Skylab 4 Observed Comet Kohoutek November 1973 to February 1974

Summary: Skylab 4 observed Comet Kohoutek November 1973 to February 1974 via 13 experiments during the recently discovered comet’s perihelion passage.

geometry of perihelion observation of Comet Kohoutek; C.A. Lundquist, Skylab’s Astronomy and Space Sciences (1979), Figure 4-8, page 48: "Work of the US Gov. Public Use Permitted," via NASA History

Skylab 4 observed Comet Kohoutek November 1973 to February 1974 via 13 experiments that maximized the compatibility of the recently discovered comet’s trajectory with Skylab space station’s orbit during Comet Kohoutek’s perihelion passage.

Czech astronomer Luboš Kohoutek (born Jan. 29, 1935) made his cometary discovery while examining photographic plates taken Wednesday, March 7, 1973. The long-period comet’s discovery preceded Comet Kohoutek’s calculated perihelion on Friday, Dec. 28, 1973, by nine and two-thirds months. NASA Marshall Space Flight Center’s MSFC Skylab Kohoutek Project Report (1974) noted the comet’s early discovery as “. . . unprecedented and allowed sufficient time for large-scale, coordinated planning of observational programs” (page 2).

The National Aeronautics and Space Administration (NASA) finessed the Skylab 4 mission’s time frame for maximum compatibility with Comet Kohoutek’s perihelion (Ancient Greek: περί, perí, “near” + ἥλιος, hḗlios, “sun”) passage. The mission’s observation program involving the station’s scientific airlock (SAL), handheld photography (HH) and extravehicular activity (EVA) was scheduled to run from Sunday, Nov. 25, 1973, to Saturday, Feb. 2, 1974. Less sensitive experiments, which utilized the station’s solar observatory, the Apollo Telescope Mount (ATM), for direct looks at the sun, were scheduled to occur between Dec. 14, 1973.

Skylab 4, NASA’s third and last manned mission to the first United States space station, launched Friday, Nov. 16, 1973, at 14:01:23 Coordinated Universal Time (9:01 a.m. Eastern Standard Time) from east central Florida’s John F. Kennedy Space Center. The mission’s Apollo Command and Service Module (CSM) 118 docked at the space station at 21:55:00 UTC (4:55 p.m. EST).

All three of the Skylab 4 astronauts made their first and only career spaceflights via the mission. Gerald Paul Carr (born Aug. 22, 1932) commanded Skylab 4. Edward George Gibson (born Nov. 8, 1936) and William Reid Pogue (Jan. 23, 1930-March 3, 2014) flew as scientist pilot and pilot, respectively.

Instruments for all but one of the 13 Comet Kohoutek-based experiments conducted by the astronauts already existed as experiment hardware in the space station’s inventory. The astronauts brought with them a far-ultraviolet electrographic camera, which had been designed and built as backup for the Apollo 16 mission of April 1972 and which was modified for use at Skylab.

The Skylab 4 mission’s first Kohoutek-based experiment was Experiment S233, Kohoutek photometric photography. The experiment was conducted from Friday, Nov. 23, 1973, to Tuesday, Feb. 5, 1974.

Two other Kohoutek experiments commenced in November. Experiment S201, hydrogen halo growth and structure with heliocentric distance, operated with 14 sessions from Monday, Nov. 26, 1973, to Wednesday, Jan. 2, 1974. Experiment S019, ultraviolet (UV) absorption and emission spectra, comprised 14 sessions between Sunday, Nov. 25, 1973, and Wednesday, Jan. 30, 1974.

Ten Kohoutek experiments were started in December. Early December was the start date for two of the month’s experiments. Between Thursday, Dec. 6, 1973, and Monday, Jan. 28, 1974, Experiment S063, UV polarimetry and bandpass photography of the comet’s coma and tail, operated 22 sessions. Between Friday, Dec. 7, 1973, and Friday, Jan. 11, 1974, six sessions were conducted for Experiment S183, ultraviolet, broad bandpass photographic photometry of the coma and tail.

Two experiments required only one session. Experiment S073, cometary particle distribution, had one session Monday, Dec. 10. A single session Thursday, Dec. 27, gathered data for Experiment S082A, chemical composition, especially of neutral and ionized helium and of ionized oxygen.

Dec. 19 was the start date for four experiments. Operational dates from Wednesday, Dec. 19, 1973, through Monday, Jan. 7, 1974, were observed for Experiment S052, dust-production rates and grain-size distribution; Experiment S055, hydrogen emission in Kohoutek’s hydrogen halo; Experiment S056, solar x-ray-excited soft x-ray fluorescence; and Experiment S082B, spectral intensities.

