Posted on by Fraser Cain

Plasma Jets on the Sun Explained

Solar physicists from Lockheed Martin and the Solar Physics and upper-Atmosphere Research Group at the Department of Applied Mathematics of the University of Sheffield, UK have used computer modeling and some of the highest resolution images ever taken of the solar atmosphere to explain the cause of supersonic jets that continuously shoot through the low atmosphere of the Sun.

Their results, which appear as the cover story in tomorrow?s issue of the journal Nature, directly address the origin of these jets, called spicules. The origin of spicules has been a mystery since their discovery in 1877. These findings may well lead to a better understanding of how matter is propelled upward into the solar corona to form the solar wind, a stream of particles continuously emitted by the Sun that sweeps past Earth?s orbit. Disturbances in the solar wind can influence the upper atmosphere and space environment around the Earth and damage satellites in orbit.

?The combination of computer modeling, new high resolution images taken with the Swedish 1-meter Solar Telescope (SST) on the island of La Palma, Spain and data taken simultaneously with two satellites in space, was crucial to figure out how spicules are formed,? said Dr. Bart De Pontieu, one of the main investigators on the study, and solar physicist at the Lockheed Martin Solar and Astrophysics Lab (LMSAL) at the company?s Advanced Technology Center in Palo Alto, Calif. ?We used a computer model to provide the missing link between observations of the surface of the Sun, taken with the MDI instrument onboard ESA/NASA?s Solar and Heliospheric Observatory (SOHO) satellite, and observations of the jets in the low solar atmosphere taken with the SST and NASA?s Transition Region and Coronal Explorer (TRACE) satellite.?

Spicules are jets of gas or plasma propelled upwards from the surface of the Sun. They shoot into its atmosphere or corona at supersonic speeds of about 50,000 miles per hour, and reach heights of 3,000 miles above the solar surface in less than five minutes. Although there are over 100,000 spicules at any time in the Sun?s low atmosphere, or chromosphere, they remain largely unexplained, in part because observations are difficult for objects with so brief a lifetime (about five minutes) and relatively small size (300 miles diameter).

?By simultaneously taking a series of high resolution images with the Swedish Solar Telescope, showing details down to 80 miles, and with the TRACE satellite, we discovered that these jets often occur periodically, usually every five minutes or so, at the same location,? said Professor Robertus Erd?lyi von F?y-Siebenb?rgen, the other main investigator on the study, and professor in applied mathematics at the Solar Physics and upper-Atmosphere Research Group of the University of Sheffield, UK. ?We developed a computer model of the Sun?s atmosphere to show that the periodicity of the spicules is caused by sound waves at the solar surface that have the same five minute period.?

The sound waves at the solar surface are usually damped before they can reach the Sun?s atmosphere. However, De Pontieu, Erd?lyi and Stewart James, a newly graduated Ph.D. under the supervision of Professor Erd?lyi at the University of Sheffield, found that under certain conditions, the sound waves can penetrate through the damping zone and leak into the solar atmosphere. Their computer model shows that after the sound waves leak into the atmosphere, they develop into shock waves that propel matter upwards, forming a spicule.

De Pontieu and his colleagues measured actual waves and oscillations at the surface of the Sun, using these measurements to drive their computer model of the solar atmosphere, which then predicted when jets of gas should shoot up. They were pleasantly surprised to see that the model predicts very accurately when jets should be observed on the Sun with the SST and TRACE.

?Spicules carry more than 100 times the mass into the Sun?s atmosphere required to feed the solar wind,? said De Pontieu, ?which means that they are of huge importance for the balance of how much mass goes into and out of the corona.? With the origins of spicules revealed, it will be possible to study whether the mass that spicules carry into the solar corona contributes to the solar wind. Future studies will also focus on the role the shock waves may play in the higher solar atmosphere or corona.

The results of this study are in a paper published in the journal Nature. The authors are Dr. Bart De Pontieu of Lockheed Martin Solar and Astrophysics Lab, and Professor Robertus Erd?lyi von F?y-Siebenb?rgen and Dr. Stewart James of The Solar Physics and upper-Atmosphere Research Group at the Department of Applied Mathematics, University of Sheffield, UK. Funding for the studies came from NASA, the Particle Physics and Astronomy Research Council of the UK and the Hungarian National Science Foundation.

