Posted on by Mark Mortimer

Book Review: The Living Universe

Astrobiology is the study of life in the universe. It broadly encompasses many fields but purely for its own purposes. Early astrobiology (not that long ago) was, “a jumble of names with a variety of backgrounds and motivations and no central brain”. Its principal goal, to understand the inception of life, gave rise to many fundamental questions. What is life? How can or will we detect life on other worlds? How did life arise on Earth? What does life need to sustain itself? The questions were many and most still have no clear answer. As we read in this book, NASA had a strong influence in astrobiology in its early days and almost single handedly is keeping it going today.

Not all of the investigations related to astrobiology focussed directly on these lofty queries. For instance, space travel began and gave rise to the possibility of cross-planet contamination. Earth probes landing on foreign bodies (i.e. Viking) or especially when returning from foreign bodies (i.e. Apollo), shouldn’t transfer any harmful life forms. Other foretelling work included Stanley Miler’s experiment that simulated early Earth conditions and resulted in the formation of amino acids. Sidney Fox and his spherical proteinoids or Tom Cech and his RNA World thought they had tagged the beginnings of life in their own way though, not all agree. James Lovelock’s proposal, called Gaia, credited living things with having a dramatic effect on the atmospheric conditions on our planet. The early days were indeed a jumble, often supported by short term NASA contracts and almost always directed to space concepts. Nevertheless, a certain cohesion sprang up, together with the first moniker, exobiology.

Today’s investigations, well documented in the book, identify researchers and provide details relevant to the context of the day. The spectre of a hunt for little green men shadowed the creation of the SETI program and forced its evolution to an independent organization. The asteroid found in the Antarctic was blasted off from Mars billions of years ago and may have traces of life, but shapes tens of nanometres across leave a lot to the imagination. Nevertheless this finding may have assured the Viking and follow on programs that headed to Mars. The hunt for planets, difficult and error prone in the beginning, is now progressing rapidly, with indications that planets frequently occur. Again, throughout, NASA is shown to have a significant presence in these investigations, often supporting the inception stage and sponsoring many workshops and principal investigators. Also a name change happened as exobiology became astrobiology.

The destination of astrobiology is perhaps the most telling. A simple equation says it all. This equation known as the Drake equation, estimates the number of other technological civilizations in the galaxy. As long as this equation results with a value of one or greater, then there is at least one other life form to whom we can communicate. Obviously, if true, this could require a big change in some religions as well as some serious societal circumspections. But until we have the evidence, first contact will remain in the realm of science fiction. Reading between the lines, it appears that NASA is contemplating this question and considering options!

Our living universe is a fascinating subject with lofty goals. Dick and Strick do the history of the field justice by accumulating a description of so many of the activities, projects and workshops that relate to this topic. Sometimes the reading gets a bit dry. Typical passage are, ‘person x of department y at site z on date t did something’. Hundreds of names flow by, as well as contract descriptions, amounts, budgetary issues, personalities and the like. The style is more reminiscent of a memorial tomb than a Carl Sagan novel. Don’t be surprised by this as the funding for the book came from NASA. This does result in an apparent biassed result. For example, the first section of the book includes efforts from around the globe, while the remainder centres almost exclusively on NASA funded activities. Sometimes I got the feeling that this book was just a tool to justify NASA expenditures, which is a shame, as the subject is so interesting, and NASA has made a tremendous contribution. On the whole though, the book is well laid out, has only a few references to techno-speak and successfully covers a lot of information.

Hundreds of great scientists have contributed to astrobiology. This hunt for the understanding of life might be rationalized as the pursuit of knowledge for its own sake, or as a good preparation for contacting other worldly life. Either way, Steven Dick and James Strick in their book, The Living Universe – NASA and the development of Astrobiology, show the progress of these scientists and researchers and give credit to NASA’s support during the build up and implementation of this new research field.

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

Review by Mark Mortimer

Posted on by Fraser Cain

The Winter Solstice Approaches

Image credit: NASA
To understand the Winter Solstice (and by contrast the Summer Solstice) we must first understand a fundamental fact about the earth. Earth?s axis of rotation is tilted approximately 23.5? from vertical. This means that as earth orbits the sun, it points first one hemisphere, then the other toward the sun. This tilt causes sunlight to strike the surface of earth at different angles at different times of year. In the summer, the sun is high overhead for the Northern hemisphere and the heat energy is concentrated over a smaller area. In the winter, when the angle of the sun is low, the energy covers a much larger area and therefore heats less efficiently.

