As we count down to the much-anticipated landing of NASA’s six-wheeled Mars Science Lab (MSL) on Aug. 5/6th, it’s noteworthy that 36 years ago today mankind made the first successful touchdown on the Red Planet.
The nuclear-powered Viking 1 lander settled down in a burst of retrorocket fire on a smooth circular plain close to the great volcanic Tharsis Bulge on July 20, 1976. Four billion years ago this region may have been a water-filled bay on Mars.
Viking’s first black-and-white image (above) of a footpad resting on an alien planet transfixed the world.
Viking 1 was shutdown in 1982, but its legacy is as alive as ever today. Viking 1, and its sister robot, Viking 2, were the only two spacecraft ever dispatched to Mars with miniature onboard biological laboratories that performed the first in-situ experiments to find extraterrestrial life.
Though sending such a payload to what was then a largely unknown planet seemed premature, it does reflect NASA’s aggressive spirit of exploration from the glory days of the 1960s and early 70s.
One out of three independent miniature experiment labs aboard the Vikings yielded positive results, as established by the rules of its builders.
The Viking lab measured a rapid increase in oxygen, carbon dioxide and some nitrogen when a soil sample was saturated with liquid nutrients that astrobiologists thought would be tasty to Mars microbes. The out-gassing from the damp soil was like an Alka Seltzer tablet bubbling away. This reaction did not happen in samples that were sterilized by heat as a control. The second Viking lander recorded similar results 4,000 miles away.
However, the findings were dismissed almost immediately because no organic compounds were detected on the Martian surface by another Viking instrument. The building blocks of life as we know it apparently weren’t there. It was like hearing music, but not finding the orchestra.
The apparent false positive in the Labeled Release experiment was attributed to peculiar properties of the Martian soil. Hydrogen peroxide in combination with other chemicals in the Martian surface had been theorized to produce false life signals. But lab experiments on Earth have never precisely duplicated the Viking data. …
The Viking debate aside, we’ve learned a lot more about Mars since 1976. With each mission the circumstantial evidence for life has ratcheted up. Today we know that Mars has the energy, water and the chemical resources for supporting life.
Mounting geologic evidence points to Mars starting out as a habitable planet. But it grew colder and drier as its water froze, much of the atmosphere was ablated away by the solar wind, and a protective magnetic field fizzled away. Darwinian evolution should have ensured that primeval life, perhaps spawned in a great polar ocean, would find innovative ways to adapt and survive on a slowly dying world. ….