Nasa Technology News

Eight years after landing on Mars for what was planned as a three-month mission, NASA's enduring Mars Exploration Rover Opportunity is working on what essentially became a new mission five months ago.

Opportunity reached a multi-year driving destination, Endeavour Crater, in August 2011. At Endeavour's rim, it has gained access to geological deposits from an earlier period of Martian history than anything it examined during its first seven years. It also has begun an investigation of the planet's deep interior that takes advantage of staying in one place for the Martian winter.

Opportunity landed in Eagle Crater on Mars on Jan. 25, 2004, Universal Time and EST (Jan. 24, PST), three weeks after its rover twin, Spirit, landed halfway around the planet. In backyard-size Eagle Crater, Opportunity found evidence of an ancient wet environment. The mission met all its goals within the originally planned span of three months. During most of the next four years, it explored successively larger and deeper craters, adding evidence about wet and dry periods from the same era as the Eagle Crater deposits.

In mid-2008, researchers drove Opportunity out of Victoria Crater, half a mile (800 meters) in diameter, and set course for Endeavour Crater, 14 miles (22 kilometers) in diameter.

"Endeavour is a window further into Mars' past," said Mars Exploration Rover Program Manager John Callas, of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The trek took three years. In a push to finish it, Opportunity drove farther during its eighth year on Mars -- 4.8 miles (7.7 kilometers) -- than in any prior year, bringing its total driving distance to 21.4 miles (34.4 kilometers).

The "Cape York" segment of Endeavour's rim, where Opportunity has been working since August 2011, has already validated the choice of Endeavour as a long-term goal. "It's like starting a new mission, and we hit pay dirt right out of the gate," Callas said.

The first outcrop that Opportunity examined on Cape York differs from any the rover had seen previously. Its high zinc content suggests effects of water. Weeks later, at the edge of Cape York, a bright mineral vein identified as hydrated calcium sulfate provided what the mission's principal investigator, Steve Squyres of Cornell University, Ithaca, N.Y., calls "the clearest evidence for liquid water on Mars that we have found in our eight years on the planet."

Mars years last nearly twice as long as Earth years. Entering its ninth Earth year on Mars, Opportunity is also heading into its fifth Martian winter. Its solar panels have accumulated so much dust since Martian winds last cleaned them -- more than in previous winters -- the rover needs to stay on a sun-facing slope to have enough energy to keep active through the winter.

Source: http://www.jpl.nasa.gov/news/news.cfm?release=2012-022

The largest solar particle event since 2005 has been detected by the radiation- monitoring instrument aboard the Mars Science Laboratory spacecraft, on its way from Earth to Mars.

The Radiation Assessment Detector, inside the mission's Curiosity rover tucked inside the spacecraft, is measuring the radiation exposure that could affect a human astronaut on a potential Mars mission. It has measured an increase resulting from a Jan. 22 solar storm observed by other NASA spacecraft. No harmful effects to the Mars Science Laboratory have been detected from this solar event.

For more information about what effects the radiation detector has measured, visit: http://www.swri.org/9what/releases/2012/rad-solarstorm.htm .

Though generally thought to be quite dry, roughly half of the giant asteroid Vesta is expected to be so cold and to receive so little sunlight that water ice could have survived there for billions of years, according to the first published models of Vesta's average global temperatures and illumination by the sun.

"Near the north and south poles, the conditions appear to be favorable for water ice to exist beneath the surface," says Timothy Stubbs of NASA's Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland, Baltimore County. Stubbs and Yongli Wang of the Goddard Planetary Heliophysics Institute at the University of Maryland published the models in the January 2012 issue of the journal Icarus. The models are based on information from telescopes including NASA's Hubble Space Telescope.

Vesta, the second-most massive object in the asteroid belt between Mars and Jupiter, probably does not have any significant permanently shadowed craters where water ice could stay frozen on the surface all the time, not even in the roughly 300-mile-diameter (480-kilometer-diameter) crater near the south pole, the authors note. The asteroid isn't a good candidate for permanent shadowing because it is tilted on its axis at about 27 degrees, which is even greater than Earth's tilt of roughly 23 degrees. In contrast, the moon, which does have permanently shadowed craters, is tilted at only about 1.5 degrees. As a result of its large tilt, Vesta has seasons, and every part of the surface is expected to see the sun at some point during Vesta's year.

The presence or absence of water ice on Vesta tells scientists something about the tiny world's formation and evolution, its history of bombardment by comets and other objects, and its interaction with the space environment. Because similar processes are common to many other planetary bodies, including the moon, Mercury and other asteroids, learning more about these processes has fundamental implications for our understanding of the solar system as a whole. This kind of water ice is also potentially valuable as a resource for further exploration of the solar system.

Though temperatures on Vesta fluctuate during the year, the model predicts that the average annual temperature near Vesta's north and south poles is less than roughly minus 200 degrees Fahrenheit (145 kelvins). That is the critical average temperature below which water ice is thought to be able to survive in the top 10 feet or so (few meters) of the soil, which is called regolith.

Source: http://www.jpl.nasa.gov/news/news.cfm?release=2012-024

During GRAIL's science mission, the two spacecraft will transmit radio signals precisely defining the distance between them. As they fly over areas of greater and lesser gravity caused by visible features such as mountains and craters, and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly.

Scientists will translate this information into a high-resolution map of the moon's gravitational field. The data will allow scientists to understand what goes on below the lunar surface. This information will increase knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds we see today.

