Today is the day that Cassini is scheduled to make its arrival at Saturn, flying close to the planet and threading between two of its ring systems. Controllers have released this natural colour image of Titan, Saturn's largest moon. The moon is surrounded by a thick atmosphere rich in organic molecules, which give it this featureless orange glow. Cassini will get a much better view soon, though, as it will make its first close flyby in just a few days. It will release the Huygens probe in early 2005 which will actually land on its surface and give scientists a better idea of what's beneath those thick clouds.

Here's a simple question: how long is a day on Saturn? The answer, it turns out is very complex. Cassini recently measured its day at just over 10 hours and 45 minutes, but this is a full 6 minutes longer than the Voyager spacecraft measured. If this is correct, Saturn has slowed down 1% in only 23 years. Length of day is usually measured by a radio telescope, watching as the magnetic field sweeps around. With Saturn, however, it looks like the planet isn't locked to its magnetic field, which can slip around to different latitudes.

The Spitzer Space Telescope has taken a picture of a galaxy called NGC 7331; astronomers believe it's a virtual twin of our own Milky Way galaxy. Since we're inside our galaxy, many of its interesting features are shrouded by dust, so looking at NGC 7331 is like looking into a mirror 50 million light-years away. Spitzer's infrared spectrograph has revealed that our twin seems to have an unusually high concentration of massive stars at its centre, or a moderately active supermassive black hole, similar to the one at the heart of our own Milky Way.

A Zenit-3SL rocket lifted off from the Sea Launch platform today, carrying a Telstar 18 satellite into orbit. The rocket launched at 0359 UTC (11:59 pm EDT June 28), but a glitch put the satellite into a transfer orbit that was lower than expected. Engineers think that they should still be able the satellite into its final orbit using station-keeping thrusters, which will shorten its lifespan. Telstar 18 will provide broadcast satellite services to East Asia and the Pacific Ocean.

Engineers have nearly gotten to the bottom of the problem that forced spacewalkers to abort their trip outside the International Space Station last week. The primary oxygen bottle on Mike Fincke's Russian-built Orlan spacesuit lost pressure much more quickly than expected, so he and cosmonaut Gennady Padalka were ordered back in the station after only 14 minutes. Russian specialists are focusing on an injector switch that increases the flow of oxygen into the spacesuit. The crew should be able to repair the problem themselves, and use the suits when the spacewalk is rescheduled.

Astronomers have found a white dwarf star which has shut down its fusion reactor very recently - perhaps only 100 years ago. By probing this star with the Chandra X-Ray Observatory and the Far Ultraviolet Spectroscopic Explorer (FUSE), astronomers see that its heart is completely stripped of hydrogen and helium; the surface is largely carbon and oxygen, heated to 200,000 degrees. Nothing like this has ever been seen. Our own Sun will eventually become a star like this, after it has expended all of its hydrogen fuel.

NASA's Cassini spacecraft has turned its gaze on smog-covered Titan again, delivering its best picture yet of Saturn's largest moon. This image was taken on June 14, 2004 when the spacecraft was 10.4 million km (6.5 million miles) away; it's three times as much resolution as the previous image of Titan released a few weeks ago. Cassini took the picture using a special filter designed to see through Titan's atmospheric haze of methane to the surface below.

There's a classic scene in the movie Apollo 13 when scientists and engineers brainstorm solutions to "scrub" the spacecraft's air to remove toxic levels of carbon dioxide. All they've got to work with is what the imperiled astronauts have on board their capsule. They devise a clever solution using what the astronauts have available, and save their lives.

It's a fitting analogy, I think, to the challenge faced by the commissioners for the President's Commission on Implementation of U.S. Space Exploration Policy, a.k.a. the Aldridge report. How do you fundamentally change NASA to make it both safer and more willing to take risks? To re-energize the dream of human spaceflight? To stop battling free enterprise and embrace it? To get humans back to the Moon, and then on to Mars?

