.gif)
Deep Impact (space mission)
Encyclopedia
Deep Impact is a NASA
space probe
launched on January 12, 2005. It was designed to study the composition of the comet
interior of 9P/Tempel
, by releasing an impactor into the comet. At 5:52 UTC on July 4, 2005, the impactor successfully collided with the comet's nucleus
. The impact excavated debris from the interior of the nucleus, allowing photographs of the impact crater. The photographs showed the comet to be more dusty and less icy than had been expected. The impact generated a large and bright dust cloud, which unexpectedly obscured the view of the impact crater.
Previous space missions to comets, such as Giotto
and Stardust
, were fly-by missions. These missions were 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, and the mission garnered large publicity from the media, international scientists, and amateur astronomers.
Upon the completion of its primary mission, proposals were made to further utilize the spacecraft. 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 planet
s and comet Hartley 2
.
The mission's Principal Investigator was Michael A'Hearn
, an astronomer at the University of Maryland
. He led the science team, which included members from Cornell University
, University of Maryland, University of Arizona
, Brown University
, Belton Space Exploration Initiatives, JPL, University of Hawaii
, SAIC
, Ball Aerospace
, and Max-Planck-Institut für extraterrestrische Physik.
The spacecraft
consists of two main sections, the 370-kg (815-lb) copper-core "Smart Impactor" that impacted the comet, and the "Flyby" section, which imaged the comet from a safe distance during the encounter with Tempel 1.
The Flyby spacecraft is about 3.2 meters (10.5 ft) long, 1.7 meters (5.6 ft) wide and 2.3 meters (7.5 ft) high. 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. The spacecraft also carried two cameras, the High Resolution Imager (HRI), and the Medium Resolution Imager (MRI). The HRI is an imaging device that combines a visible-light camera with a filter wheel, and an imaging infrared
spectrometer
called the "Spectral Imaging Module" or SIM that operates on a spectral band from 1.05 to 4.8 micrometres. It has been optimized for observing the comet's nucleus. The MRI is the backup device, and was used primarily for navigation during the final 10-day approach. It also has a filter wheel, with a slightly different set of filters.
The Impactor section of the spacecraft contains an instrument that is optically identical to the MRI, called the Impactor Targeting Sensor (ITS), but without the filter wheel. 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. As the Impactor neared the comet's surface, this camera took high-resolution pictures of the nucleus (as good as 0.2 metres (7.9 in) per pixel
) that were transmitted in real-time to the Flyby spacecraft before it and the Impactor were destroyed. The final image taken by the impactor was snapped only 3.7 seconds before impact.
The impactor's payload, dubbed the "Cratering Mass", was 100% copper (impactor 49% copper by mass) to reduce debris interfering with scientific measurements of the impact. Since copper was not expected to be found on a comet, scientists could eliminate copper from the spectrometer reading. Instead of using explosives, it was also cheaper to use copper as the payload.
The name of the mission is shared with the 1998 Deep Impact
film, in which a comet strikes the Earth. This is coincidental, however, as the scientists behind the mission and the creators of the film devised the name independently of each other at around the same time.
_rocket_with_deep_impact.jpg)
Following its launch on January 12, 2005, the Deep Impact spacecraft traveled 429 million kilometers (267 million mi) in 174 days to reach comet 9P/Tempel at a cruising speed of 28.6 km/s (103,000 km/h or 64,000 mph). Once the spacecraft reached the vicinity of the comet on July 3, 2005, it separated into two portions, an impactor and a flyby probe. 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 or 23,000 mph). The impactor, a 370-kilogram (820-pound) copper projectile, delivered 1.96 × 1010 joule
s of kinetic energy
—the equivalent of 4.7 ton
s of TNT. Scientists believed that the energy of the high-velocity collision would be sufficient to excavate a crater up to 100 m (328 ft) wide (larger than the bowl of the Roman Colosseum
). The size of the crater was still not known one year after the impact.
Just minutes after the impact, the flyby probe passed by the nucleus at a close distance of 500 km (310.7 mi), taking pictures of the crater position, the ejecta plume, and the entire cometary nucleus. The entire event was photographed by Earth-based telescope
s and orbital observatories
, including the 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.
A comet-impact mission was first proposed to NASA in 1996, but at the time, NASA engineers were skeptical that the target could be hit. 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 Corp. in Boulder, Colorado
. Developing the software for the spacecraft took 18 months and the application code consisted of 20,000 lines and 19 different application threads. The total cost of developing the spacecraft and completing its mission reached US$330 million.
on January 12, 2005 at 1:47 pm EST (1847 UTC) by a Delta 2 rocket.
