Mariner IV

The Mariner IV spacecraft was managed by scientists of NASA JPL. It captured the first images of another planet ever returned from deep space.

The photographs were “taken by a television camera that was nearly 150 million miles away, farther from Earth than any camera had ever traveled before. It was riding on Mariner IV, which, after an interplanetary journey of 7 1/2 months, flew within 9847 kilometers of Mars on July 15, 1965. It took more than 8 hours for the spacecraft to send across some 150 million miles the 240 000 bits that constituted each photograph. Mariner IV’s camera, its shutter automatically operating every 48 seconds as red and green filters were alternated before its lens, took a total of 21 complete pictures and a fraction of another.
These pictures provided man with his first chance since the invention of the telescope to view the surface of Mars without the hindrance of ‘straining to see through the Earth’s atmosphere like a driver peering through a rain-spattered windshield,’ as Dr. Robert Jastrow has expressed it” (Cortright, p. 130).

The images covered a discontinuous swath of Mars starting near 40° N, 170° E, down to about 35° S, 200° E, and then across to the terminator at 50° S, 255° E, representing about 1% of the planet’s surface.

The first photograph (left) shows three versions of photograph No. 1, the first photograph of Mars returned by the spacecraft; the raw version (lower left frame), the picture released with preliminary processing on July 15 (lower right frame) and the most recent intermediate step of data processing, including contrast enhancement factor of two and fiducial marks removed (top frame).
Photograph No. 11 was the best one taken by the probe, covering the Atlantis Basin between Mare Sirenum and Mare Cimmerium. The 96-mile diameter crater in the center was later named Mariner to honor the spacecraft.
The last two photographs (No. 21 and No. 22) were taken entirely beyond the terminator, with the last partial frame possibly beyond the dark limb of the planet.

“The historic value of these photos is clear. Their scientific value lies primarily in their indication of the existence of clouds and its demonstration of the importance and feasibility of imagery as a scientific tool for planetary exploration. Many scientists before that time had considered the surface of Mars to resemble more closely that of the Earth than that of the Moon. These pictures, portending a complete rearrangement of Mars on the family tree of the solar system, must be regarded as one of the high points of discovery of the space age, if not of the 20th century. Because of the speed with which photographic data can be disseminated, and the universal understanding of pictures, the entire world truly shared in the excitement of this discovery,” wrote Bruce Murray, of the California Institute of Technology (Cortright, p. 131).