1. Roses for the Red Planet

    It has been nearly 25 years since NASA sent biological experiments to Mars. Chris McKay, a planetary scientist with the Space Sciences Division of NASA’s Ames Research Center and a member of the NASA Astrobiology Institute, thinks it’s time to try again.

    McKay helped organize a NASA conference last year on what it might take to make Mars fit for human habitation. While the general tone of the conference was speculative—all of the participants agreed that humans aren’t likely to begin terraforming the Red Planet any time soon—McKay maintains that it was important nonetheless to begin now ...

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  1. Oily Fossils Provide Clues to the Evolution of Flowers

    Text based on a Stanford University press release

    Daffodils, tulips, roses and other flowers are so much a part of our daily lives that we take them for granted. Yet, how and when flowering plants appeared on Earth remains a mystery, a question that has gone unanswered by evolutionary scientists for more than a century.

    According to the fossil record, mosses were the first plants to emerge on land, some 425 million years ago, followed by ferns, firs, ginkgoes, conifers and several other varieties. Then, it seems, about 130 million years ago flowering plants abruptly appeared out of nowhere.

    Where ...

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  1. Focus on Europa

    Four decades of space exploration have taught us a great deal about the nine planets and dozens of moons that comprise our solar system. Yet Earth remains the only world on which we know for certain that life exists.

    Scientists and science fiction writers alike have long speculated on that Mars might also harbor life. But images of Jupiter’s moon Europa sent back by NASA’s Galileo spacecraft have led planetary geologists and biologists alike to seriously consider adding that ice-covered world to the list of possible habitats for life.

    Chris Chyba, who holds the Carl Sagan Chair for the ...

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  1. Twenty Thousand Leagues Under the Sea

    Miles below the ocean surface exist some of the most fascinating habitats for life on Earth. Here, where sunlight never reaches, live complex ecosystems that can appear and disappear within a matter of decades. What provides the thermal and chemical energy that fuels these ecosystems are deep-sea hydrothermal vents, one of the unofficial wonders of the natural world.

    These vents occur at oceanic “spreading centers,” mountainous ridges where magma from deep within the Earth’s crust forces its way up to the ocean floor, creating new ocean crust and pushing the old crust out of the way. This is ...

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  1. Life's Chemical Fingerprints

    Perhaps in 2008, a rover on Mars will press its robotic arm against a rock. A probe at the end of the arm will scan the rock, repeatedly zapping the surface with a microscopically thin laser beam, probably green or ultraviolet.

    As the laser light hits the rock, it will “scatter” (be deflected) in random directions. Most of that light will stay the same color, but a tiny fraction will be shifted just slightly to a different color, a phenomenon called the Raman effect. That slight shift will reveal whether the rock harbors the chemical signatures of life, either microbes ...

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  1. Return to the Red Planet

    The Mars Global Surveyor (MGS) currently orbiting Mars has sent back a wealth of new information. It has revealed an enticing sample of the martian surface at a level of detail never previously achieved from orbit. It has shown us layered sedimentary deposits in crater basins. It has discovered what appear to be seepage gullies caused by recently running water, in regions of Mars believed to be far too cold for liquid water to flow.

    As is often the case, these discoveries have led to new questions. For example, if there are so many places where the martian landscape appears ...

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  1. Taking the Temperature of a Martian Meteorite

    Inside martian meteorite ALH84001 may lie the fossilized remains of ancient bacteria. Some scientists have suggested that other martian meteorites could have seeded the early Earth with primitive forms of life. Others argue that any asteroid or comet that impacted Mars with sufficient force to eject material into interplanetary space would have superheated the ejecta, and that bacteria could not have survived.

    New research by Benjamin Weiss and his colleagues at the California Institute of Technology indicates that at least one such meteorite — ALH84001 — didn’t get all that hot. Weiss’s team believes that the interior of ...

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  1. Can Liquid Water Exist on Present-Day Mars?

    In 1998, NASA’s Associate Administrator Wesley Huntress, Jr., stated, “Wherever liquid water and chemical energy are found, there is life. There is no exception.”

    Could there, then, be life on Mars? In the mid-1970s, the Viking Lander mission’s Gas Exchange Experiment detected strong chemical activity in the martian soil. Liquid water seems to be the one element needed for the equation of life on Mars. The presence of water there, however, is still hotly contested.

