The Dawn spacecraft begins its trek to the asteroid belt

A NASA probe exploded into space early Thursday, launching an unprecedented mission to explore the two largest asteroids in the solar system.

Riding on opa’s Delta 2 rocket, NASA’s sDawn spacecraft launched to asteroids Vesta and Ceres at 7:34 a.m. EDT (1134 GMT) from Cape Canaveral Air Force Station in Cape Canaveral, Kenya. Florida.

“In my opinion, we are going to visit some of the last unexplored worlds in the solar system,” he added. said Marc Rayman, director of system engineering for Dawn at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

The eight-year Dawn mission will carry the 2,685-pound (1,212-kilogram) probe three billion miles (4.9 billion kilometers) on NASA’s first spacewalk deep into the asteroid belt, a ring of space rocks that circle the Sun between the orbits of Mars and Jupiter.

By visiting the bright, rocky asteroid Vesta and the great, icy Ceres, researchers hope Dawn will shed new light on planet formation and the early evolution of the solar system.

Aside from a temperamental ship, which delayed today’s launch by 14 minutes when it encroached on Atlantis Ocean’s splash zone for segments of Dawn’s rocket, liftoff went smoothly. as planned, said NASA Launch Director Omar Baez.

Long journey ahead

Dawn is expected to meet and orbit the 330-mile (530-kilometer) wide Vesta between August 2011 and May 2012, then move to Texas-sized Ceres by February 2015. With its spherical shape and diameter At 585 miles (942 kilometers), Ceres is so large that it is also considered a dwarf planet.

“It will be the first mission to travel and orbit two celestial bodies, and the first to visit a dwarf planet.” said Dawn program manager Jim Adams at NASA Headquarters in Washington, DC, of ​​the flight to the asteroid.

Dawn carries an optical camera, a gamma-ray and neutron detector, and a mapping spectrometer to study Vesta and Ceres. Some of these tools will be tested during a planned flyby of Mars in 2009, researchers said.

To power these instruments, the spacecraft is also equipped with the most powerful solar arrays ever launched into deep space.

With a wingspan of nearly 65 feet (nearly 20 meters), or about the distance from the pitcher’s mound to home plate on a baseball diamond, the arrays will generate more than 10 kilowatts near Earth, although that power is diminishing. as the spacecraft moves away from the Sun.

NASA officials pegged Dawn’s mission cost at $357.5 million, excluding the cost of its Delta 2 rocket, according to a September update. In a July briefing, Dawnresearchers said the flight to the asteroid could cost a total of $449 million and incur an additional $25 million in overhead due to launch delays.

Attempts to launch the mission in July were thwarted first by bad weather and rocket problems, then by difficulties in arranging ship and aircraft tracking equipment in time for liftoff. NASA also canceled the mission outright in March 2006, only to reinstate the expedition a few weeks later.

“It’s been an emotional roller coaster,” he added. Chris Russell, Dawn’s principal investigator at the University of California, Los Angeles, said of the mission. “And part of the emotional roller coaster is the gratitude we have for all the people who stood up for Dawn during this time.”

Anasteroid Hike on Ion Energy

Built by Virginia-based Orbital Sciences, the Dawn spacecraft has been touted as the Prius of space probes due to the incredible power efficiency of its three-motor ion drive.

Dawn carries 937 pounds (425 kilograms) of xenon gas, which it gives an electrical charge to create ions which are then catapulted out of its engines at nearly 90,000 miles per hour (144,840 km/h). Over time, the ion thrust builds up and allows Dawn to alter her flight path to first rendezvous and then orbit multiple targets like Vesta and Ceres without requiring huge amounts of fuel from conventional rocket.

?The first time I heard of ion propulsion was in a ?Star Trek? episode,? said Rayman, adding that such engines are also touted to power TIE fighters? or TwinIon Engine – from? Star Wars? notoriety. “Dawn makes the TIE fighter better because it has three ion engines.”

While it will take Dawn four days to go from zero to 60 miles per hour (96 km/h), the probe will gradually accelerate by firing its ion engine non-stop for the next six years, NASA said. adding that the mission is the agency? s first operational scientific expedition powered by ion propulsion.

“That would make it the longest powered flight in space history,” he added. said Keyur Patel, NASA’s Dawn project manager at JPL, just before liftoff.

Each of the three ion engines weighs about 20 pounds (nine kilograms) and is about the size of a basketball.

“From such a small engine, you can get this blue rocket exhaust beam shooting out at 89,000 miles per hour,” Patel said ahead of launch day. “It’s a remarkable system.”

NASA will host a post-launch briefing on Dawn’s mission to the asteroid at 1:00 p.m. EDT (17:00 GMT) on NASA TV.

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