Space & Astronomy

Solar storms, like a big one that affected Earth last year, might have torn away the water that used to cover parts of Mars, NASA scientists said on Thursday. Astronomers believe Mars once had oceans of surface water, enough to support long-ago life, but they have not determined where that water went some 3.5 billion years ago. Now researchers monitoring the after-effects of a monster solar storm that hit Earth in October and November 2003 said they think repeated buffeting by this kind of space weather could have ripped away Mars' watery veil. "These (solar) radiation events can affect the surface of Mars because Mars has so littleprotection," said Ed Stone of NASA's Jet Propulsion Laboratory in Pasadena, California.

Unlike Earth, which has a protective magnetosphere that guards the planet against bombardment by high-energy particles during a solar storm, Mars has only isolated zones of protection, astronomers said in a telephone-and-Internet briefing. Observations by the Mars rovers Spirit and Opportunity have bolstered the idea of plentiful Martian water, according to Thomas Zurbuchen of the University of Michigan at Ann Arbor. "Where did it go?" Zurbuchen asked rhetorically about Mars' water. "One of the key ideas that people are talking about is the connection to these space storms ... Over 3.5 billion years, there's kind of agradual erosion of this water." The astronomers referred to a video simulation of what might have happened on Mars, available online at http://www.gsfc.nasa.gov/topstore/2004/0708flare1.htm. The brief video, Movie 4 at the Web site, showed water seemingly blowing away from the planet. Scientists worked with a small fleet of robotic spacecraft to watch the impact of last year's "Halloween" solar storm, the most powerful ever monitored. Starting with the SOHO spacecraft which monitors the sun from its vantage point near Earth, the astronomers also tracked the solar blast wave with the Ulysses craft near Jupiter and the Cassini craft that justbegan orbiting Saturn....

China aims to send a spacecraft to the Moon in three years' time, the head of the country's space agency, Sun Laiyan, has confirmed to the BBC. In a wide-ranging interview, Mr Sun outlined the next steps China would take in expanding its space efforts. These included unmanned missions from 2007 to orbit and land on the Moon, and to build a Chinese space station. Mr Sun said China was happy to work with other nations, including the US, in space but only on an equal footing. He made his comments to the BBC World Service in one of the first interviews he has given to the western media since taking up his post as the chief administrator at theChina National Space Administration (CNSA) in April.

In the discussion, Mr Sun made no secret of China's ambition to become the next space superpower. The Moon was a major target, he said, and the first mission should take place before Beijing hosts the Olympic Games in four years' time. "First, we'll try to send an unmanned spacecraft there in 2007," he explained. "That's the first step... [The] second step is to send an unmanned craft to land on the Moon and move around and send back data. [The] 3rd step is taking samples and coming back to Earth. All these [missions] will be unmanned." Western analysts believe China currently has rockets capable of sending craft to the Moon and back but it wouldneed more powerful boosters for landings. The next few years will also see more Chinese astronauts, or yuhangyuan, launched into Earth orbit, following the path taken last October by Yang Liwei. Some of these space people will be women. "It's a very important reason for gender equality," Mr Sun said. "We have a lot of excellent female engineers, so if they're fit they could qualify." The CNSA chief said China was serious about establishing an orbiting space station and laboratory but he gave no timescale. The US has blocked China from participating in the International Space Station, which may be one reason why China is prepared to build its own. "This space station was under construction for manyyears. ...

Saturn's rings are a a lot dirtier than originally believed, according to new observations by the Cassini spacecraft that show that the inner regions are packed with rock and mud. "We've known for decades the rings are mostly made of water," said Larry Esposito of the University of Colorado at Boulder. "Now we know the amount of water varies, increasing toward the outer edge of the rings. Cassini images made in ultraviolet light and released yesterday have been combined with infrared pictures -- all taken during the June 30 pass through the ring plane -- to give scientists a fresh but still puzzling picture of the majesticstructures.

Scientists don't know how the rings formed. One idea is that an icy object from the outer solar system was lured in close and broken apart by Saturn's impressive gravity. The new data are not conclusive, but they can be read to support that theory. The ice in the rings is "like gunk in a skating rink," Esposito told SPACE.com . He described it also as being like mud. Nobody knows what the gunk is made of, he explained, but it is likely silicates and organic material, the stuff of rocks and dirt on Earth. The ice is also thought to contain water mixed with other frozen substances such as ammonia. Cassini's cameras were not powerful enough to resolve the individual icy boulders and smaller particles thoughtto make up the rings. The new ultraviolet (UV) observations were compared with similar observations made in laboratories, where researchers determined how much UV light would be reflected by water versus other material. Esposito stressed that the new observations are not surprising. But he said they are the most detailed ever made in UV and infrared, providing data that will be chewed on for some time. Meanwhile, the differing concentrations of dirt and water might tell something of the rings' origins and evolution. BombardmentEsposito thinks the rings formed long ago as icy material that has since been bombarded by dark stuff from meteors. The darker material might be more diluted where ice concentrations are higher, hesaid.Saturn's. ...

A new analysis shows that the Sun is more active now than it has been at anytime in the previous 1,000 years. Scientists based at the Institute for Astronomy in Zurich used ice cores from Greenland to construct a picture of our star's activity in the past. They say that over the last century the number of sunspots rose at the same time that the Earth's climate became steadily warmer. This trend is being amplified by gases from fossil fuel burning, they argue. Sunspots have been monitored on the Sun since 1610, shortly after the invention of the telescope. They provide the longest-running direct measurement of our star'sactivity.

The variation in sunspot numbers has revealed the Sun's 11-year cycle of activity as well as other, longer-term changes. In particular, it has been noted that between about 1645 and 1715, few sunspots were seen on the Sun's surface. This period is called the Maunder Minimum after the English astronomer who studied it. It coincided with a spell of prolonged cold weather often referred to as the "Little Ice Age". Solar scientists strongly suspect there is a link between the two events - but the exact mechanism remains elusive. Over the past few thousand years there is evidence of earlier Maunder-like coolings in the Earth's climate - indicated by tree-ring measurements that show slow growth due toprolonged cold. In an attempt to determine what happened to sunspots during these other cold periods, Dr Sami Solanki and colleagues have looked at concentrations of a form, or isotope, of beryllium in ice cores from Greenland. The isotope is created by cosmic rays - high-energy particles from the depths of the galaxy. The flux of cosmic rays reaching the Earth's surface is modulated by the strength of the solar wind, the charged particles that stream away from the Sun's surface. And since the strength of the solar wind varies over the sunspot cycle, the amount of beryllium in the ice at a time in the past can therefore be used to infer the state of the Sun and, roughly, the number of sunspots. Latest warming Dr Solanki ispresenting a. ...