The Lockheed Martin Solar and Astrophysics Lab is part of Lockheed Martin?s Advanced Technology Center ? the research and development organization of Lockheed Martin Space Systems Company. Headquartered in Bethesda, Md., Lockheed Martin employs about 130,000 people worldwide and is principally engaged in the research, design, development, manufacture and integration of advanced technology systems, products and services. The corporation reported 2003 sales of $31.8 billion.

Original Source: LMSAL News Release

Posted on by Fraser Cain

Swift Moves to Florida to Prepare for Launch

The Swift satellite, which will pinpoint the location of distant yet fleeting explosions that appear to signal the births of black holes, arrived at Kennedy Space Center today in preparation for an October launch.

These enigmatic flashes, called gamma-ray bursts, are the most powerful explosions known in the Universe, emitting more than one hundred billion times the energy than the Sun does in an entire year. Yet they last only a few milliseconds to a few minutes, never to appear in the same spot again.

The Swift satellite is named for the nimble bird, because it can swiftly turn and point its instruments to catch a burst “on the fly” to study both the burst and its afterglow. The afterglow phenomenon follows the initial gamma-ray flash in most bursts; and it can linger in X-ray light, optical light and radio waves for hours to weeks, providing great detail.

“Gamma-ray bursts have ranked among the biggest mysteries in astronomy since their discovery over 35 years ago,” said Dr. Neil Gehrels, Swift Lead Scientist from NASA’s Goddard Space Flight Center in Greenbelt, Md. “Swift is just the right tool needed to solve this mystery. One of Swift’s instruments will detect the burst, while, within a minute, two higher-resolution telescopes will be swung around for an in-depth look. Meanwhile, Swift will ‘e-mail’ scientists and telescopes around the world to observe the burst in real-time.”

The Burst Alert Telescope (BAT) instrument, built by NASA Goddard, will detect and locate about two gamma-ray bursts per week, relaying a 1- to 4-arc-minute position to the ground within about 20 seconds. This position will then be used to “swiftly” re-point the satellite to bring the burst area into the narrower fields of view to study the afterglow with the X-ray Telescope (XRT) and the
UltraViolet/Optical Telescope (UVOT).

These two longer-wavelength (lower-energy) instruments will determine an arc-second position of a burst and the spectrum of its afterglow at visible to x-ray wavelengths. For most of the bursts detected with Swift this data, together with observations conducted with ground-based telescopes, will enable measurement of the redshift, or distance, to the burst source. The afterglow provides crucial information about the dynamics of the burst, but scientists need precise information about the burst in order to locate the afterglow.

Swift notifies the community — which includes museums and the general public, along with scientists at world-class observatories — via the Goddard-maintained Gamma-ray Burst Coordinates Network (GCN). A network of dedicated ground-based robotic telescopes distributed around the world await Swift-GCN alerts.

Continuous burst information flows through the Swift Mission Operations Center, located at Penn State. Penn State, a key U.S. collaborator, built the XRT with University of Leicester (UK) and the Astronomical Observatory of Brera (Italy) and the UVOT with Mullard Space Science Lab (UK).

In addition to providing new clues to the nature of the burst mechanism, Swift’s detection of gamma-ray bursts could provide a bonanza of cosmological data.

“Some bursts likely originate from the farthest reaches, and hence earliest epoch, of the Universe,” said Swift Mission Director John Nousek, professor of astronomy and astrophysics at Penn State. “They act like beacons shining through everything along their paths, including the gas between and within galaxies along the line of sight.”

Theorists have suggested that some bursts may originate from the first generation of stars, and Swift’s unprecedented sensitivity will provide the first opportunity to test this hypothesis.

With NASA’s High-Energy Transient Explorer (HETE-2), now in operation, scientists have determined that at least some bursts involve the explosions of massive stars. Swift will fine-tune this knowledge — that is, answer such questions as how massive, how far, what kind of host galaxies, and why are some bursts so different from others?

