Category: Comets

View of the material ejected from Tempel 1. Image credit: NASA/JPL.
After 172 days and 431 million kilometers (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 1:52 a.m. EDT.

“What a way to kick off America’s Independence Day,” said Deep Impact Project Manager Rick Grammier of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “The challenges of this mission and teamwork that went into making it a success, should make all of us very proud.”

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

Official word of the impact came 5 minutes after impact. At 1:57 a.m. EDT, an image from the spacecraft’s medium resolution camera downlinked to the computer screens of the mission’s science team showed the tell-tale signs of a high-speed impact.

“The image clearly shows a spectacular impact,” said Deep Impact principal investigator Dr. Michael A’Hearn of the University of Maryland, College Park. “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.”

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 2:07 a.m. EDT on July 3. Deep space maneuvers 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.

“The impactor kicked into its autonomous navigation mode right on time,” said Deep Impact navigator Shyam Bhaskaran, of JPL. “Our preliminary analysis indicates the three impactor targeting maneuvers occurred on time at 90, 35 and 12.5 minutes before impact.”

At the moment the impactor was vaporizing itself in its 10 kilometers per second (6.3 miles per second) collision with comet Tempel 1, the Deep Impact flyby spacecraft was monitoring events from nearby. For the following14 minutes the flyby collected and downlinked data as the comet loomed ever closer. Then, as expected at 2:05 a.m. EDT, the flyby stopped collecting data and entered a defensive posture called shield mode where its dust shields protect the spacecraft’s vital components during its closest passage through the comet’s inner coma. Shield mode ended at 2:32 a.m. EDT when mission control re-established the link with the flyby spacecraft.

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

The goal of the Deep Impact mission is to 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.

The University of Maryland is responsible for overall Deep Impact mission science, and project management is handled by JPL. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo.

For information about Deep Impact on the Internet, visit http://www.nasa.gov/deepimpact.

Original Source: NASA/JPL News Release

Deep Impact took this image of its own impactor drifting away from the spacecraft. Image credit: NASA/JPL. Click to enlarge.
One hundred and seventy-one days into its 172-day journey to comet Tempel 1, NASA’s Deep Impact spacecraft successfully released its impactor at 11:07 p.m. Saturday, Pacific Daylight Time (2:07 a.m. Sunday, Eastern Daylight Time).

At release, the impactor was about 880,000 kilometers (547,000 miles) away from its quarry. The separation of flyby spacecraft and the washing-machine-sized, copper-fortified impactor is one in a series of important mission milestones that will cap off with a planned encounter with the comet at 10:52 p.m. Sunday, PDT (1:52 a.m. on July 4, EDT).

Six hours prior to impactor release, the Deep Impact spacecraft successfully performed its fourth trajectory correction maneuver. The 30-second burn changed the spacecraft’s velocity by about one kilometer per hour (less than one mile per hour). The goal of the burn is to place the impactor as close as possible to the direct path of onrushing comet Tempel 1.

Soon after the trajectory maneuver was completed, the impactor engineers began the final steps that would lead to it being ready for free flight. The plan culminated with activation of the impactor’s batteries at 10:12 p.m., PDT (1:12 a.m. Sunday, EDT). Deep Impact’s impactor has no solar cells; the vehicle’s batteries are expected to provide all the power required for its short day-long life.

In order to release the impactor, separation pyros fired allowing a spring to uncoil and separate the two spacecraft at a speed of about 35 centimeters per second (0.78 mile per hour).

With Tempel 1 closing the distance between it and impactor at about 10 kilometers (6 miles) per second, there is little time for mission controllers to admire their work. Twelve minutes after impactor release the flyby began a 14-minute long divert burn that slowed its velocity relative to the impactor by 102 meters per second (227 miles per hour), moving it out of the path of the onrushing comet nucleus and setting the stage for a ringside seat of celestial fireworks to come less than 24 hours later.

