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

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)

Japanese Celebrity Will Visit the Space Station

Image credit: Space Adventures
Space Adventures, Ltd., the world’s leading space experiences company, announced today it has begun working with Dentsu, the world’s largest advertising agency, to send a prominent Japanese figure to the International Space Station (ISS) within the next several years.

As part of the agreement with Dentsu, Space Adventures will dedicate one of the four seats the company has available on the Russian Soyuz TMA spacecraft. Space Adventures currently has a contract with the Federal Space Agency of Russia that provides them with the sole rights to transport the next four private space explorers to the ISS. The first of the four seats has already been contracted by American technology entrepreneur, Greg Olsen, Ph.D., who is currently training at the Yuri Gargarin Training Center in Star City, Russia. His expedition is currently planned for April 2005. With two of the four seats committed, Space Adventures has two seats remaining on the Soyuz.

“I welcome the opportunity to work with Dentsu. They are the world’s premier advertising agency and we are delighted to embark on such an exciting opportunity with them,” said Eric Anderson, president and CEO of Space Adventures. “As Dentsu has cultivated unique artistic designs and opportunities for advertising in today’s marketplace, we, at Space Adventures, are using the same enthusiasm and innovative techniques to open the space frontier to private citizens. Together, we will make history by sending the first Japanese private explorer to space.”

About Space Adventures: The world’s leading space flight experiences and space tourism company offers a wide range of programs from Zero-Gravity and Edge of Space flights, cosmonaut training and space flight qualification programs to reservations on future suborbital spacecraft. Headquartered in Arlington, Va., with an office in Moscow, Space Adventures is the only company to have successfully launched private individuals to the ISS. The company’s advisory board comprises Apollo 11 moonwalker Buzz Aldrin, shuttle astronauts Kathy Thornton, Robert (Hoot) Gibson, Charles Walker, Norm Thagard, Sam Durrance and Byron Lichtenberg and Skylab astronaut Owen Garriott.

About Dentsu Inc.: Founded in 1901, Dentsu is the largest advertising agency brand and the fifth largest marketing and communications organization in the world. Based in Tokyo, Dentsu offers national, multinational and global clients the most comprehensive range of advertising and marketing services through its unique “Total Communications Services” approach. Dentsu has pioneered and set global standards for integrated communications, which in latter years have been adopted by a number of major international networks. The group has more than 6,000 clients and 14,245 full-time employees in both Japan and in its offices overseas. Consolidated billings (net sales) for fiscal term 03/04 were recorded at 1,749 billion yen. Dentsu is publicly quoted on the Tokyo Stock Exchange. For more information, please visit www.dentsu.com.

Original Source: Space Adventures News Release

How to Avoid Space Madness

Image credit: Mars Society
Defiance, detachment, disagreement ? harmful emotions in any small group situation, but in Outer Space these feelings are particularly damaging and possibly life endangering.

ANU psychologists are preparing to gather unique insights into the duress of space travel as part of a ?Mars expedition? to be staged in the Australian desert later this year.

The way that small groups of astronauts interact in the extreme, unfamiliar and isolating conditions of space travel will be closely scrutinised by Dr Rachael Eggins, Dr Kate Reynolds and PhD student Mr Phill Krins, from the Psychology Department in the ANU Faculty of Science.

The researchers are set to record the interactions of participants of an expedition into the South Australian outback in August organised by the Mars Society of Australia. This follows on from an initial study of participants in a planetary simulation in the United States last year.

?The rigorous personality testing astronauts undergo in their relatively cosy, comfortable labs can not measure how their personality might change in a confined, socially stifling and unfamiliar space,? Dr Eggins says.

?In everyday life we are very socially dynamic and belong to a number of groups, such as family, work and friends. There are a number of psychological advantages to having such a dynamic social environment, which will be absent when people spend long periods of time in isolation.?

Mr Krins and Dr Steve Dawson, a research psychologist with the Mars Society of Australia, will travel into the desert with the expedition and ask participants ? who try and replicate as closely as possible what it would be like living and working on Mars ? to complete questionnaires designed to monitor social dynamics.

Participants will undergo a daily cortisol (a hormone produced by the body in reaction to stress) measurement test and cognitive testing to gauge stress and performance levels.

Mr Krins will also keep a daily journal to record important social events, such as leadership changes, likely to affect the social dynamics of the expedition.

?One thing we are interested in is the question of whether or not groups are good or bad for your health,? Dr Eggins says. ?We know that in cohesive groups people perform better, work harder and are more cooperative than in loose-knit groups.

?But do cohesive groups make us work too hard and what does that do to our stress levels??

There are also other issues relating to the wrong sort of cohesion in a group, and small sub-groups forming within larger groups.

?There is a danger groups may become too cohesive,? Mr Krins says.

?When this occurs there may be intense pressure for individual crew members to behave in accordance with ?group norms?. For example, if there is a group norm to not report safety breaches, this could put the entire crew in danger.?

Also, past research on groups (whether isolated or not) has shown that it is common for the larger group to splinter into smaller subgroups.

?A number of problems can occur when large groups split off into these smaller groups,? Dr Eggins says. ?Polarisation can lead to infighting and poor decision-making.

?But there are advantages ? subgroups can become an important source of creative new ideas benefiting the larger group. Subgroups are also an important source of identity and pride for people. They then work hard to achieve its goals, improving the mission as a whole.?

With unmanned Mars missions underway and intensifying research interest in the red planet, the ANU researchers believe the human element of space exploration should be taken just as seriously as the technological or scientific. The team?s research will focus on developing guiding principles to avoid problems associated with groups in such stressful circumstances.

?It is important that group differences are managed properly and don?t become a source of conflict or feelings of disenfranchisement,? Dr Eggins says.

?These principles will ensure that individuals maintain commitment to the whole, have avenues for input into decision making and follow leadership guidelines.?

Original Source: ANU News Release

Unmanned Amateur Rocket Reaches Space

A team of amateur rocket builders accomplished a major feat this week; the first privately built rocket to reach the edge of space. The 6.5-metre (21 foot) unmanned rocket blasted off from its Nevada launch pad, and reached a speed of 6500 km/h (4000 m/h) in only 9 seconds. Based on this velocity, the Civilian Space Exploration Team (CSXT) calculated that it would have reached the official edge of space at 100 km (62.5 m). The CSXT team has detected the rocket’s landing telemetry information, but hasn’t been able to locate it on the ground yet.

Chandra Furthers Understanding About Dark Energy

Image credit: Chandra
Dark energy. Does it exist, and what are its properties? Using galaxy-cluster images from NASA’s Chandra X-ray Observatory, astronomers have applied a powerful, new method for detecting and probing dark energy. The results offer intriguing clues about the nature of dark energy and the fate of the Universe. The Marshall Center manages the Chandra program.
Photo: Composite image of the galaxy cluster Abell 2029 (Optical: NOAO/Kitt Peak/J.Uson, D.Dale; X-ray: NASA/CXC/IoA/S.Allen et al.)

Astronomers have detected and probed dark energy by applying a powerful, new method that uses images of galaxy clusters made by NASA’s Chandra X-ray Observatory. The results trace the transition of the expansion of the Universe from a decelerating to an accelerating phase several billion years ago, and give intriguing clues about the nature of dark energy and the fate of the Universe.

“Dark energy is perhaps the biggest mystery in physics,” said Steve Allen of the Institute of Astronomy (IoA) at the University of Cambridge in England, and leader of the study. “As such, it is extremely important to make an independent test of its existence and properties.”

Allen and his colleagues used Chandra to study 26 clusters of galaxies at distances corresponding to light travel times of between one and eight billion years. These data span the time when the Universe slowed from its original expansion, before speeding up again because of the repulsive effect of dark energy.

“We’re directly seeing that the expansion of the Universe is accelerating by measuring the distances to these galaxy clusters,” said Andy Fabian also of the IoA, a co-author on the study. The new Chandra results suggest that the dark energy density does not change quickly with time and may even be constant, consistent with the “cosmological constant” concept first introduced by Albert Einstein. If so, the Universe is expected to continue expanding forever, so that in many billions of years only a tiny fraction of the known galaxies will be observable.