While the link between some fraction of bursts with the death of massive stars appears firm, others may signal the merger of neutron stars or black holes orbiting each other in exotic binary star systems. Swift will determine whether there are different classes of gamma-ray bursts associated with a particular origin scenario. Swift may be fast enough to identify afterglows from short bursts, if they exist. Afterglows have only been seen for bursts lasting longer than two seconds. “We may be seeing only half the story so far,” said Gehrels.

The Swift team expects to detect and analyze over 100 bursts a year. When not catching gamma-ray bursts, Swift will conduct an all-sky survey at high-energy “hard” X-ray wavelengths, which will be 20 times more sensitive than previous measurements. Scientists expect that Swift’s enhanced sensitivity relative to earlier surveys will uncover over 400 new supermassive black holes.

Swift, a medium-class explorer mission, is managed by NASA’s Goddard Space Flight Center in Greenbelt, Md., Swift was built in collaboration with national laboratories, universities, and international partners, including the Los Alamos National Laboratory, Penn State University, Sonoma State University, Italy, and the United Kingdom.

Original Source: NASA News Release

Posted on by Fraser Cain

Quintuplet Cluster Imaged by Chandra

This Chandra image presents the first detection of X-rays from stars in the Quintuplet Cluster, an extremely dense young star cluster near the Galactic Center. Because dust blocks visible light from the Galactic Center, the cluster was not discovered until 1990 when it was detected with an infrared telescope. Named for its five brightest stars at infrared wavelengths, the Quintuplet is known to be home to hundreds of stars. Several of these are very massive stars that are rapidly losing gas from their surfaces in high-speed stellar winds.

The bright point-like concentrations of 50 million degree Celsius gas in Chandra’s image are thought to be caused by collisions between the high-speed winds in massive stars that have closely orbiting partners. Colliding stellar winds could also explain the diffuse X-radiation seen between the stars in the Quintuplet. The detection of radio waves from hot gas in this region provides further evidence for vigorous heating of gas by winds from massive stars.

Original Source: Chandra News Release

Posted on by Fraser Cain

Young Stars Thrown Out of the Nursery

Astronomers studying data from the National Science Foundation’s Very Long Baseline Array (VLBA) and other telescopes have concluded that a binary pair of stars forming an energetic microquasar was blasted out of the cluster in which it was born by a supernova explosion some 1.7 million years ago. This is the first time that a fast-moving stellar pair has been tracked back to a specific star cluster.

The scientists analyzed numerous observations of a microquasar called LSI +61 303, and concluded that it is moving away from a star cluster named IC 1805 at nearly 17 miles per second.

A microquasar is a pair of stars, one of which is either a dense neutron star or a black hole, in which material sucked from a “normal” star forms a rapidly-rotating disk around the denser object. The disk becomes so hot it emits X-rays, and also spits out “jets” of subatomic particles at nearly the speed of light.

“In this case, both the microquasar and the star cluster are about 7,500 light-years from Earth and the characteristics of the ‘normal’ star in the microquasar match those of the other stars in the cluster, so we feel confident that the microquasar was shot out from a birthplace in this cluster,” said Felix Mirabel, an astrophysicist at the Institute for Astronomy and Space Physics of Argentina and French Atomic Energy Commission. Mirabel worked with Irapuan Rodrigues, of the Federal University of Rio Grande do Sul, Brazil, and Qingzhong Liu of the Purple Mountain Observatory in Nanjing, China. The astronomers reported their results in the August 1 issue of the scientific journal Astronomy & Astrophysics.

Many neutron stars have been found to be moving rapidly through the sky, leading scientists to conclude that the supernova explosions that produced them were asymmetric, giving a “kick” to the star. LSI +61 303’s motion has carried it about 130 light-years from the cluster IC 1805. The cluster is in the constellation Cassiopeia.

LSI +61 303 contains, the astronomers say, either a black hole or a neutron star with twice the mass of the Sun, orbiting a normal star 14 times more massive than the Sun every 26.5 days. The supernova explosion that produced the black hole or neutron star blew away about twice the mass of the Sun.

