Deep impact

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The medium-resolution camera on Deep Impact's flyby spacecraft took this image on Monday, July 4, 2005, Eastern Daylight Time, during the mission's encounter with comet Tempel 1.

"The challenges of this mission and teamwork that went into making it a success, should make all of us very proud." - Rick Grammier, Deep Impact project manager, NASA's Jet Propulsion Laboratory

"This mission is truly a smashing success. Tomorrow and in the days ahead we will know a lot more about the origins of our solar system" - Andy Dantzler, director of NASA's Solar System Division.

"The image clearly shows a spectacular impact. With this much data we have a long night ahead of us, but that is what we were hoping for. There is so much here it is difficult to know where to begin." - Dr. Michael A'Hearn, University of Maryland, Deep Impact principal investigator.

"The impactor kicked into its autonomous navigation mode right on
Time. Our preliminary analysis indicates the three impactor targeting manoeuvres occurred on time at 90, 35 and 12.5 minutes before impact." - Shyam Bhaskaran, Deep Impact navigator.

Complete Mission Coverage

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Quicktime movie of impact (700Kb)

Quicktime movie of impact

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After 172 days and 268 million miles of deep space stalking, Deep Impact successfully reached out and touched comet Tempel 1.
The collision between the coffee table-sized impactor and city-sized comet occurred at 05:52 GMT.

Official word of the impact came 5 minutes after impact when, at 05:57 GMT, an image from the spacecraft's medium resolution camera was downlinked to the computer screens of the mission's science team showed the tell-tale signs of a high-speed impact.

The celestial collision and ensuing data collection by the nearby Deep Impact mothership was the climax of a very active 24 hour period for the mission which began with impactor release at 06:07 GMT on July 3 2005.
Deep space manoeuvres by the flyby, final checkout of both spacecraft and comet imaging took up most of the next 22 hours. Then, the impactor got down to its last two hours of life.

At the moment the impactor was vaporizing itself in its 6.3 miles a second collision with comet Tempel 1, the Deep Impact flyby spacecraft was monitoring events from nearby and will continue to do so for the next several days.

Deep Impact will provide a glimpse beneath the surface of a comet, where material from the solar system's formation remains relatively unchanged.
Mission scientists expect the project will answer basic questions about the formation of the solar system, by offering a better look at the nature and composition of the frozen celestial travelers known as comets.

Deep Impact image

"The flyby surviving closest approach and shield mode has put the cap on an outstanding day. Soon, we will begin the process of down linking all the encounter information in one batch and hand it to the science team" - Rick Grammier.


	Tempel 1

Comet Tempel 1 produced a blast that has scientists puzzling over at NASA's Jet Propulsion Laboratory in California.
"Geez, and we thought it was going to be subtle. That was considerably brighter, and had considerably more material coming out, than I had expected" -Don Yeomans, JPL scientist of the Deep Impact science team.
The aim of the cosmic collision was to punch a hole in the comet's crusty surface and reveal details about the primordial material in the interior of the comet.
One reason for the spectacular burst could be that puncturing the comet's crust released subsurface pressure, allowing a much bigger plume of ejecta to spurt out.
A few amateur astronomers noted a that the comet has brightened by 2 magnitudes.

NASA's Hubble Space Telescope captured the dramatic effects of the collision.

This sequence of images shows the comet before and after the impact.
The image at left shows the comet about a minute before the impact. The encounter occurred at 05:52 GMT.
In the middle image, captured 15 minutes after the collision, Tempel 1 appears four times brighter than in the pre-impact photo. Astronomers noticed that the inner cloud of dust and gas surrounding the comet's nucleus increased by about 200 kilometres in size. The impact caused a brilliant flash of light and a constant increase in the brightness of the inner cloud of dust and gas.
The Hubble telescope continued to monitor the comet, snapping another image (at right) 62 minutes after the encounter. The gas and dust ejected during the impact are expanding outward in the shape of a fan. The fan-shaped debris is traveling at about 1,800 kilometres an hour, or twice as fast as the speed of a commercial jet. The debris extends about 1,800 kilometres from the nucleus.


