Posted on by Fraser Cain

Venus Express Nearly Ready to Launch

Venus Express on top of its launcher. Image credit: ESA. Click to enlarge.
Following the announcement of the Venus Express launch delay due to particulate contamination found in the launcher fairing where the spacecraft was installed, ESA staff and industry teams have started an inspection of the spacecraft. This recovery ‘investigation procedure’ has so far revealed a spacecraft in good status.

Having been removed from the Soyuz rocket, the upper composite, consisting of the Venus Express spacecraft attached to the Fregat upper stage and all housed in the rocket fairing, was transported to the Baikonur cosmodrome’s Upper Composite Integration Facility in the early morning of Sunday 23 October. On Monday 24 October the fairing was removed and engineers started the inspection to assess the status of the spacecraft.

The scenario is so far very encouraging, as only fairly large particles, pieces of the insulating material initially covering the launcher’s Fregat upper stage, have been found on the body of the spacecraft. These have been easy to identify by naked eye or with UV lamps, and are being carefully removed with tweezers, vacuum-cleaners or nitrogen gas airbrushes, according to size.

In the next couple of days the inspections and cleaning of Venus Express will continue, focussing on the instrument optics and apertures. After this step, Venus Express will be ready for the electric tests, routine checks that precede the final cleaning done just before the encapsulation with the fairing. The upper composite will then be complete again and will be ready for re-integration with the launcher.

ESA and Starsem, the company responsible for the Soyuz-Fregat launcher, are merging the results of their parallel investigations and recovery measures to define a new launch date in the shortest time frame. The ESA Project team is confident that Venus Express will be launched well within the launch window, which closes on 24 November this year.

Original Source: ESA News Release

Posted on by Fraser Cain

What’s Up This Week – October 24 – October 30, 2005

NGC 204. Image credit: Todd Boronson NOAO/AURA/NSF. Click to enlarge.
Monday, October 24 – With the Moon well out of the way, the return of dark skies favours having a look at an incredible southern galaxy in Sculptor – NGC 253.

Located about one third the way between Alpha Sculptor and Beta Ceti, NGC 253 was discovered by Caroline Herschel in 1783 during a comet search. As the brightest member of the “Sculptor Group”, this large and beautiful galaxy is also one of the closest outside our “Local Group” and will be readily apparent in binoculars for southern observers. Mid-to-large telescopes will be delighted with its many bright knots and dark obscured areas. For more northern observers, wait until the constellation is at its highest to catch a glimpse of this awesome 7th magnitude southern study.

Today in 1851, another astronomer was busy at the eyepiece as William Lassell discovered Uranus’ moons Ariel and Umbriel. Although this is far beyond backyard equipment, we can have a look at the blue/green planet. Now around magnitude 5.5, Uranus can be spotted in even small binoculars, but it will be harder to find it than it will be to see it! Start in Aquarius northeast of Sigma while waiting on Sculptor to rise…

Tuesday, October 25 – And who was watching the planets in 1671? None other than Giovanni Cassini – because he’d just discovered Saturn’s moon Iapetus. Before dawn this morning, look for Saturn about half a fist-width below below the Moon. You just might catch Iapetus very close to the rings.

If you feel like another planet challenge, then head towards open western horizons because Mercury is also making a dim appearance. About a half hour after sunset, go out and start with Venus. Using binoculars, identify Antares less than a handspan lower to the west. Scan directly below Antares for this elusive planet so near the horizon.

Today is the birthday of Henry Norris Russell. Born in 1877, Russell was the American leader in establishing the modern field of astrophysics. As he namesake for the American Astronomical Society’s highest award (for a lifetime contribution to the field), Mr. Russell is the “R” in HR diagrams, along with Mr. Hertzsprung. This work was first used in a 1914 paper, published by Russell.

What is an H-R diagram? Like people – stars grow up and age. But unlike humans, they are all very different in terms of size and weight at their beginnings. Massive stars live short lives and put out a lot of light. Low mass stars are very dim but continue to glow for billions of years. Our Sun is low mass star, but in the end it will do what most stars do – swell up to enormous size. It will turn red, expend its fuel, then expire. What’s left will be a very small white dwarf – glowing mostly by stored up heat. H-R diagrams pull all these factors together – young stars, old stars, bright stars, and dim stars.