The black hole or neutron star originally was much more massive than its companion. The scientists still are unsure about how massive it was. Some evidence, they say, indicates that it was formed only four or five million years ago and exploded a million or so years ago. In that case, the star would have been 60 or more times more massive than the Sun, and would have expelled some 90 percent of its initial mass before the supernova explosion.

On the other hand, they say, the star may have formed some 10 million years ago, in which case it would have been 15-20 times more massive than the Sun.

“Studying this system and hopefully others like it that may be found will help us to understand both the evolution of stars before they explode as supernovae and the physics of the supernova explosions themselves,” Mirabel said.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Original Source: NRAO News Release

Posted on by Fraser Cain

The Race is On for the X Prize

The X PRIZE Foundation announced key next steps today by two of its top competitors for the ANSARI X PRIZE. The American Mojave Aerospace Ventures, LLC Team (a partnership between Paul G. Allen and Burt Rutan and his team at Scaled Composites) announced today that it has given its official 60-day notice and has scheduled its first competition flight on September 29th, 2004, at the Mojave Airport Civilian Aerospace Test Center in Mojave, California. To win the $10 million, SpaceShipOne will need to make a second flight within two weeks, by October 13th, 2004.

In addition, the Canadian da Vinci Project Team, based in Toronto, Canada, announced its plans to roll-out its completed Wild Fire spacecraft for public viewing and photo opportunities on Thursday, Aug 5th, 2004, at its Downsview Airport hanger in Toronto. The da Vinci Project Team, widely heralded as a contender for the $10 million, will pursue its own ANSARI X PRIZE space flight attempts this Fall.

Also introduced to supporters and press was Amir Ansari, representing the Ansari family, the benefactors who titled the ANSARI X PRIZE, and Astronaut Rick Searfoss, the Chief Judge of the competition. The announcements took place at the Santa Monica Municipal Airport in Santa Monica, California, at 10:30 am PST.

“Eight years ago, under the Arch in St. Louis, we kicked off the X PRIZE competition. Today I’m pleased to announce that the first team is ready to make an attempt to claim the $10 million, with other teams close behind, said Dr. Peter H. Diamandis, Chairman and Founder of the X PRIZE Foundation. “The American Mojave Aerospace Ventures Team and the Canadian da Vinci Project Team are just two of the 26 competing groups who will someday make it possible for spaceflights to be conducted from commercial spaceports across the globe. When the ANSARI X PRIZE competition is won, it will herald the start of a new renaissance of spaceflight in which the general public will have their chance to fly next.”

If successful, Mojave Aerospace Ventures will make history by launching a privately financed, manned spaceship to 100 km altitude, twice within two weeks, each carrying a pilot and the weight and volume equivalent of two additional passengers. On June 21st, Mike Melvill, a pilot for Mojave Aerospace Ventures, became the first commercial pilot to enter suborbital space, earning astronaut wings and a spot in the Guinness Book of World Records. Similar to the June flight, the competition launches will take place at the Mojave Airport Civilian Aerospace Test Center in Mojave, California. The public is invited and encouraged to attend the historic events. Parking passes for public attendance can be purchased on the X PRIZE website (www.xprize.org).

“The idea of competitions have always had a rich heritage in our society,” said Paul G. Allen, sole investor of SpaceShipOne and partner in Mojave Aerospace Ventures, LLC. “This competition has proven that there are many different ways to attack the challenges set out by the ANSARI X PRIZE. From the start we have approached SpaceShipOne with a ‘can-do, home-brew’ attitude. We are grateful that our previous flights have brought even more attention to the ANSARI X PRIZE and given more momentum to the groundswell of excitement that is continuing to build for the long-term potential of affordable space exploration.”

“I want to thank the X PRIZE Foundation for providing the inspiration in 1996, to get us little guys thinking about private development of manned space flight. Last month our team demonstrated that private companies can indeed conduct space flights without government help.” stated Burt Rutan, Team Leader of the Mojave Aerospace Ventures Team and designer of both the White Knight and SpaceShipOne. “We are hopeful to complete both qualifying flights and to win the ANSARI X PRIZE.”

