Both space enthusiasts and the general public alike are frequently enthralled by pictures of our home planet taken from space. Among the more impactful images of the Earth are those taken from far flung locations in the Solar System by humanity’s numerous robotic space explorers. NASA’s Mars Exploration Rover Spirit , which had landed inside Gusev crater on January 4, 2004, took the first image of the Earth from the surface of another planet during its 63rd Sol, or Martian day, on the Red Planet. Imaged an hour before local sunrise using the rover’s Pancam (Panoramic Camera), the Earth appears as a bright point of light in the eastern sky much as it would look to an astronaut standing on the Martian surface. But to find the first image of the Earth taken from the surface of another world, we have to go back another 37 years in history to NASA’s Surveyor 3 lunar landing mission.
This is the first image of the Earth taken from the surface of another planet. Acquired on Sol 63 of the mission of NASA’s Spirit Mars rover (March 9, 2004), it was taken using the rover’s Pancam about an hour before local sunrise. Click on image to enlarge. (NASA/JPL/Cornell/Texas A&M)
Launched on April 17, 1967, the 1,036-kilogram Surveyor 3 landed at 2.94° South, 23.34° West in Oceanus Procellarum at 00:04:16 GMT on April 20 to become NASA’s second successful lunar landing (see “Surveyor 3: Touching the Face of the Moon”). After bouncing three times before its engines were shut down by ground command, Surveyor 3 came to rest on the inner slope of an old 200-meter crater resulting in a noticeable 12° tilt to the local vertical. About 58 minutes after landing, Surveyor 3 returned its first images of the lunar surface beginning its lunar mission in earnest.
A view of Surveyor 3 on the lunar surface from November 20, 1969 during EVA 2 of the Apollo 12 mission. (NASA)
The vidicon-based, slow-scan television camera used by Surveyor 3 was mounted in a 1.65-meter-tall mast attached to the spacecraft’s framework. The camera pointed up into a movable mirror that allowed the camera to view 360° of azimuth and from 60° below to 50° above the normal plane of the camera. The 7.6-kilogram camera package was canted forward at a 16° angle to offer a clear view of the surface between the lander’s two of the footpads out to the lunar horizon 2½ kilometers away. The camera was fitted with a 25 to 100 mm zoom lens that offered a field of view of between 25.3° and 6.4°. The aperture could be set between f/4 and f/22 and the lens could be focused from 1.2 meters to infinity. A shutter was also included so that various integration times could be used to obtain the ideal exposure. While the nominal exposure time was 150 milliseconds, exposures as long as about thirty minutes could be accommodated for dim light imaging. The typical resolution of the camera was as good as one millimeter at a distance of four meters. By combining a series of images taken in a stepwise fashion at various azimuth and elevation angles, panoramic mosaics of the spacecraft and the surrounding terrain could be created.
Diagram showing the major components of the camera Surveyor used to image its surroundings after landing. Click on image to enlarge. (NASA)
The camera was also fitted with a filter wheel containing clear and three color filters. With the aid of calibration targets mounted at various points of the spacecraft, pictures taken through red, green, and blue spectral filters could be reconstructed back on Earth to yield full-color views of the lunar surface. The camera could only operate in real time via remote control from Earth using a total of 25 commands. The primary means of transmitting images was through the high-gain antenna. Using this powerful antenna, an image would be broken up into 600 scan lines and transmitted back to Earth in 3.6 seconds. The use of the less powerful low-gain antennas, which served as a backup, would permit an image to be broken up into 200 lines and would require 61.8 seconds to transmit.
A mosaic of Surveyor 3 television images taken on April 30, 1967 showing the landing site. Click on image to enlarge. (JPL/NASA)]
Near the end of Surveyor’s first lunar day on the surface, the mission’s science team had an opportunity to acquire the first images of the Earth taken from the surface of the Moon. The location of the Surveyor 3 landing site in combination with the lander’s tilt and a favorable libration of the Moon allowed the camera to catch a wide-angle glimpse of the Earth about 58° above the local horizontal to the east-northeast. At a distance of 381,400 kilometers, the resulting image scale was about 280-kilometers per scan line – comparable in resolution to a typical photograph of Mars of the era acquired using an Earth-based 20-centimeter telescope. Unfortunately, the Earth was just out of view when the camera was in its narrow-angle mode so taking higher resolution views was not possible.
This illustration shows the positions of the Earth’s features overlaid on a clear-filter image acquired by Surveyor 3 at about 10:36 GMT on April 30, 1967. (NASA/JPL)
From 10:29 to 11:06 GMT on April 30, 1967, Surveyor 3 was commanded to acquire a total of 25 images of the Earth taken sequentially through clear, red, green, and blue filters. The camera was pointed at an azimuth of 312° and an elevation of 36.3°, with respect to the spacecraft’s coordinate system, with the iris set to f/5.2 for the color filtered images and f/14.7 for the brighter, clear filter image. Three of the color filtered images were subsequently selected for processing and conversion into a true color photograph of the Earth. Centered roughly on South America, the resulting view from Surveyor 3 showed a cloud-covered crescent with a breaks in the clouds revealing the Caribbean Sea and southwestern Brazil. Analysis showed the clouds to be white with other areas ranging from greenish blue to purplish blue in color – similar to the colors observed by astronauts during the Mercury and Gemini missions.
Here is a true color image of the Earth as it appeared from the surface of the Moon at about 10:38 GMT on April 30, 1967. (NASA/JPL)
Ground controllers placed Surveyor 3 into hibernation on May 1 after the Sun had set but, unlike the other Surveyor landers, it could not be revived after sunrise for a second lunar day of operations as part of an extended mission. The story of Surveyor 3 would have ended there were it not for the decision to use the long-silent spacecraft as a target to demonstrate a precision landing for the Apollo 12 crewed mission which arrived on November 19, 1969. During their second EVA on the lunar surface, NASA astronauts Charles “Pete” Conrad and Alan Bean visited Surveyor 3 perched inside what was dubbed “Surveyor Crater” and removed samples of the lander’s components to determine how 3½ years of exposure to the lunar environment had affected them. Among the items recovered was Surveyor’s camera which had taken that first image of the Earth from the surface of another world (see “The Apollo 12 Visit to Surveyor 3: A Preview of Space Archaeology“). The camera is now on display at the Smithsonian National Air & Space Museum.
The television camera recovered from Surveyor 3 undergoing its initial inspection in April 1970. (NASA)
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Related Posts
“Surveyor 3: Touching the Face of the Moon”, Drew Ex Machina, April 17, 2017 [Post]
“The Apollo 12 Visit to Surveyor 3: A Preview of Space Archaeology”, Drew Ex Machina, November 25, 2019 [Post]
References
Surveyor III: A Preliminary Report, NASA SP-146, June 1967
Surveyor III Mission Report Part III: Television Data, JPL Technical Report 32-1177, November 10, 1967