Let’s look at Antares. It’s a relatively old, massive star – very bright and destined to end brilliantly. Or Markab – an aging blue dwarf soon to become a red giant. Now look at Deneb. It’s a supermassive blue giant shining as brightly as some globular clusters – yet fated to create another supernova remnant in Cygnus within 100 thousand years… Take a look at Enif – a spectral class K orange supergiant radiating with as much light as 7000 suns – yet it burns fast and is cooler than Sol. How about Polaris? Hotter than Sol, it’s another star about to enter a glorious retirement. Thankfully, our Sun is right in the middle of the wonderful H-R diagram!

Wednesday, October 26 – Tomorrow Neptune ends its retrograde, or westward, journey across the sky and will slowly begin to travel east. At 8th magnitude, it’s within binocular range and can be found west of Theta Capricornii.

Tonight let’s go hunting for the “Blue Snowball”. It’s proper name is the NGC 7622 and you find it around five degrees due east of Omicron Andromedae. At magnitude 9, this one challenges binocular users and presents the same problems as locating the M57 – low power will show you something – but not what it is. In a telescope, the “Blue Snowball” is almost as large as the “Ring” nebula.

Thursday, October 27 – This morning, look for the crescent Moon as it visits in Leo and makes a grand appearance with Regulus.

For those of you with larger telescopes who are looking for a real challenge, try your hand at roughly 10th magnitude comet C/2005 E2 McNaught. Now cruising just southwest of star 62 Sagittarius, look for what appears to be a faded and unresolved globular cluster.

Something a bit brighter? Then try your hand at asteroid 89 Julia. At magnitude 9.4, you’ll find it around 600 light seconds away just north of Beta Andromedae. You’ll find excellent locator charts at Heaven’s Above.

Friday, October 28 – Today in 1971, Great Britain launched its first satellite. For our friends in Russian, you will have a chance to see the Moon occult Sigma Leonis on this universal date. Please check with IOTA for more details.

Within the next 24 hours, Mars and Earth come will come the closest for this year. At some 43 million miles away, it doesn’t appear much like the size of the Full Moon, does it? Every two years we pass each other in our orbit around the Sun, and although we aren’t as close as we were in 2003, it will be another 13 years before we’re this near again.

Don’t leave your telescope inside. Don’t worry if you only use binoculars or just your eyes. Mars is simply superb right now and you cannot miss it’s ruddy color. For many of you, one of the largest and most easily spotted features, Syrtis Major, will now be in plain view. Appearing much light a deep, dark triangle, look closely for the lighter oval of Hellas Basin towards the pole. Still, others may see Mare Cimmerium, looking much like an antler – or Mare Erythraerum whose “fingers” reach toward Chryse. No matter where you are, wait until Mars is well risen for the very best views and enjoy!

Saturday, October 29 – On this night in 1749, French astronomer Le Gentil was at the eyepiece of an 18′ focal length telescope. His object of choice was the Andromeda Galaxy, which he believed to be a nebula. Little did he know at the time, his descriptive notes also included the M32, a satellite galaxy of the M31. It was the first small galaxy discovered and it would be another 175 years before they were recognized by Edwin Hubble as such.

Perhaps where you live, tonight will also be celebrated as “trick or treat”. If so, why not give your tricksters a real treat and view the Andromeda Galaxy? Be sure to take the time to look for both the M32 and M110 – both are fine galaxies in their own right. If skies are too light, put bright Alberio in the eyepiece!

Sunday, October 30 – Tonight let’s head toward an early evening study as we take a look at the departing M57. Located almost centrally between Beta and Gamma Lyrae, the “Ring” will appear as an out-of-focus “star” in the populated field for binoculars and resolve into its namesake for even the smallest of telescopes. This round shell of gas surrounding an expiring star will make a excellent conversation piece for any “Halloween” party.

Before you leave, take another look at Mars. Still a week away from opposition, right now is the best time to let it rise high to catch a stable look at the surface features.