Deep Impacts state of health was uncertain during the first day after launch. Shortly after entering orbit around the Sun and deploying its solar panels, the probe switched itself to safe mode
. The cause of the problem was simply an incorrect temperature limit in the fault protection logic for the spacecraft's RCS thruster catalyst beds. The spacecraft's thrusters were used to detumble the spacecraft following third stage separation. NASA subsequently announced that the probe was out of safe mode and healthy.
On February 11, Deep Impacts rockets were fired as planned to correct the spacecraft's course. This correction was so precise that the next planned maneuver for March 31 was canceled. The "commissioning phase" verified that all instruments were activated and checked out. During these tests it was found that the HRI images were not in focus after it underwent a bake-out period. After mission members investigated the problem, on June 9, it was announced that by using image processing software and the mathematical technique of deconvolution, the HRI images could be corrected to restore much of the resolution anticipated.
The "cruise phase" began on March 25, immediately after the commissioning phase was completed. This phase continued until about 60 days before the encounter with comet 9P/Tempel. On April 25 the probe acquired the first image of its target at a distance of 64 million km (40 million miles).
On May 4 the spacecraft executed its second trajectory correction maneuver. Burning its rocket engine for 95 seconds, the spacecraft speed was changed by 18.2 km/h (11.3 mph). Rick Grammier, the project manager for the mission at NASA's Jet Propulsion Laboratory, reacted to the maneuver stating that "spacecraft performance has been excellent, and this burn was no different...it was a textbook maneuver that placed us right on the money."
encounter. Sixty days out was the earliest time that the Deep Impact spacecraft was expected to detect the comet with its MRI camera. In fact, the comet was spotted ahead of schedule, 69 days before impact (see Cruise phase above). This milestone marks the beginning of an intensive period of observations to refine knowledge of the comet's orbit and study the comet's rotation, activity, and dust environment.
On June 14 and June 22, Deep Impact observed two outbursts of activity from the comet, the latter being six times larger than the former. The spacecraft studied the images of various distant stars to determine its current trajectory and position. 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. You have to rely on the fact that the Impactor is a smart spacecraft as is the Flyby spacecraft. So you have to build in the intelligence ahead of time and let it do its thing." On June 23, the first of the two final trajectory correct maneuvers (targeting maneuver) was successfully executed. A 6 m/s (13.4 mph) velocity change was needed to adjust the flight path towards the comet and target the impactor at a window in space about 100 kilometres (62.1 mi) wide.
Impact phase began nominally on June 29, five days before impact. The impactor successfully separated from the flyby spacecraft at 6:00 (6:07 Ground UTC) July 3 UTC. The first images from the instrumented Impactor were seen two hours after separation.
The flyby spacecraft performed one of two divert maneuvers to avoid damage. A 14-minute burn was executed which slowed down the spacecraft. It was also reported that the communication link between the flyby and the impactor was functioning as expected. The impactor spacecraft executed three correction maneuvers in the final two hours before impact.
The impactor was maneuvered to plant itself in front of the comet, so that 9P/Tempel would collide with it. Impact occurred at 05:45 UTC (05:52 Ground UTC, +/- up to three minutes, one-way light time = 7m 26s) on the morning of July 4, within one second of the expected time for impact.
The impactor returned images as late as three seconds before impact. 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. The energy from the collision was similar in size to exploding five tons of dynamite
and the comet shone six times brighter than normal.
Impact Phase Timeline (NASA)
Mission control did not become aware of the impactor's success until five minutes later at 0157 ET
. Once news of a successful impact had taken place, the mission control team members applauded and hugged each other. Don Yeomans confirmed the results for the press, "We hit it just exactly where we wanted to" and JPL Director Charles Elachi stated "The success exceeded our expectations."
In the post-impact briefing at 0100 Pacific Daylight Time (08:00 UTC) on July 4, 2005, the first processed images revealed existing craters
on the comet. NASA scientists stated they could not see the new crater that had formed from the impactor, but it was later discovered to be about 100 meters (328 ft) wide and up to 30 meters (98 ft) deep. Lucy McFadden, one of the co-investigators of the impact, stated "We didn't expect the success of one part of the mission [bright dust cloud] to affect a second part [seeing the resultant crater]. But that is part of the fun of science, to meet with the unexpected." Analysis of data from the Swift X-ray telescope
showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of 5 million kilograms (11 million pounds) of water and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact.
Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous models which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to talcum powder rather than sand
. Other materials found while studying the impact included clay
s, carbonate
s, sodium
, and crystalline silicate
s which were found by studying the spectroscopy of the impact. Clays and carbonates usually require liquid water to form and sodium is rare in space. Observations also revealed that the comet was about 75% empty space, and one astronomer compared the outer layers of the comet to the same makeup of a snow bank. Astronomers have expressed interest in more missions to different comets to determine if they share similar compositions or if there are different materials found deeper within comets that were produced at the time of the solar system's formation.
