This image of Vesta released by NASA was captured by the Dawn spacecraft on July 9, 2011, and was taken from a distance of about 62,000 miles (100,000 kilometers) away from the protoplanet. Each pixel in the image corresponds to roughly 5.8 miles. NASA/AP
This undated image taken by the Dawn spacecraft and provided by NASA on Dec. 27, 2011, shows a close-up view of a huge crater in the southern hemisphere of the Vesta asteroid. A recent analysis of images taken by Dawn reveals there are two overlapping craters in Vesta's south pole created by separate impact events. NASA/AP
This set of color images of asteroid 243 Ida was taken by the imaging system on the Galileo spacecraft as it approached and raced past the asteroid on August 28, 1993. These images were taken through the 4100-angstrom (violet), 7560-angstrom (infrared) and 9680- angstrom (infrared) filters and have been processed to show Ida in exaggerated color to bring out subtle color contrasts caused by small variations in composition and surface microtexture of the asteroid's soil. NASA
This artist's concept depicts a distant hypothetical solar system, similar to the one recently discovered with the Spitzer Space Telescope. In this artist's rendering, a narrow asteroid belt filled with rocks and dusty debris, orbits a star similar to our own Sun when it was approximately 30 million years old (about the time Earth formed). NASA/JPL-Caltech/T. Pyle (SSC)
The impact of an asteroid or comet several hundred million years ago left scars in the landscape that are still visible in this spaceborne radar image of an area in the Sahara Desert of northern Chad. The concentric ring structure is the Aorounga impact crater, with a diameter of about 10.5 miles. The original crater was buried by sediments, which were then partially eroded to reveal the current ring-like appearance. NASA/JPL-Caltech
These views of the asteroid Eros were generated by data from the laser rangefinder. This false color image shows the 'gravity slope' at various regions on the object. The gravity slope is the angle between the local gravitation field (computed assuming a constant density for the asteroid) and the normal to the surface. Blue is low slope, red is high slope. NASA/Goddard Space Flight Center Scientific Visualization Studio
This painting shows an asteroid mining mission to an Earth-approaching asteroid. Asteroids contain many of the major elements which provide the basis for industry and life on Earth. A NASA-sponsored study on space manufacturing held at Ames Research Center (ARC) in the summer of 1977 provided much of the technical basis for the painting. Denise Watt/NASA
This artist's animation illustrates a massive asteroid belt in orbit around a star the same age and size as our Sun. Evidence for this possible belt was discovered by NASA's Spitzer Space Telescope when it spotted warm dust around the star, presumably from asteroids smashing together. NASA/JPL-Caltech
This is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from the NASA's Galileo spacecraft -- the first conclusive evidence that natural satellites of asteroids exist. Ida, the large object, is about 35 miles long. Ida's natural satellite is the small object to the right. NASA/JPL-Caltech
While analyzing NASA Hubble Space Telescope images of the Sagittarius dwarf irregular galaxy (SagDIG), an international team of astronomers led by Simone Marchi, Yazan Momany, and Luigi Bedin were surprised to see the trail of a faint asteroid that had drifted across the field of view during the exposures. The trail is seen as a series of 13 reddish arcs on the right in this August 2003 Advanced Camera for Surveys image. NASA, ESA, and Y. Momany (University of Padua)
Pioneer 10 crosses the asteriod belt in this artist's concept. If spacecraft are to visit the outer Solar System, they must cross the asteroid belt between Mars and Jupiter. The Pioneer mission was faced with the question of just how dangerous this asteroid belt would be to a spacecraft passing through it. Rick Guidice/NASA
An artist's rendering of the the Near Earth Asteroid Rendezvous (NEAR) spacecraft's rendezvous with the asteroid Eros is seen here. Upon arrival, the spacecraft would orbit the mountain-sized body for nearly 13 months, sending back the first comprehensive dataset about an asteroid. This image produced for NASA by Pat Rawlings. Technical concepts for NASA's Exploration Office, Johnson Space Center (JSC). 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.