found for the recurring resets. The resets appear to have minimal if any impacts to the instruments. We continue to forward all reset data to the PDS software experts at JPL.

Uplinks:

There have been 21 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm017 and mm018 sequences. Total command files radiated to the spacecraft since launch is 4480.

Upcoming Events:

The Navigation team has been looking at the ground track walk on a weekly basis to determine if an orbit trim maneuver (OTM) is required. Prior to the start of beta supplement operations, it appeared that an OTM would be needed sometime in March. However, the latest tracking data for the first few weeks of beta supplement operations shows the rate of the ground track walk decreasing and starting to knee over, which if the trend continues will not necessitate an OTM in the near term. With the likelihood of the next OTM diminishing, planning has begun for a focus calibration of the MOC to be performed in the next few weeks.

Launch / Days since Launch = Nov 7, 1996 / 1206 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 328 days
Total Mapping Orbits = 4305
Total Orbits = 5987

Recent Events:

The pace of the new mapping Beta sequence generation problem, a build every week, and a realization of new operational constraints imposed by the new mapping scheme, has caused two sequencing errors over the last week.
On 00-048 (2/17/2000) at about 00:00 UTC, the new Beta Supplement sequence, mm014b, was scheduled to kickoff but never went active. Since that new sequence controls the tracking of the HGA to Earth, no downlink was possible. Using a 34-m HEF station, a command was successfully uplinked via LGR-2 to change the uplink rate from 125 bps to 7.8 bps. Then, at 7.8 bps, a mini-sequence was successfully radiated to auto-track the HGA for about 30 minutes per orbit for 4 consecutive orbits, allowing for a 4K real-time downlink. During the first of these orbits, spacecraft telemetry was obtained which showed that MGS was in a healthy condition. During the second of these orbits, the uplink rate was changed back to 125 bps and the new mm014c sequence was uplinked to resume normal operations. The mm014c sequence began execution nominally at 14:20 UTC and has successfully completed execution. The mm015 sequence, was uplinked and began execution on 00-051 (2/20/2000) at 00:00 UTC. The mm015 sequence is scheduled to run through 00-054 (2/23/2000). The net effect of the anomaly was the loss of most of DOY 48 recorded science telemetry.
The cause of the mm014 sequence anomaly was that it was loaded into the incorrect area of the sequence buffer, which was already executing the mm013 sequence. This error was induced by having to split the 7 day beta supplement sequence into two parts due to the size of the sequence and the much reduced uplink time available each orbit due to the complex HGA management. This splitting process introduced an ambiguity in the naming convention: mm013a was used for Part 1 of sequence 013 rather than revision level a, and mm013b was used for Part 2 of sequence 013 rather than revision level b. When a second revision of Part 1 was required, mm013c was used, since mm013b was already taken by Part 2. Due to the ambiguity in the naming convention, mm014 was run through SEQTRAN using the FINCON file from mm013c (Part 1) rather than mm013b (Part 2). The result was that mm014b was loaded into the same buffer area as Part 2 of the previous sequence. Since this previous sequence was still executing when mm014b was uplinked, the new sequence did not go active.

To confound matters, due to the current MGS to Earth range, we are not able to support two-way data (uplink and downlink data) at the high rate 40 ksps real-time downlink rate. Therefore all uplinks are currently performed during orbits in which the recorded data from the previous day is being played back. Therefore confirmation of a successful sequence uplink and activation requires waiting until the next day's data is played back. For this case there was insufficient time available to determine that the sequence load had been rejected and to rebuild a replacement sequence in time. This was due in part to a half-day loss in the schedule due to a problem with our spacecraft test lab (STL).
The second anomaly occurred with the development of the mm016a sequence, which was uplinked successfully to the spacecraft on 00-052 (2/21/200) and scheduled to begin execution on 00-055 (2/24/00) at 00:00 UTC. In this event an error in the recording and playback of the science data was discovered after the sequence had been uplinked. The sequence was successfully terminated on 00-054 (2/23/2000) at ~14:00 UTC and a replacement sequence, mm016b, uplinked several orbits afterwards upon confirmation of the termination of mm016a. The root cause for this anomaly was simply a rush to uplink the sequence early enough to verify its activation in order to avoid a repeat of the mm014 sequence anomaly.