If the dark energy density is constant, more dramatic fates for the Universe would be avoided. These include the “Big Rip,” where dark energy increases until galaxies, stars, planets and eventually atoms are eventually torn apart. The “Big Crunch,” where the Universe eventually collapses on itself, would also be ruled out.

Chandra’s probe of dark energy relies on the unique ability of X-ray observations to detect and study the hot gas in galaxy clusters. From these data, the ratio of the mass of the hot gas and the mass of the dark matter in a cluster can be determined. The observed values of the gas fraction depend on the assumed distance to the cluster, which in turn depends on the curvature of space and the amount of dark energy in the universe.

Because galaxy clusters are so large, they are thought to represent a fair sample of the matter content in the universe. If so, then relative amounts of hot gas and dark matter should be the same for every cluster. Using this assumption, Allen and colleagues adjusted the distance scale to determine which one fit the data best. These distances show that the expansion of the Universe was first decelerating and then began to accelerate about six billion years ago.

Chandra’s observations agree with supernova results including those from the Hubble Space Telescope (HST), which first showed dark energy’s effect on the acceleration of the Universe. Chandra’s results are completely independent of the supernova technique – both in wavelength and the objects observed. Such independent verification is a cornerstone of science. In this case it helps to dispel any remaining doubts that the supernova technique is flawed.

“Our Chandra method has nothing to do with other techniques, so they’re definitely not comparing notes, so to speak,” said Robert Schmidt of University of Potsdam in Germany, another coauthor on the study.

Better limits on the amount of dark energy and how it varies with time are obtained by combining the X-ray results with data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), which used observations of the cosmic microwave background radiation to discover evidence for dark energy in the very early Universe. Using the combined data, Allen and his colleagues found that dark energy makes up about 75% of the Universe, dark matter about 21%, and visible matter about 4%.

Allen and his colleagues stress that the uncertainties in the measurements are such that the data are consistent with dark energy having a constant value. The present Chandra data do, however, allow for the possibility that the dark energy density is increasing with time. More detailed studies with Chandra, HST, WMAP and with the future mission Constellation-X should provide much more precise constraints on dark energy.

“Until we better understand cosmic acceleration and the nature of the dark energy we cannot hope to understand the destiny of the Universe,” said independent commentator Michael Turner, of the University of Chicago.

The team conducting the research also included Harald Ebeling of the University of Hawaii and the late Leon van Speybroeck of the Harvard-Smithsonian Center for Astrophysics. These results will appear in an upcoming issue of the Monthly Notices of the Royal Astronomy Society.

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at:

http://chandra.harvard.edu/
and
http://chandra.nasa.gov/

Original Source: NASA News Release

New Photo of Comet NEAT

Astrophotographer John Chumack sent in this image of Comet Neat which he took last night. He used a Canon 10D digital SLR and 4″ F8 refractor telescope, ISO 400, 9 minute exposure. If you want to see the comet for yourself, just head outside and look to the West. It’s a fuzzy blur that you can just make out with the unaided eye, even in the city. You can make it out much better with a pair of binoculars. Skymaps.com has conveniently put positions of Comet’s NEAT and LINEAR for the month of May in its current sky chart, so head there and grab a free map to help you orient yourself. Get some friends and make an evening of it.

Good luck!

Fraser Cain
Publisher
Universe Today

Book Review: Gorgon

Peter Ward cut his teeth, so to speak, on a more recent mass extinction. This event was the Cretaceous-Tertiary or K/T mass extinction about 65 million years ago that saw the end of the dinosaurs and many of their co-habitants. Fortunately for people, it also paved the way for the dominance of mammals. The quest that drove Peter and other paleontologists was to find the reason for the mass extinction. After extensive investigation of the K/T boundary, the cause was ruled not to be a long, gradual climate change but a brief flash due to an asteroid hitting at Chicxulub in the Yucatan peninsula of Mexico. Peter’s own findings supported the final conclusion but seeing as it was a conclusion, Peter was left without a future target for his personal challenge.

The end of the Permian period was similar to the end of the Cretaceous period as each ended with a mass extinction. However, the Permian period was a more complete extinction and, as it occurred hundreds of millions of years beforehand, there was a lot less material to substantiate either a cause or a process. Peter fortuitously began studying this event. Over the ensuing twenty years, he experienced both political extremes in the pre and post apartheid and environmental extremes as he traversed the back country called the Karoo. He discovered much about the mass extinction and much about himself.

The lands of the Karoo do not give up their secrets easily. Though effectively a desert region, its temperature ranges from below freezing to well above 40 Celsius. Sunstroke and frostbite were equally possible. Ticks were incessant and could in one bite lead to a painful and fateful end. Puff adders and Cape cobras abounded. Clean water didn’t. Restaurants and hotels were few and far between and of limited quality. In spite of the hardships, or perhaps because of them, many every day visions took on a greater grandeur. Night skis were a crystal clear panoply of stars, galaxies and light shows. Rivers had recuperative powers better than any pharmaceutical pill. And, of course, the sighting of a fossil made the rigour of many a hard day melt away. The Karoo had the evidence needed to help explain the Permian boundary extinction but it did so grudgingly.

Being a paleontologists, as is Peter, gives perhaps a somewhat unique perspective of today’s events on Earth. Some claim that the Earth at this moment is experiencing another mass extinction. However, this time it is not due to celestial strikes but through the actions of a singular species, humans. Humanity is causing the loss of species at a rate ten times faster than at any time since the last mass extinction. In addition, with its alteration to the Earth’s environment, especially the atmosphere, many of the indicators for the start of a mass extinction are again present. Further, if a large extinction occurs, then with the human caused reduction in biodiversity, the Earth may again need tens of millions of years to achieve a full set of complex life forms. Peter raises such perspectives and in so doing easily justifies the time and effort spent examining an event hundreds of millions of years old.

This backward look in time is equally exciting for space enthusiasts. NASA itself is funding significant investigations into the Earth’s mass extinctions and the beginnings of life. The definition of life and its constituent matters may seem complete but seeing new life forms at undersea volcanoes or kilometres deep in granite lends credence to the belief that life can exist elsewhere than Earth. Further, the study of mass extinctions can lead to the definition of the processes of evolution as well as ecosystem dependencies. From this, conjecture can be raised about the effects of the loss of species and phyla, as well as the effects of another asteroid striking Earth. Such scenarios easily give NASA greater support to develop lunar bases and space travel.

After reading this book, you will discard any romantic notions you may have had about being a fossil hunter. Peter clearly describes days of sweat, years of poor pay and few occasions of reward. His personal vindications allow a reader to feel the warmth of comradery, the joys of mystery meat on pizza and the satisfaction of contributing to scientific knowledge. As much as this book reinforces a career choice other than a paleontologist, I’m glad there are people like Peter who do this work and are able to write a book for a non-practitioner to enjoy.

Yet, though I’m not a paleontologist, I would have liked a clearer description of the events and surroundings being investigated. There is a flourish that waxes about the vast expanse of life before the Permian mass extinction and the lack thereafter, but there is little detail. Also, reference is made to activities and researchers elsewhere, but these seem more of an add on than part of the narrative. Peter includes more of his feelings than details of his work, which may please or discourage the reader.

The Gorgonopsian was a predator from the Permian period. It became extinct along with about 95 percent of its fellow inhabitants on Earth at the end of this period. Peter Ward, in his book Gorgon, describes his personal challenges and successes in prying the secrets of fossils from the back country of South Africa. In reading this book, you can easily end up wondering about the huge expanse of lives and events that have gone before us, wondering about current and past politics or just wondering about what drives people to do the things they do.

You can also read a review of Ward’s previous book, The Life and Death of Planet Earth here on Universe Today.

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

Review by Mark Mortimer

New Satellite to Assess the Health of the Earth’s Atmosphere

Image credit: NASA/JPL
On June 19, NASA will launch Aura, a next generation Earth- observing satellite. Aura will supply the best information yet about the health of Earth’s atmosphere.

Aura will help scientists understand how atmospheric composition affects and responds to Earth’s changing climate. The satellite will help reveal the processes that connect local and global air quality. It will also track the extent to which Earth’s protective ozone layer is recovering.

Aura will carry four instruments designed to survey different aspects of Earth’s atmosphere. The instruments will provide an unprecedented and complete picture of the composition of the atmosphere. Aura will survey the atmosphere from the troposphere, where mankind lives, through the stratosphere, where the ozone layer resides and protects life on Earth.

