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

Posted on by Fraser Cain

Fractured Crater on Mars

This perspective image of a fractured crater near Valles Marineris on Mars was obtained by the High Resolution Stereo Camera (HRSC) on board the ESA Mars Express spacecraft.

The image was taken during orbit 61 in January 2004 with a resolution of 12. 5 metres per pixel. It shows part of a cratered landscape to the north of the Valles Marineris, at 0.6? S latitude and 309? E longitude, with this crater having a fractured base.

This crater has a rim diameter of 27.5 kilometres and is about 800 metres deep. It is not known yet how these fractures are generated. On Earth, polygonal fractures may occur in contracting material, which breaks at weak zones. For example, we may see this appearing in cooled lava, dried clay or frozen ground.

Original Source: ESA News Release

Posted on by Fraser Cain

Closer to Titan

About a day after entering orbit around Saturn, Cassini sped silently past Titan, passing some 339,000 kilometers (210,600 miles) above the moon?s south polar region. This natural color image represents Cassini?s view only about two hours after closest approach to the moon.

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 above center in the image. 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 images were obtained using the wide angle camera on July 2, 2004, from a distance of about 347,000 kilometers (216,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 62 degrees. This view is an improvement in resolution of nearly a factor of four over the previously released natural color view of Titan (PIA 06081). The image scale is 21 kilometers (13 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

SMART-1’s View of the Middle East

Now more than 100 000 kilometres away from Earth, ESA’s Moon-bound spacecraft SMART-1 looked back at Earth and returned this planetary perspective of the Middle East and Mediterranean Sea.

‘Smart’ usage of the solar-electric propulsion system (the ion engine) has saved a lot of fuel and the spacecraft will get to the Moon earlier than expected.

Almost 20 kilograms of the xenon fuel could be saved out of the original 84 kilograms, which could then be used to get closer to the Moon than planned, to within distances of between 300 and 3000 kilometres. This will give a coverage of the lunar surface at higher resolution and sensitivity.

Original Source: ESA News Release

Posted on by Fraser Cain

Get Ready for the Perseids

Image credit: ESA
The annual Perseid meteor shower is coming, and astronomers say it could be unusually good this year.

The shower begins gently in mid-July when Earth enters the edge of a cloud of debris from Comet Swift-Tuttle.

Dust-sized particles will hit our atmosphere and appear to streak across the night sky. At first there will be just a few meteors each night, but then the rate will build. The Perseids are visible between 23 July and 22 August but, by 12 August, at the peak of the shower, skywatchers can expect to see possibly 80-100 meteors per hour if skies are clear.

This is a good year for Perseids for two reasons. First, the Moon is new in mid-August, so moonlight will not spoil the show as much as it would have done last year, had the sky been clear! Second, in addition to the usual shower on 12 August, there might be an extra show of meteors late in the evening of 11 August caused by a ?filament? of dust drifting across Earth’s orbit for the first time.

This filament, like all the dust in the Perseid cloud, again comes from Comet Swift-Tuttle. The difference is, the filament is relatively young. It ?boiled? off the comet in 1862. Other dust in the cloud is older (perhaps thousands of years old), more dispersed, and responsible for the month-long shower that peaks on 12 August. The filament will eventually disperse, too, but for now it retains some of its original ribbon shape.

According to current predictions, Earth will move through the filament on Wednesday, 11 August at 23:00 CEST. This will produce a surge of mostly faint meteors over Europe and Asia. Because of the way Comet Swift-Tuttle?s orbit is tilted, its dust falls on Earth’s northern hemisphere. Meteors appear to stream out of the constellation Perseus, which is barely visible south of the equator.

Later that night and into the early morning hours of Thursday, 12 August, observers will see the ?traditional? Perseid peak caused by the older dust from Swift-Tuttle. The best time to look for these traditional Perseids is during the hours before dawn on Thursday.

How to observe the Perseids
The best way to observe them is to look towards the northeast after dark. They appear to originate from the constellation of Perseus which at midnight lies just below the easily recognisable ‘W’ of Cassiopeia.