I would also like to thank Jeff Barbour for his input this week. We’re all just a little bit closer… Under the stars! Until next week? May all your journeys be at light speed… ~Tammy Plotner

Posted on by Fraser Cain

Podcast: Astrophotography with Tom Davis

My guest today is an amateur astrophotographer named Tom Davis. Those of you who subscribe to the Universe Today newsletter should be familiar with his photographs, as I’ve featured several of them in the last few months. Tom is an amazingly skilled astrophotographer, and he’s got some decent equipment. And I’m happy to inform you that the price for this kind of technology is more affordable than it’s every been, so if you’ve ever wanted to get into this hobby, maybe you’ll get inspired. Before you start listening, please take a moment to look at his website at: http://www.tvdavisastropics.com.
Continue reading “Podcast: Astrophotography with Tom Davis”

Posted on by Fraser Cain

Podcast: Astrophotography with Tom Davis

Horsehead Nebula by Tom Davis.
Listen to the interview: Astrophotography with Tom Davis (6.1 MB)

Or subscribe to the Podcast: universetoday.com/audio.xml

Fraser Cain: This is going to be one of those podcasts where I think people are going to want to sit in front of their computer at some point and take a look at your photographs, so just to let everyone know, I’m going to have them point their browser at http://www.tvdavisastropics.com. And so I recommend you get this up in your browser before you listen to the rest of the show because talking about astrophotos is kind of like dancing about architecture (to steal a phrase). Now Tom Davis, you’ve got some amazing pictures, and you’re an amateur photographer out of Idaho. Can you explain the setup you’ve got?

Tom Davis: I have a dome; it’s a clamshell dome in my front yard, and I live on the side of a mountain at about 5,700 feet above sea level. And in that dome – it’s a 7-foot dome – I have a pier, and on the pier is an Astrophysics 1200 GTO mount, which is an outstanding mount. And on the mount, I have a couple different variety of setups. Currently I have an Astrophysics 155 EDF refractor, and on top of that, riding piggyback is an Astrophysics 105 EDF f6 traveller refractor. And I use the traveller as a guide scope. The two cameras I use predominantly are both made by the Santa Barbara Imaging Group (SBIG). One is the STL 11000M; that’s the monochrome version. And then the other is the ST 10 XME. They’re both very sensitive cameras; they both do different things. Certainly the STL 11000 has a much wider field of view, and it’s an anti-blooming gate camera, which means the stars won’t get those funny spikes that you often see. It’s not quite as sensitive in the red spectrum, particularly hydrogen alpha, but it does a marvelous job, nonetheless. And certainly the ST10 is one of SBIG’s most sensitive and flagship cameras. So that’s what I have.

I have a computer in the dome. It sits on a little shelf, and it’s the computer that I have on a wireless system, and I actually sit in my kitchen when I image. I have a laptop in there that I’m actually looking at right now. Through the wireless network using real VNC, I can run the telescope and everything just from inside my house, so it’s awfully nice in the Winter.

Fraser: I was about to say that. It must get pretty cold there at that altitude.

Davis: It gets very cold at this altitude, but everything runs fine. People who live in really cold climates wonder if their camera’s going to run, or if their mount is going to run, or is it going to hurt the telescope, and the answer to that is absolutely not. With some very simple precautions, everything runs great. I’ve been imaging down even to -20 degrees.

Fraser: What kind of investment have you put in to get yourself to the level of equipment that you’ve got today?

Davis: Well, this hobby, obviously can require a lot of money – 10s of thousands of dollars. Certainly that’s where I am at with this investment. However, for people who want to just start imaging with CCD, the cameras nowadays are so affordable, and far better than the cameras that I first started out with. Literally they can get very good images for a couple of thousand dollars. Even simple telescopes, such as a simple refractor. Even if it’s not one of the high-end ones, and a simple camera, can give you very good images that a lot of people would be absolutely delighted to take. So yes, it’s one of those high-end hobbies, unfortunately, it does require a lot of money once you really get into it. But I highly encourage anyone, any amateur, any visual astronomer out there – if they’re interested at all – now is the time to get into imaging; the software is much better to get into, the mounts, the telescopes, and even the cameras are just phenomenal now.

Fraser: Yeah, that’s been my impression in seeing the quality of the astrophotos that amateurs are taking. I just seemed like in the last couple of years, the photos sent in have just blown me away. And so, what kinds of advancements have been made in the last little while that’s made this so possible?

