New Locations for Life

What other planets and moons are habitable? What kinds of stars support habitable planets? What about moons?

Scientists’ answers to these questions are shifting. Partly, this is due to what’s been learned about extremophiles, organisms found on earth that can survive “scalding waters, subzero temperatures, bone-crushing pressures, corrosive acid, extreme salt and arid conditions…(and) withstand massive doses of radiation, breath rust, eat sulfur, belch methane and live without oxygen or sunlight.”

extremophiles.jpg“Finding extremophiles on Earth has just been mind-blowing,” said Carol Tang, a researcher from the California Academy of Sciences who studies extremophiles. “If you think about how there’s very few places on Earth where there isn’t life, you can’t think about the solar system and the universe in a very limited way anymore.”

(Ever-politically correct, Wikipedia hastens to point out that “the definition of ‘extreme’ in this context is anthropocentric; from the point of view of the organism, its environment is completely normal.” Yeah, we don’t want to insult the one-cell community!)

Scientists from the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, CA, are entertaining a debate about whether there is a chance for intelligent life to exist on planets that circle around the dimmer red dwarf stars that comprise 85 percent of all stars. It’s a resource question for SETI; they’re going to soon deploy its Allen radio telescope array to try to pick up radio signals from intelligent extraterrestrial life. They need to decide if the red dwarfs are worth listening to.

One of the main objections was that the habitable zones of red dwarfs would be very narrow and very close to the stars. For a planet orbiting a red dwarf to be warm enough to have liquid water, it would need to be located closer to the star than Mercury is to our own Sun. At such a close distance, the planet would become tidally locked to the red dwarf the way our Moon is to Earth. Any water existing on such a planet would be boiled away on the side facing the star and frozen solid on the other.

In recent years, however, new computer models have suggested that the situation isn’t as impossible as it might seem. The models predict that if an orbiting planet had a thick enough atmosphere, heat could be redistributed from the lit side of the planet to the side that was dark.

red dwarf.jpgAs for the criticism that a red dwarf’s habitable zone is very narrow, Todd Henry, an astronomer at Georgia State University, has an interesting view. Because there are so many more red dwarfs than stars like our Sun, Henry has performed calculations suggesting that if the narrow habitable zones of all the red dwarfs in our galaxy were combined, they would equal the habitable zone of the all the Milky Way’s Sun-like stars.

Jupiter’s moon Europa presents another possibility — a moon far away from the sun, but with an internal heat source that keeps some of its waters in a fluid state.

Scientists think Europa stays warm by a process called tidal heating. All moons, including our own, are stretched and pulled by the planet they orbit. Jupiter is so massive and its gravity so strong that it actually causes Europa’s surface to bulge and shrink as it circles around in its orbit. This constant motion generates friction and heat.

Saturn’s cloud-covered moon, Titan, is thought to be warmed by the same process. Other moons generate heat through different means. Scientists recently discovered that Saturn’s moon Enceladus, for example, contains a mysterious hot spot in its southern hemisphere that might be caused by radioactive material left over from the moon’s formation billions of years ago.

Allen Telescope Array.jpgThis is not to say that Europa, Titan or Enceladus have intelligent life. But the existence of such processes in our solar system greatly increase the number of possible configurations that could hypothetically support life, even intelligent life, in the Universe.

2 thoughts on “New Locations for Life

  1. Well, this is particularly interesting to me because . . . I’ve finally gotten into the new Sci-Fi Channel remake of the Battlestar Galactica series. You know the basic plot from the original campy 1970s series — Humans make machines called the “Cylons” to make their lives easier. The Cylons rebel and kick humanity’s collective arses, so the humans have to leave their planets to run away from the Cylons (who are in hot pursuit, in a maniacal effort to kill their creators). They are hunting for another inhabitable planet . . . the legendary planet “Earth.”

    The original series was fun, but sort of campy. The new version is intense, very serious, and one of the best things on TV. It stars Edward James Olmos, and it’s got the same gritty semi-military feel of the first two “Alien” movies. Obviously not as scary, but very real feeling. And unlike in the old version, the Cylons here have “evolved” and some look like humans — who have infiltrated the human fleet. And one of the Cylon “human” models is this sultry blonde sexpot who, via some data chip, is a continual hallucination of one of the main human characters and sometimes controls him. So, you’ve got this dimension of fear and distrust and insanity, as you don’t really know who might be a Cylon “sleeper,” or which human might be under the Cylons’ control. So, some of the themes we’ve been working out in the war on terror (I guess now called “The Long War”), including how to uncover sleeper cells or fifth columnists in our midst, are front and center in the show.

    You can rent the episodes — which I’ve been doing via Netflix. I’ve seen the pilot “miniseries” they ran initially, and then the first 4 episodes proper. Totally gripping television.

    So, absolutely — let’s keep looking for places we could inhabit. You never know when the Cylons will attack and force us to vacate!!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s