Posted on by Fraser Cain

In the Shadow of Saturn’s Rings

Image credit: NASA/JPL/Space Science
Saturn?s rings cast threadlike shadows on the planet?s northern hemisphere. Note the translucent C ring and thin, outermost F ring. The image was taken with the narrow angle camera in visible light on May 10, 2004 at a distance of 27.2 million kilometers (16.9 million miles) from Saturn. Image scale is 162 kilometers (101 miles) per pixel. Contrast in the image was enhanced to aid visibility.

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, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Posted on by Fraser Cain

New Theory Proposed for Solar System Formation

Image credit: Hubble
Like most creation stories, this one is dramatic: we began, not as a mere glimmer buried in an obscure cloud, but instead amidst the glare and turmoil of restless giants.

Or so says a new theory, supported by stunning astronomical images and hard chemical analysis. For years most astronomers have imagined that the Sun and Solar System formed in relative isolation, buried in a quiet, dark corner of a less-than-imposing interstellar cloud. The new theory challenges this conventional wisdom, arguing instead that the Sun formed in a violent nebular environment – a byproduct of the chaos wrought by intense ultraviolet radiation and powerful explosions that accompany the short but spectacular lives of massive, luminous stars.

The new theory is described in a ?Perspectives? article appearing in the May 21 issue of Science. The article was written by a group of Arizona State University astronomers and meteorite researchers who cite recently discovered isotopic evidence and accumulated astronomical observations to argue for a history of development of the Sun, the Earth and our Solar System that is significantly different from the traditionally accepted scenario.

If borne out by future work, this vision of our cosmic birth could have profound implications for understanding everything from the size and shape of our solar system to the physical makeup of the Earth and the development of the chemistry of life.

?There are two different sorts of environment where low-mass stars like the Sun form,? explained ASU astronomer Jeff Hester, the essay’s lead author. ?In one kind of star-forming environment, you have a fairly quiescent process in which an undisturbed molecular cloud slowly collapses, forming a star here? a star there. The other type of environment in which Sun-like stars form is radically different. These are more massive regions that form not only low-mass stars, but luminous high-mass stars, as well.?

More massive regions are very different because once a high-mass star forms, it begins pumping out huge amounts of energy that in turn completely changes the way Sun-like stars form in the surrounding environment. ?People have long imagined that the Sun formed in the first, more quiescent type of environment,? Hester noted, ?but we believe that we have compelling evidence that this is not the case.?

Critical to the team’s argument is the recent discovery in meteorites of patterns of isotopes that can only have been caused by the radioactive decay of iron-60, an unstable isotope that has a half life of only a million and a half years. Iron-60 can only be formed in the heart of a massive star and thus the presence of live iron-60 in the young Solar System provides strong evidence that when the Sun formed (4.5 billion years ago) a massive star was nearby.

Hester’s coauthors on the Science essay include Steve Desch, Kevin Healy, and Laurie Leshin. Leshin is a cosmochemist and director of Arizona State University’s Center for Meteorite Studies. ?One of the exciting things about the research is that it is truly transdisciplinary, drawing from both astrophysics and the study of meteorites – rocks that you can pick up and hold in your hand – to arrive at a new understanding of our origins,? noted Leshin.

When a massive star is born, its intense ultraviolet radiation forms an ?HII region? – a region of hot, ionized gas that pushes outward through interstellar space. The Eagle Nebula, the Orion Nebula, and the Trifid Nebula are all well-known examples of HII regions. A shock wave is driven in advance of the expanding HII region, compressing surrounding gas and triggering the formation of new low-mass stars. ?We see triggered low-mass star formation going on in HII regions today,? said Healy, who recently completed a study of radio observations of this process at work.

The star does not have much time to get its act together, though. Within 100,000 years or so, the star and what is left of its small natal cloud will be uncovered by the advancing boundary of the HII region and exposed directly to the harsh ultraviolet radiation from the massive star. ?We see such objects emerging from the boundaries of HII regions,” Hester said. ?These are the ?evaporating gaseous globules’ or ?EGGs’ seen in the famous Hubble image of the Eagle Nebula.?

