Scientists look at how nitrous oxide could have played a role in keeping early Earth ice-free.
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 ...July 13, 2001 • Posted by: Shige Abe • Report issue
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 ...July 09, 2001 • Posted by: Shige Abe • Report issue
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 ...July 06, 2001 • Posted by: Shige Abe • Report issue
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 ...June 22, 2001 • Posted by: Shige Abe • Report issue
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 ...June 18, 2001 • Posted by: Shige Abe • Report issue
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 ...June 15, 2001 • Posted by: Shige Abe • Report issue
Based on a Washington University in St. Louis press release
Massive erosion shaped the surface of Mars, according to planetary scientists at Washington University in St. Louis. While hunting for safe but geologically-rich landing sites for NASA’s 2003 Mars Exploration Rover (MER) missions, researchers have combed images of the sandy plains in a region of Mars called Arabia Terra.
Brian M. Hynek, doctoral candidate in Earth and Planetary Sciences, and Roger J. Phillips, Ph.D., professor of earth and planetary sciences and director of Washington University’s McDonnell Center for the Space Sciences, suggest that early in Mars’ history, western ...June 13, 2001 • Posted by: Shige Abe • Report issue
Based on a NASA press release
The first continuous global observations of the biological engine that drives life on Earth – the countless forms of plants that cover the land and oceans – were published in the March 30 issue of the journal Science.
This study is based on the first three years of daily observations of ocean algae and land plants from the Sea-viewing Wide Field-of-View Sensor, or SeaWiFS, mission, creating the most comprehensive global biological record ever assembled. Scientists will use the new record of the Earth’s surface to study the fate of carbon in the atmosphere, the ...June 06, 2001 • Posted by: Shige Abe • Report issue
Adapted from a European Space Agency press release
Astronomers have known for decades that there is a lot of water in space. Hydrogen is the most common element in the Universe, and oxygen is made in stars and dispersed by events such as supernova explosions. The two elements mix in star-forming clouds and form large amounts of water (H2O). But because astronomers couldnâ€™t measure gaseous water in cold clouds in space, they couldnâ€™t be sure of the exact amount of water in those regions.
“Weâ€™ve known for a long time that there is a lot of water ...June 04, 2001 • Posted by: Shige Abe • Report issue
Based on a Penn State University press release
Glacial deposits that formed on tropical land areas during snowball Earth episodes around 600 million years ago, lead to questions about how the glaciers that left the deposits were created. Now, Penn State geoscientists believe that these glaciers could only have formed after the Earth’s oceans were entirely covered by thick sea ice.
“There is strong geologic evidence of tropical glaciation at sea level during those times,” Dr. David Pollard, research associate, Penn State College of Earth and Mineral Sciences’ Environmental Institute, told attendees at the spring meeting of the American ...June 01, 2001 • Posted by: Shige Abe • Report issue
Initially, the surface of our planet was a fiery, molten stew. These early hellish conditions inspired scientists to call the time period from 4.5 to 3.8 billion years ago the “Hadean” era.
But the Earth was not molten all throughout the Hadean. Within a few million years, the crust cooled and water vapor rained down to form the oceans, although the inside of the planet still remained very hot. It is thought that life soon after may have made its first appearance on Earth, either in the newly formed oceans, or in clay or rocks within the Earth’s ...May 30, 2001 • Posted by: Shige Abe • Report issue
Based on an article by Science@NASA
Last year comet C/1999 S4 (better known as “Comet LINEAR”) surprised astronomers by breaking apart as it passed near the Sun. Now the long-dead comet has surprised them again: New research shows Comet LINEAR was likely made up of water with the same isotopic composition as water found here on Earth. The finding supports a controversial idea that cometary impacts billions of years ago could have provided most of the water in Earth’s oceans.
“The idea that comets seeded life on Earth with water and essential molecular building blocks is hotly ...May 25, 2001 • Posted by: Shige Abe • Report issue
Adapted from a University of Florida press release
A team of University of Florida scientists has genetically modified a tiny plant to send reports back from Mars in a most unworldly way: by emitting an eerie, fluorescent glow.
The scientists have proposed an experiment that would send 10 varieties of the plant to the Red Planet as a Mars “Scout” mission. Scout missions are focused high-priority science experiments that can be achieved for less than $300 million apiece.
The plant experiment, which is funded by NASA’s Human Exploration and Development in Space program, may be a first step toward ...May 23, 2001 • Posted by: Shige Abe • Report issue
Adapted from a University of Washington press release
A mass extinction about 200 million years ago, which destroyed at least half of the species on Earth, happened very quickly and is demonstrated in the fossil record by the collapse of one-celled organisms called protists, according to new research led by a University of Washington paleontologist.
“Something suddenly killed off more than 50 percent of all species on Earth, and that led to the age of dinosaurs,” said Peter Ward, a UW Earth and space sciences professor.
Evidence indicates the massive die-off was linked with an abrupt drop in productivity ...May 21, 2001 • Posted by: Shige Abe • Report issue
Our Milky Way Galaxy is unusual in that it is one of the most massive galaxies in the nearby universe. Our Solar System also seems to have qualities that make it rather unique. According to Guillermo Gonzalez, Assistant Professor of Astronomy at the University of Washington, these qualities make the Sun one of the few stars in the Galaxy capable of supporting complex life.
For one thing, the Sun is composed of the right amount of “metals.” (Astronomers refer to all elements heavier than hydrogen and helium as “metals.”) Moreover, the Sun’s circular orbit about the galactic center ...May 18, 2001 • Posted by: Shige Abe • Report issue
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