Imagine pointing a flashlight directly at a piece of paper. It’ll create a bright circle of light concentrated in an area. Now tilt the flashlight so that it’s hitting the paper on an angle. The same amount of light is coming out of the flashlight, but it’s spread out over a much larger area of paper. It’s this changing of our angle towards the Sun that gives us seasons.

The season we call ?winter? begins on the Winter Solstice. The word Solstice means ?sun still?. But to understand the significance of the Winter Solstice, we must first go back in time to the Summer Solstice, or first day of summer. Starting on June 21st, the sun gradually loses altitude in the sky as seen at noon. By September 22nd, the sun?s noon time altitude is significantly lower in the sky. The process continues until December 21st. Around this date, the sun seems to hold its position in the sky and then slowly begins to climb northward again; hence the term ?sun still.? To ancient peoples, the Solstice was a significant point in the year.

Because ancient peoples knew nothing of the earth?s tilt, the southward march of the sun was a troubling time. There was fear that one day the sun might continue moving south until was lost entirely. Many cultures conducted rituals to encourage the sun to move north again and when it did there were great celebrations. These celebrations, regardless of culture, all had a common theme that of rekindled light.

Not surprising then that many of the traditions and customs of ancient Solstice celebrations have survived to the present day. Although we know that the sun will begin moving north without any encouragement from humans, we still use this time of cold and darkness to celebrate the theme of rekindled light. From the Hanukah Menorah, to the Scandinavian Yule log, to the lights of the Christmas tree, during this season we seek to push back the darkness with light. Although the forms have evolved over the centuries, we cans still see the spirit of many of the old ways in our present day Solstice celebrations.

Now here is an interesting question to ponder, if the earth were not tilted and we had no seasons, would we celebrate the holidays in the same way?

Written by Rod Kennedy

Posted on by Fraser Cain

Planetary Systems Seen Forming

Two of NASA’s Great Observatories, the Spitzer Space Telescope and the Hubble Space Telescope, have provided astronomers an unprecedented look at dusty planetary debris around stars the size of our sun.

Spitzer has discovered for the first time dusty discs around mature, sun-like stars known to have planets. Hubble captured the most detailed image ever of a brighter disc circling a much younger sun-like star. The findings offer “snapshots” of the process by which our own solar system evolved, from its dusty and chaotic beginnings to its more settled present-day state.

“Young stars have huge reservoirs of planet-building materials, while older ones have only leftover piles of rubble. Hubble saw the reservoirs and Spitzer, the rubble,” said Dr. Charles Beichman of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif. He is lead author of the Spitzer study. “This demonstrates how the two telescopes complement each other,” he added.

The young star observed by Hubble is 50 to 250 million years old. This is old enough to theoretically have gas planets, but young enough that rocky planets like Earth may still be forming. The six older stars studied by Spitzer average 4 billion years old, nearly the same age as the sun. They are known to have gas planets, and rocky planets may also be present. Prior to the findings, rings of planetary debris, or “debris discs,” around stars the size of the sun had rarely been observed, because they are fainter and more difficult to see than those around more massive stars.

“The new Hubble image gives us the best look so far at reflected light from a disc around a star the mass of the sun,” said Hubble study lead author, Dr. David Ardila of the Johns Hopkins University, Baltimore. “Basically, it shows one of the possible pasts of our own solar system,” he said.

Debris discs around older stars the same size and age as our sun, including those hosting known planets, are even harder to detect. These discs are 10 to 100 times thinner than the ones around young stars. Spitzer’s highly sensitive infrared detectors were able to sense their warm glow for the first time.

“Spitzer has established the first direct link between planets and discs,” Beichman said. “Now, we can study the relationship between the two.” These studies will help future planet-hunting missions, including NASA’s Terrestrial Planet Finder and the Space Interferometry Mission, predict which stars have planets. Finding and studying planets around other stars is a key goal of NASA’s exploration mission.