EGGs do not live forever either. Within about ten thousand years an EGG evaporates, leaving behind only the low-mass star and its now-unprotected protoplanetary disk to face the brunt of the massive star’s wrath. Like a chip of dry ice on a hot day, the disk itself now begins to evaporate, forming a characteristic tear-drop-shaped structure like the ?proplyds? seen in Hubble images of the Orion Nebula. ?Once we understood what we were looking at, we realized that we had a number of images of EGGs caught just as they were turning into proplyds,? said Hester. ?The evolutionary tie between these two classes of objects is clear.?

Within another ten thousand years or so the proplyd, too, is eroded away. All that remains is the star itself, surrounded by the inner part of the disk (comparable in size to our Solar System), which is able to withstand the continuing onslaught of radiation. It is from this disk and in this environment that planets may form.

The process leaves a Sun-like star and its surrounding disk sitting in the interior of a low density cavity with a massive star close at hand. Massive stars die young, exploding in violent events called ?supernovas.? When a supernova explodes it peppers surrounding infant planetary systems with newly synthesized chemical elements – including short-lived radioactive isotopes such as iron-60.

?This is where the meteorite data come in,? said Hester. ?When we look at HII regions we see that they are filled with young, Sun-like stars, many of which are known to be surrounded by protoplanetary disks. Once you ask the question, ?what is going to happen when those massive stars go supernova?’, the answer is pretty obvious. Those young disks are going to get enriched with a lot of freshly-made elements.?

?When you then pick up a meteorite and find a mix of materials that can only be easily explained by a nearby supernova, you realize that you are looking at the answer to a very longstanding question in astronomy and planetary science,? Desch added.

?So from this we now know that if you could go back 4.5 billion years and watch the Sun and Solar System forming, you would see the kind of environment that you see today in the Eagle or Trifid nebulas,? said Hester.

?There are many aspects of our Solar System that seem to make sense in light of the new scenario,? notes Leshin. ?For example, this might be why the outer part of the Solar System – the Kuiper Belt – seems to end abruptly. Ultraviolet radiation would also have played a role in the organic chemistry of the young solar system, and could explain other peculiar effects such as anomalies in the abundances of isotopes of oxygen in meteorites.?

One of the most intriguing speculations is that the amount of radioactive material injected into the young solar system by a supernova might have profoundly influenced the habitability of Earth itself. Heat released by the decay of this material may have been responsible for ?baking out? the planetesimals from which the earth formed, and in the process determining how much water is on Earth today.

?It is kind of exciting to think that life on Earth may owe its existence to exactly what sort of massive star triggered the formation of the Sun in the first place, and exactly how close we happened to be to that star when it went supernova,? mused Hester. ?One thing that is clear is that the traditional boundaries between fields such as astrophysics, meteoritics, planetary science, and astrobiology just got less clear-cut. This new scenario has a lot of implications, and makes a lot of new predictions that we can test.?

If it is accepted, the new theory may also be of use in looking for life in the universe beyond. ?We want to know how common Earth-like planets are. The problem with answering that question is that if you don’t know how Earth-like planets are formed – if you don’t understand their connection with astrophysical environments – then all you can do is speculate,? Hester said.

?We think that we’re starting to see a very specific causal connection between astrophysical environments and the things that have to be in place to make a planet like ours.?

Original Source: ASU News Release

Posted on by Fraser Cain

NASA Loans Out Columbia Debris

Image credit: CAIB
The first pieces of Space Shuttle Columbia debris, loaned to a non-governmental agency for testing and research, are on their way from NASA’s Kennedy Space Center (KSC), Fla., to The Aerospace Corporation in El Segundo, Calif.

The Aerospace Corporation requested and will receive graphite/epoxy honeycomb skins from an Orbital Maneuvering System pod, Main Propulsion System Helium tanks, a Reaction Control System Helium tank and a Power Reactant Storage Distribution system tank. The company will use the parts to study re-entry effects on composite materials. NASA notified the Columbia crew’s families about the loan before releasing the items for study.

Earlier this year, Dr. Gary Steckel, senior scientist in the Materials Science Department in the Space Materials Laboratory at The Aerospace Corporation, viewed the items. “We believe these items are representative of the structural composite materials flown on Columbia. They will enable us to successfully meet our objective of calibrating analytical models for predicting reentry behavior of composite structures,” Steckel said.

Researchers believe the testing will show how materials are expected to respond to various heating and loads’ environments. The findings will help calibrate tools and models used to predict hazards to people and property from reentering hardware. The Aerospace Corporation will have the debris for one year to perform analyses to estimate maximum temperatures during reentry based upon the geometry and mass of the recovered composite.