Deep Impact mission controllers have confirmed the impactor’s S-band antenna is talking to the flyby spacecraft. All impactor data including the expected remarkable images of its final dive into the comet’s nucleus will be transmitted to the flyby craft — which will then downlink them to Deep Space Network antennas that are listening 134 million kilometers (83 million miles) away.

While all is going as expected on the Deep Impact spacecraft the comet itself is putting on something of a show. The 14-kilometer-long (8.7-mile-long) comet Tempel 1 displayed another cometary outburst on July 2 at 1:34 a.m. PDT (4:34 a.m.EDT) when a massive, short-lived blast of ice or other particles escaped from inside the comet’s nucleus and temporarily expanded the size and reflectivity of the cloud of dust and gas (coma) that surrounds it. The July 2 outburst is the fourth observed in the past three weeks.

Three of the outbursts appear to have originated from the same area on the surface of the nucleus but they do not occur every time that that area faces the Sun.

“The comet is definitely full of surprises so far and probably has a few more in store for us,” said Deep Impact Project Manager Rick Grammier of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “None of this overly concerns us nor has it forced us to modify our nominal mission plan.”

Information and images from a camera aboard Deep Impact’s impactor and flyby spacecraft can be watched in near-real time at http://www.nasa.gov/deepimpact.

For additional information about Deep Impact on the Internet, visit NASA Deep Impact.

Original Source: NASA News Release

Rosetta’s photograph of Comet Tempel 1, it’s down on the lower left. Image credit: ESA. Click to enlarge.
ESA?s Rosetta comet-chaser spacecraft has acquired its first view of the Deep Impact target, Comet 9P/Tempel 1.

This first Rosetta image of the Deep Impact campaign was taken by its Navigation Camera (NAVCAM) between 08:45 and 09:15 CEST on 28 June 2005.

The image shows that the spacecraft now points towards Comet 9P/Tempel 1 in the correct orientation. The NAVCAM is pointing purposely slightly off-target to give the best view to the science instrumentation.

The NAVCAM system on board Rosetta was activated for the first time on 25 July 2004. This system, comprising two separate independent camera units (for back-up), will help to navigate the spacecraft near the nucleus of Comet 67P/Churyumov-Gerasimenko in ten years time.

In the meantime though, the cameras can also be used to track other objects, such as Comet Tempel 1, and the two asteroids that Rosetta will be visiting during its long cruise, Steins and Lutetia.

The cameras perform both as star sensors and imaging cameras (but not with the same high resolution as some of its other instruments), and switch functions by means of a refocusing system in front of the first lens.

The magnitude of Comet Tempel 1 is at the detection limit of the camera: it is not as easily visible in the raw image and the image here is a composite of 20 exposures of 30 seconds each.

The comet is the fuzzy object with the tail in the lower left of the image. The faintest stars visible in this image are about 13th magnitude, the bright star in the upper left is about 8th magnitude. The image covers about 0.5 degrees square, and celestial north is to the right.

Original Source: ESA News Release

Artist illustration of Deep Impact with Comet Tempel 1. Image credit: NASA/JPL. Click to enlarge.
NASA’s Deep Impact spacecraft observed a massive, short-lived outburst of ice or other particles from comet Tempel 1 that temporarily expanded the size and reflectivity of the cloud of dust and gas (coma) that surrounds the comet nucleus.

The outburst was detected as a dramatic brightening of the comet on June 22. It is the second of two such events observed in the past two weeks. A smaller outburst also was seen on June 14 by Deep Impact, the Hubble Space Telescope and by ground based observers.

“This most recent outburst was six times larger than the one observed on June 14, but the ejected material dissipated almost entirely within about a half day,” said University of Maryland College Park astronomer Michael A’Hearn, principal investigator for the Deep Impact mission. A’Hearn noted that data from the spectrometer aboard the spacecraft showed that during the June 22 outburst the amount of water vapor in the coma doubled, while the amount of other gases, including carbon dioxide, increased even more.

A movie of the cometary outburst is available on the Internet at http://www.nasa.gov/deepimpact .

