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Weather presents a 40 percent chance of delaying Thursday's 7:20 a.m. launch of NASA's Dawn spacecraft to the asteroid belt to visit the asteroid Vesta and the dwarf planet Ceres.
"We're going to be able to go into orbit around two of the most important bodies in our asteroid belt," said Jim Adams, deputy director of NASA Planetary Sciences Division.
NASA spacecraft normally fly by, then orbit, then bring samples back from an object. Dawn will orbit rocky Vesta and icy Ceres first, saving resources.
"The important thing about Dawn is that it skips that first step," said Adams.
Dawn marks at least three firsts:
1. The first mission to explore the heart of the asteroid belt.
2. The first mission to orbit two celestial bodies outside Earth.
3. The first mission to visit a dwarf planet.
Additionally, Dawn carries the most power solar arrays used on a spacecraft and it has the most powerful ion propulsion system. The spacecraft will be able to generate 11,000 watts of electricity from two 27-foot solar arrays.
The three ion thrusters are ten times more efficient than a traditional rocket engine but require four days to raise the speed by 60 mph, said Marc Rayman, Dawn project systems engineer.
However, by using the estimated five-years worth of thrust in the 937-pound supply of Xenon, the craft will be able to complete its 3.2-billion-mile mission in eight years.
"We're going to be visiting some of the last unexplored worlds in the solar system," said Rayman.
The spacecraft will get an assist from Mars' gravity, as it passes by the red planet and is whipped toward the asteroid belt.
A three-stage Delta II rocket with nine strap-on solid rocket motors will push the spacecraft on its way in just over an hour after launch.
DAWN FACT BOX:
Dimensions: 5.4 feet by 4.2 feet by 5.8 feet
Weight: 2,684 pounds
Power: Two 27-foot by 8 foot solar panels, generating nearly 11 kilowatts
Thrusters: Three ion propulsion thrusters able to work for 2,000 days
Launch vehicle: Delta II Heavy 2925H-9.5, including Star 48 upper stage
Earth-Vesta distance at time of launch: 121 million miles
Vesta arrival: 2011
Ceres arrival: 2015
Total distance traveled: 3.2 billion miles
GOAL OF THE MISSION TO THE ASTEROID BELT:
Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch 4.5 billion years ago by investigating in detail the massive asteroid Vesta and the dwarf planet Ceres, which orbit the sun between Mars and Jupiter in the asteroid belt.
2 comments:
"2. The first mission to orbit two celestial bodies."
Should stress outside of Earth as they pointed out.
NASA the last launch of a Delta ll
launch vehicle, will be oct 2008 save this Program JCW
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