Try looking around 22:00-23:00 CEST on Wednesday, when Perseus is hanging low in the eastern sky. You won’t see many meteors then, but the ones you do see could be memorable. On Thursday morning, the highest frequency of meteors is likely just before dawn.

Original Source: ESA News Release

Posted on by Fraser Cain

China Launches Second Double Star

Yesterday, 25 July at 09:05 CEST (15:05 local time) the Chinese National Space Administration successfully launched Tan Ce 2, the second of the Double Star science satellites. This marks the latest important milestone in the scientific collaboration between China and the European Space Agency.

Tan Ce (“Explorer”) 2 was launched from the Taiyuan spaceport west of Beijing (Zhangye province) using a Long March 2C rocket. The launch, initially scheduled for today 26 July, took place one day earlier in order to avoid adverse weather conditions expected in the days to come. The spacecraft will join Tan Ce 1, which was launched on 29 December 2003, to complete the Double Star configuration.

About 8 hours after launch the two solid booms holding the magnetometers were successfully deployed. In the next few weeks, all spacecraft sub-systems will be checked out and the commissioning of the on-board scientific instrument will follow.

Double Star will operate alongside ESA?s quartet of Cluster satellites to closely study the interaction between the solar wind and the Earth?s magnetic field. Together, these missions will provide the most detailed view to date. TC-1 is already returning a wealth of scientific data. Back in January, both missions tracked a coronal mass ejection from the Sun and gathered valuable data about the Earth’s bow shock.

Tan Ce 2 reached its nominal orbit, with perigee at 682 km, apogee at 38279 km and inclination of 90.1 deg. The positions and orbit of the Double Star satellites have been carefully defined to enable exploration of the magnetosphere on a larger scale than is possible with Cluster alone. One example of this coordinated activity is the study of the substorms that produce aurorae.

The exact region where these emissions of brightness form is still unclear, but the simultaneous high-resolution measurements combined under these two missions are expected to provide an answer.

ESA is contributing eight scientific instruments to the mission, seven of which are Cluster-derived units.

These are the first ever European experiments to fly on a Chinese satellite. ESA will also be providing ground segment support, four hours each day, via its Villafranca satellite tracking station in Spain.

Scientific cooperation between China and ESA goes back quite a long way. A first Agreement signed back in 1980 facilitated the exchange of scientific information. Thirteen years later, the collaboration focused on a specific mission, Cluster, to study the Earth’s magnetosphere.

Then, in 1997, came a big step forward. The CNSA invited ESA to participate in the Double Star dual-satellite mission to study the Earth?s magnetic field, from a perspective different but complementary to Cluster’s. The Agreement to carry out this joint mission was signed on 9 July 2001 by ESA?s then Director General Antonio Rodot? and CNSA Administrator Luan Enjie.

For Professor David Southwood, ESA?s Science Programme Director: ?Today?s successful launch marks the culmination of these joint efforts and a further important step forward in this historic collaboration between China and Europe.?

Original Source: ESA News Release

Posted on by Fraser Cain

NASA Fights to Save Budget

Image credit: NASA
Administrator Sean O’Keefe today acknowledged the tough financial decisions that have to be made by Congress in passing the fiscal year 2005 budget, but asked the chairman of the U.S. House Committee on Appropriations to restore more than $1 billion of recommended cuts made Tuesday by the appropriations subcommittee.

“Over the course of the past year, Congress has called for the President to articulate a vision and strategy for space exploration. The President’s budget proposes the means to support the Vision for Space Exploration while the Subcommittee’s position does not provide the resources,” said the Administrator in a letter to Committee Chairman C. W. Bill Young, Republican congressman from Florida’s 10th District. “We are encouraged that the Subcommittee endorsed the Vision for Space Exploration in their markup, indicating they are hopeful that it may be possible to augment NASA funding as the appropriations process moves forward.”

Tuesday, members of the subcommittee recommended to the full Appropriations Committee a $15.1 billion budget for NASA, cutting about $1.1 billion from the President’s 2005 fiscal year submission. The NASA budget is part of a $93 billion spending bill that also provides funding for the Department of Veterans Affairs, the Department of Housing and Urban Development, the National Science Foundation and the Environmental Protection Agency.