“Outbursts such as this may be a very common phenomenon on many comets, but they are rarely observed in sufficient detail to understand them because it is normally so difficult to obtain enough time on telescopes to discover such phenomena,” A’Hearn said. “We likely would have missed this exciting event, except that we are now getting almost continuous coverage of the comet with the spacecraft’s imaging and spectroscopy instruments.”

Deep Impact co-investigator Jessica Sunshine, with Science Applications International Corporation, Chantilly, Va., agreed that observing such activity twice in two weeks suggests outbursts are fairly common. “We must now consider them as a significant part of the processing that occur on comets as they heat up when approaching the sun,” she said.

Comet Tempel 1 is near perihelion, or the point in its orbit at which it is closest to the Sun.

“This adds to the level of excitement as we come down to the final days before encounter,” said Rick Grammier, Deep Impact project manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “But this comet outburst will require no modification to mission plan and in no way affects spacecraft safety.”

Deep Impact consists of a sub-compact-car-sized flyby spacecraft and an impactor spacecraft about the size of a washing machine. The dual spacecraft carries three imaging instruments, two on the flyby spacecraft and one on the impactor. A spectrometer on the flyby spacecraft uses the same telescope as the flyby’s high- resolution imager.

The final prelude to impact will begin early on July 3, 24 hours before the 1:52 a.m. EDT July 4th impact, when the flyby spacecraft releases the impactor into the path of the comet. Like a copper penny pitched up into the air just in front of a speeding tractor-trailer truck, the 820-pound impactor will be run down by the comet, colliding with the nucleus at a closing speed of 23,000 miles per hour. Scientists expect the impact to create a crater several hundred feet in size; ejecting ice, dust and gas from the crater and revealing pristine material beneath. The impact will have no significant affect on the orbit of Tempel 1, which poses no threat to Earth.

Nearby, Deep Impact’s “flyby” spacecraft will use its medium and high resolution imagers and infrared spectrometer to collect and send to Earth pictures and spectra of the event. The Hubble and Spitzer Space Telescopes, the Chandra X-ray Observatory, and large and small telescopes on Earth also will observe the impact and its aftermath.

The University of Maryland, College Park, conducts overall mission science for Deep Impact that is a Discovery class NASA program. NASA’s Jet Propulsion Laboratory handles project management and mission operations. The spacecraft was built for NASA by Ball Aerospace and Technologies Corporation, Boulder, Colo.

Original Source: NASA/JPL News Release

Artist illustration of SWAS. Image credit: CfA. Click to enlarge.
The Submillimeter Wave Astronomy Satellite (SWAS) has been asleep on orbit for the past 11 months. SWAS operators placed it into hibernation after a highly successful 5.5-year mission highlighted by the discovery of a swarm of comets evaporating around an aging red giant star. Now, they have awakened SWAS again for the first-ever opportunity to study a comet on a collision course with a U.S. space probe.

“We knew there was life left in SWAS,” said SWAS Principal Investigator Gary Melnick (Harvard-Smithsonian Center for Astrophysics). “SWAS’s ability to detect emission from water convinced us that we could contribute to the broader understanding of comets generated by this event. This once-in-a-lifetime event was just too tempting to pass up.”

NASA’s Deep Impact mission will rendezvous with Comet Tempel 1 at the end of June. Twenty-four hours before collision, on July 3rd, the flyby spacecraft will deploy a 39-inch long by 39-inch wide, 802-pound copper-reinforced impactor to strike the comet’s nucleus. As the main Deep Impact spacecraft watches from a safe distance, the impactor will blast material out of the comet, excavating a football stadium-sized crater of pristine ice from the interior. SWAS will measure the abundance of water molecules as the icy comet debris vaporizes.

“Because a comet is composed mostly of ice and rock, water is the most abundant molecule released by a comet. Everything else vaporizing from the comet is measured relative to the amount of water,” said Melnick. “Water is the gold standard for comets, so knowing how much water is being released per second is a very useful piece of information.”

Current SWAS measurements indicate that Comet Tempel 1 is ejecting about 730 pounds of water per second, which is modest by cometary standards. Deep Impact mission designers specifically selected the target for this reason because the probe’s mothership will have a better chance of surviving the flyby. SWAS will watch closely for any changes to the water production rate during and after the impact. Its measurements will help constrain the nature of the comet’s nucleus, including its chemical makeup.

NASA and the SWAS team decided to reawaken the satellite because it offers several unique advantages for observing the impactor-comet collision. SWAS can determine the water production rate directly. It has a large field of view that encompasses both the comet nucleus and the surrounding envelope of vaporized gases known as the coma. And, it is above the atmosphere and unaffected by weather, allowing SWAS to monitor the comet almost continuously.

In early June, the satellite was powered up and its components successfully tested. SWAS will remain active through the end of August, watching Comet Tempel 1 for any long-term changes.

“It’s gratifying that a satellite that has contributed so much during its lifetime has been given one more opportunity,” said Melnick. “Helping to decipher the composition of material thought to be unchanged since the birth of our solar system seems like a great last act.”

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: CfA News Release

Hubble view of a jet on Comet Tempel 1. Image credit: Hubble. Click to enlarge.
In a dress rehearsal for the rendezvous between NASA’s Deep Impact spacecraft and comet 9P/Tempel 1, the Hubble Space Telescope captured dramatic images of a new jet of dust streaming from the icy comet.

The images are a reminder that Tempel 1’s icy nucleus, roughly half the size of Manhattan, is dynamic and volatile. Astronomers hope the eruption of dust seen in these observations is a preview of the fireworks that may come July 4, when a probe from the Deep Impact spacecraft will slam into the comet, possibly blasting off material and giving rise to a similar dust plume.

These observations demonstrate that Hubble’s sharp “eye” can see exquisite details of the comet’s temperamental activities. The Earth-orbiting observatory was 75 million miles away from the comet when these images were taken by the Advanced Camera for Surveys’ High Resolution Camera. The telescope’s views complement close-up images being taken by cameras aboard Deep Impact, which is speeding toward the comet.

The two images, taken seven hours apart on June 14, show Tempel 1 and its new jet. The image at left, taken at 2:17 a.m. (EDT), is a view of the comet before the outburst. The bright dot is light reflecting from the comet’s nucleus, which appears star-like in these images because it is too small even for Hubble to resolve. The nucleus, a potato-shaped object, is 8.7 miles (14 kilometers) wide and 2.5 miles (4 kilometers) long. Hubble’s viewing the nucleus is as difficult as someone trying to spot a potato in Salt Lake City from New York City.

The photo at right, snapped at 9:15 a.m. (EDT), reveals the jet [the bright fan-shaped area]. The jet extends about 1,400 miles (2,200 kilometers), which is roughly half the distance across the U.S. It is pointing in the direction of the Sun. Comets frequently show outbursts in activity, but astronomers still don’t know exactly why they occur. Tempel 1 has been moving closer to the Sun, and perhaps the increasing heat opened up a crack in the comet’s dark, crusty surface. Dust and gas trapped beneath the surface could then spew out of the crack, forming a jet. Or, perhaps a portion of the crust itself was lifted off the nucleus by the pressure of heated gases beneath the surface. This porous crust might then crumble into small dust particles shortly after leaving the nucleus, producing a fan-shaped coma on the sunward side. Whatever the cause, the new feature may not last for long.

Astronomers hope that the July 4 collision will unleash more primordial material trapped inside the comet, which formed billions of years ago. Comets are thought to be “dirty snowballs,” porous agglomerates of ice and rock that dwell in the frigid outer boundaries of our solar system. Periodically, they make their journey into the inner solar system as they loop around the Sun.

The contrast in these images has been enhanced to highlight the brightness of the new jet.