    Many scientists believe that liquid water does not and cannot exist on the surface of Mars today. Although surface water may have been ...

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  1. NASA Astrobiology Institute Announces New Teams

    Text based on a NASA Ames Press Release

    NASA has selected four new teams to become part of the agency’s Astrobiology Institute (NAI), a national and international research consortium that studies the origin, evolution, distribution and future of life on Earth and in the universe.

    After a highly competitive peer-review process, teams from Michigan State University (MSU), East Lansing; the University of Rhode Island (URI), Kingston; the University of Washington (UW), Seattle; and NASA’s Jet Propulsion Laboratory (JPL), Pasadena, CA, today were notified of their selection.

    These new teams of researchers will bring specialized expertise to the institute, allowing ...

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  1. Evo Devo Learns a Larval Lesson

    In Ridley Scott’s 1979 slimy monster masterpiece, “Alien,” the extraterrestrial life form discovered by Sigourney Weaver and crew goes through two startlingly different phases after it hatches. Is such a change during the life of an animal mere SciFi license? Not really. In fact, many earthlings go through similar drastic changes in form. Think, for example, of the caterpillar and butterfly, or the tadpole and adult frog.

    Scientists have studied the life history of animals, part of a field called development, for many decades. Other scientists have studied how life arose and evolved on Earth. But for the first ...

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  1. An Astronomy First: Telescopes Double-Team Hawaiian Night Sky

    Text based on a NASA Press Release

    Proving that two telescopes are better than one, NASA astronomers have gathered the first starlight obtained by linking two Hawaiian 10-meter telescopes.

    This successful test at the W.M. Keck Observatory on Mauna Kea makes the linked telescopes, which together are called the Keck Interferometer, the world’s most powerful optical telescope system. The project will eventually search for planets around nearby stars and help NASA design future space-based missions that can search for habitable, Earthlike planets.

    “Successfully combining the light from the two largest telescopes on Earth is a fabulous technical advancement for ...

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  1. Through Thick or Thin: Exploring Europa's Outer Layer of Ice

    When NASA’s Galileo spacecraft sent back images and data of the Jovian moon Europa, scientists began thinking seriously that life just might exist on this enigmatic, frozen world.

    Europa appears to have all the conditions necessary for the emergence of life: liquid water, organic chemicals, and energy. A layer of ice covers Europa, but there is strong evidence – the most convincing comes from Galileo’s magnetometer – that a salty ocean may lie underneath. Organic chemicals are prevalent throughout the universe and could have been deposited on Europa by comets and meteors. Tidal forces exerted by Jupiter could provide ...

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  1. Looking for Signs of Life in Acid-Washed Rocks

    Extraordinary clues to the history of biological evolution on Earth often come from something as mundane as rocks. To better understand the close connection between life and geology—and how one affects the other—new laboratory methods are being developed to tease out the information that ancient rocks contain.

    Pioneering one such method is Dr. Frances Westall, paleobiologist for the Lunar and Planetary Institute and member of the NASA Astrobiology Institute. She and her colleagues are using acid vapor to isolate the remains of tiny microbial life forms. These fossils, entombed within ancient sedimentary fossil structures known as stromatolites, were ...

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  1. TNA World

    DNA is the building block for life on Earth. But it is a highly complex molecule, and could not have arranged itself spontaneously. What did it develop from? Astrobiologists examine possible ancestors of DNA: nucleic acids called PNA, p-RNA, and TNA.

    We all know that DNA (Figure 1) makes up the building blocks for life on Earth. But DNA – deoxyribonucleic acid – is highly complex. It could not have appeared spontaneously; it must have evolved from a simpler form.

    Scientists have put forth the theory that RNA – ribonucleic acid (Figure 2) – was the predecessor to DNA ...

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  1. Ganymede's Liquid Past

    Based on a NASA Ames Research Center press release

    Long swaths of bright, flat terrain on the surface of Jupiter’s icy moon Ganymede may testify that water or slush emerged there about a billion years ago, say planetary scientists. NASA scientists have combined stereo images from NASA’s Galileo and Voyager missions to examine these provocative features on the moon.

    This bright terrain, long since frozen over, lies uniformly in troughs about one kilometer (a little over a half mile) lower than Ganymede’s older, darker, cratered terrain.

    Ganymede is the largest moon in the solar system and larger than the ...

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