Rocky planets arise out of large clouds of dust that envelop young stars. Dust particles collide and stick together, until a planet eventually forms. Sometimes the accumulating bodies crash together and shatter. Debris from these collisions collects into giant doughnut-shaped discs, the centers of which may be carved out by orbiting planets. With time, the discs fade and a smaller, stable debris disc, like the comet-filled Kuiper Belt in our own solar system, is all that is left.

The debris disc imaged by Hubble surrounds the sun-like star called HD 107146, located 88 light-years away. John Krist, a JPL astronomer, also used Hubble to capture another disc around a smaller star, a red dwarf called AU Microscopii, located 32 light-years away and only 12 million years old. The Hubble view reveals a gap in the disc, where planets may have swept up dust and cleared a path. The disc around HD 107146 also has an inner gap.

Beichman and his colleagues at JPL and the University of Arizona, Tucson, used Spitzer to scan 26 older sun-like stars with known planets, and found six with Kuiper Belt-like debris discs. The stars range from 50 to 160 light-years away. Their discs are about 100 times fainter than those recently imaged by Hubble, and about 100 times brighter than the debris disc around the sun. These discs are also punctuated by holes at their centers.

Both Hubble images were taken with the advanced camera for surveys. They will be published in the Astronomical Journal and the Astrophysical Journal Letters. The Spitzer observations are from the multiband imaging photometer and will appear in the Astrophysical Journal.

The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

Original Source: Hubble News Release

Posted on by Fraser Cain

Tarantula Nebula in Detail

The Tarantula Nebula is one of the most impressive views in the Southern sky, cf. ESO Press Photos 14a-g/02. Visible to the unaided eye in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way that is located in the direction of the southern constellation Doradus at a distance of about 170,000 light-years, this huge nebula is the prototype of what astronomers refer to as a “Giant HII region”. In this complex of glowing gas and very hot and luminous stars, the gas is mainly composed of protons and electrons, which are kept apart by energetic photons emitted by the stars in this area.

The Tarantula Nebula (also designated 30 Doradus) owes its name to the arrangement of its brightest patches of nebulosity that somewhat resemble the legs of a spider. They extend from a central “body” where a cluster of hot stars (designated “R136”) resides that illuminate the nebula. This name, of the biggest spiders on the Earth, is also very fitting in view of the gigantic proportions of the celestial nebula – it measures nearly 1,000 light years across!

While the central regions of 30 Doradus may be compared to a tarantula, the entangled filaments in the outskirts of this nebula – some of which are seen in PR Photo 34a/04 – could well be likened with its cobweb. They testify to an ongoing history of very vigorous activity and make this spectacular sky region a showcase of dramatic effects caused by the tremendous output of energy from the most massive stars known.

Intricate colours
The marvellous richness of the filament colours is due to the varying conditions in the interstellar gas in this region, cf. PR Photo 34b/04. The red in these images is caused by emission of excited hydrogen atoms, the green shades correspond to emission from oxygen atoms from which two electrons (“doubly-ionized oxygen”) have been “knocked off” by the energetic radiation of hot stars in the R136 cluster, that is located beyond the lower right corner of this photo. The intensity of this emission increases towards R136, explaining the yellowish colour near the edge of the photo.

A blue colour is contributed by singly-ionized atoms of oxygen. Other atoms like nitrogen and sulfur at different levels of ionization also add to the emission of the nebula at specific wavelengths. The observed colours thus probe the physical condition of the emitting gas and the temperature of the star(s) that excite(s) it. The intricate appearance of the filaments is mostly a consequence of turbulence in the interstellar gas, of the magnetic fields, and of the energy input by the massive stars in the neighbourhood.
Supernovae blow interstellar “bubbles”

The large ring-shaped nebula slightly to the lower-left (South-East) of the centre of PR 34a/04 is known as DEM L 299 [1]. Detailed investigations show that it represents an “interstellar bubble” which was “blown” by supernovae explosions, most probably happening millions of years ago, as massive stars near the centre of this structure ended their comparatively short lives in glorious flashes.

A closer inspection shows that another supernova exploded somewhat later near the rim, forming a bright and more compact nebula known as SNR 0543-689 (PR 34c/04). Other supernovae in this general field exploded even more recently, such as the one that created the remnant B0544-6910 (PR 34d/04) only a few tens of thousands of years ago, a blink of an eye by all astronomical standards.

