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Category Archives: Space Station

Yeast Rising to the Space Station

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Chefs across the globe may not know it yet, but their baker's yeast just left the kitchen and blasted off into low Earth orbit. Hitching a ride on the space shuttle Atlantis on July 8, 2011, the samples will be grown on the International Space Station as part of the Genotypic and Phenotypic Changes in Yeast Related to Selective Growth Pressures Unique to Microgravity or Micro-4 investigation. Capable of raising more than just breads, this useful organism will help researchers better understand the impact of the space environment on live cells in humans.

This yeast -- S. cerevisiae -- has been of use since the ancient Egyptians first figured out how to harness it for wine and bread making. In modern times it is still used for baking and was the first organism to have its genome fully sequenced. Scientists hope that by studying the changes of yeast in microgravity, they will better understand the changes human cells may experience during long-duration spaceflight. Gaining better knowledge of genetic alterations by studying yeast growth during this microgravity research may also help in understanding how these changes could manifest in human disease here on Earth.

This investigation is a collaboration with BioServe Space Technologies, Durham Veterans Affairs Medical Center, and the University of Toronto. According to Michael Costanzo, Ph.D. and one of the co-investigators for Micro-4 at the University of Toronto, the similarities between human cells and the yeast's genetic makeup makes it ideal for study in space. "We are examining which genes are important for cell growth and survival in a zero gravity environment. The results of our 'yeastnaut' experiments may provide insight into which set of human genes are important and how these genes work together to help organisms/humans deal with extreme environments associated with space travel -- such as zero-gravity and elevated radiation."

Two different sets of experiments will take place as part this study. The first will grow yeast cells in petri dishes using temperature-controlled chambers. On July 12, scientists on the ground remotely changed the temperature from 4° C to 30° C -- the optimal temperature for yeast cell growth -- to activate the on-orbit samples. The cells continue to grow for 48 hours before the temperature is cooled again and the samples are stowed for return to Earth for analysis. The second experiment includes the use of a liquid media to grow the yeast. During the mission, astronauts will transfer the samples to fresh liquid media twice before stowing them, as well.

Both studies will look at how cells adapt to the space environment using the yeast deletion series -- a collection of ? 5000 yeast strains, each of which has been deleted for a different gene. In other words, a collection of yeast cells that have been genetically engineered to help scientists to figure out what genes are important for specific responses to microgravity. The goal is to see which strain is best suited to spaceflight, showing researchers which genetic traits are capable of survival in microgravity.

The convenience of yeast as a test subject also provides an important avenue to understanding how living things adapt to space. Due to the small number of humans who have traveled in space, as well as the short duration of their exposure, little is known about the effects of long-term zero gravity on biological systems. "In contrast," said Corey Nislow, Ph.D. and co-investigator from the University of Toronto, "in both our experiments, we have huge sample sizes -- millions of cells -- and they will be monitored for 20 generations, the equivalent of 400 human years."

Control studies will take place on the ground at Kennedy Space Center, Fla. The space shuttle will also carry an identical set of samples to those that will transfer to the space station. These duplicate samples, however, will remain on the shuttle to be "flown, not grown," explained Nislow. Returning to Earth with Atlantis, these duplicate samples will be activated on the ground to investigate growth in tandem timing to those aboard the station.

While the STS-135 mission is the final shuttle flight for NASA, scientists for this study will not have to wait for the certification of new flight vehicles to continue their research. The hardware designed and used for Micro-4 is not limited to the harsh environment of space, but may also find use in Earth-based extremes for future yeast experiments. "It is important to remember that it's fun to fantasize about life in other parts of the solar system, yet we sometimes overlook the fact that life thrives at incredible extremes here on Earth," commented Nislow. "Such as in boiling water around ocean vents, in the polar ice caps, and even in environments so acidic that they would melt metal!"

For more information visit http://www.nasa.gov/mission_pages/station/research/news/Micro_4.html

La Niña’s Exit Leaves Climate Forecasts in Limbo

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It's what Bill Patzert, a climatologist and oceanographer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., likes to call a "La Nada" – that puzzling period between cycles of the El Niño-Southern Oscillation climate pattern in the Pacific Ocean when sea surface heights in the equatorial Pacific are near average.

The comings and goings of El Niño and La Niña are part of a long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator. For the past three months, since last year's strong La Niña event dissipated, data collected by the U.S.-French Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite have shown that the equatorial Pacific sea surface heights have been stable and near average. Elsewhere, however, the northeastern Pacific Ocean remains quite cool, with sea levels much lower than normal. The presence of cool ocean waters off the U.S. West Coast has also been a factor in this year's cool and foggy spring there.

The current state of the Pacific is shown in this OSTM/Jason-2 image, based on the average of 10 days of data centered on June 18, 2011. The image depicts places where Pacific sea surface height is higher (warmer) than normal as yellow and red, while places where the sea surface is lower (cooler) than normal are shown in blue and purple. Green indicates near-normal conditions. Sea surface height is an indicator of how much of the sun's heat is stored in the upper ocean.

For oceanographers and climate scientists like Patzert, "La Nada" conditions can bring with them a high degree of uncertainty. While some forecasters (targeting the next couple of seasons) have suggested La Nada will bring about "normal" weather conditions, Patzert cautions previous protracted La Nadas have often delivered unruly jet stream patterns and wild weather swings.

In addition, some climatologists are pondering whether a warm El Niño pattern (which often follows La Niña) may be lurking over the horizon. Patzert says that would be perfectly fine for the United States.

"For the United States, there would be some positives to the appearance of El Niño this summer," Patzert said. "The parched and fire-ravaged southern tier of the country would certainly benefit from a good El Niño soaking. Looking ahead to late August and September, El Niño would also tend to dampen the 2011 hurricane season in the United States. We've had enough wild and punishing weather this year. Relief from the drought across the southern United States and a mild hurricane season would be very welcome."

Jason-2 scientists will continue to monitor Pacific Ocean sea surface heights for signs of El Niño, La Niña or prolonged neutral conditions.

For more information visit http://www.nasa.gov/topics/earth/features/lanada20110629.html

NASA’s Hubble Makes One Millionth Science Observation

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NASA's Hubble Space Telescope crossed another milestone in its space odyssey of exploration and discovery. On Monday, July 4, the Earth-orbiting observatory logged its one millionth science observation during a search for water in an exoplanet's atmosphere 1,000 light-years away.

"For 21 years Hubble has been the premier space science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines," said NASA Administrator Charles Bolden. He piloted the space shuttle mission that carried Hubble to orbit. "The fact that Hubble met this milestone while studying a faraway planet is a remarkable reminder of its strength and legacy."

