Cape Canaveral, Florida (JFK+50) The unmanned "Viking I" spacecraft was launched successfully from here at the Cape forty years ago today, August 20, 1975. The destination was the planet Mars*.
According to NASA, a second spacecraft, also unmanned, "Viking II" was launched within two weeks. Each consisted of both an orbiter and lander.
Viking I entered an orbit around Mars on June 19, 1976 and landed on the surface of the Red Planet the following day. Both orbiters of the Viking mission took photographs of the surface from which landing sites were selected for the landers.
The Viking landers took full 360 degree pictures, collected and analyzed soil samples, and also monitored surface temperatures, wind direction and speed.
NASA says that "the results...revolutionized our view of Mars."
According to www.space.com, Mars made its' "closest approach to Earth in...60,000 years," at 34,647,420 miles. It was then photographed by the Hubble Space Telescope.
*Mars is a cold desert planet with the same amount of dry land as Earth but half the diameter. It is 140 million miles from Earth, has seasons, polar ice caps, volcanoes, canyons and weather, but an atmosphere to thin for liquid water to exist for long periods and thus not supportable for life as we know it.
Mars is known as the "Red Planet" because of iron minerals in its soil which oxidize and make it look red. It makes one orbit around the Sun every 687 Earth days.
"How Long Does It Take To Get To Mars?," by Nola Taylor Redd, February 13, 2014, www.space.com/
"Viking 1-2," NASA Science/Missions, www.science.nasa.gov/