Comet Close Encounter Set for Valentine's Night

Scientists and technicians in Australia and the United States are making final preparations for tomorrow afternoon's close encounter with Comet Tempel 1.

The Canberra Deep Space Communication Complex (CDSCC) will be NASA's primary receiving station for the flyby, set to occur at 11:37 pm EST.

CDSCC spokesperson Glen Nagle says the Stardust spacecraft has been closing in on the comet at a rate of 950 thousand kilometers a day, and everyone is ready for the event.

"The spacecraft will take 72 images with confirmation expected 19 minutes after the intercept," said Nagle. "Once we get the spacecraft signal, it'll be relayed to mission control at the Jet Propulsion Laboratory in Pasadena, California."

Nagel says it will be the first time scientists have been able to study the same comet twice.

"Tempel 1 was visited by NASA's Deep Impact mission in 2005. The spacecraft fired a washing machine-sized copper projectile at the comet to see what happens." Stardust was launched in 1999, and seven years later intercepted Comet Wild 2, becoming the first spacecraft to collect samples from a comet and bring them back to Earth.

After completing the mission in 2006, Nagle says the spacecraft was renamed Stardust-NExT (New Exploration of Tempel) and sent to intercept Tempel 1.

"The spacecraft is in good health despite not being designed to undertake this new mission," he said. "There were initial targeting issues and the lack of a super high resolution camera for the flyby was a concern.

"But there's a good navigation camera, and the spacecraft will be flying less than 200 kilometers above the comet's surface."

Nagle says, scientists will use the images collected by Stardust to understand how Tempel 1 has changed since Deep Impact's encounter six years ago.

"Stardust will tell them about the exterior of the comet, the structure of the surface, how solid it really is and hopefully get images of the Deep Impact crater," he said.

According to Nagle, the impact in 2005 threw up so much ejecta, scientists were unable to see how big the resulting crater was, or how much damage it caused to the comet's surface.

He says researchers also want to see how comets degrade over time as they journey through the solar system, and see if there have been any changes to the comet's tumble and orbit.

"That would be useful for future studies of comets, especially any that might be coming our way."

"Deep Impact confirmed comets are big dirty snowballs with highly volatile gases which burn off as they get closer to the sun. And they contain interesting organic chemistry like amino acids, which are the building blocks of life."

NASA TV will video stream the encounter live.