Posted on by Fraser Cain

Deep Impact Made a Bright Flash

The brilliant flash of light created by Deep Impact as it smashed into Tempel 1. Image credit: NASA/JPL. Click to enlarge.
The hyper-speed demise of NASA’s Deep Impact probe generated an immense flash of light, which provided an excellent light source for the two cameras on the Deep Impact mothership. Deep Impact scientists theorize the 820-pound impactor vaporized deep below the comet’s surface when the two collided at 1:52 am July 4, at a speed of about 10 kilometers per second (6.3 miles per second or 23,000 miles per hour).

“You can not help but get a big flash when objects meet at 23,000 miles per hour,” said Deep Impact co-investigator Dr. Pete Schultz of Brown University, Providence, R.I. “The heat produced by impact was at least several thousand degrees Kelvin and at that extreme temperature just about any material begins to glow. Essentially, we generated our own incandescent photo flash for less than a second.”

“They say a picture can speak a thousand words,” said Deep Impact Project Manager Rick Grammier of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “But when you take a look at some of the ones we captured in the early morning hours of July 4, 2005 I think you can write a whole encyclopedia.”

At a news conference held later on July 4, Deep Impact team members displayed a movie depicting the final moments of the impactor’s life. The final image from the impactor was transmitted from the short-lived probe three seconds before it met its fiery end.

“The final image was taken from a distance of about 30 kilometers (18.6 miles) from the comet’s surface,” said Deep Impact Principal Investigator Dr. Michael A’Hearn of the University of Maryland, College Park. “From that close distance we can resolve features on the surface that are less than 4 meters (about 13 feet) across. When I signed on for this mission I wanted to get a close-up look at a comet, but this is ridiculous? in a great way.”

The Deep Impact scientists are not the only ones taking a close look at their collected data. The mission’s flight controller team is analyzing the impactor’s final hours of flight. When the real-time telemetry came in after the impactor’s first rocket firing, it showed the impactor moving away from the comet’s path.

“It is fair to say we were monitoring the flight path of the impactor pretty closely,” said Deep Impact navigator Shyam Bhaskaran of JPL. “Due to the flight software program, this initial maneuver moved us seven kilometers off course. This was not unexpected but at the same time not something we hoped to see. But then the second and third maneuvers put us right where we wanted to be.”

The Deep Impact mission was implemented to provide a glimpse beneath the surface of a comet, where material from the solar system’s formation remains relatively unchanged. Mission scientists hoped the project would answer basic questions about how the solar system formed, by providing an in-depth picture of 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 News Release

Posted on by Mark Mortimer

Book Review: Big Bang: The Origin of the Universe

I’ll declare this right from the start, Simon Singh is one of my favorite science writers. His two previous books, Fermat’s Enigma and The Code Book are excellent. Especially the Code Book, which I was a little nervous to read, but walked away with a very firm understanding of codes and codebreaking through the centuries.

With Big Bang, Singh starts right at the beginning of cosmology, as the ancient Greeks showed a surprising series of leaps of logic about the Solar System. They correctly understood that the Earth is a sphere, and estimated its size. They calculated the distance to the Moon, and even took a stab at guessing the distance to the Sun. Unfortunately, they developed an incorrect view of an Earth-centred Universe, where the Sun, stars and the planets orbit the Earth. As errors developed in their theory, the Earth-centred astronomers just made their model more complex to compensate.

The book goes on to present discoveries in cosmology, one after the other, from the Copernicus Sun-centred view to Edwin Hubble’s discovery that many distant “nebulae” are actually other galaxies, like our Milky Way. Hubble then went on to discover that these distant galaxies are actually speeding away from us. It’s this discovery, that our Universe is expanding, which led to the theory we now call the Big Bang.

The Big Bang is such a profound theory, and it’s even more amazing because it’s embraced by nearly everyone working in cosmology today. Thank the evidence for this. Singh tracks down each piece of evidence supporting the Big Bang: the abundance of hydrogen in the Universe, the discovery that galaxies are speeding away from us, and the cosmic microwave background radiation. He introduces the reader to the cast of characters involved in each discovery, and then leads us through the observations and breakthroughs that formed this piece of evidence. We also meet the challengers and understand their differing, and very valid, viewpoints.

