On Saturn’s Darkside

Saturn’s splendid rings made visible by sunlight. Image credit: NASA/JPL/SSI. Click to enlarge
This view shows the unlit side of Saturn’s splendid rings made visible by sunlight filtering through the rings from the lit side. Light from the illuminated side of the rings brightens the night side of the planet’s southern hemisphere with “ringshine” (seen here at lower right). The feeble glow from transmitted light dimly illuminates the planet’s northern half.
Saturn’s shadow stretches across the rings toward lower left.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 8, 2005, at a distance of approximately 477,000 kilometers (296,000 miles) from Saturn. The image scale is 25 kilometers (15 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 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 . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Space Telescope Could Unfold in Space

Collimation testbed of the Dobson telescope. Image credit: Tom Segert. Click to enlarge
A novel suitcase-sized telescope could revolutionise the way we see the Earth and other planets. ESA has supported the work of a group of students in developing the Dobson Space Telescope, being tested this month aboard ESA’s parabolic flight campaign aircraft.

This experimental prototype launches in a compact configuration and then unfolds to provide a cost-effective space telescope. It could lead to fleets of low-cost telescopes, bigger than the Hubble Space Telescope.
Large payloads are difficult to put into space because they are usually heavy and expensive to launch. Now a revolutionary design of unfolding telescope, inspired by telescopes used by amateur astronomers, is ready to enter a phase of detailed testing. If successful, it could dramatically reduce the cost of placing telescopes in space.

The telescope is a project of the Department of Astronautics at the Technische Universit?t Berlin, Germany. “We called our project the Dobson Space Telescope because we borrowed the idea from the Dobsonian telescopes used by amateur astronomers,” says project manager Tom Segert, who has recently completed his degree at TU Berlin. Dobsonian telescopes are often comprised of two mirrors, held the correct distance apart by long poles. They can be dismantled and transported by car to a good observing site, where there are reassembled with nothing more complicated than a screwdriver.

In space, however, a screwdriver is useless unless you have an astronaut to turn it and so Segert plans to use a motor to unfold his telescope. Working on a shoestring budget, his first prototype used inflatable bicycle tyres to push the mirrors into position. When this proved incapable of aligning the telescope optics, Segert turned to metal truss rods and micromechanics to unfold everything into its correct place.

Using a grant from ESA’s General Studies Programme, Segert and other TU Berlin students have written a full technical report and built a prototype for testing in this month aboard ESA’s parabolic flight campaign aircraft. As the aircraft flies special manoeuvres, the prototype will experience periods of free-fall that mimic the conditions in space. During this time, Segert will test the telescope?s ability to unfold. Eventually, Segert hopes for a demonstration mission in space.

Currently, space-based observations account for just one tenth of the commercial Earth observation market. The rest is supplied by aeroplane reconnaissance, which is much cheaper. Space observations cost 20 Euros per kilometre whereas aeroplane data is twenty times cheaper. Segert believes that cost-effective Earth observation microsatellites, based on his telescope design, will allow all users access to space images.

There is also nothing to stop a Dobson Space Telescope from turning its attention from Earth to the wider cosmos. In fact, Segert imagines the first missions could ‘timeshare’ between Earth and astronomical observation. “When the telescope flies into the shadow of the Earth and so can’t take pictures of the ground, we could turn it around and observe astronomical targets,” he says.

Future versions could be sent to other planets. As the telescope is so lightweight, it could be mounted on a Mars Express-sized spacecraft and used to take pictures showing details as small as 30 cm across on the Martian surface.

Although the prototype contains a respectable 50 cm-diameter mirror, Segert believes that it can scaled up in the future to achieve space telescopes bigger than the Hubble Space Telescope but still at a fraction of the cost. “If we did that,” says Segert, “the astronomers would be in heaven.”

Original Source: ESA Portal

What’s Making Martian Methane?

Frosted southern plains in early spring. Image credit: MSSS/JPL/ NASA Click to enlarge
The detections of methane in the martian atmosphere have challenged scientists to find a source for the gas, which is usually associated with life on Earth. One source that can be ruled out is ancient history: Methane can survive only 600 years in the martian atmosphere before sunlight will destroy it.

If the global concentration of methane on Mars is 10 ppb, then an average of 4 grams of methane is being destroyed every second by sunlight. That means about 126 metric tons of methane must be produced each year to ensure a steady concentration of 10 ppb.

