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MSOP Status Report Overview

Prepared by Mars Surveyor Operations Project Manager

NASA Jet Propulsion Laboratory

 

Friday 17 September 1999

Mars Climate Orbiter performed the fourth and final course correction, TCM-4, on Tuesday, September 14. The objective of the 1.37 m/s maneuver was to place the spacecraft on its final approach trajectory to Mars. Spacecraft performance was
excellent, and the updated gimble angle trajectory for the stow/unstow movements of the solar array worked as expected.

Final preparations for next weeks Mars Orbit Insertion are continuing. Flight team activities include a complete audit of the flight processor's file, development and validation of the final sequence products, and close-out of action items resulting from last week's Operational Readiness Review. Round-the-clock flight team staffing will start on Monday, September 20.

Mars Polar Lander and Mars Global Surveyor continue to operate quiescently with no significant events to report.


Friday 03 September 1999

The Mars Polar Lander spacecraft successfully completed the Site Adjustment Maneuver this week. The objective of this maneuver was to target the vehicle to the selected 76°S, 195°W landing site. Early telemetry and tracking results indicate very small execution errors, but additional tracking will be required before the final results of the maneuver are known.

The flight team successfully conducted two critical events reviews for Mars Climate Orbiter. The purpose of these reviews were to assess the readiness of the flight system to perform Mars Orbit Insertion and aerobraking activities.


Friday 27 August 1999

Several major milestones were completed this week as we continue our preparations for the arrivals of Mars Climate Orbiter and Mars Polar Lander at Mars. On the Orbiter, two separate in-flight checkouts were conducted to exercise both the primary solar array encoder and inner gimbal drive. Anomalous behavior observed after TCM-3 led us to conduct a set of troubleshooting tests which indicated that both the encoder and gimbal are working normally. Evaluation of the post-TCM3 problem is now focusing on the specific series of movements required to move the solar array in and out of the passive restraint. A special test is scheduled for next week to revalidate this process.

The flight team successfully conducted its second Operational Readiness Test for MCO aerobraking this week. While a few minor problems were encountered, this test fully validated the operational plans, procedures, and tools that will be used for aerobraking.

On Tuesday, August 24, NASA HQ formally approved the target landing sites for Mars Polar Lander and Deep Space 2. This approval followed a briefing to senior Office of Space Science management. The selected target zone for Mars Polar Lander is centered at 76 deg S, 195 deg W, with the DS-2 site approximately 50 km north. The flight team is currently developing the Site Adjustment Maneuver sequence required to target the vehicle to this site. This maneuver will be executed next week.


Friday 20 August 1999

All missions continue to perform quiescent operations. The project reached consensus this week on the observation strategy that Mars Global Surveyor will use after normal mapping ends in February 2000. The new strategy involves a combination of fixed high gain mapping and the so-called beta supplement mode. The expectation is that new strategy will allow us to minimize the data loss during this period within available resources.

The flight team conducted its first Operational Readiness Test (ORT) in preparation for MCO aerobraking this week. The test was successful, largely as a result of the experience the team has from MGS aerobraking. An additional test has been scheduled for next week to further tune up our processes, procedures, and tools.


Thurday 12 August 1999

All missions continue to perform quiescent operations. Mars Global Surveyor successfully complete the third Orbit Transfer Maneuver since mapping started. The purpose of this maneuver was to correct ground track drift and ensure uniform mapping coverage. The flight team started test and training activities for Mars Climate Orbiter arrival this week with a Mars Orbit Insertion/Period Reduction Maneuver Operational Readiness Test. Configuration errors in the System Test Lab caused problems with the MOI portion of the test, but the PRM planning activity went as planned. An additional ORT is being planned to correct and validate the MOI procedure.


Friday 05 August 1999

All missions continue to perform quiescent operations. The flight team commanded Mars Climate Orbiter out of safe mode late last week, and continues to assess potential causes for the solar array gimbal encoder problem. The team is currently planning to conduct some gimbal wiggle tests over the next few weeks to obtain additional troubleshooting data.

The project completed a very successful Landing Site Certification Review for Mars Polar Lander this week. The objectives of the review were to assess the certification process and obtain review board concurrence with the project's recommended sites. The review board unanimously agreed that the objectives were met, and the stage is now set for final site selection later this month. The project also conducted a successful review of its' public affairs plans for MPL/DS-2 arrival this week with JPL, NASA HQ, and UCLA PIO personnel. No major issues were identified, but considerable work is still required to flesh out the details of the plan.


Friday 16 July 1999

All missions continue to perform quiescent operations. This week's key activity was the successful completion of the first planned Operational Readiness Test (ORT) for Mars Polar Lander surface operations. The flight team has scheduled a number of ORT's over the next few months to validate our operational processes, procedures and contingency plans. In this test, the team used the MPL System Test Lab at Lockheed Martin to simulate spacecraft activities during the first three days of surface operations. All nominal ground activities were performed in parallel including simulated command activities. The flight team spent the final two days of the test performing the standard two day sequence build process. The objective of this process was to build a new sequence for Sols 4&5, and this is the first time that the science, spacecraft, and sequence teams have collaborated to build a new sequence from scratch using the actual flight timeline.


Friday 1 July 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations with no significant events to report.

Mars Global Surveyor

Mars Global Surveyor continues to perform quiescent mapping operation with no significant events to report.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations. This week's key activity was the successful completion of the first planned Operational Readiness Test for Entry, Descent, and Landing operations. The flight team has scheduled a number of ORT's over the next few months to validate the operational processes and procedures required to perform EDL. In this test, the team used the lander System Test Lab at LMA to simulate spacecraft activities during the final 29 hours before entry. All nominal ground activities were performed in parallel including the final pre-entry command activities. This test will be repeated several times before landing, with later tests incorporating possible contingencies.


Friday 25 June 1999

Mars Climate Orbiter

Mars Climate Orbiter achieved a significant milestone this week with the final transition to all stellar mode attitude control. Spacecraft attitude determination is performed using only the star camera in this mode. The gyros (which have been on since launch) can be powered down, which helps to extend their life. Although gyro lifetime is not a major concern, transition to all stellar mode will help reduce overall project risk. All stellar mode implementation has proven to be more complex than originally thought, and the LMA spacecraft team has done an excellent job developing and validating this new capability.

Mars Global Surveyor

Mars Global Surveyor continues to perform quiescent mapping operation. The primary objective of imaging observations during this phase is the Mars Polar Lander landing sector near the South Pole. The MOC team has done an excellent job blanketing the sector with images, and we will shortly have all the information needed to make the landing site selection.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations with no significant events to report.


