PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "20090626, L. Gaddis - Initial Version 20101001, C. Isbell - Post review" RECORD_TYPE = STREAM OBJECT = MISSION MISSION_NAME = "LUNAR ORBITER III" OBJECT = MISSION_HOST INSTRUMENT_HOST_ID = "LO3" OBJECT = MISSION_TARGET TARGET_NAME = MOON END_OBJECT = MISSION_TARGET END_OBJECT = MISSION_HOST OBJECT = MISSION_INFORMATION MISSION_START_DATE = 1967-02-05 MISSION_STOP_DATE = 1967-10-09 MISSION_ALIAS_NAME = "LO3" MISSION_OBJECTIVES_SUMMARY = "As described in MISSION_DESC below." MISSION_DESC = " THE LUNAR ORBITER III MISSION ============================= Overview -------- Much of the information in this document was abstracted from the Lunar Orbiter mission pages of the National Space Science Data Center (NSSDC) Web site (http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1967-008A). See references cited for more detail. The Lunar Orbiter III mission obtained photographs of areas of the lunar surface for confirmation of safe landing sites for the Surveyor and Apollo missions [e.g., Boeing Company, 1967, 1968a, b; Hansen, 1970; Kosofsky and El-Baz, 1970; Bowker and Hughes, 1971; Byers, 1977]. It also collected selenodetic, radiation intensity, and micrometeoroid impact data. The primary objective of Lunar Orbiter III was to re-photograph the most promising lunar landing sites photographed by Lunar Orbiter I and II and to help determine landing vehicle configuration and verify vehicle design. The Lunar Orbiter III spacecraft was launched from Cape Kennedy on 1967-02-05 at 01:17 GMT by an Atlas-Agena launch vehicle [Zwiegbaum, 1966]. On 1967-02-08 at 21:54 UT, the spacecraft was placed in a cislunar trajectory and injected into an elliptical near-equatorial lunar orbit. The orbit was 210.2 km x 1801.9 km with an inclination of 20.9 degrees and a period of 3 hours 25 minutes. After four days (25 orbits) of tracking the orbit was changed to 55 km x 1847 km. The spacecraft acquired photographs between 1967-02-15 and 1967-02-23, and readout occurred through 1967-03-02. The film advance mechanism showed erratic behavior during this period resulting in a decision to begin readout of the frames earlier than planned. The frames were read out successfully until 4 March when the film advance motor burned out, leaving about 25% of the frames on the takeup reel, unable to be read. The spacecraft was used for tracking purposes until it impacted the lunar surface on command at 14.3 degrees N latitude, 92.7 degrees W longitude (selenographic coordinates) on 1967-10-09. Objectives ---------- The primary objective of Lunar Orbiter III, the final 'site certification' mission of the Lunar Orbiter series, was to continue the Lunar Orbiter I and Lunar Orbiter II task of photographing promising areas of the lunar surface to determine their adequacy as Apollo and/or Surveyor landing sites. The spacecraft acquired photographic data from 1967-02-15 and 1967-02-23, with 211 exposures taken of 13 primary Apollo zones sites during 54 successive orbits. Mission III added to the far side coverage from Lunar Orbiter II and zoomed in on more oblique shots for scientific purposes. A total of 157 medium resolution and 173 high resolution frames were returned [e.g., Beeler and Michlovitz, 1969; Boeing Company, 1968a, b; Hansen, 1970; Anderson and Miller, 1971]. The frames were of excellent quality with resolution down to 1 meter. Included was a frame of the Surveyor 1 landing site, permitting identification of the location of the spacecraft on the surface. The second objective of Lunar Orbiter III was to collect selenodetic, radiation intensity, and micrometeoroid impact data. Accurate data were acquired from these experiments throughout the mission. The radiation dosimetry measurement system functioned normally and provided data on the Earth's trapped radiation belts and on the radiation environment encountered by the spacecraft in transit to and near the Moon. No micrometeoroid hits were recorded during Mission III, although one detector was punctured prior to launch. MISSION OPERATIONAL PHASES ========================== Mission phases were defined for significant spacecraft activity periods. For all five Lunar Orbiter missions, phases included at least the launch, trajectory, orbit