There is an outside chance that the methane is being delivered to Mars by comets, asteroids, or other debris from space. Calculations show that micrometeorites are likely to deliver only 1 kilogram of methane a year — far short of the 126-ton replacement level. Comets could deliver a huge slug of methane, but the interval between major comet impacts averages 62 million years, so it’s unlikely that any comet delivered methane within the past 600 years.

If we can rule out methane delivery, then the methane must be manufactured on Mars. But is the source biology, or processes unassociated with life?

A small percentage of Earth’s methane is made through non-biological (“abiogenic”) interactions between carbon dioxide, hot water and certain rocks. Could this be occurring on Mars? Perhaps, says James Lyons of the Institute for Geophysics and Planetary Physics at UCLA.

These reactions require only rock, water, carbon and heat, but on Mars, where would the heat come from? The planet’s surface is stone cold, averaging minus 63 degrees C. Volcanoes could be a source of heat. Geologists think the most recent eruption on Mars was at least 1 million years ago — recent enough to suggest that Mars is still active, and therefore hot deep below the surface.

A trickle of methane averaging 4 grams per second could come from such a geological hot spot. But any martian hot spot must be deep and well-insulated from the surface, since the Thermal Emission Imaging System on Mars Odyssey found no locations that are at least 15 degrees C warmer than the surroundings. However, Lyons thinks it’s still possible that a deep body of magma could be supplying the heat.

In one computer model of simplified martian geology, a cooling body of magma 10 kilometers deep, 1 kilometer wide, and 10 kilometers long created the 375 to 450 degrees C temperature that drives abiogenic methane generation at mid-ocean ridges on Earth. Such a body of hot rock, Lyons says, “is perfectly sensible, there’s nothing strange about it,” because Mars probably retains some heat from planetary formation, much like Earth.

“It encourages us to think that this is a plausible scenario for explaining methane on Mars, and we would not see the signature of that dike (body of hot rock) on the surface,” says Lyons. “That’s the angle we are pursuing; it’s the simplest, most direct explanation for the methane detected.”

Although no one can rule out abiogenic sources for the methane on Mars, when you find methane on Earth, you are usually seeing the work of methanogens, ancient anaerobic microbes that process carbon and hydrogen into methane. Could methanogens live on Mars?

To find out, Timothy Kral, associate professor of biological sciences at the University of Arkansas, began growing five types of methanogens 12 years ago in volcanic soil chosen to simulate martian soil. He’s now shown that methanogens can survive for years on the granular, low-nutrient soil, although when grown in Mars-like conditions, at just 2 percent of Earth’s atmospheric pressure, they become desiccated and go dormant after a couple of weeks.

“The soil tends to dry out, and we have been able to find viable cells; they are still alive, but they don’t produce methane anymore,” Kral says.

Methanogens need a steady source of carbon dioxide and hydrogen. While carbon dioxide is abundant on Mars, “hydrogen is a question mark,” Kral says.

Vladimir Krasnopolsky, a research professor at Catholic University of America in Washington D.C., detected 15 parts per million of molecular hydrogen in the atmosphere of Mars. It is possible that this hydrogen is escaping from a deep source in the martian interior which methanogens could use.

If methanogens are deep inside Mars, the methane gas they produce would slowly rise toward the surface. Eventually it could reach a pressure-temperature condition where it would get trapped in ice crystals, forming methane hydrate.

“If there were a subsurface biosphere, methane hydrate would be an inevitable consequence, if things behave as they do on Earth,” says Stephen Clifford of the Lunar and Planetary Institute in Houston, Texas.

And there’s a fringe benefit, Clifford adds. Methane hydrates, “would be an insulating blanket that would substantially reduce the thickness of frozen ground on Mars, from several kilometers at the equator, to maybe less than a kilometer.” In other words, methane hydrate would both store evidence of life and insulate any life that remained from the ultra-cold surface temperatures.

Although data on conditions a kilometer or so below the martian surface are non-existent, the growing picture of the complexity, size and adaptability of Earth’s underground biosphere certainly improves the chance that life exists in comparable conditions inside Mars. Earth’s underground biosphere is composed largely of microbes, some of which live at depths, pressures and chemical conditions once thought inhospitable to life.

Deep inside Mars may be a hardscrabble place to make a living, but methanogens are no wimps, Kral says. “They are tough, durable. The fact that they have been around probably since the beginning of life on Earth, and continue to be the predominant life form below the surface and deep in the oceans, means they are survivors, they are doing extremely well.”

Original Source: NASA Astrobiology

Can You Make a Better Glove?

An astronaut’s pair of gloves. Image credit: NASA. Click to enlarge
NASA, in collaboration with the Volanz Aerospace Inc./Spaceflight America (Volanz), today announced a new Centennial Challenges prize competition.