Several changes have been made to the sequence development process for the weekly sequence builds. The first change, which was already going to be made for the next sequence anyhow, was to rename the sequences. The split of the weekly sequences into two parts creates two sequences, mm016 and mm017, for example, rather than mm016a and mm016b. The second and probably the most important change made was to increase the sequence development time by three days to provide sufficient time with margin for development, review, STL validation, uplink and verification of the sequences.

One final note, the failure to get a new sequence on-board the spacecraft poses no risk to the health of the spacecraft. The spacecraft will maintain mapping nadir pointing and articulation of the solar array. Communications from the spacecraft and collection of science data will be interrupted until a new sequence can be uplinked.

Spacecraft Health:

All subsystems are reporting nominal health. A sixth PDS reset occurred on 00-019. So far no cause has been found for the recurring resets. The resets appear to have minimal if any impacts to the instruments. We continue to forward all reset data to the PDS software experts at JPL.

Uplinks:

There have been 14 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm014, mm015 and mm016 sequences. Total command files radiated to the spacecraft since launch is 4459.

Upcoming Events:

The first fixed-HGA mapping sequence of the beta supplement era is scheduled for March 6 and development of this sequence has begun. One of the limitations of the mapping beta supplement scheme is a loss of South Pole radio science atmospheric data due to HGA gimbal constraints. The project approved a three to four day period each month to perform fixed-HGA operations, in which the HGA is pointed along the spacecraft +X axis and the spacecraft is moved to point the HGA to Earth for an eight-hour period (i.e. four orbits). During the eight-hour Earth pointed period the science data recorded from the previous 24 hours of nadir pointed mapping is played back. This scheme allow radio science observations to be made at Earth occultation ingress and egress, at the expense of collecting mapping data for the eight-hour Earth pointed period. The project also approved monthly MOLA nadir off-pointed polar observations. These observations will be performed during the 24 hour nadir pointing period prior to the first eight-hour fixed-HGA Earth pointed period.

Launch / Days since Launch = Nov 7, 1996 / 1199 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 321 days
Total Mapping Orbits = 4219
Total Orbits = 5901

Recent Events:

Beta Supplement operations continue nominally. The mm013 sequence is currently executing on the spacecraft. The next sequence, mm014, was uplinked to the spacecraft on Feb 15 at 18:25 GMT and is scheduled to go active at 00:00 GMT on Feb 17.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 30 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm013 sequence. Total command files radiated to the spacecraft since launch is 4445.

Upcoming Events:

The first fixed-HGA mapping sequence of the beta supplement era is scheduled for March 6. More details forthcoming.

Launch / Days since Launch = Nov 7, 1996 / 1190 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 314 days
Total Mapping Orbits = 4134
Total Orbits = 5816

Recent Events:

The mz041 mini-sequence, containing the "full-up" Beta Supplement HGA motion verification test, executed on Thursday Feb 3 at ~11:00 GMT. The test successfully moved the azimuth gimbal to 140°, then performed a "simulated orbit" on the elevation gimbal, incorporating a 3-part boom interference rewind and a 3-part range-of-motion rewind, and executed the full elevation range of motion from -157° to +155°. Based upon the success of the test, the first beta supplement mapping sequence, mm012, was radiated to the spacecraft and began executing Saturday Feb 4 at 00:00 GMT. The first beta supplement orbit executed on Monday Feb 7 at 10:00 GMT and all operations on the spacecraft and with the DSN station were completely nominal. Twenty-five orbits have been successfully executed as of the writing of this report.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 25 uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the mm012 sequence. Total command files radiated to the spacecraft since launch is 4415.

Upcoming Events:

Uplink of the second beta supplement sequence, mm013, is scheduled for Thursday Feb 10.

Launch / Days since Launch = Nov 7, 1996 / 1169 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 293 days
Total Mapping Orbits = 3876
Total Orbits = 5558

Recent Events:

The mm011 sequence began execution on Jan 13 at 00:00 UTC and runs through Feb 4. The spacecraft continues to perform flawlessly in performing the nominal mapping mission.