“NASA’s mission includes the development of technologies that improve the safety and reliability of access to space,” said NASA’s Deputy Administrator Fred Gregory. “By allowing the scientific community to study Columbia debris, researchers will have the opportunity to gain unprecedented knowledge about the effects of reentry.”

The request from The Aerospace Corporation was one of several “Request for Information” applications NASA received to study Columbia debris. The eight pieces of hardware were inventoried inside the KSC Vehicle Assembly Building, where Columbia’s debris is stored and prepared for shipment.

“The idea of studying pieces of Columbia came to me in the debris hangar soon after the accident,” said Shuttle Launch Director Mike Leinbach. “It was clear to me we could learn a lot from it, and that we shouldn’t bury the debris as we did with Challenger’s.”

“To see the plan come together is personally rewarding,” Leinbach said. “I hope the technical community will learn as much as possible and put that knowledge to use to improve spacecraft and flight crew system designs in the future,” he said.

For information about NASA and return to flight efforts on the Internet, visit:
http://www.nasa.gov/returntoflight

For information about The Aerospace Corporation on the Internet, visit:
http://www.aero.org/home.html

Original Source: NASA News Release

Posted on by Fraser Cain

Cosmic Hurricane in Starburst Galaxy

Image credit: U WISC
Combining images from orbiting and ground-based telescopes, an international team of astronomers has located the eye of a cosmic hurricane: the source of the 1 million mile-per-hour winds that shower intergalactic space from the galaxy M82.

Situated 10 million light years from our own galaxy, the Milky Way, M82 is one of the most studied objects in the sky. Known as a starburst galaxy for the intense, bright clusters of young stars at its heart, M82 is also characterized by massive jets of hot gas — tens of thousands of light years long — that blast into intergalactic space perpendicular to the starry plane of the galaxy.

Using images combined from the Hubble Space Telescope (HST) and the WIYN Telescope on Kitt Peak, Ariz., a team of astronomers from University College London and the University of Wisconsin-Madison has traced the origin of the galaxy’s “superwind” into the starburst heart of M82. The work shows that the wind is not a single entity, but is made up of multiple gas streams that expand at different rates to form a “cosmic shower” of hot gas expelled from the starburst.

The galaxy’s mighty winds, the astronomers say, were sparked by a near-miss collision with the neighboring giant spiral galaxy M81. That close encounter, according to University College London astronomer Linda Smith, set off an explosive burst of star formation.

“M82 shows intense star formation packed into dense clusters,” says Smith. “This powers plumes of hot gas that extend for tens of thousands of light years above and below the disk of the galaxy. The jets of gas from this pulsating cosmic shower are traveling at more than a million miles an hour into intergalactic space.”

The emphasis of the new work, according to UW-Madison astronomer Jay Gallagher, was on the powerful high-temperature winds of M82 and using the Hubble and WIYN observations in combination to view the galaxy in a new way. “The Hubble and the WIYN data give us a new overall view of the M82 superwind stretching from deep within the starburst into intergalactic space.”

The challenge of the new observations lay in visualizing data covering enormous distances and a huge range in brightness, says Mark Westmoquette, a graduate student at University College London.

“We solved this by overlaying the sharp images from Hubble that cover the inner galaxy, where resolving key details is critical, on top of WIYN data that show the extended wind,” Westmoquette explains. “This approach allowed us to connect inner and outer features with specific sites of star formation.”

Westmoquette likened the exercise to tracing widely dispersed plumes of industrial smoke back to the smokestack from which it originated.

“Just as in the terrestrial case, understanding the flow of chemically enriched matter from galaxies into diffuse intergalactic space requires maps extending from the source to where the plume is lost,” Westmoquette says. “It is a challenge for astronomers.”

In addition to NASA’s Hubble Space Telescope, data for the group’s observations were obtained from the 3.5-meter WIYN Telescope at the Kitt Peak National Observatory in Arizona. The observatory is supported by the National Science Foundation and a consortium of American universities, including UW-Madison.

Original Source: UW-Madison

Posted on by Fraser Cain

Closest Asteroid to the Sun Found

Image credit: NASA/JPL
The ongoing search for near-Earth asteroids at Lowell Observatory has yielded another interesting object. Designated 2004 JG6, this asteroid was found in the course of LONEOS (the Lowell Observatory Near-Earth Object Search) on the evening of May 10 by observer Brian Skiff.