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 9P/Tempel. Astronomers believe that other comets with compositions similar to Tempel 1 are likely to have formed in the same region.
, which had studied Comet Wild 2 in 2004. Stardust was placed into a new orbit so that it approached Tempel 1 at a distance of approximately 200 km (124.3 mi) on February 15, 2011, 04:42 UTC. This was the first time that a comet was visited twice, and provided an opportunity to better observe the crater that was created by Deep Impact as well as observing the changes caused by the comet’s latest close approach to the Sun.
On February 15, NASA scientists identified the crater formed by Deep Impact in images from Stardust. The crater is estimated to be 150 meters (500 ft) in diameter, and has a bright mound in the center likely created when material from the impact fell back into the crater.http://www.nasa.gov/mission_pages/stardust/multimedia/Schultz4.html
The impact was a substantial news event reported and discussed online, in print, and on television. There was a genuine suspense because experts held widely differing opinions over the result of the impact. Various experts debated whether the impactor would go straight through the comet and out the other side, would create an impact crater, would open up a hole in the interior of the comet, and other theories. 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 9P/Tempel. One senior personnel member stated "All we can do now is sit back and wait. Everything we can technically do to ensure impact has been done." 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 Waikiki Beach
.
Experts came up with a range of soundbites to summarize the mission to the public. Iwan Williams of Queen Mary, University of London
, said "It was like a mosquito hitting a 747
. What we've found is that the mosquito didn't splat on the surface; it's actually gone through the windscreen."
One day after the impact Marina Bay, a Russian astrologer
, sued NASA for $300 million for the impact which "ruin[ed] the natural balance of forces in the universe." 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. If your phone went down this morning, ask yourself Why? and then get in touch with us." On August 9, 2005 the Presnensky Court of Moscow ruled against Bay, although she did attempt to appeal the result. One Russian physicist said that the impact had no effect on Earth and "the change to the orbit of the comet after the collision was only about 10 cm (3.9 in)."
The mission was notable for one of its promotional activities, "Send Your Name To A Comet!". Visitors to the Jet Propulsion Laboratory
's website were invited to submit their name between May 2003 and January 2004, and the names gathered—some 625,000 in all—were then burnt onto a mini-CD, which was attached to the impactor. Dr. Don Yeomans, a member of the spacecraft's scientific team, stated "this is an opportunity to become part of an extraordinary space mission ... when the craft is launched in December 2004, yours and the names of your loved-ones can hitch along for the ride and be part of what may be the best space fireworks show in history." The idea was credited with driving interest in the mission.
Two days after the U.S. mission succeeded in having a probe collide with a comet, China revealed a plan for what it called a "more clever" version of the mission: landing a probe on a small comet or asteroid
to push it off course. China will begin the mission after sending a probe to the Moon
.
Since observing time on large, professional telescopes such as Keck or Hubble is always scarce, the Deep Impact scientists called upon "advanced amateur, student, and professional astronomers" to use small telescopes to make long-term observations of the target comet before and after impact. The purpose of these observations was to look for "volatile outgassing, dust coma development and dust production rates, dust tail development, and jet activity and outbursts." By mid-2007, amateur astronomers had submitted over a thousand CCD
images of the comet.
One notable amateur observation was by students from schools in Hawaii, working with US and UK scientists, who during the press conference took live images using the Faulkes Automatic Telescope
in Hawaii (the students operated the telescope over the Internet) and were one of the first groups to get images of the impact. One amateur astronomer reported seeing a structureless bright cloud around the comet, and an estimated magnitude
2 increase in brightness after the impact. Another amateur published a map of the crash area from NASA images.
" by Bill Haley and His Comets becoming the first rock and roll
single to reach No. 1 on the recording sales charts. Within twenty-four hours of the mission's success, a two-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 and His Comets performing in 1955 and the surviving original members of The Comets performing in March 2005. The video was posted to NASA's website for a couple of weeks afterwards.
On July 5, the surviving original members of The Comets (ranging in age from 71 to 84) performed a free concert for hundreds of employees of the Jet Propulsion Laboratory to help them celebrate the mission's success. This event received worldwide press attention. Later, in February 2006, the International Astronomical Union
citation that officially named asteroid 79896 Billhaley
included a reference to the JPL concert.
The original plan was for a December 5, 2008 flyby of Comet Boethin
, coming within 700 kilometres (435 mi) of the comet. Michael A'Hearn, the Deep Impact team leader, explained "We propose to direct the spacecraft for a flyby of Comet Boethin to investigate whether the results found at Comet Tempel 1 are unique or are also found on other comets." The $40 million mission would provide about half of the information as the collision of Tempel 1 but at a fraction of the cost. Deep Impact would use its spectrometer to study the comet's surface composition and its telescope for viewing the surface features.
