THE SEARCH FOR LIFE ON MARS

A new account of the scientific quest that “promises to spring even more amazing surprises in the years to come.”

Journalists Howell and Booth, as well as most experts, agree that Martian life would likely resemble that on Earth, and earthly organisms are tough. They can thrive without oxygen or sunlight, at temperatures above boiling and below freezing, and in the presence of strong acids, toxic metals, and poisons. However, none exist without water. The good news is that Mars has water. The bad news is that its surface is bone dry. In the era before spacecraft, many observers believed in life on Mars, led by the brilliant, wealthy Percival Lowell (1855-1916), who built his own observatory, saw the iconic canals, and never doubted that they represented works of an advanced civilization. The general public—but few astronomers—agreed until the pioneering 1965 Mariner 4 flyby revealed a cratered moonlike surface, an atmosphere 1/100 thinner than ours, and a temperature of minus 150 degrees Fahrenheit. The authors deliver a densely detailed account of subsequent unmanned flybys, orbiters, and landers whose missions have returned an avalanche of new geological, chemical, and meteorological discoveries that thrill scientists but may overwhelm general readers. Two more landers should launch soon, and much is expected. The authors conclude that most—but not all—experts consider Mars dead except, perhaps, deep underground, where liquid water may persist. A better environment existed billions of years ago, with volcanoes providing heat and gases, hot springs, and bodies of water that lasted perhaps 100 million years. “Conditions have deteriorated from earlier states into the freezing tundra-like world we see today,” write the authors, who provide the latest on the possibility of Martian life and proof that we probably won’t know for sure until humans set foot.

The search retains an irresistible fascination, and this enthusiastic account brings readers up to date.