Editing Surveyor 6

{{Short description|American lunar lander}}
{{Use mdy dates|date=May 2020|cs1-dates=y}}
{{Infobox spaceflight
| name               = Surveyor 6
| image              = Surveyor NASA lunar lander.jpg
| image_caption      = Surveyor model on Earth
| mission_type       = Lunar [[Lander (spacecraft)|lander]]
| operator           = [[NASA]]
| website            = 
| COSPAR_ID          = 1967-112A
| SATCAT             = 03031
| mission_duration   = 37 days (launch to last contact)
| spacecraft_type    = 
| manufacturer       = [[Hughes Aircraft]]
| launch_mass        = {{convert|1,008.3|kg|lb}}<ref name="Surveyor 6">{{cite web|url=https://solarsystem.nasa.gov/missions/surveyor-6/in-depth/ |title=Surveyor 6 |date=December 27, 2017 |publisher=NASA's Solar System Exploration website |access-date=December 2, 2022}}</ref>
| landing_mass       = {{convert|299.6|kg|lb}} after landing
| power              = <!-- [[watt]]s -->
| launch_date        = {{start-date|November 7, 1967, 07:39:01|timezone=yes}}&nbsp;UTC <ref name="Surveyor 6"></ref>
| launch_rocket      = [[Atlas-Centaur|Atlas SLV-3C Centaur-D]] AC-14
| launch_site        = [[Cape Canaveral Air Force Station|Cape Canaveral]] [[Cape Canaveral Air Force Station Space Launch Complex 36|LC-36B]]
| launch_contractor  = 
| last_contact       = {{end-date|December 14, 1967}}; last useful data November 24
| orbit_epoch        = 
| orbit_reference    = <!--transfer orbit-->
| orbit_periapsis    = 
| orbit_apoapsis     = 
| orbit_inclination  = 
| apsis              = 
| interplanetary     = {{Infobox spaceflight/IP
   |type                = lander
   |object              = [[Moon|Lunar]]
   |arrival_date        = November 10, 1967, 01:01:06&nbsp;UTC
   |departure_date      = November 17, 1967, 10:32&nbsp;UTC
   |location            = {{Lunar coords and quad cat|0.46|N|1.37|W}}<ref name=":0">{{Cite web|title=In Depth {{!}} Surveyor 6|url=https://solarsystem.nasa.gov/missions/surveyor-6/in-depth|access-date=2022-01-07|website=NASA Solar System Exploration|date=December 27, 2017 }}</ref>
 }}
 {{Infobox spaceflight/IP
   |type                = lander
   |object              = [[Moon|Lunar]]
   |arrival_date        = November 17, 1967
   |location            = <small>{{convert|2.5|m}} west of original landing site</small><ref name=":0" />
 }}
| programme          = ''[[Surveyor program|Surveyor]]''
| previous_mission   = [[Surveyor 5]]
| next_mission       = [[Surveyor 7]]
}}
'''Surveyor 6''' is the sixth lunar lander of the [[United States|American]] uncrewed [[Surveyor program]] that reached the surface of the [[Moon]]. Surveyor 6 landed on the [[Sinus Medii]]. A total of 30,027 images were transmitted to Earth.

This spacecraft is the fourth of the Surveyor series to successfully achieve a soft landing on the Moon, obtain post landing television pictures, determine the abundance of the chemical elements in the lunar soil, obtain touchdown dynamics data, obtain thermal and radar reflectivity data, and conduct a [[Vernier thruster|Vernier engine]] erosion experiment. Virtually identical to Surveyor 5, this spacecraft carried a television camera, a small bar magnet attached to one footpad, and an alpha-scattering instrument as well as the necessary engineering equipment. It landed on November 10, 1967, in Sinus Medii, 0.49 deg in latitude and 1.40 deg w longitude ([[selenographic coordinates]])–the center of the Moon's visible hemisphere. The spacecraft accomplished all planned objectives. The successful completion of this mission satisfied the Surveyor program's obligation to the Apollo project. On November 24, 1967, the spacecraft was shut down for the two-week lunar night. Contact was made on December 14, 1967, but no useful data was obtained.

Lunar soil surveys were completed using photographic and [[alpha particle]] backscattering methods. A similar instrument, the [[APXS]], was used onboard several Mars missions.<ref>{{Cite web|url=http://mars.nasa.gov/msl/mission/instruments/spectrometers/apxs/|title=Alpha Particle X-Ray Spectrometer (APXS) – Mars Science Laboratory|last=NASA|first=JPL|website=mars.nasa.gov|access-date=November 25, 2016}}</ref>

In a further test of space technology, Surveyor 6's engines were restarted and burned for 2.5 seconds in the first lunar liftoff on November 17 at 10:32 UTC. This created 150&nbsp;lbf (700 N) of thrust and lifted the vehicle 12 feet (4 m) from the lunar surface. After moving west eight feet, (2.5 m) the spacecraft once again successfully soft landed and continued functioning as designed.