However, as the Earth gravity assist approached, astronomers were unable to locate Comet Boethin, which may have broken up into pieces too faint to be observed. Consequently, its orbit could not be calculated with sufficient precision to permit a flyby.
(Hartley 2). However, this would require an extra two years of travel for Deep Impact. On May 28, 2010, a burn of 11.3 seconds was conducted, to enable the June 27 Earth fly-by to be optimized for the transit to Hartley 2 and fly-by on November 4. The velocity change was 0.1 metre per second (0.22369362920544 mph).
On November 4, 2010, the Deep Impact extended mission (EPOXI) returned images from comet Hartley 2. EPOXI came within 700 kilometres (435 mi) of the comet, returning detailed photographs of the "peanut" shaped cometary nucleus and several bright jets. The probe's medium-resolution instrument captured the photographs.
Additional information
Maps, photos, and other images
Other languages
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
launched on January 12, 2005. It was designed to study the composition of the comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
interior of 9P/Tempel
9P/Tempel
Tempel 1 , is a periodic comet discovered by Wilhelm Tempel in 1867. It currently completes an orbit of the Sun every 5.5 years. Tempel 1 was the target of the Deep Impact space mission, which photographed a deliberate high-speed impact upon the comet in 2005...
, by releasing an impactor into the comet. At 5:52 UTC on July 4, 2005, the impactor successfully collided with the comet's nucleus
Comet nucleus
The nucleus is the solid, central part of a comet, popularly termed a dirty snowball. A cometary nucleus is composed of rock, dust, and frozen gases. When heated by the Sun, the gases sublimate and produce an atmosphere surrounding the nucleus known as the coma...
. The impact excavated debris from the interior of the nucleus, allowing photographs of the impact crater. The photographs showed the comet to be more dusty and less icy than had been expected. The impact generated a large and bright dust cloud, which unexpectedly obscured the view of the impact crater.
Previous space missions to comets, such as Giotto
Giotto mission
Giotto was a European robotic spacecraft mission from the European Space Agency, intended to fly by and study Halley's Comet. On 13 March 1986, the mission succeeded in approaching Halley's nucleus at a distance of 596 kilometers....
and Stardust
Stardust (spacecraft)
Stardust is a 300-kilogram robotic space probe launched by NASA on February 7, 1999 to study the asteroid 5535 Annefrank and collect samples from the coma of comet Wild 2. The primary mission was completed January 15, 2006, when the sample return capsule returned to Earth...
, were fly-by missions. These missions were 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, and the mission garnered large publicity from the media, international scientists, and amateur astronomers.
Upon the completion of its primary mission, proposals were made to further utilize the spacecraft. Consequently, Deep Impact flew by Earth on December 31, 2007 on its way to an extended mission, designated EPOXI
EPOXI
EPOXI is a NASA unmanned space mission led by the University of Maryland using the existing Deep Impact vehicle to begin a new series of observations. It first investigated extrasolar planets and, on November 4, 2010, it performed a close approach to the comet 103P/Hartley...
, with a dual purpose to study extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
s and comet Hartley 2
103P/Hartley
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia...
.
Scientific goals
The Deep Impact mission was planned to help answer fundamental questions about comets, which included what makes up the composition of the comet's nucleus, what depth the crater would reach from the impact, and where the comet originated in its formation. By observing the composition of the comet, astronomers hoped to determine how comets form based on the differences between the interior and exterior makeup of the comet. Observations of the impact and its aftermath would allow astronomers to attempt to determine the answers to these questions.The mission's Principal Investigator was Michael A'Hearn
Michael A'Hearn
Michael F. A'Hearn is an astronomer and professor at the University of Maryland who is the principal investigator for the NASA EPOXI mission. He was the principal investigator for the NASA Deep Impact mission. He received his bachelors in science at Boston College and his Ph. D in Astronomy at the...
, an astronomer at the University of Maryland
University of Maryland, College Park
The University of Maryland, College Park is a top-ranked public research university located in the city of College Park in Prince George's County, Maryland, just outside Washington, D.C...
. He led the science team, which included members from Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
, University of Maryland, University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...
, Brown University
Brown University
Brown University is a private, Ivy League university located in Providence, Rhode Island, United States. Founded in 1764 prior to American independence from the British Empire as the College in the English Colony of Rhode Island and Providence Plantations early in the reign of King George III ,...
, Belton Space Exploration Initiatives, JPL, University of Hawaii
University of Hawaii
The University of Hawaii System, formally the University of Hawaii and popularly known as UH, is a public, co-educational college and university system that confers associate, bachelor, master, and doctoral degrees through three university campuses, seven community college campuses, an employment...
, SAIC
Science Applications International Corporation
SAIC is a FORTUNE 500 scientific, engineering and technology applications company headquartered in the United States with numerous federal, state, and private sector clients...
