Dawn's Smooth Move

[n2doc]

August 1, 2011: When a NASA spacecraft goes into orbit around a new world for the first time, the control room is usually packed to capacity with scientists, engineers, and dignitaries ready to leap and shout when the retro-rockets fire. It's a big, noisy event.

July 15, 2011, was one of those days. NASA's Dawn spacecraft approached Vesta and became the first probe from Earth to orbit a main belt asteroid. Dawn's cameras revealed a desolate world of transcendent beauty, thrilling everyone who worked on the project.
Needless to say, the control room was .... silent?

"Actually it was empty," says Dawn Chief Engineer Marc Rayman of JPL. "Dawn entered orbit on a Friday night; I myself was out dancing with my wife and friends."

What gives? Rayman, an avid folk dancer, explains: "Our mission has a unique choreography."

Indeed, Dawn has its own way of doing things. While most spacecraft blast off Earth atop a firestorm of conventional rocket exhaust, then coast to their destinations with engines turned off to conserve fuel, Dawn was able to continue thrusting throughout its voyage. Fuel-efficient ion engines gently propelled the spacecraft toward Vesta for more than three years, never exerting more force than the weight of a feather held in your open palm yet, over time, gathering enough speed to catch an asteroid racing halfway across the solar system.

more
http://science.nasa.gov/science-news/science-at-nasa/2011/01aug_smoothmove/