Telescopic Tracking of Lunar Orbiter V Around the Moon

As a counterpoint to telescopic observations of the Apollo lunar missions, it turns out that there were earlier observations of spacecraft in lunar orbit. A series of five Lunar Orbiter photoreconnaissance satellites were launched in 1966-67, using converted Earth-satellite systems to map the Moon. The primary mission was to certify potential Apollo landing sites near the lunar equator, a goal fulfilled by the first three missions so that the final two were put into polar orbits so as to map virtually the entire lunar surface. Lunar Orbiter IV was put into a high orbit (typically 3350 km above the surface), virtually completing the mapping mission, so mission V was put into a substantially lower orbit for high-resolution images of selected areas. Unusually for planetary missions in any era, all five Lunar Orbiters were successful.

The Lunar Orbiters were themselves responsible for some remarkable spectacular photographs - the first view of Earth above the stark lunar surface (I-101H2), a low-angle view of Copernicus ( 66-H-1470 or II-162H3) that brought home the extent of relief on the Moon, and the overhead view of the Mare Orientale impact basin ( IV-187M). Lunar Orbiter 3 also captured Surveyor 1 on the surface casting a long shadow (III-194H1). The 70mm film captured stunningly detailed images, to which a 0.5-m wide print can do justice if inspected with a magnifying glass (so these web versions are but pale impressions). A good overview of the program is given in [1].

At least one photograph exists showing a Lunar Orbiter as it circled the Moon. The image below was taken with the 1.5m telescope of Catalina Observatory (operated by the University of Arizona's Lunar and Planetary Laboratory). Steve Larson describes the observation as follows: "I participated in those observations with G. Kuiper, E. Whitaker and J. Fountain on 1968 January 21.5UT. To maximize our chances of recording the spacecraft so close to the bright moon, we had spent most of the night identifying all sources of scattered light in the telescope and masking them off with black paper and black tape. The moon was a day before last quarter, but Lunar Orbiter V was several minutes of arc off the bright limb when JPL commanded it to an attitude to generate a specular reflection off its solar panels towards our telescope. We captured several images of the spacecraft off the lunar limb, trailed even with a 10 sec exposure. My recollection was that it was estimated to be V~13, and it was heavily involved with scattered moonlight. Fortunately, the sky was clear and transparent."

It is fortunate that the image was released at the time with an enlarged inset showing the trailed spacecraft image; in this version, it doesn't stand out well even with the contrast is stretched on the main picture. The arrows indicate reference stars. Note that the success of this observation hinged on orienting the spacecraft to get a specular reflection of sunlight from its four flat solar panels toward the Earth, a trick that has been used more recently by NEAR-Shoemaker during a gravitational swingby of Earth.

Acknowledgements. Markus Mehring and Steve Larson have provided images and information for this page; without their contributions this corner of the Web would be vastly poorer.

For more information on the Lunar Orbiter spacecraft and photographic results:

  • The Moon as Viewed by Lunar Orbiter, L.J. Kosofsky and Farouk Al-Baz, NASA Special Publication SP-200, 1970. [1].
  • Lunar Orbiter Photographic Atlas of the Moon, David E. Bowler and J. Kenrick Hughes, NASA Special Publication SP-206, 1971. There is now a digital version.
  • NSSDC description of the Lunar Orbiter program
  • Destination Moon: A History of the Lunar Orbiter Program, Bryce Byers, NASA Technical Memorandum TM X-3487
    Bill Keel | UA Astronomy | Dept. of Physics and Astronomy | University of Alabama

    (ostentatious throat-clearing) "The views, opinions, and conclusions expressed in this page are those of the author and not necessarily those of The University of Alabama or its officers and trustees. The content of this page has not been reviewed or approved by The University of Alabama, and the author is solely responsible for its content. "
    Last changes: May 2004