Original Source: Hubble News Release

Deep Impact’s first view of Comet Temple 1 from a distance of 64 million kilometers (39.7 million miles). Image credit: NASA/JPL. Click to enlarge.
Sixty-nine days before it gets up-close-and-personal with a comet, NASA’s Deep Impact spacecraft successfully photographed its quarry, comet Tempel 1, from a distance of 64 million kilometers (39.7 million miles).

The image, the first of many comet portraits it will take over the next 10 weeks, will aid Deep Impact’s navigators, engineers and scientists as they plot their final trajectory toward an Independence Day encounter. “It is great to get a first glimpse at the comet from our spacecraft,” said Deep Impact Principal Investigator Dr. Michael A’Hearn of the University of Maryland, College Park, Md. “With daily observations beginning in May, Tempel 1 will become noticeably more impressive as we continue to close the gap between spacecraft and comet. What is now little more than a few pixels across will evolve by July 4 into the best, most detailed images of a comet ever taken.”

The ball of dirty ice and rock was detected on April 25 by Deep Impact’s medium resolution instrument on the very first attempt. While making the detection, the spacecraft’s camera saw stars as dim as 11th visual magnitude, more than 100 times dimmer than a human can see on a clear night.

“This is the first of literally thousands of images we will take of Tempel 1 for both science and navigational purposes,” said Deputy Program Manager Keyur Patel at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Our goal is to impact a one-meter long (39-inch) spacecraft into about a 6.5-kilometer wide (4-mile) comet that is bearing down on it at 10.2 kilometers per second (6.3 miles per second), while both are 133.6 million kilometers (83 million miles) away from Earth. By finding the comet as early and as far away as we did is a definite aid to our navigation.”

To view the comet image on the Internet, visit http://www.nasa.gov/deepimpact or http://deepimpact.jpl.nasa.gov/.

Deep Impact is comprised of two parts, a “flyby” spacecraft and a smaller “impactor.” The impactor will be released into the comet’s path for a planned high-speed collision on July 4. The crater produced by the impact could range in size from the width of a large house up to the size of a football stadium and from 2 to 14 stories deep. Ice and dust debris will be ejected from the crater, revealing the material beneath.

The Deep Impact spacecraft has four data collectors to observe the effects of the collision – a camera and infrared spectrometer comprise the high resolution instrument, a medium resolution instrument, and a duplicate of that camera on the impactor (called the impactor targeting sensor) that will record the vehicle’s final moments before it is run over by comet Tempel 1 at a speed of about 37,000 kilometers per hour (23,000 miles per hour).

The overall Deep Impact mission management for this Discovery class program is conducted by the University of Maryland. Deep Impact project management is handled by the Jet Propulsion Laboratory. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo.

For more information about Deep Impact on the Internet, visit NASA Deep Impact.

Original Source: NASA/JPL News Release

Image credit: ESA
One of the ingenious instruments on board Rosetta is designed to ?smell? the comet for different substances, analysing samples that have been ?cooked? in a set of miniature ovens.

ESA?s Rosetta will be the first space mission ever to land on a comet. After its lander reaches Comet 67P/Churyumov-Gerasimenko, the main spacecraft will follow the comet for many months as it heads towards the Sun.

Rosetta’s task is to study comets, which are considered the primitive building blocks of the Solar System. This will help us to understand if life on Earth began with the help of ‘comet seeding’.

The Ptolemy instrument is an ?Evolved Gas Analyser?, the first example of a new concept in space instruments, devised to tackle the challenge of analysing substances ?on location? on bodies in our Solar System.

Weighing just 4.5 kilograms and about the size of a shoe box, it was produced by a collaboration of the UK?s Rutherford Appleton Laboratory and Open University.

The analysis of these samples from the surface of the comet will establish what the cometary nucleus is made from, providing valuable information about these most primitive objects.

After the lander touches down on the comet, the Ptolemy instrument will collect comet nucleus material, believed to be a frozen mixture of ices, dust and tar, using the Sampling, Drilling and Distribution system (SD2) supplied by Tecnospazio Milano of Italy. SD2 will drill for small cores of ice and dust from depths of down to 250 millimetres.

