• There are various cachets in this listing, including printed cachets by SPACECRAFT, SPACE VOYAGE, CENTENNIAL (unmarked), ORBIT (unmarked), and other unknowns. There are also rubber stamp cachets, label cachets, etc.
• All covers are unaddressed unless otherwise noted.
• The majority of the SPACECRAFT printed cacheted covers have a very tiny printed address at the right bottom of the envelope.
• The SPACECRAFT cachets listed here are the "Cadillac" of space cacheted covers that were issued from 1960 through 1975, drawn by artist Carl Swanson. They all are in two colors and depict the Mariner spacecraft and give details of the mission. Most of the SPACECRAFT cacheted covers have and additional descriptive filler card or paper insert with more details on the mission.
• All commemorative covers are for launches unless otherwise noted.

The two closest planetary neighbors of Earth are Venus and Mars and these were focused on for observation in the early days on man's exploration of our solar system.

The U.S. had a series of spacecraft or space probes called "Mariner". Mariner 1 and 2 were launched in 1962 to study Venus.

The first U.S. spacecraft launched for Mars exploration was on November 5, 1964. This mission, called Mariner 3, went into solar orbit as it had a shroud failure preventing it from flying by Mars.

Mariner 4 was launched a few weeks later on November 28, 1964 and was the first manmade spacecraft to pass within about 6,000 miles (9,700 kilometers) of Mars after a journey of 228 days.

On July 14, 1965, the Mariner 4 spacecraft rendezvoused with Mars and sent the first close-up photographs which showed with startling clarity that the surface of Mars closely resembled that on the Moon.

Other Mariner missions to Mars include Mariner 6, 7, 8, and 9 to further explore the red planet. The first U.S. spacecraft to land on Mars was a spacecraft called Viking 1 which occurred on July 20, 1976.

The U.S.S.R.'s first attempt to study Mars was in 1960 with two launches, both of which failed. The Russian's next attempts were in 1962 with three launches, one of which was called "MARS-1". These attempts also failed to achieve their goal of going to Mars. Their next Mars probe was not until 1971 and this started a series of additional Mars probes during the 1970s which included landing on the surface of Mars.

Check out my online lists which include the commemorate covers for the U.S.S.R. Mars missions: