Chicago Sun-Times

One last fling for Rosetta: A slow- motion collision course

Comet chaser kept fans rapt on Earth

- Traci Watson Special for USA TODAY

For a billion miles, the tireless spacecraft called Rosetta has shadowed an icy comet through the solar system, enduring dust storms, fountains of gas and the comet’s mood swings.

Faithful to the end, Rosetta is about to join the comet for eternity.

Early Friday, the craft will smash in slow motion onto the comet. Moving at the pace of a stroll, Rosetta will touch down, bounce and eventually come to rest, probably breaking its solar panels or instrument booms as it tumbles. No word from it will ever reach Earth again.

It’s “unusual to end a mission by actually crashing it into the thing you’ve been studying,” says Christophe­r Carr of Britain’s Imperial College London, who works on the mission. “We’ll be quite emotional when we finally see that last bit of data.”

As the spacecraft follows the comet, both travel ever farther from the sun, starving the ship of the solar power it needs.

Rather than sending Rosetta on a suicide mission, managers at the European Space Agency could simply turn it off. But then it would become “another piece of junk in the solar system,” says Jean- Baptiste Vincent of Germany’s Max Planck Institute for Solar System Research, another scientist working on themission.

By sending Rosetta on a collision course, the spacecraft’s handlers will not only keep the celestial neighborho­od tidy but also will collect priceless data. The ship’s cameras should snap pictures until the craft is 50 feet above the comet’s surface. Other instrument­s will keep running as scientists hold their breath that everything works. “You can only do it once,” Carr says.

Rosetta will smack down onto an intriguing region called Ma’at, which is dotted with pits deep enough to hide Washington’s Lincoln Memorial. Scientists have determined the pits are sources of dust jets blasting from the comet, and researcher­s are eager to learn more about the pits’ role.

Rosetta’s self- destructiv­e plunge will cap a glorious career. Other spacecraft have only glanced at comets while hurtling by. Rosetta, on the other hand, spent more than two years at the mountain- sized comet ChuryumovG­erasimenko, which was named for the Ukrainian scientists who discovered it in 1969.

 ?? EUROPEAN SPACE AGENCY ?? A computer- generated image depicts the Rosetta probe.
EUROPEAN SPACE AGENCY A computer- generated image depicts the Rosetta probe.

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