Image: Deep Impact
Deep Impact's Flyby spacecraft (right foreground) sends out the Impactor (middle) toward Comet Tempel 1 (left, far background) in this artist's conception. The High Resolution Imager is the gold-colored telescope at the bottom of Flyby, pointing toward the comet.
updated 6/9/2005 5:26:30 PM ET 2005-06-09T21:26:30

The scientists behind NASA’s Deep Impact mission said Thursday they hope to fix the spacecraft’s blurry vision by using a mathematical process on the images it captures after they have been transmitted to Earth.

The announcement was made at a press briefing at NASA Headquarters in Washington, during which the Deep Impact team discussed the special fireworks show the mission is expected to produce on the Fourth of July.

The spacecraft was launched in early January aboard a Delta 2 rocket, and is scheduled to rendezvous with Comet Tempel 1 early next month. Twenty-four hours before contact, the spacecraft’s two main parts — Flyby and Impactor — will separate and take part in a very carefully orchestrated hit-and-run.

Compensating for poor focus
In March, it was discovered that the Flyby spacecraft's High Resolution Instrument, or HRI, was not focusing properly. The team will use a process called deconvolution to remedy the situation. Deconvolution is widely used in image processing and involves the reversal of the distortion created by the faulty lens of a camera or other optical devices, like a telescope or microscope.

"The process is a purely mathematical manipulation that works extremely well,” said Don Yeomans, a co-investigator for the Jet Propulsion Laboratory in Pasadena, Calif. JPL is managing the mission for NASA.

“Even if you have a perfect telescope, which is limited by diffraction, you can use deconvolution to improve the resolution,” Yeomans said. “The process is sometimes time-consuming, so the biggest effect on the science is a delay while you do all the processing to get the quality that you expected."

What Deep Impact will do
NASA’s Deep Impact mission is designed to uncover a comet’s innards by smashing a probe into Tempel 1. After being released from the Flyby craft, the Impactor will position itself directly in front of the speeding comet for a head-on collision. The impact is schedule to occur at 1:52 a.m. ET on July 4.

A camera onboard the 820-pound (372-kilogram) copper Impactor probe will capture rare and intimate close-ups of Tempel 1’s nucleus right up to the moment of impact. The probe will slam into Tempel 1 at 23,000 miles per hour (36,800 kilometers per hour), vaporizing itself and carving out what scientists expect to be a stadium-sized crater in the side of the comet.

As Impactor prepares for its kamikaze dive, Flyby will arc around and position itself for a ringside view of the explosive wallop that Impactor is expected to deal to Tempel 1.

“It’s utterly simple experiment in concept,” said Michael A’Hearn, the mission’s principal investigator. “You have something that you put in front of a comet and let the comet run over it — it’s like putting penny in front of a train track.”

Technical difficulties
Technically, however, it will be very difficult to do. Rick Grammier, Deep Impact’s project manager at Jet Propulsion Laboratory, described the mission this way:

“[It’s like] a bullet trying to hit a second bullet, with a third bullet in the right place at the right time trying to watching the first two bullets and trying to gather the scientific data from that impact.”

In addition to the cameras onboard the Deep Impact spacecrafts, Earth-based and space-based telescopes will also have their eyes trained on the impact. Virtually every aspect of the blast — everything from the size and shape of the crater to the angle at which material is spewed into space — is expected to yield valuable clues about the makeup and nature of the comet’s mysterious nucleus.

Material spewed from the Tempel 1 will combine with the dense halo of material that continually surrounds the comet when it is near the sun, causing it to dramatically brighten for a brief moment, panelists explained.

Comets are believed to be remnants from very birth of solar system, and their interiors are believed to contain pristine material that is billions of years old.

“They hold the keys to the birth of the solar system and perhaps to life itself” said Yeomans, referring to the theory that comets may have actually brought water and organic material to Earth.

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