NASA: Phoenix Mars Lander is now silent
WASHINGTON, Dec. 2 (UPI) -- The U.S. space agency says it has, most likely -- after a month of fruitless attempts -- reached the end of communications with its Phoenix Mars Lander.
The National Aeronautics and Space Administration said it has ceased its daily attempts to communicate with the spacecraft and has stopped using its Mars orbiters to hail the lander and listen for its signals.
"The final communication from Phoenix remains a brief signal received via NASA's Mars Odyssey orbiter on Nov. 2," the space agency said. The Phoenix lander operated for two months longer than expected after achieving its science goals during its original three-month mission. It landed on a Martian arctic plain on May 25.
The last attempt to listen for a signal occurred at 3:49 p.m. Saturday, on the 182nd Martian day since Phoenix landed on Mars.
Heart's helical band motion studied
PASADENA, Calif., Dec. 2 (UPI) -- U.S. scientists say they've created, for the first time, images of the heart's muscular layer and the link between it and the way the heart contracts.
California Institute of Technology researchers say their findings could help create a road map for future cardiac surgical techniques.
The researchers showed the muscular band that wraps around the inner chambers of the heart in a helix is actually a sort of "twisting highway" along which each contraction of the heart travels.
"The heart twists to push blood out the same way you twist a wet towel to wring water out of it," said Professor Morteza Gharib, who led the study.
Using a new imaging technique pioneered by Han Wen and colleagues at the National Institutes of Health, Gharib and Abbas Nasiraei Moghaddam created some of the first dynamic images of normal myocardium -- the middle muscular layer of the heart wall -- in action at the tissue level.
"We tagged and traced small tissue elements in the heart, and looked at them in space, so we could see how they moved when the heart contracts," Gharib said. "In this way, we were able to see where the maximum physical contraction occurs in the heart and when, and to show that it follows this intriguing helical loop."
The research appeared in the December issue of Heart and Circulatory Physiology.
Endeavour to return to Florida
EDWARDS AIR FORCE BASE, Calif., Dec. 2 (UPI) -- The U.S. space agency says space shuttle Endeavour is being readied to make its cross-country trip back to the Kennedy Space Center in Florida.
The National Aeronautics and Space Administration said Endeavour ended its latest mission to the International Space Station with a landing Sunday at Edwards Air Force Base in California. The spacecraft is now being mounted atop a modified Boeing 747 shuttle carrier aircraft and is expected to begin its journey to Florida as early as next Sunday.
"The exact date and time of departure have yet to be determined because of changing weather conditions and the fluid nature of preparing Endeavour for this ferry flight," NASA said in a statement.
During the shuttle's 16-day journey of more than 6.6 million miles to the ISS, the STS-126 crew conducted important repair work and prepared the space station to house six crew members on long-duration missions, NASA said.
Rapid, unexpected climate changes posited
BINGHAMTON, N.Y., Dec. 2 (UPI) -- A U.S. geologist is warning the Earth might soon undergo rapid and unpredictable climate changes that could negatively affect many species.
Binghamton University Professor Tim Lowenstein's concerns are rooted in his and Professor Robert Demicco's discovery of nahcolite -- a rare carbonate mineral that formed during the Eocene Epoch, the warmest period on Earth during the last 65 million years.
Lowenstein and Demicco said nahcolite suggests Eocene warming was concurrent with atmospheric carbon dioxide levels of at least 1,125 parts per million, which is 3 times current CO2 levels, but not much higher than what's expected on Earth in about 100 years.
"Right now, we're on a predictable pace," said Lowenstein. "But there will likely be tipping points -- unexpected events that could really change things -- so all of a sudden we may get changes in ocean circulation that we never would have predicted, or the tundra may melt.
"Some unexpected event is going to occur that's going to be more dramatic than the progressive changes that occurred over the last 100 years."
If we keep doing what we're doing now, we will be up to the CO2 levels of the Eocene within another 100 or 200 years," he said, adding that "hothouse" world of 50 million years ago should serve as a reminder of what global changes are possible.