Could microbes survive on Mars? Along with microbiologists at the University of Maryland, astronomers from the Space Telescope Science Institute have been studying how microbes adapt to frigid temperatures by clustering together to protect each other from the cold. It's good news for the Hubble Space Telescope - NASA has decided to launch another servicing mission to repair and update the telescope. Four previous servicing missions have kept Hubble at peak performance, but the last one was canceled after the Columbia shuttle disaster in 2003. In addition to fixing degraded components, astronauts will provide Hubble with a new camera and other instruments to make it more powerful than ever.
A mission to Mars would be fraught with difficulties. For instance, the intense radiation of the Sun could cause long-term damage to the astronauts who would have to travel for months to reach the distant planet. Now a student at the University of Arizona has come up with a unique way of using asteroids to shield astronauts from this dangerous radiation. Daniella Della-Guistina of the University of Arizona won a NASA Institute for Advanced Concepts fellowship to study the concept.
Astronomers are trying to understand the true nature of "dark energy," the repulsive force that appears to be accelerating the expansion of the universe. Some of the questions: has dark energy always been around? Has it been consistent in its behavior? With the Hubble Space Telescope researchers have been able to find very distant supernovae similar to the nearby supernovae used to measure the acceleration. These distant supernovae indicate that the acceleration was present in the early universe, and the rate of acceleration is consistent with what would be expected from dark energy.
Globular clusters, groups of hundreds of thousands of stars held together by gravity, formed in the early universe. Astronomers have predicted that, due to the force of gravity over millions of years, the most massive stars would migrate to the center of the cluster, while the "lighter" stars would drift to the outer parts. The Hubble Space Telescope recently discovered evidence that this theory was true by measuring the speed of stars in 47 Tucanae - one of the densest globular clusters in the Southern hemisphere.
Titan is the largest moon orbiting Saturn. New images from the Cassini spacecraft show the frigid moon has features very similar to some on Earth. The new radar images show a bright region about the size of Australia, called Xanadu. Discovered by the Hubble Space Telescope in 1994, Xanadu is surrounded by dark terrain and contains sand dunes, hills, valleys and possibly even rivers and lakes.
Hubble captured an eclipse on Uranus, as the icy moon Ariel cast its shadow onto the planet?s cloudy atmosphere. It?s the first such eclipse viewed. Uranus orbits the Sun so slowly that a single season lasts 42 years. On the opposite end of the spectrum, Hubble found a planet that orbits its star every 10 hours. The Jupiter-size planet, 3000 degrees Fahrenheit in temperature, is extremely close to its star. Hubble has found a rare example of a galaxy under construction. A recent image shows a group of smaller galaxies merging into a massive galaxy over 10 billion years away. Astronomers believe this is how today?s galaxies formed.
The expansion rate and scale of the universe are fundamental quantities that astronomers strive to nail down. As of 2001, the expansion rate of the universe, and therefore the distance scale, was pretty well determined. New observations of a binary star system in a nearby galaxy, M33, has highlighted the difficulty of measuring vast distances. The stars' dimness indicates that the system is 15 percent farther away than expected - about 3 million light-years away, instead of 2.6 million light-years. The discovery could call into question the rate of expansion of the universe, known as the Hubble constant. If the new analysis survives the test of time, it could be that the universe is 15% larger and older than previously thought.
The United States space policy recently underwent a somewhat controversial revision. The new Bush administration policy stresses protecting US interests in space and denying "freedom of action" in space to adversaries. The policy says "freedom of action in space" is as important as air power and sea power to the United States. The policy also supports the administration's previously stated Moon and Mars agenda, as well as such traditional concerns as space debris, but some are concerned that the new policy will fuel other countries' suspicions that the US intends to leave the door open for placing weaponry in space.
Astronomers studying two of Hubble?s deepest views of the universe have discovered 500 dwarf galaxies that existed when the universe was about a billion years old. These tiny galaxies have unusual rates of star formation, making stars 10 times faster than the galaxies we see today. Astronomers think the radiation from these furiously active galaxies may have led to the re-heating of the cold hydrogen gas that existed between galaxies in the early universe, a major turning point in the evolution of the cosmos.
What would happen if astronauts traveling to the Moon or Mars were in need of serious medical attention? They might not be able to return to Earth in time for treatment. So recently a team of French surgeons performed the first zero-gravity surgery aboard a specially outfitted plane, removing a benign tumor from the arm of a volunteer. This is the first time such an operation has been carried out on human being. The chief surgeon said operation, conducted as the plane went through maneuvers meant to simulate the weightlessness of space, "went ahead without any particular difficulty."
Searching for planets, Hubble is finding strange, immense objects that fall in between planets and stars. Hubble recently found an object orbiting a red star that is about the size of Jupiter, but weighs 12 times more. The object could be a planet, or it could be a star that was unable to achieve fusion - an object also known as a brown dwarf. Hubble has uncovered a number of galaxies that existed less than a billion years after the Big Bang. Astronomers believe the new observations help show that galaxies grew from smaller star clusters that drew together and merged. Many of the galaxies are obvious around 900 million years after the Big Bang, but scientists can find very few only 200 million years earlier, indicating a lot of small-galaxy collision and merging during those 200 million years.
