Blog Archive

Sunday, July 17, 2011

Dawn spacecraft to study origins of Earth

NASA's Dawn robotic science probe has entered the orbit around the asteroid Vesta to study the second most massive of its kind in the solar system.

This unmanned NASA probe made history 117 million miles from Earth on Saturday (July 16) when it arrived at the huge asteroid Vesta, making it the first spacecraft ever to orbit an object in the solar system's asteroid belt.

Dawn, which was launched in 2007 by the US space agency, is to offer insights into the beginning of the universe by examining rocky objects that date to the time when planets were forming in the solar system.

The 1.6—metre—long, 747—kilogramme craft was to have begun circling the asteroid Vesta early Saturday. Both Vesta and another Dawn target, the dwarf planet Ceres, are significantly smaller than Earth’s moon.

The probe has taken four years to get to Vesta and will spend the next year studying the huge rock before moving on to the "dwarf planet" Ceres.

Vesta is a huge asteroid about as wide as U.S. state of Arizona, and is also the brightest asteroid in the solar system. It is located in the asteroid belt, a band of rocky objects that encircles the sun between the orbits of Mars and Jupiter.

Asteroid Vesta looks like a punctured football, the result of a colossal collision sometime in its past that knocked off its south polar region.

Using ion thrusters to propel it through interplanetary space, the spacecraft has been sneaking up on Vesta, rather than speeding up and rapidly slowing down. The latter method used by rocket-propeled spacecraft can have catastrophic consequences if the target should be missed. With Dawn's ion drive, if the target is missed, there would have been enough fuel to take another shot at entering orbit.

Interestingly, as the exact mass (and therefore gravity) of Vesta is not known, the exact time of orbital capture cannot be calculated. If the asteroid is more massive, Dawn would have been captured sooner by a stronger gravitational field; if Vesta is less massive, the spacecraft would be captured later by a weaker gravitational field. Until more data is relayed from Dawn, we won't know the precise time of capture.

No comments:

Post a Comment

Total Pageviews