Editing Surveyor program

{{short description|1960s NASA program to soft-land robotic probes on the Moon}}
{{Use American English|date=November 2020}}
{{Use mdy dates|date=November 2020}}
{{Infobox space program
| name = Surveyor program
| image = Surveyor diagram(English captions).jpg
| image_size = 
| alt = 
| caption = Surveyor 3 resting on the surface of the Moon, taken by [[Apollo 12]] astronauts
| country = United States
| organization = [[NASA]]
| purpose = Demonstrate [[Lunar landing|soft landing on the Moon]]
| status = Completed
| cost = US$469 million
| duration = 
| firstflight = May 30–June 2, 1966
| lastflight = January 7–10, 1968
| successes = 5
| failures = 2
| partialfailures = 
| launchsite = [[Cape Canaveral Air Force Station Space Launch Complex 36|Cape Canaveral LC-36]]
| crewvehicle = 
| launcher = [[Atlas-Centaur]]
}}
The '''Surveyor program''' was a [[NASA]] program that, from June 1966 through January 1968, sent seven [[robotic spacecraft]] to the surface of the [[Moon]]. Its primary goal was to demonstrate the feasibility of [[Soft landing (rocketry)|soft landings]] on the Moon. The Surveyor craft were the first American spacecraft to achieve soft landing on an [[Astronomical object|extraterrestrial body]]. The missions called for the craft to travel directly to the Moon on an impact trajectory, a journey that lasted 63 to 65 hours, and ended with a deceleration of just over three minutes to a soft landing.<ref name=Kloman1972/> 

The program was implemented by NASA's [[Jet Propulsion Laboratory]] (JPL) to prepare for the [[Apollo program]], and started in 1960. JPL selected Hughes Aircraft in 1961 to develop the spacecraft system.<ref name=Kloman1972>{{cite web|id=NASA SP-4901 |url=https://history.nasa.gov/SP-4901.pdf  |title=''NASA Unmanned Space Project Management - Surveyor and Lunar Orbiter'' |author=Kloman |year=1972}}</ref>  The total cost of the Surveyor program was officially $469 million.

Five of the Surveyor craft successfully soft-landed on the Moon, including the first one. The other two failed: Surveyor 2 crashed at high velocity after a failed mid-course correction, and Surveyor 4 lost contact (possibly exploding) 2.5 minutes before its scheduled touch-down.

All seven spacecraft are still on the Moon; none of the missions included returning them to Earth.  Some parts of [[Surveyor 3]] were returned to Earth by the crew of [[Apollo 12]], which landed near it in 1969.  The camera from this craft is on display at the [[National Air and Space Museum]] in Washington, DC.<ref name="auto">https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-035A – 24 January 2020</ref>

== Goals ==
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The program performed several other services beyond its primary goal of demonstrating soft landings.  The ability of spacecraft to make midcourse corrections was demonstrated, and the landers carried instruments to help evaluate the suitability of their landing sites for crewed Apollo landings. Several Surveyor spacecraft had robotic shovels designed to test lunar soil mechanics. Before the Soviet [[Luna 9]] mission (landing four months before Surveyor 1) and the Surveyor project, it was unknown how deep the dust on the Moon was. If the dust was too deep, then no astronaut could land. The Surveyor program proved that landings were possible. Some of the Surveyors also had [[Alpha particle scattering|alpha scattering]] instruments and magnets, which helped determine the chemical composition of the soil.

The simple and reliable mission architecture was a pragmatic approach to solving the most critical space engineering challenges of the time, namely the closed-loop terminal descent guidance and control system, throttleable engines, and the radar systems required for determining the lander's altitude and velocity. The Surveyor missions were the first time that [[NASA]] tested such systems in the challenging thermal and radiation environment near the Moon.

== Launch and lunar landing ==
{{refimprove section|date=September 2020}}
[[File:1965 Typical Atlas Centaur Stages.jpg|thumb|[[Atlas-Centaur]] injecting a Surveyor lander directly into trans-lunar flightpath]]
Each Surveyor mission consisted of a single unmanned spacecraft designed and built by [[Hughes Aircraft Company]]. The launch vehicle was the [[Atlas-Centaur]], which injected the craft directly into trans-lunar flightpath. The craft did not orbit the Moon on reaching it, but directly decelerated from impact trajectory, from 2.6&nbsp;km/s relative to the Moon before firing retrorockets to a soft landing about 3 minutes 10 seconds later.

