On August 6, 2012, the latest in a long series of exploratory spacecraft will approach the planet Mars at high speed. Slicing into the upper atmosphere, it will unfurl a large parachute, and, when it has slowed sufficiently, eight rocket motors will fire to stop its descent just above the surface of the planet. As the craft hovers, insect-like, a series of winches and cables called Skycrane will lower its payload to a soft landing on the floor of Gale Crater. If all goes well, the Mars Science Laboratory, a robotic rover the size of a Mini Cooper, will begin a long and productive journey of discovery on the Red Planet.
In recent decades, such missions to Mars have become almost routine. Every few years NASA announces the arrival of another one, followed by a series of stunning photographs and press releases describing new evidence for water on the Martian surface. Ho-hum? Science journalist Rod Pyle’s lively overview of Mars missions should be an antidote to any such ennui. It traces the slow evolution of our knowledge about Mars through almost a half century of nail-biting successes and failures, highlighting the remarkable advances in technology and science that have made visits to the planet seem so mundane.
Operating a spacecraft on the Martian surface, notes Pyle, is “a bit like doing brain surgery through a mile-long soda straw.” Two-way radio communication can take up to to forty minutes (when Mars is at its most distant from Earth), so that any action has to be carefully planned to avoid sending erroneous instructions that could jam a delicate moving part or send a robotic rover into a ditch. Even the odds for safe arrival aren’t that good: of nearly forty spacecraft that have set forth for Mars since the 1960s, only nineteen have arrived in operating condition. NASA’s score is thirteen out of twenty. Many, especially early Soviet spacecraft, failed at launch, but there were several particularly heartbreaking and embarrassing losses at the other end of the trip. NASA’s 1998 Mars Climate Orbiter memorably crashed into Mars because a segment of mission-control software erroneously used British Imperial units instead of metric units.
But over the years, NASA has scored inspiring successes. The two Viking missions of 1976 soft-landed instrument packages to test for the presence of extraterrestrial life. The 2004 Mars rovers Spirit and Opportunity, originally designed to operate for ninety days, won the hearts of the Web-watching public when they robo-posted images for years. Spirit went silent after six years of exploration, but Opportunity continues to trundle around and, as I write, is exploring the rim of the large crater Endeavor.
As a result of these efforts, Mars—once little more than a smudge through the best telescopes—has become a world whose rich and varied geological history is known in increasingly greater detail. The few fuzzy photographs sent back by the first flyby, Mariner 4, in 1965, have now been joined by tens of thousands of photographs.
Pyle’s conversational style is ideal for conveying the excitement of these decades of discovery. He draws heavily on interviews with the engineers and scientists who have worked on these missions, especially at the Jet Propulsion Laboratory in Pasadena. “I’m a lucky man,” one remarks; “lucky to be able to work with some of the best scientists and engineers in the world. Together we accomplish great deeds.” Read about these great deeds in Pyle’s book, and appreciate them with renewed interest this August, when the Mars Science Laboratory touches down in Gale Crater.