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Mars is in the news a lot these days. Movies about exploration of the planet are popular, and several space agencies around the world are planning human missions in the next decades. Yet, there was a time not so long ago in human history when NO mission had been to the Red Planet. That was in the early 1960s, when the Space Age was picking up momentujm.
Since then, scientists have been exploring the planet Mars with robotic spacecraft: mappers, landers, rovers, and orbiters such as Mars Curiousity, as well as the Hubble Space Telescope, which observes Mars from orbit around Earth. But, there had to be a first successful mission to get this all started.
Mars excitement began when Mariner 4 arrived at the Red Planet on July 15, 1965. It got as close as 9,846 km (6,118 miles) from the surface and returned the first good images of the cratered, dusty terrain. It was not the first mission launched to Mars, but it was the first successful one.
What Did Mariner 4 Show Us?
The Mariner 4 mission, which was the fourth in a series of planetary exploration missions, revealed the cratered, rust-colored surface of the planet. Astronomers knew Mars was red from years of ground-based observations. However, they were amazed at the color seen in the spacecraft's images. Even more surprising were pictures that showed regions showing evidence that liquid water had once etched its way across the surface. Yet, there was NO evidence of liquid water anywhere to be found.
In addition to various field and particle sensors and detectors, the Mariner 4 spacecraft had a television camera, which took 22 television pictures covering about 1% of the planet. Initially stored on a 4-track tape recorder, these pictures took four days to transmit to Earth.
Once past Mars, Mariner 4 orbited the Sun prior to returning to the vicinity of Earth in 1967. Engineers then decided to use the aging craft for a series of operational and telemetry tests to improve their knowledge of the technologies that would be needed for future interplanetary spacecraft.
All in all, the mission was a great success. Not only did it serve as a proof of concept for successful planetary exploration missions, but its 22 images also revealed Mars for what it really is: a dry, cold, dusty and apparently lifeless world.
Mariner 4 Was Designed For Planetary Exploration
NASA built the Mariner 4 mission to Mars to be tough enough to get to the planet and then study it with a set of instruments during its quick flyby. Then, it had to survive the trip back around the Sun and supply more data as it flew. Mariner 4's instruments and cameras had the following tasks:
- study interplanetary fields and particles, including the magnetic field of Mars, cosmic dust, cosmic rays, and the solar wind;
- take close-up images of Mars in hopes of discovering the geologic and atmospheric processes at work on the planet over the eons;
- provide experience in operating long-term interplanetary missions.
The spacecraft was powered by solar cells that provided about 300 watts of power for the ship's instruments and television camera. Nitrogen gas tanks supplied fuel for attitude control during flight and maneuvers. Sun and star trackers helped the spacecraft navigation systems. Since most stars were too dim, the trackers focused on the star Canopus.
Launch and Beyond
Mariner 4 rode to space aboard an Agena D rocket, launched from Cape Canaveral Air Force Station launch complex in Florida. Liftoff was flawless and a few minutes later, the thrusters fired to put the spacecraft into a parking orbit high above Earth. Then, about an hour later, a second burn sent the mission on its way to Mars.
After Mariner 4 was well under way to Mars, an experiment was approved to study the effect of transmitting the spacecraft's radio signal through the Martian atmosphere just before the spacecraft disappeared behind the planet. This experiment was designed to probe the thin blanket of air surrounding Mars. That task threw mission planners a real challenge: they had to reprogram the spacecraft's computer from Earth. That had never before been done, but it worked perfectly. In fact, it worked so well that mission controllers have used it many times with other spacecraft in the years since then.
Mariner 4 Stats
The mission was launched on November 28, 1964. It arrived at Mars on July 15, 1965 and performed all its mission activities well. Controllers lost communication with the mission from October 1, 1965 to 1967. Then contact was restored for a few months before it was lost again, for good. Throughout its entire mission, Mariner 4 returned more than 5.2 million bits of data, including imaging, engineering and other data.
Want to know more about Mars exploration? Check out "Eight Great Mars Books", and also keep an eye out for television specials about the Red Planet. It's a sure bet that there will be an increasing amount of press as humanity gets ready to send people to Mars.