Nebulae with built-in powerhouses
Not all the nebulae seen in this region are caused by supernovae, however. The glow of N 164 [1], a bright, extended red-yellow nebula just below DEM L 299, is mostly due to its own “private” powerhouse, that consists of several massive stars deeply embedded in its interior (PR Photo 34e/04).

The same holds for DEM L 297, the somewhat smaller and fainter nebula to the right of DEM L 299 (PR Photo 34f/04). It is divided into two half-circle formed segments by a dark lane of interstellar dust in front of it. Indeed, within the Tarantula complex many such dark and dusty clouds are seen in silhouette as they obscure bright nebulosity behind them.

Many stellar clusters
The outskirts of the Tarantula Nebula are also rich in stellar clusters. One of them, NGC 2093 [1], cf. PR Photo 34g/04, has relatively few stars and is relatively young, just a few tens of millions of years. It appears that its stars have already excavated a sizeable cavity around them that is now relatively void of gas.

An older and much more compact cluster, NGC 2108, is seen near the bottom of PR Photo 34h/04 and reproduced in full in PR Photo 34a/04. It resembles the globular clusters in our own Galaxy, but it formed much more recently, about 600 million years ago. Still, NGC 2108 is much older than the Tarantula complex and it is quite possible that in its “youth” it was the core of another giant HII region that has since dissolved into interstellar space.

The images for this release were produced by two ESO astronomers who are impressed by this sky region. Nausicaa Delmotte did the observations for her thesis and notes that: “many of the nebulae and clusters seen in these photos would stand out prominently if they were located elsewhere in the sky and not this close to the core of the spectacular Tarantula complex.”. She is echoed by her colleague, Fernando Comeron: “This amazing concentration of clusters, HII regions, supernova remnants, and extremely hot and luminous stars in a single region makes the Tarantula in the LMC a unique celestial object, unrivalled in our own Galaxy and other nearby galaxies!”.
Note

[1]: The designation “DEM L 299” indicates that this object is no. 299 in the list of nebulae in the Large and Small Magellanic Clouds published in 1976 by astronomers R.D.Davies, K.H.Elliott and J.Meaburn. “N” refers to a list of bright nebulae in these galaxies that was compiled in 1956 by K.G.Henize. “NGC” stands for the “New General Catalogue” published in 1888 by J.L.E. Dreyer.

Original Source: ESO News Release

Posted on by Fraser Cain

Streaks Across Dione

A gorgeous Dione poses for Cassini, with shadowed craters and bright, wispy streaks first observed by the Voyager spacecraft 24 years ago. The wispy areas will be imaged at higher resolution in mid-December 2004. Subtle variations in brightness across the surface of this moon are visible here as well. Dione’s diameter is 1,118 kilometers, (695 miles).

The image shows primarily the trailing hemisphere of Dione, which is the side opposite the moon’s direction of motion in its orbit. The image has been rotated so that north is up.

The image was taken in visible light with the Cassini spacecraft narrow angle camera on Oct. 27, 2004, at a distance of about 1.2 million kilometers (746,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 28 degrees. The image scale is 3.5 kilometers (2.2 miles) per pixel.

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 Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

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: NASA/JPL/SSI News Release

Posted on by Fraser Cain

People, Not Robots, Should Upgrade Hubble

To ensure continuation of the extraordinary scientific output of the Hubble Space Telescope and to prepare for its eventual de-orbiting, NASA should send a space shuttle mission, not a robotic one, says a new congressionally requested report from the National Academies’ National Research Council. The agency should consider launching the manned mission as early as possible after the space shuttle is deemed safe to fly again, because some of the telescope’s components could degrade to the point where it would no longer be usable or could not be safely de-orbited, said the committee that wrote the report.

“A shuttle servicing mission is the best option for extending the life of the Hubble telescope and ultimately de-orbiting it safely,” said committee chair Louis J. Lanzerotti, distinguished research professor at the New Jersey Institute of Technology, Newark, and consultant, Bell Laboratories, Lucent Technologies, Murray Hill, N.J. “NASA’s current planned robotic mission is significantly more technologically risky, so a robotic mission should be pursued only for the eventual removal of the Hubble telescope from orbit, not for an attempt to upgrade it. Also, a shuttle mission could be used to place equipment on the telescope to make a robotic de-orbiting mission more feasible.”