Each spacecraft carries a small camera called GRAIL MoonKAM (Moon Knowledge Acquired by Middle school students) with the sole purpose of education and public outreach. The MoonKAM program is led by Sally Ride, America's first woman in space, and her team at Sally Ride Science in collaboration with undergraduate students at the University of California in San Diego.

GRAIL MoonKAM will engage middle schools across the country in the GRAIL mission and lunar exploration. Thousands of fifth- to eighth-grade students will select target areas on the lunar surface and send requests to the GRAIL MoonKAM Mission Operations Center in San Diego. Photos of the target areas will be sent back by the GRAIL satellites for students to study.

A student contest that began in October 2011 also will choose new names for the spacecraft. The new names are scheduled to be announced in January 2012. Ride and Maria Zuber, the mission's principal investigator at the Massachusetts Institute of Technology in Cambridge, chaired the final round of judging.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the GRAIL mission for NASA's Science Mission Directorate, Washington. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft. JPL is a division of the Çalifornia Institute of Technology in Pasadena.

Scientists analyzing data from NASA's Cassini spacecraft now have the first-ever, up-close details of a Saturn storm that is eight times the surface area of Earth.

On Dec. 5, 2010, Cassini first detected the storm that has been raging ever since. It appears approximately 35 degrees north latitude of Saturn. Pictures from Cassini's imaging cameras show the storm wrapping around the entire planet covering approximately 2 billion square miles (4 billion square kilometers).

The storm is about 500 times larger than the biggest storm previously seen by Cassini during several months from 2009 to 2010. Scientists studied the sounds of the new storm's lightning strikes and analyzed images taken between December 2010 and February 2011. Data from Cassini's radio and plasma wave science instrument showed the lightning flash rate as much as 10 times more frequent than during other storms monitored since Cassini's arrival to Saturn in 2004. The data appear in a paper published this week in the journal Nature.

"Cassini shows us that Saturn is bipolar," said Andrew Ingersoll, an author of the study and a Cassini imaging team member at the California Institute of Technology in Pasadena, Calif. "Saturn is not like Earth and Jupiter, where storms are fairly frequent. Weather on Saturn appears to hum along placidly for years and then erupt violently. I'm excited we saw weather so spectacular on our watch."

At its most intense, the storm generated more than 10 lightning flashes per second. Even with millisecond resolution, the spacecraft's radio and plasma wave instrument had difficulty separating individual signals during the most intense period. Scientists created a sound file from data obtained on March 15 at a slightly lower intensity period.

Cassini has detected 10 lightning storms on Saturn since the spacecraft entered the planet's orbit and its southern hemisphere was experiencing summer, with full solar illumination not shadowed by the rings. Those storms rolled through an area in the southern hemisphere dubbed "Storm Alley." But the sun's illumination on the hemispheres flipped around August 2009, when the northern hemisphere began experiencing spring.

At today's final landing of the space shuttle, we had the rare opportunity to witness history. We turned the page on a remarkable era and began the next chapter in our nation’s extraordinary story of exploration.

The brave astronauts of STS-135 are emblematic of the shuttle program. Skilled professionals from diverse backgrounds who propelled America to continued leadership in space with the shuttle's many successes. It is my great honor today to welcome them home.

I salute them and all of the men and women who have flown shuttle missions since the very first launch on April 12, 1981.

The shuttle program brought our nation many firsts. Many proud moments, some of which I was privileged to experience myself as a Shuttle commander. I was proud to be part of the shuttle program and will carry those experiences with me for the rest of my life.

As we move forward, we stand on the shoulders of these astronauts and the thousands of people who supported them on the ground – as well as those who cheered their triumphs and mourned their tragedies.

This final shuttle flight marks the end of an era, but today, we recommit ourselves to continuing human space flight and taking the necessary – and difficult – steps to ensure America’s leadership in human spaceflight for years to come.

I want to send American astronauts where we’ve never been before by focusing our resources on exploration and innovation, while leveraging private sector support to take Americans to the International Space Station in low Earth orbit.

Source:

The existence of a world with a double sunset, as portrayed in the film Star Wars more than 30 years ago, is now scientific fact. NASA's Kepler mission has made the first unambiguous detection of a circumbinary planet -- a planet orbiting two stars -- 200 light-years from Earth.

Unlike Star Wars’ Tatooine, the planet is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy. Previous research has hinted at the existence of circumbinary planets, but clear confirmation proved elusive. Kepler detected such a planet, known as Kepler-16b, by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

"This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki said. "Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now."

A research team led by Laurance Doyle of the SETI Institute in Mountain View, Calif., used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets. Kepler is the first NASA mission capable of finding Earth-size planets in or near the "habitable zone," the region in a planetary system where liquid water can exist on the surface of the orbiting planet.

Scientists detected the new planet in the Kepler-16 system, a pair of orbiting stars that eclipse each other from our vantage point on Earth. When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is occulted, or completely blocked, by the larger star.

Astronomers further observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body. The additional dimming in brightness events, called the tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit.

The gravitational tug on the stars, measured by changes in their eclipse times, was a good indicator of the mass of the third body. Only a very slight gravitational pull was detected, one that only could be caused by a small mass. The findings are described in a new study published Friday, Sept. 16, in the journal Science.

"Most of what we know about the sizes of stars comes from such eclipsing binary systems, and most of what we know about the size of planets comes from transits," said Doyle, who also is the lead author and a Kepler participating scientist. "Kepler-16 combines the best of both worlds, with stellar eclipses and planetary transits in one system."