, Ball Aerospace
Ball Aerospace
Ball Aerospace & Technologies Corp. is a manufacturer of spacecraft, components, and instruments for national defense, civil space and commercial space applications. The company is a wholly owned subsidiary of Ball Corp...
, and Max-Planck-Institut für extraterrestrische Physik.
Spacecraft design and instrumentation
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
consists of two main sections, the 370-kg (815-lb) copper-core "Smart Impactor" that impacted the comet, and the "Flyby" section, which imaged the comet from a safe distance during the encounter with Tempel 1.
The Flyby spacecraft is about 3.2 meters (10.5 ft) long, 1.7 meters (5.6 ft) wide and 2.3 meters (7.5 ft) high. It includes two solar panels, a debris shield, and several science instruments for imaging
Speckle imaging
Speckle imaging describes a range of high-resolution astronomical imaging techniques based either on the shift-and-add method or on speckle interferometry methods...
, infrared spectroscopy
Infrared spectroscopy
Infrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...
, and optical navigation to its destination near the comet. The spacecraft also carried two cameras, the High Resolution Imager (HRI), and the Medium Resolution Imager (MRI). The HRI is an imaging device that combines a visible-light camera with a filter wheel, and an imaging infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
called the "Spectral Imaging Module" or SIM that operates on a spectral band from 1.05 to 4.8 micrometres. It has been optimized for observing the comet's nucleus. The MRI is the backup device, and was used primarily for navigation during the final 10-day approach. It also has a filter wheel, with a slightly different set of filters.
The Impactor section of the spacecraft contains an instrument that is optically identical to the MRI, called the Impactor Targeting Sensor (ITS), but without the filter wheel. 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. As the Impactor neared the comet's surface, this camera took high-resolution pictures of the nucleus (as good as 0.2 metres (7.9 in) per pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
) that were transmitted in real-time to the Flyby spacecraft before it and the Impactor were destroyed. The final image taken by the impactor was snapped only 3.7 seconds before impact.
The impactor's payload, dubbed the "Cratering Mass", was 100% copper (impactor 49% copper by mass) to reduce debris interfering with scientific measurements of the impact. Since copper was not expected to be found on a comet, scientists could eliminate copper from the spectrometer reading. Instead of using explosives, it was also cheaper to use copper as the payload.
The name of the mission is shared with the 1998 Deep Impact
Deep Impact (film)
Deep Impact is a 1998 science-fiction disaster-drama film released by Paramount Pictures and DreamWorks in the United States on May 8, 1998. The film was directed by Mimi Leder and stars Robert Duvall, Elijah Wood, Téa Leoni, and Morgan Freeman...
film, in which a comet strikes the Earth. This is coincidental, however, as the scientists behind the mission and the creators of the film devised the name independently of each other at around the same time.
Mission profile
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
s of kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
—the equivalent of 4.7 ton
Ton
The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...
s of TNT. Scientists believed that the energy of the high-velocity collision would be sufficient to excavate a crater up to 100 m (328 ft) wide (larger than the bowl of the Roman Colosseum
Colosseum
The Colosseum, or the Coliseum, originally the Flavian Amphitheatre , is an elliptical amphitheatre in the centre of the city of Rome, Italy, the largest ever built in the Roman Empire...
). The size of the crater was still not known one year after the impact.
Just minutes after the impact, the flyby probe passed by the nucleus at a close distance of 500 km (310.7 mi), taking pictures of the crater position, the ejecta plume, and the entire cometary nucleus. The entire event was photographed by Earth-based telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s and orbital observatories
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
, including the Hubble
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
, Chandra
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...
, Spitzer
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
, and XMM-Newton
XMM-Newton
The XMM-Newton is an orbiting X-ray observatory launched by ESA in December 1999 on a Ariane 5 rocket...
. 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
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...
cloud that was kicked up by the impact.
Before launch
Discovery Program
NASA's Discovery Program is a series of lower-cost, highly-focused American scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA Administrator Daniel S. Goldin's vision of "faster, better, cheaper" planetary missions...
of low-cost spacecraft. The two spacecraft (Impactor and Flyby) and the three main instruments were built and integrated by Ball Aerospace & Technologies Corp. in Boulder, Colorado
Boulder, Colorado
Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of...
. Developing the software for the spacecraft took 18 months and the application code consisted of 20,000 lines and 19 different application threads. The total cost of developing the spacecraft and completing its mission reached US$330 million.