“I immediately noticed the unusual motion,” said Skiff, “so it was certain that it was of more than ordinary interest.” He quickly reported it to the Minor Planet Center (MPC) in Cambridge MA, which acts as an international clearinghouse for asteroid and comet discoveries. The MPC then posted it on a Web page for verification by astronomers worldwide. It happened that all the initial follow up observations, however, were obtained by amateur and professional observers in the Southwest US. The additional sky positions measured in the ensuing few days allowed an orbit to be calculated.

The official discovery announcement and preliminary orbit were published by the MPC on May 13. This showed that the object was located between Earth and Venus (presently the very bright “evening star” in the western sky). In addition, 2004 JG6 goes around the Sun in just six months, making it the asteroid with the shortest known orbital period. Ordinary asteroids are located between the orbits of Mars and Jupiter, roughly two to four times farther from the Sun than Earth, taking several years to go around the Sun.

Instead, 2004 JG6 orbits entirely within Earth’s orbit, only the second object so far found to do so. “What makes this asteroid unique is that, on average, it is the second closest solar system object orbiting the Sun,” said Edward Bowell, LONEOS Director. Only planet Mercury orbits closer to the Sun.

As shown in the included diagram, JG6 crosses the orbits of Venus and Mercury, passing less than 30 million miles from the Sun every six months. The approximate average orbital speed of this asteroid is more than 30 km/sec, or 67,000 miles per hour. Depending on their locations, the asteroid may pass as close as 3.5 million miles from Earth and about 2 million miles from planet Mercury. In the coming weeks 2004 JG6 will pass between Earth and the Sun, just inside Earth’s orbit. It will move through the constellations Cancer and Canis Minor low in the western sky at dusk. Because of the near-exact six-month period, the asteroid should be observable again in nearly the same spot in the sky next May, having gone around the Sun twice while Earth will have made only one circuit.

From present estimates, 2004 JG6 is probably between 500 meters and 1 km in diameter. Despite its proximity, the object poses no danger of colliding with Earth.

Asteroids with orbits entirely within the Earth?s orbit have been informally called “Apoheles,” from the Hawaiian word for orbit. Apohele also has Greek roots: “apo” for outside, and “heli” for Sun. Objects orbiting entirely within Earth?s orbit are thought by dynamicist William F. Bottke of Southwest Research Institute and colleagues to comprise just two percent of the total near-Earth object population, making them rare as well as difficult to discover. This is because they stay in the daylight sky almost all of the time. There may exist about 50 Apoheles of comparable size to or larger than 2004 JG6, but many of them are certain to be unobservable from the ground.

The first asteroid found entirely inside Earth?s orbit was 2003 CP20, found just over a year ago by the NASA-funded Lincoln Laboratory Near-Earth Asteroid Research project, which observes near Socorro, New Mexico. Although larger than 2004 JG6, 2003 CP20 is a little more distant from the Sun.

LONEOS is one of five programs funded by NASA to search for asteroids and comets that may approach our planet closely. The NASA program?s current goal is to discover 90 percent of near-Earth asteroids larger than 1 km in diameter by 2008. There are thought to be about 1,100 such asteroids.

Original Source: Lowell Observatory News Release

Posted on by Fraser Cain

Asteroids Change Colour With Age

Image credit: NASA
In an article published today in the journal Nature, a team led by Robert Jedicke of the University of Hawaii?s Institute for Astronomy provides convincing evidence that asteroids change color as they age.

David Nesvorny, a team member from the Southwest Research Institute in Boulder, CO, used a variety of methods to estimate asteroid ages that range from 6 million up to 3 billion years. Accurate color measurements for over 100,000 asteroids were obtained by the Sloan Digital Sky Survey (SDSS), and catalogued by team members Zeljko Ivezic from the University of Washington and Mario Juric from Princeton University.

Robert Whiteley, a team member from the USAF Space and Missile Systems Center in Los Angeles, points out that ?the age-color correlation we found explains a long-standing discrepancy between the colors of the most numerous meteorites known as ordinary chondrites (OC) and their presumed asteroid progenitors.? Meteorites are chips of asteroids and comets that have fallen to Earth?s surface.