"You've got these resources at your disposal, now fix NASA."

NASA Administrator Sean O'Keefe announced a series of changes to the agency to better prepare it to fulfill President Bush's new vision for human space exploration; to "make it leaner and more focused on its goals." NASA will merge seven existing enterprises into four mission directorates, to create clearer lines of communication and authority: Exploration Systems, Space Operations, Aeronautics Research, and the Science Directorate. Further changes are on the way.

Here's the photo we've all been waiting for. This 1024x768 wallpaper image of Saturn's moon Phoebe was created by the Space Science Institute, who stitched together 5 separate images of the moon taken by Cassini. Phoebe's surface is pockmarked with large and small craters, indicating that the moon is extremely old. Scientists think that it might be part of an ancient family of icy objects which were pushed to the outer Solar System to form the Kuiper Belt. Phoebe was caught by Saturn's enormous gravity before it could escape.

The Supernova Integral Field Spectrograph (SNIFS), a new instrument designed to examine exploding stars, has observed its first target: supernova SN 2004cr. Mounted on board the University of Hawaii's 2.2 metre telescope on Mauna Kea, the instrument is designed to simultaneously observe a supernova, its home galaxy, and the surrounding sky. It should make very precise measurements of Type 1A supernovae, which are considered by astronomers to be "standard candles" - every explosion is the same brightness, so you can use them to measure the distance to galaxies.

Scientists working with NASA's Cassini spacecraft have stitched together photos taken by the spacecraft to build a complete picture of Phoebe, a moon of Saturn that the spacecraft passed on June 11. The tiny moon is likely an ancient collection of ice, rock and carbon-containing compounds similar to Pluto and Neptune's moon Triton. Planetesimals like this could be very common in the outer reaches of the Solar System, as they were ejected during the early formation of the planets. Phoebe was probably captured early on by Saturn, perhaps 4 billion years ago.

A team of physicists from the University of California have built a cluster of nearly 300 computer processors capable of simulating some of the mysteries of the Universe. "The Space Simulator" has a theoretical performance of 1.5 teraflops, which places it at #344 on the list of the 500 fastest computers in the world. It was developed on a budget, though, at a cost of only $1,000 per processor; $500,000 for the whole cluster. It's been used to simulate the structure and evolution of the Universe, supernovae explosions, and X-ray emission from the centre of the galaxy.

Auditors with the US Government delivered a negative report this week about NASA's ability to properly estimate large projects, and manage them effectively. As part of this study, the General Accounting Office reviewed 27 programs, 10 of them in-depth, and came to the conclusion that "NASA lacks a clear understanding of how much programs will cost and how long they will take to achieve their objectives". In an appendix of the report, however, NASA acknowledged the flaws and detailed the steps it was taking to correct the situation.

Here's another picture for your Mars wallpaper collection. This time it's a 1024x768 image of a canyon on Mars called Valles Marineris, taken by the European Space Agency's Mars Express spacecraft. The full image was taken at a resolution of 16-metres per pixel. The image gives some clues about how such a dramatic surface feature developed, including some traces of volcanic activity and possible water-related activity. It's a heavily weathered part of Mars, however, so a lot has been obscured over hundreds of millions of years.

Cassini has turned to look at another of Saturn's moons; this time it's Iapetus. This image was taken on May 23, 2004, when Cassini was 20.2 million kilometres (12.5 million miles) from Iapetus. Although it's small and hazy in this picture, the moon is much larger than Phoebe, and measures 1436 km (892 miles) across. It was first photographed up close by the Voyager spacecraft, which found that it has a light and a dark side - this duality is just barely visible in this image.

Scientists have discovered that the currents in the Earth's oceans bear a striking resemblance to the bands of clouds in Jupiter's atmosphere. The clouds on Jupiter and the other gas giant planets form into bands which move in alternating directions from top to bottom. The similarity is more than coincidental, as both phenomena seem to be based on similar physical forces. This discovery could have implications in both climate research here on Earth, and the design of new space missions to explore the outer planets.

