There are only a few days left until one of the greatest scientific events of our times will unfold. Early on July 4, NASA's Deep Impact probe will try to shoot a comet right in its heart.

If the $333 million mission is successful, the collision will allow scientists to observe and characterize the chemical makeup of the primordial elements that have been preserved inside comets for billions of years.

Deep Impact was launched from Cape Canaveral, Fla., on Jan. 12, and has been set on a course that will intersect Tempel 1 about 83 million miles from Earth. The probe is actually formed out of two separate parts, one that will do the actual blasting, the 39-inch wide impactor and a larger, more capable flyby spacecraft, in charge of taking pictures and analyzing the chemical emissions following the blast.

After separating early July 3, the impactor will rely on its internal guidance system to maneuver itself in front of the speeding comet.

Those maneuvers will enable Tempel 1 to overrun the 800-pound impactor July 4 at 12:52 a.m., colliding with a velocity of 23,000 mph.

Nobody really knows what's going to happen when the probe hits the comet, but all eyes (including Hubble's and those of the astronomers in different observatories on Earth) are set on the comet and on the little probe that is about to make history.