Dawn Launch Date Pushed to September

NASA's Dawn Spacecraft, a mission to go to the asteroid belt to study its two largest objects, Ceres and Vesta, was scheduled to launch no later than the 15th . Today NASA Officials have decided to postpone the launch until September.

NASA Officials, Managers, and its Head Administrator decided that the Dawn launch could possibly interfere or impact the launch preparations for NASA's Phoenix mission that is headed to Mars. The Phoenix Mars Lander will be lifting off in early August.

This September launch date will cause Dawn to miss the latest launch window, July 19. That window allowed Dawn to receive a sling-shot from mars to speed up the mission, but now NASA has decided to use the other launch window to receive a sling-shot from Mars, in September.

Pictured: NASA's Dawn Spacecraft, sent to study asteroid belt. Image Credit: NASA
NASA says that even with Dawn taking-off in September, it will still be able to maintain all of its science missions goals the same way as if it had taken off in July. NASA will discuss the Phoenix Mars Lander and provide more information about the Dawn spacecraft in a press conference tomorrow (July 8) 11:30 AM Eastern time.

Hubble Photographs Two Asteroids

By: Robert Roy Britt (Space.com)

The Hubble Space Telescope has imaged two of the largest known asteroids, revealing craters and other features that will soon be the targets of close-up observations by NASA's Dawn spacecraft.

Ceres is round , like a planet, and 590 miles (950 kilometers) wide. The rock, about the size of Texas, contains some 30 to 40 percent of all the mass in the asteroid belt between Mars and Jupiter.

Thought to be a planet after its discovery in 1801, Ceres was later reclassified as an asteroid. But under the new and contrversial planet definition that demoted Pluto, Ceres is now considered a dwarf planet.

Image Credit: Space.com
Vesta, the other target, is irregularly shaped and about 330 miles (530 kilometers) wide-about the size of Arizona.

On July 7, NASA plans to launch Dawn-a mission that had been cancelled but was reistated last year-on a four-year journey to the asteroid belt. The robotic probe will go into orbit around Vesta in 2011 and Ceres in 2015. The new images will help astronomers fine tune mission plans.

The images, released today, were taken with Hubble's Wide Field Planetary Camera 2.

The picture of Vesta allowed astronomers to map the asteroid's southern hemisphere. A crater there, caused by an ancient collision, is a whopping 285 miles (456 kilometers) across. Researchers have known that the collision spawned many smaller asteroids that they call vestoids.

Color differences in the image reflect differences in surface chemicals, some of it possibly due to volcanic activity, that Dawn will explore for clues to the asteroid's interior structure. The effects might be similar to dark "seas" and bright highlands on Earth's moon, astronomers said in a prepared statement.

The pictre of Ceres reveals bright and dark regions that could be topographic features such as craters, researchers said. Or they could just show areas of different surface material.
Ceres' round shape suggests its interior is layered, like Earth's is, astronomers said. It might have a rocky core, an icy mantle and a thin dusty crust. There could be water inside, too.


Original Article: Hubble Photographs Two Asteroids