Although Hubble is best known for its stunning imagery of the cosmos, the millionth observation is a spectroscopic measurement, where light is divided into its component colors. These color patterns can reveal the chemical composition of cosmic sources.

Hubble's millionth exposure is of the planet HAT-P-7b, a gas giant planet larger than Jupiter orbiting a star hotter than our sun. HAT-P-7b, also known as Kepler 2b, has been studied by NASA's planet-hunting Kepler observatory after it was discovered by ground-based observations. Hubble now is being used to analyze the chemical composition of the planet’s atmosphere.

This is an artist's concept of that planet, HAT-P-7b. It is a "hot Jupiter" class planet orbiting a star that is much hotter than our sun. Hubble Space Telescope's millionth science observation was trained on this planet to look for the presence of water vapor and to study the planet's atmospheric structure via spectroscopy. (Credit: NASA; ESA; G. Bacon, STScI)

"We are looking for the spectral signature of water vapor. This is an extremely precise observation and it will take months of analysis before we have an answer," said Drake Deming of the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md. "Hubble demonstrated it is ideally suited for characterizing the atmospheres of exoplanets, and we are excited to see what this latest targeted world will reveal."

Hubble was launched April 24, 1990, aboard space shuttle's Discovery's STS-31 mission. Its discoveries revolutionized nearly all areas of astronomical research from planetary science to cosmology. The observatory has collected more than 50 terabytes of data to-date. The archive of that data is available to scientists and the public at:

› http://hla.stsci.edu/

Hubble's odometer reading includes every observation of astronomical targets since its launch and observations used to calibrate its suite of instruments. Hubble made the millionth observation using its Wide Field Camera 3, a visible and infrared light imager with an on-board spectrometer. It was installed by astronauts during the Hubble Servicing Mission 4 in May 2009.

"The Hubble keeps amazing us with groundbreaking science," said Sen. Barbara A. Mikulski, the chairwoman of the Senate Commerce, Justice, Science and Related Agencies Appropriations Subcommittee that funds NASA. "I championed the mission to repair and renew Hubble not just to get one million science observations, but also to inspire millions of children across the planet to become our next generation of stargazers, scientists, astronauts and engineers."

For more information visit http://www.nasa.gov/mission_pages/hubble/science/millionth.html

Punching Holes in the Sky

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Scientists, photographers and amateur cloud watchers have been looking up with wonderment and puzzlement at "hole punch" clouds for decades. Giant, open spaces appear in otherwise continuous cloud cover, presenting beautiful shapes but also an opportunity for scientific investigation. A new paper published last week in Science inquires into how the holes get punched – airplanes are the culprit – and into the potential for the phenomenon's link to increased precipitation around major airports.

"It appears to be a rather widespread effect for aircraft to inadvertently cause some measureable amount of rain or snow as they fly through certain clouds," said lead author Andrew Heymsfield of the National Center for Atmospheric Research, Boulder, Co. "This is not necessarily enough precipitation to affect global climate, but it is likely to be noticeable around major airports in the midlatitudes."

NASA Langley Research Center cloud specialist Patrick Minnis was one of the co-authors on the paper. NASA satellites Aqua, Terra, CALIPSO and CloudSat were used in the analysis. The research was also partly funded by NASA grants.

Picture a layer of supercooled liquid water clouds stretching across the sky, like a sheet, in subfreezing temperatures. An airliner gaining altitude punches through the cloud layer, and leaves behind a void as if by a circular cookie-cutter. In some cases, the shape left behind is more ragged, or even more rectangular or canal-like. But the nearly perfect circle often makes for the most compelling sight in the sky. The ice particles grow at the expense of the supercooled water droplets and fall out of the cloud as snow. If the cloud layer is thin or if the water is not replenished the snow leaves a hole in the cloud.

"In other conditions, it may produce a somewhat continuous snow line," Minnis said, as has been observed around the Denver airport.

Web sites on the Internet are now devoted to collecting pictures of hole punch clouds from around the world. Scientists first reported observing hole punch clouds in the 1940s, according to the Science paper. They often lead to false reports of UFOs or rocket launches. But aside from being a notch in the belt for cloud-watchers, the "mechanisms of formation and the physics of the development, duration, and thus the extent of their effect have largely been ignored." Heymsfield and the other authors studied satellite images of hole punch clouds and then used computer models to simulate how the holes evolved after formation. Whether a plane is climbing or flying level through the cloud layer determines whether a "hole" is "punched" or a "canal" is "dug" through the clouds.

In addition to describing the physics of how planes form the holes in specific cloud types, the Science paper also looks at this "inadvertent" cloud seeding. The authors suggest that the effect is not large enough to have an impact on global climate, but that "regionally near major airports in midlatitudes during cool weather months it may lead to enhanced precipitation at the ground."

For more information visit http://www.nasa.gov/topics/earth/features/hole-punch.html

Dark Fireworks on the Sun

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On June 7, 2011, Earth-orbiting satellites detected a flash of X-rays coming from the western edge of the solar disk. Registering only "M" (for medium) on the Richter scale of solar flares, the blast at first appeared to be a run-of-the-mill eruption--that is, until researchers looked at the movies.

"We'd never seen anything like it," says Alex Young, a solar physicist at the Goddard Space Flight Center. "Half of the sun appeared to be blowing itself to bits."

"In terms of raw power, this really was just a medium-sized eruption," says Young, "but it had a uniquely dramatic appearance caused by all the inky-dark material. We don't usually see that."

Solar physicist Angelos Vourlidas of the Naval Research Lab in Washington DC calls it a case of "dark fireworks."

"The blast was triggered by an unstable magnetic filament near the sun's surface," he explains. "That filament was loaded down with cool plasma, which exploded in a spray of dark blobs and streamers. "Cool" has a special meaning on the sun: The plasma blobs registered a temperature of 20,000 Kelvin or less. That is relatively cool. Most of the surrounding gas had temperatures between 40,000 K and 1,000,000 K.

The plasma blobs were as big as planets, many larger than Earth. They rose and fell ballistically, moving under the influence of the sun's gravity like balls tossed in the air, exploding "like bombs" when they hit the stellar surface.

Some blobs, however, were more like guided missiles. "In the movies we can see material 'grabbed' by magnetic fields and funneled toward sunspot groups hundreds of thousands of kilometers away," notes Young.

SDO also detected a shadowy shock wave issuing from the blast site. The 'solar tsunami' propagated more than halfway across the sun, visibly shaking filaments and loops of magnetism en route. [91 MB Quicktime] Long-range action has become a key theme of solar physics since SDO was launched in 2010. The observatory frequently sees explosions in one part of the sun affecting other parts. Sometimes one explosion will trigger another ... and another ... with a domino sequence of flares going off all around the star.