The Hubble telescope, which has operated continuously in orbit for the past 14 years, was designed to be serviced regularly by astronauts. Four servicing missions replaced nearly all the key components while increasing the telescope’s capabilities. The fifth and final mission — to replace aging batteries, fine-guidance sensors, gyroscopes, and two scientific instruments — was originally intended to be completed by a shuttle crew as well, but NASA is currently planning an unmanned mission to service the telescope robotically.

The committee’s principal concerns about a robotic mission are the risk of failing to develop it in time and the risk of a mission failure, as well as the possibility that the robot could critically damage the telescope. A robotic mission would face significant challenges in using its grapple system to perform autonomous close-proximity maneuvers and the final capture of the space telescope — activities that have no precedent in the history of the space program and whose chances of success are low, according to the committee.

“Our detailed analyses showed that the proposed robotic mission involves a level of complexity that is inconsistent with the current 39-month development schedule,” said Lanzerotti. “The design of such a mission, as well as the immaturity of the technology involved and the inability to respond to unforeseen failures, make it highly unlikely that NASA will be able to extend the scientific lifetime of the telescope through robotic servicing.”

The committee assessed the safety risks of a shuttle servicing mission by comparing shuttle missions to the International Space Station — to which NASA plans to send 25 to 30 more shuttle flights — and shuttle missions to the Hubble telescope. The differences between the risks faced by the crew of a single shuttle mission to the space station and the risks faced by the crew of a mission to the Hubble telescope are very small, the committee concluded.

Also, a shuttle crew would be able to successfully carry out unforeseen repairs to the Hubble telescope and develop innovative procedures for unexpected challenges in orbit, the report notes. Such contingencies have been successfully addressed on three of the four prior missions to the telescope. A robotic mission, on the other hand, might not be able to repair failures that it is not designed to address, possibly stalling the mission in its early stages.

“With the replacement of aging components and the installation of new science instruments, Hubble is expected to generate as many new discoveries about stars, extra-solar planets, and the far reaches of the universe as it has already produced so far, with images 10 times more sensitive than ever before,” Lanzerotti said.

Original Source: National Academies of Science

Posted on by Fraser Cain

Private Spaceflight Bill Passes

The U.S. Senate gave final congressional approval to the Commercial Space Launch Amendments Act (H.R. 5382) on Wednesday, which will allow private citizens to fly on suborbital launch vehicles at their own risk. Backers of this legislation said that it was necessary to encourage space tourism companies, like Richard Branson’s Virgin Galactic, to risk making flights in the United States. Those opposed to the bill were concerned that regulators would have to stand by until someone actually got hurt before changing the rules.

Posted on by Fraser Cain

Mission to Neptune Under Study

In 30 years, a nuclear-powered space exploration mission to Neptune and its moons may begin to reveal some of our solar system’s most elusive secrets about the formation of its planets — and recently discovered ones that developed around other stars.

This vision of the future is the focus of a 12-month planning study conducted by a diverse team of experts led by Boeing Satellite Systems and funded by NASA. It is one of 15 “Vision Mission” studies intended to develop concepts in the United States’ long-term space exploration plans. Neptune team member and radio scientist Professor Paul Steffes of the Georgia Institute of Technology’s School of Electrical and Computer Engineering calls the mission “the ultimate in deep space exploration.”

NASA has flown extensive missions to Jupiter and Saturn, referred to as the “gas giants” because they are predominantly made up of hydrogen and helium. By 2012, these investigations will have yielded significant information on the chemical and physical properties of these planets. Less is known about Neptune and Uranus — the “ice giants.”

“Because they are farther out, Neptune and Uranus represent something that contains more of the original – to use a ‘Carl Saganism’ – ‘solar stuff’ or the nebula that condensed to form planets,” Steffes said. “Neptune is a rawer planet. It is less influenced by near-sun materials, and it’s had fewer collisions with comets and asteroids. It’s more representative of the primordial solar system than Jupiter or Saturn.”

Also, because Neptune is so cold, its structure is different from Jupiter and Saturn. A mission to investigate the origin and structure of Neptune — expected to launch between 2016 and 2018 and arrive around 2035 — will increase scientists’ understanding of diverse planetary formation in our solar system and in others, Steffes noted.