According to Jedicke, ?If you were given a piece of rock from the Grand Canyon, you might expect that it would be red, like the colorful pictures in travel magazines. You?d be forgiven for questioning its origin if the rock had a bluish color. But if you were then told that the rocks turn from blue to Grand Canyon red because of the effects of weather, then everything might make sense. Your gift is simply a fresh piece of exposed rock, whereas the pictures you?ve seen show weathered cliff faces millions of years old.?

Nesvorny explains that this is similar to the situation experienced by asteroid astronomers. ?The meteorites are gifts of the solar system to scientists on Earth?pieces of asteroids delivered to their own backyard. The mystery is that the OC meteorites have a bluish color relative to the reddish color of the asteroids from which they were supposedly released.? Jedicke asks, ?How could they possibly be related??

About thirty years ago, a ?space weathering? effect was proposed to explain the color change. Meteorites, whose surface is affected by their fall through Earth?s atmosphere, are usually studied in laboratories by observing their freshly cut and exposed interiors. Billions of years of exposure of the same material on the surface of an asteroid to solar and cosmic radiation and the heating effect of impacts of tiny asteroids might alter the surface color of asteroids in exactly the manner required to match the color of asteroids.

Jedicke said that they found that ?asteroids get more red with time in exactly the right manner and at the right rate to explain the mystery of the color difference between them and OC meteorites.? He added, ?Even though we have found a link between the two types of objects, we still don?t know what causes space weathering.?

Once these researchers refine their analysis by obtaining more colors of the youngest-known asteroid surfaces, it will be possible to determine the age of any asteroid from its surface color. They are currently searching for a space weathering effect on other types of asteroids in the solar system.

The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.

Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS Web site is http://www.sdss.org/.

The SDSS is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The Johns Hopkins University, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, University of Pittsburgh, Princeton University, the United States Naval Observatory, and the University of Washington.

Original Source: University of Hawaii News Release

Posted on by Fraser Cain

Japanese Spacecraft Images Earth and Moon on Flyby

Image credit: JAXA
The Space Engineering Spacecraft “Hayabusa” (MUSES-C) launched on May 9, 2003, by the Japan Aerospace Exploration Agency (JAXA) has been flying smoothly in a heliocentric orbit for about a year using its ion engines.
On May 19, Hayabusa came close to the Earth, and successfully carried out an earth swing-by to place it in a new elliptical orbit toward the asteroid “ITOKAWA”.

The earth swing-by is a technique to significantly change direction of an orbit and/or speed by using the Earth’s gravity without consuming onboard propellant. Hayabusa came closest to the Earth at 3:22 p.m. on May 19 (Japan Standard Time) at an altitude of approximately 3700 km.

The combination of acceleration by the ion engines and the earth swing-by performed this time was the first technological verification in the world, both in the sense of plot and implementation.
After its precise orbit is determined in a week, Hayabusa will restart its ion engines to fly toward “ITOKAWA”.
Hayabusa acquired earth images using its onboard optical navigation camera (which is for detecting a relative position to an asteroid and for scientific observations) as it neared the Earth. You can find these images at the following websites:

Institute of Space and Astronautical Science (ISAS)
http://www.isas.jaxa.jp/e/index.shtml

Original Source: JAXA News Release

Posted on by Fraser Cain

Atlas II Launches AMC-11 Satellite

Image credit: ILS
International Launch Services (ILS) marked another successful mission tonight, after its Atlas IIAS rocket placed the AMC-11 satellite into orbit for SES AMERICOM.

Both the rocket and the satellite were built by Lockheed Martin Corp. (NYSE:LMT), which is also a partner in the ILS joint venture. This was the fifth launch for ILS in 2004, four of which have been on Atlas rockets. This also was the 72nd consecutive successful launch for the Atlas vehicle family.

The Atlas IIAS rocket lifted of from Cape Canaveral?s Launch Complex 36B at 6:22 p.m. EDT (2222 GMT). The satellite, an A2100 model, was injected into a transfer orbit 28 minutes later. The AMC-11 spacecraft is a twin to AMC-10, launched in February, and together they form SES AMERICOM?s premier cable neighborhood and the platform for its HD-PRIME service.

?We?re proud to deliver another satellite on target for SES AMERICOM,? said ILS President Mark Albrecht. ?We look forward to the same success with our two Proton launches this summer with WORLDSAT 2 and AMC-15, and the AMC-16 mission scheduled for an Atlas V at the end of this year. You could say SES AMERICOM is an ILS Frequent Flyer.?