"The June 7th blast didn't seem to trigger any big secondary explosions, but it was certainly felt far and wide," says Young.

It's tempting to look at the movies and conclude that most of the exploded material fell back--but that wouldn't be true, according to Vourlidas. "The blast also propelled a significant coronal mass ejection (CME) out of the sun's atmosphere."

He estimates that the cloud massed about 4.5 x1015 grams, placing it in the top 5% of all CMEs recorded in the Space Age. For comparison, the most massive CME ever recorded was 1016 grams, only a factor of ~2 greater than the June 7th cloud. The amount of material that fell back to the sun on June 7 was approximately equal to the amount that flew away, Vourlidas says.

As remarkable as the June 7th eruption seems to be, Young says it might not be so rare. "In fact," he says, "it might be downright common."

Before SDO, space-based observatories observed the sun with relatively slow cadences and/or limited fields of view. They could have easily missed the majesty of such an explosion, catching only a single off-center snapshot at the beginning or end of the blast to hint at what actually happened.

If Young is right, more dark fireworks could be in the offing. Stay tuned.

For more information visit http://www.nasa.gov/mission_pages/sunearth/news/dark-fireworks.html

First iPhone Flying on Last Shuttle

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There is at least one first involved with space shuttle Atlantis’ STS-135 mission, a flight notable for its lasts: the crew is taking the first iPhone into space to help with experiments aboard the International Space Station.

A Houston company called Odyssey Space Research developed an application for the Apple smartphone that is meant to help the astronauts track their scientific results and perhaps one day aid navigation. The device will be housed inside a small research platform built by NanoRacks. The platform will be placed inside the station.

The app, called SpaceLab for iOS, is even available to Earthbound smartphone users to perform the same experiments with the software simulating microgravity.

According to the company, the software was designed with the iPhone's unique attributes in mind, such as the gyro, accelerometer, cameras and chip.

Atlantis is to launch July 8 from NASA's Kennedy Space Center in Florida on a mission to deliver supplies and experiments to the space station.

Along with the first iPhone, the crew of Atlantis is bringing along numerous items commemorating what will be the final mission of Space Shuttle Program. For instance, a flag from the first shuttle flight in 1981 will be carried to the station and left there until the first commercial spaceflight to the station, when NASA astronauts will retrieve it. The astronauts, Commander Chris Ferguson, Pilot Doug Hurley and Mission Specialists Sandy Magnus and Rex Walheim, have allocated a number of unique items that will become commemoratives for numerous organizations after they return to Earth.

For example, American flags from the Delaware Valley Historic Aircraft Association, Key Peninsula Middle School in Lake Bay, Washington, and a fire station in Houston are to orbit the Earth for 12 days before being handed over to their sponsors as symbols of inspiration.

The U.S. Honor Flag also will fly aboard Atlantis. Begun as a tribute following the Sept. 11, 2001, terrorists' attacks, the American flag serves as a traveling memorial to heroes who lost their lives while serving their communities and country.

Among the unusual things headed into space is a recipe card from one of the dishes served at Astronaut Crew Quarters at NASA's Kennedy Space Center in Florida.

NASCAR is well-represented on the mission with a cap from Joe Gibbs Racing and black flags from Texas Motor Speedway and the NASCAR organization on the roster of items.

More than 500 STS-135 mission patches are tucked inside Atlantis for the flight, a common take-along for all shuttle missions, along with 800 small American flags that typically are handed out after a mission as awards and recognitions.


When the crew returns, the items will be unpacked from lockers inside the shuttle and returned to the astronauts who often make personal visits to hand them back to their owners.

The custom of carrying mementoes into space began in the days of the Mercury missions, when an astronaut would take a roll of coins or some other small tokens into space. The Apollo astronauts carried items to the moon and back during their missions.

The tradition is not expected to end with the end of the shuttle program. When SpaceX launched its Dragon capsule last year, for instance, it carried commemorative items inside, most notably a wedge of cheese.

The items taken and returned from space rest in schools, museums and facilities all over the world and are often prominently displayed to inspire people to think of the adventures they might one day take themselves.

For more information visit http://www.nasa.gov/mission_pages/shuttle/behindscenes/whatsgoingup135.html

Plasma Spectrometer Operations on Hold

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Mission managers for NASA's Cassini spacecraft suspended operation of the Cassini plasma spectrometer instrument on Tuesday, June 14, 2011, after a series of voltage shifts on the spacecraft. They will determine when the instrument can resume collecting data.

The Cassini spacecraft is designed to operate with a "balanced" voltage source to create a tolerance to short circuits. On May 1, a voltage shift occurred, most likely explained by a short circuit happening somewhere in the system. On June 11, a voltage shift in the opposite direction occurred, indicating an additional short circuit. In both cases, all instruments and engineering subsystems continued to operate properly.

Analysis of telemetry data from the spacecraft by the engineering team pointed to the Cassini plasma spectrometer instrument as the cause of the voltage shifts. The instrument has additional capacitors in the power lines for noise reduction. The concern was that one or more of these capacitors may have short-circuited, which would cause the voltage to shift and explain the observed changes. Although the instrument was operating properly, engineers decided to turn it off as a precaution until the events could be better understood.

The suspension of the plasma spectrometer operations is not expected to affect other science data gathering or navigation. The plan is to resume normal plasma spectrometer operations after further analysis is completed to understand the cause of the issue better.

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.

For more information visit http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20110615.html

Small Asteroid to Whip Past Earth on June 27, 2011

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Near-Earth asteroid 2011 MD will pass only 12,000 kilometers (7,500 miles) above the Earth's surface on Monday June 27 at about 9:30 EDT. The asteroid was discovered by the LINEAR near-Earth object discovery team observing from Socorro, New Mexico. This small asteroid, only 5-20 meters in diameter, is in a very Earth-like orbit about the Sun, but an orbital analysis indicates there is no chance it will actually strike Earth on Monday. If a rocky asteroid the size of 2011 MD were to enter Earth's atmosphere, it would be expected to burn up high in the atmosphere and cause no damage to Earth's surface. The accompanying diagram gives a view of the asteroid's trajectory from the general direction of the Sun. This view indicates that 2011 MD will reach its closest Earth approach point in extreme southern latitudes (in fact over the southern Atlantic Ocean). The incoming trajectory leg passes several thousand kilometers outside the geosynchronous ring of satellites and the outgoing leg passes well inside the ring. One would expect an object of this size to come this close to Earth about every 6 years on average. For a brief time, it may be bright enough to be seen even with a modest-sized telescope.