The Astronaut Glove Challenge award will go to the team that can design and manufacture the best performing glove within competition parameters. The $250,000 purse will be awarded at a competition scheduled for November 2006, when competing teams test their glove designs against each other.

For the Challenge, teams must develop the bladder-restraint portion of an astronaut glove that is strong, easy on the hands, and gives the operator a high degree of dexterity.

“Reducing space suit glove fatigue is a critical technological goal that, if successful, would have an important impact on astronaut performance and mission planning,” said NASA’s acting Associate Administrator for the Exploration Systems Mission Directorate, Douglas Cooke.

Each team will provide two gloves for three key tests. First, the forces required to move the fingers and thumb on each glove will be measured. Gloves requiring the least force will be awarded more points. Second, each team will perform standardized dexterity tasks in a depressurized glove box. Teams completing the most tasks within a specified time will win the most points. Third, one glove from each team will be subjected to a burst test. Glove designs that withstand greater internal pressures will be awarded more points.

The team with the glove design that wins the most points, while exceeding the performance of existing astronaut glove technologies will win the contest.

NASA’s Centennial Challenges promotes technical innovation through a novel program of prize competitions. It is designed to tap the nation’s ingenuity to make revolutionary advances to support the Vision for Space Exploration and NASA goals.

“With this competition, we are continuing to develop Centennial Challenges’ base of smaller, targeted technology prizes and laying the ground work for our larger competitions,” said NASA’s Centennial Challenges program manager Brant Sponberg.

The Astronaut Glove Challenge will be administered and executed by Volanz at no cost to NASA. Volanz will officially kick-off the challenge at a conference in November in Houston.

“New technologies and innovations will have to be developed quickly to improve the wearability and dexterity of astronaut gloves. This challenge will help NASA meet this key requirement in support of the Vision for Space Exploration,” said Volanz chairman and chief executive officer, Alan Hayes. “Like other Centennial Challenges’ competitions, the Astronaut Glove Challenge will encourage innovation that will greatly enhance our capabilities in this area,” he added.

The Centennial Challenges program is managed by NASA’s Exploration Systems Mission Directorate. Volanz is a non-profit Maryland corporation formed in 1998 to provide space science educational and research programs for researchers, educators, and students.

For more information about Centennial Challenges on the Internet, visit:
http://centennialchallenges.nasa.gov

For more information about NASA and agency programs on the Internet, visit:
http://www.nasa.gov/home/index.html

For information about Volanz Aerospace Inc. on the Internet, visit:
www.spaceflightamerica.org

Original Source: NASA News Release

Discovery Blasts Off Successfully

After being grounded for more than two years, NASA’s shuttle fleet has returned to service with today’s dramatic launch of the space shuttle Discovery. It lifted off right on schedule, at 1439 UTC (10:39 am EDT), and quickly sped up through the light clouds above the Kennedy Space Center. More than 100 cameras were watching the launch from every available angle, and NASA will be examining the photographs carefully to see if any debris fell off the tank and struck the shuttle. Discovery will now link up with the International Space Station in a couple of days.

Measures to Prevent the Contamination of Mars

Crater Holden and Uzboi Vallis. Image credit: ESA/DLR/FU Berlin. Click to enlarge
Over the coming decade, NASA should develop and implement new methods and requirements to detect and eliminate microorganisms on robotic spacecraft sent to Mars to prevent possible contamination of the planet, says a new report from the National Academies’ National Research Council. If microbes aboard a spacecraft were to survive the trip to Mars and grow there, they could interfere with scientific investigations to detect any life that might be native to Mars. Existing techniques for cleaning spacecraft are outdated and typically eliminate only a fraction of microorganisms, said the committee that wrote the report.

Recent scientific findings suggest that liquid water could be present at many locations on Mars and that some organisms on Earth might survive in extreme, Mars-like conditions — such as very low temperatures and high salt concentrations. These discoveries have bolstered the case that Mars could be — or have been — hospitable to life and have created urgency to update policies and practices to prevent Mars contamination, the report says.

“Ongoing Mars missions have shown that the planet may have environments where some Earth microbes could grow,” said Christopher F. Chyba, committee chair and professor of astrophysics and international affairs at Princeton University, Princeton, N.J. “Although we don’t know for sure if this could happen, we need to understand whether liquid water exists in Martian near-surface environments, as well as the nature of microorganisms that are in our clean rooms and spacecraft. It will take a while to carry out the needed research and development, so we need to start in earnest now.”

