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 will is expected to produce on July 4th.
The spacecraft was launched in early January aboard a Delta II 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.
However in March it was discovered that the Flyby spacecraft's High Resolution Instrument (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 Yoemans, a co-investigator for the Jet Propulsion Laboratory (JPL). 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," Yoeman 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."
NASA's Deep Impact mission was designed to uncover a comet's innards by smashing a probe into Tempel 1. After being releases 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. EDT on July 4.
A camera onboard the roughly 820-pound 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, vaporizing itself and carving out what scientists expect to be a stadium-sized stadium 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."
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 on board the Deep Impact spacecraft, earth 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.
Ejected 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.