Wild Fire, the Canadian da Vinci Project Team spacecraft, is also launched at high-altitude into suborbital space at 80,000 feet from an unmanned, reusable helium balloon. The Canadian da Vinci Project Team, considered one of the top ANSARI X PRIZE competitors, will reveal its Wild Fire space vehicle to the public for the first time on August 5th, 2004, at its Downsview Airport Hanger in Toronto.

“The da Vinci Project Team has made huge strides in the past year and we’re excited to finally share Wild Fire with the public,” noted Brian Feeney, da Vinci Project Team Leader. “We’re in the commercial tourist race for the long haul and while working with an all-volunteer team, we’ve been able to accomplish major aviation and space milestones in pursuit of the ANSARI X PRIZE.”

In addition, Colonel Rick Searfoss, pilot and commander of three Space Shuttle missions, was introduced as the Chief Judge of the ANSARI X PRIZE. “We have met with the Mojave Aerospace Ventures Team and we are prepared to ensure that the flights are well monitored and that all rules are followed carefully,” said Col. Searfoss. “As an experienced astronaut, I can tell you that I’m personally excited to see the beginning of a new generation of spaceflight.”

About the ANSARI X PRIZE Competition
Currently, 26 teams from around the globe are competing for the $10 million ANSARI X PRIZE. In order to win the competition, teams must build a safe and reusable space vehicle able to carry one pilot and the weight equivalent of two passengers, 100km (62 miles) into suborbital space. The vehicle must be privately financed and safely flown twice within a two-week period. The first registered ANSARI X PRIZE team to complete this feat will win the $10 million prize and a spectacular 5-foot trophy.

About the X PRIZE Foundation (www.xprize.org)
The X PRIZE Foundation is a not-for-profit educational organization with headquarters in St. Louis, Missouri. The Foundation’s ANSARI X PRIZE Competition is supported by its Title Sponsor, the Ansari family, and Presenting Sponsor, Champ Car World Series. The Foundation is also supported by private donations from the St. Louis Community through an organization called the New Spirit of St. Louis Organization. The Foundation’s mission is to educate the public about space travel, create educational programming for students and space enthusiasts, and provide incentives in the private sector to make space travel frequent and affordable for the general public. Several additional sponsorships for the ANSARI X PRIZE competition remain available to corporations or individuals who wish to support the contest and associate themselves with courage, determination, achievement, space, speed, high performance and technology.

To find out how individuals or corporations can join the efforts of the X PRIZE, or involve neighborhood schools or community centers with X PRIZE educational programs, visit www.xprize.org or contact the office at 636-519-9449

Original Source: X Prize News Release

Posted on by Fraser Cain

Key Part Redesigned for Shuttle’s Return to Flight

NASA is moving ahead with plans to redesign a part of the Space Shuttle external fuel tank that investigators believe played a critical role in the Space Shuttle Columbia accident. The Space Shuttle program will soon begin manufacturing and installing an improved bipod fitting, which connects the external fuel tank to the Shuttle during launch.

A Critical Design Review Board of NASA managers, engineers and aerospace contractors last month approved the new design, a significant milestone in the effort to return the Shuttle to safe flight. The approval allows workers to begin incorporating the new fitting on External Tank No. 120, the tank slated for flight on the next Shuttle mission, designated STS-114.

Investigators believe that during Columbia’s launch in January 2003, insulating foam from the bipod area fell off the external tank and damaged the left wing of the Space Shuttle. The new design addresses the Columbia Accident Investigation Board recommendation to reduce the risk to the Shuttle from falling debris during liftoff. It eliminates the foam covering from the bipod fitting and replaces it with four rod-shaped heaters. The heaters will serve the same primary function as the foam, preventing ice buildup on the tank’s bipod fittings.

