科技英语新闻:NASA spacecraft data suggest Mars may have flowing saltwater

WASHINGTON, Aug. 4 (Xinhua) -- Observations from NASA's Mars Reconnaissance Orbiter have revealed possible flowing water during the warmest months on Mars, the U.S. National Aeronautics and Space Administration (NASA) announced Thursday.

Dark, finger-like features appear and extend down some Martian slopes during late spring through summer, fade in winter, and return during the next spring. Repeated observations have tracked the seasonal changes in these recurring features on several steep slopes in the middle latitudes of Mars' southern hemisphere.

"The best explanation for these observations so far is the flow of briny water," said Alfred McEwen of the University of Arizona, Tucson.

McEwen is the principal investigator for the orbiter's High Resolution Imaging Science Experiment and lead author of a report about the recurring flows to be published in Friday's edition of the journal Science.

Seven such sites on the planet have been confirmed, with 20 more possible, McEwen said.

"What makes these new observations so interesting is they occur at much lower latitudes where temperatures are much warmer and where it's actually possible for liquid water to exist," said Arizona State University geophysicist Phil Christensen, one of the scientists who studied the images beamed back from the orbiter.

The study does not prove water exists, but identifies it as the best explanation. It's worthwhile to think about alternative reasons for these observations, but none seems to fit as well as briny water, McEwen said.

"I think it's going to be laboratory experiments on Earth that give us the best confirmation or refutation," he said.