Shuttle Endeavour and Astronauts

Former astronaut Charles Bolden picked to lead NASA

Nineteen years after helping launch the Hubble Space Telescope, Charles F. Bolden Jr., a former combat pilot, Marine Corps major general and veteran space shuttle commander, has been selected by the Obama administration to serve as the space agency's next administrator. Lori Garver, a former NASA associate administrator for policy and plans and a space policy advisor to the Obama campaign, will serve as Bolden's deputy.

These talented individuals will help put NASA on course to boldly push the boundaries of science, aeronautics and exploration in the 21st century and ensure the long-term vibrancy of America's space program," Obama said in a statement Saturday.

Astronauts test re-entry systems for Friday landing

The Atlantis astronauts tested the shuttle's re-entry systems early Thursday and began packing for landing Friday, weather permitting, to close out a successful mission to overhaul the Hubble Space Telescope. The flight plan calls for a de-orbit rocket firing at 8:49:16 a.m. Friday, setting up a landing on runway 15 at the Kennedy Space Center at 10:00:31 a.m. A second landing opportunity is available one orbit later, at 11:39:18 a.m.

With no major technical problems in orbit, the only question mark is the weather, with forecasters predicting a broken cloud deck at 4,000 feet, crosswinds above 15 knots and a chance of thundershowers within 30 nautical miles of the runway, all violations of NASA's landing weather flight rules.

High winds and torrential rains rumbled through the area overnight as severe thunderstorms lashed Florida's Space Coast. There is a 50 percent chance of heavy rain, high winds and thundershowers all day Thursday and more of the same expected overnight and Friday.

But the astronauts have conserved power and now have saved enough hydrogen and oxygen to power the ship's electricity producing fuel cells through Monday. As a result, NASA is not staffing backup landing sites Friday. If the weather or some other issue blocks the two available landing opportunities, the crew will stay in orbit an extra day and try again Saturday.

Space tours make bones brittle of astronauts

Astronauts who spend long time in space lose bone strength.

Orthopaedic researchers study the hipbone or spine to see effects of long-duration spaceflight.The hip experiences the greatest rate of bone loss in space and a hip fracture requires a major surgery. A person's ability to walk can be lost or in worst case death of the person.

To lessen the effects, space station astronauts must exercise at least two hours every day and undergo weeks of rehabilitation after their return to Earth.