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  1. Are We Alone? Where Are Our Nearest Neighbors?

    Excerpts from the written testimony submitted by Edward Weiler, Associate Administrator for Space Science, National Aeronautics and Space Administration, to the “Life in the Universe” hearings held by the House Subcommiteee on Space and Aeronautics on July 12, 2001.

    “There are countless suns and countless Earths all rotating around their suns in exactly the same way as the seven planets of our system. We see only the suns because they are the largest bodies and are luminous, but their planets remain invisible to us because they are smaller and non-luminous. The countless worlds in the universe are no worse and ...

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  1. Did Tectonis Get an Early Start?

    Based on a St. Louis University and Washington University in St. Louis press release

    A recent discovery near the Great Wall in China adds new support to the theory that plate tectonics began very early in the Earth’s history. The finding not only will help in understanding the geological processes of ancient Earth, but it could also provide some clues about the development of early life.

    It has long been known that plate tectonics – the motion of oceanic and continental plates – dates back at least 1.9 billion years. But Timothy Kusky, professor of geology at St. Louis ...

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  1. SETI and the Search for Life

    Excerpts from the written testimony submitted by Christopher F. Chyba, SETI Institute, to the “Life in the Universe” hearings held by the House Subcommitee on Space and Aeronautics on July 12, 2001.

    Over the past decade, there has been a rebirth in the scientific study of life elsewhere in the Universe – and for very good reasons. We’ve learned that organic molecules – the sort of carbon-based molecules all life on Earth is based upon – are abundant not only in our own solar system, but throughout the space between the stars. They are likely to be present in many ...

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  1. Starved for Nitrogen

    Based on a NASA Ames Research Center press release

    A team of researchers, including a NASA scientist, reports that an early-life nitrogen crisis may have triggered a critical evolutionary leap about 2 billion years ago.

    The team, from Universidad Nacional Autonoma de Mexico (UNAM) and NASA’s Ames Research Center in the heart of California’s Silicon Valley, published its results in the July 5 issue of the journal Nature. Their paper is entitled “A Possible Nitrogen Crisis for Archaean Life Due to Reduced Nitrogen Fixation by Lightning.” The researchers, who simulated early Earth atmospheric conditions in a laboratory, postulate ...

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  1. Happy Anniversary, Viking Lander

    Based on a Science @ NASA story by Dr. Tony Phillips

    Twenty-five years ago NASA’s Viking 1 lander made history by descending from orbit to the surface of Mars. It was the first probe from Earth to land intact on the Red Planet, and the first American spacecraft to land on any world since the Apollo program.

    Before Viking 1 touched down many people thought Mars might harbor abundant plant life and microbes living among the rust-colored rocks. Scientists guessed the skies might be tinged deep purple like Earth’s stratosphere, which is about as tenuous as the Martian atmosphere. But ...

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  1. The Search for Life in the Universe

    Excerpts from the written testimony submitted by Neil deGrasse Tyson, Department of Astrophysics & Hayden Planetarium, American Museum of Natural History, to the “Life in the Universe” hearings held by the House Subcommitee on Space and Aeronautics

    The discovery of what is now more than seventy planets around stars other than the Sun continues to stimulate tremendous public and media interest. It seems to me that this attention is driven not so much by the discovery of the extrasolar planets themselves, but by the prospect of intelligent alien life.

    People really care about whether or not we are alone in ...

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  1. NASA Picks Mars Scout Mission Ideas for Further Study

    Based on a NASA Headquarters press release

    NASA recently selected the ten most promising “Scout” mission concepts from among the 43 proposed for possible launch to Mars in 2007. The selected proposals will receive funding for six months of continued studies.

    Scout missions are innovative, relatively low-cost missions designed to further scientific knowledge of Mars in specific critical areas.

    Included in the ten concepts selected for study are missions to return samples of Martian atmospheric dust and gas, networks of small landers, orbiting constellations of small craft, and a rover that would attempt to establish absolute surface ages of rocks ...

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  1. Mars: Dead or Alive?

    “Mars ain’t the kind of place to raise the kids. In fact it’s cold as hell.” So goes the 1970s song by Elton John.