Launch and commissioning phase
The probe was originally scheduled for launch on December 30, 2004, but NASA officials delayed its launch, in order to allow more time for testing the software. It was successfully launched from Cape CanaveralCape Canaveral
Cape Canaveral, from the Spanish Cabo Cañaveral, is a headland in Brevard County, Florida, United States, near the center of the state's Atlantic coast. Known as Cape Kennedy from 1963 to 1973, it lies east of Merritt Island, separated from it by the Banana River.It is part of a region known as the...
on January 12, 2005 at 1:47 pm EST (1847 UTC) by a Delta 2 rocket.
Deep Impacts state of health was uncertain during the first day after launch. Shortly after entering orbit around the Sun and deploying its solar panels, the probe switched itself to safe mode
Safe mode (spacecraft)
Safe mode is an operating mode of a modern spacecraft during which all non-essential systems are shut down and only essential functions such as thermal management, radio reception and attitude control are active.-Triggering events:...
. The cause of the problem was simply an incorrect temperature limit in the fault protection logic for the spacecraft's RCS thruster catalyst beds. The spacecraft's thrusters were used to detumble the spacecraft following third stage separation. NASA subsequently announced that the probe was out of safe mode and healthy.
On February 11, Deep Impacts rockets were fired as planned to correct the spacecraft's course. This correction was so precise that the next planned maneuver for March 31 was canceled. The "commissioning phase" verified that all instruments were activated and checked out. During these tests it was found that the HRI images were not in focus after it underwent a bake-out period. After mission members investigated the problem, on June 9, it was announced that by using image processing software and the mathematical technique of deconvolution, the HRI images could be corrected to restore much of the resolution anticipated.
Cruise phase
On May 4 the spacecraft executed its second trajectory correction maneuver. Burning its rocket engine for 95 seconds, the spacecraft speed was changed by 18.2 km/h (11.3 mph). Rick Grammier, the project manager for the mission at NASA's Jet Propulsion Laboratory, reacted to the maneuver stating that "spacecraft performance has been excellent, and this burn was no different...it was a textbook maneuver that placed us right on the money."
Approach phase
The approach phase extended from 60 days before encounter (May 5) until five days beforeencounter. Sixty days out was the earliest time that the Deep Impact spacecraft was expected to detect the comet with its MRI camera. In fact, the comet was spotted ahead of schedule, 69 days before impact (see Cruise phase above). This milestone marks the beginning of an intensive period of observations to refine knowledge of the comet's orbit and study the comet's rotation, activity, and dust environment.
On June 14 and June 22, Deep Impact observed two outbursts of activity from the comet, the latter being six times larger than the former. The spacecraft studied the images of various distant stars to determine its current trajectory and position. 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. You have to rely on the fact that the Impactor is a smart spacecraft as is the Flyby spacecraft. So you have to build in the intelligence ahead of time and let it do its thing." On June 23, the first of the two final trajectory correct maneuvers (targeting maneuver) was successfully executed. A 6 m/s (13.4 mph) velocity change was needed to adjust the flight path towards the comet and target the impactor at a window in space about 100 kilometres (62.1 mi) wide.
Impact phase
The flyby spacecraft performed one of two divert maneuvers to avoid damage. A 14-minute burn was executed which slowed down the spacecraft. It was also reported that the communication link between the flyby and the impactor was functioning as expected. The impactor spacecraft executed three correction maneuvers in the final two hours before impact.
The impactor was maneuvered to plant itself in front of the comet, so that 9P/Tempel would collide with it. Impact occurred at 05:45 UTC (05:52 Ground UTC, +/- up to three minutes, one-way light time = 7m 26s) on the morning of July 4, within one second of the expected time for impact.
The impactor returned images as late as three seconds before impact. 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. The energy from the collision was similar in size to exploding five tons of dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
and the comet shone six times brighter than normal.
Impact Phase Timeline (NASA)
Results
North American Eastern Time Zone
The Eastern Time Zone of the United States and Canada is a time zone that falls mostly along the east coast of North America. Its UTC time offset is −5 hrs during standard time and −4 hrs during daylight saving time...
. Once news of a successful impact had taken place, the mission control team members applauded and hugged each other. Don Yeomans confirmed the results for the press, "We hit it just exactly where we wanted to" and JPL Director Charles Elachi stated "The success exceeded our expectations."
In the post-impact briefing at 0100 Pacific Daylight Time (08:00 UTC) on July 4, 2005, the first processed images revealed existing craters
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
on the comet. NASA scientists stated they could not see the new crater that had formed from the impactor, but it was later discovered to be about 100 meters (328 ft) wide and up to 30 meters (98 ft) deep. Lucy McFadden, one of the co-investigators of the impact, stated "We didn't expect the success of one part of the mission [bright dust cloud] to affect a second part [seeing the resultant crater]. But that is part of the fun of science, to meet with the unexpected." Analysis of data from the Swift X-ray telescope
Swift Gamma-Ray Burst Mission
The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 20 November 2004, 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international...
showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of 5 million kilograms (11 million pounds) of water and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact.
Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous models which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to talcum powder rather than sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
. Other materials found while studying the impact included clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
s, carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
s, sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
, and crystalline silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
s which were found by studying the spectroscopy of the impact. Clays and carbonates usually require liquid water to form and sodium is rare in space. Observations also revealed that the comet was about 75% empty space, and one astronomer compared the outer layers of the comet to the same makeup of a snow bank. Astronomers have expressed interest in more missions to different comets to determine if they share similar compositions or if there are different materials found deeper within comets that were produced at the time of the solar system's formation.
Astronomers hypothesized, based on its interior chemistry, that the comet formed in the Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
and Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
Oort cloud
Oort cloud
The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
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
Ethane
Ethane is a chemical compound with chemical formula C2H6. It is the only two-carbon alkane that is an aliphatic hydrocarbon. At standard temperature and pressure, ethane is a colorless, odorless gas....
, which was present in 9P/Tempel. Astronomers believe that other comets with compositions similar to Tempel 1 are likely to have formed in the same region.
Crater
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. The mission utilized the already existing Stardust spacecraftStardust (spacecraft)
Stardust is a 300-kilogram robotic space probe launched by NASA on February 7, 1999 to study the asteroid 5535 Annefrank and collect samples from the coma of comet Wild 2. The primary mission was completed January 15, 2006, when the sample return capsule returned to Earth...
, which had studied Comet Wild 2 in 2004. Stardust was placed into a new orbit so that it approached Tempel 1 at a distance of approximately 200 km (124.3 mi) on February 15, 2011, 04:42 UTC. This was the first time that a comet was visited twice, and provided an opportunity to better observe the crater that was created by Deep Impact as well as observing the changes caused by the comet’s latest close approach to the Sun.
On February 15, NASA scientists identified the crater formed by Deep Impact in images from Stardust. The crater is estimated to be 150 meters (500 ft) in diameter, and has a bright mound in the center likely created when material from the impact fell back into the crater.http://www.nasa.gov/mission_pages/stardust/multimedia/Schultz4.html
Media coverage
Waikiki
Waikiki is a neighborhood of Honolulu, in the City and County of Honolulu, on the south shore of the island of Oahu, in Hawaii. Waikiki Beach is the shoreline fronting Waikīkī....
.
Experts came up with a range of soundbites to summarize the mission to the public. Iwan Williams of Queen Mary, University of London
Queen Mary, University of London
Queen Mary, University of London is a public research university located in London, United Kingdom and a constituent college of the federal University of London...
, said "It was like a mosquito hitting a 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
. What we've found is that the mosquito didn't splat on the surface; it's actually gone through the windscreen."
One day after the impact Marina Bay, a Russian astrologer
Astrologer
An astrologer practices one or more forms of astrology. Typically an astrologer draws a horoscope for the time of an event, such as a person's birth, and interprets celestial points and their placements at the time of the event to better understand someone, determine the auspiciousness of an...
, sued NASA for $300 million for the impact which "ruin[ed] the natural balance of forces in the universe." 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. If your phone went down this morning, ask yourself Why? and then get in touch with us." On August 9, 2005 the Presnensky Court of Moscow ruled against Bay, although she did attempt to appeal the result. One Russian physicist said that the impact had no effect on Earth and "the change to the orbit of the comet after the collision was only about 10 cm (3.9 in)."
Send Your Name To A Comet!
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
's website were invited to submit their name between May 2003 and January 2004, and the names gathered—some 625,000 in all—were then burnt onto a mini-CD, which was attached to the impactor. Dr. Don Yeomans, a member of the spacecraft's scientific team, stated "this is an opportunity to become part of an extraordinary space mission ... when the craft is launched in December 2004, yours and the names of your loved-ones can hitch along for the ride and be part of what may be the best space fireworks show in history." The idea was credited with driving interest in the mission.
Reaction from China
Chinese researchers used the Deep Impact mission as an opportunity to highlight the efficiency of American science because public support ensured the possibility of funding long-term research. 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."Two days after the U.S. mission succeeded in having a probe collide with a comet, China revealed a plan for what it called a "more clever" version of the mission: landing a probe on a small comet or asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
to push it off course. China will begin the mission after sending a probe to the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
.
Contributions from amateur astronomers
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
images of the comet.
One notable amateur observation was by students from schools in Hawaii, working with US and UK scientists, who during the press conference took live images using the Faulkes Automatic Telescope
Faulkes Telescope North
The Faulkes Telescope North is a clone of the Liverpool Telescope, and is located at Haleakala Observatory in the U.S. state of Hawaii.The telescope is owned and operated by LCOGT. This telescope and its sister telescope Faulkes Telescope South are used by research and education groups across the...
in Hawaii (the students operated the telescope over the Internet) and were one of the first groups to get images of the impact. One amateur astronomer reported seeing a structureless bright cloud around the comet, and an estimated magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
2 increase in brightness after the impact. Another amateur published a map of the crash area from NASA images.