NASA currently uses screening techniques that detect heat-resistant and spore-forming bacteria on spacecraft and then reduces their numbers by cleaning the spacecraft and, in certain circumstances, baking components with dry heat. But these screening methods are not designed to give a comprehensive tally of the microbes present on the spacecraft, and dry heat can be applied only to spacecraft materials that can withstand high temperatures, the report notes.

NASA should sponsor new research efforts aimed at preventing Mars contamination, the committee said, such as new techniques for detecting biological molecules that do not require time for growing laboratory cultures and could speed spacecraft sterilization and assembly in clean rooms. Also, methods that determine genetic sequences of organisms and link them to known microbial species could allow NASA to tailor sterilization techniques toward spacecraft contaminants of greatest concern. NASA should also investigate alternative cleaning methods — such as the use of radiation or vapor disinfectants — for their effectiveness in killing different types of microorganisms and for their effects on various spacecraft materials.

NASA should develop a certification process to compare detection and cleaning methods and select the most promising ones, begin testing and validating improved techniques within the next three years, and fully implement selected new techniques in time for spacecraft to launch in 2016. Until NASA conducts the research needed to transition to a modern approach for planetary protection, the agency should apply more stringent sterilization levels to all Mars landing spacecraft, the committee said. An independent review panel should be created by NASA and meet every three years to review new knowledge about the Martian environment and recommend updates, as needed, to Mars protection requirements.

The study was sponsored by NASA. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provide science and technology advice under a congressional charter. A committee roster follows.

Original Source: The National Academies News Release

Strange Ice Boulders on Enceladus

The southern polar terrain of Enceladus. Image credit: NASA/JPL/SSI. Click to enlarge
NASA’s Cassini spacecraft has obtained new, detailed images of the south polar region of Saturn’s moon Enceladus. The data reveal distinctive geological features and the most youthful terrain seen on the moon. These findings point to a very complex evolutionary history for Saturn’s brightest, whitest satellite.

Cassini’s July 14 flyby brought it within 175 kilometers (109 miles) of the surface of the icy moon. The close encounter revealed a landscape near the south pole almost entirely free of impact craters. The area is also littered with house-sized ice boulders carved by unique tectonic patterns found only in this region of the moon.

As white as fresh snow, Enceladus has the most reflective surface in the solar system. Previous Cassini flybys revealed Enceladus, in contrast to Saturn’s other icy moons, has lightly cratered regions, fractured plains and wrinkled terrain.

The new findings add to the story of a body that has undergone multiple episodes of geologic activity spanning a considerable portion of its lifetime. The moon’s southernmost latitudes have likely seen the most recent activity.

These same latitudes may also bear the scars of a shift in the moon’s spin rate. If true, this speculation may help scientists understand why Enceladus has a tortured-looking surface, with pervasive crisscrossing faults, folds and ridges. The most remarkable images show ice blocks about 10 to 100 meters (33 to 328 feet) across in a region that is unusual in its lack of the very fine-grained frost that seems to cover the rest of Enceladus.

“A landscape littered with building-sized blocks was not expected,” said Dr. Peter Thomas, an imaging-team member from Cornell University, Ithaca, N.Y. “The minimal cover of finer material and the preservation of small, crossing fracture patterns in the surrounding areas indicate that this region is young compared to the rest of Enceladus.”

False color composites of this region, created from the most recent images, show the largest exposures of coarse-grained ice fractures seen anywhere on the moon, which also supports the notion of a young surface at southern latitudes. Some of the latest images may hint at the answer. The images revealed additional examples of a distinctive “Y-shaped” tectonic feature on Enceladus. In this unusual element, parallel ridges and valleys appear to systematically fold and deform around the south polar terrains.

“These tectonic features define a boundary that isolates the young, south polar terrains from older terrains on Enceladus,” noted Dr. Paul Helfenstein, an associate of the imaging team also at Cornell University. “Their placement and orientation may tell us a very interesting story about the way the rotation of Enceladus has evolved over time and what might have provided the energy to power the geologic activity that has wracked this moon.”

The apparent absence of sizable impact craters also suggests the south pole is younger than other terrain on Enceladus. All these indications of youth are of great interest to scientists, who have long suspected Enceladus as one possible source of material for Saturn’s extensive and diffuse E ring, which coincides with the moon’s orbit. Young terrain requires a means to generate the heat needed to modify the surface. Other Cassini instrument teams are working to understand data about the temperature, composition, particles and magnetic field. Together with image interpretation, these data can create a more complete picture.

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 mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

These Cassini images are available on the Web at: http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

Original Source: NASA/JPL/SSI News Release