Davis: Well I think the biggest thing is the understanding that to get really high quality images, you need to put a lot of time into your image. The film astroimager would take 50 minutes to an hour open shutter images, and then take two or three of those and then combine them. Well, in CCD imaging, you don’t do that. Essentially we take subframes. Typically 5-10 minutes, maybe 20-25 minutes at the most on specific narrow band filters like a hydrogen alpha. And you take a whole series of those or 6 or 7 or 10, and then digitally you stack them. In the past we were just so thrilled with the images that we were getting, we were only shooting total imaging times of maybe an hour to 1.5 hours, and those were great images. The one thing interesting about CCD imaging is that the more time that you spend taking – in other words, more data, more photos you’re actually registering – the better the quality the image, and the less noise that comes from the sky. One of the main things that you’ve been seeing over these last couple of years is that most of us now don’t image for the average object, let’s say an average nebula, we really don’t image for anything less than 3 to 3.5 hours now. And so it’s a lot of time, sometimes over multiple nights, but when you stack all that data, the noise really reduces quite dramatically, and you start seeing these really beautiful and beautifully detailed images. I think the other thing that has really advanced, at least amateur astroimaging with CCD cameras, are large diameter telescopes. Now the largest I have right now is a 10″, I have a Takahashi BRC 250, which is a Ritchie Chretien type telescope. I haven’t really imaged with it much because I’ve been doing things mainly with the Astrophysics, but this Winter I’ll start using the Takahashi. A lot of guys have Ritchie Chretiens that are now 12.5″ or 14″ or 16″, and even one guy that has a 32″. These are amateurs and that aperture of telescope used to only be in the realm of professionals, well now some guys have those sizes of telescopes. Unfortunately, that style of telescope, the optical design is extraordinarily expensive and so it really limits for just everybody to buy that. But those two things are the main things. And then finally the camera technology; really the cameras and many of the chips are similar to what we’ve had in the past, but now we have much larger chips – similar sensitivity but they’re much larger, like this STL. It’s really opened up some beautiful vistas we can take.

Fraser: And do you find that your telescope and imaging setup can contribute to science as well?

Davis: Oh absolutely. The average amateur with a 6″ telescope and a CCD chip can do phenomenal science. I freely admit that I’m not a scientist, and I don’t think that my images are scientific quality. They like a certain type of data, but yes. If you were taking images of galaxies, you can discover new supernovae; we recently saw that in the Whirlpool Galaxy, an amateur discovering that. I’ve recently taken a picture this summer of M31 and was able to compare it to some of the pictures taken from the Palomar surveys of past, and I can actually pick out the Cephied variables of M31, and globular clusters around M31 just off of my image, my 6″ refractor. And if I wanted to do Cephied variables from M31, I could actually do that, so without question. There’s even been a couple of amateurs who have discovered new extra solar system planets with small telescopes, using the right software and having that right savvy to watch the data, so absolutely. The amateur now is able to contribute to science and many of the professional astronomers are going into collaboration with amateurs, and so it’s very exciting, not just pretty pictures, but you can actually get scientifically worth data.

Fraser: It sounds like a great time to be taking these photos.

Davis: Absolutely, it’s a great time for anyone who really wants to image, they can get in. You can get CCD cameras now – they are expensive, but you can get used cameras and take some very very nice pictures, and see more detail in a 60 second simple monochrome picture of, let’s say, M42 than you can in an eyepiece if you just have an ordinary aperture telescope. So it is a very exciting time.

Posted on by Fraser Cain

Mars Once Had Plate Tectonics

Crustal magnetism readings across Mars. Image credit: NASA/JPL. Click to enlarge.
NASA scientists have discovered additional evidence that Mars once underwent plate tectonics, slow movement of the planet’s crust, like the present-day Earth. A new map of Mars’ magnetic field made by the Mars Global Surveyor spacecraft reveals a world whose history was shaped by great crustal plates being pulled apart or smashed together.

Scientists first found evidence of plate tectonics on Mars in 1999. Those initial observations, also done with the Mars Global Surveyor’s magnetometer, covered only one region in the Southern Hemisphere. The data was taken while the spacecraft performed an aerobraking maneuver, and so came from differing heights above the crust.

This high resolution magnetic field map, the first of its kind, covers the entire surface of Mars. The new map is based on four years of data taken in a constant orbit. Each region on the surface has been sampled many times. “The more measurements we obtain, the more accuracy, and spatial resolution, we achieve,” said Dr. Jack Connerney, co-investigator for the Mars Global Surveyor magnetic filed investigation at NASA’s Goddard Space Flight Center, Greenbelt, Md.

“This map lends support to and expands on the 1999 results,” said Dr. Norman Ness of the Bartol Research Institute at the University of Delaware, Newark. “Where the earlier data showed a “striping” of the magnetic field in one region, the new map finds striping elsewhere. More importantly, the new map shows evidence of features, transform faults, that are a “tell-tale” of plate tectonics on Earth.” Each stripe represents a magnetic field pointed in one direction­positive or negative­and the alternating stripes indicate a “flipping” of the direction of the magnetic field from one stripe to another.

