On this day July 4, 2005
The NASA space probe Deep Impact impacted the nucleus of the comet Tempel 1, excavating debris from its interior to study its composition.
The probe launched on January 12, 2005 was designed to study the composition of the interior of the comet 9P/Tempel by colliding a section of the spacecraft into the comet.
At 5:52 UTC on July 4, 2005, the impactor of the Deep Impact probe successfully impacted the comet’s nucleus, excavating debris from the interior of the nucleus.
Photographs of the impact showed the comet to be more dusty and less icy than expected. The impact generated a large, bright dust cloud that obscured the hoped-for view of the impact crater.
Previous space missions to comets, such as Giotto and Stardust, were fly-by missions, only able to photograph and examine the surfaces of cometary nuclei from a distance.
The Deep Impact mission was the first to eject material from a comet’s surface. The mission garnered large publicity from the media, international scientists, and amateur astronomers.
After the completion of its prime mission, proposals were made to utilize the spacecraft further. Consequently, Deep Impact flew by Earth on December 31, 2007 on its way to an extended mission called EPOXI with a dual purpose to study extrasolar planets and comet Hartley 2.