	Actual impact

A simulation of the impact did not display the same debris cloud. The actual fan shaped cloud was more hemisphericaly spread and it is thought that the crater is large and shallow. The Impact was estimated to have released 19 Gigajoules of energy, or the equivalent of 4.5 tons of TNT.

"How a washing-machine sized impactor could produce such a large disturbance is going to take some explanation" -Don Yeomans.

Image credit: NASA/JPL-Caltech/UMD

These two images were taken by NHK's HDTV camera and the Cooled Mid-Infrared Camera and Spectrograph (COMICS) on the Subaru telescope.

Pre-impact:
Friday, July 1, 8:13 p.m. HST (false colour)

Post-impact:
Sunday, July 3, 9:50 p.m. HST (false colour)

XMM-Newton images

These images, taken by the Optical Monitor on board ESA's XMM-Newton observatory on 3 and 4 July 2005, show a comparison between the states of the comet before and just after impact.
The images were taken in the blue (top) and ultraviolet channels (bottom) of the instrument. The ultraviolet images show the emissions of hydroxyl ions, the direct decay product of water.
About 1.5 hours after the impact, the brightness of hydroxyl groups is increased by a factor of about five. Later, about 4.5 hours after the impact the ultraviolet emission is decreased again which indicates that the peak has passed.
The presence of water in Tempel 1 is consistent with preliminary measurements of the composition of the comet made last week by the ALICE instrument on ESA's Rosetta spacecraft.

This image of Comet 9P/Tempel 1 was obtained on 4 July 2005 by one of the European Photon Imaging Cameras (EPIC) on board XMM-Newton.

XMM-Newton observed that Tempel 1 emits X-rays, as suspected from previous observations of comets, but this emission is very weak. It is not certain whether it is possible to obtain spectral data which indicate the mechanisms by which the comet's X-rays are produced.
Further analysis of the XMM-Newton data is needed to confirm this.

With silicon chips that can register extremely weak X-ray radiation, these advanced Charge-Coupled Device cameras (CCD) are capable of detecting rapid variations in intensity, down to a thousandth of a second and less.!

Credits: ESA

The 2m robotic Faulkes telescope in Hawaii transmitted its images to centres across the UK.

Scientists could not immediately determine the size of the crater produced by the impact because of the large plume of ice, dust and gases streaming out and obscuring one end of the comet, which is half the size of Manhattan.

These animations, composed of images taken by the OSIRIS Narrow Angle Camera on board ESA's Rosetta spacecraft, shows how the brightness of Comet 9P/Tempel 1 developed after impact.
The separate false-colour images in this sequence from OSIRIS were taken at five-minute intervals around the impact time of 07:52 CEST (05:52 GMT/UT).
Although in the false-colour images (a still seen here at right) the increase in visual brightness is not so obvious, it becomes very clear in the animated surface plot below.

Credits: ESA/OSIRIS consortium

Observatorio del Teide images

Dust and gas are seen in these images of Comet 9P/Tempel 1, as observed with the 1-metre ESA Optical Ground Station (OGS) telescope, located at the Observatorio del Teide on Tenerife, Canary Islands.

Two different filters have been used in different visible light observations to study different aspects of the comet's nature. Red 'broadband' filters allowed the detection of dust, while blue 'narrowband' filters, filtering only carbon gaseous compounds, allow the observations to concentrate mainly on the gas emissions of the comet.

The first set of images here were taken with a broadband red filter, four days before and about 15 hours after the impact respectively. The images were exposed for 10 minutes and show the dust coma of the comet. The dust brightness has increased by 50 percent.

Observatorio del Teide images

A strong jet has recently appeared as a direct result of the impact, pointing north-north-east. The overall coma is very asymmetric in appearance. All structures must have been created by the outburst triggered by the impact.

The second set of images of Tempel 1 from the OGS telescope use a narrowband filter (C2 emission band).

They show the coma gas mixed with smaller-sized dust particles than observed in the broadband red filtered image.

The observations were taken two days before and about 16 hours after the impact respectively. Also here the coma brightness has increased by 50 percent. Again the same strong jet is visible.

