Searching for Life While Tending the Home Fires
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September 26, 1997
"We are now reaping the harvest from those missions we developed over the last 10 to 12 years," Dr. Wes Huntress, NASA associate administrator for space science, said Thursday at the Defense and Space Programs and Conference of the American Institute of Aeronautics and Astronautics held here September 23-25.
"Beginning in the 21st century, the first fruits of this new generation of smaller, more frequent missions will yield a tremendous increase in the discovery rate and the excitement rate."
Huntress cited this summer's highly successful Mars Pathfinder mission as an example. Pathfinder and its Sojourner rover have returned thousands of images from the surface of Mars, and volumes of data about soil and rock composition.
"We couldn't have done it a few years ago" with technologies then available, he said. Advances in micromachines and intelligent systems will make possible more detailed exploration of the planets and will enhance the search for life.
In addition to Mars - where Pathfinder found new evidence of running water - Huntress said NASA wants to go back to Europa, one of the four largest moons of Jupiter. The Galileo spacecraft orbiting Jupiter flew past Europa this year and returned data indicating that the Jovian moon has an ocean beneath a crust of ice. The image at right shows the limb of Europa. Europa's apparent smooth shape is from constant resurfacing of the ice covering the planet.
The search for life will be conducted from home, too. Huntress described
how a proposed Space Interferometry
Mission, in Earth orbit, could be assembled with several medium-size
telescopes spanning 100 meters (330 feet) to provide unprecedented resolution
in searching for planets around nearby stars. The Space Interferometer,
will be a large, deployable satellite using several telescopes to achieve
the same resolution (though not the same brightness)
as a single larger telescope. An artist's conception is shown above. (The search for planets and life is part of NASA's Origins Program.)
By around 2020, SIM could produce a "family portrait" of planets orbiting stars up to 30 light years away. Spectroscopy will show whether the atmospheres have water, oxygen, and carbon dioxide - signs that life might be present.
Huntress also suggested that an image of a distant planet with atmosphere and clouds "will change human beings as profoundly" as did the first Apollo images of the Earth in space in the 1960s. How the Earth in space is affected by the Sun was discussed by Dr. George Withbroe, director of solar physics at NASA headquarters.
Withbroe said the study of solar activities has applications beyond scientific curiosity: it affects how we live on Earth. The Department of Defense, he said, estimates that unpredictable variations in solar activities cost it about $500 million a year in damage to satellites, electrical systems on Earth, and other problems. In April, the civilian Tempo 2 communications satellite lost 10 percent of its electrical capability to damage caused by a coronal mass ejection from the Sun. (The April CME, at left, was imaged by the LASCO instrument on board the Solar and Heliospheric Observatory.)
The Sun is now pulling out of its period of minimum activity and building towards a sunspot maximum that will occur around 1999-2001.
Increased activity will affect how the ionosphere transmits radio waves which can alter timing signals from navigational satellites on which ships, airliners, and other vehicles increasingly rely for precision guidance.
The effects of solar activity on climate also are unknown, Withbroe added. (Today, Science magazine carries results of a study indicating that the Sun is warming slightly, which could affect global warming calculations.)
The Space Sciences Laboratory at NASA's Marshall Space Flight Center
is involved in several aspects of the quest to understand
the behavior of the Sun. Studies range from observations of the
Sun itself and studies of how flares and sunspots behave, to detailed studies
of how the Earth's magnetic field and outer atmosphere react to those activities.
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