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MESSENGER reveals more of Mercury’s secrets

...the MESSENGER spacecraft successfully completed its second flyby of Mercury, unveiling another 30 percent of the planet’s surface...

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Evolving galaxies shed gas and fireballs

...astronomers studying the Coma Cluster of galaxies have discovered that galactic collisions are powerful enough to strip a galaxy of its gas and fling star-forming fireballs out into space...

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Small asteroid burns up in Earth’s atmosphere

...according to predictions, a three metre wide asteroid exploded in the Earth’s atmosphere at 0246 UT above northern Sudan on Tuesday...

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Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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Phoenix digs into darkness

Posted: October 09, 2008

As the Sun falls further and further below the horizon in northern hemisphere Mars, Phoenix continues to dig soil and deliver samples to its onboard laboratory for analysis.

The Mars Lander has been occupied with investigating the area around the 40 centimetre wide rock - nicknamed Headless - that it shifted into a trench around two weeks ago. Since then, it has been scraping soil from underneath the rock, delivering a few teaspoonfuls to the Microscopy, Electrochemistry and Conductivity Analyser.

This false colour image reveals colour variations in the trench informally named 'La Mancha,' and shows the ice layer beneath the soil surface as a dark grey sheet. The trench is about five centimetres deep. The colour outline of the shadow at the bottom of the image is a result of Sun movement with the combined use of infrared, green and blue filters. Image: NASA/JPL-Caltech/University of Arizona/Texas A&M University.

The soil sample has been nicknamed ‘Galloping Hessian’ and caught the attention of Phoenix mission scientists because it may contain a high concentration of salts. In arctic and arid environments on Earth, salt is left under and around rocks after water evaporates.

"That's why we wanted to look under Headless, to see if there's a higher concentration of salts there," says Phoenix mission scientist Diana Blaney of NASA's Jet Propulsion Laboratory.

The hard, icy layer underneath the Martian surface also continues to occupy Phoenix. The lander has dug a trench called La Mancha, underneath the original location of the ‘Headless’ rock, to investigate how deep the ice layer is set in this location. There are also plans to dig laterally across some of the existing trenches to reveal a horizontal profile of the ice layer, building up a three-dimensional picture of the distribution of ice in this local region of Mars.

"We'd like to see how the ice table varies around the workspace with the different topography and varying surface characteristics such as different rocks and soils," says Phoenix co-investigator Mike Mellon of the University of Colorado. "We hope to learn more about how the ice depth is controlled by physical processes, and by looking at how the ice depth varies, we can pin down how it got there."

It's frosty mornings for Phoenix from now on as the Sun begins to set on the mission. This image was taken at 9am on 18 September and shows bright, frosty material forming in and around the trench. Image NASA/JPL-Caltech/University of Arizona/ Texas A&M Univeristy.

The Phoenix lander is now in its fifth month of an originally planned three month mission, but the Sun is rapidly setting. The lander's weather instruments have detected water-ice haze clouds in the northern Martian sky, and temperatures are getting colder as the daylight hours wane. As solar power declines, Phoenix will become primarily a weather station before all activity ceases by the end of the year.

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