Each craft was planned to slow to about 110&nbsp;m/s (4% of speed before retrofire) by a main solid fuel retrorocket, which fired for 40 seconds starting at an altitude of 75.3&nbsp;km above the Moon, and then was jettisoned along with the radar unit at 11&nbsp;km from the surface. The remainder of the trip to the surface, lasting about 2.5 minutes, was handled by smaller doppler radar units and three [[Vernier thruster|vernier engines]] running on liquid fuels fed to them using pressurized helium. (The successful flight profile of Surveyor 5 was given a somewhat shortened vernier flight sequence as a result of a helium leak.) The last 3.4 meters to the surface was accomplished in free fall from zero velocity at that height, after the vernier engines were turned off. This resulted in a landing speed of about 3&nbsp;m/s. The free-fall to the surface was in an attempt to avoid surface contamination by rocket blast.

Surveyor 1 required a total of about 63 hours (2.6 days) to reach the Moon, and Surveyor 5 required 65 hours (2.7 days). The launch weights (at lunar injection) of the seven Surveyors ranged from {{convert|995.2|kg}} to {{convert|1040|kg}}, and their landing weights (minus fuel, jettisoned retrorocket, and radar unit) ranged from {{convert|294.3|kg}} to {{convert|306|kg}}.

== Missions ==

=== Surveyor 1 ===
{{Main|Surveyor 1}}
[[File:Surveyor 1 Foot Pad.jpg|thumb|Image from Surveyor 1 of its footpad in order to study [[soil mechanics]] in preparation for the Apollo crewed landings.]]
'''[[Surveyor 1]]''' was launched May 30, 1966 and sent directly into a trajectory to the Moon without any [[parking orbit]]. Its [[Retrorocket|retrorockets]] were turned off at a height of about 3.4 [[Meter|meters]] above the lunar surface. Surveyor 1 fell freely to the surface from this height, and it landed on the lunar surface on June 2, 1966, on the ''Oceanus Procellarum''. This location was at {{Lunar coords and quad cat|2.474|S|43.339|W}}.<ref>"[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-045A Surveyor 1]". NASA Space Science Data Coordinated Archive.</ref>  This is within the northeast portion of the large crater called Flamsteed P (or the ''Flamsteed Ring'').  [[Flamsteed (crater)|Flamsteed]] itself lies within Flamsteed P on the south side.

Surveyor 1 transmitted [[video]] data from the Moon beginning shortly after its landing through July 14, 1966, but with a period of no operations during the two-week long lunar night of June 14, 1966 through July 7, 1966. 

The return of engineering information (temperatures, etc.) from Surveyor 1 continued through January 7, 1967, with several interruptions during the lunar nights. The spacecraft returned data on the motion of the Moon, which would be used to refine the map of its orbital path around the Earth as well as better determine the distance between the two worlds.<ref name="aa1967">{{cite web |title=Aeronautics and Astronautics, 1967 |url=https://history.nasa.gov/AAchronologies/1967.pdf |access-date=21 December 2021 |publisher=NASA |page=5}}</ref>

=== Surveyor 2 ===
{{Main|Surveyor 2}}
'''[[Surveyor 2]]''' was launched on September 20, 1966. A mid-course correction failure resulted in the spacecraft losing control.<ref>"Central Moon Landing Try for Surveyor 2". ''The Deseret News''. 19 September 1966. </ref><ref name=":0">{{Cite web |title=Surveyor 2 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-084A |website=NSSDCA Master Catalog}}</ref> Contact was lost with the spacecraft at 9:35 UTC, September 22.<ref name=":0" />