This discovery confirms that Kepler-16b is an inhospitable, cold world about the size of Saturn and thought to be made up of about half rock and half gas. The parent stars are smaller than our sun. One is 69 percent the mass of the sun and the other only 20 percent. Kepler-16b orbits around both stars every 229 days, similar to Venus’ 225-day orbit, but lies outside the system’s habitable zone, where liquid water could exist on the surface, because the stars are cooler than our sun.

Source:

Often, comets are portrayed as harbingers of gloom and doom in movies and on television, but most pose no threat to Earth. Comet Elenin, the latest comet to visit our inner solar system, is no exception. Elenin will pass about 22 million miles (35 million kilometers) from Earth during its closest approach on Oct. 16, 2011.

Also known by its astronomical name C/2010 X1, the comet was first detected on Dec. 10, 2010 by Leonid Elenin, an observer in Lyubertsy, Russia, who made the discovery "remotely" using an observatory in New Mexico. At that time, Elenin was about 401 million miles (647 million kilometers) from Earth. Since its discovery, Comet Elenin has – as all comets do – closed the distance to Earth's vicinity as it makes its way closer to perihelion, its closest point to the sun.

NASA scientists have taken time over the last several months to answer your questions. Compiled below are the some of the most popular questions, with answers from Don Yeomans of NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and David Morrison of the NASA Astrobiology Institute at the NASA Ames Research Center in Moffett Field, Calif.

NASA has selected three proposals, including one from NASA's Jet Propulsion Laboratory in Pasadena, Calif., as Technology Demonstration Missions to transform space communications, deep space navigation and in-space propulsion capabilities. The projects will develop and fly a space solar sail, deep space atomic clock, and space-based optical communications system.

These crosscutting flight demonstrations were selected because of their potential to provide tangible, near-term products and infuse high-impact capabilities into NASA's future space operations missions. By investing in high payoff, disruptive technology that industry does not have today, NASA matures the technology required for its future missions while proving the capabilities and lowering the cost of government and commercial space activities.

"These technology demonstration missions will improve our communications, navigation and in-space propulsion capabilities, enable future missions that could not otherwise be performed, and build the technological capability of America's space industry," said NASA Chief Technologist Bobby Braun at NASA Headquarters in Washington. "Optical communication will enable rapid return of the voluminous data associated with sending spacecraft and humans to new frontiers. High-performance atomic clocks enable a level of spacecraft navigation precision and autonomous operations in deep space never before achieved, and solar sails enable new space missions through highly efficient station-keeping or propellant-less main propulsion capabilities for spacecraft."

The proposals selected for demonstration missions are:
-- Laser Communications Relay Demonstration, David J. Israel, principal investigator at NASA's Goddard Space Flight Center in Greenbelt, Md.
-- Deep Space Atomic Clock, Todd Ely, principal investigator at the California Institute of Technology/NASA's Jet Propulsion Laboratory in Pasadena, Calif.
-- Beyond the Plum Brook Chamber; An In-Space Demonstration of a Mission-Capable Solar Sail, Nathan Barnes, principal investigator at L'Garde Inc., of Tustin, Calif.

Technology Demonstration Missions are a vital element in NASA's space technology maturation pipeline. They prove feasibility in the environment of space and help advance innovations from concept to flight and use in missions. The advances anticipated from communications, navigation and in-space propulsion technology will allow future NASA missions to pursue bolder and more sophisticated science, enable human missions beyond low Earth orbit, and enable entirely new approaches to U.S. space operations.

The Laser Communications Relay demonstration mission will fly and validate a reliable, capable, and cost-effective optical communications technology. Optical communications technology provides data rates up to 100 times higher than today's systems, which will be needed for future human and robotic space missions. The technology is directly applicable to the next generation of NASA's space communications network. After the demonstration, the developed space and ground assets will be qualified for use by near-Earth and deep space missions requiring high bandwidth and a small ground station reception area.

The Deep Space Atomic Clock demonstration mission will fly and validate a miniaturized mercury-ion atomic clock that is 10-times more accurate than today's systems. This project will demonstrate ultra-precision timing in space and its benefits for one-way radio navigation. The investigation will fly as a hosted payload on an Iridium spacecraft and make use of GPS signals to demonstrate precision orbit determination and confirm the clock's performance. Precision timing and navigation is critical to the performance of a wide range of deep space exploration missions.

The Solar Sail demonstration mission will deploy and operate a sail area 7 times larger than ever flown in space. It is potentially applicable to a wide range of future space missions, including an advanced space weather warning system to provide more timely and accurate notice of solar flare activity. This technology also could be applied to economical orbital debris removal and propellant-less deep space exploration missions. The National Oceanic and Atmospheric Administration is collaborating with NASA and L'Garde Inc. on the demonstration.

The clock and solar sail will be ready for flight in three years. The optical communications team anticipates it will take four years to mature the technology for flight. NASA's Office of the Chief Technologist plans to make a total investment in these three missions of approximately $175 million, contingent on future appropriations. Each of the selected teams also will receive funding from partners who plan on using the technologies as part of future space missions.

Projects include all elements of the flight test demonstration including test planning, flight hardware, launch, ground operations, and post-testing assessment and reporting. Each team has proposed between one and two years of spaceflight operations and data analysis. To reduce cost, the technology demonstrations will ride to space with other payloads aboard commercially provided launch vehicles. Launches are anticipated in 2015 and 2016.

A NASA-led research team has confirmed what Walt Disney told us all along: Earth really is a small world, after all.

Since Charles Darwin's time, scientists have speculated that the solid Earth might be expanding or contracting. That was the prevailing belief, until scientists developed the theory of plate tectonics, which explained the large-scale motions of Earth's lithosphere, or outermost shell. Even with the acceptance of plate tectonics half a century ago, some Earth and space scientists have continued to speculate on Earth's possible expansion or contraction on various scientific grounds.

Now a new NASA study, published recently in Geophysical Research Letters, has essentially laid those speculations to rest. Using a cadre of space measurement tools and a new data calculation technique, the team detected no statistically significant expansion of the solid Earth.

So why should we care if Mother Nature is growing? After all, Earth's shape is constantly changing. Tectonic forces such as earthquakes and volcanoes push mountains higher, while erosion and landslides wear them down. In addition, large-scale climate events like El Nino and La Nina redistribute vast water masses among Earth's ocean, atmosphere and land.

Scientists care because, to put movements of Earth's crust into proper context, they need a frame of reference to evaluate them against. Any significant change in Earth's radius will alter our understanding of our planet's physical processes and is fundamental to the branch of science called geodesy, which seeks to measure Earth's shape and gravity field, and how they change over time.

To make these measurements, the global science community established the International Terrestrial Reference Frame. This reference frame is used for ground navigation and for tracking spacecraft in Earth orbit. It is also used to monitor many aspects of global climate change, including sea level rise and its sources; imbalances in ice mass at Earth's poles; and the continuing rebound of Earth's surface following the retreat of the massive ice sheets that blanketed much of Earth during the last Ice Age.

NASA's solar-powered Juno spacecraft lifted off from Cape Canaveral Air Force Station in Florida at 9:25 a.m. PDT (12:25 p.m. EDT) Friday to begin a five-year journey to Jupiter.

Juno's detailed study of the largest planet in our solar system will help reveal Jupiter's origin and evolution. As the archetype of giant gas planets, Jupiter can help scientists understand the origin of our solar system and learn more about planetary systems around other stars.

"Today, with the launch of the Juno spacecraft, NASA began a journey to yet another new frontier," NASA Administrator Charles Bolden said. "The future of exploration includes cutting-edge science like this to help us better understand our solar system and an ever-increasing array of challenging destinations."

After Juno's launch aboard an Atlas V rocket, mission controllers now await telemetry from the spacecraft indicating it has achieved its proper orientation, and that its massive solar arrays, the biggest on any NASA deep-space probe, have deployed and are generating power.

"We are on our way, and early indications show we are on our planned trajectory," said Jan Chodas, Juno project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We will know more about Juno's status in a couple hours after its radios are energized and the signal is acquired by the Deep Space Network antennas at Canberra."

Juno will cover the distance from Earth to the moon (about 250,000 miles or 402,336 kilometers) in less than one day's time. It will take another five years and 1,740 million miles (2,800 million kilometers) to complete the journey to Jupiter. The spacecraft will orbit the planet's poles 33 times and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover to learn more about its origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core.

With four large moons and many smaller moons, Jupiter forms its own miniature solar system. Its composition resembles that of a star, and if it had been about 80 times more massive, the planet could have become a star instead.

"Jupiter is the Rosetta Stone of our solar system," said Scott Bolton, Juno's principal investigator from the Southwest Research Institute in San Antonio. "It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined, and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary -- to interpret what Jupiter has to say."

Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.

The NASA Deep Space Network -- or DSN -- is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions.

JPL manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

For more information about Juno, visit http://www.nasa.gov/juno and http://missionjuno.swri.edu .

Galaxies once thought of as voracious tigers are more like grazing cows, according to a new study using NASA's Spitzer Space Telescope.

Astronomers have discovered that galaxies in the distant, early universe continuously ingested their star-making fuel over long periods of time. This goes against previous theories that the galaxies devoured their fuel in quick bursts after run-ins with other galaxies.

"Our study shows the merging of massive galaxies was not the dominant method of galaxy growth in the distant universe," said Ranga-Ram Chary of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. "We're finding this type of galactic cannibalism was rare. Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought."

Chary is the principal investigator of the research, appearing in the Aug. 1 issue of the Astrophysical Journal. According to his findings, these grazing galaxies fed steadily over periods of hundreds of millions of years and created an unusual amount of plump stars, up to 100 times the mass of our sun.

"This is the first time that we have identified galaxies that supersized themselves by grazing," said Hyunjin Shim, also of the Spitzer Science Center and lead author of the paper. "They have many more massive stars than our Milky Way galaxy."

Galaxies like our Milky Way are giant collections of stars, gas and dust. They grow in size by feeding off gas and converting it to new stars. A long-standing question in astronomy is: Where did distant galaxies that formed billions of years ago acquire this stellar fuel? The most favored theory was that galaxies grew by merging with other galaxies, feeding off gas stirred up in the collisions.

Chary and his team addressed this question by using Spitzer to survey more than 70 remote galaxies that existed 1 to 2 billion years after the Big Bang (our universe is approximately 13.7 billion years old). To their surprise, these galaxies were blazing with what is called H alpha, which is radiation from hydrogen gas that has been hit with ultraviolet light from stars. High levels of H alpha indicate stars are forming vigorously. Seventy percent of the surveyed galaxies show strong signs of H alpha. By contrast, only 0.1 percent of galaxies in our local universe possess this signature.

Previous studies using ultraviolet-light telescopes found about six times less star formation than Spitzer, which sees infrared light. Scientists think this may be due to large amounts of obscuring dust, through which infrared light can sneak. Spitzer opened a new window onto the galaxies by taking very long-exposure infrared images of a patch of sky called the GOODS fields, for Great Observatories Origins Deep Survey.

Further analyses showed that these galaxies furiously formed stars up to 100 times faster than the current star-formation rate of our Milky Way. What's more, the star formation took place over a long period of time, hundreds of millions of years. This tells astronomers that the galaxies did not grow due to mergers, or collisions, which happen on shorter timescales. While such smash-ups are common in the universe -- for example, our Milky Way will merge with the Andromeda galaxy in about 5 billion years -- the new study shows that large mergers were not the main cause of galaxy growth. Instead, the results show that distant, giant galaxies bulked up by feeding off a steady supply of gas that probably streamed in from filaments of dark matter.

Chary said, "If you could visit a planet in one of these galaxies, the sky would be a crazy place, with tons of bright stars, and fairly frequent supernova explosions."

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA.

Since 1611, humans have recorded the comings and goings of black spots on the sun. The number of these sunspots waxes and wanes 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 Laboratory 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, with 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 Earth, sending fast solar wind in Earth's direction. Only as they finally appeared closer to the poles in 2009 did the speed of the solar 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 has 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."

More than 30 years after they left Earth, NASA's twin Voyager probes are now at the edge of the solar system. Not only that, they're still working. And with each passing day they are beaming back a message that, to scientists, is both unsettling and thrilling.

The message is, "Expect the unexpected."

"It's uncanny," says Ed Stone of the California Institute of Technology in Pasadena, Voyager Project Scientist since 1972. "Voyager 1 and 2 have a knack for making discoveries."
Today, April 28, 2011, NASA held a live briefing to reflect on what the Voyager mission has accomplished--and to preview what lies ahead as the probes prepare to enter the realm of interstellar space in our Milky Way galaxy.

The adventure began in the late 1970s when the probes took advantage of a rare alignment of outer planets for an unprecedented Grand Tour. Voyager 1 visited Jupiter and Saturn, while Voyager 2 flew past Jupiter, Saturn, Uranus and Neptune. (Voyager 2 is still the only probe to visit Uranus and Neptune.)

When pressed to name the top discoveries from those encounters, Stone pauses, not for lack of material, but rather an embarrassment of riches. "It's so hard to choose," he says.

Stone's partial list includes the discovery of volcanoes on Jupiter's moon Io; evidence for an ocean beneath the icy surface of Europa; hints of methane rain on Saturn's moon Titan; the crazily-tipped magnetic poles of Uranus and Neptune; icy geysers on Neptune's moon Triton; planetary winds that blow faster and faster with increasing distance from the sun.

"Each of these discoveries changed the way we thought of other worlds," says Stone.

In 1980, Voyager 1 used the gravity of Saturn to fling itself slingshot-style out of the plane of the solar system. In 1989, Voyager 2 got a similar assist from Neptune. Both probes set sail into the void.

Sailing into the void sounds like a quiet time, but the discoveries have continued.

Stone sets the stage by directing our attention to the kitchen sink. "Turn on the faucet," he instructs. "Where the water hits the sink, that's the sun, and the thin sheet of water flowing radially away from that point is the solar wind. Note how the sun 'blows a bubble' around itself."

There really is such a bubble, researchers call it the "heliosphere," and it is gargantuan. Made of solar plasma and magnetic fields, the heliosphere is about three times wider than the orbit of Pluto. Every planet, asteroid, spacecraft, and life form belonging to our solar system lies inside.

The Voyagers are trying to get out, but they're not there yet. To locate them, Stone peers back into the sink: "As the water [or solar wind] expands, it gets thinner and thinner, and it can't push as hard. Abruptly, a sluggish, turbulent ring forms. That outer ring is the heliosheath--and that is where the Voyagers are now."

The heliosheath is a very strange place, filled with a magnetic froth no spacecraft has ever encountered before, echoing with low-frequency radio bursts heard only in the outer reaches of the solar system, so far from home that the sun is a mere pinprick of light.

"In many ways, the heliosheath is not like our models predicted," says Stone.

In June 2010, Voyager 1 beamed back a startling number: zero. That's the outward velocity of the solar wind where the probe is now. No one thinks the solar wind has completely stopped; it may have just turned a corner. But which way? Voyager 1 is trying to figure that out through a series of "weather vane" maneuvers, in which the spacecraft turns itself in a different direction to track the local breeze. The old spacecraft still has some moves left, it seems.

No one knows exactly how many more miles the Voyagers must travel before they "pop free" into interstellar space. Most researchers believe, however, that the end is near. "The heliosheath is 3 to 4 billion miles in thickness," estimates Stone. "That means we'll be out within five years or so."

There is plenty of power for the rest of the journey. Both Voyagers are energized by the radioactive decay of a Plutonium 238 heat source. This should keep critical subsystems running through at least 2020.

After that, he says, "Voyager will become our silent ambassador to the stars."

Each probe is famously equipped with a Golden Record, literally, a gold-coated copper phonograph record. It contains 118 photographs of Earth; 90 minutes of the world's greatest music; an audio essay entitled Sounds of Earth (featuring everything from burbling mud pots to barking dogs to a roaring Saturn 5 liftoff); greetings in 55 human languages and one whale language; the brain waves of a young woman in love; and salutations from the secretary general of the United Nations. A team led by Carl Sagan assembled the record as a message to possible extraterrestrial civilizations that might encounter the spacecraft.

"A billion years from now, when everything on Earth we've ever made has crumbled into dust, when the continents have changed beyond recognition and our species is unimaginably altered or extinct, the Voyager record will speak for us," wrote Carl Sagan and Ann Druyan in an introduction to a CD version of the record.

Some people note that the chance of aliens finding the Golden Record is fantastically remote. The Voyager probes won't come within a few light years of another star for some 40,000 years. What are the odds of making contact under such circumstances?

On the other hand, what are the odds of a race of primates evolving to sentience, developing spaceflight, and sending the sound of barking dogs into the cosmos?
Expect the unexpected, indeed.

The Voyagers were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft. JPL is a division of the California Institute of Technology in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate.

For more information about the Voyager spacecraft, visit: http://voyager.jpl.nasa.gov and http://www.nasa.gov/voyager .

NASA's Jet Propulsion Laboratory in Pasadena, Calif., will host a Tweetup on Monday, June 6. More than 100 NASA Twitter followers, who registered in April, will attend the event.

With four NASA/JPL space missions launching in 2011 and an asteroid belt encounter nearly underway, this year will be one of the busiest ever in planetary exploration. Tweetup participants will interact with JPL scientists and engineers about these upcoming missions: Aquarius, to study ocean salinity; Grail, to study the moon's gravity field; Juno to Jupiter; and the Mars Science Laboratory/Curiosity rover. Tweetup participants also will learn about the Dawn mission and its planned encounter with the asteroid Vesta.

The Tweetup will take place from approximately 8 a.m. to 5:30 p.m. PDT. The event will be carried live on http://www.ustream.tv/nasajpl2 , and portions will also be broadcast on NASA Television from about 8:15 - 10:30 a.m. PDT and 1:30 - 3:30 p.m. PDT on June 6 at: http://www.nasa.gov/ntv.

The event will include a tour of JPL, hands-on demonstrations and a last chance to see the Curiosity rover before it ships to Florida for its launch in the fall. Tour stops will include the Spacecraft Assembly Facility, where Curiosity is undergoing assembly and testing, the mission control center of NASA's Deep Space Network, and JPL's new Earth Science Center.

Tweetup participants will mingle with fellow attendees and the staff behind @NASA, @NASAJPL, @MarsRovers, @AsteroidWatch and other NASA social media accounts.

NASA's first Tweetup was held at JPL on Jan. 21, 2009, and NASA Headquarters held its first on July 21, 2009. The most recent event was at NASA's Kennedy Space Center for the space shuttle Endeavour's final launch. Following JPL's June event, the next NASA Tweetup will be July 7-8 at Kennedy for the Space Shuttle Program's final launch. Registration for that Tweetup is open from noon EDT (9 a.m. PDT) Wednesday, June 1, through noon Thursday, June 2, at: http://www.nasa.gov/tweetup .

WEB COVERAGE
Follow the conversation before and during the June 6 event on Twitter by using the hashtag #NASATweetup and following the @NASAJPL, @JPLTweetup, and @NASATweetup accounts.

Find all the ways to connect and collaborate with NASA at: http://www.nasa.gov/connect .

The three massive solar panels that will provide power for NASA's Juno spacecraft during its mission to Jupiter have seen their last photons of light until they are deployed in space after launch. The last of the Jupiter-bound spacecraft's panels completed pre-flight testing at the Astrotech payload processing facility in Titusville, Fla., and was folded against the side of the spacecraft into its launch configuration Thursday, May 26. The solar-powered Juno spacecraft will orbit Jupiter's poles 30 times to find out more about the gas giant's origins, structure, atmosphere and magnetosphere.

"Completing the testing and stow of solar panels is always a big pre-launch milestone, and with Juno, you could say really big because our panels are really big," said Jan Chodas, Juno's project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The next time these three massive solar arrays are extended to their full length, Juno will be climbing away from the Earth at about seven miles per second."

This is the first time in history a spacecraft has used solar power so far out in space (Jupiter is five times farther from the sun than Earth). To operate on the sun's light that far out requires solar panels about the size of the cargo section of a typical tractor-trailer you'd see on the interstate highway. Even with all that surface area pointed sunward, all three panels, which are 2.7 meters wide (9 feet), by 8.9 meters long (29 feet), will only generate about enough juice to power five standard light bulbs -- about 450 watts of electricity. If the arrays were optimized to operate at Earth, they would produce 12 to 14 kilowatts of power.

In other recent events, the 106-foot-long (32-meter-long), 12.5-foot-wide (3.8-meter-wide) first stage of the United Launch Alliance Atlas V launch vehicle that will carry Juno into space arrived at the Skid Strip at Cape Canaveral Air Force Station on May 24, aboard the world's second largest cargo aircraft -- a Volga-Dnepr Antonov AN-124-100. The two-stage Atlas V, along with the five solid rocket boosters that ring the first stage, will be assembled and tested on site at Launch Complex-41 at Cape Canaveral this summer.

The launch period for Juno opens Aug. 5, 2011, and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 8:39 a.m. PDT (11:39 am EDT) and remains open through 9:39 a.m. PDT (12:39 p.m. EDT).

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

More information about Juno is online at http://www.nasa.gov/juno .

You can learn more about the Juno mission to Jupiter by logging on to the mission's new website. The new site was created by Juno Principal Investigator Scott Bolton in conjunction with Radical Media of New York. "It is one-stop shopping for anyone who wants to be entertained as much as informed about space science and the upcoming Juno mission," said Bolton. This Juno website can be found at: http://missionjuno.swri.edu .

Ancient astronomers looked up at the dark skies in wonder, as the stars marched by overhead like precision dancers. In the early 17th century, Galileo Galilei brought the world one step closer to the heavens with his telescope, discovering, among other celestial marvels, moons around Jupiter, and our own moon's pockmarked surface.

Nowadays, the stars are closer to us than ever, thanks to powerful telescopes in space and on the ground. Modern astronomers don't have to step outside, because they get precise data delivered straight to their own laptops. If Galileo could see us now, he'd probably be thrilled by the advances -- and also a little puzzled that astronomy no longer means gazing through telescopes at the twinkling, dark skies.

"You can access a priceless wealth of astronomy data from your couch," said Amy Mainzer, the deputy project scientist for NASA's Wide-field Infrared Survey Explorer mission at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We can do almost all of our research on our laptops."

Sometimes astronomers do take trips out to ground-based observatories. They sleep during the day, and, instead of peering up at the night sky, they command the telescopes from computer screens. Some telescopes can also be operated remotely from laptops. Mainzer and a colleague, Mike Cushing, a member of the WISE team at JPL, recently spent an evening with the stars in a conference room at NASA's Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena.

"I guess in some sense, there is a slight loss of romance doing remote observing," said Cushing. "But it is more than made up for by being able to sleep in your own bed!"

This particular night, Mainzer and Cushing, along with an undergraduate student, Emily DeBaun from Dartmouth College in Hanover, N.H., were on a hunt for brown dwarfs. These are cool, dim stars with somewhat stunted development. They begin life like stars, but never grow massive enough to ignite nuclear fusion and shine with sunlight, as our sun does so brilliantly. Instead, brown dwarfs glow because of the heat leftover from their formation. This heat makes them easy to see with infrared telescopes.

The first brown dwarf wasn't discovered until 1995, though these objects had been predicted to exist as far back as the 1960s. More discoveries rolled in during the early 2000s with the help of data from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey, an infrared all-sky mapping project sponsored by the Infrared Analysis and Processing Center and the University of Massachusetts, Amherst.

The WISE mission promises to find even more of these little stars, with its improved infrared all-sky maps. In fact, WISE will likely more than double the number of known brown dwarfs out to 25 light-years from our sun, and it may even find one that's closer to us than our closet known star, Proxima Centauri, which is about 4 light-years away. The WISE telescope wrapped up its all-sky survey and went into hibernation in Feb. 2011, but astronomers are just now beginning to sift through the data.

Mainzer and Cushing had plucked a few good brown dwarf candidates out of the WISE data. Their next step was to use the NASA Infrared Telescope Facility atop Mauna Kea in Hawaii to gather more information on the objects, and figure out if they are indeed brown dwarfs, and not something else, such as a distant galaxy masquerading as a nearby, cool star. That's what brought them to a quiet conference room late at night, when even the most owlish of the astronomers usually working in the building had gone home.

"You've got Guidedog," said Cushing, talking via speaker-phone to the NASA Infrared Telescope Facility telescope operator in Hawaii. Guidedog is the name of one of the computers that controls the camera on the telescope. The operator took control of the computer in order to focus the telescope.

Throughout the night, Mainzer and Cushing told the operator when they were ready to point the telescope at a different patch of sky, while controlling the specific settings from a software interface on their laptops. The laptop screen was projected onto a big screen in the conference room, where they could get a better view of the software.

One task involved placing their objects of interest into thin windows, or slits, which mask other nearby stars. Once the command was given to capture an image, an instrument on the Infrared Telescope Facility, called a spectrometer, broke apart the object's light into its basic components, much as a prism disperses sunlight into a rainbow. These data were then transformed into plots, called spectra, showing the various light intensities at each wavelength. The resulting peaks and dips revealed molecules making up the object, as well as its temperature.

"I think we bagged another T-dwarf," said Mainzer, referring to a classification system that organizes brown dwarfs according to their temperature. T-dwarfs are about 1,400 to 500 Kelvin (about 1,130 to 230 degrees Celsius). WISE will likely find even colder brown dwarfs, possibly even the elusive Y-dwarfs, which some theories say could be as cold as 200 Kelvin (minus 73 degrees Celsius). If such an object is revealed, it would be the coldest star-like body known.

The search for brown dwarfs continued on into night. Keeping the astronomers awake were bags of sweet-and-sour gummies and M&Ms, not to mention the thrill of discovering new worlds.

They stayed up until about 3 a.m. that night, which was midnight in Hawaii. The telescope was then handed off to another team of remote observers.

"We're still up late with the stars, even though we see them with electronic sensors instead of peering through the telescope with our own eyes," said Mainzer. "But compared to ancient astronomers, I think our sense of awe is the same, and we’re continuing the quest to understand our astonishing universe."

NASA has ended operational planning activities for the Mars rover Spirit and transitioned the Mars Exploration Rover Project to a single-rover operation focused on Spirit's still-active twin, Opportunity.

This marks the completion of one of the most successful missions of interplanetary exploration ever launched.

Spirit last communicated on March 22, 2010, as Martian winter approached and the rover's solar-energy supply declined. The rover operated for more than six years after landing in January 2004 for what was planned as a three-month mission. NASA checked frequently in recent months for possible reawakening of Spirit as solar energy available to the rover increased during Martian spring. A series of additional re-contact attempts ended today, designed for various possible combinations of recoverable conditions.

"Our job was to wear these rovers out exploring, to leave no unutilized capability on the surface of Mars, and for Spirit, we have done that," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Spirit drove 4.8 miles (7.73 kilometers), more than 12 times the goal set for the mission. The drives crossed a plain to reach a distant range of hills that appeared as mere bumps on the horizon from the landing site; climbed slopes up to 30 degrees as Spirit became the first robot to summit a hill on another planet; and covered more than half a mile (nearly a kilometer) after Spirit's right-front wheel became immobile in 2006. The rover returned more than 124,000 images. It ground the surfaces off 15 rock targets and scoured 92 targets with a brush to prepare the targets for inspection with spectrometers and a microscopic imager.

"What's really important is not only how long Spirit worked or how far Spirit drove, but also how much exploration and scientific discovery Spirit accomplished," Callas said.

One major finding came, ironically, from dragging the inoperable right-front wheel as the rover was driving backwards in 2007. That wheel plowed up bright white soil. Spirit's Alpha Particle X-ray Spectrometer and Miniature Thermal Emission Spectrometer revealed that the bright material was nearly pure silica.

"Spirit's unexpected discovery of concentrated silica deposits was one of the most important findings by either rover," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for Spirit and Opportunity. "It showed that there were once hot springs or steam vents at the Spirit site, which could have provided favorable conditions for microbial life."

The silica-rich soil neighbors a low plateau called Home Plate, which was Spirit's main destination after the historic climb up Husband Hill. "What Spirit showed us at Home Plate was that early Mars could be a violent place, with water and hot rock interacting to make what must have been spectacular volcanic explosions. It was a dramatically different world than the cold, dry Mars of today," said Squyres.

The trove of data from Spirit could still yield future science revelations. Years of analysis of some 2005 observations by the rover's Alpha Particle X-ray Spectrometer, Miniature Thermal Emission Spectrometer and Moessbauer Spectrometer produced a report last year that an outcrop on Husband Hill bears a high concentration of carbonate. This is evidence of a wet, non-acidic ancient environment that may have been favorable for microbial life.

"What's most remarkable to me about Spirit's mission is just how extensive her accomplishments became," said Squyres. "What we initially conceived as a fairly simple geologic experiment on Mars ultimately turned into humanity's first real overland expedition across another planet. Spirit explored just as we would have, seeing a distant hill, climbing it, and showing us the vista from the summit. And she did it in a way that allowed everyone on Earth to be part of the adventure."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rovers Opportunity and Spirit for the NASA Science Mission Directorate, Washington. For more about the rovers, see: http://www.nasa.gov/rovers and http://marsrovers.jpl.nasa.gov.

A few billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. This will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars.

To better understand collisions like these, astronomers have assembled an atlas of several galactic "train wrecks."

The new images combine observations from NASA's Spitzer Space Telescope, which observes infrared light, and NASA's Galaxy Evolution Explorer spacecraft, which observes ultraviolet light. By analyzing information from different parts of the light spectrum, scientists can learn much more about the collision process than from a single wavelength alone.

"We're working with the theorists to give our understanding a reality check," said the lead author of a paper on the results, Lauranne Lanz of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "Our understanding will really be tested in a few billion years, when the Milky Way experiences its own collision."

Read the full story from the Harvard-Smithsonian Center for Astrophysics at http://www.cfa.harvard.edu/news/2011/pr201117.html

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. More information is online at http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. JPL manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.

More information is online at http://www.nasa.gov/galex/ and http://www.galex.caltech.edu

You may have heard the news: Comet Elenin is coming to the inner-solar system this fall. Comet Elenin (also known by its astronomical name C/2010 X1), was first detected on Dec. 10, 2010 by Leonid Elenin, an observer in Lyubertsy, Russia, who made the discovery "remotely" using the ISON-NM observatory near Mayhill, New Mexico. At the time of the discovery, the comet was about 647 million kilometers (401 million miles) from Earth. Over the past four-and-a-half months, the comet has – as comets do – closed the distance to Earth's vicinity as it makes its way closer to perihelion (its closest point to the sun). As of May 4, Elenin's distance is about 274 million kilometers (170 million miles).

"That is what happens with these long-period comets that come in from way outside our planetary system," said Don Yeomans of NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "They make these long, majestic, speedy arcs through our solar system, and sometimes they put on a great show. But not Elenin. Right now that comet looks kind of wimpy."

How does a NASA scientist define cometary wimpiness?

"We're talking about how a comet looks as it safely flies past us," said Yeomans. "Some cometary visitors arriving from beyond the planetary region – like Hale-Bopp in 1997 -- have really lit up the night sky where you can see them easily with the naked eye as they safely transit the inner-solar system. But Elenin is trending toward the other end of the spectrum. You'll probably need a good pair of binoculars, clear skies, and a dark, secluded location to see it even on its brightest night."

Comet Elenin should be at its brightest shortly before the time of its closest approach to Earth on Oct. 16 of this year. At its closest point, it will be 35 million kilometers (22 million miles) from us. Can this icy interloper influence us from where it is, or where it will be in the future? What about this celestial object inspiring some shifting of the tides or even tectonic plates here on Earth? There have been some incorrect Internet speculations that external forces could cause comet Elenin to come closer.

"Comet Elenin will not encounter any dark bodies that could perturb its orbit, nor will it influence us in any way here on Earth," said Yeomans. "It will get no closer to Earth than 35 million kilometers [about 22 million miles]. "

"Comet Elenin will not only be far away, it is also on the small side for comets," said Yeomans. "And comets are not the most densely-packed objects out there. They usually have the density of something akin to loosely packed icy dirt.

"So you've got a modest-sized icy dirtball that is getting no closer than 35 million kilometers," said Yeomans. "It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean's tides than comet Elenin ever will."

Yeomans did have one final thought on comet Elenin.

"This comet may not put on a great show. Just as certainly, it will not cause any disruptions here on Earth. But there is a cause to marvel," said Yeomans. "This intrepid little traveler will offer astronomers a chance to study a relatively young comet that came here from well beyond our solar system's planetary region. After a short while, it will be headed back out again, and we will not see or hear from Elenin for thousands of years. That's pretty cool."

NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and predicts their paths to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.