For more information visit http://www.nasa.gov/topics/solarsystem/features/neo20110624.html

NASA Will Host 150 People for Tweetup at Launch of Jupiter-Bound Mission

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NASA will host a two-day launch Tweetup for 150 of its Twitter followers on Aug. 4-5 at the agency's Kennedy Space Center in Florida. The Tweetup is expected to culminate in the launch of the Jupiter-bound Juno spacecraft aboard an Atlas V rocket.

The launch window opens at 8:39 a.m. PDT (11:39 a.m. EDT) on Aug. 5. The spacecraft is expected to arrive at Jupiter in 2016. The mission will investigate the gas giant's origins, structure, atmosphere and magnetosphere. Juno's color camera will provide close-up images of Jupiter, including the first detailed glimpse of the planet's poles.

The Tweetup will provide @NASA Twitter followers with the opportunity to tour the Kennedy Space Center Visitor Complex; speak with scientists and engineers from the Juno and other upcoming missions; and, if all goes as scheduled, view the spacecraft launch. The event also will provide participants the opportunity to meet fellow tweeps and members of NASA's social media team.

Juno is the second of four space missions launching this year, making 2011 one of the busiest ever in planetary exploration. Aquarius was launched June 10 to study ocean salinity; Grail will launch Sept. 8 to study the moon's gravity field; and the Mars Science Laboratory/Curiosity rover will head to the Red Planet no earlier than Nov. 25.

Tweetup registration opens at noon PDT (3 p.m. EDT) on Friday, June 24, and closes at noon PDT (3 p.m. EDT) on Monday, June 27. NASA will randomly select 150 participants from online registrations. For more information about the Tweetup and registration, visit: http://www.nasa.gov/connect/tweetup/tweetup_jpl_08-04-2011.html .

For information about connecting and collaborating with NASA, visit: http://www.nasa.gov/connect .

Juno's principal investigator is Scott Bolton of the Southwest Research Institute in San Antonio. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the mission.

For more information visit http://www.nasa.gov/mission_pages/juno/news/juno20110624.html

JPL-Developed Clean Energy Technology Moves Forward

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A team of scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., in partnership with the University of Southern California in Los Angeles, developed a Direct Methanol Fuel Cell technology for future Department of Defense and commercial applications. Recently, USC and the California Institute of Technology in Pasadena, which manages JPL for NASA, awarded a license to SFC Energy, Inc., the U.S. affiliate of SFC Energy AG. The non-exclusive license for the technology will facilitate the expansion of the company's methanol fuel cell products into the U.S. market.

This novel fuel cell technology uses liquid methanol as a fuel to produce electrical energy, and does not require any fuel processing. Pure water and carbon dioxide are the only byproducts of the fuel cell, and no pollutants are emitted. Direct Methanol Fuel Cells offer several advantages over other current fuel cell systems, especially with regard to simplicity of design and higher energy density. Current systems rely on hydrogen gas, a substance that is more difficult to transport and store.

"JPL invented the Direct Methanol Fuel Cell concept and also made significant contributions to all the facets of the technology. These contributions include: development of advanced catalyst materials, high-performance fuel cell membrane electrode assemblies, compact fuel cell stacks, and system designs," said JPL Power Technology Program Manager Rao Surampudi. He explained that USC worked with JPL in the development and advancement of this technology for defense and commercial applications.

Over the years, those applications have expanded from the original defense applications to include such uses as battery chargers for consumer electronics, electric vehicles, stand-alone power systems, and uninterrupted/emergency power supplies.

"We are looking forward to working closely with the fuel cell industry to further develop this technology to meet future market needs," said Erik Brandon, current Electrochemical Technologies group supervisor at JPL.

From 1989 to 1998, the Defense Advanced Research Projects Agency (DARPA) funded JPL and USC to develop direct methanol fuel cells for future defense applications. Inventors on the JPL team include Surampudi, Sri. R. Narayanan, Harvey Frank, Thomas Valdez, Andrew Kindler, Eugene Vamos and Gerald Halpert. The USC inventor team includes G.K. Surya Prakash, Marshall Smart and Nobel Laureate George Olah.

More information is available at: http://www.ott.caltech.edu/

"This fuel cell may well become the power source of choice for energy-efficient, non-polluting military and consumer applications," said Gerald Halpert, former Electrochemical Technologies group supervisor at JPL.

The Caltech and NASA technology transfer programs are designed to help U.S. companies improve their competitive positions in the global economy by transferring JPL technology into the marketplace.

For more information visit http://www.nasa.gov/topics/technology/features/methanol20110526.html

Gardening in Space with HydroTropi

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Plants are fundamental to life on Earth, converting light and carbon dioxide into food and oxygen. Plant growth may be an important part of human survival in exploring space, as well. Gardening in space has been part of the International Space Station from the beginning -- whether peas grown in the Lada greenhouse or experiments in the Biomass Production System. The space station offers unique opportunities to study plant growth and gravity, something that cannot be done on Earth.

The latest experiment that has astronauts putting their green thumbs to the test is Hydrotropism and Auxin-Inducible Gene expression in Roots Grown Under Microgravity Conditions, known as HydroTropi. Operations were conducted October 18-21, 2010. HydroTropi is a Japan Aerospace Exploration Agency (JAXA)-run study that looks at directional root growth. In microgravity, roots grow latterly or sideways, instead of up and down like they do under Earth’s gravitational forces.

Using cucumber plants (scientific name Cucumis sativus), investigators look to determine whether hydrotropic -- plant root orientation due to water—response can control the direction of root growth in microgravity. To perform the HydroTropi experiment, astronauts transport the cucumber seeds from Earth to the space station and then coax them into growth. The seeds, which reside in Hydrotropism chambers, undergo 18 hours of incubation in a Cell Biology Experiment Facility or CBEF. Then the crewmembers activate the seeds with water or a saturated salt solution, followed by a second application of water 4 to 5 hours later. The crew harvests the cucumber seedlings and preserves them using fixation tubes called Kenney Space Center Fixation Tubes or KFTs, which then store in one of the station MELFI freezers to await return to Earth.

The results from HydroTropi, which returns to Earth on STS-133, will help investigators to better understand how plants grow and develop at a molecular level. The experiment will demonstrate a plant’s ability to change growth direction in response to gravity (gravitropism) vs. directional growth in response to water (hydrotropism). By looking at the reaction of the plants to the stimuli and the resulting response of differential auxin -- the compound regulating the growth of plants -- investigators will learn about plants inducible gene expression. In space, investigators hope HydroTropi will show them how to control directional root growth by using the hydrotropism stimulus; this knowledge may also lead to significant advancements in agriculture production on Earth.