Aura’s space-based view of the atmosphere and its chemistry will complete the first series of NASA’s Earth Observing System satellites. The other satellites are Terra, which monitors land; and Aqua, which observes Earth’s water cycle.

“Gaining this global view of Earth will certainly reap new scientific discoveries that will serve as essential stepping stones to our further exploration of the Moon, Mars and beyond, the basis of the Vision for Space Exploration,” NASA Administrator Sean O’Keefe said.

Aura will help answer key scientific questions, including whether the ozone layer is recovering. Aura data may prove useful in determining the effectiveness of international agreements that banned ozone-depleting chemicals like chlorofluorocarbons (CFCs).

Aura will accurately detect global levels of CFCs and their byproducts, chlorine and bromine, which destroy ozone. Aura will also track the sources and processes controlling global and regional air quality. It will help distinguish between natural and human-caused sources of these gases. When ozone exists in the troposphere, it acts as an air pollutant. Tropospheric ozone is linked to high levels of precursors such as nitrogen dioxide, carbon monoxide and volatile hydrocarbons. Aura will help scientists follow the sources of tropospheric ozone and its precursors.

“Aura, the first comprehensive laboratory in space to help us better understand the chemistry and composition of the Earth’s atmosphere, is fundamentally a mission to understand and protect the very air we breathe, ” said NASA Associate Administrator for Earth Science Dr. Ghassem Asrar. “It is also a perfect complement to our other Earth Observing System satellites that, together, will aid our nation and our neighbors by determining the extent, causes, and regional consequences of global change.”

As the composition of Earth’s atmosphere changes, so does its ability to absorb, reflect and retain solar energy. Greenhouse gases, including water vapor, trap heat in the atmosphere. Airborne aerosols from human and natural sources absorb or reflect solar energy based on color, shape, size and substance. The impact of aerosols, tropospheric ozone and upper tropospheric water vapor on Earth’s climate remains largely unquantified. Aura’s ability to monitor these agents will help unravel some of their mystery.

Aura’s four instruments, the High Resolution Dynamics Limb Sounder; the Microwave Limb Sounder; the Ozone Monitoring Instrument; and the Tropospheric Emission Spectrometer will work together to provide measurements in the troposphere and stratosphere to help answer important climate questions.

The High Resolution Dynamics Limb Sounder was built by the United Kingdom and the United States. The Ozone Monitoring Instrument was built by the Netherlands and Finland in collaboration with NASA. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., constructed the Tropospheric Emission Spectromer and Microwave Limb Sounder. NASA’s Goddard Space Flight Center, Greenbelt, Md., manages the Aura mission.

NASA’s Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.

Original Source: NASA News Release

Faking Titan in the Lab

Image credit: UA
While the Cassini spacecraft has been flying toward Saturn, chemists on Earth have been making plastic pollution like that raining through the atmosphere of Saturn’s moon, Titan.

Scientists suspect that organic solids have been falling from Titan’s sky for billions of years and might be compounds that set the stage for the next chemical step toward life. They collaborate in University of Arizona laboratory experiments that will help Cassini scientists interpret Titan data and plan a future mission that would deploy an organic chemistry lab to Titan’s surface.

Chemists in Mark A. Smith’s laboratory at the University of Arizona create compounds like those condensing from Titan’s sky by bombarding an analog of Titan’s atmosphere with electrons. This produces “tholins” ? organic polymers (plastics) found in Titan’s upper nitrogen-methane atmosphere. Titan’s tholins are created by ultraviolet sunlight and electrons streaming out from Saturn’s magnetic field.

Tholins must dissolve to produce amino acids that are the basic building blocks of life. But chemists know that tholins won’t dissolve in Titan’s ethane/methane lakes or oceans.

However, they readily dissolve in water or ammonia. And experiments done 20 years ago show that dissolving tholins in liquid water produces amino acids. So given liquid water, there may be amino acids brewing in Titan’s version of primordial soup.

Oxygen is the other essential for life on Earth. But there is almost no oxygen in Titan?s atmosphere.