Scientists see similar stripes in the crustal magnetic field on Earth. Stripes form whenever two plates are being pushed apart by molten rock coming up from the mantle, such as along the Mid-Atlantic Ridge. As the plate spreads and cools, it becomes magnetized in the direction of the Earth’s strong global field. Since Earth’s global field changes direction a few times every million years, on average, a flow that cools in one period will be magnetized in a different direction than a later flow. As the new crust is pushed out and away from the ridge, stripes of alternating magnetic fields aligned with the ridge axis develop. Transform faults, identified by “shifts” in the magnetic pattern, occur only in association with spreading centers.

To see this characteristic magnetic imprint on Mars indicates that it, too, had regions where new crust came up from the mantle and spread out across the surface. And when you have new crust coming up, you need old crust plunging back down­the exact mechanism for plate tectonics.

Connerney points out that plate tectonics provides a unifying framework to explain several Martian features. First, there is the magnetic pattern itself. Second, the Tharsis volcanoes lie along a straight line. These formations could have formed from the motion of a crustal plate over a fixed “hotspot” in the mantle below, just as the Hawaiian islands on Earth are thought to have formed. Third, the Valles Marineris, a large canyon six times as long as the Grand Canyon and eight times as deep, looks just like a rift formed on Earth by a plate being pulled apart. Even more, it is oriented just as one would expect from plate motions implied by the magnetic map.

“It’s certainly not an exhaustive geologic analysis,” said Dr. Mario Acuña, principal investigator for the Mars Global Surveyor magnetic filed investigation at Goddard Space Flight Center. “But plate tectonics does give us a consistent explanation of some of the most prominent features on Mars.”

Results were published in the Oct. 10 edition of the Proceedings of the National Academy of Science.

Other scientists working on the project included Dr. G. Kletetschka of the Catholic University of America, Washington, DC, and Goddard Space Flight Center; Dr. D.L. Mitchell and Dr. R.P. Lin of the University of California at Berkeley; and Dr. H. Reme of the Centre d’Etude Spatiale des Rayonnements in France. Dr. Acuña leads the international team that built and operates the Mars Global Surveyor magnetometers. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington.

Original Source: NASA News Release

Posted on by Fraser Cain

Planets Could Be Common Around Brown Dwarfs

Artist illustration of microscopic crystals surrounding a dusty disk. Image credit: NASA/JPL. Click to enlarge.
NASA’s Spitzer Space Telescope has spotted the very beginnings of what might become planets around the puniest of celestial orbs – brown dwarfs, or “failed stars.”

The telescope’s infrared eyes have for the first time detected clumps of microscopic dust grains and tiny crystals orbiting five brown dwarfs. These clumps and crystals are thought to collide and further lump together to eventually make planets. Similar materials are seen in planet-forming regions around stars and in comets, the remnants of our own solar system’s construction.

The findings provide evidence that brown dwarfs, despite being colder and dimmer than stars, undergo the same initial steps of the planet-building process.

“We are learning that the first stages of planet formation are more robust than previously believed,” said Dr. Daniel Apai, an astronomer at the University of Arizona, Tucson, and member of the NASA Astrobiology Institute’s Life and Planets Astrobiology Center. “Spitzer has given us the possibility to study how planets are built in widely different environments.”

The observations also imply that brown dwarfs might be good targets for future planet-hunting missions. Astronomers do not know if life could exist on planets around brown dwarfs.

Brown dwarfs differ from stars largely due to their mass. They lack the mass to ignite internally and shine brightly. However, they are believed to arise like stars, out of thick clouds of gas and dust that collapse under their own weight. And like stars, brown dwarfs develop disks of gas and dust that circle around them. Spitzer has observed many of these disks, which glow at infrared wavelengths.

Apai and his team used Spitzer to collect detailed information on the minerals that make up the dust disks of six young brown dwarfs located 520 light-years away, in the Chamaeleon constellation. The six objects range in mass from about 40 to 70 times that of Jupiter, and they are roughly 1 to 3 million years old.

The astronomers discovered that five of the six disks contain dust particles that have crystallized and are sticking together in what may be the early phases of planet assembling. They found relatively large grains and many small crystals of a mineral called olivine.

