NOTE: Reports to be isuued Weekly after 01-16-98!
Lunar Prospector Mission Status Report #12
January 16, 1998 - 1:00 p.m. EST (10:00 a.m. PST)
The Lunar Prospector spacecraft has been successfully placed into what might be termed its "final mapping orbit," according to the Mission Control Center (MCC) at NASA's Ames Research Center.
The results of yesterday's trim maneuvers (for
details, see Mission Status Report #11, dated Jan 15, 5 p.m. PST)
were such as to place the spacecraft into a 99 km x 100 km
altitude orbit, with an inclination of 90 degrees and a period of
118 minutes. The orbit is (lunar) polar in location, and almost
perfectly circular in nature. It is virtually "right
on" the targeted 100 km (62.5
mile) circular mapping orbit that was planned and anticipated
pre-launch. It is certainly well within the 100 x 20 km (62.5 x
12.5 mile) orbit that is considered to be the most desirable
mapping orbit/altitude.
Of course, the current orbit of the Lunar Prospector spacecraft is subject to degradation with time -- in fact, it will change continuously over time as the gravity anomalies of the Moon pull on the spacecraft, thereby modifying its altitude and its resulting orbit. To address this situation, missions operations personnel will be firing the spacecraft thrusters at periodic intervals to reboost the vehicle to its desired, circular mapping orbit. At the present time, it is believed that the Lunar Prospector spacecraft will remain within the mapping orbit limits (at 100 x 20 km altitude) for about two weeks. Since one of the mission experiments is to learn more about the gravity model of the Moon, the time required between burn maneuvers is uncertain at present. MCC personnel will be gaining knowledge on this aspect of the operation as the Lunar Prospector mission progresses.
The initial estimate of the spin axis pointing after yesterday's reorientation shows it to be about 2.7 degrees from the target, but well within acceptable limits.
The current state of the spacecraft is as follows: the vehicle is on orbit #48; its spin rate is 12.09 rpm; its spin axis attitude is latitude -- 87.1 degrees, longitude -- 218 degrees; the orbit period is 118 minutes. Earth occultations are of 44-minute duration; there are currently no solar eclipses.
Now that the Lunar Prospector spacecraft is in its final mapping orbit, further mission status reports will be issued on a weekly basis, barring any unforeseen events or anomalous situations.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #11
January 15, 1998 - 8:00 p.m. EST (5:00 p.m. PST)
The Lunar Prospector orbit trim maneuvers and spacecraft attitude reorientations scheduled for today were successfully completed this afternoon (p.m. PST), Thurs. Jan 15, 1998, according to Mission Operations Manager Marcie Smith.
Final determination of the orbit will not be available for several hours as the navigation team must collect and verify data for one to two orbits. The spacecraft performed nominally, and it is expected that the vehicle is now within the 100 ± 20 km (62.5 ±12.5 mile) altitude orbit desired for mapping. The attitude is also believed to be within a degree of the desired mapping attitude, with the spin axis near normal to the ecliptic plane.
The timeline for today's events was as follows. At 12:31 p.m. PST, the thruster heaters were activated. This was followed by the firing of the thrusters at 1:44 p.m. PST for a 76.6 second burn to reduce the spacecraft speed by 12.1 meters per second, thereby lowering the aposelene from its initial 153 km (95.6 mile) altitude to something close to the desired 100 km (62.5 mile) altitude. At 2:06 p.m. PST, the thruster heaters were again activated, followed by a 16.4 second burn designed to reduce Lunar Prospector's speed by 2.6 meters per second, thereby raising the vehicle's periselene by about 7 km (4.4 miles) from its original 92 km (57.5 mile) altitude to what is believed to be a new 99 km (61.9 mile) altitude.
At 3:57 p.m. PST, a period of pulsed thruster firing was initiated to reorient the spacecraft to the desired mapping attitude. In all, 139 pulses were fired to precess the spin axis 31.5 degrees. The target attitude is: latitude -- 89 degrees; longitude -- 296 degrees.