Friday 11 June 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations with no significant events to report.

Mars Global Surveyor

Mars Global Surveyor continues to perform quiescent mapping operation. The first scheduled science campaign (focusing on geodesy investigations) was successfully completed this week.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations with no significant events to report.


Friday 28 May 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations with no significant events to report.

Mars Global Surveyor

The Mars Global Surveyor spacecraft continued normal mapping operations this week as part of Science Campaign A. A summary of last week’s MGS science meeting has been prepared and will be distributed to JPL and NASA management. This summary will be the first of a monthly series of reports that summarize on-going science activities on MGS.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations with no significant events to report.


Friday 21 May 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations. Preliminary analysis of data received from last weeks UHF test indicates that the spacecraft signal was received at the Stanford 40 m antenna.

Mars Global Surveyor

The Mars Global Surveyor spacecraft continued normal mapping operations this week as part of Science Campaign A. The only notable event of the week was an autonomous transition from the normal set of High Gain Antenna Gimbal Drive Electronics to the redundant side. This transition was caused when the difference between the desired and actual position of either the azimuth or elevation gimbal exceeded the expected level. The flight team is assessing the source of the switch, including any possible correlation with prior gimbal problems. Ground commands were sent to switch back to the nominal side, however, and the HGA is now functioning normally.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations with no significant events to report.


Friday 14 May 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform nominally and is now more than halfway through its trip to Mars. The only significant operational task performed this week was a retest of the UHF contact sequence. The purpose of this test was to have the orbiter simulate the initiation of a contact session with the lander and use Stanford University's
40 m antenna to detect the transmitted signal. The Stanford antenna is used to record signals in the orbiter’s broadcast band in an effort to detect the "ping" waveforms transmitted by the orbiter. A second test had to be scheduled to correct problems with the Stanford receiving hardware and validate changes in the sequence needed to work-around EMI induced problems with some battery sensors. In an actual UHF session at Mars, the lander would respond by "pinging" back to the orbiter; subsequently data transfer between the two spacecraft would commence. The orbiter performed as expected during the test. Post-processing of the recordings made by the Stanford 40 m dish have begun, but will likely take several days before results are available.

Mars Global Surveyor

The Mars Global Surveyor spacecraft continued normal mapping operations this week. The first of six scheduled science campaigns has started, focusing on acquiring stereo image mosaics and high resolution laser altimetry.

Mars Polar Lander

Mars Polar Lander continues to perform quiescent cruise operations with no significant events to report.


Friday 7 May 1999

Mars Global Surveyor

The Mars Global Surveyor spacecraft resumed normal mapping operations this week. The required position of the HGA azimuth gimbal is greater than 42°, so the new obstruction does not cause a problem. All instruments are on and functioning normally. On Friday, May 7, the spacecraft performed the first Orbit Transfer Maneuver since the start of normal mapping. The objective of this maneuver is to correct the ground track repeat pattern prior to the start of Science Campaign A. The maneuver required a velocity change of 3.5 m/s, and was performed using the hydrazine system. The ground track has now been changed to obtain the desired 58 km walk after the 88 orbit repeat pattern. Science Campaign A (focused on geodesy) started on May 6, and will continue for the next four weeks.

For Mars'98 Status See:

http://mars.jpl.nasa.gov/msp98/news/status.html


Friday 23 April 1999 5:49 PM -- Update by MSOP Flight Team

Troubleshooting the HGA azimuth gimbal continued this week. The gimbal is acting as if there is a hard stop at 41 deg. We believe that the gimbal can provide motion from 41 to 80 deg which would support nominal mapping from May 6 through February of 2000. All indications are that the elevation gimbal operates normally through its full range of motion.

Plans are being made to turn on the instruments on Wednesday, April 28 and to resume fixed HGA mapping on Thursday, April 29. Nominal mapping is planned to begin on Thursday, May 6 when the Earth angle from the orbit plane reaches 41 deg. An OTM is planned for Friday, May 7 to adjust the groundtrack walk to the nominal 58.6 km. If the gimbal obstruction is not resolved, we will need to return to fixed HGA mapping in February 2000. Some options exist to permit nominal mapping in the last few months of the mapping phase, in late 2000 and early 2001.

Joseph Beerer

MGS Flight Operations Manager


Friday 9 April 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations with no significant events to report.

Mars Global Surveyor

Mars Global Surveyor initiated normal mapping operations on Sunday, April 4. The spacecraft is now in the nadir pointed configuration with the High Gain Antenna tracking the Earth. The spacecraft and instruments have been operating nominally, but the combination of a sequence error and DSN tracking problems have caused several small gaps in the returned data. As of Friday, April 9, these problems appear to have been completely resolved and all acquired data is being successfully returned.

Mars Polar Lander

Mars Polar Lander completed the first of two planned health checks of the science instruments on Wednesday, Apr. 7. All instruments were powered up and performed their operations as expected. Analysis of the downlink data indicates that the overall health of the instruments is excellent.


Friday 2 April 1999

Mars Climate Orbiter

Mars Climate Orbiter continues to perform quiescent cruise operations with no significant events to report.

Mars Global Surveyor

Mars Global Surveyor achieved a major milestone this week with deployment of the High Gain Antenna on March 28. The HGA can now be pointed at Earth while the spacecraft collects science data in the nadir pointed configuration. The hinge damper worked fine, and the undamped motion occurred over a much smaller range than worst case estimates. After successful deployment, the flight team performed several calibration activities to ensure that the gimbals could point the antenna accurately. On Thursday, April 1, the spacecraft was placed in the nominal nadir pointing configuration and began using the horizon sensor to control the attitude. On April 2, the instruments will be powered back on and normal mapping operations will commence.

Mars Polar Lander

Mars Polar Lander continues to perform cruise operations with no significant events to report.

3:35 PM Update: MSOP Flight Team

The MGS science instruments were turned on this morning in preparations for the start of mapping operations. The instruments were turned off last Sunday in order for the spacecraft to deploy its high gain antenna. The antenna deployment went smoothly and the antenna is now tracking the earth at the end of its 6-foot long boom.

Yesterday morning the flight team, for the time, commanded the spacecraft to use the Horizon Sensor to control its attitude. This device observes the atmospheric limb of Mars to determine roll and pitch attitude errors and keeps the spacecraft and instruments pointed to the center of the planet.

