April 09, 2020

Hope for evidence of life on Mars springs eternal

There must be life out there somewhere.

At least, people have always hoped so. To a medieval Christian, the stars were almost literally heaven itself, where life is eternal. Then in the 1610s, Galileo turned a telescope on the sky, and the hope for life beyond Earth was transformed by science. The colors and lines in telescopes implied that planets were material rather than divine. This meant beings like us might be there, and the most tangible hope for them resided in nearby Mars. Even that hope has been made over.

The first maps of Mars’ surface were drawn in 1659. In the next hundred or so years, what seemed to be clouds were noticed, dark swatches appeared to be seas or vegetation, and polar caps seemed to expand and shrink, implying Mars had seasons. Around 1800 the astronomer William Herschel wrote that “the inhabitants [of Mars]… probably enjoy a situation similar to our own.”

More detailed maps were drawn, and by 1900 the American astronomer Percival Lowell proposed that the apparent networks of lines on Mars’ surface were canals carrying water from the poles to population centers. Debate about martian life raged.

Attempts to communicate with Mars by radio occurred fairly frequently. In 1924 a researcher convinced the U.S. military and Commerce Department to observe radio silence during two days of a close approach between Earth and Mars so he could listen for signals. When Orson Welles broadcast a radio adaptation of H.G. Wells’ “The War of the Worlds” in 1938, thousands of people, believing it was a news report of a martian invasion, panicked and rioted.

In the 1950s, Russian astronomers thought oddities in the orbit of Mars’ moon Phobos implied it was hollow, and therefore artificial. Carl Sagan made his first mark on American astronomy in the 1960s when he argued that fossils of ancient microbes might be strewn through the sands of Mars.

The hope for Martians survived even the Mariner 4 spacecraft’s pictures in 1965 of a rocky, dry, barren surface. In 1976, a Viking spacecraft landed and tested martian soil for signs of life. Scientists debated the results.

A strange episode began afterward when two imaging scientists noticed a photo taken by the Viking orbiter showing a land form that looked like a face. The more they computer-enhanced the images, the more the mile-long feature looked human. There appeared to be pyramids nearby. Was it evidence of an ancient martian civilization?

Some reputable scientists and academics thought the Face on Mars, as it was called, might be artificial. Others, including Sagan, went out of their way to ridicule the idea. In 1998 higher-resolution photos of the face suggested it was just a big, odd-looking rock mesa. In 2001 more pictures, and this year another, seemed to lay the Face on Mars controversy to rest. Some think the recent photos disprove nothing.

In 1996, some NASA researchers announced they had found fossils of martian microorganisms in a meteorite that was blasted from Mars 4 million years ago and fell to Earth in Antarctica. Other scientists were skeptical. In 1999 researchers said similar evidence was present on a much older meteorite that had been found in Egypt in 1911.

Meanwhile, data are accumulating that imply a lot of water is locked up in Mars’ surface. The main excitement about this: Water is the key ingredient for life. Hope springs eternal.


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