The science instruments remain operational and continue collecting excellent data. The precise results of today's maneuvers will be reported in tomorrow's mission status report when the relevant data has been analyzed and verified by mission operations personnel.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #10
January 15, 1998 - 1:00 p.m. EST (10:00 a.m. PST)
As of 10 a.m. PST on Thursday, Jan. 15, 1998, missions operations personnel at the Mission Control Center at NASA's Ames Research Center report that the Lunar Prospector spacecraft continues to operate nominally in its current 2-hour-period orbit.
Now that the spacecraft has been placed in low lunar orbit, radio science data collection has been initiated at the Deep Space Network. These data will be used by the gravity experiment scientist, Alex Konopliv at the Jet Propulsion Laboratory (JPL), in Pasadena, California, to develop a much more detailed gravity map of the Moon.
The spacecraft is currently in orbit # 37, in its lunar orbit insertion attitude, spinning at 12 rpm. All science instruments are on and collecting excellent data. The spacecraft continues to experience occultations (data blackouts) once each orbit, when it goes behind the Moon and communications are lost. Data is continually saved in a 53-minute, rolling-storage unit on the spacecraft Command and Data Handling (C&DH) device. Currently, occultations are 41-minutes long, approaching the maximum expected length of 47 minutes.
Yesterday, Jan. 14 at 11:34 a.m. PST, 10 science configuration commands were sent to the spacecraft to set the gains on the spectrometer instruments.
Later today, mid-afternoon on Jan. 15 PST, the spacecraft orbit will be trimmed to circularize it to the desired 100 km x 20 km mapping orbit. After the orbit trim, the spacecraft will be precessed to its nominal mapping orbit attitude, with the spin axis perpendicular to the ecliptic plane.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #9
January 14, 1998 - 3:00 p.m. EST (12:00 noon PST)
The Lunar Prospector spacecraft continues to operate nominally. The vehicle is in perfect health, and all of the science instruments are operating and collecting data, as planned.
No command activities were scheduled for the past 24 hours as the operations team, which had been working around the clock with most major activities occurring during the night hours, began a transition to move command activities into daylight hours. Overall, operations continue, of course, on a 24-hour basis.
Spacecraft occultations (where the spacecraft passes
behind the Moon as seen from the Earth's ground stations) began
on a "once-an-orbit" basis, starting at 10:54 a.m. PST
yesterday. The first one lasted for about 7 minutes, and they
have subsequently (and already) increased in length to 33.5
minutes. As the Moon goes around the Sun,
occultations will repeat with a 14-day cycle -- 11 days with
occultations and 3 days without them.
Solar eclipses begin in about 8 days and, as they are related to the position of the Sun, they will repeat in half-year cycles. Consequently, missions operations personnel report that we will experience eclipses every orbit for 147 days, then 40 days without eclipses, before repeating the cycle.
The final determination on the spacecraft's current
preliminary mapping orbit shows the vehicle to be in a 92 x 153
km (57.5 x 95.5 mile) orbit. The inclination is 90.1 degrees and
the orbit period is 2 hours (very close to the pre-launch
118-minute predict). This will be trimmed on Thursday afternoon,
Jan. 15 (PST), to put the spacecraft
into a more circular orbit -- within the desired 100±20 km
(62.5±12.5 mile) orbit. Some science configuration commanding is
being performed during the day today, Jan. 14.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #8
January 13, 1998 - 10:00 a.m. EST (7:00 a.m. PST)
The Lunar Prospector spacecraft was successfully placed into a preliminary mapping orbit this morning when the third lunar orbit insertion (LOI) burn was completed, according to missions operations personnel at the NASA Ames Mission Control Center. By firing the two aft axial thrusters on the vehicle for a period of 27 minutes, Lunar Prospector was placed into a nearly circular orbit at an altitude of approximately 100 km (63 miles). All science instruments are collecting good data, and the spacecraft continues to work precisely as planned.
