A Reproduced Copy OF Reproduced for NASA by the NASA Scientific and Technical Information Facility FFNo 672 Aug 65 g rln STAR (Items announcedin STAR ore modeovo;Ioble to the r UNCEMENT AND DISTRIBUTION i in CSTAR (Items announced in CSTAR may be secur;ty cl Public release confirmed 5/23/16 _ould be usedonly for puq_osesof the U. S. Governmentand itl ,'-,',._-._f, • , --..: ° 1967 i (CODE) (NASA CR OR TNIX OR AD NUMBER) (CATEGORy) JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY PASADENA, CALIFORNIA I I I Project Document 125 I I SURVEYOR III i PRELIMINARY SCIENCE RESULTS i PD 125 May 15, 1967 I l Prepared by The Surveyor Experimenter Teams and Working Groups I National Aeronautics and Space Administration I and I _et Propulsion Laboratory, California Institute of Technology IO I I JET PROPULSION LABORATORY i CALIFORNIA INSTITUTE OF TECHNOLOGY PASADENA, CALIFORNIA I I I I I I I '1 Project Document 125 I Copyright _ 1967 _Jet Propulsion Laboratory California Institute of Technology I Prepared Under Contract No. NAS 7-100 National Aeronautics & Spoce Administration ! ll I I I i I g I I JPL Project Document 125 I CONTENTS I I. Introduction and Summary T. Vrebalovich, L. D. Jaffe, and S. E. Dwornik ........... I-1 to I-5 Scientific Personnel ................................ II-1 to II-3 i TT. Lunar Surface Electrical Properties W. E. Brown, R. A. Dibos, G. B. Gibson, I: _- D. O. Muhleman, W. H. Peake, and V. T. Peohls ........ III-1 to IH-Z lY v Lunar Surface Mechanical Properties E. M. Christensen, S. A. Batterson, H. E. Benson, I K. Choate, L. D. Jaffe, 1%. H. Jones, H. Y. Ko, P_. L. Spencer, F. B. Sperling, and G. H. Sutton ......... IV-1 to IV-5Z ljv Soil Mechanics Surface Sampler: Lunar Surface Tests and Results K R. F. Scott, F. I. Roberson, and M. C. Clary ............ V-1 to V-4Z Jvi. Lunar Temperatures and Thermal Characteristics J. W. Lucas, ft. E. Conel, W. A. Hagemeyer, C. B. Jones, J. M. Saari, and J. T. Wang ............. VI-1 to VI-38 I/vii Television Observations From Surveyor III E. M. Shoemaker, R. M. Batson, H. E. Holt, E. C. Morris, J. J. Rennilson, and E. A. Whitaker ...... VII-1 to VII-86 _/ VTTT. Lunar Theory and Processes D. Gault, R. Collins, T. Gold, J. Green, G. P. Kuiper, H. Masursky, J. O'Keefe, I R. Phinney, and E. M. Shoemaker ................ VIII-1 to VIII-Z5 I I I - 0.o 111 ! JPL Project Document 125 I I I. INTRODUCTION AND SUMMARY T. Vrebalovich, L. D. Jaffe, and S. E. Dwornik I Surveyor III soft-landed on the Moon at 00:04 GMT on April 20, 1967. Data I obtained have significantly increased our knowledge of the Moon. The Surveyor III spacecraft was similar to Surveyor I (Refs. I-1 and I-2); the only major change in scientific instrumentation was the addition of a soil mechanics surface sampler. This device replaced an approach television camera, which was carried but not used on Surveyor I. The soil mechanics surface sampler I is essentially the instrument described previously by Scott (Ref. I-3), but without strain gages, accelerometer, or position potentiometers. It consists primarily of l a scoop about 12 cm long and 5 cm wide, mounted on a pantograph arm that can be extended about 1.5 m, or retracted close to the spacecraft, by a motor drive. The I arm can also be moved in azimuth and elevation by motor drives, or dropped onto the lunar surface, under force provided by gravity and a spring. A door on the_coop can be opened and closed by a motor. The soil mechanics surface sampler can I manipulate the lunar surface material in a number of ways, and the results can be observed by the Surveyor television camera. Figure V-2 of the following section by I Scott, Roberson, and Clary shows the spacecraft configuration with this instrument aboard. I A minor difference between Surveyors I and III was that Surveyor III carried two auxiliary mirrors, attached to the spaceframe, to permit better survey of I selected areas below the spacecraft in its landed position, where interaction between lunar surface and spacecraft might occur. Some small modifications were made in le the television survey camera itself. Television was treated as a scientific experi- ment on Surveyor III. The spacecraft was launched from Cape Kennedy, Florida, at 07:05:01 GMT I on April 17, 1967. An Atlas/Centaur launch vehicle placed the Surveyor into a parking orbit at 165-kin altitude and, after a coast of 22 rain, 9 sec,injected it into a I trajectory intersecting the Moon. The spacecraft mass at injectionwas 1040 kg; after final touchdown, 302 kg. A midcourse maneuver was performed on April 18. I The center of the aiming ellipse