CONTOUR Changing Its Attitude July 26, 2002

On July 24, CONTOUR pulled off the first two installments of a six-
part "flop" maneuver designed to gradually aim its onboard rocket for
the critical firing that will boost the spacecraft out of Earth orbit
on Aug. 15. Mission operators had "flipped" CONTOUR shortly after its
July 3 launch for a maneuver that set the timing of its current orbit
around Earth. "Now we’re going back the other way so the solid rocket
motor is pointed in the right direction," says Mark Holdridge,
CONTOUR mission operations manager at the Johns Hopkins Applied
Physics Laboratory.

Each two-hour stage of the flop required more than 1,100 short bursts
from CONTOUR’s thrusters. Mission planners have spread the four
remaining steps over the next 10 days, including them among several
maneuvers to adjust the size and shape of CONTOUR’s orbit.

With each 42-hour loop around Earth – and a lot of help from the
mission team members who design and execute the maneuvers – CONTOUR
slowly moves into the exact position for the "second launch" that
starts it on its path around the Sun and, eventually, toward its
target comets. "The maneuvers are all set up so that you have the
right orbit and you can get to the right point at the right time,"
Holdridge says.