While reading Big Bang, you get the sense the Singh wanted to get across how well supported a theory the Big Bang is. This isn’t some half-baked theory about the Universe; the cosmologists who developed the Big Bang made some dramatic predictions which have turned out to be supported by observation. Some of the most dramatic are the most recent, with the Wilkinson Microwave Anisotropy Probe, which mapped variations in the microwave background radiation with such exquisite detail to help explain variations of matter in the Universe – why there are clumps of matter, like galaxies, planets, and people, and not just a rapidly spreading mist of equally-spaced hydrogen.

As I was reading Big Bang, through, I kept noticing how quickly I was moving through the book, and how slowly the story was progressing. Not that I was bored, but I was amazed at how long it took for discoveries to be presented. Once there was only a sliver remaining, I realized that I had slightly misjudged what the book was going to be about. Singh essentially wraps up with the discovery of the cosmic microwave background radiation by Penzias and Wilson – case closed, that’s the story of the Big Bang.

I follow astronomy and cosmology on a daily basis, and I know the story isn’t over. There are many intriguing discoveries being made all the time, such as dark energy, dark matter, and inflationary cosmology. Singh gives each of these subjects little more than a sentence or two in an epilogue, and this is unfortunate. I would have liked to see him tackle these fascinating subjects with the same care and skill that he handled the rest of the book. Perhaps a sequel Simon?

If you’re interested in astronomy, and want to get a nice overview of the Big Bang, I highly recommend this book by Simon Singh. It’s easy to read and understand, and gives a great overview of the theory, the theorists, and the evidence.

Read more reviews or order a copy online from Amazon.com

Review by Fraser Cain

Posted on by Fraser Cain

Deep Impact Smashes Into Tempel 1

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

Posted on by Mark Mortimer

Book Review: Conflict in the Cosmos, Fred Hoyle’s Life in Science

Fred Hoyle climbed through the challenges of Britain during the inter-war years. His diligence to his primary schooling was poor to say the least. Playing hookey was the order of his day. However, fortune smiled on him. Through this and his own effort, he managed to achieve a number of scholarships that kept him advancing until he gained acceptance into Cambridge University. There followed a checkered career as he studied mathematics with special application to nuclear physics. He had a short diversion due to the second world war where he advanced the state of electronic warfare. After, he jumped into the field of astronomy with both feet. During the remainder of his life, Fred Hoyle advanced this field and contributed to many others, often as not, by leading the explorations.

Leading any field is a balancing act between divining the future and keeping up with current events. Here emotion comes to the fore and here is where Mitton concentrates his book. He shows how Fred Hoyle, being in theoretical astronomy, often came to grips with observational astronomers. Further, Mitton builds a feeling that Fred Hoyle was like a kettle constantly steaming. Continual requests for publication were countered by people not understanding, or believing or wanting his views presented. Apparently, during most of his career, Fred Hoyle was at odds with the Royal Astronomical Society even though he was a member for most of his life. As well, Mitton shows how he appears to have used the largess of Cambridge to pursue his own work. In particular, he was a mentor who was seldom present. When he was, he was so caught up in his own theories, he didn’t always give the attention graduate students deserved. The resulting picture is of a vibrant, thoughtful, and analytical mathematician at the top of his game.

Mitton’s biography includes a mix of both personal and technical aspects to Fred Hoyle’s life. We read of Friday lunches in dimly lit rooms little better than cloisters. Further along there are recounts to a remarkable passion for hiking. He achieved the Munro, a climbing of a collection of hills in Scotland over 914 metres. He drove fast cars, enjoyed conferences by the lakes in Northern Italy and championed a telescope in Australia. Mitton relies on Fred Hoyle’s own autobiography as well as many friends and acquaintances to ensure accuracy and detail in the recollections.

On the technical side, Mitton details contribution to radar such as the bending of beams along the curvature of the Earth. Nucleosynthesis, one of the main focuses of Fred Hoyle’s career, gets a detailed and historical recount. Added are accounts of collaborations with experts as well as competitions against others. Mitton presents the information in a smooth, qualitative manner so there is no worry of confusion. All in all, Mitton builds an excellent link between the people, their discoveries and knowledge of the day that is both enjoyable to read and enlightening in its own way.