The LOI #3 flyby altitude was 89 km (56 miles), at an inclination of 89.93 degrees. By design, today's LOI burn was deliberately conservative in nature. Initial estimates from the navigation team are that the burn was about 4% low, and that the orbit is still somewhat elliptical at approx. 92 x 160 km (58 x 100 miles). The burn lasted for 27 minutes and used about 23.5 kg (51.7 lbs) of propellant. The spacecraft now has 34 kg (approx. 75 lbs) of propellant remaining to maintain the spacecraft's mapping orbit during its one-year nominal mission (and anticipated extended mission at lower altitude).
After today's LOI burn, the spin rate was trimmed back to 12 rpm to meet science requirements. Tomorrow, Jan. 14, the science instrument gains will be "tweaked" to match the data seen in the mapping orbit. On Thursday, Jan. 15, the orbit will be made more circular in nature, the attitude oriented to the nominal attitude (spin axis perpendicular to the ecliptic plane), and the antenna switched to the medium gain antenna.
Lunar occultations, where the spacecraft passes behind the Moon as seen from the Earth's ground stations, will start later today.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #7
January 12, 1998 - 10:00 a.m. EST (7:00 a.m. PST)
The Mission Control Center at NASA's Ames Research Center reports that the Lunar Prospector spacecraft his now been successfully commanded through 2/3 of the maneuvers required to put it into its final desired mapping orbit configuration approximately 62 miles (100 km) above the lunar surface. That was achieved with this morning's second lunar orbit insertion (LOI) burn. That burn began at 5:58 a.m. EST (2:58 a.m. PST), concluding 27 minutes later at 6:25 a.m. EST (3:25 a.m. PST) with the spacecraft in its scheduled 3.5-hour period orbit. The spacecraft continues to perform precisely as planned.
During LOI #2, the closest approach (periselene) altitude of the spacecraft was approximately 52 miles (83 km), and the furthest distance (aposelene) altitude was an estimated 1170 miles (1870 km). Closest approach during the second LOI burn occured at 6:12 a.m. EST (3:12 a.m. PST). Periapsis is about 30 degrees north and the orbit plane is currently almost perpendicular to the Earth-Moon line, so that if one is looking at the Moon one could see the entire orbit, with periapsis to the upper right and the aposelene about one-half a lunar diameter away from the Moon to the lower left. This means that the spacecraft never gets behind the Moon as seen from Earth and continuous communications can be maintained.
The third and final LOI burn is scheduled for tomorrow morning, beginning at approximately 6:27 a.m. EST (3:27 a.m. PST) and continuing for approximately 30 minutes. Following that burn, mission operations personnel report that they will be experiencing 20-minute occultations during each 2-hour orbit, increasing to 47 minutes within a week. The orbit plane is also perpendicular to the Moon-Sun line, so that the spacecraft will not go behind the Moon into shadow. The first eclipses start about 9 days after LOI burn # 3.
The current spacecraft configuration is: all science instruments on, 3600 bps on the omni antenna, spinning at 12.15 rpm with the spin axis in the LOI burn attitude. To date, the spacecraft has burned 57.95% of its initial fuel load of 138 kg (approx. 304 lbs). Tomorrow's LOI burn is expected to use another 17.4%, leaving 34 kg (approx. 75 lbs). This is sufficient to maintain the spacecraft's mapping orbit under predicted circumstances throughout its primary and extended missions.
A one-hour press conference and status briefing
summarizing activities and accomplishments to date and
highlighting upcoming events and scientific expectations for the
Lunar Prospector mission is scheduled for the main auditorium at
NASA Ames
Research Center on Tuesday morning, Jan. 13, 1998 beginning at 9
a.m. PST (12 noon EST). The briefing will be carried live on NASA
Television.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #6
January 11, 1998 - 10:00 a.m. EST (7:00 a.m. PST)
The Lunar Prospector spacecraft has successfully entered orbit around the Moon, reports Mission Operations Manager Marcie Smith. Following a highly successful first lunar orbit insertion (LOI) burn early this morning, an absolutely critical maneuver for mission success, all indications are that we have a very healthy spacecraft and that everything is right on track for a long and productive science mission, according to Mission Director Alan Binder of the Lunar Research Institute, Gilroy, CA.