insertion, orbital operations (primarily photographic imaging), and surface impact. The Lunar Orbiter III spacecraft was a three-axis stabilized vehicle with three- axis stabilization and attitude control provided by four one-lb nitrogen gas jets. The attitude reference for yaw and pitch was provided by a Sun sensor in the equipment mounting plate so that the solar panels normally faced the Sun. The roll axis reference was provided by an electro-optical sensor that tracked the star Canopus. Gyros in the inertial reference unit maintained attitude of the spacecraft with respect to inertial and celestial references whenever the Sun or Canopus was hidden to within +0.2 and 2.0 degrees. Attitude control was maintained with the spacecraft pitched from 15 to 45 degrees away from the Sun for approximately 56% of the Lunar Orbiter III mission. Launch ------ The Lunar Orbiter III spacecraft was launched from Cape Canaveral, Florida on 1967-02-05 01:17 GMT on an azimuth of 80.8 degrees [e.g., Boeing Company, 1967]. Launch was achieved using an Atlas-Agena D vehicle [Zwiegbaum, 1966]. Following separation from the Atlas, the Agena engine put the spacecraft into Earth orbit. The first- and second-stage boosters performed as programmed. The spacecraft's Earth Parking Orbit Coast time was 6 minutes, 45.0 seconds. Tracking and telemetry for the launch were provided by the Air Force Eastern Test Range (AFETR) Deep Space Network (DSN) and Manned Space Flight Network (MSFN) as elements of the Tracking and Data System (TDS). Spacecraft Id : 67-008A Target Name : MOON Mission Phase Start Time : 1967-02-05 Mission Phase Stop Time : 1967-02-05 Spacecraft Operations Type : ORBITER Cislunar Trajectory ------------------- Lunar Orbiter III was injected into the cislunar trajectory at the end of the Agena second burn, approximately 20 minutes after liftoff. Separation of the Agena followed approximately 3 minutes later. The cislunar orbit injection point on 1967-02-05 at 01:36 GMT was on an azimuth 81.6o near the western edge of Africa in the Atlantic Ocean. DSN stations tracked the spacecraft until a star map maneuver was initiated 10 hours and 35 minutes after liftoff and Canopus was located successfully. The midcourse maneuver was executed at 1967-02-06 15:00 GMT, approximately 37.5 hours after cislunar injection. Spacecraft Id : 67-008A Target Name : MOON Mission Phase Start Time : 1967-02-05 Mission Phase Stop Time : 1967-02-06 Spacecraft Operations Type : ORBITER Lunar Orbit Insertion --------------------- The spacecraft was injected into an elliptical near-equatorial lunar orbit on 1967-02-08 at 21:54 UT, 92 hours and 37 minutes after liftoff. The velocity control rocket engine operated for 542.5 seconds, producing a velocity change of 704.3 meters per second. The spacecraft achieved an initial orbit with an apolune of 1802.1 km, a perilune of 200.2 km, and an orbital inclination of 20.94 degrees to the lunar equator and a period of 205 minutes. The orbit was established with perilune near the equator on the Moon's eastern limb. Spacecraft Id : 67-008A Target Name : MOON Mission Phase Start Time : 1967-02-08 Mission Phase Stop Time : 1967-02-12 Spacecraft Operations Type : ORBITER Orbit Transfer and Lunar Imaging -------------------------------- The transfer from initial to photo ellipse orbit was executed on 1967-02-12 at 18:13 GMT, during Orbit 26, 185 hours after launch. The new orbit had an apolune of 1847.35 km, a perilune of 54.85 km, and an inclination of 20.94 degrees with a period of 208.56 minutes. The placement of the orbital plane had to be such that, when the Moon's rotation brought the selected sites beneath the perilune, the site would be properly illuminated for photography (with Sun 10o to 30 o above the local horizon). In general, the sites on the Moon's near side were photographed with sunrise illumination and the far side areas with sunset illumination. The spacecraft made a total of 1843 orbits over 243 days. The spacecraft acquired photographic data from 1967-02-15, during Orbit 44, to 1967-02-23, during Orbit 97. Photography was completed about the time of the full Moon. Readout occurred through 1967-03-02. During the photo period, 211 photos were taken of 51 sites. Bimat