The first month-long mapping sequence was uplinked to the spacecraft this morning. This sequence will begin to control the spacecraft at 4:00 pm PST this afternoon. The sequence calls for continuous recording of science data with daily playbacks during 10-hour tracking passes. Every third day, a second tracking pass will allow the spacecraft to return high rate imaging and spectrometer data in real time. The mapping operations will continue for nearly one Mars year, through January of 2001.

Joseph Beerer

MGS Flight Operations Manager


Friday 26 March 1999

Mars Climate Orbiter

The first of two comprehensive instrument checkout activities was accomplished by MCO on March 24, when the Pressure Modulator Infrared Radiometer (PMIRR) was powered on for a test of its operational modes. The test was successful and the PMIRR team reported that the instrument performed well in all respects. A second checkout sequence to test the MARs Color Imager (MARCI) will be run on March 26. In this test MCO will conduct a series of four slew maneuvers allowing MARCI to acquire images of bright target stars, providing data for calibration of the instrument's optics train and CCD detector circuitry.

Mars Global Surveyor

Mars Global Surveyor continues to perform contingency mapping using the fixed High Gain Antenna. Sequence development and validation is underway for the HGA deployment, now scheduled for 9:30 P.M. (PST) on March 28. The flight team is also investigating small gaps which have started to appear in the downlink data since the start of contingency mapping.

Mars Polar Lander

Mars Polar Lander continues to perform cruise operations with no significant events to report. Navigation analysis indicates that the arrival coordinates achieved by the Trajectory Correction Maneuver performed last week (TCM-2) were close to the target values.


Friday 19 March 1999

Mars Climate Orbiter

Mars Climate Orbiter continues quiescent cruise operations and the overall spacecraft health is excellent. Checkout of the science instruments is scheduled for next week.

Mars Global Surveyor

Mars Global Surveyor continues to perform contingency mapping using the fixed High Gain Antenna. Detailed planning and sequence development is underway for the HGA deployment, now scheduled for the evening of March 28. The MOC team has started to release images from the contingency mapping phase, and all investigators are presenting science results from the aerobraking phase at the LPSC.

Mars Polar Lander

Mars Polar Lander successfully performed its second midcourse maneuver, TCM-2, on Monday, March 15. Spacecraft performance during the maneuver was excellent, and post-maneuver navigation estimates of the flight path indicate the maneuver was implemented well within the allowable execution error envelope. MPL is now operating under control of its third housekeeping sequence, and is successfully employing the updated attitude control strategy developed during February and for which the needed commanding was accomplished last week.


Friday 5 March 1999

Mars Climate Orbiter

On Thursday, March 4th, Mars Climate Orbiter successfully performed the second of four planned course corrections, designated as TCM-2. At 5:35 A.M. (PST), the spacecraft initiated a turn to the correct attitude for the maneuver, then fired its four maneuvering engines for 8.2 seconds, changing its speed by just 0.86 m/s (1.9 mph) to fine tune its flight path. The spacecraft performed as expected in all respects, returning to its nominal orientation for cruise within 10 minutes after completion of the maneuver. The next course correction is scheduled for July 25, approximately two months prior to arrival.

Mars Global Surveyor

Mars Global Surveyor is performing a one week MOC calibration and focus activity that will be completed by Monday, March 8. Early indications were that the camera was nearly focused, and that only minor tweaks in the heater configuration would be requiredq. Stray light calibration tests will be performed over the next two days. The flight team is preparing for a three week period of fixed HGA mapping operations that will commence on March 9.

Mars Polar Lander

Mars Polar Lander continues in quiet cruise. The spacecraft health is excellent. The meteorology sensor package was powered on for its second in-flight calibration and health check on Monday, March 1. Telemetry from this activity was as expected. The flight team has started preparations for the second planned trajectory correction maneuver, currently scheduled for March 15th.


Friday 26 February 1999

Mars Climate Orbiter

Mars Climate Orbiter continues in quiet cruise with nothing significant to report. The spacecraft health is excellent. The flight team is now preparing the command sequence for the orbiter's second course correction, TCM-2, scheduled to take place early on the morning of March 4th.

Mars Global Surveyor

On Wednesday, February 24th, Mars Global Surveyor performed a test of the nadir panel down orientation (pointing the instruments toward the planet) - the orientation required for mapping. During the initial portion of the test, an interaction between the 0.17 Hz natural frequency of the damaged -Y solar panel yoke structure and the attitude control system was observed. Because of the resultant increased activity of the X and Z axis reaction wheels, the rest of the test sequence was canceled. Filter parameters in the attitude control system were modified to notch-out the frequency of concern, and the test was rerun on Friday, February 26th. The results were very favorable. Turn-on of the remaining science instruments (Mars Orbiter Laser Altimeter, Mars Orbiter Camera, and the Thermal Emissions Spectrometer) has been delayed from February 26th to February 28th. A week of focus and calibration of the Mars Orbiter Camera will follow.

Mars Polar Lander

Mars Polar Lander continues in quiet cruise. The spacecraft health is excellent. On Friday, February 26th, the descent engine valves were opened and the propellant lines were vented to space. This event is timed such that the navigation team has approximately two weeks to observe any resulting effect on the flight path prior to the TCM-2, scheduled for March 15th.


Friday 19 February 1999

Mars Global Surveyor

Mars Global Surveyor has completed its two-week gravity calibration period and has successfully executed a 22 m/s bipropellant maneuver to transfer to the mapping orbit orbital parameters on Friday afternoon (2/19/99). Earlier in the week, solid state recorder 2A apparently shut off by itself. Power cycling restored power consumption and functional testing of the unit will be accomplished later today. Otherwise, the spacecraft is performing normally. The coming week will see a flight software update for mapping and a one-day operational test of the mapping (nadir panel toward the planet) orientation.

Mars Climate Orbiter

Mars Climate Orbiter continued in semi-quiet cruise operations during the past week.

Additional diagnostic telemetry from Inertial Measurement Unit (IMU)-A was down-linked last week in further support of the investigation into noise characteristics of the ring-laser gyro control loops. Further testing is underway by the manufacturer to characterize the circumstances in which the noise phenomena is observed and to identify its cause.

Commands were also sent to the spacecraft to obtain some specialized telemetry designed to map the unused space in the telemetry buffer. These maps are being used to formulate a "housekeeping" strategy for managing the buffer free space, limiting its fragmentation.

