Apollo Telescope Mount

The ATM was actively cooled to maintain the temperature of the instruments within a certain range.{{Cite web|url=http://wwwsolar.nrl.navy.mil/skylab_atm.html|title=Apollo Telescope Mount|website=wwwsolar.nrl.navy.mil|access-date=2018-07-10|archive-url=https://web.archive.org/web/20171107060638/http://wwwsolar.nrl.navy.mil/skylab_atm.html|archive-date=2017-11-07|url-status=dead}} Pointing was done with the help of the Skylab computer, which could be commanded from the space station by astronauts or by communication link from Earth. The four external mounted solar panels deploy in an 'X' shape, and provide around 30% of the station's electrical power.

File:Skylab 2 Weitz at Apollo Telescope Mount control panel.jpg at the telescope's command and display (C&D) console inside Skylab during the mission (June 1973){{cite web |url=http://spaceflight.nasa.gov/gallery/images/skylab/skylab2/html/sl2-x9-747.html |title=Photo-sl2-x9-747 |website=spaceflight.nasa.gov |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20141228033737/http://spaceflight.nasa.gov/gallery/images/skylab/skylab2/html/sl2-x9-747.html |archive-date=28 December 2014 |url-status=dead}}]]

The ATM was one of the projects that came out of the late 1960s Apollo Applications Program, which studied a wide variety of ways to use the infrastructure developed for the Apollo program in the 1970s. Among these concepts were various extended-stay lunar missions, a permanent lunar base, long-duration space missions, a number of large observatories, and eventually the "wet workshop" space station.

In the case of the ATM, the initial idea was to mount the instrumentation in a deployable unit attached to the Service Module,{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770081341_1977081341.pdf |title=Archived copy |website=ntrs.nasa.gov |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20100518075300/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770081341_1977081341.pdf |archive-date=18 May 2010 |url-status=dead}} this was then changed to use a modified Apollo Lunar Module{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790073384_1979073384.pdf |title=Archived copy |website=ntrs.nasa.gov |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20100521102900/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790073384_1979073384.pdf |archive-date=21 May 2010 |url-status=dead}} to house controls, observation instruments and recording systems, while the lunar descent stage was replaced with a large solar telescope and solar panels to power it all. After launch, it would be met in orbit by a three-crew Apollo CSM who would operate it and retrieve data before returning to Earth. As many of the other concepts were dropped, eventually only the space station and ATM remained "on the books". The plans then changed to launch the ATM and have it connect to Skylab in orbit. Both spacecraft would then be operated by the Skylab crews.

With the cancellation of the later Apollo landing missions providing a Saturn V, the wet workshop concept was no longer needed. Instead, the plans were changed to orbit an expanded, dry version of the station. The ATM would now be launched attached to the station, as the Saturn V had enough power to launch them both at the same time. This change saved the Skylab program when a problem during launch destroyed one of the workshop solar panels and prevented the other from automatically deploying. The windmill-like arrays on the ATM, which fed power to both the ATM and the station, remained undamaged due to the protection within the launch shroud, and provided enough power for crewed operations until the one remaining workshop array could be deployed during the first crewed mission.

There were additional astronomical and Earth observation experiments aboard Skylab. During development, the ATM was subjected to thermal vacuum testing.[https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720011230.pdf APOLLO TELESCOPE MOUNT THERMAL SYSTEMS UNIT THERMAL VACUUM TEST ]

File:Deployment of Apollo Telescope Mount.jpg

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File:Skylab IV-view of telescope.jpg

There were 8 major solar studies instruments on the mount.{{cite web |url=http://mix.msfc.nasa.gov/abstracts.php?p=1320 |title=0101909 - H-Alpha #1 Telescope - Skylab Apollo Telescope Mount |website=Mix.msfc.nasa.gov |date=1973-01-01 |access-date=2016-02-27 |archive-url=https://web.archive.org/web/20150428225347/https://mix.msfc.nasa.gov/abstracts.php?p=1320 |archive-date=2015-04-28 |url-status=dead }}{{cite web|url=https://history.nasa.gov/SP-402/ch4.htm |title=ch4 |website=History.nasa.gov |date=1973-05-14 |access-date=2016-02-27}} Combined, they could observe the Sun in light wavelengths from 2 to 7000 Å (angstroms), which corresponds to soft X-ray, ultraviolet, and visible light.