For more information visit http://www.nasa.gov/mission_pages/station/research/news/hydrotropi.html

NASA Scientists Theorize Titan Shaped By Weather, Not Ice Volcanoes

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Have the surface and belly of Saturn's smog-shrouded moon, Titan, recently simmered like a chilly, bubbling cauldron with ice volcanoes, or has this distant moon gone dead? In a newly published analysis, a pair of NASA scientists analyzing data collected by the Cassini spacecraft suggest Titan may be much less geologically active than some scientists think.

In the paper, published in the April 2011 edition of the journal Icarus, scientists conclude Titan's interior may be cool and dormant and incapable of causing active ice volcanoes.

"It would be fantastic to find strong evidence that clearly shows Titan has an internal heat source that causes ice volcanoes and lava flows to form," said Jeff Moore, lead author of the paper and a planetary scientist at NASA's Ames Research Center, Moffett Field, Calif. "But we find that the evidence presented to date is unconvincing, and recent studies of Titan’s interior conducted by geophysicists and gravity experts also weaken the possibility of volcanoes there."

Scientists agree that Titan shows evidence of having lakes of liquid methane and ethane, and valleys carved by these exotic liquids, as well as impact craters. However, a debate continues to brew about how to interpret the Cassini data about Titan. Some scientists theorize ice volcanoes exist and suggest energy from an internal heat source may have caused ice to rise and release methane vapors as it reached Titan’s surface.

But in the new paper, the authors conclude that the only features on Titan’s surface that have been unambiguously identified were created by external forces – such as objects hitting the surface and creating craters, wind and rain pummeling its surface, and the formation of rivers and lakes.

"Titan is a fascinating world," said Robert Pappalardo, a research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and former Cassini project scientist. "Its uniqueness comes from its atmosphere and organic lakes, but in this study, we find no strong evidence for icy volcanism on Titan."

In December 2010, a group of Cassini scientists presented new topographic data on an area of Titan called Sotra Facula, which they think makes the best case yet for a possible volcanic mountain that once erupted ice on Titan. Although Moore and Pappalardo do not explicitly consider this recent topographic analysis in their paper, they do not find the recent analysis of Sotra Facula to be convincing so far. It remains to be seen whether ongoing analyses of Sotra Facula can change minds.

Titan, Saturn's largest moon, is the only known moon to have a dense atmosphere, composed primarily of nitrogen, with two to three percent methane. One goal of the Cassini mission is to find an explanation for what, if anything, might be maintaining this atmosphere.

Titan's dense atmosphere makes its surface very difficult to study with visible-light cameras, but infrared instruments and radar signals can peer through the haze and provide information about both the composition and shape of the surface.

"Titan is most akin to Jupiter's moon Callisto, if Callisto had weather," Moore added. "Every feature we have seen on Titan can be explained by wind, rain, and meteorite impacts, rather than from internal heating."

Callisto is almost the exact same size as Titan. It has a cratered appearance and because of its cool interior, its surface features are not affected by internal forces. Moore and Pappalardo conclude that Titan also may have a cool interior, with only external processes like wind, rain and impacts shaping its surface."

The Cassini spacecraft, currently orbiting Saturn, continues to make fly-bys of Titan. Scientists will continue to explore Titan's mysteries, including investigations of the changes in the landscapes.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and several of its instruments were designed, developed and assembled at JPL.

For more information visit http://www.nasa.gov/topics/solarsystem/features/Titan_Ice_Volcanoes.html

MESSENGER Provides New Data about Mercury

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After nearly three months in orbit about Mercury, MESSENGER's payload is providing a wealth of new information about the planet closest to the Sun, as well as a few surprises.

The spacecraft entered orbit around Mercury on March 18, 2011 UTC, becoming the first spacecraft ever to do so. Tens of thousands of images of major features on the planet — previously seen only at comparatively low resolution — are now available in sharp focus. Measurements of the chemical composition of Mercury's surface are providing important clues to the origin of the planet and its geological history. Maps of the planet's topography and magnetic field are revealing new clues to Mercury's interior dynamical processes. And scientists now know that bursts of energetic particles in Mercury's magnetosphere are a continuing product of the interaction of Mercury's magnetic field with the solar wind.

This week, MESSENGER completed is first perihelion passage from orbit, its first superior solar conjunction from orbit, and its first orbit-correction maneuver. "Those milestones provide important context to the continuing feast of new observations that MESSENGER has been sending home on nearly a daily basis,” offers MESSENGER Principal investigator Sean Solomon of the Carnegie Institution of Washington.

A Surface Revealed in Unprecedented Detail

Among the fascinating features seen in MESSENGER flyby images of Mercury were bright, patchy deposits on some crater floors. Without high-resolution images to obtain a closer look, these features remained a curiosity. New targeted Mercury Dual Imaging System images at up to 10 meters per pixel reveal these patchy deposits to be clusters of rimless, irregular pits varying in size from hundreds of meters to several kilometers. These pits are often surrounded by diffuse halos of higher-reflectance material, and they are found associated with central peaks, peak rings, and rims of craters.

"The etched appearance of these landforms is unlike anything we've seen before on Mercury or the Moon,” says Brett Denevi, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and a member of the MESSENGER imaging team. "We are still debating their origin, but they appear to have a relatively young age and may suggest a more abundant than expected volatile component in Mercury's crust.”

Mercury's Surface Composition

The X-ray Spectrometer (XRS) — one of two instruments on MESSENGER designed to measure the abundances of many key elements on Mercury — has made several important discoveries since the orbital mission began. The magnesium/silicon, aluminum/silicon, and calcium/silicon ratios averaged over large areas of the planet's surface show that, unlike the surface of the Moon, Mercury's surface is not dominated by feldspar-rich rocks.

XRS observations have also revealed substantial amounts of sulfur at Mercury's surface, lending support to prior suggestions from ground-based telescopic spectral observations that sulfide minerals are present. This discovery suggests that the original building blocks from which Mercury was assembled may have been less oxidized than those that formed the other terrestrial planets, and it has potentially important implications for understanding the nature of volcanism on Mercury.

Mapping of Mercury's Topography and Magnetic Field

MESSENGER's Mercury Laser Altimeter has been systematically mapping the topography of Mercury's northern hemisphere. After more than two million laser-ranging observations, the planet's large-scale shape and profiles of geological features are both being revealed in high detail. The north polar region of Mercury, for instance, is a broad area of low elevations. The overall range in topographic heights seen to date exceeds 9 kilometers.