Two experiments were started during Christmas week. Experiment T025, UV and visible bandpass photography of the coma and tail, entailed two sessions via EVAs (extravehicular activities), pre-perihelion on Tuesday, Dec. 25, and post-perihelion, on Saturday, Dec. 29. Experiment S054, comet tail’s x-ray absorption spectra and coma’s x-ray fluorescence imagery, Thursday, Dec. 27, 1973, and Sunday, Jan. 6, 1974.

The first Kohoutek-based experiment, Experiment 233, which began Friday, Nov. 23, 1973, lasted the longest and ended the latest. The experiment’s last frame was obtained at 01:03 UTC, Tuesday, Feb. 5, 1974 (9:03 p.m. Eastern Daylight Time, Monday, Feb. 4, 1974).

Three days later, Friday, Feb. 8, 1974, at 02:33:12 (Thursday, Feb. 7, at 10:33 p.m. Eastern Daylight Time), CSM 118 undocked. The mission’s three astronauts had set a record for Skylab occupation of 83 days 4 hours 38 minutes 12 seconds.

The takeaways for Skylab 4 observing Comet Kohoutek November 1973 to February 1974 are that NASA’s third manned mission’s time parameters were scheduled for compatibility with Comet Kohoutek’s perihelion passage and that 13 Kohoutek-based experiments were conducted between Friday, Nov. 23, 1973, and Tuesday, Feb. 5, 1974.

geometry of post-perihelion observation of Comet Kohoutek; C.A. Lundquist, Skylab’s Astronomy and Space Sciences (1979), Figure 4-9, page 49: "Work of the US Gov. Public Use Permitted," via NASA History

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

geometry of perihelion observation of Comet Kohoutek; C.A. Lundquist, Skylab’s Astronomy and Space Sciences (1979), Figure 4-8, page 48: "Work of the US Gov. Public Use Permitted," via NASA History @ https://history.nasa.gov/SP-404/ch4.htm

geometry of post-perihelion observation of Comet Kohoutek; C.A. Lundquist, Skylab’s Astronomy and Space Sciences (1979), Figure 4-9, page 49: "Work of the US Gov. Public Use Permitted," via NASA History @ https://history.nasa.gov/SP-404/ch4.htm

For further information:

Bell, Edwin, II, cur. “Ultraviolet Stellar Astronomy: NSSDCA ID: 1973-027A-02.” NASA GSFC Space Science Data Coordinated Archive (NSSDCA) > NSSDCA Master Catalog (NMC) > Experiment Query.
Available @ https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-027A-02

Gary, Gilmer Allen, ed. Comet Kohoutek: A Workshop Held at Marshall Space Flight Center Huntsville, Alabama June 13-14, 1974. Washington DC: National Aeronautics and Space Administration, 1975.
Available via Internet Archive @ https://archive.org/details/CometKohoutek

Hitt, David; Owen Garriott; and Joe Kerwin. Homesteading Space: The Skylab Story. Featuring the In-Flight Diary of Alan Bean. Lincoln NE: University of Nebraska Press, 2008.
Available via Google Books @ https://books.google.com/books/about/Homesteading_Space.html?id=sR5Cm_zeIekC

Lundquist, Charles A., ed. “Appendix: Skylab’s Astronomy and Space Science Experiments.” Skylab’s Astronomy and Space Sciences: 116-117. NASA SP-404. Washington DC: National Aeronautics and Space Administration Scientific and Technical Information Office, 1979
Available @ https://history.nasa.gov/SP-404/appendix.htm

Lundquist, Charles A., ed. “Chapter 4: Observations of Comet Kohoutek.” Skylab’s Astronomy and Space Sciences: 42-63. NASA SP-404. Washington DC: National Aeronautics and Space Administration Scientific and Technical Information Office, 1979.
Available @ https://history.nasa.gov/SP-404/ch4.htm

Marriner, Derdriu. “Arabella and Anita Spun First Space Webs in August 1973 at Skylab.” Earth and Space News. Wednesday, July 31, 2013.
Available @ https://earth-and-space-news.blogspot.com/2013/07/arabella-and-anita-spun-first-space.html

Marriner, Derdriu. “Edward Gibson Sketched Comet Kohoutek’s Changes During Close Approach.” Earth and Space News. Wednesday, Jan. 15, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/01/edward-gibson-sketched-comet-kohouteks.html

NASA George C. Marshall Space Flight Center. MSFC Skylab Kohoutek Project Report. NASA Technical Memorandum TM X-64880. Huntsville AL: October 1974.
Available via Internet Archive @ https://archive.org/details/NASA_NTRS_Archive_19740027130
Available via NASA Technical Reports Server (NASA NTRS) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740027130.pdf

Shayler, David J.; and Colin Burgess. NASA’s Scientist-Astronauts. Springer-Praxis Books in Space Exploration. Chichester UK: Praxis Publishing Limited, 2007.