“The Subcommittee-recommended funding level for NASA would adversely affect its ongoing science and technology programs, as well as the NASA workforce, and will delay plans for FY 2005 critical technology design efforts needed to better define the architecture in support of the Vision for Space Exploration,” the Administrator continued in his letter. “It is very important that these design efforts go forward in FY 2005 to enable NASA to address the long-lead, high-risk requirements that will form the basis for informed decisions by Congress on next steps in the Exploration plan.”

The Administrator thanked Chairman Young for the Appropriation Committee’s support of the Vision for Space Exploration. Administrator O’Keefe said he would continue to seek Committee and Congressional support for full funding of the President’s 2005 budget as the appropriations process continues.

The entire letter may be found on the Internet at:

http://www.nasa.gov/pdf/62799main_072204_young_letter.pdf

Original Source: NASA News Release

Posted on by Fraser Cain

What Venus and Sunspots Have in Common

Scientists using measurements from NASA’s Solar Radiation and Climate Experiment (SORCE) satellite have discovered that Venus and sunspots have something in common: they both block some of the sun’s energy going to Earth.

Using data from NASA’s SORCE satellite, scientists noticed that, when Venus came between the Earth and the sun on June 8, the other planet reduced the amount of sunlight reaching Earth by 0.1 percent. This Venus transit occurs when, from an earthly perspective, Venus crosses in front of the sun. When it happens, once every 122 years, there are two transits eight years apart. The next crossing happens in 2012 and will be visible to people on the U.S. West Coast.

“Because of its distance from Earth, Venus appeared to be about the size of a sunspot,” said Gary Rottman, SORCE Principal Investigator and a scientist at the Laboratory for Atmospheric and Space Physics (LASP), at the University of Colorado at Boulder. The SORCE team had seen similar reductions in the sun’s energy coming Earthward during the October 2003 sunspot activity.

In October 2003 the Earth-bound sunlight dimmed 0.3 percent for about four days, due to three very large sunspot groups moving across the face of the sun.

“This is an unprecedented large decrease in the amount of sunlight, and it is comparable to the decrease that scientists estimate occurred in the seventeenth century,” Rottman said. That decrease lasted almost 50 years, and was likely associated with the exceptionally cold temperatures throughout Europe at that time, a period from the 1400s to the 1700s known as the “little ice age.”

Solar conditions during the little ice age were quite different, as there were essentially no sunspots. Astronomers of the time, like Galileo, kept a good record of sunspot activity before and during the period, encountering only about 50 sunspots in 30 years.

Rottman said, “Something very different was happening during the seventeenth century, and it produced a much more permanent change in the sun’s energy output at that time.” Today, the large sunspots are surrounded by bright areas called “faculae.” Faculae more than compensate for the decrease in sunlight from sunspots, and provide a net increase in sunlight when averaged over a few weeks.

The large number of sunspots occurring in October/November 2003 indicated a very active sun, and indeed many very large solar flares occurred at that time. SORCE observed the massive record-setting solar flares in x-rays. The flares were accompanied by large sunspots, which produced a 0.3 percent decrease in the sun’s energy output. SORCE simultaneously collected the energy from all wavelengths, something that had never been done before.

“The SORCE satellite instruments provide measurements of unprecedented accuracy, so the sun’s energy output is known with great precision, and precise knowledge of variations in the sun’s energy input to Earth is a necessary prerequisite to understanding Earth’s changing climate,” said Robert F. Cahalan, SORCE Project Scientist and Head of the Climate and Radiation Branch at NASA’s Goddard Space Flight Center, Greenbelt, Md.

The SORCE measurements provide today’s atmospheric and climate scientists with essential information on the sun’s energy input to the Earth. These measurements also will be valuable to future scientists, who will be relating their view of the world back to conditions existing today. Likewise Galileo’s findings about the sun almost 400 years ago have increased in value as understanding of the sun and its importance for Earth has advanced.

For more SORCE information and images on the Internet, visit:

hthttp://www.gsfc.nasa.gov/topstory/2004/0730sunblockers.html
and
http://lasp.colorado.edu/sorce/

Original Source: NASA News Release