Are we alone? Scientists seek answers

Scientists are finding water in unlikely places throughout the solar system. Image: Illustration.
Scientists are finding water in unlikely places throughout the solar system. Image: Illustration.

       By the time today's third-graders reach college, we will have evidence of life forms on other planets, scientists believe.

      And by the time those same third graders are in their 30s or 40s, there will be definitive proof, according to NASA’s chief scientist, who spoke during a televised conference April 7.
     “I think we’re going to have strong indications of life beyond Earth within a decade,” said Ellen Stofan, NASA’s chief scientist, speaking at the televised forum. “And I think we’re going to have definitive evidence within 20 to 30 years. We know where to look. We know how to look. In most cases we have the technology. We’re on the path to implementing it.”
      Mankind may soon know the answer to that age-old question: Are we alone? But this is not necessarily about little green men. It’s about little microbes. Here are four takeaways from the conference on NASA’s search for water worlds.

    What is the significance of finding water on other planets?
     “The Earth formed 4.6 billion years ago. By about 3 billion years ago, life evolved here on Earth in the oceans,” Stofan said. “And for billions of years, it remained in the ocean. So that, certainly, is one of the things that really drives us to look for these watery worlds either in our own solar system or beyond our solar system.”

    If we're so focused on water, why are we interested in Mars?
    “About 50 percent of the northern hemisphere of Mars had water and it had it for a very long amount of time, perhaps more than a billion years,” said Jim Green, planetary science division director for NASA. “The current thinking is about 1.2 billion years.”

    How will scientists look for signs of life?
    NASA already has robotic spacecraft with sophisticated equipment on the red planet, Stofan noted. “We look for the building blocks of life. We look for organic molecules that might tell us that some process is going on. We look for something scientists call disequilibrium. We look for things out of balance. Is there something that seems to be consuming something and giving something else off?”
    But finding the smoking gun can be difficult. “I have a bias that it is eventually going to take humans on the surface of Mars – field geologists, astrobiologists, chemists – actually out there looking for that good evidence of life that we can bring back to Earth for all the scientists to argue about.”

     Scientists often talk about looking for planets in the habitable zone, but is the definition of a habitable zone changing?
     Basically, when scientists talk about the habitable zone, they mean the distance from a star in which the temperature of an orbiting planet might be suitable for water. In planets far from the sun, water should be found only in the solid form -- at least, that used to be the thinking. 
     Hubble space telescope observations show potential “plumes of material, water, ice, flowing from cracks perhaps in Europa (one of Jupiter's moons) from the southern hemisphere,” Green said.  
     “We now we recognize that habitable zones aren’t just around stars, but they can indeed be around our giant planets,” Green said.  “What we’re finding out is that the solar system is really a soggy place.”


      Mars In Brief: More evidence of habitable environment as rover chugs onward

      Water detected on dwarf planet

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