was cut during Orbit 98 and 36.48 photos were received during priority readout. Final readout was initiated 3 hours after Bimat cut and progressed normally through Orbit 148. The film advance mechanism showed erratic behavior during this period resulting in a decision to begin readout of the frames earlier than planned. The frames were read out successfully until 1967-03-04 when the film advance motor burned out, leaving about 25% of the frames on the take-up reel, unable to be read. Spacecraft Id : 67-008A Target Name : MOON Mission Phase Start Time : 1967-02-12 Mission Phase Stop Time : 1967-03-04 Spacecraft Operations Type : ORBITER Surface Impact -------------- Lunar Orbiter III was commanded to impact the Moon at 14.3 degrees N latitude, 92.7 degrees W longitude (selenographic coordinates) on 1967-10-09 [e.g., Hansen, 1970]. Spacecraft Id : 67-008A Target Name : MOON Mission Phase Start Time : 1967-02-12 Mission Phase Stop Time : 1967-10-09 Spacecraft Operations Type : ORBITER LUNAR ORBIT SUMMARY =================== Mission III photography was conducted as planned except for minor shifts in some photo site locations, the addition of a fourth pass over the Surveyor 1 landing site, and the cancellation of the last secondary site [e.g., Boeing Company, 1967]. To provide access to both Mission I and II primary sites with acceptable lighting conditions, the orbit inclination of this mission was increased to 21ø. The orbit determination program (ODPL) for Mission III was changed slightly from the previous two missions. The deboost maneuver on 1967-02-08 injected the spacecraft into the initial lunar orbit. Orbit determination used for the design of the deboost maneuver was based on 37 hours of tracking data. The design philosophy was to guide the spacecraft from its approach hyperbola into an ellipse such that the ellipse inclination and apolune altitude, as well as other ellipse parameters, resulted in the preflight nominal values. The attitude maneuver was chosen to maintain Sun lock as long as possible, keep the DS vector from passing through any antenna null regions, and minimize the total rotation angle. The deboost maneuver was completed 10 minutes before engine ignition. Orbit determinations during the four days from deboost to transfer consisted of routine updating of the spacecraft vector and support of the orbit transfer maneuver design. The transfer from initial to photo ellipse was executed on 1967-02-12 during Orbit 26 of the initial ellipse. The orbit determination for the transfer calculation (OD 4234) used 14.3 hours of two-way lock Doppler tracking data. The transfer maneuver was designed by targeting to the three parameters: (1) perilune radius; (2) latitude of perilune; and (3) longitude of the ascending node. The targeting parameters were specified at the first perilune following the transfer maneuver. The desired perilune radius (1792.87 km) was selected to satisfy the minimum perilune altitude constraint of 48 km approximately midway through the photo activity. The desired perilune latitude (0.596 degree) centers on the perilune trace properly with respect to the photo sites. The desired longitude of the ascending node (257.93 degrees) optimizes the lighting angle of the photo targets. By choosing the transfer true anomaly of 206 degrees, the apolune radius was held at the nominal value and orbit inclination changed only slightly. The time of the maneuver satisfied the tracking time constraint and the required velocity change (50.73 m/sec) was well below the budgeted (302.0 m/sec). The attitude maneuvers required to perform this transfer were 51.74 degrees sunline roll and 19.86 degrees pitch. Selection of this attitude maneuver sequence was based on maintaining Sun lock as long as possible and compliance with antenna constraints with a minimum of angular rotation. Immediately after monitoring the transfer maneuver Doppler shift, tracking data were logged and edited and the first orbit determination was made after the burn. Between 18 and 19 orbit revolutions took place from transfer to the first photo. All photo activity occurred during the photo ellipse. There were 156 frames exposed for primary photo sites and 55 frames exposed for secondary sites. The A total of 50 