Two decades ago, Earth-based radar images showed that around both Mercury's north and south poles are deposits characterized by high radar backscatter. These polar deposits are thought to consist of water ice and perhaps other ices preserved on the cold, permanently shadowed floors of high-latitude impact craters. MESSENGER's altimeter is testing this idea by measuring the floor depths of craters near Mercury's north pole. To date, the depths of craters hosting polar deposits are consistent with the idea that those deposits occupy areas in permanent shadow.

Energetic Particle Events at Mercury

One of the major discoveries made by Mariner 10 during the first of its three flybys of Mercury in 1974 were bursts of energetic particles in Mercury's Earth-like magnetosphere. Four bursts of particles were observed on that flyby, so it was puzzling that no such strong events were detected by MESSENGER during any of its three flybys of the planet in 2008 and 2009. With MESSENGER now in near-polar orbit about Mercury, energetic events are being seen almost like clockwork.

"We are assembling a global overview of the nature and workings of Mercury for the first time,” adds Solomon, "and many of our earlier ideas are being cast aside as new observations lead to new insights. Our primary mission has another three Mercury years to run, and we can expect more surprises as our solar system's innermost planet reveals its long-held secrets."

For more information visit http://www.nasa.gov/mission_pages/messenger/media/NewsConference20110616.html

Firestorm of Star Birth in the Active Galaxy Centaurus A

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Resembling looming rain clouds on a stormy day, dark lanes of dust crisscross the giant elliptical galaxy Centaurus A.

Hubble's panchromatic vision, stretching from ultraviolet through near-infrared wavelengths, reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust.

The warped shape of Centaurus A's disk of gas and dust is evidence for a past collision and merger with another galaxy. The resulting shockwaves cause hydrogen gas clouds to compress, triggering a firestorm of new star formation. These are visible in the red patches in this Hubble close-up.

At a distance of just over 11 million light-years, Centaurus A contains the closest active galactic nucleus to Earth. The center is home for a supermassive black hole that ejects jets of high-speed gas into space, but neither the supermassive or the jets are visible in this image.

This image was taken in July 2010 with Hubble's Wide Field Camera 3.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/galaxy-firestorm.html

NASA Chat: Giant Black Holes in the Early Universe

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Portrayed in movies and on television most often as gateways to another dimension or cosmic vacuum cleaners sucking up everything in sight, the misconceptions surrounding black holes are many and varied. In reality, black holes form when, at the end of their life cycle, heavy stars collapse into a supernova. These relatively puny black holes may provide a "seed" for the development of the giant black holes -- called supermassive -- found at the center of galaxies, which grow by absorbing gas, stars and other black holes.

On Wednesday, June 15, NASA will announce a new discovery about giant black holes in the early universe. This discovery was made using the Chandra X-ray Observatory. Chandra gives astronomers a powerful tool to investigate the universe, especially those hot spots where black holes, exploding stars and colliding galaxies are most likely to live. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes, requiring a space-based telescope to make these observations. Chandra launched in 1999 aboard the Columbia during the STS-93 mission.

Astrophysicists Ezequiel Treister and Kevin Schawinski will be online at 3:00 p.m. EDT on June 15 to answer your questions about the announcement and about black holes in general. Joining the chat is easy. Simply visit this page on Wednesday, June 15, from 3 to 4 p.m. EDT. The chat window will open at the bottom of this page starting about 30 minutes before the chat. You can log in and be ready to ask questions at 3 p.m.

About the Experts

Ezequiel Treister is an astrophysicist for the Institute for Astronomy at the University of Hawaii at Manoa. He has a doctorate in astronomy from the Universidad de Chile, two masters degrees in astronomy from Yale University and a bachelors in physics, also from Universidad de Chile. His interests include active galactic nuclei -- the compact regions at the centers of galaxies with higher than normal luminosity over the electromagnetic spectrum. He studies these nuclei in relation to the cosmic X-ray and Infrared backgrounds of the universe.

Kevin Schawinski is currently an astrophysicist at Yale University in New Haven, Conn. He has a doctorate in astrophysics from the University of Oxford and a bachelors in physics and mathematics from Cornell University. His interests include how galaxies formed and how they co-evolved with the supermassive black holes that lurk at their centers.

For more information visit http://www.nasa.gov/connect/chat/chandra_chat.html

New Insights On How Solar Minimums Affect Earth

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Since 1611, humans have recorded the comings and goings of black spots on the sun. The number of these sunspots wax and wane over approximately an 11-year cycle -- more sunspots generally mean more activity and eruptions on the sun and vice versa. The number of sunspots can change from cycle to cycle and 2008 saw the longest and weakest solar minimum since scientists have been monitoring the sun with space-based instruments.

Observations have shown, however, that magnetic effects on Earth due to the sun, effects that cause the aurora to appear, did not go down in synch with the cycle of low magnetism on the sun. Now, a paper in Annales Geophysicae that appeared on May 16, 2011 reports that these effects on Earth did in fact reach a minimum -- indeed they attained their lowest levels of the century -- but some eight months later. The scientists believe that factors in the speed of the solar wind, and the strength and direction of the magnetic fields embedded within it, helped produce this anomalous low.

"Historically, the solar minimum is defined by sunspot number," says space weather scientist Bruce Tsurutani at NASA's Jet Propulsion Lab in Pasadena, Calif., who is first author on the paper. "Based on that, 2008 was identified as the period of solar minimum. But the geomagnetic effects on Earth reached their minimum quite some time later in 2009. So we decided to look at what caused the geomagnetic minimum."

Geomagnetic effects basically amount to any magnetic changes on Earth due to the sun, and they're measured by magnetometer readings on the surface of the Earth. Such effects are usually harmless, the only obvious sign of their presence being the appearance of auroras near the poles. However, in extreme cases, they can cause power grid failures on Earth or induce dangerous currents in long pipelines, so it is valuable to know how the geomagnetic effects vary with the sun.

Three things help determine how much energy from the sun is transferred to Earth's magnetosphere from the solar wind: the speed of the solar wind, the strength of the magnetic field outside Earth's bounds (known as the interplanetary magnetic field) and which direction it is pointing, since a large southward component is necessary to connect successfully to Earth's magnetosphere and transfer energy. The team -- which also included Walter Gonzalez and Ezequiel Echer of the Brazilian National Institute for Space Research in São José dos Campos, Brazil -- examined each component in turn.

First, the researchers noted that in 2008 and 2009, the interplanetary magnetic field was the lowest it had been in the history of the space age. This was an obvious contribution to the geomagnetic minimum. But since the geomagnetic effects didn't drop in 2008, it could not be the only factor.

To examine the speed of the solar wind, they turned to NASA's Advanced Composition Explorer (ACE), which is in interplanetary space outside the Earth’s magnetosphere, approximately 1 million miles toward the sun. The ACE data showed that the speed of the solar wind stayed high during the sunspot minimum. Only later did it begin a steady decline, correlating to the timing of the decline in geomagnetic effects.