The mission team is also interested in exploring Neptune’s moons, especially Triton, which planetary scientists believe to be a Kuiper belt object. Such balls of ice are micro planets that can be up to 1,000 kilometers in diameter and are generally found in the outermost regions of our solar system. Based on studies to date, scientists believe Triton was not formed from Neptune materials, like most moons orbiting planets in our solar system. Instead, Triton is likely a Kuiper belt object that was accidentally pulled into Neptune’s orbit.

“Triton was formed way out in space,” Steffes said. “It is not even a close relative of Neptune. It’s an adopted child?. We believe Kuiper belt objects like Triton were key to the development of our solar system, so there’s a lot of interest in visiting Triton.”

Though they face a number of technical challenges — including entry probe design, and telecommunications and scientific instrument development — the Neptune Vision Mission team has developed an initial plan. Team members, including Steffes, have been presenting it this fall at a variety of scientific meetings to encourage feedback from other experts. On Dec. 17, they will present it again at the annual meeting of the American Geophysical Union. Their final recommendations are due to NASA in July 2005.

The plan is based on the availability of nuclear-electric propulsion technology under development in NASA’s Project Prometheus. A traditional chemical rocket would launch the spacecraft out of Earth orbit. Then an electric propulsion system powered by a small nuclear fission reactor – a modified submarine-type technology — would propel the spacecraft to its deep-space target. The propulsion system would generate thrust by expelling electrically charged particles called ions from its engines.

Because of the large scientific payload a nuclear-electric propelled spacecraft can carry and power, the Neptune mission holds great promise for scientific discovery, Steffes said.

The mission will employ electrical and optical sensors aboard the orbiter and three probes for sensing the nature of Neptune’s atmosphere, said Steffes, an expert in remote radio sensing of planetary atmospheres. Specifically, the mission will gather data on Neptune’s atmospheric elemental ratios relative to hydrogen and key isotopic ratios, as well as the planet’s gravity and magnetic fields. It will investigate global atmospheric circulation dynamics, meteorology and chemistry. On Triton, two landers will gather atmospheric and geochemical information near geysers on the surface.

The mission’s three entry probes will be dropped into Neptune’s atmosphere at three different latitudes – the equatorial zone, a mid-latitude and a polar region. Mission designers face the challenge of transmitting data from the probes through Neptune’s radiowave-absorbing atmosphere. Steffes’ lab at Georgia Tech has conducted extensive research and gained a thorough understanding of how to address this problem, he noted.

The mission team is still discussing how deep the probes should be deployed into Neptune’s atmosphere to get meaningful scientific data. “If we pick a low enough frequency of radio signals, we can go down to 500 to 1,000 Earth atmospheres, which is 7,500 pounds of pressure per square inch (PSI),” Steffes explained. “That pressure is similar to what a submarine experiences in the deep ocean.”

However, that depth will probably not be required, according to the mission team’s atmospheric modelers, Steffes said. The probes will be able to obtain most information at only 100 Earth atmospheres, or 1,500 PSI.

Original Source: Georgia Tech News Release

Posted on by Fraser Cain

Saturn’s C Ring

This view of Saturn’s outer C ring shows the extreme variations in brightness, along with the subtle, large-scale wavy variations discovered 24 years ago by NASA’s Voyager spacecraft. The notably dark Maxwell gap (near upper right) contains the bright, narrow and eccentric Maxwell ringlet, a Saturnian analog of the narrow Uranian epsilon ring. The gap also contains another very faint ringlet newly discovered by Cassini.

The image was taken with the Cassini spacecraft narrow angle camera on Oct. 29, 2004, at a distance of 838,000 (521,000 miles) from Saturn. The center of this view shows an area located approximately 81,300 kilometers (50,500 miles) from the planet. The image scale is 4.6 kilometers (2.9 miles) per pixel.

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 Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

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: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Study Negative on Hubble Repair

There has been tremendous controversy ever since NASA announced that they wouldn’t sending astronauts to repair and upgrade the aging Hubble Space Telescope. An independent report delivered to the agency says that even sending a robotic mission to repair the observatory is probably a bad idea – it would be too costly and risky. A robotic mission might take $2 billion or more to develop, might not reach Hubble in time, and probably only has a 50% chance of succeeding – it would be more cost effective to launch a new observatory with the instruments built for Hubble.