“We are seeing processed particles that are linking up and growing in size,” said Dr. Ilaria Pascucci, a co-author also of the University of Arizona. “This is exciting because we weren’t sure if the disks of such cool objects would behave the same way that stellar disks do.”

The team also noticed a flattening of the brown dwarfs’ disks, which is another sign that dust is gathering up into planets.

A paper on these findings appears online today in Science. Authors of the paper also include Drs. Jeroen Bouwman, Thomas Henning and Cornelis P. Dullemond of the Max Planck Institute for Astronomy, Germany; and Dr. Antonella Natta of the Osservatorio Astrofisico di Arcetri, Italy.

NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA’s Science Mission Directorate. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spitzer’s infrared spectrograph, which made the observations, was built by Cornell University, Ithaca, N.Y. Its development was led by Dr. Jim Houck of Cornell. The NASA Astrobiology Institute, founded in 1997, is a partnership between NASA, 16 major U.S. teams and six international consortia.

For artist concepts, graphics and more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer/ . For more information about the NASA Astrobiology Institute, visit http://nai.arc.nasa.gov/ . For more information about NASA and agency programs on the Web, visit http://www.nasa.gov/home/ .

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Middle Latitude Clouds on Titan Are Familiar

Saturn’s Moon Titan. Image credit: NASA/JPL/SSI. Click to enlarge.
University of Arizona scientists say that the peculiar clouds at middle latitudes in Titan’s southern hemisphere may form in the same way as distinct bands of clouds form at Earth’s equator.

“Titan’s weather is very different from Earth’s,” said UA associate professor Caitlin Griffith. “If you walked past Titan’s minus-40-degree-latitude line, you might be showered with liquid natural gas. If you decided to visit Titan’s south pole, you might encounter a storm the size of a hurricane which also consists of methane, more commonly known as natural gas,” Griffith said. “Otherwise, don’t expect clouds on Titan.”

Titan’s weather forecast has remained the same for years, and that baffles scientists. They don’t understand why clouds a thousand miles long stretch over the temperate latitude.

“Imagine how curious it would be if beyond Earth’s poles, clouds existed only at the latitude that crosses New Zealand, Argentina and Chile,” Griffith said. “Furthermore, Henry Roe (of the California Institute of Technology) and his colleagues find that most of these peculiar clouds bunch up at zero degrees and 90 degrees longitude, analogous to Earth longitudes southwest and southeast of the Cape of Good Hope,” she added.

The highly localized nature of the clouds suggests that they have something to do with Titan’s surface, Griffith said. Scientists think ice volcanoes must be venting methane — the gas that condenses as clouds — into Titan’s hazy, mostly nitrogen atmosphere. Otherwise, the moon’s atmospheric methane would have vanished billions of years ago because methane is destroyed by ultraviolet sunlight.

Griffith, Paulo Penteado and Robert Kursinski of UA’s Lunar and Planetary Lab studied the origin of the clouds by analyzing cloud height and thickness using images from Cassini’s visual and infrared mapping spectrometer (VIMS). This instrument is among a suite of instruments on the Cassini spacecraft orbiting Saturn. It measures light at 256 different wavelenghts. Griffith is a member of the UA-based VIMS team, headed by Robert Brown of UA’s Lunar and Planetary Lab. Griffith and her colleagues analyzed images that gave them a 3-D view of the cloud and a six-frame movie that shows how it evolved over three hours.

“The structure of the clouds turns out to be complicated,” Griffith said. “We detected not one region, but many regions of cloud formation. Each long cloud consists of a number of vigorous storms where clouds rise to 40 kilometers altitude (25 miles) in a couple of hours and dissipate in the next half hour. The rate of cloud ascent and dissipation suggests that we are witnessing the formation of convective clouds, likely similar to thunderstorms, that disappear through rainfall.

“Over the next several hours we see the clouds form long tails, indicating that strong westerly winds stretch out the clouds and carry the particles downwind a thousand kilometers (more than 600 miles). This detailed look into the structure of these clouds reveals that the clouds evolve from a number of small active cloud formation centers lined up like an uneven string of beads long 40 degrees south latitude. These localized storms cause a healthy rain, and very long clouds, once the wind has stretched them out.”