• two X-ray telescopes
• extreme ultraviolet spectroheliograph
• ultraviolet spectroheliometer
• ultraviolet spectrograph
• visible light coronagraph
• two Hydrogen Alpha telescopes

Same instruments by designation:

The X-Ray instruments included:

• S-054
• S-056
• S-020 (X-ray and extreme ultraviolet camera)

UV instruments included:

• S-082A (Extreme ultraviolet spectroheliograph)
• S-082B (Ultraviolet spectroheliometer)
• S-055 (Ultraviolet spectrograph)

Hydrogen alpha and coronograph:

• H-alpha no. 1
• H-alpha no. 2
• S-052 (a Coronagraph)

Also, experiment S149 was attached to one of the ATM solar panels.{{cite web| url = https://www.nasa.gov/topics/history/features/skylab2.html| title = Owen Garriott Performs a Spacewalk During Skylab 3 {{!}} NASA| date = March 11, 2015}}

Six ATM experiments used film to record data, and over the course of the missions over 150,000 successful exposures were recorded.{{Cite web|url=https://history.nasa.gov/SP-402/ch4.htm|title=ch4|website=history.nasa.gov|access-date=2017-01-09}} The film canister had to be manually retrieved on crewed spacewalks to the instruments during the missions. The film canisters were returned to Earth aboard the Apollo capsules when each mission ended, and were among the heaviest items that had to be returned at the end of each mission.{{Cite web|url=https://history.nasa.gov/SP-402/ch4.htm|title=Ch4}} The heaviest canisters weighed 40 kg (88.1 lb) and could hold up to 16,000 frames of film.

Over the course of operations almost 30 canisters were loaded and utilized, and then returned to Earth.{{Cite web|url=https://history.nasa.gov/SP-402/ch4.htm|title=ch4|website=history.nasa.gov|access-date=2018-07-10}}

File:Solar eruption in 1973 seen by Skylab 2 (S73-33788).jpg|Solar eruption seen in this spectroheliograph covering the wavelength region from 150 to 650 angstroms (Skylab 2, June 10, 1973)

File:S74-15583skylabsunview.jpg|Extreme ultraviolet image of the Sun with the Earth added for scale (Skylab 3, July 1973)

File:Curving prominence red.jpg|A hiding, troutlike prominence is exposed when the blue coronal view is combined with a red-coded ultraviolet picture that samples cooler chromospheric temperatures. (Skylab 3, July 1973)

File:False Color Isophote of a Solar Eruption.jpg|False color image of a solar prominence (Skylab 3, August 21, 1973){{cite web |date=1973-08-21 |title=7461522 - A Solar Prominence Taken by the Skylab Telescope |url=http://mix.msfc.nasa.gov/abstracts.php?p=1375 |url-status=dead |archive-url=https://web.archive.org/web/20150428131459/https://mix.msfc.nasa.gov/abstracts.php?p=1375 |archive-date=2015-04-28 |access-date=2016-02-27 |website=Mix.msfc.nasa.gov}}

File:Solar prominence.jpg|Color processed ultraviolet image differentiating changes in a wispy prominence arch (Skylab 4, 14 December 1973)

File:Skylab ultraviolet view of a solar prominence (7461902).jpg|Ultraviolet image of a colossal eruption (Skylab 4, December 19, 1973).

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The instruments were used for various types of observations including pre-planned experiments, including a set of student experiments. This is a chart describing an example of this:

File:Skylab X-Ray Stellar Classes graphic (0102061).jpg |access-date=2022-04-16 |archive-url=https://web.archive.org/web/20220416064710/https://ntrs.nasa.gov/api/citations/20160013587/downloads/20160013587.pdf |archive-date=2022-04-16 |date=1973-03-01 |url-status=live}}]]

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File:Skylab X-ray Spectrographic Telescope (7022359).jpg

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A backup ATM spare (instruments were mounted to this) was restored and put on display in 2015 at the Steven F. Udvar-Hazy Center in Chantilly, Virginia, US.{{Cite news|url=https://airandspace.si.edu/stories/editorial/restoring-apollo-telescope-mount|title=Restoring the Apollo Telescope Mount|date=2015-12-10|work=National Air and Space Museum|access-date=2018-07-12|language=en}} The restoration involved repairing some Kapton layers that had degraded after 4 decades.

{{commons category|Apollo Telescope Mount}}

• Orbiting Solar Observatory
• List of X-ray space telescopes
• List of spacewalks and moonwalks 1965–1999 (in the early 1970s several Skylab spacewalks including servicing ATM)

{{Reflist}}

• [http://libarchstor.uah.edu:8081/repositories/2/resources/83 Apollo Telescope Mount, The University of Alabama in Huntsville Archives and Special Collections]

{{Project Skylab}}

{{Apollo program}}

{{Apollo program hardware}}

{{Space observatories}}

{{Sun spacecraft}}

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

Category:Apollo program hardware

Category:Skylab program

Category:Crewed space observatories

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Category:Ultraviolet telescopes

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Category:Solar space observatories