“This is a fix that really gets to the root of the technical problems that caused the loss of Columbia,” said Michael Kostelnik, NASA’s Deputy Associate Administrator for International Space Station and Space Shuttle Programs. “By eliminating this debris source, as well as potential debris from other areas, we are making the Shuttle a safer spacecraft.”

The External Tank Project Office at NASA’s Marshall Space Flight Center, Huntsville, Ala., first began developing redesign concepts for the bipod fitting after insulating foam from the left bipod ramp area detached during the October 2002 launch of Space Shuttle Atlantis.

The newly designed heaters will be placed below the fitting, in covers made of a strong alloy composed of nickel, chromium and iron. They will sit on top of a copper plate sandwiched between the fitting and a hard, dense material that separates the heater from the tank.

The design will be retrofitted on the 11 existing tanks and incorporated into the manufacture of all new tanks. Lockheed Martin Space Systems will do the work at NASA’s Michoud Assembly Facility in New Orleans. Delivery of the retrofitted tanks to NASA’s Kennedy Space Center, Florida, is expected in October.

For still photos on the Internet of the redesigned bipod fitting, visit:

http://www.nasa.gov/returntoflight

Video b-roll of the new bipod will air on NASA Television during the Video File segment starting at noon EDT today. Beginning July 24, NASA Television will be seen in the continental United States on AMC-6, at 72 degrees west longitude, Transponder 9, 3880 MHz, vertical polarization, audio at 6.8 MHz. If you live in Alaska or Hawaii, NASA TV will now be seen on AMC-7, at 137 degrees west longitude, Transponder 18, at 4060 MHz, vertical polarization, audio at 6.8 MHz.

For information about NASA TV, visit:

http://www.nasa.gov/ntv

More information on NASA’s human space flight programs is available at:

http://www.nasa.gov

Original Source: NASA News Release

Posted on by Fraser Cain

Crescent Titan

Following its first flyby of Titan, Cassini gazed back at the smog-enshrouded moon?s receding crescent. This natural color view was seen by the spacecraft about one day after closest approach. The slight bluish purpose glow of Titan?s haze is visible along the limb.

The superimposed coordinate system grid in the accompanying image at right illustrates the geographical regions of the moon that are illuminated and visible, as well as the orientation of Titan ? lines of longitude converge on the South Pole near the moon?s eastern limb. The yellow curve marks the position of the boundary between day and night on Titan.

Images taken through blue, green and red filters were combined to create this natural color view. The image were obtained using the wide angle camera on July 3, 2004, from a distance of about 790,000 kilometers (491,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 115 degrees. The image scale is 47 kilometers (29 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

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

Original Source: CICLOPS News Release

Posted on by Fraser Cain

Neutrino Mass Linked to Dark Energy

Two of the biggest physics breakthroughs during the last decade are the discovery that wispy subatomic particles called neutrinos actually have a small amount of mass and the detection that the expansion of the universe is actually picking up speed.

Now three University of Washington physicists are suggesting the two discoveries are integrally linked through one of the strangest features of the universe, dark energy, a linkage they say could be caused by a previously unrecognized subatomic particle they call the “acceleron.”

Dark energy was negligible in the early universe, but now it accounts for about 70 percent of the cosmos. Understanding the phenomenon could help to explain why someday, long in the future, the universe will expand so much that no other stars or galaxies will be visible in our night sky, and ultimately it could help scientists discern whether expansion of the universe will go on indefinitely.

In this new theory, neutrinos are influenced by a new force resulting from their interactions with accelerons. Dark energy results as the universe tries to pull neutrinos apart, yielding a tension like that in stretched rubber band, said Ann Nelson, a UW physics professor. That tension fuels the expansion of the universe, she said.

Neutrinos are created by the trillions in the nuclear furnaces of stars such as our sun. They stream through the universe, and billions pass through all matter, including people, every second. Besides a minuscule mass, they have no electrical charge, which means they interact very little, if at all, with the materials they pass through.

But the interaction between accelerons and other matter is even weaker, Nelson said, which is why those particles have not yet been seen by sophisticated detectors. However, in the new theory, accelerons exhibit a force that can influence neutrinos, a force she believes can be detected by a variety of neutrino experiments already operating around the world.