    The words expressed the public’s notions at the time about the Red Planet: dry, cold, dusty, barren and pockmarked by craters – the very images sent back by the Mariner series of spacecraft in the 1960s. Those same missions brought us pictures of the vast bulk of Olympus Mons, the largest volcano in the solar system. But while it loomed huge, it was apparently extinct. After examining these images, most scientists concluded that geologic activity ...

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  1. Water Worlds

    Based on a NASA Headquarters press release

    As an alien sun blazes through its death throes, it is apparently vaporizing a surrounding swarm of comets, releasing a huge cloud of water vapor. The discovery, reported in an article to be published tomorrow in the journal Nature, is the result of observations with the Submillimeter Wave Astronomy Satellite (SWAS), a small radio observatory NASA launched into space in December 1998.

    The new SWAS observations provide the first evidence that extra-solar planetary systems contain water, a molecule that is an essential ingredient for known forms of life.

    “Over the past two years ...

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  1. Life Down Under

    Based on a SETI Institute press release

    Recent work by Christopher Chyba (SETI Institute) and Kevin Hand (Stanford University) suggests that there may be ways to nourish biology in watery environments where the Sun’s rays don’t penetrate. The two researchers have published their work in the June 15 issue of the journal Science.

    “Most surface life on Earth – on land or in the seas – depends on photosynthesis,” notes Chyba. “The first link in the food chain is chlorophyll’s conversion of sunlight into chemically stored energy. But imagine an ocean on Europa, a huge, bottled-up body of water ...

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  1. How Small Can Life Be?

    As advanced microscopes enable us to peer deeper into the realms of inner space, biologists have been faced with a vexing question: Is there a size limit on life? If so, then just how small can something be before it can no longer be defined as “life”?

    Some scientists believe that life can be very small indeed. Called nanobes, nanobacteria, or nano-organisms, these miniscule structures borrow their name from their unit of measurement, the nanometer. A nanometer is one billionth of a meter. That’s about the length of 10 hydrogen atoms laid out side by side. The period at the ...

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  1. The Meaning of Life

    Sitting beneath a dark night sky, looking up at the vast array of stars, what human has not wondered, “Are we alone?”

    The possibility of life beyond Earth – particularly intelligent life – permeates popular culture. For the fearful, there are evil extraterrestrials intent on dominating and killing humans (“War of the Worlds,” “Alien,” “Independence Day”). For people inspired by hope and awe, there are wise, benevolent aliens (“Contact,” “E.T., the Extra-Terrestrial” and “Close Encounters of the Third Kind”).

    Turning to non-intelligent life, scientists by and large believe that if life is discovered on the ...

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  1. Europa: Chewy or Crunchy?

    For geophysicist William B. Moore, the question of whether life exists on Jupiter’s moon Europa boils down to whether the moon’s center is chewy or crunchy.

    Many scientists doubt life can exist on Europa’s surface because of extreme cold, lack of liquid water, the tenuous atmosphere and intense bombardment from Jupiter’s radiation belts.

    Moore believes distant Europa receives too little sunlight to provide the energy needed for organisms to thrive on its apparently icy surface. Others argue the chemical energy needed for life is created when charged particles bombard Europa to produce oxidants.

    Nevertheless, says Moore, Europa’s surface “would be ...

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  1. A Pregnancy Test for Mars

    The test that tells women they are pregnant might also be able to find signs of living organisms on Mars. Dave McKay at the Johnson Space Center and British environmental microbiologist Andrew Steele – both are members of the NASA Astrobiology Institute (NAI) – together with their collaborators, are eager to test the feasibility of this method for finding life’s footprints on the Red Planet.

    As presented by Steele and his colleagues at this year’s Lunar and Planetary Science Conference in Houston, the approach, which depends on the ability of the immune system to detect invaders, would involve a tiny ...

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  1. Do We Know What Killed the Dinosaurs?

    What killed the dinosaurs? Their sudden disappearance 65 million years ago, along with at least 50 percent of all species then living on Earth, is known as the K-T event (Cretaceous-Tertiary Mass Extinction event). Many geologists and paleontologists now think that a large asteroid or comet impacting the Earth must have caused a global catastrophe that led to this extensive loss of life.

    The Chicxulub crater in the Yucatan region of Mexico is a good candidate for the ancient point of impact. The crater is the right age – 65 million years old – and it is consistent with the ...

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