Radio astronomers have discovered two molecules never before seen in space in an interstellar cloud near the centre of the Milky Way. So far, about 130 different molecules have been found in space, but they usually contain only a few atoms each. These newly discovered molecules, propanal and propenal, have 8 and 10 atoms respectively. By finding complex molecules like this in space, scientists can get a better idea of the starting materials that Earth had to work with when it formed billions of years ago, and how life could have evolved.

Designed to test two of Einstein's predictions about the nature of gravity and relativity, NASA's Gravity Probe B spacecraft is about halfway through the initialization and checkout phase of its mission. Mission operators have transmitted more than 5,000 commands to the spacecraft, and everything seems to be functioning properly, including its gyroscopes and the targeting system that keeps it locked onto the guide star: IM Pegasi. If everything continues to go as planned, it should begin scientific operations in August, and deliver the final results in a year.

History was made today when test pilot Mike Melvill became the first private citizen to get his astronaut wings today when he flew Scaled Composites' SpaceShipOne (SS1) into space, reaching an altitude of more than 100 km (62.5 miles).

The European Space Agency's Rosetta spacecraft snapped this self portrait recently as part of a series of tests of the CIVA camera system on the Philae lander. In the picture you can see the back of Rosetta's solar panels and some of the spacecraft's body at the lower right. The CIVA imaging camera system consists of six identical micro cameras which will take panoramic photos of Comet Churyumov-Gerasimenko when it arrives in 10 years. This picture was taken when Rosetta was 35 million km (21.7 million miles) from Earth.

The newest image from NASA's Cassini spacecraft was taken on May 18, and shows beautiful swirling clouds in Saturn's southern hemisphere. This image was taken with the spacecraft's narrow angle camera at a distance of 23.4 million km (14.5 million miles) using a special filter that's sensitive to the absorption and scattering of sunlight from methane gas in the infrared spectrum.

NASA scientists coined the term "blueberries" to describe the tiny hematite balls found on Mars by Spirit and Opportunity over the last few months - it was one of the most powerful pieces of evidence that liquid water once flowed across the surface of Mars. Researchers from the University of Utah had a hunch these hematite concretions would turn up on the Red Planet, since there are similar conditions in Utah's national parks. The geologists believe the blueberries on Earth were formed 25 million years ago when minerals precipitated from groundwater flowing through sandstone.

A Russian-built Proton rocket successfully launched an Intelsat 10-02 communications satellite today from the Baikonur Cosmodrome in Kazahkstan. The rocket lifted off on Thursday at 2227 UTC (6:27 am EDT), and began the 9-hour journey to reach geosynchronous orbit. When it begins operations in August, the Intelsat 10-02 satellite will provide television, data and other telecommunication services to Europe, Africa and the Middle East.

All eyes will be on Mojave next week to see if Burt Rutan's SpaceShipOne can reach 100km (62 miles) of altitude, but another team in Texas could be hot on their heels. Armadillo Aerospace's John Carmack reported that a prototype of his team's rocket completed a successful test flight this week. The rocket lifted off from the launch pad, flew to a height of 40 metres (131 feet), and then returned to within less than 0.3 metres (1 foot) of its starting position. Carmack isn't sure his team will be able to meet the deadline to win the $10 million Ansari X Prize, but they may push to make an attempt if Rutan's team fails.

The latest image from Cassini shows four dark turbulent storms in Saturn's southern hemisphere. Storms like this are short lived, and will often merge together, or spawn new storms. This image was taken over a month ago, on May 15, when the spacecraft was 24.7 million km (15.3 million miles) away from Saturn. Cassini will arrive at Saturn at the end of June.