“There are many models of dark energy, but the tests are mostly limited to cosmology, in particular measuring the rate of expansion of the universe. Because this involves observing very distant objects, it is very difficult to make such a measurement precisely,” Nelson said.

“This is the only model that gives us some meaningful way to do experiments on earth to find the force that gives rise to dark energy. We can do this using existing neutrino experiments.”

The new theory is advanced in a paper by Nelson; David Kaplan, also a UW physics professor; and Neal Weiner, a UW research associate in physics. Their work, supported in part by a grant from the U.S. Department of Energy, is detailed in a paper accepted for publication in an upcoming issue of Physical Review Letters, a journal of the American Physical Society.

The researchers say a neutrino’s mass can actually change according to the environment through which it is passing, in the same way the appearance of light changes depending on whether it’s traveling through air, water or a prism. That means that neutrino detectors can come up with somewhat different findings depending on where they are and what surrounds them.

But if neutrinos are a component of dark energy, that suggests the existence of a force that would reconcile anomalies among the various experiments, Nelson said. The existence of that force, made up of both neutrinos and accelerons, will continue to fuel the expansion of the universe, she said.

Physicists have pursued evidence that could tell whether the universe will continue to expand indefinitely or come to an abrupt halt and collapse on itself in a so-called “big crunch.” While the new theory doesn’t prescribe a “big crunch,” Nelson said, it does mean that at some point the expansion will stop getting faster.

“In our theory, eventually the neutrinos would get too far apart and become too massive to be influenced by the effect of dark energy any more, so the acceleration of the expansion would have to stop,” she said. “The universe could continue to expand, but at an ever-decreasing rate.”

Original Source: University of Washington News Release

Posted on by Fraser Cain

Astronauts Prepare for Third Spacewalk

The International Space Station’s Expedition 9 crewmembers are now past the halfway point of their six-month mission. This week, they prepared for a third spacewalk and joined the world in observing the 35th anniversary of the first landing of humans on the moon.

July 19 was the midpoint of the flight for ISS Commander Gennady Padalka and Flight Engineer Mike Fincke, who launched Apr. 19 and are targeted to return Oct. 19. On Monday Fincke spoke with Charles Gibson of ABC-TV’s “Good Morning, America” about the birth of his daughter, Tarali, in June while he was in space. Fincke’s wife and children joined the discussion from Houston.

This week the crew continued packing unneeded equipment and trash in the Progress vehicle, scheduled to undock July 30. Undocking the Progress from Zvezda’s aft docking port will clear the area for the next spacewalk, targeted for Aug. 3. Wearing Russian spacesuits and exiting from the Pirs Docking Compartment, Padalka and Fincke are to install retroreflectors and communications equipment needed for the docking of the Automated Transfer Vehicle, a European Space Agency cargo spacecraft scheduled to make its first flight next year. Yesterday, Padalka and Fincke maneuvered the Station’s Canadarm2 into position so its cameras can view the spacewalk, and today they wrapped up a thorough review of the spacewalk timeline with specialists in Moscow.

Fincke and Padalka also continued their support this week of an experiment that looks at the interactions between the crew and the ground teams. This experiment involves a questionnaire on a laptop computer, which the crew and members of their ground support team complete once a week. The data is being used to examine issues involving tension, cohesion and leadership roles in both the crewmembers and their support team. The information gained will lead to improved training and in-flight support of future space crews.

As part of Fincke’s Saturday Afternoon Science, he conducted another session of the Educational Payload Operations or EPO. This EPO activity demonstrated what crewmembers can observe about pollution and the environmental problems on Earth. Fincke showed the window where he observes the Earth, and described what types of pollution can be seen — such as air pollution in urban areas, smoke from wildfires, deforestation and strip mining.

The activity was videotaped and will be used later in classrooms and NASA educational products. EPO is an education payload designed to support the NASA Mission to inspire the next generation of explorers.