The interesting mix of personalities and technical information works well. Chapters are loosely divided chronologically. However, as Fred Hoyle had his finger into so many pies, Mitton decided to collect information into subject areas and deal with them chronologically. Due to this, there is a fair amount of jumping around in time throughout the text. This isn’t unduly bothersome but the reader must stay aware. Given the details on radar, advanced cosmology, science fiction novels, movie scripting, and leading an international collaboration on siting and building an observatory, this book is more of an insight into Fred Hoyle’s technical contributions than his personality.

Fred Hoyle’s emotions drove him to advance our understanding of cosmology. His work as a theoretical astronomer and science communicator captured the imaginations of people. Simon Mitton in his biography Conflict in the Cosmos, Fred Hoyle’s Life in Science brings back the life of Fred Hoyle, including the people and some of the technical issues of a person at the top of their game. Emotions are free to everyone, perhaps reading this will entice you on your own search for understanding.

Read more reviews, or order copy online from Amazon.com.

Review by Mark Mortimer

Posted on by Fraser Cain

Largest Core in an Extrasolar Planet

Artist illustration of the planet orbiting the sun-like star HD 149026. Image credit: U.C. Santa Cruz. Click to enlarge.
NASA researchers recently discovered the largest solid core ever found in an extrasolar planet, and their discovery confirms a planet formation theory.

“For theorists, the discovery of a planet with such a large core is as important as the discovery of the first extrasolar planet around the star 51 Pegasi in 1995,” said Shigeru Ida, theorist from the Tokyo Institute of Technology, Japan.

When a consortium of American, Japanese and Chilean astronomers first looked at this planet, they expected one similar to Jupiter. “None of our models predicted that nature could make a planet like the one we are studying,” said Bun’ei Sato, consortium member and postdoctoral fellow at Okayama Astrophysical Observatory, Japan.

Scientists have rarely had opportunities like this to collect such solid evidence about planet formation. More than 150 extrasolar planets have been discovered by observing changes in the speed of a star, as it moves toward and away from Earth. The changes in speed are caused by the gravitational pull of planets.

This planet also passes in front of its star and dims the starlight. “When that happens, we are able to calculate the physical size of the planet, whether it has a solid core, and even what its atmosphere is like,” said Debra Fischer. She is consortium team leader and professor of astronomy at San Francisco State University, Calif.

The planet, orbiting the sun-like star HD 149026, is roughly equal in mass to Saturn, but it is significantly smaller in diameter. It takes just 2.87 days to circle its star, and the upper atmosphere temperature is approximately 2,000 degrees Fahrenheit. Modeling of the planet’s structure shows it has a solid core approximately 70 times Earth’s mass.

This is the first observational evidence that proves the “core accretion” theory about how planets are formed. Scientists have two competing but viable theories about planet formation.

In the “gravitational instability” theory, planets form during a rapid collapse of a dense cloud. With the “core accretion” theory, planets start as small rock-ice cores that grow as they gravitationally acquire additional mass. Scientists believe the large, rocky core of this planet could not have formed by cloud collapse. They think it must have grown a core first, and then acquired gas.

“This is a confirmation of the core accretion theory for planet formation and evidence that planets of this kind should exist in abundance,” said Greg Henry, an astronomer at Tennessee State University, Nashville. He detected the dimming of the star by the planet with his robotic telescopes at Fairborn Observatory in Mount Hopkins, Arizona.

Original Source: NASA News Release

Posted on by Fraser Cain

Hubble’s View of Deep Impact

Hubble’s view of the Deep Impact collision. Image credit: Hubble. Click to enlarge.
The NASA/ESA Hubble Space Telescope captured the dramatic effects of the collision early on 4 July between the Deep Impact impactor spacecraft and Comet 9P/Tempel 1.

This sequence of images shows the comet before and after the impact. The image at left shows the comet just minutes before the impact. The encounter occurred at 07:52 CEST (05:52 UT/GMT).

In the middle image, captured 15 minutes after the collision, Tempel 1 appears four times brighter than in the pre-impact photograph.

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.

