|
|
|
|
|
Best bet for locating Mars life ARIZONA STATE UNIVERSITY NEWS RELEASE Posted: February 20, 2007 SAN FRANCISCO, Calif. -- Hunting for traces of life on Mars calls for two radically different strategies, says Arizona State University professor Jack Farmer. Of the two, he says, with today's exploration technology we can most easily look for evidence for past life, preserved as fossil "biosignatures" in old rocks. Farmer is a professor of geological sciences in ASU's School of Earth and Space Exploration, where he heads the astrobiology program. He is reported on his work at the annual meeting of the American Association for the Advancement of Science in San Francisco. "Searching for extraterrestrial life must follow two alternative pathways, each requiring a different approach and tools," Farmer says. "If we're looking for living organisms, we are doing exobiology. But if we are seeking traces ‹ biosignatures ‹ of ancient life, it's better to call it exopaleontology." Unfortunately, he notes, "for the next 10 or 15 years, technology limitations will force us down the exopaleontology path." The core issue is accessibility. "To find living organisms on Mars," says Farmer, "you need to find liquid water. Because liquid water is unstable on the Martian surface today, that means going deep into the subsurface." Water saturates the ground in high latitudes north and south, and around both poles, only a few inches below the surface, Farmer explains. But this water remains frozen year round. "Environments with liquid water will likely lie far deeper, perhaps miles below the surface." Organisms have been found living in fractured rock, thousands of feet underground on Earth, Farmer notes. "But with current robotic technology, we simply can't drill that deep on Mars." Terrestrial deep drilling requires complex, heavy equipment, plus constant supervision and troubleshooting by human crews. Says Farmer, "We'll be lucky if, in the next decade or so, robotic drilling on Mars reaches a depth of a couple yards." So where does that leave us in the search for life on Mars? Farmer says our best choice is to pursue the exopaleontology path. "Finding the signatures of an ancient Martian biosphere means exploring old rocks that might preserve traces of life for millions or billions of years," Farmer notes. Among the best places to look on Mars, he says, are deposits left by springs and former lakes in the heavily cratered highlands. "The rocks there date from a period in Martian history when liquid water was common at the surface." In fact, says Farmer, conditions on Mars then were likely similar to those on the early Earth at the time when life began. "Besides water, life also requires energy sources and organic chemical building blocks," Farmer explains. "The Mars Exploration Rover Opportunity found ample evidence for water in ancient rocks at Meridiani Planum, but the rovers' instruments can't detect organic materials." However, NASA's next rover, the Mars Science Laboratory, will carry instruments to analyze traces of organic substances. It is due for launch in 2009. Recognizing a Martian fossil may be difficult. "We're not talking about stumbling over dinosaur bones," Farmer says. Instead, the discovery may involve finding biologically formed structures in old sedimentary deposits, perhaps like stromatolites found here on Earth. Stromatolites are distinctive structures that form in shallow oceans, lakes, or streams where microbial colonies trap sediments to form thin repeating layers. Stromatolites also contain microscopic cellular remains and chemical traces left by the microbes that formed them. Taken together, such structures comprise the primary record of life in ancient rocks on Earth. For hunting Martian fossils, says Farmer, we will need robotic microscopic imagers capable of viewing rocks in many wavelengths as well as seeing details as small as a hundredth of a millimeter across. Also needed are organic chemistry laboratories to analyze promising rocks. "That will help us avoid mistaking non-biological features for biological ones," he says. Farmer's fieldwork has taken him to extreme microbial habitats in Iceland, New Zealand, Yellowstone National Park, and Mono Lake, Calif. He has sought to understand how modern microbial communities become preserved as fossils. Their environments, he notes, span physical and chemical conditions believed to be representative of early Mars. "Studying how microbes become fossils is a key step in developing an effective strategy for exopaleontology," Farmer says. "It will help us find the best places to explore on Mars and how to look." |
|
|
|
 |
||||||||||||||||||||
After a six-hour trip along the three-and-a-half-mile crawlerway from the Vehicle Assembly Building, space shuttle Atlantis arrives at launch pad 39A for the STS-117 mission.
Space shuttle Atlantis emerges from its processing hangar at dawn February 7 for the short trip to the Vehicle Assembly Building at Kennedy Space Center's Complex 39.
Shuttle Columbia carried the first United States Microgravity Laboratory during its summer 1992 flight to orbit. The Spacelab science expedition was the longest shuttle mission to date, thanks to the new Extended Duration Orbiter equipment flown for the first time. The crew of STS-50 narrate the highlights in this post-flight film.
The documentary "Research Project: X-15" looks at the rocketplane program that flew to the edge of space in the effort to learn about the human ability to fly at great speeds and aircraft design to sustain such flights.
On the 40th anniversary of the Apollo 1 fire that took the lives of astronauts Gus Grissom, Ed White and Roger Chaffee, a remembrance service was held January 27 at the Kennedy Space Center's memorial Space Mirror.
This documentary takes a look at the technical aspects of Project Mercury, including development of the capsule and the pioneering first manned flights of America's space program.
The voyage of Apollo 15 took man to the Hadley Rille area of the moon. Astronauts Dave Scott and Jim Irwin explored the region using a lunar rover, while Al Worden remained in orbit conducting observations. "Apollo 15: In the Mountains of the Moon" is a NASA film looking back at the 1971 flight.
Skylab, America's first space station, began with crippling problems created by an incident during its May 1973 launch. High temperatures and low power conditions aboard the orbital workshop forced engineers to devise corrective measures quickly. Astronauts Pete Conrad, Paul Weitz and Joe Kerwin flew to the station and implemented the repairs, rescuing the spacecraft's mission. This film tells the story of Skylab's first 40 days in space.
NASA's New Horizons space probe will fly past Jupiter in late February, using the giant planet's gravity as a sling-shot to bend the craft's trajectory and accelerate toward Pluto and the Kuiper Belt. Mission officials describe the science to be collected during the Jupiter encounter during this briefing.