=== Surveyor 3 ===
{{Main|Surveyor 3}}
[[Image:Apollo12ConradSurveyor.jpg|thumb|Astronaut [[Pete Conrad]] near Surveyor 3 during Apollo 12, 1969. [[Apollo Lunar Module|Lunar Module]] in the background.]]Launched on April 17, 1967, '''[[Surveyor 3]]''' landed on April 20, 1967, at the [[Mare Cognitum]] portion of the [[Oceanus Procellarum]] (S3° 01' 41.43" W23° 27' 29.55"), in a small crater that was subsequently named [[Surveyor (crater)|Surveyor]]. It transmitted 6,315 TV images to the Earth, including the [[First images of Earth from space|first images to show what planet Earth looked like from the Moon's surface]].<ref>{{Cite web |title=First image of Earth from the surface of the Moon: Surveyor 3 |url=https://www.planetary.org/space-images/first-image-of-earth-from-surveyor-3}}</ref>

Surveyor 3 was the first spacecraft to unintentionally lift off from the Moon's surface, which it did twice, due to an anomaly with Surveyor's landing radar, which did not shut off the vernier engines but kept them firing throughout the first touchdown and after it. Surveyor 3's TV and telemetry systems were found to have been damaged by its unplanned landings and liftoffs.<ref name="auto" />

Surveyor 3 was visited by [[Apollo 12]] astronauts [[Pete Conrad]] and [[Alan Bean]] in November 1969, and remains the only probe visited by humans on another [[Astronomical object|world]]. The Apollo 12 astronauts excised several components of Surveyor 3, including the television camera, and returned them to Earth for study.<ref>{{Cite web |author1=Robert Z. Pearlman |date=2019-11-23 |title=50 Years On, Where Are the Surveyor 3 Moon Probe Parts Retrieved by Apollo 12? |url=https://www.space.com/apollo-12-surveyor-3-parts-50-years.html |access-date=2024-10-02 |website=Space.com |language=en}}</ref>

=== Surveyor 4 ===
{{Main|Surveyor 4}}
Launched on July 14, 1967, '''[[Surveyor 4]]''' crashed after an otherwise flawless mission; [[telemetry]] contact was lost 2.5 minutes before touchdown. The [[Solid-fuel rocket|solid-fuel]] [[retrorocket]] may have exploded near the end of its scheduled burn.<ref>{{Cite web |title=Surveyor 4 |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-068A |website=NSSDCA Master Catalog}}</ref> The planned landing target was [[Sinus Medii]] (Central Bay) at 0.4° north latitude and 1.33° west longitude.

=== Surveyor 5 ===
{{Main|Surveyor 5}}
[[File:Surveyor 5 Fig 7-41c2.jpg|thumb|Lunar surface imaged by [[Surveyor 5]]]]
'''[[Surveyor 5]]''' was launched on September 8, 1967 from Cape Canaveral.<ref>{{Cite web |title=NASA - NSSDCA - Spacecraft - Telemetry Details |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1967-084A |access-date=March 30, 2019 |website=nssdc.gsfc.nasa.gov}}</ref> It landed on [[Mare Tranquillitatis]] on September 11, 1967. The spacecraft transmitted excellent data for all experiments from shortly after touchdown until October 18, 1967, with an interval of no transmission from September 24 to October 15, 1967, during the first lunar night. Transmissions were received until November 1, 1967, when shutdown for the second lunar night occurred. Transmissions were resumed on the third and fourth lunar days, with the final transmission occurring on December 17, 1967. A total of 19,118 images were transmitted to Earth.<ref>{{Cite web |title=NASA - NSSDCA - Spacecraft - Details |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-084A |access-date=March 30, 2019 |website=nssdc.gsfc.nasa.gov}}</ref> 

=== Surveyor 6 ===
{{Main|Surveyor 6}}
[[File:Surveyor 6 Effects-of-the-vernier-rock.jpg|thumb|Surveyor 6 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]]
'''[[Surveyor 6]]''' was the first spacecraft planned to lift off from the Moon's surface.<ref>{{cite book |last1=Siddiqi |first1=Asif A. |url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016 |publisher=NASA History Program Office |year=2018 |isbn=9781626830424 |edition=second |series=The NASA history series |location=Washington, DC |page=1 |lccn=2017059404 |id=SP2018-4041 |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}}</ref>

It was launched on November 7, 1967, and landed on November 10, 1967 in Sinus Medii (near the crash site of [[Surveyor 4]]). The successful completion of this mission satisfied the Surveyor program's obligation to the Apollo project.

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 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. 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.