On Tuesday, February 16, a simple test of the UHF transceiver was performed. With the orbiter in its cruise attitude, the transceiver was powered on and commanded into its nominal receive mode, in which it begins transmitting short "ping" waveforms of 150 ms duration every 3 seconds The transceiver was powered for approximately 2 hr; the X-band link with real-time telemetry was maintained throughout this period. A 46 m radio astronomy station operated by Stanford University was configured to attempt detection of the UHF-band "pings" through several different means. Spacecraft telemetry indicated nominal operation of the transceiver during this period; however, power and temperature telemetry from components located near the UHF antenna displayed an unpredicted pattern of quasi-cyclic noise spikes due to the UHF radio operation. After the transceiver was powered off all real-time telemetry returned to nominal values. The Stanford antenna was unable to detect the "ping" wavetrain in real time (the probability of doing so was not considered to be high for the detection methods attempted and due to the line of sight blockage of the spacecraft’s UHF antenna in the cruise configuration). The flight team is currently evaluating telemetry from this test to better understand the interactions observed.

Mars Polar Lander

The Mars Polar Lander spacecraft continues to perform well in early cruise.


Friday 5 February 1999

Mars Global Surveyor

Mars Global Surveyor completed aerobraking at 12:11 AM PST on February 4th with a 61.9 m/s bipropellant main engine burn. The orbit is now sun synchronous, 1.97 hours in duration, inclined at 93 degrees, with a local solar mean time of 2:04 AM - all as desired. (Orbital parameters will change slight during the next few weeks until the transfer to mapping orbit maneuvers.) The Magnetometer / Electron Reflectometer has been turned on again (after having been off since January 28th to enable the sequence margins required for the aerobraking walkout of the atmosphere period). The spacecraft is in excellent health and is now in a two week long gravity calibration period in preparation for mapping operations.

Operations contingency plans were invoked on Tuesday evening, February 2nd, when a water main broke in the building where the Mars Surveyor Operations Project spacecraft operations mission support area is located at Lockheed Martin Astronautics in Denver. All data and voice communications were lost between JPL and that facility. As part of the contingency plan execution, two key spacecraft team engineers were flown to JPL, spacecraft health monitoring, spacecraft commanding and sequence processing capabilities were enabled at JPL with the support of the MSOP and TMOD staffs. Limited capabilities at Denver were reestablished within 12 hours. Voice communications were handled by cell phones and data exchange with JPL was transferred to the commercial Internet. It is a credit to all involved that no spacecraft operations were compromised, and no scheduled events were missed or modified during this incident while performing the most critical events of the MGS aerobraking campaign.

Mars Climate Orbiter

Mars Climate orbiter continues in quiet cruise and in excellent health. The Pressure Modulator Infrared Radiometer instrument was powered on briefly this week to check that the previous cooler door opening event was successful. The instrument’s detectors indicated temperatures that are consistent with the door being open.

Mars Polar Lander

Mars Polar Lander continues in quiet cruise and in excellent health.


Friday 29 January 1999

Mars Global Surveyor

Mars Global Surveyor has begun the walk-out phase of aerobraking. This process was triggered by the apoapsis altitude reaching 1000 km, and consists of 4 small propulsive maneuvers (~1 m/s) conducted approximately every 24 hours to maintain an orbital lifetime of greater than 48 hours while the orbital period approaches 2 hours. The drag passes are occurring over the south polar areas where the atmospheric conditions are quite variable. This will cause some variability in the timing of the maneuvers. At this writing the final termination maneuver (~61 m/s) will occur mid-day on Wednesday, February 3rd. The magnetometer/electron reflectometer instrument as been turned off as planned. The spacecraft continues to be in excellent health.

Mars Climate Orbiter

Mars Climate Orbiter continues in quiet cruise mode with nothing significant to report.

Mars Polar Lander

Mars Polar Lander conducted a set of spacecraft turns to characterize the effects of different sun lighting conditions on the performance of it's star cameras. This data will be used to select spacecraft orientations that will provide for more reliable star camera operation. The spacecraft continues in excellent health.


Friday 22 January 1999

Mars Polar Lander

The Mars Polar Lander Trajectory Correction Maneuver -1 was executed as planned, on Thursday morning, 1/21/99 at 12:30 UTC. All events were nominal. The spacecraft was out of contact for less than 20 minutes: during the slew to the burn attitude, the maneuver, and slew back to earth point. There was no difficulty locking onto the signal after the burn. Spacecraft health was excellent after the burn, and real-time doppler data indicated that the maneuver was very close to predicts.

Mars Climate Orbiter

The Mars Climate Orbiter continues in quiet cruise with nothing significant to report.

Mars Global Surveyor

Aerobraking continues with increasing frequency as the orbit period and apoapsis altitude approach the desired values as MGS enters its last two weeks of aerobraking. On January 30, 0600 UTC, the critical aerobraking walkout phase begins. During this phase there will be daily propulsive maneuvers to gradually raise the orbit out of the atmosphere. These maneuvers are critical because if they are not performed the orbit will decay and the spacecraft will crash into Mars within 48 hours. The walkout phase ends on February 4, 1200 UTC, with the execution of the aerobraking termination maneuver, ABX. During the walkout phase there will be twice a day uplinks of critical aerobraking sequences that control the spacecraft during the drag pass. The spacecraft will be in a two hour orbit. So there will be 12 orbits and 12 drag passes per day. (The times given above can change by plus or minus 24 hours as a function of aerobraking performance and gravity effects in these last orbits.) The MGS spacecraft continues in excellent health.


Friday 15 January 1999

Mars Polar Lander Mars Polar Lander continues in a healthy cruise state. During the past week, the flight team restarted normal attitude control processing using the star camera, successfully corrected a software bug in the on-board attitude control software that caused excessive thruster activity at attitude control mode changes, and slewed the spacecraft to the modified earth point orientation that is the nominal orientation for the start of its trajectory correction maneuver. As the result of the amount of flight team support required for these three activities, the first trajectory correction maneuver, previously scheduled for Monday, January 18th, has been put off until Thursday, January 21st, with very minimal effect on the fuel required. Future activities, in addition to the trajectory correction maneuver, will include spacecraft reorientations to assess stray light impacts on the star camera performance, and reconfiguring the spacecraft state for the long term early cruise conditions.

Mars Climate Orbiter Mars Climate Orbiter continues in a minimal activity cruise state with minimal DSN tracking. The spacecraft is very healthy.

Mars Global Surveyor Mars Global Surveyor continues in the final weeks of aerobraking. With the end of aerobraking in sight, the weekly aerobraking control operations will deviate from the previous strategy of managing primarily the dynamic pressure, to a more intense assessment of the other factors contributing to the final orbit conditions. These include local mean solar time, orbital inclination, apoapsis altitude reduction increments, as well as dynamic pressure. Current aerobraking perform indicates a slightly earlier conclusion of aerobraking with the current estimate of walkout beginning on January 31st and termination of aerobraking on February 5th. At the time of this writing (1/15/99 @ 3 PM PST), MGS is in its 1079th orbit with an orbital period of 2.85 hours. The spacecraft is very healthy.


