Stardust will swoop to within about 3,700 miles (6,000 kilometers) of the eastern coast of Africa during the early afternoon local time flyby, a maneuver designed to give it a gravity boost that will increase its relative velocity and place it in a wider orbit around the Sun.

The flyby is expected to take place with little fanfare, unlike the protests that greeted Cassini when it swung past the Earth in 1999 with its 72-pound (32-kilogram) plutonium fuel source in tow.

"Were solar powered, so I dont think anyone knows were coming," said Tom Duxbury, the Stardust project manager at NASAs Jet Propulsion Laboratory (JPL).

Engineers commanded the probe to fire it rockets on Tuesday to change its velocity by 9.2 feet (2.8 meters) per second. An earlier brush with a solar flare which temporarily blinded the robotic spacecraft delayed the rocket-firing maneuver. The spacecraft will perform a similar maneuver on Jan. 5, just 10 days before its Earth encounter.

After the January flyby, the period of time it takes Stardust to orbit the Sun will increase by six months, to 2.5 years. That will place the probe on course to swing past the comet Wild 2 in January 2004 and then back by Earth again two years later.

In 2006, Stardust will jettison to Earth samples of dust and volatiles it has gathered during its flight past Wild 2, as well as minute quantities of interstellar dust collected at various other stages of the mission.

The rocket-firing delay gave flight engineers the opportunity to double up the trajectory correction maneuver with a second bit of spacecraft ballet geared to maximizing the scientific value of the Wild 2 encounter.

Engineers had Stardust turn toward the Sun for approximately 20 minutes on Tuesday, allowing its warming rays to heat a portion of the probes navigation camera.

For more than a year, contaminants have gummed up the camera, obscuring its view and vexing engineers. By heating the cameras components, the mission team hopes to boil off the contaminant.

For more than a week now, and for another few weeks yet, the probe has kept two separate camera heaters on in an effort to drive off more of the frosty contaminant.

"This is the warmest they have been and the warmest we expect they will ever be," Duxbury said of the combined heating and sunbathing effort.

The mission expects to receive star images taken by the camera in late December that will reveal how much the situation has improved. The camera smudging may vanish completely.

"If we're lucky," said Donald Brownlee, Stardust's principal investigator at the University of Washington in Seattle. "If we're not so lucky, it'll stay similar to what we have."

Barely a month later, Stardust will also have a chance to snap some up-close images of the Moon, which should give an indication of any improvement to the cameras spatial resolution. In the images, the Moons disk should fill about half of the cameras field of view, or the same as will Wild 2.

Originally, mission members had hoped Stardust would capture images of Wild 2s nucleus that were 10 times as detailed as those made by the Giotto spacecraft of Comet Halley in 1986. The Giotto images marked the first and only time a spacecraft has spied a comets nucleus.

However, if the present situation holds, Stardust will return images with a resolution perhaps only twice as good as those from Giotto.

"We think we can do the mission okay with the camera as it is. We can do the comet flyby even without the camera. So it's never a life-or-death situation. On the other hand, we'd like to take the best pictures of the comet that we can," Brownlee said.

Following the January flyby, Stardust will then enter a prolonged cruise period, lapping the Sun until its 2004 meeting with Wild 2. However, mission planners still hold out the opportunity that they could encounter Asteroid 5535 Annefrank in November 2002.

The encounter would require the spacecraft to turn its solar panels away from the Sun and rely on battery power. While risky, the encounter would allow spacecraft controllers to hone the skills they will need to help steer the probe to within 90 miles (150 kilometers) of Wild 2 two years later.