At 2:45 a.m. PST (5:45 a.m. EST), the maneuver command to begin the first LOI burn was loaded into the spacecraft register and began timing down. At precisely 3:45 a.m. PST (6:45 a.m. EST), the two thrusters on the underside of the spacecraft were fired for 32.2 minutes continuously to slow the vehicle and put it into lunar orbit. That maneuver was completed at 4:17 a.m. PST (7:17 a.m. EST). Preliminary analysis of the tracking data shows that the spacecraft is in an 11.8-hour period orbit, very close to the target 12-hour orbit.
Today's lunar orbit insertion maneuver was a critical event for the Lunar Prospector spacecraft. If, for whatever reason, the engines could not have been commanded to fire within about 2 hours of the time of closest approach, the mission would have ended in a flyby of the Moon. Now, the spacecraft is safely in a stable orbit. Although second and third LOI burns are scheduled for tomorrow and Tuesday, they are not time critical.
The latest pre-LOI trajectory showed that Lunar Prospector flew by the Moon at an altitude of 71 km (about 45 miles), about 11 km below the original target. The inclination of the orbit was about 89.7 degrees, just below the 89.9 degree target. The time of closest approach was estimated to be 33 seconds earlier than the original target.
The spacecraft is currently spinning at 13.2 rpm, and all science instruments are on and working. Although mission science data collection has not officially begun, the spectrometer scientist was thrilled to see his first lunar data during the time of closest approach.
The initial estimate of the orbit period at 11.8 hours suggests that the orbit will reach an altitude of just over 8,500 km at its furthest distance from the Moon just under six hours after the burn, according to missions operations personnel. A contingency spin trim maneuver scheduled for after the LOI burn was cancelled, as there was very little change in the spin rate during the maneuver and it was not deemed necessary.
The spacecraft performed perfectly throughout the LOI maneuver, even though some minor data outages were encountered. The Deep Space Network (DSN) stations lost lock on the uplink and downlink signal from the spacecraft during the burn as a result of problems experienced in getting the trajectory predictions to the stations before the maneuver. As a result, about 5 minutes of data was lost. Analysis of today's event has ensured that the prediction problem is now well understood; similar outages are not anticipated during the second and third LOI burns tomorrow and Tuesday mornings.
A capture orbit correction maneuver is scheduled for this morning, Jan. 11 at 9:40 a.m. PST (12:40 p.m. EST), if necessary. This will allow correction of the inclination if it was perturbed sufficiently during today's first LOI burn. The next major activity will be initiated at about 3:15 a.m. PST (6:15 a.m. EST) on Monday morning, Jan. 12 when a second 30-minute LOI burn will be fired resulting in a predicted reduction of the orbit period of the spacecraft to only 3.5 hours at the conclusion of LOI 2. The third and final LOI burn is scheduled for early Tuesday morning, Jan. 12, 1998.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #5
January 10, 1998 - 6:00 p.m. EST (3:00 p.m. PST)
The Lunar Prospector spacecraft continues to perform extremely well and is right on schedule, according to Missions Operations Manager Marcie Smith.
Overnight, a possible third trajectory correction maneuver (TCM) was deemed unnecessary and was cancelled. Only 8 science configuration commands were sent to the spacecraft since the last status report.
Missions operations personnel now anticipate that the Lunar Prospector spacecraft will make its closest approach to the Moon within 4 seconds of the planned time, and will fly by at an altitude within 3 km of the target.
The attitude of the spacecraft is currently correct for the first lunar orbit insertion (LOI) firing, and so an overnight reorientation trim manuever was also unnecessary and was cancelled.
The first of the three scheduled lunar orbit insertion (LOI) burns is set for 6:45 a.m. EST (3:45 a.m. PST) on Sunday morning, January 11. Subsequent burns will follow within approximately 24 hours each, early on Monday and Tuesday mornings, depending upon the results of the first LOI burn, its effect upon the spacecraft and the vehicle's resulting orbit.
