Editing Surveyor 7 (section)

==Science instruments==

===Television===
[[File:20120927 surveyor7-levitating-dust.jpg|thumb|Surveyor 7 observes levitating dust]]
The TV camera consisted of a [[Video camera tube|vidicon]] tube, 25 and 100&nbsp;mm [[focal length]] lenses, shutters, [[Polarizing filter (Photography)|polarizing filter]]s, and iris mounted nearly vertically and surmounted by a mirror that could be adjusted by [[stepping motor]]s to move in both [[azimuth]] and elevations. The polarizing filters served as analyzers for the detection of measurements of the linearly polarized component of light scattered from the lunar surface. The frame by frame coverage of the lunar surface provided a 360 deg azimuth view and an elevation view from approximately +90 deg above the plane normal to the camera A axis to -60 deg below this same plane.{{citation_needed|date=July 2019}}

Both 600 line and 200 line modes of operation were used. The 200 line mode transmitted over an [[omnidirectional antenna]] and scanned one frame each 61.8 seconds.<ref name=":0">{{Cite book |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690027073_1969027073.pdf |title=NASA SP-184 - SURVEYOR Program Results |date=1969 |publisher=NASA |pages=22, 23}}</ref> A complete video transmission of each 200 line picture required 20 seconds and utilized a bandwidth of 1.2&nbsp;kHz.<ref name=":0" /> Most transmissions consisted of 600 line pictures, which were telemetered by a [[directional antenna]]. The frames were scanned each 3.6 seconds.<ref name=":0" /> Each frame required nominally one second to be read from the vidicon and utilized a 220&nbsp;kHz [[Bandwidth (signal processing)|bandwidth]] for transmission.<ref name=":0" /> The [[dynamic range]] and sensitivity of this camera were slightly less than those on the Surveyor 6 camera. Resolution and quality were excellent. The television images were displayed on a slow scan monitor coated with a long persistency [[phosphor]]. The persistency was selected to optimally match the nominal maximum frame rate. One frame of TV identification was received for each incoming TV frame and was displayed in real time<!-- needs disambiguation --> at a rate compatible with that of the incoming image. These data were recorded on a video magnetic [[tape recorder]] and on 70&nbsp;mm film.

Surveyor 7 camera characteristics on 600-line mode were:<ref name=":0" />

* Dynamic range: 11.1:1
* Signal-to-noise ratio (dB): 43.6
* Horizontal relative response at 600 lines (at center of vidicon): 0.20
* Vertical relative response at 600 lines (at center of vidicon): 0.33
* Slope of system transfer characteristic curve: 0.98

The camera transmitted 20,961 pictures during the first lunar day, January 10 to January 22, 1968. From February 12 to February 14, the camera was operated in the 200 line mode because of loss of horizontal sweep in the 600 line mode. During the second lunar day, 45 pictures were transmitted before loss of power caused suspension of camera operation.

On 20 January 1968, it successfully detected two [[Ion laser|argon lasers]] from [[Kitt Peak National Observatory]] in [[Arizona]] and [[Table Mountain Observatory]] in [[Wrightwood, California]].<ref>{{cite web|url=http://www.w7ftt.net/laser2.html|title=Argon Laser as Seen from the Moon}}</ref> This was one of the early tests of [[laser communication in space]].
<gallery heights="140" mode="packed">
File:Surveyor-7-rolling-lunar-terrain.jpg|Rolling lunar terrain northeast of the landing site
File:Surveyor 7 Fig 7-41e2.jpg|Photomosaic of a panorama taken by Surveyor 7 of its landing site.
File:Surveyor 7 Fig 7-41e1.jpg|Panorama of the surface
File:Surveyor 7 Fig 3-43.jpg|An area 350 meters northeast of the spacecraft, showing a large block about 5 meters across and 2 meters high
File:Surveyor 7 Fig 3-57.jpg|Spotted rock 25&nbsp;cm across, about 2 meters from Surveyor 7
File:Surveyor 7 Fig 3-62.jpg|[[Vesicular texture|Vesicular]] fragment about 35&nbsp;cm across, about 7 meters from Surveyor 7
File:Surveyor 7 Fig 3-54.jpg|Broken block 30 to 40&nbsp;cm across, about 2.5 meters from Surveyor 7 camera.
File:Surveyor 7 Fig 3-55.jpg|Spotted fragment about 1.5 meters from Surveyor 7 camera. Bright spots have indistinct boundaries and vary from less than 1&nbsp;mm to about 8&nbsp;mm across.
</gallery>

===Alpha-Scattering Surface Analyzer ===
The alpha-scattering surface analyzer was designed to measure directly the abundances of the major elements of the lunar surface. The instrumentation consisted of an alpha source ([[curium]] 242) collimated to irradiate a 10&nbsp;mm diameter opening in the bottom of the instrument where the sample was located and two parallel but independent charged particle detector systems. One system, containing two sensors, detected the [[energy spectra]] of the [[alpha particle]]s scattered from the lunar surface, and the other, containing four sensors, detected energy spectra of the [[proton]]s produced via reaction (alpha and proton) in the surface material. Each detector assembly was connected to a [[pulse height analyzer]]. A digital electronics package, located in a compartment on the spacecraft, continuously telemetered signals to earth whenever the experiment was operating. The spectra contained quantitative information on all major elements in the samples except for [[hydrogen]], [[helium]], and [[lithium]]. The experiment provided 46 hours of data accumulated from three lunar surface sample measurements. These measurements were of a portion of undisturbed local lunar surface, a lunar rock, and an extensively trenched area of the lunar surface. Data were obtained during the first and second lunar days, January 12 to 23, 1968, and February 13 to 21, 1968.{{citation_needed|date=July 2019}}

The alpha backscattering instrument failed to deploy properly. Mission controllers successfully used the surface soil sampler claw to push the alpha backscattering instrument into the proper position to conduct its experiments.{{citation_needed|date=July 2019}}

===Soil Mechanics Surface Sampler===
The [[soil mechanics]] surface sampler was designed to pick up, dig, scrape, and trench the lunar surface, and transport lunar surface material while being photographed so that the properties of the lunar surface could be determined. The sampler consisted primarily of a scoop with a container, a sharpened blade, and an [[electric motor]] to open and close the container. The flat foot of the scoop incorporated two embedded rectangular horseshoe magnets. The scoop was mounted on a [[pantograph]] arm that could be extended about 1.5 m or retracted close to the spacecraft motor drive. The arm could also be moved from an azimuth of +40° to -72° or be elevated 130&nbsp;mm by motor drives. It could also be dropped onto the lunar surface under force provided by gravity and a spring. The scoop was mounted below the television camera in a position that allowed it to reach the alpha-scattering instrument in its deployed position and redeploy it to another selected location. The instrument performed 16 bearing tests, seven trenching tests, and two impact tests. It also freed the alpha-scattering instrument when it failed to deploy on the lunar surface, shaded this instrument, and moved this instrument for evaluation of other samples. Performance was flawless during 36 hours of operation between January 11 and January 23, 1968. The instrument responded to commands on February 14, 1968, which verified that it had survived the lunar night. The power system, however, was unable to support any operations.{{citation_needed|date=July 2019}}

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