Friday 8 January 1999

Mars Polar Lander Mars Polar Lander is now in a nominal cruise mode with the sun and stars acquired and proper medium gain antenna pointing. Earlier issues with the lack of star camera performance have been attributed to scattered light saturation of the star camera. Reconfiguration commanding on Wednesday morning, 1/6/99, allowed the spacecraft to reenter the post separation sequence during which the sun lighting conditions allowed proper star camera operation. There have been two incidents involving rapid rates (rapid transitions within deadbands) that used a quite a bit of fuel. These incidents have been attributed to parameters that needed fine tuning within the attitude control flight software, and are being updated. The spacecraft is very healthy and performing normally.

Mars Climate Orbiter The Mars Climate Orbiter is very healthy, is in a minimal activity cruise mode, with DSN tracking only three hours per day. The Pressure Modulator Infrared Radiometer (PMIRR) instrument team reports that their analysis indicates that the PMIRR cooler door open on command.

Mars Global Surveyor Mars Global Surveyor continues with excellent aerobraking performance. The orbital period is under three hours. The spacecraft is very healthy.


Wednesday 30 December 1998

Mars Climate Orbiter Early cruise operations with the Mars Climate Orbiter (MCO) continue without concern. The spacecraft health is excellent.

Mars Global Surveyor Aerobraking operations continue with good reduction in orbital period each orbit. The backup central computer was returned to normal operations from contingency mode on Wednesday afternoon, December 30th, without incident. The spacecraft is in excellent health.

With the beginning of the eclipse season today, safe mode, the spacecraft’s deepest level of fault protection, will be disabled for the remainder of aerobraking since the spacecraft power state commanded by the safe mode firmware cannot be supported. This is a consequence of the additional year of aerobraking which is now being conducted at a greater distance from the sun than was provided for in the pre-launch design of the safe mode configuration.

Mars Polar Lander All pre-launch preparations for the Mars Polar Lander have been completed, and the flight team awaits launch.


Wednesday 23 December 1998

Mars Climate Orbiter The Mars Climate Orbiter (MCO) continues in its early cruise period in excellent health.

The spacecraft executed its first trajectory correction maneuver successfully on December 21st. The 19.2 m/s velocity change removed the planetary protection bias and corrected a very small launch injection error. The spacecraft’s maneuver performance was within the spacecraft’s design requirement, and the early navigation result put the estimated encounter position within the 3 sigma execution and orbit determination error ellipse. For the execution of the maneuver, the Mars Surveyor Operations Project relinquished the backup tracking support that was to have been provided by station 43 in order that the DSN could support spacecraft emergencies by NEAR and SOHO.

MCO also executed a science instrument check out sequence on December 23rd. The Pressure Modulator Infrared Radiometer (PMIRR) was powered on and commanded to open its cooler door to the vent position. Telemetry indicated that the instrument is working fine, but the cooler door position is indeterminate at this time. The telemetered switch indication of the door position was indeterminate before the open command and remained that way following the command. Other telemetry suggested that the door motor operated. The PMIRR team is investigating the situation. The Mars Color Imager (MARCI) was also powered on and commanded to acquire eight images. Telemetry indicates that both the MARCI cameras are working well.

MCO is now in a no activity cruise mode with less than full time DSN tracking through the launch period of the Mars Climate Orbiter.

Mars Global Surveyor Mars Global Surveyor (MGS) continues successful aerobraking in its 916th orbit of Mars. Aerobraking is reducing the orbital period by approximately 30 seconds each orbit. The current orbital period is 3 hours 54 minutes.

It is interesting to note that MGS successfully performed an aerobraking trim propulsive maneuver on December 21st just one hour before MCO’s propulsive maneuver. These back to back events demonstrate the multimission operations capabilities of the Mars Surveyor Operation Project.

On December 22nd, MGS’s backup central computer (it is a hot backup, but not in control of the spacecraft) went into contingency mode as the result of a violation of the comparison of its computed sun position and the on-board sun ephemeris. Although contingency mode is the spacecraft’s first level of system fault protection, this situation is not critical since the computer that is in control is not in contingency mode and is managing the spacecraft properly. This condition arose from an event five days earlier when the in-control computer correctly identified two star transients, but the backup computer only identified one, probably due to the 2-second timing difference between the two machines. The attitude error grew during the next five day period to the point where it tripped the sun monitor logic limit on Tuesday. Activities are underway to reestablish normal operations in the backup computer during the coming week. The only risk to the mission is that if there should be a hardware failure in the in-control computer, backup operations would be initiated by the backup computer in contingency mode rather than in the normal operating state (the current sequence would terminate and the spacecraft would fly through the periapsis point in its aerodynamically stable flipped over orientation). Not withstanding this situation, MGS is excellent health.


Friday 18 December 1998

Mars Climate Orbiter

The Mars Climate Orbiter (MCO) is successfully beginning its cruise mission to Mars. On the day (12/12/98) following launch (12/11/98), the spacecraft was reoriented to its nominal cruise orientation putting sun light on the main propulsion engine. Temperatures on various propulsion components increased rapidly, and the flight team decided to return the spacecraft to the initial communications acquisition orientation where it remains today. Several weeks of good communications and solar power generation are available in the current orientation. A study that identifies the strategy for dealing with the transition to another cruise orientation will be complete next Wednesday. On board parameters to configure fault protection properly for the current orientation have been updated. Housekeeping parameters for the early portion of the cruise mission when Deep Space Network tracking time is reduced have been successfully loaded. The spacecraft is in excellent health. Preparations for the first trajectory correction maneuver on Monday (12/21/98) are proceeding very smoothly. A health check of the Mars Color Imager and the opening of the cooler door on the Pressure Modulator Infrared Radiometer instrument are planned for next Wednesday (12/23/98). The burn orientation will be such that telemetry data will be returned in real-time throughout the maneuver.

Mars Global Surveyor

The Mars Global Surveyor spacecraft continues extremely successful aerobraking in its 886th orbit of Mars. The orbit-to-orbit dynamic pressure variability has been has been much lower the past three days. Twelve minutes of margin exist relative to reaching the 2 AM orbital node crossing time target and over 400 km of apoapsis altitude margin relative to the baseline aerobraking plan. In order to converge on the 2 AM target, some of this margin will have to be bled off over the next few weeks. The propulsion fuel tank was successfully repressurized on Thursday (12/17/98) to maintain the proper fuel - oxidizer ratio for future use of the main engine. The spacecraft’s orbit is now with the orbit of Phobos, so no more close encounters will occur.

