The Notion of Life on Mars

 From Scientific American:

One of the most intriguing aspects of the history of the human quest to discover whether or not there is other life in the universe, and whether any of it is recognizably intelligent in the way that we are, is just how much our philosophical mood has changed back and forth across the centuries.

Today we’re witnessing a bit of a "golden age" in terms of active work towards answers. Much of that work stems from the overlapping revolutions in exoplanetary science and solar system exploration, and our ongoing revelations about the sheer diversity and tenacity of life here on Earth. Together these areas of study have given us places to look, phenomena to look for, and increased confidence that we’re quick approaching the point where our technical prowess may cross the necessary threshold for finding some answers about life elsewhere.

Into that mix goes the search for extraterrestrial intelligence (SETI); as we’ve become more comfortable with the notion that the technological restructuring and repurposing of matter is something we can, and should, be actively looking for. If for no other reason than our own repurposing of matter, here on Earth, has become ever more vivid and fraught, and therefore critical to appreciate and modify in aid of long-term survival. But this search, labeled as both SETI and the quest for “technosignatures”, still faces some daunting challenges – not least the catch-up required after decades of receiving a less-than-stellar allocation of scientific resources. (Read more.)

 

From Fishwrap:

The popularization of the idea of canals on Mars began with the observations of a 19^th-century Italian astronomer named Giovanni Schiaparelli. Schiaparelli believed he saw a system of straight lines on the surface of Mars, which he called “canali” in 1877. Although the Italian word can be translated to mean “channels”—which is closer to what Schiaparelli intended—the word got translated in to English as “canals.” A wealthy American astronomer named Percival Lowell then performed his own observations of Mars and saw the same type of lines that Schiaparelli saw. But Lowell went one step further than his Italian counterpart. Lowell concluded that if there were “canals” on Mars, they must have been constructed, which in turn meant there must be intelligent beings on the planet who built them.

In the 1890s, Lowell funded the building of the Lowell Observatory in Flagstaff, Arizona, as a base for his intensive observations of Mars. He would remain convinced of the existence of artificially constructed canals on Mars for the rest of his life, even speaking about it a month before his death in 1916. (Read more.)

 

From Wired:

Subsequent mapping of the surface of Mars of course found no such canals, and thankfully none of NASA’s rovers have yet tumbled into the greatest public works project the solar system has (n)ever known. We now know, though, that water likely flowed freely on Mars long ago, but today is almost exclusively locked in the polar caps, with liquid water perhaps flowing from time to time.

Lowell was wrong, sure, really wrong, but his study of the Martian surface and the consequent debate most certainly advanced our understanding of the Red Planet. And his observatory? In 1930, Clyde William Tombaugh peered through its telescope and discovered the planet Pluto, whose existence Lowell himself had predicted.

So yeah, alright, they were maybe wrong about it being a planet. It’s really a dwarf planet and Kuiper-belt object. But we only decided that a few years ago (after much debate among astronomers – some folks in fact vehemently demand it immediately regain its erstwhile title, particularly these third-graders). It’s all just semantics, really. (Read more.)

From Space:

Alas, the universe is not that simple, at least according to new research recently appearing in the preprint journal arXiv. Using a suite of computer simulations to recreate atmospheric conditions on exoplanets, or planets outside of our solar system, the researchers behind the paper studied a plethora of potentially habitable systems. They changed the size and type of the planets' parent stars, the characteristics of their planetary orbits, the amount of liquid water already available to the planets when they formed and, most importantly, their atmospheres.

Researchers have previously studied the impact of a planet's atmosphere on its climate. The most notable gas is, of course, carbon dioxide, which is a greenhouse gas that has garnered quite a bit of attention here on Earth as it's a leading driver in climate change. Greenhouse gases are capable of trapping heat within a planetary atmosphere, and by changing that just a little, you can drastically alter the temperature history of an entire world.

For example, consider our sister planet Venus, which also sits within the habitable zone of the sun. However, thanks to an overload of carbon dioxide in its distant past, it experienced a runaway greenhouse event and now has the hottest surface temperatures of any planet in the solar system. And it's most definitely not habitable.

But carbon dioxide isn't the only gas to float around planetary atmospheres. There's also nitrogen. Nitrogen is pretty much inert and doesn't participate in many active biological processes. Yet, it makes up over 80% of Earth's atmosphere, and without it, we … well … wouldn't have an atmosphere.

We know very little about the history of nitrogen on Earth. We're not sure how much of the gas our planet was born with, and some geologic evidence even indicates that, as recently as 2 billion years ago, we had as little as half the nitrogen we do today. And, since we don't know much about nitrogen on Earth, we certainly don't know much about nitrogen on other planets. (Read more.)

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