Discoverer 31

{{Infobox spaceflight

| name = Discoverer 31

| image =

| image_caption =

| mission_type = Optical reconnaissance

| operator = US Air Force/NRO

| Harvard_designation = 1961 Alpha Beta 1

| SATCAT =

| mission_duration = 2 days

| spacecraft =

| spacecraft_type = KH-3 Corona'''

| spacecraft_bus = Agena-B

| manufacturer = Lockheed

| launch_mass = {{convert|1150|kg}}

| launch_date = {{start-date|17 September 1961, 21:00|timezone=yes}} UTC

| launch_rocket = Thor DM-21 Agena-B 324

| launch_site = Vandenberg LC-75-1-1

| decay_date = {{end-date|26 October 1961}}

| landing_date =

| landing_site =

| orbit_epoch =

| orbit_reference = Geocentric

| orbit_regime = Low Earth

| orbit_periapsis = {{convert|233|km|mi|sp=us}}

| orbit_apoapsis = {{convert|380|km|mi|sp=us}}

| orbit_inclination = 82.7 degrees

| orbit_period = 90.7 minutes

| apsis = gee

}}

File:Thor Agena B with Discoverer 31 (Sep. 17, 1961).gif

Discoverer 31, also known as Corona 9024, was an American optical reconnaissance satellite which was launched in 1961. It was a KH-3 Corona''' satellite, based on an Agena-B.{{cite web|url=http://space.skyrocket.de/doc_sdat/kh-3.htm|title=KH-3 Corona|first=Gunter|last=Krebs|publisher=Gunter's Space Page|accessdate=29 June 2010}}

The launch of Discoverer 31 occurred at 21:00 UTC on 17 September 1961. A Thor DM-21 Agena-B rocket was used, flying from Launch Complex 75-1-1 at the Vandenberg Air Force Base.{{cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|first=Jonathan|last=McDowell|publisher=Jonathan's Space Page|accessdate=29 June 2010}} Upon successfully reaching orbit, it was assigned the Harvard designation 1961 Alpha Beta 1.

Discoverer 31 was operated in a low Earth orbit, with a perigee of {{convert|233|km}}, an apogee of {{convert|380|km}}, 82.7 degrees of inclination, and a period of 90.7 minutes.{{cite web|url=http://planet4589.org/space/log/satcat.txt|title=Satellite Catalog|first=Jonathan|last=McDowell|publisher=Jonathan's Space Page|accessdate=29 June 2010}} The satellite had a mass of {{convert|1150|kg}},{{cite web|url=http://www.astronautix.com/craft/kh3.htm|title=KH-3|first=Mark|last=Wade|publisher=Encyclopedia Astronautica|accessdate=29 June 2010|url-status=dead|archiveurl=https://web.archive.org/web/20100918005311/http://astronautix.com/craft/kh3.htm|archivedate=18 September 2010}} and was equipped with a panoramic camera with a focal length of {{convert|61|cm}}, which had a maximum resolution of {{convert|7.6|m}}.{{cite web|url=http://msl.jpl.nasa.gov/programs/corona.html|title=Corona|publisher=NASA|work=Mission and Spacecraft Library|accessdate=29 June 2010|url-status=dead|archiveurl=https://web.archive.org/web/20071003082210/http://msl.jpl.nasa.gov/Programs/corona.html|archivedate=3 October 2007}} Images were recorded onto {{convert|70|mm|adj=on|sp=us}} film, and were to have been returned in a Satellite Recovery Vehicle. The Satellite Recovery Vehicle carried aboard Discoverer 31 was SRV-552. During the spacecraft's thirty-third orbit, the attitude control and power systems malfunctioned, and as a result Discoverer 31 was unable to complete its mission or return images.{{cite web|url=http://www.fas.org/spp/military/program/imint/kh-3.htm|title=KH-3 Corona|first=Christina|last=Lindborg|first2=John|last2=Pike|date=9 September 2000|accessdate=29 June 2010|publisher=Federation of American Scientists}} It decayed from orbit on 26 October 1961.

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