Mars Polar Lander Pre-launch Support

Final completion of the immediate post launch contingency plans and command files are underway.


Friday 11 December 1998

Mars Global Surveyor Mars Global Surveyor aerobraking operations continue in a very satisfactory manner. The orbital period has been reduced to 4 hours and 23 minutes on MGS’s 845 orbit of Mars. Propulsive maneuvers have been made during the week to not only adjust the dynamic pressure but also to avoid close passage to the satellite Phobos. Tomorrow morning (12/12/98 at 4:40 am PST) the spacecraft will pass within 200 miles (300 km) of the moon Phobos.

It has been determined that the Magnetometer/Electron Reflectometer instrument will be able to remain powered on and acquiring data until at least January 28, 1999, when the spacecraft’s periapsis reaches its southern most point. Aerobraking operations will continue until early February when the orbit will be nearly circular and have a period of two hours.

Mars Climate Orbiter All required prelaunch preparations for operating the Mars Climate Orbiter have been completed. At this writing (8:00 am PST), the count is at L-150 minutes and counting, and all systems are go for launch.


Friday 4 December 1998

Final signoff of the flight operations products for launch support of the Mars Climate Orbiter have been completed and the flight team is ready for the MCO launch on December 10th.

Mars Global Surveyor continues to make excellent progress in its aerobraking activities with the orbital period having been reduced to 4.75 hours. The spacecraft and the aerobraking management team continue their excellent performance without any cause for concern. Approximately 9 minutes of positive margin exists against the baseline aerobraking plan.


Friday 27 November 1998

Mars Global Surveyor aerobraking continues in a satisfactory manner, as does the final operations readiness preparation for the Mars Climate Orbiter launch.


Friday 20 November 1998

All the Mars Surveyor Operations Project (MSOP) operational readiness tests (ORT) for the launch of the Mars Climate Orbiter have been successfully completed with a final launch and initial acquisition test early this past week. The ORTs for the Mars Polar Lander continue in satisfactory manner with a nine day trajectory correction maneuver ORT underway at the present time.

Mars Global Surveyor continues with aerobraking operations that have reduced the orbital period to approximately 5.5 hours. The spacecraft is in excellent health. Earth occultations began once again on November 20th.


Friday 13 November 1998

The Mars Global Surveyor spacecraft continues Phase 2 aerobraking operations in excellent health. Progress continues per plan as 17 minutes of orbit period have been removed over the past 11 drag passes. The 6-orbit running mean is currently 0.268 N/m2 which is above the 0.23 corridor control trigger limit. The project has elected to gain a little orbit period margin and allow the overshoot to occur for a short period. The 2 minute deficit from the baseline plan has now been erased. One corridor control maneuver was executed on the apoapsis of orbit 710.

An operational readiness test was conducted for the Mars Polar Lander launch and initial acquisition activities.


Friday 6 November 1998

Aerobraking by the MGS spacecraft is proceeding smoothly. The spacecraft health is excellent. The atmosphere is stable and, in general, periapsis density levels have been very predictable. After six weeks (90 periapsis passes), the orbital period has been reduced to 7.0 hours and the difference from the planned period reduction path due to the late start for this phase has been completely made up. A periapsis raise maneuver was performed on revolution P686 to reduce the average aerobraking pressure from 0.28 n/m2 to 0.2 n/m2 by increasing the altitude at periapsis by 2 km to 116 km. This level of resistance or lower will be targeted for most of the remainder of the aerobraking phase to follow a "glide-path" reduction rate which will arrive at a two hour period next February just when the orbit plane precession reaches the 2 AM lighting geometry.

On November 2, the TES instrument was turned off to conserve the backup interferometer fringe counting lamp for the mapping phase beginning next March. On November 6, the Project Manager briefed Code S program management on the MGS high gain antenna deployment strategy at the start of the mapping phase. A three week pre-deployment, contingency science period has been created in the new Mission Plan.

A telecom analysis review, held on November 4, confirmed that with minor modification to the Stanford 46 m radio antenna, it will be possible to detect the beacon signals from both MGS and MCO spacecraft relay antennae and from the DS2 landed station uplink carriers during the M’98 relay operation.

Operations personnel participated Mars Polar Lander system data flow tests and the TMOD Launch Readiness Review for the M’98 mission held on Friday, 11/6/98.


Friday 30 October 1998

Mars Global Surveyor continues in excellent health with excellent aerobraking progress. With the orbital period now under 8 hours and close to one-third of the Mars rotation period, better atmospheric density predictions are allowing more aggressive aerobraking. More than half of the timeline deficit caused by the 9 day delay in resuming aerobraking has now been made up, and it is anticipated that orbital period will be on the original baseline guide slope by early December.

MSOP has baselined (for work planning purposes) a period of three weeks at the beginning of the mapping period with the high gain antenna in the stowed (not deployed) position. This is a contingency strategy to assure meeting the minimum mission success criteria. This decision will be revisited following the launches of Mars Climate Orbiter and Mars Polar Lander for final NASA Headquarters concurrence.

The MSOP Readiness Review (Part II) for the Mars Climate Orbiter and Mars Polar Lander was successfully conducted on October 30th.


Friday 23 October 1998

Mars Global Surveyor aerobraking continues with good results. The orbital period has been reduced to 8.5 hours. The spacecraft continues to perform well.

Operational readiness testing continues on schedule for support of the Mars Surveyor ‘98 missions. This week the Mars Surveyor Operations Project participated with an Mars Climate Orbiter launch day rehearsal, and finished the final portion of the Mars Climate Orbiter operational readiness test for the first trajectory correction maneuver.

The dry run (storyboard) session for the second part of the MSOP Readiness Review for the Mars Climate Orbiter, Mars Polar Lander and Stardust launches was successfully conducted.