Status reports on the results of each of the LOI burns will be issued as soon as mission operations personnel can provide verified information. For planning purposes only and subject to change, you are advised that these status reports are currently anticipated to be posted on this website by about 10 a.m. EST (7 a.m. PST) on the mornings of Sunday Jan. 11 and Monday Jan. 12, and at about 12 noon EST (9 a.m. PST) on Tuesday Jan. 13, 1998.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #4
January 9, 1998 - 3:00 a.m. EST (12:00 midnight PST)
At the present time, the Lunar Prospector spacecraft is continuing to perform extremely well according to missions operations personnel Activities today focused on calibration sequences for the science instruments, and analysis of the results of the second trajectory correction maneuver (TCM) executed yesterday. The results are "terrific" according to Marcie Smith, missions operations manager, and Lunar Prospector is now "very close to being right on target." If a third TCM is deemed necessary and is executed tomorrow night, it is anticipated that it will only be a 1 to 2 second burn, given the accuracy of the spacecraft's present course.
Station 24 at Goldstone experienced trouble locking up on the telemetry at the start of its pass today. For about 1.5 hours, the data was noisy and "glitching in and out of lock." After the subcarrier frequency was adjusted by a modest amount, the station was able to lock up and stay in solid lock. A telecon tomorrow with the Deep Space Network (DSN) engineer will clarify procedures designed to prevent this situation in the future. Due to the rolling storage of data, 53 minutes of this data will be corrected by data processing.
Commanding today consisted of science configuration and calibration commanding, and the execution of the reorientation maneuver placing the spacecraft into its attitude for Lunar Orbit Insertion (LOI).
At this time, the spacecraft is ready for LOI -- it is at the right attitude and spin period, and on course. A very small velocity trim may be executed tomorrow night. The spacecraft has all 5 instruments up and operating and collecting good data. To date, 250 commands have been sent to the spacecraft and all have executed normally.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #3
January 8, 1998 - 12:00 noon EST (9:00 a.m. PST)
Lunar Prospector mission operations personnel report the successful completion of activities on day 2 of the mission timeline. Excellent support from the Deep Space Network has ensured no significant outages in telemetry or command uplink. The monitoring of engineering and science data was the primary activity during this first full-day of spacecraft operation. All systems appear normal.
Between 1:09 a.m. and 2:44 a.m. (EST), the Electron Reflectometer, Neutron Spectrometer, and Gamma Ray Spectrometer instruments were commanded to high voltage. There were no anomalies and all instruments are currently providing good data. The current focus for the instruments is to collect calibration data enroute to the moon.
The second trajectory correction maneuver (TCM) was performed between 3:25 and 3:40 a.m. (EST). It was relatively small, only 8.4 m/s, and the navigation team was busy verifying the results during the overnight session. A third TCM has been scheduled for Friday night/Saturday morning to trim out any final errors.
It had been scheduled that the spacecraft would be placed into its attitude for lunar orbit insertion (LOI) burn after the TCM tonight, but that has been postponed until tomorrow afternoon. This will allow the dynamics engineer to get an update on the initial attitude, which changed slightly due to the TCM.
The current configuration of the spacecraft is as follows: it is spinning at 12.685 rpm, at cruise attitude, and all instruments are on. Data is currently being transmitted to the ground tracking station at 3600 bps (science format) on the omni antenna.
Activities for the next 24 hours include a command session beginning about 8 p.m. EST (Jan. 8) to command two of the instruments which may need gain changes, and to reorient the spacecraft to the LOI attitude.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #2
January 7, 1998 - 09:30 a.m. EST (6:30 a.m. PST)
Following its spectacular launch at 9:28:44pm EST (6:28:44 PST) on January 6 from the new Spaceport Florida commercial pad at Cape Canaveral, FL, the Lunar Prospector spacecraft is performing extremely well, according to operations personnel in the Mission Control Center (MCC) at Ames Research Center in Moffett Field, CA.
