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NASA Probe Sees Solar Wind Decline

The 33-year odyssey of NASA's Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind. Now hurtling toward interstellar space some 17.4 billion...

Super-Earth Atmosphere

A team of astronomers, including two NASA Sagan Fellows, has made the first characterizations of a super-Earth's atmosphere, by using a ground-based telescope...

Kepler Discovers

NASA's Kepler spacecraft has discovered the first confirmed planetary system with more than one planet crossing in front of, or transiting, the same star...

Pulverized Planet

Tight double-star systems might not be the best places for life to spring up, according to a new study using data from NASA's Spitzer Space Telescope....

Dark Asteroids

NASA is set to launch a sensitive new infrared telescope to seek out sneaky things in the night sky -- among them, dark asteroids that could pose a threat to Earth....

Archive for January 2010

The image covers a patch of sky about three times larger than the full moon. The patch was selected because it does not contain any unusually bright objects, which could damage instrument detectors if observed for too long. The picture was taken while the spacecraft was staring at a fixed patch of sky and is being used to calibrate the spacecraft's pointing system.

When the WISE survey begins, the spacecraft will scan the sky continuously as it circles the globe, while an internal scan mirror counteracts its motion. This allows WISE to take "freeze-frame" snapshots every 11 seconds, resulting in millions of images of the entire sky.
"Right now, we are busy matching the rate of the scan mirror to the rate of the spacecraft, so we will capture sharp pictures as our telescope sweeps across the sky," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

To sense the infrared glow of stars and galaxies, the WISE spacecraft cannot give off any detectable infrared light of its own. This is accomplished by chilling the telescope and detectors to ultra-cold temperatures. The coldest of WISE's detectors will operate at less than 8 Kelvin, or minus 445 Fahrenheit.
The first sky survey will be complete in six months, followed by a second scan of one-half of the sky lasting three months. The WISE mission ends when the frozen hydrogen that keeps the instrument cold evaporates away, an event expected to occur in October 2010.

Preliminary survey images are expected to be released six months later, in April 2011, with the final atlas and catalog coming after another 11 months in March 2012. Selected images will be released to the public beginning in February 2010.

Asteroid 2010 AL30, discovered by the LINEAR survey of MIT's Lincoln Laboratories on Jan. 10, will make a close approach to the Earth's surface to within 76,000 miles on Jan. 13 at 12:46 pm Greenwich time (7:46 am EST, 4:46 am PST). Because its orbital period is nearly identical to the Earth's one year period, some have suggested it may be a manmade rocket stage in orbit about the sun. However, this object's orbit reaches the orbit of Venus at its closest point to the sun and nearly out to the orbit of Mars at its furthest point, crossing the Earth's orbit at a very steep angle. This makes it very unlikely that 2010 AL30 is a rocket stage. Furthermore, trajectory extrapolations show that this object cannot be associated with any recent launch and it has not made any close approaches to the Earth since well before the Space Age began.

It seems more likely that this is a near-Earth asteroid about 10-15 meters in size, one of approximately 2 million such objects in near-Earth space. One would expect a near-Earth asteroid of this size to pass within the moon's distance about once every week on average. The asteroid does not pose a risk, in fact, stony asteroids under 25 meters in diameter would be expected to burn up in our atmosphere, causing little or no ground damage.

New results from NASA's Chandra X-ray Observatory and the Magellan telescopes suggest that a dense stellar remnant has been ripped apart by a black hole a thousand times as massive as the Sun. If confirmed, this discovery would be a cosmic double play: it would be strong evidence for an intermediate mass black hole, which has been a hotly debated topic, and would mark the first time such a black hole has been caught tearing a star apart.

This scenario is based on Chandra observations, which revealed an unusually luminous source of X-rays in a dense cluster of old stars, and optical observations that showed a peculiar mix of elements associated with the X-ray emission. Taken together, a case can be made that the X-ray emission is produced by debris from a disrupted white dwarf star that is heated as it falls towards a massive black hole. The optical emission comes from debris further out that is illuminated by these X-rays.

The intensity of the X-ray emission places the source in the "ultraluminous X-ray source" or ULX category, meaning that it is more luminous than any known stellar X-ray source, but less luminous than the bright X-ray sources (active galactic nuclei) associated with supermassive black holes in the nuclei of galaxies. The nature of ULXs is a mystery, but one suggestion is that some ULXs are black holes with masses between about a hundred and several thousand times that of the Sun, a range intermediate between stellar-mass black holes and supermassive black holes located in the nuclei of galaxies.

This ULX is in a globular cluster, a very old and crowded conglomeration of stars. Astronomers have suspected that globular clusters could contain intermediate-mass black holes, but conclusive evidence for this has been elusive.

NASA has selected three proposals as candidates for the agency's next space venture to another celestial body in our solar system. The final project selected in mid-2011 may provide a better understanding of Earth's formation or perhaps the origin of life on our planet.

The proposed missions would probe the atmosphere and crust of Venus; return a piece of a near-Earth asteroid for analysis; or drop a robotic lander into a basin at the moon's south pole to return lunar rocks back to Earth for study.

NASA will select one proposal for full development after detailed mission concept studies are completed and reviewed. The studies begin during 2010, and the selected mission must be ready for launch no later than Dec. 30, 2018. Mission cost, excluding the launch vehicle, is limited to $650 million.

"These are projects that inspire and excite young scientists, engineers and the public," said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "These three proposals provide the best science value among eight submitted to NASA this year."

Each proposal team initially will receive approximately $3.3 million in 2010 to conduct a 12-month mission concept study that focuses on implementation feasibility, cost, management and technical plans. Studies also will include plans for educational outreach and small business opportunities.

During the Maunder Minimum, a period of diminished solar activity between 1645 and 1715, sunspots were rare on the face of the sun, sometimes disappearing entirely for months to years. At the same time, Earth experienced a bitter cold period known as the "Little Ice Age."

Were the events connected? Scientists cannot say for sure, but it's quite likely. Slowdowns in solar activity -- evidenced by reductions in sunspot numbers -- are known to coincide with decreases in the amount of energy discharged by the sun. During the Little Ice Age, though, few would have thought to track total solar irradiance (TSI), the amount of solar energy striking Earth's upper atmosphere. In fact, the scientific instrument needed to make such measurements -- a spaceborne radiometer -- was still three centuries into the future.

Modern scientists have several tools for studying TSI. Since the 1970s, scientists have relied upon a collection of radiometers on American and European spacecraft to keep a close eye on solar fluctuations from above the atmosphere, which intercepts much of the sun's radiation. When NASA launches the Glory satellite this fall (no earlier than October 2009), researchers will have a more accurate instrument for measuring TSI than they've ever had before.

The Total Irradiance Monitor (TIM) on Glory is more sophisticated, but still related in concept to the very earliest ground-based solar radiometers, which were invented in 1838. Where those radiometers used sunlight to heat water and indicate the intensity of the sun's brightness at the Earth's surface, Glory's TIM instrument will use a black-coated metallic detector to measure how much heat is produced by solar radiation as it reaches the top of the Earth's atmosphere.

After nearly 5 years of concurrent operations with the Afternoon Constellation, known as the "A-Train," the PARASOL satellite is going on another orbit "track." The A-Train includes a number of NASA satellites that orbit the Earth one behind the other on the same track and until this month, PARASOL has been part of that train.

PARASOL is an Earth observation mission, managed by the French Space Agency (CNES). PARASOL stands for "Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar." According to CNES, it was maneuvered to leave its position inside the A-Train at 12:48 UTC, December 2, 2009.

The A-Train satellite formation currently consists of five satellites flying in close proximity: Aqua, CloudSat, CALIPSO, PARASOL and Aura. Each of these satellites cross the equator within a few minutes of each another at around 1:30 p.m. local time. By combining the different sets of nearly simultaneous observations, scientists are able to gain a better understanding its main mission, studying the important parameters related to climate change. As an additional benefit, the A-Train satellites provide unique information about tropical cyclones, the collective term for tropical depressions, tropical storms, hurricanes and typhoons.