A new report from the National Academies' National Research Council says that NASA will need to be more careful to prevent Earth microbes hitching a ride on spacecraft from contaminating Mars. Recent findings show that there could be liquid water underneath the ground on Mars, and some Earth bacteria can survive in such hostile environments. According to the report, NASA is planning to implement new techniques that would reduce the risk for spacecraft flying after 2016.

Cassini has obtained fascinating new images of the surface of Saturn's moon Enceladus. The spacecraft made its closest flyby so far on July 14, when it passed only 175 km (109 miles) within the moon's southern pole. This region is strangely free of impact craters, but it is littered with house-sized ice boulders. Enceladus has the most reflective surface in the solar system; it's as pure and white as freshly fallen snow. These gigantic blocks of ice were a complete surprise to scientists and they'll take some time to figure out what could have caused them.

The European Space Agency's SMART-1 spacecraft took this image of the Hadley Rille on the south-east edge of Mare Imbrium on the Moon. The bright bumps on the lower part of the image are the Appenine mountains, which formed a backdrop during the Apollo 15 mission in 1971. The Hadley Rille is a 120 km (76 mile) long gully - probably a collapsed lava tube - that formed about 3.3 billion years ago.

Astronomers have discovered that a relatively nearby galaxy is undergoing a tremendous amount of new star formation. This is very unusual, since galaxies normally only went through this phase billions of years ago, when the Universe was much younger. Seen in visible light, NGC 4625 only showed a diffuse halo, with a hint of spiral arms. But in the ultraviolet gaze of NASA's Galaxy Evolution Explorer, it clearly has vast spiral arms which extend four times the size of the galaxy's core.

Cassini has captured some strange-sounding radio emissions coming from Saturn's north and south poles. These emissions, called Saturn kilometric radiation, are generated by the planet's auroras. The changing frequencies probably come from tiny radio sources moving up and down the planet's magnetic field lines, but scientists are entirely sure what causes them. Cassini will fly close, or possibly even through, this region in 2008, so scientists will have a great opportunity to study them up close.

By creating a detailed map of Asteroid 433 Eros, a researcher from Cornell University has helped answer questions about its interior. Even though Eros is largely pockmarked from thousands of meteor strikes, it does have a few puzzling smooth parts. The smooth parts appear to have been caused by seismic waves that passed through the asteroid's interior and shook the ground smooth after it was hit by large impacts. This means that Eros' interior is cohesive enough to transmit these seismic waves.

Shevill Mathers took this picture of the Moon, Jupiter and Spica on the 13th July, 2005 from Tasmania, Australia. This image was taken with a Nikon D100 digital SLR with a Nikkor 80 to 200 f/2.8 zoom lens.

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Alonzo Villarreal took this picture of Sagittarius Star Cloud on June 2005 from Maricopa AZ. This image was taken with a Canon 350D with an exposure of around 5-10 seconds at ISO 1600 to minimize field rotation and a standard 18-55 Zoom.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

Narayan Mukkavilli took this picture of the Lagoon nebula on the 16th July, 2005 from Sydney, Australia. This image was taken with an ED80, Canon 300D digital SLR with an Astronomik 1.25 inch CLS filter.(CG5 mount, autoguided with Guide Dog, 5 inch newtonian guidescope.)

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Greetings, fellow SkyWatchers! This week will begin a series of studies of some of the oldest formations in our galaxy - globular clusters. The Moon will visit with Mars and lucky viewers in Australia will have a chance to see it occult the Pleiades! Not enough? Then hang on as we have not one - but two - meteor showers this week. So grab your binoculars, take out your telescopes and head for dark skies because...

Here's what's up!

NASA began the countdown for launch of the space shuttle Discovery on July 23. If all goes well, and there are no further delays, Discovery will blast off on Tuesday, July 26 at 1439 UTC (10:39 am EDT). They still have no resolution for the malfunctioning fuel gauge, but managers have said they'll be willing to let the shuttle fly, even if the problem resurfaces, because of redundant systems.

Saturn is about to go behind the Sun. For a few days, NASA won't be able to communicate with Cassini since it's currently in orbit the planet. As Saturn neared the edge on July 24, radio distortion from the Sun made communications with Cassini impossible. NASA expects to reacquire a signal from Cassini on July 27. This situation gives scientists an opportunity to probe the Sun's corona, since communications will have to pass through it. This photograph was taken by SOHO, which is parked in a gravitationally stable spot between the Earth and Sun.

Clyde Miller took this picture of Orion M42 from Brantford ON Canada.

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Clyde Miller took this picture of M5 on the 22nd June, 2005 from Brantford ON Canada.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

In this photograph, Cassini is looking through Saturn's rings to see the planet and one of its shepherd moons, Prometheus. The rings are casting a shadow onto the planet, and you can see the narrow, dense regions which are created by gravitational interaction with the shepherd moons. This picture was taken on June 3, 2005, when Cassini was 2.1 million kilometers (1.3 million miles) from Saturn.

With the evidence turned up by the Mars Exploration Rovers, the Red Planet was once warm enough to have liquid water flowing on its surface. But according to researchers at MIT that period happened a long time ago; more than 4 billion years ago, in fact. The team analyzed the amount of argon in various Martian meteorites. Since argon known to leak out of rocks at different rates depending on the temperature. they were able to provide this estimate for the age of the Martian deep freeze.

NASA's next mission to the Red Planet, the Mars Reconnaissance Orbiter (MRO), is in the final stages of preparation for launch. If all goes well, the spacecraft will lift off from Cape Canaveral atop an Atlas V on August 10, and begin the 7-month journey to reach Mars. MRO is carrying 6 instruments that will probe the planet's atmosphere, surface and subsurface and provide the most detailed examination so far.