The next step was to understand what caused this decrease. The team found a culprit in something called coronal holes. Coronal holes are darker, colder areas within the sun's outer atmosphere. Fast solar wind shoots out the center of coronal holes at speeds up to 500 miles per second, but wind flowing out of the sides slows down as it expands into space.

"Usually, at solar minimum, the coronal holes are at the sun's poles," says Giuliana de Toma, a solar scientist at the National Center for Atmospheric Research whose research on this topic helped provide insight for this paper. "Therefore, Earth receives wind from only the edges of these holes and it's not very fast. But in 2007 and 2008, the coronal holes were not confined to the poles as normal."

Those coronal holes lingered at low-latitudes to the end of 2008. Consequently, the center of the holes stayed firmly pointed towards wind at Earth begin to slow down. And, of course, the geomagnetic effects and sightings of the aurora along with it.

Coronal holes seem to be responsible for minimizing the southward direction of the interplanetary magnetic field as well. The solar wind's magnetic fields oscillate on the journey from the sun to Earth. These fluctuations are known as Alfvén waves. The wind coming out of the centers of the coronal holes have large fluctuations, meaning that the southward magnetic component – like that in all the directions -- is fairly large. The wind that comes from the edges, however, has smaller fluctuations, and comparably smaller southward components. So, once again, coronal holes at lower latitudes would have a better chance of connecting with Earth's magnetosphere and causing geomagnetic effects, while mid-latitude holes would be less effective.

Working together, these three factors -- low interplanetary magnetic field strength combined with slower solar wind speed and smaller magnetic fluctuations due to coronal hole placement -- create the perfect environment for a geomagnetic minimum.

Knowing what situations cause and suppress intense geomagnetic activity on Earth is a step toward better predicting when such events might happen. To do so well, Tsurutani points out, requires focusing on the tight connection between such effects and the complex physics of the sun. "It's important to understand all of these features better," he says. "To understand what causes low interplanetary magnetic fields and what causes coronal holes in general. This is all part of the solar cycle. And all part of what causes effects on Earth."

For more information visit http://www.nasa.gov/mission_pages/sunearth/news/solar-minima.html

NASA’s Chandra Finds Massive Black Holes Common in Early Universe

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Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe. This discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.

By pointing Chandra at a patch of sky for more than six weeks, astronomers obtained what is known as the Chandra Deep Field South (CDFS). When combined with very deep optical and infrared images from NASA's Hubble Space Telescope, the new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the universe was between about 800 million to 950 million years old.

"Until now, we had no idea what the black holes in these early galaxies were doing, or if they even existed,” said Ezequiel Treister of the University of Hawaii, lead author of the study appearing in the June 16 issue of the journal Nature. “Now we know they are there, and they are growing like gangbusters."

The super-sized growth means that the black holes in the CDFS are less extreme versions of quasars -- very luminous, rare objects powered by material falling onto supermassive black holes. However, the sources in the CDFS are about a hundred times fainter and the black holes are about a thousand times less massive than the ones in quasars.

The observations found that between 30 and 100 percent of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the small observed field to the full sky, there are at least 30 million supermassive black holes in the early universe. This is a factor of 10,000 larger than the estimated number of quasars in the early universe.

“It appears we've found a whole new population of baby black holes,” said co-author Kevin Schawinski of Yale University. “We think these babies will grow by a factor of about a hundred or a thousand, eventually becoming like the giant black holes we see today almost 13 billion years later.”

A population of young black holes in the early universe had been predicted, but not yet observed. Detailed calculations show that the total amount of black hole growth observed by this team is about a hundred times higher than recent estimates.

Because these black holes are nearly all enshrouded in thick clouds of gas and dust, optical telescopes frequently cannot detect them. However, the high energies of X-ray light can penetrate these veils, allowing the black holes inside to be studied.

Physicists studying black holes want to know more how the first supermassive black holes were formed and how they grow. Although evidence for parallel growth of black holes and galaxies has been established at closer distances, the new Chandra results show that this connection starts earlier than previously thought, perhaps right from the origin of both.

“Most astronomers think in the present-day universe, black holes and galaxies are somehow symbiotic in how they grow,” said Priya Natarajan, a co-author from Yale University. “We have shown that this codependent relationship has existed from very early times.”

It has been suggested that early black holes would play an important role in clearing away the cosmic "fog" of neutral, or uncharged, hydrogen that pervaded the early universe when temperatures cooled down after the Big Bang. However, the Chandra study shows that blankets of dust and gas stop ultraviolet radiation generated by the black holes from traveling outwards to perform this “reionization.” Therefore, stars and not growing black holes are likely to have cleared this fog at cosmic dawn.

Chandra is capable of detecting extremely faint objects at vast distances, but these black holes are so obscured that relatively few photons can escape and hence they could not be individually detected. Instead, the team used a technique that relied on Chandra’s ability to accurately determine the direction from which the X-rays came to add up all the X-ray counts near the positions of distant galaxies and find a statistically significant signal.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For more information visit http://www.nasa.gov/mission_pages/chandra/news/H-11-183.html

Nearby Galaxy Boasts Two Monster Black Holes, Both Active

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A study using NASA's Swift satellite and the Chandra X-ray Observatory has found a second supersized black hole at the heart of an unusual nearby galaxy already known to be sporting one.

The galaxy, which is known as Markarian 739 or NGC 3758, lies 425 million light-years away toward the constellation Leo. Only about 11,000 light-years separate the two cores, each of which contains a black hole gorging on infalling gas.

The study will appear in a forthcoming issue of The Astrophysical Journal Letters.

"At the hearts of most large galaxies, including our own Milky Way, lies a supermassive black hole weighing millions of times the sun's mass," said Michael Koss, the study's lead author at NASA's Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland in College Park (UMCP). "Some of them radiate billions of times as much energy as the sun."

Astronomers refer to galaxy centers exhibiting such intense emission as active galactic nuclei (AGN). Yet as common as monster black holes are, only about one percent of them are currently powerful AGN. Binary AGN are rarer still: Markarian 739 is only the second identified within half a billion light-years.

Many scientists think that disruptive events like galaxy collisions trigger AGN to switch on by sending large amounts of gas toward the black hole. As the gas spirals inward, it becomes extremely hot and radiates huge amounts of energy.

Since 2004, the Burst Alert Telescope (BAT) aboard Swift has been mapping high-energy X-ray sources all around the sky. The survey is sensitive to AGN up to 650 million light-years away and has uncovered dozens of previously unrecognized systems. Follow-up studies by Koss and colleagues published in 2010 reveal that about a quarter of the Swift BAT AGN were either interacting or in close pairs, with perhaps 60 percent of them poised to merge in another billion years.

