page_title: Deep Impact (spacecraft)
section_title: Mission profile
hierarchical_section_title: Deep Impact (spacecraft) / Mission profile
caption_attribution_description: original description: At Ball Aerospace in Boulder, Colo., a thermal vacuum test is conducted on Deep Impact instruments in the instrument assembly area in the Fisher Assembly building clean room. The High Resolution Instrument (HRI, at right) is one of the largest space-based instruments built specifically for planetary science. It is the main science camera for Deep Impact, providing the highest resolution images via a combined visible camera, an infrared spectrometer and a special imaging module. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impact’s flyby spacecraft will collect pictures and data of how the crater forms, measuring the crater’s depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.
context_page_description: Deep Impact was a NASA space probe launched from Cape Canaveral Air Force Station on January 12, 2005. It was designed to study the interior composition of the comet Tempel 1, by releasing an impactor into the comet. At 05:52 UTC on July 4, 2005, the Impactor successfully collided with the comet's nucleus. The impact excavated debris from the interior of the nucleus, forming an impact crater. Photographs taken by the spacecraft showed the comet to be more dusty and less icy than had been expected. The impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater.
  Previous space missions to comets, such as Giotto, Deep Space 1, and Stardust, were fly-by missions. These missions were able to photograph and examine only the surfaces of cometary nuclei, and even then from considerable distances. The Deep Impact mission was the first to eject material from a comet's surface, and the mission garnered considerable publicity from the media, international scientists, and amateur astronomers alike.
  Upon the completion of its primary mission, proposals were made to further utilize the spacecraft.
context_section_description: Following its launch from Cape Canaveral Air Force Station pad SLC-17B at 18:47 UTC on January 12, 2005, the Deep Impact spacecraft traveled 429 million km (267 million mi) in 174 days to reach comet Tempel 1 at a cruising speed of 28.6 km/s (103,000 km/h; 64,000 mph). Once the spacecraft reached the vicinity of the comet on July 3, 2005, it separated into the Impactor and Flyby sections. The Impactor used its thrusters to move into the path of the comet, impacting 24 hours later at a relative speed of 10.3 km/s (37,000 km/h; 23,000 mph). The Impactor delivered 1.96×10¹⁰ joules of kinetic energy—the equivalent of 4.7 tons of TNT. Scientists believed that the energy of the high-velocity collision would be sufficient to excavate a crater up to 100 m (330 ft) wide, larger than the bowl of the Roman Colosseum. The size of the crater was still not known one year after the impact.  The 2007 Stardust spacecraft's NExT mission determined the crater's diameter to be 150 meters (490 ft).
  Just minutes after the impact, the Flyby probe passed by the nucleus at a close distance of 500 km (310 mi), taking pictures of the crater position, the ejecta plume, and the entire cometary nucleus. The entire event was also photographed by Earth-based telescopes and orbital observatories, including Hubble, Chandra, Spitzer, and XMM-Newton. The impact was also observed by cameras and spectroscopes on board Europe's Rosetta spacecraft, which was about 80 million km (50 million mi) from the comet at the time of impact. Rosetta determined the composition of the gas and dust cloud that was kicked up by the impact.
caption: Cameras of the Flyby spacecraft, HRI at right, MRI at left
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