Samples collected in this way will be delivered to one of four tiny ?ovens? dedicated to Ptolemy, which are mounted on a circular, rotatable carousel. The German-supplied carousel has 32 of these ovens, with the remainder being used by other Rosetta instruments.

Of the four Ptolemy ovens, three are for solid samples collected and delivered by SD2 while the fourth will be used to collect volatile materials from the near-surface cometary atmosphere.

By heating the solid samples to 800 ?C, the oven converts them into gases which then pass along a pipe into Ptolemy. The gas will then be separated into its constituent chemical species using a gas chromatograph.

Ptolemy can then determine which chemicals are present in the comet sample, and hence help to build up a detailed picture of what the comet is made from.

It does this using the world?s smallest ?ion-trap mass spectrometer?, a small, low-power device built with the latest miniature technology. This device will find out what gases are present in any particular sample and measure stable isotope ratios.

Original Source: ESA News Release

Image credit: ESA
ESA’s comet-chaser Rosetta, whose 10-year journey to its final target Comet 67P/Churyumov-Gerasimenko started on 2 March, is well on its way. The first phase of commissioning is close to completion and Rosetta has successfully performed its first scientific activity – observation of Comet Linear.

The commissioning activities, which started a couple of days after launch, included the individual activation of all instruments on board the Rosetta orbiter and the Philae lander. This first check-out worked flawlessly and showed that the spacecraft and all instruments are functioning well and in excellent shape.

The commissioning tests also paved the way for Rosetta’s first scientific activity: observation of Comet C/2002 T7 (LINEAR), which is currently travelling for the first and only time through the inner Solar System and offered Rosetta an excellent opportunity to make its first scientific observation.

On 30 April, the OSIRIS camera system, which was scheduled for commissioning on that date, took images of this unique cometary visitor. Later that day, three more instruments on board Rosetta (ALICE, MIRO and VIRTIS) were activated in parallel to take measurements of the comet. Although the parallel activation of the instruments was not planned until later in the year, the Rosetta team felt confident that this could be done without any risk because of the satisfactory progress of the overall testing.

The first data from the remote-sensing observations confirm the excellent performance of the instruments. The four instruments took images and spectra of Comet C/2002 T7 (LINEAR) to study its coma and tail in different wavelengths, from ultraviolet to microwave. Rosetta successfully measured the presence of water molecules in the tenuous atmosphere around the comet. Detailed analysis of the data will require the complete calibration of the instruments, which will take place in the coming months. The OSIRIS camera produced high-resolution images of Comet C/2002 T7 (LINEAR) from a distance of about 95 million kilometres. The image (above) showing a pronounced nucleus and a section of the tenuous tail extending over about 2 million kilometres was obtained by OSIRIS in blue light.

The successful observation of Comet Linear was a first positive test for Rosetta’s ultimate goal, Comet 67P/Churyumov-Gerasimenko, which will be reached in 2014. Rosetta will be the first mission to undertake a long-term exploration of a comet at close quarters whilst accompanying it on its way towards the Sun.

The unprecedented in-depth study conducted by the Rosetta orbiter and its Philae lander will help scientists decipher the formation of our Solar System around 4600 million years ago and provide them with clues of how comets may have contributed to the beginning of life on Earth. In particular, the Philae lander, developed by a European consortium under the leadership of the German Aerospace Research Institute (DLR), will analyse the composition and structure of the comet’s surface.

After Rosetta’s first deep-space manoeuvres were carried out on 10 and 15 May with the highest accuracy, the first phase of commissioning is set to be completed in the first week of June. Rosetta will then go into a quiet ?cruise mode? until September, when the second phase of commissioning is scheduled to start. These activities, including the interference and pointing campaign, will last until December.

So the Rosetta spacecraft is well under way on its epic 10-year voyage, to do what has never before been attempted ? orbiting and landing on a comet.

Original Source: ESA News Release