orbit determinates were made before Bimat cut; 30 were used to support command conferences for each photo event. The altitude range for photographs was 44 to 1460 km. For orbit determination, a basic set of lunar harmonic coefficients (LRC 11/11/66 set) was tailored to the particular gravitational field being experienced by solving for eight of the higher order coefficients (C32, C42, C33, C43, S32, S42, S33, S43). This procedure produced good fits to the tracking data, no divergence problems were encountered, and the resultant orbital elements were consistent. The data arc used was four orbits in length. Perilune data was used in the fit and Doppler data oscillations near perilune observed previously in Missions 1 and 2 were again present. No ranging data were included in the fits because none was taken after photography started. Orbit determinations were done for both the preliminary and final command conferences. Although tracking data obtained during photo readout were two to ten times noisier and had more frequent blunder points caused by photo readout interference, they were nevertheless usable data. Data were sampled at 20-second intervals during these periods-instead of the normal 60-second rate-and then compressed to 60-second intervals by the editing programs. This procedure resulted in a smoother data stream for orbit determination use. OBSERVATIONAL STRATEGY AND RESULTS ================================== During Lunar Orbiter Missions I and II, all of the primary sites being considered for future landing sites were photographed by using standard techniques [e.g., Hansen, 1970]. For example, coverage was obtained by taking sequences of 4, 8, or 16 vertical photographs during one or more passes of the spacecraft over the site. This procedure provided stereoscopic medium-resolution and high-resolution coverage useful primarily for site characterization and photometric analysis. However, a successful experiment conducted during Lunar Orbiter II determined that even better stereoscopic coverage ('convergent stereo photography') could be achieved with the high resolution camera by photographing the same area during two consecutive passes with the camera axes tilted during one of the passes. Lunar Orbiter III was then designated a site-certification mission and it was designed to provide additional coverage of the most promising candidate Apollo landing sites photographed during Lunar Orbiter I and II [e.g., Hansen, 1970; Bowker and Hughes, 1971]. The 12 primary sites photographed during Lunar Orbiter III included 5 areas previously photographed during Lunar Orbiter I, 5 areas previously photographed during Lunar Orbiter II, and 2 proposed Surveyor landing sites which had been selected on the basis of Earth- based photography. To photograph all these areas under favorable lighting conditions, the inclination of the orbit to the lunar equator was increased from the 12-degree value used for Lunar Orbiter I and II to a value of 21 degrees. More diverse photographic techniques were used during Lunar Orbiter III to obtain vertical, oblique, and converging coverage. Although the late problem with the film advance motor caused a failure to read out many of the Lunar Orbiter III photographs, the mission nevertheless provided the Apollo program with sufficient information to allow the following Lunar Orbiter IV and V missions to address more expanded scientific objectives." END_OBJECT = MISSION_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ANDERSON&MILLER1971" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BEELER&MICHLOVITZ1969" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BOEINGCO1967" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BOEINGCO1968A" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BOEINGCO1968B" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BOWKER&HUGHES1971" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BYERS1977" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "HANSEN1970" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "KOSOFSKY&ELBAZ1970" END_OBJECT = MISSION_REFERENCE_INFORMATION OBJECT = MISSION_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ZWEIGBAUM1966" END_OBJECT = MISSION_REFERENCE_INFORMATION END_OBJECT = MISSION END