Meanwhile, flight controllers in Houston are continuing to investigate why two U.S. spacesuits are not providing the proper cooling. This week, Fincke conducted troubleshooting of a motor in the water pump of one of the spacesuits as engineers on the ground monitored. An analysis of photos and video from that work is underway. Two spare water pumps will be launched in the next Progress supply ship, due to lift off Aug. 11 from the Baikonur Cosmodrome in Kazakhstan.

The failure of a computer on the Station’s inactive starboard thermal radiator on Monday has no significant impact on current operations. The radiator is not in use in the present Station configuration, although the computer had assisted flight controllers with monitoring of temperatures and pressures of the unused equipment. The radiator is not scheduled to be used until several missions after the Space Shuttle’s return to flight.

Tuesday, Padalka and Fincke celebrated the anniversary of the Apollo 11 moon landing and discussed the past, present and future of space exploration — and the role to be played by the International Space Station in future exploration — during in an interview with CBS News.

For information about NASA and agency missions on the Internet, visit:

http://www.nasa.gov

Information about crew activities on the Space Station, future launch dates and Station sighting opportunities from Earth, is available on the Internet at:

http://spaceflight.nasa.gov/

Details about Station science operations are available on an Internet site administered by the Payload Operations Center at NASA’s Marshall Space Flight Center in Huntsville, Ala., at:

http://scipoc.msfc.nasa.gov/

Original Source: NASA News Release

Posted on by Fraser Cain

Some of the Hazards in Space

Space is one of the most extreme environments imaginable. Above the insulating atmosphere of the Earth, spacecraft are subjected to extremes of temperature, both hot and cold, and a significantly increased threat of radiation damage.

The first extreme condition a spacecraft has to deal with is that of launch. The rocket that places the spacecraft into orbit will also shake it violently and batter it with extremely loud sound waves.

Either of these phenomena can shatter delicate pieces of equipment and so engineers always build a thermal and structural model of the spacecraft and test it. They simulate the conditions of launch using the vibration table and acoustic chamber at ESA’s European Space Technology Centre (ESTEC) in The Netherlands.

Temperatures in space can range from the extremely cold, hundreds of degrees below freezing, to many hundreds of degrees above ? especially if a spacecraft ventures close to the Sun.

Although there is no air in space, energy is carried by radiation, usually coming from the Sun, that causes heating when it is absorbed by spacecraft, planets or other celestial bodies.

Depending on where in space they intend a vehicle to operate, engineers build in either cooling systems or insulators.

However, in the case of ESA’s comet-chaser Rosetta, the spacecraft must first venture into the heat of the inner Solar System, before heading away into the freezing outer Solar System.

Engineers designed a system of ‘louvres’ that fit over the spacecraft’s radiator panels. When Rosetta is in the inner Solar System, the louvres swing open, allowing the radiators to expel excess heat into space.

Later, in the outer Solar System, the louvres shut, helping to retain heat inside. Ensuring that integrated circuits and computers can work in the radiation environment of space requires the shielding of sensitive electronic equipment.

Radiation in space can be split into ‘trapped’ and ‘transient’ types. The trapped particles are the subatomic particles, mainly protons and electrons, trapped by Earth’s magnetic field which creates the so-called Van Allen radiation belts around our planet.

The Cluster quartet of spacecraft are designed to work in and investigate this region of space.

The transient radiation is mainly composed of protons and cosmic rays that constantly stream through space and are enhanced during the magnetic storms on the Sun known as ‘solar flares’.

When this radiation collides with electronic circuits, they can change the contents of memory cells, cause spurious currents to flow around the craft or even burn out computer chips.

Building integrated circuits that resist the effects of radiation is known as ‘space hardening’. Usually this involves redesigning the chips so that they are shielded in some way from the harmful radiation. Another approach is to detect the errors produced by space radiation and correct them.

Meteor showers can also damage spacecraft. The little dust particles that cause us to see ‘shooting stars’ travel through space at several kilometres per second and can have the effect of ‘sand blasting’ large arrays of vital solar panels.

During a storm of the Leonids, for example, scientists made the Hubble Space Telescope turn so that its solar panels presented the smallest surface area to the incoming meteors.

Original Source: ESA News Release