OUR SPACE: Mariner 4 turns 60

Published 9:57 pm Sunday, July 20, 2025

Let’s face it: Mars is everybody’s favorite planet (at least in this solar system). People have been fascinated by the Red Planet since ancient times, and as far as our planetary neighbors are concerned it’s also the one most easily explored — relatively speaking. Now this doesn’t mean it’s easy to go there; in fact, Mars missions in general have a shockingly high failure rate. But surface exploration is actually feasible, unlike hellishly hot Venus or tiny Mercury with its permanently hot and freezing cold sides. Of all the rocky planets in the solar system Mars is the most Earth-like, and we’re currently looking at how similar the two planets’ early history was, until something went very wrong with Mars, as we explored in earlier columns.

After thousands of years of wondering what Mars was like, early telescopic observations led to some pretty outrageous claims — you’ve probably heard of the supposed “canals” on Mars, the result of underpowered optical instruments and human imagination gone wild. All of this speculation of possible civilizations on Mars came to an end when Mariner 4 took the first close-up photos of this mysterious world.

Sixty years ago this week the Mariner 4 space probe was the first human-made object to do a close flyby of Mars. It took pictures which were relayed back to Earth and finally put all the stories about Little Green Men to rest: Mars was shown to be a desert-like planet without any obvious signs of life. It did, however, discover a thin atmosphere. It was the first time a spacecraft had ever taken photos of another planet from deep space!

The Mariner series of spacecraft explored the inner solar system from the early 60s to the early 70s and racked up an impressive lineup of “Firsts”, doing flybys or orbiting Mercury, Venus and Mars. Flybys were big news back then and an efficient way of getting good data without the added complications and vastly bigger fuel amounts required for an orbital mission — Mariner 9 did finally achieve the feat for Mars in late 1971.

Photography in outer space was a very different thing back then. In Mariner 4’s case a television camera system was used and the data was recorded on a small tape recorder (remember those?) and then sent back to Earth dot by dot. Scientists back home printed them out on ticker tape and lined all those strips up next to each other, using colored pencils to fill in the color codes until a completed picture emerged. And yes, one of those “paint by numbers” pictures still exists in the archives at JPL (Jet Propulsion Laboratory — Home Base of Yours Truly).

We don’t often think about how far photography in outer space has come in the past 60 years. We’re so spoiled by near-instant gratification, direct uploads to the internet and careful processing, which gives us the stunning images from the likes of Juno, Hubble, Webb or Chandra. Back in the day the smartest minds on the planet experimented with what was then cutting edge technology, hoping to get better and faster results with each mission. Recording data in critical situations and spooling it back to Earth at a leisurely pace later on is a method that has stood the test of time, and one that works particularly well during flyby encounters, so that all the spacecraft’s resources can be used for data acquisition in the heat of the moment. Most current missions with flybys still use this system – and it works just fine, even if it means waiting a little bit longer. The results are always worth the extra wait!

Surface missions like rovers generally rely on relay stations in orbit to send the data back to Earth rather than sending everything the direct route. It’s way more energy efficient for a small rover to upload stuff to an orbiter while it crosses overhead, and let the orbiter zap everything to the Deep Space Network (DSN) back on Earth. Since the DSN always has an antenna pointing in each direction the only thing that needs to be worked out is priority downloads. And since we have several rovers and orbiters on and around Mars, the data stream can be bundled and combined.

Mariner 4 was supposed to last about eight months, but it actually remained in a solar orbit for over three years, continuing its mission by measuring the solar wind and doing tandem measurements with Mariner 5 which headed to Venus a few years later.

A treasure trove of Mariner 4 information and other early planetary explorers can be found at https://science.nasa.gov/mission/mariner-4/ — and yes, there is a photo of the first digital image of Mars, hand-colored and carefully preserved and mounted in a large wooden frame. Check it out!

—Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at  our_space2@yahoo.com .