Albrecht noted the long-standing relationship shared by ILS, SES AMERICOM and its parent company, SES GLOBAL. To date ILS has launched 16 satellites for companies affiliated with SES GLOBAL, including seven for the SES AMERICOM fleet. Last month, the companies announced that three additional satellites for SES AMERICOM and SES ASTRA will be launched on ILS vehicles.

Dean Olmstead, president and CEO of SES AMERICOM, said: ?We have great confidence in ILS, as evidenced by our recent experience with the Atlas IIAS and Proton launch vehicles. We are optimistic that the two Proton launches scheduled for August and October, as well as our first Atlas V launch in December, will be just as flawless as tonight?s AMC-11 Atlas IIAS launch.?

ILS has established itself as the indisputable leader of launch services worldwide and offers the industry’s two best launch systems: Atlas and Proton. With a remarkable launch rate of 63 missions during the past three years, the Atlas and Proton launch vehicles have consistently demonstrated the reliability and flexibility that have made them the vehicles of choice. Further demonstrating ILS as the industry leader, ILS has signed more new contracts than its competitors combined over the same three-year period. By any measure, ILS is truly the global leader.

ILS is a joint venture of Lockheed Martin and Russian rocket builder Khrunichev State Research and Production Space Center. ILS markets and manages the missions on the Atlas rocket in the United States and on the Proton rocket at the Baikonur Cosmodrome, Kazakhstan. ILS was formed in 1995, and is based in McLean, Va., a suburb of Washington, D.C.

Original Source: ILS News Release

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Cassini Gets Another Look at Titan

Image credit: NASA/JPL/Space Science
Cassini continues its ground-breaking observations of Saturn’s mysterious moon Titan, stealing another early peek at its haze-enshrouded surface.

The spacecraft was 29.3 million kilometers (18.2 million miles) from Titan on May 5, 2004 when the image on the left was taken through one of the narrow angle camera’s spectral filters (centered at 938 nanometers) specifically designed to penetrate the moon’s thick atmosphere. The image scale is 176 kilometers (109 miles) per pixel, an improvement in resolution of 30% over the images released on May 6. Cassini’s view of Titan now surpasses Earth-based observations in its ability to show detail.

The image has been magnified 10 times using a procedure which smoothly interpolates between pixels to create intermediate pixel values, and has been enhanced in contrast to bring out details. The mottled pattern is an artifact of the processing. The larger scale brightness variations are real. No further processing to remove the effects of the overlying atmosphere has been performed.

The superimposed coordinate system grid in the accompanying image on the right illustrates the geographical regions of the moon that are illuminated and visible, as well as the orientation of Titan — north is up and rotated 25 degrees to the left. The yellow curve marks the position of the boundary between day and night on Titan.

This image shows about one quarter of Titan’s surface, from 180 to 250 degrees West longitude, and overlaps part of the surface shown in the previous Cassini image release (PIA 05390). (That release also included a map of relative surface brightness variations on Titan as measured from images taken with the Hubble Space Telescope.) The dark northwest-southeast trending southern hemisphere feature extending from 210 degrees to 250 degrees West longitude, and the bright region to the east (right) and southeast of it at -50 degrees latitude and 180 to 230 degrees West longitude on the Hubble map, are visible again in today’s release.

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, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Original Source: CICLOPS News Release

Posted on by Fraser Cain

Second Interim Return to Flight Report Released

Image credit: NASA
2004-0519shuttle-sm.jpg view insert

Image credit: NASA
There have been several significant changes in NASA?s Space Shuttle return to flight effort since the last plenary meeting of the Return to Flight Task Group (RTF TG) in December. First, and most immediately, the schedule for the next launch was moved from September 2004 to March-April 2005. See Figure 1 below. This schedule change was prompted by three developments:

1. additional testing of the susceptibility of the Thermal Protection System (TPS), especially the Reinforced Carbon-Carbon, coupled with advanced analysis of the airflows around the Orbiter, External Tank (ET) and Solid Rocket Boosters indicated that the foam on a larger area of the ET should be stripped and reapplied;

2. some rudder speed brake actuators were discovered to have been incorrectly assembled during the original assembly over 20 years ago. Further, the gears in the actuators have generally suffered some damage with use and time. Therefore, all the actuators are being replaced or refurbished; and

3. design and building of a new camera/laser boom that would be used by the Space Shuttle?s robotic arm to help inspect for possible damage while in orbit.