The mz035 mini-sequence, containing scans for a third Pathfinder landing site image and two additional MPL landing site images finished execution on Jan 19 at 13:45 UTC. Unfortunately, bad luck struck again with regard to the Pathfinder opportunity and significant portions of the Pathfinder image were lost due to more DSN problems. There is no redundant capability to return the imaging data at the high 40000 bps real-time rate and also record the data to the solid state recorders for redundant playback the next day. Consequently, return of these landing site images is a single opportunity event which requires the DSN stations to be configured and working properly during the ~30 minute data return period. Hardware, weather and other factors with the stations contribute to make this far from a foolproof process. In general, the DSN has performed excellently in supporting the MGS mission.

A change request was approved by the Project to perform some HGA motion calibration tests for the Magnetometer team. These will be performed on the dark side of the planet and will have minimal effect on normal operations. The only exception is that Radio Science ingress data will be prematurely truncated on the calibration orbits. These HGA motions tests will be performed over 15 orbits, with the solar arrays being moved to different fixed positions during the HGA motions after every three orbits. Due to mini-sequence buffer size constraints, the 15 orbits will be performed in two parts. The mz036 mini-sequence was successfully transmitted to the spacecraft on Jan 19, to perform the first 9 orbits on Jan 20 and mz037 will be transmitted on Jan 21 to perform the remaining 6 orbits on Jan 21.

The Ka Band Link Experiment (KaBLE) was turned off on Jan 14, to reduce the spacecraft power loads. The KaBLE investigators are not currently utilizing the Ka Band data.

HGA Anomaly:

The HGA inner gimbal continues to decrease and is currently at 48.9 degrees. The inner gimbal angle will continue decreasing, reaching the location of the gimbal obstruction at 41.5 deg in early February. A special review was held on Jan 18 to discuss possible spacecraft testing to determine if the obstruction is still present. The recommendations from the review are expected by the end of the week. Any spacecraft testing would be performed over the next two weeks, prior to the start of beta supplement mapping operations.

Spacecraft Health:

All subsystems are reporting nominal health. A third Payload Data System (PDS) reset occurred on Jan 16. The reset data has been sent to JPL, who designed and built the PDS. The spacecraft team has been unable to correlate the data to any specific spacecraft activity.

Uplinks:

There have been 27 uplinks to the spacecraft during the last two weeks, including new star catalogs and ephemeris files, instrument command loads, KaBLE turn off and the mz036 mini-sequence load. Total command files radiated to the spacecraft since launch is 4345.

Upcoming Events:

The preliminary first beta supplement sequence will begin development Jan 20 in preparation for the start of beta supplement mapping operations on Feb 5. Additional MPL and MPF imaging opportunities will continue through Feb 4. The next imaging mini-sequence will be built on Jan 21 and will contain all the desired over-flight opportunities through Jan 26.

Wednesday, January 12, 2000 (DOY 005/19:00:00 to DOY 012/19:00:00 UTC)

Launch / Days since Launch = Nov 7, 1996 / 1162 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 286 days
Total Mapping Orbits = 3791
Total Orbits = 5473

Recent Events:

The mm010 sequence finishes execution on Jan 13 at 01:27 UTC. The next mapping sequence, mm011, has been uplinked to the spacecraft and will begin execution on Jan 13 at 00:00 UTC and continue executing through Feb 4. The mm011 sequence will be the last nominal mapping sequence of the baseline mapping mission. The next mapping sequence will be the first of the new beta supplement sequences, designed to continue mapping operations in the presence of the HGA obstruction at the 41.5 deg azimuth gimbal angle. Stay tuned for more information about the specifics of beta supplement mapping operations over the next few weeks

The mz034 mini-sequence was uplinked to the spacecraft on Jan 8 and finished execution on Jan 12 at 09:00 UTC. The mz034 sequence contained the second imaging scan of the Pathfinder landing site and four additional scans of the Mars Polar Lander landing site. The additional MPL landing site scans are intended to fill in gaps in the original imaging campaign performed prior to the holidays and to expand the coverage area to the west in response to the latest atmospheric data. Unfortunately bad luck asserted itself again on the second Pathfinder landing site image as the science data was lost due to DSN station problems. A third attempt to image the Pathfinder site is currently being planned. Additional imaging of the MPL landing site is currently being discussed to continue expanding the coverage area.