Griffith argues that it’s improbable that many ice volcanoes, all aligned at 40 degrees south latitude, are forming these clouds. In addition, the scientists estimate that the cloud activity at zero degrees longitude, if volcanic, does not appear to spew out enough methane to create the mid-latitude cloud band. Smaller clouds actually lie upwind of the main cloud at zero degrees longitude, they note. The team also conclude that the clouds aren’t obviously caused by Saturn’s tidal pull on Titan’s atmosphere. They also don’t find evidence that mountains and lakes might cause mountain clouds or marine clouds, Griffith said.

“We believe that it’s no coincidence that Titan’s south polar cap of smog extends from the pole to 40 degrees south latitude — exactly where the methane cloud band appears,” Griffith said. The researchers suggest that global circulation may cause the air to rise at this latitutude on Titan, much as clouds form in a band around the Earth’s equator and rain on the Caribbean islands. “Such rising air would cut off air from the south polar region from mixing with the rest of the moon’s atmosphere, causing smog to build up and form a cap over the pole,” Griffith added.

Theoretical modeling supports the UA team’s conclusion, Griffith said. Pascal Ranou and his group in Paris studied Titan’s circulation with an elaborate and complicated general circulation model. His model predicts that solar heating naturally creates rising air on Titan at 40 degrees south latitude.

The next mystery is why Titan’s southern mid-latitude clouds are bunched at zero degrees longitude. There’s no evidence yet that volcanoes, mountain ranges or Saturn’s tides are involved, Griffith said. “What’s causing the bunching is unclear, and likely involves unknown features on Titan’s still largely unexplored surface,” Griffith said.

Griffith, Kursinki and Penteado are publishing an article on their research in the Oct. 21 issue of Science.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at The University of Arizona in Tucson.

Original Source: University of Arizona News Release

Posted on by Fraser Cain

Final Titan 4 Launches

Final Titan 4 lifting off. Image credit: Lockheed Martin. Click to enlarge.
The United States Air Force and Lockheed Martin (LMT:NYSE) closed out a proud five-decade history today with the final launch of a Titan IV B rocket carrying a critical national security payload for the National Reconnaissance Office (NRO). All eyes were on Space Launch Complex 4 East as the nation’s heavy-lift workhorse thundered off the pad to deliver its final payload to space and retire from service.

“Today’s spectacular launch is a fitting way to say goodbye to Titan,” said G. Thomas Marsh, executive vice president of Lockheed Martin Space Systems Company. “The Lockheed Martin employees who have given their utmost efforts to the program over the years join with our Air Force and NRO customers, and the many other organizations that make up the Titan team, in expressing our great pride in this service to our country’s space program.”

Today’s launch was the last launch for the Titan IV and the culmination of a long evolution from the original Titan I intercontinental ballistic missile. In all, 39 Titan IVs have been launched – 12 Titan IVs have been launched from Vandenberg Air Force Base on the West Coast plus 27 more from the Cape Canaveral Air Force Station, Fla. The final Titan IV mission from Cape Canaveral was launched successfully April 29, 2005.

Col. Michael T. Baker, director, Launch Programs, Space and Missile Systems Center, Air Force Space Command, said, “The members of the System Program Office are extremely proud to be part of this historic launch. I am particularly honored to lead this SPO since Titan has been a part of my career since 1981. We have been confident from the beginning that the Titan team would deliver one final mission success for the nation.”

Following the Space Shuttle Challenger tragedy in 1986, when assured access to space became critical for the U.S. government, the Titan IV was developed as the booster used to launch the nation’s largest, heaviest and most critical payloads. Titan initial IV A design was followed by Titan IV B with a new generation of large solid rocket motors, state-of-the-art guidance and electronics and a new ground processing system.

“Today’s launch marks the end of an NRO Titan era but the beginning of the Titan Legend that will live on in the history of America’s space program,” said Col. Chip Zakrzewski, National Reconnaissance Office mission director.

Lockheed Martin Space Systems Company built the Titan IVs near Denver, Colo., under contract to the U.S. government. As prime contractor and systems integrator, the company built the first and second stages and provides overall program management and launch services. Other members of the Titan IV contractor team and their responsibilities include: GenCorp Aerojet Propulsion Division, Sacramento, Calif., liquid rocket engines; Alliant Techsystems, Magna, Utah, solid rocket motor upgrade; The Boeing Company, Huntington Beach, Calif., payload fairing; and Honeywell Space Systems, Clearwater, Fla., advanced guidance.

Original Source: Lockheed Martin News Release