The Canadian-built MOST space telescope has shed new light on how stars like our own Sun can actually be quite turbulent, vibrating and flaring up unexpectedly. MOST tracked a star called eta Bootis for 28 straight days without interruption, and measured its brightness more than 250,000 times - 10 times more accurately than any previous instrument could reach. MOST should also assist planet hunters by watching how a star brightens and dims as planets pass in front of it, similar to Venus' recent transit across the face of the Sun.

After a long journey across rough terrain, NASA's Spirit Rover has finally reached the base of the Columbia Hills. It didn't wait long, though, and began climbing up the 90-metre (300 foot) high hills late last week. Scientists have identified several interesting rocks they'd like to study, including ones which look like they're disintegrating from the inside out, leaving a remnant "shell". Spirit is starting to show signs of wear; its right front wheel is slightly malfunctioning, and drawing much more power than the other wheels.

Where did the world's oceans come from? Some scientists believe all that water was originally locked into rocks, and slowly leaked out over millions of years. Others believe it was delivered from space by comets crashing into our planet. The European Space Agency's Rosetta spacecraft might help find the answer. When it reaches Comet 67P/Churyumov-Gerasimenko, Rosetta will send down a small lander, Ptolemy, that will measure the chemical signature of the comet's water, and see if that matches our water.

Cassini hasn't just been focused on Phoebe; it's also turned its camera on Titan, Saturn's largest moon. This image of the mysterious, cloud covered moon was taken on May 22, when the spacecraft was 21.7 million km (13.5 million miles) away. The northern hemisphere is much brighter than the southern hemisphere, which is the exact opposite situation that the Voyager spacecraft saw when they flew by 23 years ago, and it indicates the moon in the opposite season.

Using a combination of ground and space-based telescopes, an international team of astronomers have measured the mass of an ultra-cool star and its companion brown dwarf. The star is located 40 light-years away, and contains only 8.5% the mass of the Sun. Its companion brown dwarf is even lighter; only 6% the mass of the Sun. They orbit one another at a distance of only 2.5 times the distance of the Earth and the Sun. Measuring these low mass objects is difficult because there's no relation between their size and brightness. But in a binary system like this, astronomers can determine their mass by measuring how the objects interact with each other.

Cassini made its closest approach to Saturn's moon Phoebe on June 11, and the pictures are in. This photo is a skyline view of Phoebe that shows how the darker surface has been swept away in some areas to reveal the brighter material underneath. Scientists will be analyzing these pictures for years to try and understand the mechanism at work here. The large crater in this picture is 45 km (28 miles) in diameter, and the rim shows the greatest amount of this streaking.

This incredibly detailed image of Phoebe was taken when Cassini was only 12,000 km (7,400 miles) away from the small moon. It shows a 13-km (8-mile) diameter crater with building-sized rocks and other debris on its floor. There are additional craters visible in the image as well. The moon is generally very dark in colouration, but the brighter spots were probably caused by small meteorites that excavated the dark surface to show the lighter coloured ice below. Images that were taken when the spacecraft was even closer to Phoebe are still coming.

NASA's Cassini spacecraft made its first close encounter with the Saturnian system on June 11 when it swept past Phoebe. The spacecraft got as close as 2,000 km (1,240 miles) to the small moon, and saw incredible details on its smashed up surface. The evidence is starting to show that Phoebe may be an ice-rich body coated with a thin layer of dark material. Instruments on board Cassini will measure the moon's density to get a better sense about how much of it is composed of ice. Cassini will reach Saturn on June 30.

A global team of radio astronomers think they might have found the youngest black hole or neutron star approximately 30 million light-years from Earth. A supernova in exactly the same location was found to have exploded some time around 1983, and subsequent observations have found a brightly-emitting object at the very centre of the supernova remnant. They still can't tell if it's actually a black hole, or just a neutron star or pulsar, so further measurements will be required.

