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Mountains of creation
A new image from NASA's Spitzer Space Telescope reveals billowing mountains of dust ablaze with the fires of stellar youth. The majestic infrared view from Spitzer resembles the iconic "Pillars of Creation" picture taken of the Eagle Nebula in visible light by NASA's Hubble Space Telescope.

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Space history: STS-51A
This week marks the anniversary of arguably the most daring and complex space shuttle mission. The astronauts successfully launched two satellites and then recovered two others during extraordinary spacewalks by astronauts using jet-propelled backpacks and pure muscle power.

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Space station EVA
Commander Bill McArthur and flight engineer Valery Tokarev conduct a 5 1/2-hour spacewalk outside the International Space Station, installing a TV camera, doing repair chores and jettisoning a failed science probe.

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The Earth from space
Return to flight space shuttle commander Eileen Collins narrates an interesting slide show featuring some favorite photographs of Earth taken during her previous shuttle missions.

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Griffin testifies
NASA Administrator Mike Griffin goes before the U.S. House of Representative's Science Committee to provide an update on the moon-Mars exploration program, the future of the space shuttle and space station, possible servicing of Hubble, cost overruns on the James Webb Space Telescope and the agency's aeronautics research.

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Dale hearing
The Senate Commerce Committee holds a confirmation hearing on President Bush's nomination of Shana Dale to be the new NASA deputy administrator, replacing former astronaut Fred Gregory.

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Astronaut Q&A
As NASA celebrates five years of continuous human presence aboard the International Space Station, former resident astronauts from Expedition crews who lived aboard the outpost held this recent question and answer session at the Johnson Space Center.

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Shuttle engine test
For the first time since Hurricane Katrina, NASA's Stennis Space Center in Mississippi conducts a test-firing of a space shuttle main engine. The engine was run as part of a certification series on the Advanced Health Management System, which monitors engine performance.

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Edwards air show
Edwards Air Force Base hosted an open house and air show this past weekend. NASA's Dryden Flight Research Center demonstrated some of its specialized aircraft -- a highly modified NF-15B, a high-altitude ER-2, and F/A-18 and T-34. On the ground, a variety of specialized air and space vehicles were on display in the NASA exhibit, ranging from the Mars rovers to the 747 space shuttle carrier aircraft.

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ISS science 'suitcases'
Scientists eagerly examine suitcase-like packages, called the Materials International Space Station Experiments, or MISSEs, after return to Earth. The MISSE packages were flown outside the orbiting station to expose different materials to the space environments for study.

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Tracking hurricanes
This 2005 Atlantic hurricane season has a been a record-breaker. Satellite imagery since June 1 has been compiled into this movie to track the 21 named storms as they formed and traveled, many making landfall.

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Space probe rehearses landing dance with asteroid

Posted: November 12, 2005

With over a month of detailed remote study behind it, Japan's Hayabusa asteroid probe is ready to reach out and touch a small space rock hidden in the black depths of the solar system after a critical weekend test run confirmed all was ready for the high stakes operation that will gather the first ever asteroid samples destined for return to Earth.

Hayabusa returned this image of the asteroid as the spacecraft toward the surface during the weekend rehearsal. The probe's shadow can be seen in the upper right. Credit: JAXA
However, the future of the mission is contingent on enough chemical propellant remaining in the probe's fuel reservoirs to carry out the remaining maneuvers before departing Itokawa, which has been described as "not optimistic" by one senior project official.

The craft is consuming more fuel than expected due to the loss of two of three reaction wheels in the past few months. The reaction wheels normally control the orientation of Hayabusa in three axes. Control teams were forced to devise a plan to reduce fuel use after the failures.

On its two-month anniversary in the vicinity of asteroid Itokawa, the Hayabusa science platform swooped within 100 meters, or around 330 feet, of the potato-shaped object that measures 2,000 feet by around 900 feet. Its orbit stretches from inside Earth's out to a distance of 157 million miles from the Sun, making it a member of the Apollo class of near-Earth asteroids that pose potential impact threats to our planet.

The plunge began early Saturday, Japan time, as Hayabusa methodically descended primarily under the control of its chemical thrusters fueled by nitrogen tetroxide and hydrazine-derived propellants.

The probe eventually maneuvered to its hovering position under 330 feet from Itokawa, where it released a tiny rover with an Earth weight of just over one pound. An update of the project's web site confirmed that officials received communications from the craft after its release, but the Japanese Kyodo news agency later reported the explorer was likely lost.

The MINERVA deployable asteroid lander is extremely tiny. Credit: JAXA
The deployment of MINERVA (Micro/Nano Experimental Robot Vehicle for Asteroid) occurred at approximately 0624 GMT (1:24 a.m. EDT), as computed by Hayabusa's on-board time. The miniscule 1.3-pound robot could take advantage of the low gravity of Itokawa to hop around its surface. Aboard the rover was a pair of stereo cameras for close observations with a resolution as low as just one millimeter, and another that was designed to peer into more distant regions.

At such close ranges, MINERVA could resolve minerals in rocks and pebbles, along with individual grains in loose regolith believed to be covering parts of the surface. A group of six thermometers were also fitted to the top and bottom of the rover to measure temperatures.