Last year, however, Caitlin Griffith, of UA?s Lunar and Planetary Laboratory, discovered water ice on Titan?s surface. (See Titan Reveals a Surface Dominated by Icy Bedrock.) UA planetary scientist Jonathan Lunine and others theorize that when volcanoes erupt on Titan, some of this ice could melt and flow across the landscape. Similar flows could result when comets and asteroids slam into Titan.

Better still, Titan?s water may not immediately freeze because it’s probably laced with enough ammonia (antifreeze) to remain liquid for about 1,000 years, Smith and Lunine noted in a research paper published in last November’s issue of “Astrobiology.”

So although Titan is extremely cold — about 94 degrees kelvin (minus 180 degrees Celsius or minus 300 degrees Fahrenheit) — water may briefly flow across the surface, supplying oxygen and a medium for chemistry, they conclude.

To further understand how all this might work together, Smith’s group is generating tholins in the lab, analyzing their spectroscopic properties, and trying to understand their chemistry.

?We?re trying to learn how the compounds will react with molten water on Titan?s surface, what compounds they?ll make, and, therefore, what we should really be looking for,” Smith explained. “We?re not just looking for atmospheric plastic sitting on the surface, but the result of time and energy input over billions of years.

“We want to know what sorts of molecules have evolved, and whether they’ve evolved along pathways that might provide insights into how biological molecules developed on primordial Earth,? he said.

Mark A. Smith, professor and head of UA’s chemistry department

?Some of what we?ve learned so far in our experiments is that these materials are gross mixtures of incredibly complex molecules,? Smith added. ?Carl Sagan spent the last 10 years of his life studying these compounds in experiments like ours. What we?ve found complements his work. We see the same spectroscopic signatures.”

But Smith’s group also has found that there is a component of these molecules that is very reactive and could easily, within a reasonable time frame, react on the surface of Titan to yield oxygenated compounds.

“And that?s what we?re just starting to unravel now,? Smith said.

?Our work will get much more interesting this fall, in our experiments at the Advanced Light Source of the Lawrence Berkeley Lab,” he added. “We?ll be using a synchrotron to create tholins photochemically, using very energetic photons to break up this Titan gas by vacuum ultraviolet radiation.?

Vacuum ultraviolet radiation hits nitrogen and methane molecules in Titan’s upper atmosphere and blasts them apart. Scientists don’t know if this produces the same kinds of polymers that are formed from an electrical discharge.

?When you can crack nitrogen and methane molecules with light, you might get polymers similar to those formed when an electrical discharge cracks them apart,” Smith said. “Or you may get different polymers. The chemistry is quite complex, and we just don’t know the answers to so many of the simplest questions. But that’s one of the reasons we’ll conduct the experiments at Berkeley.?

The work going on in Smith’s lab is important to scientists on NASA’s Cassini Mission and possible follow-up missions to Saturn. The Cassini orbiter was launched in 1997 and is to launch a probe into Titan’s atmosphere in December. This Huygens probe will float to Titan’s surface next January.

?Titan?s thick orange aerosol haze layer is basically a bunch of organic plastics ? polymers of carbon, hydrogen and nitrogen,” said Smith, head of UA’s chemistry department. “The particulates eventually settle on Titan?s surface, where they produce the organic feedstock for any organic chemistry going on.”

Cassini’s Huygens probe will be the first instrument to actually sample this aerosol. It will give scientists some rudimentary chemical information on this material. But the probe won’t tell them much about organic chemistry at Titan’s surface.

A follow-up mission to Titan that includes a robotic organic chemistry laboratory will give scientists a much more detailed look at the surface. The experiment is being designed by Lunine and Smith in collaboration with researchers from Caltech and NASA’s Jet Propulsion Laboratory.

Lunine leads NASA?s Astrobiology Institute focus group on Titan and is one of three interdisciplinary Cassini mission scientists for the Huygens probe.

?We don?t really know how life formed on the Earth, or on whatever planet it formed,? Lunine said. ?There are no traces left of how it happened on Earth, because all of Earth?s organic molecules have been processed biochemically by now. Titan is our best chance to study organic chemistry in a planetary environment that has remained lifeless over billions of years.?

Original Source: UA News Release