Nearly 2,000 years ago, Chinese astronomers spotted a new star in the night sky. This particular ?guest star,? as they were then called, was catalogued in Chinese records with its exact location noted. The star eventually faded over the eight months time. And now astronomers have found what they think is the remains of that exploded star, the oldest on record.
More and more planets! A recent Hubble Space Telescope survey of over 180,000 stars turned up 16 new planets, very far away from the Sun. These systems are about a quarter of the way across our Milky Way galaxy. The planets found are larger than Jupiter and orbit around their stars very quickly, very close to the star. Early planet searches involved looking for a ?wobble? in the motion of stars caused by large planets. A new technique is to look for the slight dimming of a star?s light caused by a planet passing, or ?transiting,? in front of the star. To use this technique, the orbit of the planet has to be just right, and the planet needs to be fairly large to block out enough light. The results of the search are good news for NASA?s Kepler Mission, which will search for smaller planets using the transit technique.
In the dusty center of the Milky Way lies the Quintuplet Cluster - five bright stars surrounded by hundreds of lesser stars. The cluster was discovered in 1990 by peering through the dust with infrared telescopes. Since then scientists have debated the character of this odd object - were the stars old or young, and how did they form? Scientists using the Keck Telescope - the largest optical telescope in the world - have taken a closer look at the cluster's brightest stars. They discovered that the stars are at the end of their lives and about to go supernova. The bright, massive stars burn through their fuel quickly, so they won't be terribly old when they finally explode. Scientists found spiral shapes around two of the stars in the cluster. The stars' mutual gravity pulls material from each other's atmosphere, causing fiery pinwheel shapes to form within the cluster. These spiral shapes are the size of our entire solar system.
When the Cassini-Huygens mission's Huygens probe landed in 2005 on Titan, Saturn's largest moon, it dropped into a puddle of mud. Titan experiences a constant drizzle of liquid methane. On Earth, methane is a flammable gas, but Titan has no oxygen in its atmosphere, preventing combustion. The frigid Titan temperatures of minus 300 degrees Fahrenheit (minus 148 degrees Celsius) allow the methane to pour down in liquid form from Titan's methane-nitrogen clouds.
Scientists have a theory about the size of stars. Stars must be about 80 times the mass of Jupiter in order to shine. It's the limit at which fusion can occur. Below that limit, scientists think, fusion occurs briefly before the object turns into a cool cinder called brown dwarf. New observations of nearby globular cluster NGC 6397 are helping confirm the theory. Globular clusters compact groups of stars are especially useful for this test since they contain hundreds to thousands of stars and are billions of years old. By studying the cluster until they found all the hydrogen-burning stars, scientists found the dimmest stars in the cluster, including the lowest-mass stars capable of sustaining fusion. The scientists also examined the burned out remains of stars that died long ago, called white dwarfs. In doing so, they discovered an effect that was predicted, but never witnessed. As a rule of thumb, the hottest stars are known to burn blue, while cooler stars burn red. The dimmest of the cluster's white dwarf stars have such low temperatures that they are undergoing a chemical change in their atmospheres that makes them appear bluer rather than redder as they cool.
Hubble has found the dimmest stars in the galaxy. The faint red dwarfs, about as bright as a birthday cake candle viewed on the Moon from Earth, are located in the ancient globular star cluster NGC 6397. Globular star clusters are compact groups of hundreds of thousands of stars. Dark matter has long been a mystery to astronomers. Now Hubble has helped astronomers find conclusive proof of the existence of dark matter. Hubble and the Chandra X-Ray Observatory found that dark matter and normal matter were wrenched apart by a collision of two clusters of galaxies. The observations showed that most of the matter in the galaxy cluster IE 0657-556 is separate from the normal matter. Most of the matter in the cluster, in fact, is dark matter. The complex and intricate structure of an exploded star is on display in one of Hubble?s latest pictures, an image of supernova remanant Cassiopeia A. The remnant is young - only about 340 years old - and Hubble has viewed it repeatedly to look for changes in the filaments of gas cast off in the initial explosion.
About 10,000 light years from Earth, embedded in heart of a "supernova remnant" the remains of an exploded star lies a stellar object unlike any ever seen in our galaxy. The object looks like a densely packed neutron star surrounded by a bubble of ejected stellar material, just what would be expected in wake of a supernova explosion. But observations by an orbiting x-ray satellite revealed a strange pattern of x-ray emissions. The object is less than 2,000 years old, but behaves like a neutron star that has been around for several million years old.
Pluto has lost its planet status, according to a recent decision by the International Astronomical Union (IAU). Before 1930, when Pluto was found, everyone knew there were only eight planets. Pluto was considered an oddball even at the time of its discovery. The solar system has four rocky planets - Mercury, Venus, Earth and Mars followed by four large, gaseous planets - Jupiter, Saturn, Uranus and Neptune. Astronomers expected any other planets further than that to also be gas giants. Instead they found Pluto, a tiny ball of ice with an odd orbit. Many astronomers now feel they simply made a mistake by classifying Pluto as a planet. The discovery of objects like Xena, very similar to Pluto, sharpened the debate. If Pluto had remained a planet, dozens of new planets might have been added to the solar system.
Recent evidence from X-ray telescopes reveals thousands of black holes in our galaxy and beyond. While many have formed in the collapse of massive stars, others are far more massive and contain millions to billions of times the mass of a single star. Scientists are still trying to understand how matter behaves around black holes.