This is an artist's concept depicting a possible scene when the first human travelers might walk on the surface of Mars. The artwork was part of a NASA new initiatives study which surveyed possible future manned planetary expeditionary activity. NASA
Backdropped by the blackness of space and Earth's horizon, the International Space Station moves away from Space Shuttle Discovery in 2006. Earlier the STS-116 and Expedition 14 crews concluded eight days of cooperative work onboard the shuttle and station. This image was recorded with a 35mm film-equipped camera. NASA
This infrared image taken by NASA's Wide-field Infrared Survey Explorer, or WISE, shows a star-forming cloud teeming with gas, dust and massive newborn stars. WISE, which is surveying the whole sky in infrared light, is particularly sensitive to the warm dust that permeates star-forming clouds like this one. In this way, WISE complements visible-light observations. NASA/JPL-Caltech/UCLA
Leaving the clouds behind, the Delta II rocket carrying the robotic Dawn spacecraft arcs through the blue sky over the Atlantic Ocean in 2007. Dawn was the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. NASA/George Shelton
A test subject wears a pressurized 'space' suit for the Reduced Gravity Walking Simulator located at the Lunar Landing Facility in 1965. The purpose of this simulator was to study the subject while walking, jumping or running. Researchers conducted studies of various factors such as fatigue limit, energy expenditure, and speed of locomotion. NASA Langley Research Center
Reflecting on his experience as he emerged from the craft into the daylight on the Expedition 24 mission's second spacewalk on Aug. 11, astronaut Doug Wheelock said "the colors of the Earth just explode at you as you exit toward the planet. Notice what looks like scorch marks on the hatch thermal cover, the effect of vacuum and atomic oxygen on the threads and thread sealant used on the thermal cover. The 'smell' of space follows suit, I’ve heard it described like burnt cake or cookies, or like the smell of an extinguished match." NASA
Space Shuttle Discovery sits on Launch Pad 39B after its approximately 5-hour rollout from the Vehicle Assembly Building. At center left can be seen the White Room, the environmentally controlled chamber that provides entry into the orbiter for the astronaut crews. The chamber is at the end of the Orbiter Access Arm, which has not been extended yet. At the bottom of Discovery's left wing is the tail service mast, one of two belonging to the Mobile Launcher Platform on which the Shuttle rests. NASA Kennedy Space Center
This is a wide angle view of the martian north polar cap as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera in early northern summer. The picture was acquired on March 13, 1999, near the start of the Mapping Phase of the MGS mission. NASA/JPL/MSSS
A large, bright and complex convective storm that appeared in Saturn's southern hemisphere in mid-September 2004 was the key in solving a long-standing mystery about the ringed planet. Saturn's atmosphere and its rings are shown here in a false color composite made from Cassini images taken in near infrared light through filters that sense different amounts of methane gas. NASA
A NASA DC-9 reduced-gravity aircraft is featured in this image during a parabolic flight photographed from a T-38 aircraft. The aircraft, based at Ellington Field near Johnson Space Center, flies a series of parabola patterns over the Gulf of Mexico to afford opportunities for astronauts and investigators to experience brief periods of weightlessness. NASA
While officials agree that conditions are much improved in Sierra Leone, Liberia, and Guinea, it's unclear if this Ebola outbreak could have been responded to quicker, with less cost and suffering.
ByKrista Larson and Maria Cheng, Associated Press
A top U.N. official in the fight against Ebola greeted just three patients at one treatment center he visited this week in Sierra Leone. Families in Liberia are no longer required to cremate the remains of loved ones to halt the spread of the virulent disease.