Friday 16 October 1998

Aerobraking by the MGS spacecraft is proceeding smoothly. After three weeks (45 periapsis passes), the orbital period has been reduced by two hours to 9.4 hours, however, the mission remains an hour behind the planned period reduction path due to the late start for this phase. It was decided to adjust the corridor upwards in pressure to 0.18 n/m2-0.28n/m2 so that a 5 orbit average will produce a 0.235 n/m2 result which will make up an extra 9.5 minutes/week period reduction and arrive on proper glide slope by early December. The atmospheric variability (+/- 0.08) due to longitude changes at 115 km periapsis altitude continues to be a concern. On P615 (October 11) with a peak pressure of 0.32 n/m2, a marginal solar panel vibration frequency alarm caused an immediate 1 km periapsis raise maneuver, slowing aerobraking progress. Another consequence is the time of periapsis prediction error which increased to 300 seconds for the third subsequent orbit prediction following two orbits of low pressure (0.15 n/m2). The error resulted in the use of 20 gms of additional monopropellant. An improved model of the atmospheric variation (three pressure peaks at 120 deg. longitude separation) has subsequently been incorporated into the navigation software for the current periapsis latitude of 60 deg. N.

An Operations Readiness Test for the Mars ‘98 Climate Orbiter Launch and Initial Acquisition was conducted on October 16. This activity followed a five day rehearsal for the first trajectory correction maneuver (TCM1) to be performed ten days after launch. Several procedural revisions did not permit completion of the entire TCM sequence within the allotted time, however the ORT is scheduled to be repeated beginning October 19, 1998.


Friday 9 October 1998

Aerobraking by the MGS spacecraft is proceeding smoothly. After two weeks (32 periapsis passes), the orbital period has been reduced by one hour to 10.3 hours, however, the mission remains an hour behind the planned period reduction path due to the late start for this phase. The 4 orbit average drag force continues to creep higher, now at 0.20 N/m2, with considerable variability (+/- 0.08) due to longitude changes at 115 km periapsis altitude and no corridor control maneuvers have been required. This pressure will be allowed to increase as periapsis naturally lowers until a level of 0.27 n/m2 is reached so as to make up an extra 8 minutes/wk period reduction and arrive on proper glide slope by early December.

Science observations continue to be made near periapsis by the MAG and TES instruments. A successful reactivation of the TES interferometer fringe counting lamp was achieved on the 12th try on October 4 with a signal level of 12 counts. Unfortunately the lamp ceased to function three days later preventing further temperature measurements until the mission mapping phase next March when the backup lamp will be used. Until then only bolometric measurements will be made with the instrument.

Operations Readiness Test rehearsals were conducted on October 6 and 8 for the Mars ‘98 Climate Orbiter Launch, Initial Acquisition and first Trajectory Correction Maneuver. The full ORTs with KSC participation are scheduled to be performed on October 16 and 19, 1998.

Presentations were made by MSOP representatives at the Mars '01 Preliminary Design Review held at Lockheed-Martin Aeronautics October 6-8. The Vandenberg M’01 Launch site was also visited in conjunction with an MSOP support review.


Friday 2 October 1998

The MGS Spacecraft continued Phase 2 aerobraking operations with excellent performance. Periapsis lowering maneuvers (ABMs) of magnitude 0.18 m/s were performed on September 26 and 27 at the apoapses of orbits 580 and 582 which produced the current orbital minimum altitude of 116.0 km. The past 12 orbits have reduced the orbit period by about 40 minutes to 10.93 hr., slightly less than predicted last week. The last four orbits have averaged 0.205 N/m2 drag force with the peak dynamic pressure arriving on orbit 585 at 0.25 N/m2. The average dynamic pressure is in the upper half of the desired corridor for this phase of aerobraking. Discussions have been held to determine if a higher density corridor should be selected for use until the orbit period reduction lost during the 9 days of start delay are replaced. Projections show the current drag force to slowly increase and the periapsis altitude to gradually decrease over the next two weeks.

The structural performance of the -Y solar array yoke continues unchanged from last week. The minimum MOLA laser temperature has reached 9°C and is not expected to drift any lower. Currently, a 75 minute warming maneuver is being utilized on each orbit. The power subsystem showed a maximum battery discharge depth of 12%.

Command files were uplinked on September 26 to power the TES and MAG instruments. The special sequence executed successfully, but the TES interferometer fringe counting lamp, whose performance had degraded to marginally above threshold over the past year, did not come on. By week’s end, after nine attempts consisting of one try every other orbit, it was decided that if the lamp is not activated by next week, only bolometric measurements will be taken during the next three months of aerobraking in order to preserve the backup lamp for mapping.

The MSOP pre-launch operational readiness testing schedule for the Mars Climate Orbiter and the Mars Polar Lander continued with a walkthru of the Launch and Initial Acquisition and Trajectory Correction Maneuver Operations Readiness Test scripts held on September 28 and 29 in preparation for the rehearsal which is currently scheduled to be performed October 15 and 19.

The second M’98 Science Site Readiness Review was held at the UCLA MVACS facility on September 30. Both MARDI/MARCI and MVACS personnel appear to be well equipped to support launch and early cruise operations in part due to their ATLO experience. The PMIRR Review is scheduled to be held on October 9.


Friday 25 September 1998

The Mars Global Surveyor has successfully returned to aerobraking with three propulsive maneuvers to achieve three steps back into the atmosphere. The trajectory is in the desired control corridor with the current aerodynamic pressure at 0.14 N/m2. The periapsis altitude is 121 Km and the orbital period has been reduced to 11.4 hours. The solar array structure seems to be behaving as it did during the last aerobraking period nearly seven months ago and there are no current concerns.


Wednesday 23 September 1998

MGS has returned to Aerobraking:

The MGS spacecraft successfully executed a 11.62 m/s firing of its main engine for 14.8 seconds to take the first of three steps back into the Martian atmosphere. The maneuver at 11:11 PDT appears to be completely nominal. The first drag pass will occur late this afternoon.


Friday 18 September 1998

Telecommunications performance verification testing of Mars Global Surveyor’s backup command path (low gain antenna with transponder 1) was satisfactorily completed early in the past week and plans were established to resuming aerobraking on Thursday, September 17th.

As the spacecraft was preparing for the initial propulsive maneuver that would have been the first step back into the Martian atmosphere, it became apparent that an error in the ground software that generated the spacecraft's sequence, caused an inappropriate positioning of one the spacecraft's solar panels that led to significant discharge of the spacecraft's batteries.

Fault protection routines on-board caught the excess discharge of the batteries, and aborted the maneuver sequence before the turn to the maneuver attitude.

MGS is currently in contingency mode with telecommunications through its low gain antennas at 7.8 bps uplink and 10 bps downlink. The spacecraft attitude control is in the "sun-comm-power" mode, and the spacecraft is safe and stable. The batteries have been recharged.