Hubble continued to monitor the comet, snapping another image (at right) 62 minutes after the encounter. In this photograph, the gas and dust ejected during the impact are expanding outward in the shape of a fan.

The fan-shaped debris is travelling at about 1800 kilometres an hour, or twice as fast as the speed of a commercial jet. The debris extends about 1800 kilometres from the nucleus.

The potato-shaped comet is 14 kilometres wide and 4 kilometres long. Tempel 1’s nucleus is too small even for the Hubble telescope to resolve.

The visible-light images were taken by the high-resolution camera on Advanced Camera for Surveys instrument. The Hubble Space Telescope is a project of international co-operation between ESA and NASA.

Original Source: ESA/Hubble News Release

Posted on by Fraser Cain

What’s Up This Week – July 4 – July 10, 2005

The “Cat’s Eye” Nebula. Image credit: Chris Deforeit at Astrim. Click to enlarge.
Monday, July 4 – 1054 A.D. This is the suspected date when Chinese astronomers noted the supernova from which we know the remnants of today as M1, the “Crab Nebula”. While this incredible event marks a red letter day in astronomy history, another is in the making.

If everything goes successfully, Deep Impact will have already been released and the information pouring in. For most of us, tonight will be our first chance to view, but for the lucky astronomers in the extreme western Americas – you’ve beat us to it! Just 3.5 degrees east/northeast of Spica, the comet is speculated to rise to 6th magnitude as the debris cloud spreads. No one knows exactly how long this will last, but viewers around the globe will get their opportunity to witness this event with a backyard telescope over the next 24 hours. Be there! I wish you all the very best of skies for this event.

So, if we can’t see a supernova remnant like the M1, or watch explosion happen on a comet, then what else can we do tonight? I’ve got a great idea – let’s check out the “Cat’s Eye” – it’s the best of both worlds! The proper designation is NGC 6543 and it’s located about midway between Delta and Zeta Draconis. As one of the most complex of all the planetary nebulae, it rose to popularity with the awesome Hubble photo. Very similar to the “Helix” nebula, our blue-green friend is the ejecta of a dying (possible double) star. This colorful planetary sends its light to us from roughly 3200 light years away and was the very first to be studied spectroscopically.

At magnitude 8.8, the “Cat’s Eye” can be spotted in large binoculars but will appear almost stellar. Smaller telescopes at high power will make it out as a slight disc, while larger scopes reveal the central star and far more color. For those with a nebular filter and a large scope, the NGC 6543 is a real pleasure to study as the helical area takes on form. Enjoy!

Tuesday, July 5 – Today as the date changes, the Earth reaches aphelion its farthest point from the Sun for the year while – oddly enough – Comet 9/P Tempel 1 reaches perihelion. So where’s the comet?

For northern hemisphere binocular users, look for the point of light visible to the southwest at twilight. That’s Jupiter. As the sky darkens completely, bright Spica will appear to Jupiter’s southeast. By aiming your binoculars there and placing Spica to the right of the field of view, you should be able to spot a faint fuzzy – the comet! For telescope users, Tempel 1 will appear almost directly between both star 68 and Gamma Virginis. Although we cannot perfectly predict what will happen after Deep Impact, studies suggest the comet will brighten to around 6th magnitude. Even if it doesn’t seem particularly impressive to smaller equipment, remember… You are viewing history! This will be the first time mankind has ever been able to make an effect on an astronomical object that can be viewed by the amateur.

If skies are cloudy tonight, keep trying. The effect of Deep Impact may last for days – or even weeks. The comet will continue to move south slowly over the next two weeks when it will be just west of Gamma Virginis.

Wednesday, July 6 – With some help from Edmond Halley, today in 1687 Sir Isaac Newton published his Principia with his three laws of motion. Since New Moon occurred in the early morning hours, this means dark skies tonight and an opportunity to study.

Normally, we’d go galaxy hunting on a dark night such as this, but how about if we explore the wonderful world of low power? Start by locating the magnificent M13 and move about 3 degrees northwest. What you will find is a splendid loose open cluster of stars known as Dolidze/Dzimselejsvili (DoDz) 5 – and it looks much like a miniature of the constellation of Hercules. Just slightly more than 4 degrees to its east and just about a degree south of Eta Hercules is DoDz 6, which contains a perfect diamond pattern and an asterism of brighter stars which resembles the constellation of Saggitta.