Surveyor 6 landed near the crash site of [[Surveyor 4]], which malfunctioned a few months earlier in July 1967.

== Science experiments ==

=== Television ===
The TV camera consisted of a [[vidicon]] tube, 25 and 100&nbsp;mm [[focal length]] lenses, [[Shutter (photography)|shutters]], [[Polarizing filter (Photography)|polarizing filter]]s (as opposed to [[color filter]]s used on the previous Surveyor cameras), and iris mounted nearly vertically and surmounted by a mirror that could be adjusted by stepping motors to move in both [[azimuth]] and elevation. The polarizing filters served as analyzers for the detection of measurement of the linearly polarized component of light scattered from the lunar surface. An auxiliary mirror was used for viewing the lunar surface beneath the spacecraft. 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 z axis to −60 deg below this same plane. 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. A complete video transmission of each 200 line picture required 20 seconds and utilized a [[Bandwidth (signal processing)|bandwidth]] of 1.2&nbsp;kHz. Most transmissions consisted of the 600 line pictures, which were telemetered by a [[directional antenna]]. 

The frames were scanned each 3.6 seconds. Each frame required nominally one second to be read from the vidicon and utilized a 220&nbsp;kHz bandwidth for transmission. The optical surfaces were the cleanest of any mission because of a redesigned mirror hood. The television images were displayed on a slow scan monitor coated with a long persistence [[phosphor]]. The persistence 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. The camera performance was excellent in terms of both the quantity and quality of pictures. Between lunar landing, lunar 'second' landing, and the lunar first day sunset on November 24, 1967, 29,914 pictures were taken and transmitted.
<gallery>
File:Surveyor 6 Fig 7-41d1.jpg|The mare surface
File:Surveyor 6 Fig 7-41d2.jpg|Another view of the mare surface
File:Surveyor 6 Effects-of-the-vernier-rock.jpg|Effects of the vernier-rocket engine blast on the double imprint previously made in the lunar surface by one of the spacecraft's crushable blocks during the initial touchdown.
File:Surveyor-7-effects-of-the-vernier-rocket engine blast.jpg|Effects of the vernier-rocket engine blast (before/after).
</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 100&nbsp;mm (3.94&nbsp;in) 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 particles scattered from the lunar surface, and the other, containing four sensors, detected energy spectra of the protons produced via reactions (alpha and protons) 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. Curium collected on the collimator films and was scattered by the gold plating on the inside bottom of the sensor head. This resulted in a gradually increasing background and reduction of the sensitivity technique for heavy elements. One proton detector was turned off during the second day of operation because of noise. A total of 43 hours of data was obtained from November 11 to 24, 1967. The final data was obtained 4 hours after local sunset. However, after the spacecraft 'hopping' maneuver on November 17, 1967, the sensor head was upside down. Measurements were continued in order to obtain information on solar protons and cosmic rays. Therefore, data for the purpose of the chemical analysis of lunar surface material were obtained only during the first 30 hours of operation. During this period, 27 hours and 44 min of data were known to be noise free.

=== Accomplishments ===
Surveyor 6 was the first spacecraft to lift off from another celestial body.<ref>{{cite book|url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |archive-url=https://web.archive.org/web/20190424211923/https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |archive-date=2019-04-24 |url-status=live|title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|page=1|last1=Siddiqi|first1=Asif A.|lccn=2017059404|isbn=9781626830424|publisher=NASA History Program Office|edition=second|year=2018|id=SP2018-4041|series=The NASA history series|location=Washington, DC}}</ref> It was monitored by the Jet Propulsion Laboratory in Pasadena. It used its liquid-fueled vernier engines to lift itself from its original landing site to a position some 10 feet away.<ref>[http://www.upi.com/Audio/Year_in_Review/Events-of-1967/Space-Successes/12303074818188-8/ "1967 Year In Review, UPI.com"]</ref>

This was later noted by the [[Mars Geyser Hopper]] mission as a post-soft landing propulsive hop that pre-dated its proposal.<ref name=mgh2012>{{cite web |url=http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4219.pdf |archive-url=https://web.archive.org/web/20160304003302/http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4219.pdf |archive-date=2016-03-04 |url-status=live |title=Concepts and Approaches for Mars Exploration (2012): ASRG Mars Geyser Hopper}}</ref>

{{Commons category}}

==See also==
* [[List of artificial objects on the Moon]]
* [[List of missions to the Moon]]

== References == 
{{reflist}}

{{Portal|Spaceflight}}
{{Surveyor program}}
{{Lunar landers}}
{{Moon spacecraft}}
{{Orbital launches in 1967}}
{{NASA space program}}

{{Use American English|date=January 2014}}

[[Category:Surveyor program (NASA)|6]]
[[Category:Spacecraft launched in 1967]]
[[Category:Missions to the Moon]]
[[Category:Spacecraft launched by Atlas-Centaur rockets]]
[[Category:Soft landings on the Moon]]
[[Category:Hopping spacecraft]]
[[Category:1967 on the Moon]]