Lunar Orbiter 2

{{short description|NASA orbiter mission to the Moon (1966–1967)}}

{{Infobox spaceflight

| name = Lunar Orbiter 2

| image = NASM-A19700318000-NASM2018-00097.jpg

| image_caption = Replica of a Lunar Orbiter spacecraft

| image_size = 300px

| mission_type = Lunar orbiter

| operator = NASA

| COSPAR_ID = 1966-100A

| SATCAT = 2534

| website = [https://science.nasa.gov/mission/lunar-orbiters-program/ science.nasa.gov]

| mission_duration = {{time interval|6 Nov 1966|11 Oct 1967|sep=,}}

| manufacturer = Langley Research Center

| launch_mass = {{cvt|385.6|kg|lb}}

| dimensions = {{cvt|3.72|xx|1.65|xx|1.5|m|ft}}

| power = 375 watts

| launch_date = {{start-date|November 6, 1966, 23:21:00|timezone=yes}} UTC

| launch_rocket = Atlas SLV-3 Agena-D

| launch_site = Cape Canaveral LC-13

| disposal_type = Deorbited

| decay_date = {{end-date|October 11, 1967, 07:12:54}} UTC

| orbit_epoch = November 9, 1966, 19:00:00 UTC

| orbit_reference = Selenocentric

| orbit_periapsis = {{cvt|1790|km|mi}}

| orbit_apoapsis = {{cvt|3598|km|mi}}

| orbit_inclination = 11.9 degrees

| orbit_period = 208.07 minutes

| orbit_semimajor = {{cvt|2694|km|mi}}

| orbit_eccentricity = 0.35

| apsis = selene

| trans_frequency = 2295 MHz

| instruments_list =

{{Infobox spaceflight/Instruments

|acronym1 = - | name1 = Cesium Iodide Dosimeters

|acronym2 = - | name2 = Lunar Photographic Studies

|acronym3 = - | name3 = Meteoroid Detectors{{r|nssdc4|nssdc5}}

|acronym4 = - | name4 = Selenodesy

}}

|interplanetary =

{{Infobox spaceflight/IP

|type = orbiter

|object = Lunar

|orbits = 2,346

|arrival_date = November 10, 1966

|location = {{Lunar coords and quad cat|3.0|N|119.1|E}}

}}

| programme = Lunar Orbiter program

| previous_mission = Lunar Orbiter 1

| next_mission = Lunar Orbiter 3

}}

The 1966 Lunar Orbiter 2 robotic spacecraft mission, part of the Lunar Orbiter Program, was designed primarily to photograph smooth areas of the lunar surface for selection and verification of safe landing sites for the Surveyor and Apollo missions. It was also equipped to collect selenodetic, radiation intensity, and micrometeoroid impact data.

Mission summary

The spacecraft was placed in a cislunar trajectory and injected into an elliptical near-equatorial lunar orbit for data acquisition after 92.6 hours' flight time. The initial orbit was {{convert|196|x|1850|km}} at an inclination of 11.8 degrees. The perilune was lowered to {{convert|49.7|km}} five days later after 33 orbits. A failure of the amplifier on the final day of readout, December 7, resulted in the loss of six photographs. On December 8, 1966 the inclination was altered to 17.5 degrees to provide new data on lunar gravity.

File:Lunar Orbiter 2 coverage.jpg

The spacecraft acquired photographic data from November 18 to 25, 1966, and readout occurred through December 7, 1966. A total of 609 high-resolution and 208 medium-resolution frames were returned, most of excellent quality with resolutions down to {{convert|1|m}}.{{r|lpi2|Hansen_1970}} These included a spectacular oblique picture of Copernicus crater, which was dubbed by the news media as one of the great pictures of the century. The photo was taken on the 23rd November at an altitude of 45km. Accurate data were acquired from all other experiments throughout the mission. Three micrometeorite impacts were recorded. The spacecraft was used for tracking purposes until it impacted upon the lunar surface on command at 3.0 degrees N latitude, 119.1 degrees E longitude (selenographic coordinates) on October 11, 1967.

In 2011, NASA's Lunar Reconnaissance Orbiter Camera (LROC) was able to locate and image the precise impact point of the spacecraft. The debris from an impact angle of 45 degrees or more spreads out like butterfly wings.

class="wikitable" \|+Instruments
Lunar Photographic Studies \| Evaluation of Apollo and Surveyor landing sites
Meteoroid Detectors \| Detection of micrometeoroids in the lunar environment
Caesium Iodide Dosimeters \| Radiation environment en route to and near the Moon
Selenodesy \| Gravitational field and physical properties of the Moon

class="wikitable"

|+Instruments

Lunar Photographic Studies

| Evaluation of Apollo and Surveyor landing sites

Meteoroid Detectors

| Detection of micrometeoroids in the lunar environment

Caesium Iodide Dosimeters

| Radiation environment en route to and near the Moon

Selenodesy

| Gravitational field and physical properties of the Moon

Image:Lunar Orbiter 2 - FRAME 2061-H2 - DPLA - 931596a9929c4975efc42a4ebddd6e90.jpg|Near Ariadaeus B crater on November 19, 1966 ({{coord|4.83|N|15.53|E|globe:moon_type:landmark}})

Image:Lunar Orbiter 2 - FRAME 2145-H2 - DPLA - 33b1de52dc6aae6be89811d9d028e037.jpg|Area east of Gambart crater on November 23, 1966 ({{coord|1.07|N|12.45|W|globe:moon_type:landmark}})

Image:Lunar Orbiter 2 - FRAME 2192-H1 - DPLA - 5d6bbd8cc1afb76ea2c4dfdda0b6a941.jpg|Part of Mare Insularum, southwest of Kunowsky crater, on November 24, 1966 ({{coord|1.87|N|33.79|W|globe:moon_type:landmark}})

References

{{reflist|refs=

{{cite book

| author1= B. A. Byers

| title= Destination Moon: A History of the Lunar Orbiter Program

| url= https://ntrs.nasa.gov/citations/19770016195

| publisher= NASA

| date= 1976

| access-date= 12 November 2022

| isbn= 978-1-495-92029-5

| id= NASA-TM-X-3487 }}

{{cite book

| author1= Thomas P. Hansen

| title= Guide to Lunar Orbiter Photographs

| url= https://ntrs.nasa.gov/citations/19710026703

| publisher= NASA

| date= 1970

| access-date= 13 November 2022

| isbn= 978-1-499-16108-3

| id= NASA-SP-242 }}

{{cite web

| url= http://www.lpi.usra.edu/resources/lunarorbiter/mission/?2

| title= Lunar Orbiter Photo Gallery - Mission 2

| publisher= Lunar and Planetary Institute

| access-date= 13 November 2022 }}

{{cite web

| title= Lunar Orbiter 2

| url= https://science.nasa.gov/mission/lunar-orbiter-2/

| website= science.nasa.gov

| date= December 8, 2017

| publisher= NASA

| access-date= 30 November 2022 }}

{{cite web

| title= Lunar Orbiter 2

| url= https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-100A