Observatorio del Teide images

In the third set of images, Tempel 1 is seen about 16 hours after the impact. The two images show the refection of blue (BC filter) and red (RC filter) light from the dust cloud surrounding the comet nucleus.
These reflections show different dust particle sizes, with blue particles being smaller than red particles.
It is clear that the jet structure of the smaller dust particles points towards the north (BC image), whereas the jet composed of larger dust particles (RC image) is rotated by about 45 degrees towards the north-east.
This means that the direction in which the dust particles were ejected from the comet nucleus after impact seems to depend on the particle size.

Date(TT)  R.A. (2000) Decl.   Delta     r    Elong.  m1   
July 04  13 37.41  -09 27.9   0.893   1.506   104    9.7  
July 09  13 46.80  -11 25.6   0.920   1.507   102    9.8  
July 14  13 56.90  -13 21.4   0.948   1.509   100    9.8  
July 19  14 07.66  -15 14.6   0.979   1.512    99    9.9  
July 24  14 19.03  -17 04.4   1.011   1.518    97   10.1  
July 29  14 30.98  -18 50.0   1.045   1.525    95   10.2

OSCULATING ORBITAL ELEMENTS
(heliocentric ecliptic J2000)
Epoch = 2005-03-11 (2453440.5) TDB

e = 0.517568076214557	i = 10.5296283368193 deg
q = 1.50612674035782 AU	w = 178.837968857731 deg
a = 3.1219466749627 AU	node = 68.941170658754 deg
Q = 4.73776661 AU	M = 339.217101151724 deg
P = 5.5163 y	n = 0.178676 deg/d
TP = 2005-07-05.3162176 (2453556.81621756) TDB

The impact occurred at 07:52 CEST but because the comet has already set in Chile at that time, observers at the La Silla Paranal Observatory could only start observing several hours later.
The first observations were done in the infrared by TMMI2 at the 3.6m telescope at La Silla, at 21:20 CEST (still daylight in Chile).

TIMMI2 images of Comet Tempel 1, before (left) and after (right) impact.

FORS2 images of Comet Tempel 1, before (top) and after (bottom) impact.

At sunset in Chile, all 7 telescopes of the La Silla Paranal Observatory went into operations.
The FORS2 multi-mode instrument on Antu, one of the 8.2m Unit Telescope of the VLT array, took stunning images, showing that the morphology of the comet had dramatically changed: a new bright fan-like structure was now visible.

Other telescopes have provided observations of the comet as well.
NACO took some images of the central part of the coma, while UVES performed high-dispersion spectroscopy of the comet, in order to compare with the previous nights. First estimates indicate the emission lines to be more pronounced by 10 to 20 %.

At La Silla, the SOFI instrument at the NTT telescope, imaged the comet in the near-infrared. An image in the J-band also shows the dust shell from the impact in the south-western quadrant of the coma.
The very inner coma (indicated by the white box) shows on-going enhanced activity compared to the pre-impact level.

SOFI image in the J-band of Comet Tempel 1 after the impact.

Scientists using the Swift satellite also witnessed the impact.

Swift provided the only simultaneous multi-wavelength observation of this rare event, with a suite of instruments capable of detecting optical light, ultraviolet, X-rays and gamma rays.
Different wavelengths reveal different secrets about the comet.
So far, after a set of eight observations each lasting about 50 minutes, Swift scientists have seen a quick and dramatic rise in ultraviolet light, evidence that the Deep Impact probe struck a hard surface, as opposed to a softer, snowy surface.
More observations and analysis are expected in the coming days from teams at NASA and Penn State and in Italy and the United Kingdom.

29 June (before impact): Movie showing the comet Tempel 1 tracking across the sky on 29 June 2005 using the Swift Ultraviolet/Optical Telescope (UVOT) through an ultraviolet filter centred on 2600 Angstroms. This sequence covers 40 minutes of elapsed time.

This graph shows the two spectra acquired by the Spitzer Space Telescope before (middle) and after (bottom) it observed NASA's Deep Impact smash into comet Tempel 1. Above them is a past spectrum of comet Hale-Bopp, which illustrates the extra detail seen by Spitzer in Tempel 1.

It found standard comet components, such as silicate, though smaller than typical sand grains. But it also found clay and carbonates. These were unexpected because they are thought to require liquid water to form.

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