=== Surveyor 7 ===
{{Main|Surveyor 7}}
[[File:Tycho Crater Panorama.jpg|thumb|Photomosaic of lunar panorama near the Tycho crater taken by Surveyor 7. The hills on the center horizon are about eight miles away from the spacecraft.]]
'''[[Surveyor 7]]''' was launched on January 7, 1968, landing on the [[lunar surface]] on January 10, 1968, on the outer rim of the [[Tycho (lunar crater)|crater Tycho]]. Operations of the spacecraft began shortly after the soft landing. On January 20, while the craft was still in daylight, the TV camera clearly saw two laser beams aimed at it from the night side of the crescent Earth, one from Kitt Peak National Observatory, Tucson, Arizona, and the other at Table Mountain at Wrightwood, California.<ref>{{cite web |title=Boeing: Satellite Development Center - Scientific Exploration - Surveyor |url=http://www.boeing.com/defense-space/space/bss/factsheets/scientific/surveyor/surveyor.html |url-status=dead |archive-url=https://web.archive.org/web/20100207072958/http://boeing.com/defense-space/space/bss/factsheets/scientific/surveyor/surveyor.html |archive-date=2010-02-07 |access-date=2010-03-31}} Notes on the laser experiment.</ref><ref>[http://www.w7ftt.net/laser2.html] photo of the beam from the 2-watt green argon Hughes laser at Table Mountain</ref>

Operations on the second lunar day occurred from February 12 to 21, 1968. The mission objectives were fully satisfied by the spacecraft operations. Battery damage was suffered during the first lunar night and transmission contact was subsequently sporadic. Contact with Surveyor 7 was lost on February 21, 1968.<ref>{{cite web |date=28 November 2017 |title=Surveyor VII |url=https://www.lpl.arizona.edu/sic/surveyor/7 |access-date=11 April 2021 |website=University of Arizona Lunar and Planetary Laboratory}}</ref>

== Surveyor mission list ==
[[File:Surveyor-Model 1 (NASA).jpg|thumb|Surveyor-Model 1: A 952 kg mass representative for the Surveyor lunar probe. The cylindrical mass was permanently connected to the Centaur upper stage. ]]
[[File:Surveyor-SD 2.jpg|thumb|Surveyor-SD 2. Simulated Surveyor payload with the same dynamic properties as the real probe.]]
Surveyor-Model were generic mass simulators,<ref name=":1">{{Cite web |title=Surveyor Model 1 - NASA Science |url=https://science.nasa.gov/mission/surveyor-model-1/ |access-date=2024-10-02 |website=science.nasa.gov |date=December 27, 2017 |language=en-US}}</ref><ref name=":2">{{Cite web |title=Surveyor-Model |url=https://space.skyrocket.de/doc_sdat/surveyor-model.htm |access-date=2024-10-02 |website=Gunter's Space Page |language=en}}</ref> while Surveyor SD had the same structure as the real Surveyor landers with all equipment replaced by dummy weights.<ref name=":3">{{Cite web |title=Surveyor-SD |url=https://space.skyrocket.de/doc_sdat/surveyor-sd.htm |access-date=2024-10-02 |website=Gunter's Space Page |language=en}}</ref> These served to test [[Atlas-Centaur]] launch vehicle performance, and were not intended to reach the Moon.<ref name=":1" /><ref name=":2" /><ref name=":3" /> 

