Exactly one week before the EPOXI probe will pass comet Hartley2, observations of the comet by the Arecibo Planetary Radar have offered scientists a preview, that shows it to be larger than estimated

"It kind of looks like a cross between a bowling pin and a pickle," said EPOXI project manager Tim Larson of NASA's JPL."Only it's about 14 000X larger and hurtling through space at 37km/s." 

Scientists using Arecibo's massive radar dish in Puerto Rico, began observations of Hartley 2 on Oct. 24, just four days after the comet made its closest approach to Earth since its discovery in 1986. (On Oct. 20, the comet came within 17,7 million km of Earth) The observations are scheduled to continue through Friday, Oct. 29.

During the Nov. 4 flyby, the cameras aboard the EPOXI mission spacecraft will get within 700km of the comet.

 "Even without all the data in, we can still make some basic assertions about Hartley 2. Its nucleus is highly elongated and about 2,2km long, and it rotates around itself about once every 18 hours. In addition we now know the size, speed and direction of particles being blown off the comet, and we immediately forwarded all this information to the EPOXI team."

Comet Hartley2 was estimated to be only 600m in diameter, assuming it was a somewhat spherical body

ust what a celestial pickle means for the EPOXI mission remains to be seen. Mission engineers and scientists are discussing the new findings and what – if anything – they signify for the upcoming comet encounter.

The new images are available online at The arecibo radar homepage .