chosen for this maneuver was selenographic latitude 2.92°S, longitude 23.25°W. Surveyor llI landed at 2.94°S, 23.34°W, within 2.8 km i of the aiming point. | I-1 JPL Project Document 125 II The landing site is the southeast portion of Oceanus Procellarum, about 370 km south of the crater Copernicus. The spacecraft rests in a subdued, rounded crater I about 200 m in diameter and is inclined 12 to 15 ° to the horizontal on the eastern slope of the crater. The crater was identified, and the location of Surveyor III within it was determined by comparing features visible from the Surveyor with those I found in high-resolution Lunar Orbiter III photographs. As in the Surveyor I landing, strain gages recorded the loads in each shock I absorber during the landing events. Interpretation of these records and other data received from the spacecraft showed that, because the vernier engines did not shut I wn at the planned height of 4 m above the surface prior to the first touchdown, three separate touchdowns on the lunar surface took place. Since the spacecraft had I a lateral velocity of about 1 m/sec, the distance between the first and second touch- down events was about 20 m, and between the second and third impact about 11 m. I A final translational movement of about 30 cm occurred following the third touchdown. The vernier engines, which had maintained a stable spacecraft during all of the landing events, shut down prior to the third touchdown. O The marks of the footpads on the lunar surface in the second touchdown, though not in the first, have been identified in the post-landing pictures. Their position il correlates with the interpretation of the landing dynamics. There may have been a small amount of soil erosion by the vernier engines during the second touchdown. I Lunar r_aterial disturbed by the vernier engines during the unique landing may have coated part of the mirror of the television camera or abraded it, causing I the glare evidenced in portions of many television pictures. Temperature measure- ments indicate no dust layer on Surveyor's thermal compartments. The television camera could not view the lunar surface outside the crater I within which Surveyor III landed, but the sloping walls of the crater allowed it to ew nearby features more clearly than would have been possible on a flat terrain. I The spacecraft took 6315 pictures from April 20 to May 3, 1967. Data on the mechanical properties of the lunar surface material were I obtained from examination of the depth of the footpad imprints, strain gage records, and computer simulation of the landing, as well as by the soil mechanics surface I sampler. The surface sampler made 8 bearing tests and 14 impact tests on the lunar surface, and dug four trenches; it picked up three objects on the lunar sur- face. One o[ these, a small rock, was gripped in the surface sampler scoop, which II exerted a pressure of at least 107 dynes/cm 2 (10 z psi) on the rock without apparently crushing or breaking it. I I-2 il JPL Project Document 125 In general, the character and properties of the lunar surface at the Surveyor III site seem very similar to those at the Surveyor I site. The position inside or outside a crater or in different mare locations does not seem to make a gross difference in surface characteristics. This similarity includes the mechanical properties of the soil. The static bearing strength, on bearing widths of Z to Z0 cm, is about Z x 105 to 5 x 105 dynes/cm z (3 to 8 psi), the cohesion 103 to 104 dynes/cm z -Z -1 (10 to 10 psi), and the angle of internal friction roughly 35 ° The elastic rigidity modulus of the top Z0 cm or so, as indicated by the frequency of vibration of the spacecraft on the surface, is about 5 x 106 dynes/cm z. This is much lower than Otis Accordingtypical forto presentloose sand,measurements,and may representthe penetrationfine, looselyof the packedfootpads particles.into the surface material during touchdown did not exceed 5 cm. I The distribution of craters and rock-like features near Surveyor III is not much different than that observed by Surveyor I. Large blocks were more frequent around I some of the 10- to 15-m-diameter craters near Surveyor III. Blocks up to 4 m long were visible from the spacecraft; some of these were angular or flat, others were more rounded. Sizes of individual visible particles extended down to the 0.5-ram I limit of camera resolution; over 85% of the exposed surface consisted of unresolved finer material., The surface retained a clear imprint of the bottom of a foot%'pad, which had ridges of the order of 60 microns high.