This change in schedule means that NASA will have additional time to implement the Columbia Accident Investigation Board (CAIB) return to flight recommendations before return to flight. In many cases this change also allows expected plans to be at least partially implemented. For example, the CAIB called for a detailed plan to, among other things, establish an Independent Technical Engineering Authority?it is expected those plans will now be implemented, at least for the Office of Space Flight, before next year.

The expanded time before the next launch also allows NASA additional time to select and perfect methods of, for example, inspecting the TPS for damage. Since the loss of Columbia, NASA has been engaged in a wide-ranging search for corrective and preventive measures of all types. In some cases, the time is approaching when decisions must be made as to the most promising alternatives and resources focused on this smaller set of possibilities?the garden must be thinned. In this sense, the additional time until launch can be seductive and leadership will need to be exercised to sort the many options under consideration.

The second major change since December is the announcement of President Bush?s initiative, or vision, for the future of human space flight. The President proposed to utilize the Space Shuttle to finish the International Space Station (ISS) and then retire the Shuttle. In its place would be continued reliance on international partners to service the ISS as well as the possibility of private sector development of launch vehicles. During the next decade, NASA would also begin to develop the capability to return astronauts to the moon, establish a presence, and move on to explore Mars within the next 20 years.

While the President?s vision has obvious implications for the long-run use of the Shuttle, its effects on the return to flight efforts have not been fully examined. However, no matter how long the Shuttle is used in the future, it must first be safely returned to flight. Therefore, except for potential competition for human resources, the new program should have minimal impact on the actual return to flight activities and the implementation of CAIB recommendations. Third, the Task Group determined that the contingency of utilizing the ISS as a shelter for Shuttle Crew Contingency Support in the event of potentially catastrophic damage on the next flight, is becoming increasingly important in NASA?s decision making for return to flight. Therefore, the Task Group formally notified NASA of its intent to assess this capability much as if it were a CAIB recommendation.

Finally, the Task Group instituted a ?sub-panel? to examine the implications of the increased flow of data resulting from many of the CAIB recommendations and other return to flight initiatives.

The Task Group is encouraged by NASA?s progress since its last plenary in December. Throughout the organization, the people of NASA are engaged and dedicated to correcting the deficiencies that led to the demise of Columbia.

The RTF TG is conditionally closing out three CAIB recommendations. ?Closing out? a recommendation means that NASA has responded adequately to a specific CAIB return to flight recommendation. ?Conditionally? means that the close out is dependent on the delivery of final information and the assurance of NASA that it will keep the RTF TG up-to-date on any new developments pertaining to those recommendations. The three recommendations being conditionally closed out with this second interim report are:

3.3-1: Reinforced Carbon-Carbon Non-Destructive Inspection;
4.2-3: Closeout Inspection; and
6.3-2: NASA/National Imagery and Mapping Agency Memorandum of Agreement.

The Task Group will continue to monitor the implementation of these recommendations and NASA has agreed to notify the Task Group if there is any material change in status.

There has been substantial progress on virtually all of the 12 remaining return to flight recommendations. It is anticipated that several more recommendations will be substantially met by the time of the next RTF TG plenary in the summer.

One universal concern of the Task Group is the personnel requirements to meet the CAIB recommendations and return to flight. The various new organizations, from the NASA Engineering and Safety Center, to the Independent Technical Authority, to the Space Shuttle System Engineering and Integration Office all require talented staff drawn largely from the current NASA and contractor pool. At some point, the ability of the Space Shuttle Program to carry out its mission may be hampered by personnel shortages.

The most important work remains to be efforts to eliminate critical ascent debris. If it could be guaranteed that no critical debris would come from the ET, the immediate cause of the loss of Columbia would be rectified. But such a guarantee is impossible short of extensive testing in flight. Analytical and testing techniques will allow a level of comfort before launch and advances in Non-Destructive Inspection techniques may add to confidence. However, statistically significant results verifying ET debris conditions may not be accomplished even by the end of the Shuttle Program.

As such, on-orbit inspection and repair remain necessary to reduce the risk to future flights. Should one or both of these capabilities not be fully developed by the anticipated date of return to flight, the ability for the crew to await a rescue mission at the ISS will become an important consideration for the next launch.

Original Source: Stafford-Covey Second Interim Report (PDF)