Musical tribute
The Deep Impact mission coincided with celebrations in the Los Angeles area marking the 50th anniversary of "Rock Around the ClockRock Around the Clock
"Rock Around the Clock" is a 12-bar-blues-based song written by Max C. Freedman and James E. Myers in 1952. The best-known and most successful rendition was recorded by Bill Haley and His Comets in 1954...
" by Bill Haley and His Comets becoming the first rock and roll
Rock and roll
Rock and roll is a genre of popular music that originated and evolved in the United States during the late 1940s and early 1950s, primarily from a combination of African American blues, country, jazz, and gospel music...
single to reach No. 1 on the recording sales charts. Within twenty-four hours of the mission's success, a two-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 and His Comets performing in 1955 and the surviving original members of The Comets performing in March 2005. The video was posted to NASA's website for a couple of weeks afterwards.
On July 5, the surviving original members of The Comets (ranging in age from 71 to 84) performed a free concert for hundreds of employees of the Jet Propulsion Laboratory to help them celebrate the mission's success. This event received worldwide press attention. Later, in February 2006, the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
citation that officially named asteroid 79896 Billhaley
79896 Billhaley
79896 Billhaley is a Main Belt asteroid previously designated which in February 2006 was renamed in honor of rock and roll pioneer Bill Haley. The new designation commemorated the 25th anniversary of the death of the acclaimed musician in February 1981...
included a reference to the JPL concert.
Extended mission
Deep Impact is now on an extended mission designated EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) to visit other comets, after being put to sleep in 2005 upon completion of the Tempel 1 mission.Comet Boethin plan
Its first extended visit was to do a flyby of Comet Boethin, but with some complications. 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.The original plan was for a December 5, 2008 flyby of Comet Boethin
85P/Boethin
Comet Boethin is a periodic comet discovered in 1975 by Reverend Leo Boethin. It appeared again in 1986 January as expected...
, coming within 700 kilometres (435 mi) of the comet. Michael A'Hearn, the Deep Impact team leader, explained "We propose to direct the spacecraft for a flyby of Comet Boethin to investigate whether the results found at Comet Tempel 1 are unique or are also found on other comets." The $40 million mission would provide about half of the information as the collision of Tempel 1 but at a fraction of the cost. Deep Impact would use its spectrometer to study the comet's surface composition and its telescope for viewing the surface features.
However, as the Earth gravity assist approached, astronomers were unable to locate Comet Boethin, which may have broken up into pieces too faint to be observed. Consequently, its orbit could not be calculated with sufficient precision to permit a flyby.
Flyby of Comet Hartley 2
JPL team targeted Deep Impact toward Comet 103P/Hartley103P/Hartley
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia...
(Hartley 2). However, this would require an extra two years of travel for Deep Impact. On May 28, 2010, a burn of 11.3 seconds was conducted, to enable the June 27 Earth fly-by to be optimized for the transit to Hartley 2 and fly-by on November 4. The velocity change was 0.1 metre per second (0.22369362920544 mph).
On November 4, 2010, the Deep Impact extended mission (EPOXI) returned images from comet Hartley 2. EPOXI came within 700 kilometres (435 mi) of the comet, returning detailed photographs of the "peanut" shaped cometary nucleus and several bright jets. The probe's medium-resolution instrument captured the photographs.
See also
- Lunar Crater Observation and Sensing SatelliteLCROSSThe Lunar Crater Observation and Sensing Satellite was a robotic spacecraft operated by NASA. The mission was conceived as a low-cost means of determining the nature of hydrogen detected at the polar regions of the moon. The main LCROSS mission objective was to explore the presence of water ice...
(LCROSS) – Satellite that impacted Earth's moon in 2009 in an attempt to eject water
External links
Official websites- Deep Impact at JPL
- Deep Impact at NASA
- EPOXI (Extended Mission at NASA)
- Deep Impact Mission Profile by NASA's Solar System Exploration
- Deep Impact at the University of Maryland, College Park
- Deep Impact at Ball Aerospace & Technologies Corp.
- Deep Impact encounter press kit
- Deep Impact: Mission Science Q&A", NASA
Additional information
- Space.com Technology page on Deep Impact
- Watch a mini-doco about Deep Impact from Australian TV, August 4, 2005
- Deep Impact Reveals Comet's Components – Scientific American
- Deep Impact: Our First Look Inside a Comet. June 2005 issue of Sky and Telescope magazine, pp. 40–44
Maps, photos, and other images
Other languages
- Croatian: Deep Impact images and information
- French: Photos and videos of the impact