An eye for an i #439 Children

The first spacecraft to orbit another planet

NASA's Mariner 9 spacecraft.   | Photo Credit: NASA/ Wikimedia Commons

The 20th-Century competition between the erstwhile Soviet Union and the U.S. to show greater spaceflight prowess is often dubbed the Space Race. While the race to the moon best captures our imagination, it neither marks the beginning nor the end of the battle between these two Cold War adversaries. The race to our neighbouring planet Mars took precedence once humans had set foot on the moon, and it even witnessed what one might consider a photo-finish on a cosmological scale.

Pairs for safety

During the initial stages of planetary exploration, it was customary for both these superpowers to launch pairs of spacecraft. The idea behind such an implementation was to ensure that one served as the backup for the other even if one of them failed in their objective completely.

In 1965, the U.S. enjoyed their first success with respect to Mars as Mariner 4 flew by Mars, capturing the first close-up images of the planet. Considering this success came hot on the heels of its twin Mariner 3’s failure, the idea of launching in pairs seemed a good one.

By 1969, NASA had furthered their accomplishments as Mariners 6 and 7 flew over Mars days within each other, with Mariner 7 even capturing an image of Phobos, one of Mars’ two natural satellites.

Need for orbiting

While these flybys were undoubtedly successful, long-term observations were necessary to better understand the planet. In order to achieve that, scientists turned their focus towards spacecraft that could orbit Mars, and thus document and measure various attributes of the planet.

With this objective in mind, NASA added more heft to Mariners 8 and 9 as they carried more instruments to help with the measurements and fuel to last the longer tenure of operations. Mariner 8 was launched on May 9, 1971, but the mission lasted just six minutes as a problem with a main engine meant that the spacecraft crashed in the water.

Race to the red planet

The second in the identical pair of spacecraft, Mariner 9 lifted off successfully from Cape Canaveral, Florida on May 30. But in the three weeks between the failure of Mariner 8 and success of Mariner 9, the Soviet Union had successfully launched a pair of their spacecraft – Mars 2 on May 19 and Mars 3 on May 28. The fight to become the first spacecraft to orbit Mars had literally become a race.

Despite starting a bit late, it was Mariner 9 that first reached Mars on November 14 after flying in space for 167 days. By igniting its main engine for 915.6 seconds, Mariner 9 put itself into orbit around Mars, thereby becoming the first human-made object to enter orbit around another planet. The orbital insertion of Mars 2 and Mars 3 was completed on November 27 and December 2 respectively.

Global dust storm

While the three spacecraft were ready to perform their next duties, Mars had other ideas. The planet was engulfed in a major global dust storm when these observers had arrived, obscuring everything but the peaks of the largest Martian features. It was only the images that were captured after the storm subsided that showed the red planet in spectacular detail.

Even though Mars 2 and Mars 3 were able to send only a minimal number of usable images, Mariner 9 did exceptionally well. It was able to identify about 20 volcanoes by February 1972, including what was later named Olympus Mons, which stands at over 21 km height. It also identified another major surface – a system of canyons that is more than 4,000 km long and 200 km wide. The canyon was named Valles Marineris in honour of Mariner 9, its spacecraft discoverer.

Grand success

NASA declared that Mariner 9 had achieved all its objectives on February 11, 1972, but the spacecraft continued to send back useful information. Having set out with the primary mission of mapping 70% of the Martian surface, Mariner 9 far exceeded it.

By the time of last contact on October 27, 1972, Mariner 9 had returned 54 billion bits of scientific data, including over 7,300 photos, some of which were that of Mars’ moons Phobos and Deimos. These images mapped 85% of Mars’ surface at a resolution of 1-2 km. The huge success of Mariner 9 paved the way for the landers that have made their way to Mars since then.


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Printable version | Sep 28, 2021 3:50:25 PM | https://www.thehindu.com/children/the-first-spacecraft-to-orbit-another-planet/article34614297.ece

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