The spacecraft continues to behave flawlessly in performing nominal mapping operations and the multitude of imaging scans.

HGA Anomaly:

The HGA inner gimbal continues to decrease and is currently at 51.7 degrees. The inner gimbal angle will continue decreasing, reaching the location of the gimbal obstruction at 41.5 deg in early February. STL testing to validate the new beta supplement operations plan continues.

Spacecraft Health:

All subsystems are reporting nominal health.

Uplinks:

There have been 18 uplinks to the spacecraft during the last two weeks, including new star catalogs and ephemeris files, instrument command loads and the mm011a and mz034a sequences. Total command files radiated to the spacecraft since launch is 4318.

Upcoming Events:

1) The mm012 sequence development kickoff meeting is scheduled for Jan 18.

2) The mz035 mini-sequence to continue imaging the MPL and MPF landing sites is scheduled for development on January 13 and 14.

3) The mz036 mini-sequence to perform additional magnetometer instrument calibrations has been approved and will begin development Jan 17.

Launch / Days since Launch = Nov 7, 1996 / 1155 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 279 days
Total Mapping Orbits = 3707
Total Orbits = 5389

Recent Events:

The mm010 sequence continues executing nominally the daily science record and playback events. The mm010 sequence runs through January 12.

The initial MPL landing site imaging campaign has been completed, with 19 targeted scans across the predicted 1-sigma MPL landing ellipse having been executed. Unfortunately no obvious signs of the lander or its parachute has been found at this time. Note that the definition of the landing ellipse continues to change as additional atmospheric data from MGS is factored in. As a result, the current landing site imaging mosaic may not reflect the latest landing site knowledge. Additionally there were some gaps in the mosaic due to lost data at the DSN stations. As a result, a second set of imaging scans is being planned to fill in the gaps and to expand the coverage area in response to the latest atmospheric data.

In addition to completing the MPL scans, a special targeted opportunity to image the Mars Pathfinder landing site was performed Sunday December 26 at 09:18 UTC. Unfortunately due to an error in the coordinate system used to derive the targeted attitude, the wrong site was imaged. A second opportunity to image the Pathfinder landing site occurs on Sunday January 9. The mz034 mini-sequence will be built on January 6 and 7 to perform the MPF and additional MPL landing site imaging, and will execute through January 12.

The spacecraft has behaved almost flawlessly in performing all of the imaging scans.

HGA Anomaly:

The HGA inner gimbal angle continues to decrease and is currently at 53.5 degrees. The inner gimbal angle will continue decreasing, reaching the location of the gimbal obstruction at 41.5 deg in early February. STL testing begun for validation of the HGA beta supplement operations plan, which will be used to perform mapping operations for the rest of the nominal mapping mission.

Spacecraft Health:

All subsystems are reporting nominal health. As reported previously, battery 2 switched from VT curve 2 to VT curve 1 as a result of performing the MPL scans. This was expected and resulted in slightly higher battery 2 temperatures. Upon completion of the initial MPL and MPF scans, the Battery 2 VT curve was switched back to VT2. Soon after though the flight software autonomously re-commanded battery 2 back to VT1, which is where we will leave it. The trend indicates that battery 1 will shortly switch to VT1 as well.

Uplinks:

There have been 42 uplinks to the spacecraft during the last two weeks, including new star catalogs and ephemeris files and instrument command loads. Total command files radiated to the spacecraft since launch is 4300.

Upcoming Events:

1) The mm011 sequence is currently in development and is scheduled for uplink Monday January 10, with a sequence start time of January 13 00:00 UTC.

2) The mz034 sequence to continue imaging the MPL and MPF landing sites is scheduled for development on January 6 and 7, to begin execution on Sunday January 9.

MSOP-MGS Status Reports for 1999