In the early parts of the mission's pre-launch development, NASA had planned to build a slightly more advanced 2.2-pound rover for inclusion on Hayabusa. That vehicle would have carried a camera along with infrared and X-ray spectrometers, but it was canceled five years ago this month after rising costs above the original $21 million estimate.

Hayabusa began ascending again after a short stay stationkeeping at the low altitude, and was expected to return to a position four miles away.

Saturday's descent also served as a dry run for two attempts later this month that will finish the trip to Itokawa's surface, where a 16-inch funnel will come in contact with the object and a metal pellet will be fired at up to several hundred miles per hour into the rocky crust.

The high-speed impact will blow rubble and dust through the funnel to be captured in a chamber, which will carry the cargo on the 18-month ride back to Earth and through the fiery re-entry back into the atmosphere. The total amount gathered is anticipated to be around one gram - or about two one-thousandths of a pound.

An artist's concept shows Hayabusa during its planned touchdown to collect samples of the asteroid. Credit: JAXA
The first approach is currently planned for Saturday, November 19, followed by a second descent on November 25. Hayabusa is facing a December deadline to fire up its ion engines and set a course for Earth, where it is due to parachute into the Australian outback at Woomera in June 2007.

The sampling rehearsal was aborted in its first try on November 4 after an anomaly was detected in the navigation computer at an altitude of about 2,300 feet. Once the craft returned to its start position, engineers found that the image processor aboard Hayabusa was at fault.

"The asteroid is seen usually (as) a single object, but depending on the aspect angle with the Sun's direction, the object is seen comprised of multi- or many objects, since boulders and terrain are partially illuminated," said Jun'ichiro Kawaguchi. "If many objects are identified aboard, (the) processor cannot determine aboard what the direction should be."

The problem was subsequently fixed, and Hayabusa confirmed the patch on Wednesday when the spacecraft came within 230 feet of Itokawa to test navigation and guidance systems. Images from both Wednesday and Saturday showed the shadow of the 1,000-pound probe against the asteroid.

Named after the Japanese word for "falcon," Hayabusa arrived 12 miles from Itokawa on September 12, after a journey from Earth that stretched over two years in length. The probe, formerly known as MUSES-C, was launched in May 2003 from Kagoshima, Japan. Its four cutting edge microwave discharge ion engines - fed by xenon gas - accomplished over 25,000 hours of operating time during the craft's trip through the solar system, before handing propulsion control over to Hayabusa's chemically-fueled thrusters.

The arrival at Itokawa had been delayed several months after a large solar flare in 2003 degraded electrical production aboard Hayabusa, which curtailed the operation of the ion engines for a period of time.

The rendezvous sequence was delicately controlled largely by an autonomous navigation system that reduces human intervention from ground teams on Earth 180 million miles away. This technology, along with the ion engine and others, can be incorporated into future robotic space missions.

After almost three weeks in what officials call the "gate position," Hayabusa maneuvered closer to Itokawa to the "home position" just over four miles from the asteroid's surface.

Shortly after this milestone, Hayabusa experienced the loss of its second reaction wheel in early October. The failure came after the probe lost its X-axis wheel in July, and combined the malfunctions caused the navigation system to burn more precious chemical propellant than expected.

An artist's concept shows the Hayabusa mission. Credit: JAXA
At the home position, the probe continued to carry out a comprehensive global study of the asteroid with its array of four instruments. Aboard Hayabusa are a visible camera that has captured over 1,500 images, a near-infrared spectrometer that has gathered over 75,000 measurements, a laser altimeter responsible for 1.4 million data sets, and an X-ray spectrometer that has over 700 hours of operating time.

Scientists observing Itokawa have been surprised by the wide variety of surface features found by the visiting probe. Contrary to earlier hypotheses that small near-Earth asteroids would have relatively uniform characteristics, images show both massive boulders and protrusions cover parts of the space rock, while smooth areas mark other regions.

Hayabusa also worked to locate potential sampling sites, and used its spectrometers to analyze the areas to remotely determine composition and other data.

Scientists narrowed the list of attractive targets to just two - a region of smooth and loose rock known as the MUSES Sea, and a broad, flat, and rocky area dubbed Woomera. After higher resolutions pictures of the latter site were beamed back to Earth, officials opted to attempt both sample runs at the MUSES Sea locale because of concern with potentially hazardous rocks and boulders at Woomera, named after the central Australian test site that will receive Hayabusa's return capsule.

The asteroid Itokawa is been observed up-close by the Hayabusa spacecraft for the past couple of months. Credit: JAXA
Ground teams have also combined images of the asteroid with navigation data to create a precise numerical model for the shape and gravity field of the asteroid. This allows scientists to better understand the unique environment the ultra-low gravity field of such a small object, and how it affects its evolution.

Data has also been used to determine mass and density estimates for Itokawa. "This may indicate there is substantial porosity for this body, and forces conventional views of these small objects to be changed drastically," the Japan Aerospace Exploration Agency, JAXA, said in a statement.

"The scientific discoveries reported here will redefine scientific notions and views of asteroids from the pre-Hayabusa era, and are a remarkable accomplishment that Japan has contributed to planetary exploration."

Asteroids offer scientists a glimpse back in time to the early solar system, when planets and other objects had just formed. Current information is confined only to remote studies and ground analysis of meteorites, and Hayabusa's returned samples will fill in the gap with a pristine source directly from space.