NASA's Cassini spacecraft is set to make its first and only flyby of Saturn's moon Phoebe on Friday at 2056 UTC (4:56 pm EDT). The tiny moon is only 220 km (137 miles) across, and Cassini will get within 2,000 kilometres (1,240 miles). This picture was taken on June 10 - one day before its closest encounter - when Cassini was still 658,000 kilometres (409,000 miles) away, so the resolution of the image is going to get much much better. Cassini will reach Saturn at the end of the month.

When Galileo went past Jupiter's moon Io, it found parts of it reached temperatures as high as 1,610 degrees Celsius (2,910 Fahrenheit). The moon is so hot because it's continually being squeezed by Jupiter's immense gravity - the friction from the tidal interaction keeps it warm. Observations from Galileo and Earth-based telescopes have seen that the volcanoes are so hot they're vapourizing sodium, potassium, silicon and iron into the moon's atmosphere.

Here's a 1024x768 wallpaper of a region of Mars called Mangala Valles taken by the ESA's Mars Express spacecraft. The region is located on the southwest Tharsis Bulge, and it looks like it was significantly shaped by liquid water some time in the distant past. Similar regions are here on Earth, where volcanic activity causes underground water and ice to suddenly burst forth in a catastrophic flood. In addition to the large outflow channels, there are smaller ones off to the side that could have been caused by rainfall.

The 8-metre Gemini South telescope has been coated with pure silver to give it more resolution when viewing objects in the infrared spectrum. A total of only 50 grams (2 ounces) of the precious metal were required to coat the entire glass mirror, which had previously been covered with aluminum. It didn't require much silver, but it was extremely difficult to apply. Workers used devices called magnetrons which surround a pure metal bar with a cloud of gas which knocks atoms of silver and allows them to deposit on the mirror at a perfect thickness of 0.1 microns (1/200th the thickness of a human hair).

Astronomers have used the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite to detect molecular nitrogen in interstellar space. Nitrogen is common in the Earth's atmosphere, and believed to be the fifth most abundant chemical in the Universe, but astronomers hadn't been able to find it in interstellar molecular clouds, where it's believed to be very common. This discovery should help astronomers better understand the formation of stars and planets out of clouds of dust and gas.

The European Space Agency has decided on how it will contribute to the construction of the next generation James Webb Space Telescope (JWST), due for launch in 2011. The Europeans will work with the USA on the Mid-Infrared Instrument (MIRI), which is one of four instruments on board JWST. MIRI will be used to study old and distant stellar populations, dust obscured regions of star formation, and comets and Kuiper Belt objects. JWST will be three times larger than Hubble and be able to resolve objects 10 to 100,000 times better depending on the wavelength and type of observation.

Since its existence was first theorized in the 1960s, scientists have been searching for the mysterious Higgs boson. This subatomic particle is believed to be responsible for mass, and would help explain why objects feel inertia and have momentum. Unfortunately, physicists were unable to find the particle in the 1990s using the world's largest atom smashers. A new estimate for the particle's mass from Berkeley Lab explains why it might have eluded discovery. Fortunately, CERN's new Large Hadron Collider, due to start up in 2007 should have the ability to find the Higgs particle at a heavier mass.

Now only three weeks from entering orbit around Saturn, it's time for Cassini to begin making some close up observations. Its first target is the tiny moon Phoebe, which is only 220 kilometres (137 miles) across. The images are already better than anything taken by Voyager 2, and show a varied surface, with mountains and craters. Cassini will get its best view on June 11 when it zooms past the moon at a distance of only 2,000 kilometres (1,240 miles). It should have enough resolution at the point to see objects the size of office buildings.

Scheduled for launch in 2006, the New Horizons mission will finally get a close up view of Pluto, the only planet never visited by spacecraft. On board the robotic spacecraft will be the Solar Wind Around Pluto (SWAP) instrument, which will measure the interactions between Pluto and the high-speed stream of particles flowing out from the Sun called the solar wind. Since it'll be so far from the Sun, SWAP will be largest aperture device ever built to measure the solar wind. It'll have lots of time to measure; the trip to Pluto will take 9 years.