Engineers are still working to troubleshoot a malfunctioning fuel gauge on the space shuttle Discovery's external tank, but NASA has pinned down a launch date anyway. If all goes well, Discovery is expected to lift off on Tuesday, July 26 at 1439 UTC (10:39 am EDT). Even if the fuel sensor fails again, managers will go ahead with the launch, as they don't believe there's a risk to the shuttle - there are 3 additional sensors that perform the same task.

Supernovae are powerful stellar explosions that flare up brightly and then slowly fade away. But not always. One supernova, that exploded in 1979, is blazing as brightly in X-rays as it did when it was first discovered. The discovery was made using the ESA's XMM-Newton space telescope. Scientists speculate that a powerful solar wind is smashing into previously ejected material, heated it up until it glows brightly. This is like a powerful light illuminating the whole area, and allowing the astronomers to study the whole area for years and see how it changes over time.

Astronomers have used the massive Gemini and W.M. Keck observatories to discover a Sun-like star with one of the warmest, dustiest environments ever seen. The disk around star BD +20 307 is warmer than most other planetary disks because there have probably been recent collisions between planets. In fact the heat is so high, the researchers think a collision recently occurred that matches a cataclysmic event in the Earth's past when a Mars-sized object smashed into our planet, and spun off material that became the Moon.

Since scientists announced the discovery of methane in the atmosphere of Mars last year, there has been a controversy about whether this is an indication of life on the planet or not. Methane should only last a few hundred years in the Martian atmosphere before it breaks apart, so some source is continually producing it. On Earth, the main source of methane is from life; mainly microbes. But could there be some other natural geological process on Mars keeping this gas in the atmosphere?

NASA is targeting July 26, 2005 as the earliest date for the space shuttle Discovery to return to flight. Engineers are still working through a troubleshooting plan to get to the bottom of a problem with a liquid hydrogen low-level sensor circuit that forced managers to abort the launch last week. Discovery's launch window lasts until July 31, and then opens up again in September.

Astronomers from MIT and Williams College have teamed up to capture an event seen only once, 25 years ago. On the night of July 10/11, Pluto's moon Charon briefly passed in front of a distant star - this is called an occultation. By studying how the light from this star dimmed and then brightened again, the astronomers will be able to determine if Charon has an atmosphere. Charon is small, so it doesn't have much gravity to hold an atmosphere, but it's so cold that some gasses could be held in place.

Observations with the Chandra X-Ray Observatory have given astronomers some clues about what causes millisecond pulsars - extremely dense stars which can spin many times a second. Several of these pulsars were discovered in a stellar cluster called 47 Tucanae, where the stars are less than .1 light years apart. Astronomers think these pulsars started as regular neutron stars, but tightly joined with stellar companions they picked up in the cluster. Eventually they get so close they start drawing material off the companion, which causes them to speed up.

On December 27, 2004, a neutron star flared up so brightly, it temporarily blinded all the X-ray satellites in space for an instant, and lit up the Earth's upper atmosphere. This tremendous blast of energy was from a giant flare created by the neutron star's twisting magnetic field. Objects like this are called magnetars, and they produce magnetic fields trillions of time more powerful than those here on Earth. These fields are so strong they can actually buckle the surface of the neutron star causing these powerful star quakes.

Astronomers from the Harvard-Smithsonian Center for Astrophysics have found a dusty disk around a star which is 25 million years old. Planetary disks like this have been seen before, but never around a star which is so old; it's possible it'll never form planets. Most planetary disks make the transition within just a few million years, and the previous record was 10 million years. The disk still has a lot of gas in it, so researchers think it's still possible that it could form gas giants.

Scientists can tell us what our climate on Earth was like in past by examining ice cores taken from glaciers. Tiny bubbles of air are trapped in the ice and maintain a historical record of ancient atmospheres. The effects of life make their mark in these ice samples as well. What if you examined the icecaps on Mars, or the layers of ice on Europa? NASA is considering a proposal for a small spacecraft that would land on Mars or Europa and melt its way throught the ice, collecting data as it descended, searching for clues about the presence of life.

When humans first step onto the surface of Mars in the coming decades, they'll be like kids in a candy store; so many rocks to turn over or chip away at. Is that discoloured patch algae? A team of Spanish engineers are working on a Cyborg Astrobiologist that could help observe the landscape with a video camera, see what the astronauts see, and suggest places that might be interesting for further study. Larry Klaes reports on this interesting new technology, but he thinks robots could use a system like this even sooner.

NASA's Cassini spacecraft took this picture of Saturn with its moon Tethys in the foreground. Tethys is 1,071 (665 miles) across. Cassini took this image on June 10, 2005 when it was approximately 1.4 million km (900,000 miles) away from Saturn.

Space Shuttle managers have announced that Discovery won't be lifting off until late next week, at the earliest. Engineers and managers are still trying to troubleshoot exactly what caused a problem with the external tank's fuel gauge. It's possible that one of the new safety improvements, implemented as part of the Return to Flight effort might be causing the glitch. If the shuttle doesn't launch by July 31, it will need to wait again until September before there's another opportunity.

One of the more productive telescopes in space is the tiny Canadian MOST satellite (Microvariability and Oscillations of Stars). Developed and maintained on a shoestring - $7 million USD - MOST is only the size of a suitcase, but it has a very sensitive instrument which can detect the variations in star brightness. MOST has been used to analyze recently discovered extrasolar planets as they pass in front of their parent stars, and even get some information about their atmospheres.

Greetings, fellow SkyWatchers! We'll begin this week by watching the dance of Venus and viewing beautiful star system Omicron Cygni. Although the Moon goes full this week, we can still take pleasure in exploring its bright ray systems. Need more? Then let's have a look at Epsilon Lyrae and 61 Cygni. Simply stargazing during the warm summer nights can bring its own rewards, for the Aquarid meteor shower is highly active. So turn your eyes to the skies, because...

Here's what's up!

Some children do grow up and become space travellers. Along the way a series of powerful experiences may act as propellants, advancing them into the future. Winston Scott in his book Reflections from Earth Orbit warmly expresses his memories, from watching Saturday morning cartoons with his brother to undertaking EVA's with NASA colleagues. This sharing of his experiences and personal highlights allows an inside look into one person's advancement into space travel.

In this nearly side-view of Saturn's rings, it's possible to see the two ring shepherd moons: Pandora (right) and Prometheus (left). Saturn's F ring extends out to the far right, and contains a large amount of fine, icy material that is probably the size of dust, unlike the B ring which has boulder-sized objects in it. This picture was taken when Cassini was 1.85 million km (1.15 million miles) away from Saturn.

During a recent flyby of Titan, Saturn's largest moon, NASA's Cassini spacecraft got a good look at the bright Xanadu region - where the Huygens probe landed earlier this year. One unusual feature is the strange bright line, which scientists are calling the "smile". This 560 km (345 mile) long feature is quite bright in several of Cassini's instruments; in both visible and infrared wavelengths. It's exact nature is still unknown, so scientists will continue to gather evidence from future flybys.

The Atacama Pathfinder Experiment (APEX) achieved a new milestone this week when it made its first observations. APEX consists of a 12-metre telescope designed to view the Universe at submillimeter wavelengths: a part of the radio spectrum especially useful for viewing colder objects. APEX is the same instrument that will eventually go into the much larger ALMA project, which will consist of at least 64 of these telescopes, arrayed to function as a single instrument.