"If two galaxies collide and each possesses a supermassive black hole, there should be times when both black holes switch on as AGN," said coauthor Richard Mushotzky, professor of astronomy at UMCP. "We weren't seeing many double AGN, so we turned to Chandra for help."

Swift's BAT instrument is scanning one-tenth of the sky at any given moment, its X-ray survey growing more sensitive every year as its exposure increases. Where Swift's BAT provided a wide-angle view, the X-ray telescope aboard the Chandra X-ray Observatory acted like a zoom lens and resolved details a hundred times smaller.

For decades, astronomers have known that the eastern nucleus of Markarian 739 contains a black hole that is actively accreting matter and generating prodigious energy. The Chandra study shows that its western neighbor is too. This makes the galaxy one of the nearest and clearest cases of a binary AGN.

The distance separating the two black holes is about a third of the distance separating the solar system from the center of our own galaxy. The dual AGN of Markarian 739 is the second-closest known, both in terms of distance from one another and distance from Earth. However, another galaxy known as NGC 6240 holds both records.

How did the second AGN remain hidden for so long? "Markarian 739 West shows no evidence of being an AGN in visible, ultraviolet and radio observations," said coauthor Sylvain Veilleux, a professor of astronomy at UMCP. "This highlights the critical importance of high-resolution observations at high X-ray energies in locating binary AGN."

The research team also includes Ezequiel Treister and David Sanders at the University of Hawaii’s Institute for Astronomy in Honolulu, Kevin Schawinski at Yale University in New Haven, Conn., and Ranjan Vasudevan, Neal Miller and Margaret Trippe at the University of Maryland, College Park.

Swift, launched in November 2004, is managed by Goddard. It was built and is being operated in collaboration with Penn State University, the Los Alamos National Laboratory in New Mexico, and General Dynamics in Falls Church, Va.; the University of Leicester and Mullard Space Sciences Laboratory in the United Kingdom; Brera Observatory and the Italian Space Agency in Italy; plus additional partners in Germany and Japan.

The Marshall Space Flight Center manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For more information visit http://www.nasa.gov/mission_pages/swift/bursts/monster-black-holes.html

A Big Surprise from the Edge of the Solar System

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NASA's Voyager probes are truly going where no one has gone before. Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news from the most distant, unexplored reaches of the solar system.

Mission scientists say the probes have just sent back some very big news indeed.

It's bubbly out there.

According to computer models, the bubbles are large, about 100 million miles wide, so it would take the speedy probes weeks to cross just one of them. Voyager 1 entered the "foam-zone" around 2007, and Voyager 2 followed about a year later. At first researchers didn't understand what the Voyagers were sensing--but now they have a good idea.

"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."

When a magnetic field gets severely folded like this, interesting things can happen. Lines of magnetic force criss-cross, and "reconnect". (Magnetic reconnection is the same energetic process underlying solar flares.) The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles.

"We never expected to find such a foam at the edge of the solar system, but there it is!" says Opher's colleague, University of Maryland physicist Jim Drake.

Theories dating back to the 1950s had predicted a very different scenario: The distant magnetic field of the sun was supposed to curve around in relatively graceful arcs, eventually folding back to rejoin the sun. The actual bubbles appear to be self-contained and substantially disconnected from the broader solar magnetic field.

Energetic particle sensor readings suggest that the Voyagers are occasionally dipping in and out of the foam—so there might be regions where the old ideas still hold. But there is no question that old models alone cannot explain what the Voyagers have found.

Says Drake: "We are still trying to wrap our minds around the implications of these findings."

The structure of the sun's distant magnetic field—foam vs. no-foam—is of acute scientific importance because it defines how we interact with the rest of the galaxy. Researchers call the region where the Voyagers are now "the heliosheath." It is essentially the border crossing between the Solar System and the rest of the Milky Way. Lots of things try to get across—interstellar clouds, knots of galactic magnetism, cosmic rays and so on. Will these intruders encounter a riot of bubbly magnetism (the new view) or graceful lines of magnetic force leading back to the sun (the old view)?

The case of cosmic rays is illustrative. Galactic cosmic rays are subatomic particles accelerated to near-light speed by distant black holes and supernova explosions. When these microscopic cannonballs try to enter the solar system, they have to fight through the sun's magnetic field to reach the inner planets.

"The magnetic bubbles appear to be our first line of defense against cosmic rays," points out Opher. "We haven't figured out yet if this is a good thing or not."

On one hand, the bubbles would seem to be a very porous shield, allowing many cosmic rays through the gaps. On the other hand, cosmic rays could get trapped inside the bubbles, which would make the froth a very good shield indeed.

So far, much of the evidence for the bubbles comes from the Voyager energetic particle and flow measurements. Proof can also be obtained from the Voyager magnetic field observations and some of this data is also very suggestive. However, because the magnetic field is so weak, the data takes much longer to analyze with the appropriate care. Thus, unraveling the magnetic signatures of bubbles in the Voyager data is ongoing.

"We'll probably discover which is correct as the Voyagers proceed deeper into the froth and learn more about its organization," says Opher. "This is just the beginning, and I predict more surprises ahead."

For more information visit http://www.nasa.gov/mission_pages/voyager/heliosphere-surprise.html

STEREO Sees Complete Far Side

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The far side unveiled! This is the first complete image of the solar far side, the half of the sun invisible from Earth. Captured on June 1, 2011, the composite image was assembled from NASA's two Solar TErrestrial RElations Observatory (STEREO) spacecraft. STEREO-Ahead's data is shown on the left half of image and STEREO-Behind's data on the right.

The STEREO spacecraft reached opposition (180° separation) on February 6 but part of the sun was inaccessible to their combined view until June 1. This image represents the first day when the entire far side could be seen.

The image is aligned so that solar north is directly up. The seam between the two images is inclined because the plane of Earth’s -- and STEREO's -- orbit, known as the "ecliptic", is inclined with respect to the sun's axis of rotation. The data was collected by STEREO's Extreme Ultraviolet Imagers in the SECCHI instrument suites.

STEREO was built and is operated for NASA by the Applied Physical Laboratory of the Johns Hopkins University; the spacecraft were launched on October 25, 2006 aboard a Delta II. The SECCHI instrument suite is a collaboration led by the Naval Research Laboratory, and the EUVI instruments were built by the Lockheed Martin Solar and Astrophysics Laboratory.

For more information visit http://www.nasa.gov/mission_pages/stereo/news/farside-060111.html


  1. Space Station