Now we’re going to move across the constellation of Hercules towards Lyra. East of the “keystone” you will see a tight configuration of three stars – Omicron, Nu and Xi. About the same distance that separates these stars to the northeast you will find DoDz 9. Using minimal magnification, you’ll see a pretty open cluster of around two dozen mixed magnitude stars that are quite attractive. Now look again at the “keystone” and identify Lambda and Delta to its south. About midway between them and slightly to the southeast you will discover the stellar field of DoDz 8. The last is easy – all you need to do is know beautiful red/green double, Ras Algethi (Alpha). Move about 1 degree to the northwest to discover the star-studded open cluster – DoDz 7. These great open clusters are very much off the beaten path and will add a new dimension to your large binocular, or low power telescoping experiences.

Thursday, July 7 – Are you ready for a visual challenge? Then see if you can spot the ultra-slim crescent of the Moon tonight. Less than a fist’s width above the horizon, look about 45 minutes after sunset as Selene begins its showing with the planets.

Tonight let’s try two more open star cluster studies that can be done easily with large binoculars or a low power scope. The first is a rich beauty that lays in the constellation of Vulpecula, but is easier found by moving around 3 degrees southeast of Beta Cygni. Known as Stock 1, this stellar swarm contains around 50 or so members of varying magnitudes that you will return to often. The next is an asterism known as the “Coat Hanger”, but it is also known as Brocchi’s Cluster, or Collinder 399. Let the colorful double star – Albeiro (which can be split in binos) – be your guide as you move about 4 degrees to its south/southwest. You will know this cluster when you see it, because it really does look like a coat hanger! Enjoy its red stars.

Friday, July 8 – What a way to start the weekend! As the skies darken to twilight tonight, be sure to check out the western horizon as the tender Moon has risen above our planetary pair of Venus and Mercury. Loaded with “earthshine”, this should be a picture perfect evening.

If skies are clear, let’s try some open star clusters in Cygnus. Starting with Gamma, identify loose open involving Gamma named Dolidze (Do) 43. Move two degrees southwest and pick up Do 42. Do not confuse it with nearby M29 – for the two look very similar. For fans of the “Double Cluster” in Perseus, you’ll like the next as we move another half degree to the southwest along the body of Cygnus to discover Do 40 and Do 41. This pretty pair of open clusters can be placed in the same lower power field. By moving another half degree due west, you’ll find highly populated Do 39 and it is a double treat as well – the brighter clump of stars in the same low power field is IC 4996.

Saturday, July 9 – Tonight the Moon will be less than half a fist’s width away from the “heart of Leo”, Regulus. While you may need binoculars to spot the star, be sure to note both it and Venus’ position and watch over the next two weeks as they draw closer.

Tonight after the Moon sets, take out your binoculars again to view two bright open clusters. The first, Ruprecht 173 is about a degree northwest of Epsilon Cygnii. You’ll appreciate this heavily populated star cluster! The next is as easy as identifying the constellation of Lyra. Just southeast of bright Vega is a wonderful double for binoculars, Delta 1 and 2 – the easternmost of the top two stars in the lyre. This bright pair is part of an open cluster known as Stephenson 1.

Sunday, July 10 – Tonight let’s enjoy a quiet evening of lunar contemplation. A wonderful crater to watch over the coming days lay on the western edge of Mare Crisium – Proculus. Tonight you will see it as a bright ring, but it will soon develop a ray system as the terminator moves west. Another beautiful pair of craters are near the terminator in the northern quandrant of the lunar orb – Atlas and Hercules. They are a splendid sight in binoculars and scope users can easily spot interior craterlets in these old giants.

Even if you only follow Deep Impact virtually, please watch this spectacular event. We’ll be on hand for history! May all your journeys be at Light Speed… ~Tammy Plotner

Posted on by Fraser Cain

Deep Impact Releases Impactor

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

Posted on by Fraser Cain

Happy Canada Day!

Hi folks, it’s Canada Day today here, so I’m taking the day off . Universe Today will be back on Monday with plenty of fresh space news.

Fraser Cain
Publisher
Universe Today