Deep Impact was a NASA space probe launched from Cape Canaveral Air Force Station on January 12, 2005.

Consequently, Deep Impact flew by Earth on December 31, 2007, on its way to an extended mission, designated EPOXI, with a dual purpose to study extrasolar planets and comet Hartley 2 (103P/Hartley).

[3][6] It includes two solar panels, a debris shield, and several science instruments for imaging, infrared spectroscopy, and optical navigation to its destination near the comet.

Its dual purpose was to sense the Impactor's trajectory, which could then be adjusted up to four times between release and impact, and to image the comet from close range.

At its closing velocity of 10.2 km/s, the Impactor's kinetic energy was equivalent to 4.8 tonnes of TNT, considerably more than its actual mass of only 372 kg.

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 entire event was also photographed by Earth-based telescopes and orbital observatories, including Hubble, Chandra, Spitzer, and XMM-Newton.

[19] In 1999, a revised and technologically upgraded mission proposal, dubbed Deep Impact, was accepted and funded as part of NASA's Discovery Program of low-cost spacecraft.

The two spacecraft (Impactor and Flyby) and the three main instruments were built and integrated by Ball Aerospace & Technologies[20] in Boulder, Colorado.

The cause of the problem was simply an incorrect temperature limit in the fault protection logic for the spacecraft's RCS thruster catalyst beds.

Sixty days out was the earliest time that the Deep Impact spacecraft was expected to detect the comet with its MRI camera.

[6] Don Yeomans, a mission co-investigator for JPL pointed out that "it takes 7½ minutes for the signal to get back to Earth, so you cannot joystick this thing.

A 6 m/s (20 ft/s) velocity change was needed to adjust the flight path towards the comet and target the Impactor at a window in space about 100 kilometers (62 mi) wide.

Most of the data captured was stored on board the Flyby spacecraft, which radioed approximately 4,500 images from the HRI, MRI, and ITS cameras to Earth over the next few days.

[21] Don Yeomans confirmed the results for the press, "We hit it just exactly where we wanted to"[38] and JPL Director Charles Elachi stated "The success exceeded our expectations.

[45] Astronomers hypothesized, based on its interior chemistry, that the comet formed in the Uranus and Neptune Oort cloud region of the Solar System.

A comet which forms farther from the Sun is expected to have greater amounts of ices with low freezing temperatures, such as ethane, which was present in Tempel 1.

[46] Because the quality of the images of the crater formed during the Deep Impact collision was not satisfactory, on July 3, 2007, NASA approved the New Exploration of Tempel 1 (or NExT) mission.

However, twenty-four hours before impact, the flight team at JPL began privately expressing a high level of confidence that, barring any unforeseen technical glitches, the spacecraft would intercept Tempel 1.

In the final minutes as the Impactor hit the comet, more than 10,000 people watched the collision on a giant movie screen at Hawaii's Waikīkī Beach.

"[50] Her lawyer asked the public to volunteer to help in the claim by declaring "The impact changed the magnetic properties of the comet, and this could have affected mobile telephony here on Earth.

By contrast, "in China, the public usually has no idea what our scientists are doing, and limited funding for the promotion of science weakens people's enthusiasm for research.

Within 24 hours of the mission's success, a 2-minute music video produced by Martin Lewis had been created using images of the impact itself combined with computer animation of the Deep Impact probe in flight, interspersed with footage of Bill Haley & His Comets performing in 1955 and the surviving original members of The Comets performing in March 2005.

On July 5, 2005, the surviving original members of The Comets (ranging in age from 71–84) performed a free concert for hundreds of employees of the Jet Propulsion Laboratory to help them celebrate the mission's success.

[63] In February 2006, the International Astronomical Union citation that officially named asteroid 79896 Billhaley included a reference to the JPL concert.

On July 21, 2005, Deep Impact executed a trajectory correction maneuver that allows the spacecraft to use Earth's gravity to begin a new mission in a path towards another comet.

[66] However, as the December 2007 Earth gravity assist approached, astronomers were unable to locate Comet Boethin, which may have broken up into pieces too faint to be observed.

[65] EPOXI came within 700 kilometers (430 mi) of the comet, returning detailed photographs of the "peanut" shaped cometary nucleus and several bright jets.

[65] Deep Impact observed Comet Garradd (C/2009 P1) from February 20 to April 8, 2012, using its Medium Resolution Instrument, through a variety of filters.

At the time of re-targeting, whether or not a related science mission would be carried out in 2020 was yet to be determined, based on NASA's budget and the health of the probe.