As of 7:30am EST, the spacecraft's science booms have been completely and successfully deployed, and all science instruments--including the Magnetometer (MAG), the Electron Reflectometer (ER), the Neutron Spectrometer (NS), the Gamma Ray Spectrometer (GRS), and the Alpha Particle Spectrometer (APS)--have been turned on. The first trajectory correction maneuver (TCM) has been performed with preliminary results looking very good, according to Missions Operations Manager Marcie Smith.
The spacecraft is currently spinning at 11.2 rpm, as planned, at the nominal cruise attitude. Mission control reported some anticipated problems with poor quality following initial data acquisition. This resulted from the geometry of the link between the spacecraft and the ground station--with the body of the vehicle itself partially blocking communication. Consequently, mission operations personnel delayed the scheduled spacecraft orientation until improved data quality could be achieved.
Since the deployment sequence for the spacecraft's science booms was delayed, the original reorientation of the spacecraft was modified to put the vehicle in a more favorable thermal condition for boom deployment. The spacecraft was oriented to the nominal cruise attitude following science configuration mission operations personnel report.
The spacecraft's science instruments will be turned to high voltage today, following a 'degassing' period, and a second vehicle TCM will be performed, if required.
David Morse
Ames Research Center
Moffett Field, CA 94035
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Lunar Prospector Mission Status Report #1
January 7, 1998 - 12:30 a.m. EST (9:30 p.m. PST, Jan. 6)
NASA's Discovery program of low-cost, science-focused space exploration missions got a major boost Tuesday evening with the successful launch of Lunar Prospector. At the time, all spacecraft systems are operational and Lunar Prospector is on its way to the moon.
The compact spacecraft, atop a Lockheed Martin Athena II launch vehicle, roared off Spaceport Florida's pad 46 at the new, commercial launch complex at Cape Canaveral, FL, on schedule at 9:28:44 p.m EST (6:28:44 p.m. PST), less than one second into the opening of today's launch window.
The launch vehicle's three stages worked as planned, rocketing the craft to an altitude of 62,500 feet after 88 seconds at stage 1 burnout. All additional milestones were achieved on schedule during the remainder of the ascent phase, culminating in attainment of a successful "parking orbit" around the Earth at an altitude of 125 statute miles.
After completing almost three-quarters of a revolution around the Earth, the vehicle's Trans Lunar Injection (TLI) stage completed a successful 64 second burn, blasting the small spacecraft out of Earth orbit and setting the spin stabilized vehicle on its 105 hour "coasting" mission to the Moon.
Telemetry and tracking data were acquired on schedule at launch (T) plus 6 minutes and 20 seconds at Antigua, at T + 20 minutes and 23 seconds at Ascension, and at T + 51 minutes and 40 seconds at Australia. Deep Space Network data acquisition at Goldstone, CA occurred at T + 1 hour and 18 minutes, as scheduled. Payload separation from the third stage of the launch vehicle was successfully completed at T + 55 minutes and 15 seconds. Spacecraft turn-on was accomplished 56 minutes and 30 seconds after launch.
Lunar Prospector will conduct a one-year primary mission, mapping the surface composition and internal structure, volatile activity, and magnetic and gravity fields of the Moon from an altitude of approximately 63 miles. Additional mapping at altitudes as low as 6 miles above the lunar surface is planned over the following 6 months. Lunar Prospector is expected to provide definitive evidence of the presence or absence of water ice in the shaded lunar polar regions.
The Lunar Prospector spacecraft was built for NASA by Lockheed Martin Missiles and Space, Sunnyvale, CA. The Athena II launch vehicle was provided by Lockheed Martin Astronautics, Denver, CO. Science instruments and other important contributions were provided by the Los Alamos National Laboratory, the U.C. Berkeley Space Science Laboratory, the University of Arizona, Tucson, AZ, and NASA's Goddard Space Flight Center, Greenbelt, MD and Jet Propulsion Laboratory, Pasadena, CA. Alan Binder of the Lunar Research Institute, Gilroy, CA is the Principal Investigator. The Lunar Prospector mission manager is Scott Hubbard of NASA's Ames Research Center, Moffett Field, CA.
David Morse
Ames Research Center
Moffett Field, CA 94035
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