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Bob Berman’s Strange Universe: Another Earth: Where is the search leading?

May 2011: A huge disconnect exists between the actual science and the media hype.
bob_berman_2009
The hunt for exoplanets is “hot.” We see the idea of “another Earth” repeated almost daily on TV science shows. But where is the quest really taking us?
 
This astro-obsession resembles the “Canals on Mars” headlines a century ago. Naturally, it would be amazing if our world had a true analog somewhere. It’s a venerable sci-fi theme, where our twin planet has humans like us but with some freaky distinction. They all love liver and onions. Yet professional astronomers I speak with are bored by the whole “other Earth” media circus.
 
Why? Well, first, there are no surprises here. Statistically, there must be more than a million terrestrial-mass bodies in our galaxy’s comfort zones. A half-century ago, Peter Van de Kamp’s announcements of star wobbles, though later discredited, got us believing that stars have planets tugging at them. When we began detecting massive planets in the 1990s, few were surprised. We could only uncover big ones, and we duly spotted lots of them, some 500 so far. Then a few months ago, the Kepler team announced another 1,235 planet candidates, of which five dozen are Earth-sized.
 
In nature, minnows always outnumber whales. Our solar system contains five large objects and at least 368,000 small bodies. So from the get-go, those 500 confirmed giants mean Earths are as common as bed bugs. Newer methods now let us detect smaller objects, and, sure enough, Earth-mass planets have popped up. We’ll soon catalog hundreds, then thousands. There. Done.
 
Next, we’ll try to detect atmospheres. Oxygen is a biggie. It combines with almost anything, so normally there’s little free oxygen in a planet’s air unless some ongoing process pries it loose from its compounds. The most efficient mechanism for that is life. Earth’s air is 21 percent oxygen because plants absorb carbon dioxide, keep the carbon to grow their crunchy bodies, and release the oxygen. So detecting free oxygen around a planet would be evidence for life.

Possible life! Now there’s a headline. Except people would clamor for more news, and there wouldn’t be any. The best image of the planet would be a dot. Folks asking NASA to send a probe would learn that travel time is thousands of years. Knowledge about such planets would remain negligible.
Astronomers I speak
with are bored by the
whole “other Earth”
media circus.

When an intriguing discovery has a vast, long-lasting information gap, it often provokes fraud. Count on people claiming psychic communications or religious instruction from the “advanced civilization” on that “other Earth.” The gullible will have their Next Big Thing, now that the world didn’t end in 2012. I hate this already.

Anyway, we think life requires an Earth-mass planet because that’s where we live, and we’re not very imaginative. In reality, the most probable abode for exo-life is
the jovian moon Europa. Its mass doesn’t resemble ours (it’s more than 100 times lighter) nor is it located anywhere near the Sun’s habitable zone. What does this tell us about the reliability of our assumptions regarding E.T.’s whereabouts?
 
As for the cliché that finding life would be “the most amazing discovery ever” — well, don’t we already believe in life out there? Why would nature, with its penchant for abundance and adaptation, limit life to one planet? The clincher is the amino acids (life’s building blocks) we’ve detected in comets coming from distant places. Because we assume extraterrestrial life exists, finding it would scarcely knock us over or make us chant “Hare Krishna.” To the contrary, when NASA announced in 1996 that it had evidence for martian life in the meteorite ALH84001, no one on the street seemed to care at all.

People would pay attention to aliens that piqued our emotions, E.T.s resembling cuddly kittens or scary giant lobsters. But if moss were discovered 200 light-years away, how many would bother muting American Idol to phone their friends with the news?

The bottom line is a huge disconnect. Many laypeople find this research fascinating, but they have no realistic sense where it’s leading. They’re unaware that its endpoints will be inconclusive. They think “another Earth” means a world that truly resembles ours. The media fosters this fiction by using terms like “Goldilocks planet” when, in truth, no one knows whether any particular exoplanet has poisonous volcanic gases, high radiation, or any of dozens of other undetectable parameters that would ruin a planet’s habitability. Nor do they grasp the distances involved. Or the limits of what we can learn.

Pinpointing and listing the millions of planets that share our mass and crude temperature is valid science, like Robert G. Aitken’s double star catalog. But bombshell revelations? That’s media hype.

The Kepler mission team, Geoff Marcy’s crew, and other brilliant astro-sleuths will keep working, spurred by popular interest and the funding their work has unleashed. The media will cheer them on — for now. Historically, astronomical obsessions-du-jour last only a few years. Those teams had better hurry up and find those kittens.
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