Over the next days, the flight team will be evaluating several on-board hardware configuration changes that occurred as a secondary result of fault protection triggered by the low charge state of the batteries, and will be developing the sequence to completely restore the spacecraft’s normal configuration.

Resumption of aerobraking is now targeted for Wednesday, September 23rd. These delays are well accommodated within the aerobraking implementation margins.

Excellent support by TMOD - the Deep Space Network around the world, data control - and by the flight members at Lockheed Martin Astronautics in Denver and at JPL in Pasadena are helping us resolve this situation.

The MSOP pre-launch operational readiness testing schedule for the Mars Climate Orbiter and the Mars Polar Lander are being revised as a result of the decision to change out diodes in the MPL hardware.


Tuesday 15 September 1998

After review of the telecom tests that were performed with the MGS spacecraft, the flight team has decided to proceed with aerobraking. Aerobraking will resume with the AB-1 burn at apoapsis A560, about 1100 UTC (or 4 am PDT) on Thursday, September 17th.


Friday 11 September 1998

Mars Global Surveyor is completing its final week in the science phasing orbit period, has celebrated the completion of its first year in orbit about Mars (on Friday, September 11th), and is poised to resume aerobraking to reduce its orbital period from 11.6 to 2 hours. The spacecraft's fuel tank was re-pressurized last Wednesday in preparation for the use of the main bi-propellant engine for the 12 m/s maneuver that will be its first step back into the Martian atmosphere.

A press release today (Friday, September 11th) highlighted the recent images of the largest Martian moon Phobos and the temperature measurements of its surface made by the MGS's Thermal Emission Spectrometer that suggest the surface is composed of very fine dust.

The Mars Orbiter Camera will be turned off on schedule on Sunday, September 13th. The Thermal Emission Spectrometer's mirror will be placed in a safe position, and TES and the Magnetometer/Electron Reflectometer will remain on. Periodic spacecraft reorientations to maintain the Mars Orbiter Laser Altimeter temperature will be continued.


Friday 4 September 1998

The Mars Global Surveyor spacecraft continues to acquire science data with the Mars Orbiter Camera, the Thermal Emission Spectrometer and the Magnetometer/Electron Reflectometer in its next to last week in the science phasing orbit. Data was returned from the third Phobos observation. A press release is anticipated on or about September 10th which will detail the results from the recent Phobos observations. The first of the weekly strategic planning sessions for aerobraking phase 2 was held. The MGS propulsion system will be re-pressurized next Wednesday to ready it for the major maneuvers required to return MGS to the Martian atmosphere.

At the same time that it is flying MGS, the flight team is also preparing for the operational readiness testing that will validate its capabilities to operate the Mars Climate Orbiter and the Mars Polar Lander to be launch later this year.


Friday 28 August 1998

Mars Surveyor Operations conducted the first of a two part review to establish its readiness to support the beginning of Mars Global Surveyor aerobraking phase 2, the readiness of its core infrastructure to support the launches of the Mars Climate Orbiter, the Mars Polar Lander, and ground data system readiness support to the launch of the Discovery mission Stardust. The Review Board found that individual elements of the Project have prepared adequately, however, they cautioned that the sum total of the work to be managed and accomplished far exceeds what has been previously done by such a small operations team. The Project accepts that challenge with careful management of priorities and human resources.

Mars Global Surveyor continues with excellent performance in the final weeks of the science phasing orbit. The next Phobos opportunity is August 31st.


Friday 21 August 1998

Mars Global Surveyor continues to operate superbly in the final weeks of the science phasing orbit period. MGS’s 500th orbit of Mars was celebrated this week. A second observation of the Martian moon Phobos was made with excellent results. Public release of the Phobos data will be made in early September.


Friday 14 August 1998

Mars Global Surveyor continues with routine and very successful science phasing orbit data acquisition activities.


Friday 7 August 1998

Mars Global Surveyor spacecraft operations continue in excellent form. On Friday, August 7th, the spacecraft made its first observation of the Martian satellite, Phobos. Early reports indicate that the satellite was well targeted in the narrow angle field of view of the Mars Orbiter Camera.


Friday 31 July 1998

The Mars Global Surveyor Spacecraft continues in excellent health in its science phasing orbit period. The Mars Orbiter Laser Altimeter instrument (MOLA) will not be used for the rest of this period in order the limit the stress on it caused by repeated on-off cycles. The orbital sequence of events has been altered slightly to provide additional solar heating to compensate for the heat normally generated by the instrument itself, thus maintaining the MOLA’s proper temperature.


Friday 24 July 1998

Mars Global Surveyor spacecraft operations continue without incident in the 11.6 hour science phasing orbit. Science data acquisition and spacecraft performance are excellent.


Friday 17 July 1998

The Mars Global Surveyor continues successfully acquiring science data in the second part of the Science Phasing Orbit period. The spacecraft health remains excellent. Two science instrument calibration activities were completed in the past week: a internal mirror alignment calibration and limb observation for the Thermal Emission Spectrometer, and a set of independent rotations of the spacecraft's solar arrays to complete the calibration of residual spacecraft magnetic fields for the Magnetometer instrument.


Friday 10 July 1998

The Mars Global Surveyor continues in the 11.6 hours science phasing orbit collecting science data with excellent spacecraft performance. Otherwise, there is nothing significant to report.


Friday 3 July 1998

Mars Global Surveyor continues to operate successfully in the second part of the Science Phasing Orbit period. There is nothing significant to report this week.


Friday, 26 June 1998

The Mars Global Surveyor spacecraft continues in good health as it completes its 388th orbit of Mars in an 11.6 hour period elliptical orbit. In this Science Phasing Orbit period, science observations are made during every orbit. At the last turn-on of the Thermal Emission Spectrometer instrument earlier this week, the primary neon reference lamp for the spectrometer did not come on, so the instrument is using only the bolometer (temperature measurement) mode. The backup lamp is being saved for use in important science observations later in the summer and for mapping next year.

The project team is preparing for the operational readiness tests late in July and early August. These tests will demonstrate the team's capabilities to perform aerobraking as the MGS orbital period gets shorter and shorter when aerobraking starts again on September 14th. The current orbital period will be reduced to slightly under 2 hours during the coming fall and early winter. At the same time the MGS orbit period is growing shorter, and aerobraking management intensity will be growing, the Mars Surveyor Operations project team will be taking on the responsibility of managing the flight operations of the Mars Climate Orbiter which launches on December 10th, and the Mars Polar Lander which launches on January 3rd.


Mars Surveyor Operations Project

NASA Jet Propulsion Laboratory

California Institute of Technology

Pasadena, CA 91109