[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Marshall Scientist To Participate In Astrobiology Institute


       Marshall scientist to participate in Astrobiology Institute
       A Marshall Space Flight Center news release
       March 23, 1998

       What started as a hobby for a scientist here has become a new
       line of scientific investigation in the newly formed NASA
       Astrobiology Institute.

       Richard Hoover, a solar physicist at Marshall Space Flight
       Center, is co-investigator on two astrobiology proposals
       which NASA has selected for funding.

       Dr. David McKay of Johnson Space Center is principal
       investigator on a proposal to look for biomarkers in
       astromaterials: signs of life in soil, rocks, and other
       materials from outside the Earth.

       Dr. Kenneth Nealson of the Jet Propulsion Laboratory in
       Pasadena, Calif. is principal investigator on a proposal on a
       study of the co-evolution of planets and biospheres.

       Hoover will be a co-investigator on both proposals.

       "This is really exciting," said Hoover, whose primary work at
       Marshall has been developing advanced telescopes to study the
       sun. "We are going to look at life on Earth in the most
       extreme environments - hot volcanic vents, deep ocean ice,
       and even ancient rocks - and help sharpen our senses when we
       look for signs of life on Mars, Europa, and other
       astromaterials."

       For Hoover, this journey started years ago when he became
       fascinated by diatoms (below), the "living jewels of the
       sea." It became a hobby, then a passion, which has earned him
       international recognition. Most recently, he has applied
       knowledge gained in this area to the search for preserved
       microbes in Antarctic ice cores as a model of
       extraterrestrial life.

       While Mars has long been thought of as the best chance for
       life elsewhere in our solar system, recent evidence of liquid
       water in Europa, one of Jupiter's moons, raises the
       possibility of life there. In turn, the discoveries over the
       past few decades of life in hot springs, deep ocean vents,
       and even Antarctic ice broaden the range of conditions where
       at least basic lifeforms may set up housekeeping.

       In the first investigation, Hoover will work with David McKay
       who startled the scientific community in 1996 with claims
       that he had found evidence of microbial fossils in a rock
       believed to have fallen to Earth from Mars. While the
       evidence within the Allan Hills meteorite, ALH84001,
       continues to be debated, pictures and data from the Mars
       Pathfinder and Mars Global Surveyor missions have added
       evidence that Mars once had flowing water.

       "The primary research that we'll be doing is looking
       microfossils in ancient rocks," Hoover said. He anticipates
       analyzing phosphorites from Mongolia, oil shale from Siberia,
       and other formations dating back about 3.8 billion years. The
       search for fossils of bacteria and archaea will be of prime
       importance.

       Life is divided into three principal domains, eukaryotes
       (large cells, such as plants and animals), bacteria, and
       archaea. Archaea, only discovered in 1977, normally thrive in
       extreme conditions like the hot springs of Yellowstone
       National Park, thermal vents deep underwater in the
       mid-Atlantic ridge, highly acid and alkaline baths, and deep
       rocks. These are not normal conditions now, but were more
       than 3 billion years ago.

       "It's now looking like the archaea are among the most ancient
       forms of life on Earth," Hoover said. And the implication is
       that if life could originate and then thrive under such
       conditions here, then it could do the same on Mars and Europa
       - perhaps even volcanic Io - where conditions are considered
       inhospitable.

       Under the biosphere evolution study with Nealson at JPL,
       Hoover will develop methods to fix, prepare, and view samples
       so that unambiguous indications of life - or non-life - can
       be obtained. He will use advanced tools such as the Scanning
       Electron Microscope (ESEM) and atomic-force microscope that
       NASA/Marshall already has for engineering work.

       "One of the things that's important in preparation techniques
       is making sure that you get no interference from the
       substrate in the X-ray spectral analysis," Hoover said.
       NASA/Marshall's ESEM is especially good at analyzing
       biological materials without the need for special coatings.

       The detail revealed by the ESEM offers new challenges.

       "The most critical thing is getting to the ability to
       recognize different types of microorganisms in tools such as
       the ESEM," Hoover said. "It's a very powerful tool, but it
       shows you things that you don't see in optical microscopes or
       conventional electron microscopes." That can mean relearning
       how to recognize creatures that you already know.

       Recognizing and classifying microbes and bacterial fossils in
       this manner will be doubly important in a field that has
       thousands of unnamed microbes. The rule in the international
       microbiology community is that an organism is not named
       unless it is grown in a pure culture and is lodged -
       physically - in a recognized cell bank.

       "In many cases, these bugs can't be grown in pure culture,"
       Hoover said. Asking a bacterium from a deep ocean vent to
       grow in a lab culture is like asking a human to breath a
       vacuum. It takes more than recreating conditions like water
       temperatures above boiling (intense pressure keeps that water
       from boiling). Some creatures only survive with certain
       neighbors, like one bacteria that releases methane and
       another that consumes it.

       Another challenge will be recognizing life when you see it.
       Hoover said he was recently stumped by a microsphere with a
       lot of iron. He was told by a colleague that it was indeed a
       bacterium that consumes iron sulfate - FeSO3 - to get oxygen.

       "That tells me that we have to learn the kinds of things that
       go on inside an electron microscope, and in other tools, with
       respect to microbiology," Hoover said, "because these are the
       kinds of tools we'll take to Mars and Europa when we look for
       life."

       "It's extremely important that we continue to learn and to
       develop an enhanced knowledge of microfossils, and of
       bacteria, eukaryotes, and archaea."
Follow-Ups: