Thursday, June 24, 2010

The Coolest Stars Come Out of the Dark

Astronomers have uncovered what appear to be 14 of the coldest stars known in our universe. These failed stars, called brown dwarfs, are so cold and faint that they'd be impossible to see with current visible-light telescopes. Spitzer's infrared vision was able to pick out their feeble glow, much as a firefighter uses infrared goggles to find hot spots buried underneath a dark forest floor.

The brown dwarfs join only a handful of similar objects previously discovered. The new objects are between the temperatures of about 450 Kelvin to 600 Kelvin (350 to 620 degrees Fahrenheit). As far as stars go, this is bitter cold -- as cold, in some cases, as planets around other stars.

These cool orbs have remained elusive for years, but will soon start coming out of the dark in droves. NASA's Wide-field Infrared Survey Explorer (WISE) mission, which is up scanning the entire sky now in infrared wavelengths, is expected to find hundreds of objects of a similarly chilly disposition, if not even colder. WISE is searching a volume of space 40 times larger than that sampled in the recent Spitzer study, which concentrated on a region in the constellation Boötes. The Spitzer mission is designed to look at targeted patches of sky in detail, while WISE is combing the whole sky.

Tuesday, June 22, 2010

Pacific Ocean sea surface

"The central equatorial Pacific Ocean could stay colder than normal into summer and beyond. That's because sea level is already about 10 centimeters (4 inches) below normal, creating a significant deficit of the heat stored in the upper ocean," said JPL oceanographer and climatologist Bill Patzert. "The next few months will reveal if the current cooling trend will eventually evolve into a long-lasting La Niña situation."

A La Niña is essentially the opposite of an El Niño. During a La Niña, trade winds in the western equatorial Pacific are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La Niñas change global weather patterns and are associated with less moisture in the air, resulting in less rain along the coasts of North and South America. They also tend to increase the formation of tropical storms in the Atlantic.

"For the American Southwest, La Niñas usually bring a dry winter, not good news for a region that has experienced normal rain and snowpack only once in the past five winters," said Patzert.

Thursday, June 17, 2010

Astronomers Discover Star-Studded Galaxy Tail

"The gas in this galaxy is being blown back into a turbulent wake," said Janice Hester of the California Institute of Technology in Pasadena, lead author of a recent study published in the Astrophysical Journal Letters. "The gas is like sand caught up by a stiff wind. However, the particular type of gas that is needed to make stars is heavier, like pebbles, and can't be blown out of the galaxy. The new Galaxy Evolution Explorer observations are teaching us that this heavier, star-forming gas can form in the wake, possibly in swirling eddies of gas."

Collisions between galaxies are a fairly common occurrence in the universe. Our Milky Way galaxy will crash into the Andromeda galaxy in a few billion years. Galaxies tangle together, kicking gas and dust all around. Often the battered galaxies are left with tails of material stripped off during the violence.

The astronomers were able to find this tail with the help of the Galaxy Evolution Explorer. Clusters of massive, young stars speckle the tail, and these stars glow with ultraviolet light that the space telescope can see. The young stars tell scientists that a crucial ingredient for star formation - dense clouds of gas called molecular hydrogen - formed in the wake of this galaxy's plunge. This is the first time astronomers have found solid evidence that clouds of molecular hydrogen can form under the violent conditions present in a turbulent wake.

Monday, June 14, 2010

JPL's Next Mars Rover Landing Radar Tested at Dryden

Testing for the JPL-managed Mars Science Laboratory or MSL project included suspending a full-scale engineering model of the MSL rover from a helicopter and flying pre-planned flight trajectories over Rogers Dry Lake at Edwards to simulate the rover's descent stage carrying the rover to the surface of Mars. JPL engineers needed to verify that the radar will provide accurate altitude and velocity measurements at Mars and that the suspended rover will not confuse the ability of the descent stage's radar to accurately calculate the rover's descent speed for a safe, on-target landing.

"Dryden offers a unique location to perform testing of this kind," said Carrie Rhoades, the Dryden flight operations engineer managing the MSL project at Dryden. "We have restricted airspace and a large dry lakebed that is useful in simulating several Mars-like features. Dryden is also conveniently close to JPL, so troubleshooting the system and fixing any issues has been relatively easy to accomplish," she said.

Saturday, June 12, 2010

ASTSAT Satellite Readies for Shipment to Alaska

The pre-shipment review was completed in May, demonstrating the flight hardware has successfully passed all environmental and performance tests and is authorized for shipment to the launch site for final integration on the Minotaur IV launch vehicle, built and operated by Orbital Sciences Corp. of Dulles, Va.

Engineers will pack the satellite into a shipping container for delivery in early July to the launch complex in Kodiak, Alaska. FASTSAT is scheduled to launch no earlier than Sept. 1, 2010.

Mission operations for FASTSAT and all six experiments will be managed from the newly configured small satellite control room at the Huntsville Operations and Science Control Center at the Marshall Space Flight Center.

"An outstanding team of engineers and scientists worked diligently to get us to this milestone," said FASTSAT Project Manager Mark Boudreaux at NASA's Marshall Space Flight Center in Huntsville. "We are ready to perform the remaining activities, ship the spacecraft to Alaska and integrate FASTSAT on the launch vehicle."

FASTSAT will be flying on the STP-S26 mission -- a joint activity between NASA and the U.S. Department of Defense Space Test Program, or DoD STP. FASTSAT and all of its six experiments flying on the STP–S26 multi-spacecraft/payload mission have been approved by the Department of Defense Space and Experiments Review Board.

"The outstanding work and accomplishments from the FASTSAT Team illustrate joint activities at their finest," said U.S. Air Force Col Stephen D. Hargis, DoD STP director at Kirtland Air Force Base, N.M. "This is a clear example of what is possible when NASA and the Air Force put their minds together for a common goal…mission success and maximizing access to space."

One of the six experiments on the FASTSAT bus, NanoSail-D, is designed to demonstrate deployment of a compact solar sail boom system that could lead to further development of this alternate propulsion technology and FASTSAT's ability to eject a nanosatellite from a microsatellite -- while avoiding re-contact with the FASTSAT satellite bus. NanoSail-D, managed by the Marshall Center, will be the first NASA solar sail deployed in low-Earth orbit. It was designed and built by NASA engineers at Marshall in collaboration with the Nanosatellite Missions Office at NASA's Ames Research Center in Moffett Field, Calif. This experiment is a combined effort between the U.S. Army Space and Missile Defense Command and the Von Braun Center for Science & Innovation, both located in Huntsville, and NASA.

Friday, June 04, 2010

Hubble Images Suggest Rogue Asteroid Smacked Jupiter

Without warning, a mystery object struck Jupiter on July 19, 2009, leaving a dark bruise the size of the Pacific Ocean. The spot first caught the eye of an amateur astronomer in Australia, and soon, observatories around the world, including NASA’s Hubble Space Telescope, were zeroing in on the unexpected blemish.

Astronomers had witnessed this kind of cosmic event before. Similar scars had been left behind during the course of a week in July 1994, when more than 20 pieces of Comet P/Shoemaker-Levy 9 (SL9) plunged into Jupiter’s atmosphere. The 2009 impact occurred during the same week, 15 years later.

Astronomers who compared Hubble images of both collisions say the culprit may have been an asteroid about 1,600 feet (500 meters) wide. The images, therefore, may show for the first time the immediate aftermath of an asteroid, rather than a comet, striking another planet.

The Jupiter bombardments reveal that the solar system is a rambunctious place, where unpredictable events may occur more frequently than first thought. Jupiter impacts were expected to occur every few hundred to few thousand years. Although there are surveys to catalogue asteroids, many small bodies may still go unnoticed and show up anytime to wreak havoc.

“This solitary event caught us by surprise, and we can only see the aftermath of the impact, but fortunately we do have the 1994 Hubble observations that captured the full range of impact phenomena, including the nature of the objects from pre-impact observations” says astronomer Heidi Hammel of the Space Science Institute in Boulder, Colo., leader of the Jupiter impact study.

In 2009 Hammel’s team snapped images of the debris field with Hubble’s recently installed Wide Field Camera 3 and newly repaired Advanced Camera for Surveys.

The analysis revealed key differences between the two collisions (in 1994 and 2009), providing clues to the 2009 event. Astronomers saw a distinct halo around the 1994 impact sites in Hubble ultraviolet (UV) images, evidence of fine dust arising from a comet-fragment strike. The UV images also showed a strong contrast between impact-generated debris and Jupiter’s clouds.