[NASA is certainly on a roll. After their blockbuster announcement of possible ancient life on Mars on August 7, what could they possibly say this week to keep up the momentum? How about the existence of water on Jupiter's mysterious moon Europa, already considered by some space scientists as the best place (apart from Earth) to find life in our solar system? The following text is edited from a NASA press release dated August 13, 1996, plus additional remarks from NASA chief administrator Daniel Goldin.]
Tantalizing new images of Jupiter's moon Europa from NASA's Galileo spacecraft indicate that "warm ice" or even liquid water may have existed, and perhaps still exists today beneath Europa's cracked icy crust.
The Europa results are among several new Galileo findings released [August 13] in a news briefing at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA.
Galileo scientists are poring over images that show places on Europa resembling ice floes in Earth's polar regions, along with suggestions of geyser-like eruptions and details of long dark bands centered with white stripes that stretch like interstate highways across Europa's face.
"This moon is a marvelous place," said Dr. Ronald Greeley, a Galileo imaging team scientist and a geologist at Arizona State University, Tempe, AZ. "We're seeing evidence of a lot of geological activity on Europa."
"In some areas, the ice is broken up into large pieces that have shifted away from one another, but obviously fit together like a jigsaw puzzle," said Greeley. "This shows the ice crust has been or still is lubricated from below by warm ice or maybe even liquid water."
The results bring scientists a step closer to determining whether Europa has environmental "niches" warm enough and wet enough to meet the requirements to host life, Greeley said.
Europa is about the size of Earth's Moon and is covered largely with smooth white and brownish-tinted ice, instead of large craters like so many other bodies in the Solar System. Scientists believe its cracked cue-ball appearance is due to stressing caused by the contorting tidal effects of Jupiter's strong gravity. They speculate that the warmth generated by tidal heating may have been sufficient to soften or even liquefy some portion of Europa's icy covering.
Europa has long been considered by scientists and celebrated in science fiction as one of the handful of places in the Solar System (along with Mars and Saturn's moon Titan) that could possess an environment where primitive forms of life could possibly exist.
"A major goal of Galileo's studies of Europa is to search for signs of current or past activity to help answer the question: Is there a liquid zone on Europa?" said Greeley. "We are interested in identifying the time and places on Europa where liquid water might exist. We want to go back to some of these areas that suggest soft ice or liquid water under the ice and test some of the questions we're asking now."
The current images, taken from a distance of about 95,700 miles (155,000 kilometers), show features about one mile across (1.6 kilometer per pixel resolution). Moon flybys later in the mission will bring the Galileo spacecraft to within 370 miles (600 kilometers) of Europa's surface. During those flybys, the best resolution from the camera will average about 72 to 98 feet (22 to 30 meters- per-pixel) and as fine as 36 feet (11 meters) per pixel, so that objects the size of buildings on Earth could be discerned, Greeley said.
Galileo's close flybys of Europa will occur Dec. 19, 1996, Feb. 20, 1997 and Nov. 6, 1997. Additional non-flyby observations will be made during this September and November, and in April, June and September of 1997.
NASA chief administrator Daniel Goldin issued a separate press release on August 13 regarding the new Europa data. It read, in part:
"These fantastic new images of an icy moon of Jupiter are reminiscent of the ice-covered Arctic Ocean on our planet. The lack of craters, the cracks and signs of movement, all indicate that this might be young ice on a dynamic surface. It raises the possibility of a liquid ocean on Europa, the only other place in our solar system where we suspect such an ocean might exist.
"These pictures do not prove the existence of liquid water on Europa, and the higher-resolution pictures yet to come may not prove it. A few days ago, I greeted the possibility of ancient microbial life on Mars with skeptical optimism, and invited further scientific examination and debate. I greet the new pictures of Europa in the same light.
"The potential for liquid water on Europa is an intriguing possibility, and another step in our quest to explore the solar system, the stars, and the answer to the great mystery of whether life exists anywhere else in the cosmos.
"We won't wait for all the answers. We'll release the data as soon as it's available, and share the excitement of discovery not only with scientists, but with the American public."
[ISCNI*Flash applauds Goldin's stated philosophy of openness and hopes this will extend to the new photos soon to be taken (in late 1997) of the Cydonia region of Mars.]
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