Of the seven Surveyor missions, five were successful. 
{| class="wikitable sortable"
|-
! Mission
! Launch
!Rocket
! Arrived at Moon
! Disposition
|-
|Surveyor-Model 1
|December 11, 1964
|[[Atlas-Centaur#Fourth flight|Atlas-LV3C Centaur-C AC-4]]
| -
|165 × 178 km Earth orbit
|-
|Surveyor SD-1
|March 02, 1965
|[[Atlas-Centaur#Fifth flight|Atlas-LV3C Centaur-C AC-5]]
| -
|destroyed on launch
|-
|Surveyor SD-2
|August 11, 1965
|[[Atlas-Centaur#Later flights|Atlas-LV3C Centaur-D AC-6]]
| -
|166 × 815085 km Earth orbit
|-
|Surveyor-Model 2 
|April 08, 1966
|Atlas-LV3C Centaur-D AC-8
| -
|175 × 343 km Earth orbit
|-
| [[Surveyor 1]]
| May 30, 1966
|Atlas-LV3C Centaur-D AC-10
| June 2, 1966
| landed on [[Oceanus Procellarum]]
|-
| [[Surveyor 2]] 
| September 20, 1966
|Atlas-LV3C Centaur-D AC-7
| September 23, 1966
| crashed near [[Copernicus (lunar crater)|Copernicus crater]]
|-
|Surveyor-Model 3
|October 26,1966
|Atlas-LV3C Centaur-D AC-9
| -
|165 × 470040 km Earth orbit
|-
| [[Surveyor 3]]
| April 17, 1967
|Atlas-LV3C Centaur-D AC-12
| April 20, 1967
| landed on [[Oceanus Procellarum]]
|-
| [[Surveyor 4]]
| July 14, 1967
|Atlas-LV3C Centaur-D AC-11
| July 17, 1967
| crashed on [[Sinus Medii]]
|-
| [[Surveyor 5]]
| September 8, 1967
|[[Atlas SLV-3#SLV-3C|Atlas-SLV3C Centaur-D]] AC-13
| September 11, 1967
| landed on [[Mare Tranquillitatis]]
|-
| [[Surveyor 6]]
| November 7, 1967
|Atlas-SLV3C Centaur-D AC-14
| November 10, 1967
| landed on [[Sinus Medii]]
|-
| [[Surveyor 7]]
| January 7, 1968
|Atlas-SLV3C Centaur-D AC-15
| January 10, 1968
| landed near [[Tycho (lunar crater)|Tycho crater]]
|}

== Space Race competition ==
[[File:NASM-SI-2007-29754.jpg|thumb|An engineering model of Surveyor 3, S-10, used for thermal control tests. It was reconfigured to represent a flight model of Surveyor 3 or later, since it was the first to have a scoop and claw surface sampler. (National Air and Space Museum)]]

During the time of the Surveyor missions, the [[United States]] was actively involved in the [[Space Race]] with the [[Soviet Union]]. Thus, the Surveyor 1 landing in June 1966, only four months after the Soviet [[Luna 9]] probe landed in February, was an indication the programs were at similar stages.<ref name="Reeves1994">{{cite book |last1=Reeves |first1=Robert |title=The superpower space race: An explosive rivalry through the solar system |date=1994 |publisher=Springer |location=Boston, MA, USA |isbn=978-1-4899-5986-7 |pages=101–130 |chapter-url=https://doi.org/10.1007/978-1-4899-5986-7_4 |chapter=Exploring the Moon|doi=10.1007/978-1-4899-5986-7_4 }}</ref>

==See also==
*[[Atlas (rocket family)]]
*[[Luna programme]]
*[[Lunar Orbiter program]]
*[[Ranger program]]
*[[Exploration of the Moon]]
*[[List of missions to the Moon]]

== References ==
{{reflist|2}}

==External links==
{{Commons|Surveyor program}}
*[http://nssdc.gsfc.nasa.gov/planetary/lunar/surveyor.html Surveyor (1966–1968)]
*[https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690027073_1969027073.pdf Surveyor Program Results (PDF) 1969]
*[https://archive.org/details/surveyorprogramr00unit Surveyor Program Results (Good Quality Color PDF) 1969]
*[https://ntrs.nasa.gov/api/citations/19720019081/downloads/19720019081.pdf Analysis of Surveyor 3 material and photographs returned by Apollo 12 (PDF) 1972]
*[http://www.lpi.usra.edu/expmoon/surveyor/surveyor.html Exploring the Moon: The Surveyor Program]
*[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-045A Details of Surveyor 1 launch, and also the entire program]
*[https://www.lpl.arizona.edu/sic/surveyor Digitizing the Surveyor Lander Imaging Dataset] | Lunar and Planetary Laboratory & Department of Planetary Sciences | The University of Arizona

{{Surveyor program|before=[[Ranger program|Ranger]]|after=''None, see contemporaneous program [[Lunar Orbiter program|Lunar Orbiters]]''}}
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{{Use American English|date=January 2014}}

[[Category:Surveyor program (NASA)|*]]
[[Category:Missions to the Moon]]
[[Category:Derelict landers (spacecraft)]]