Science and Space

space and astronomy articles.

Who Links Here

Comet photos

Click here to see spacecraft-views of comets, whose cores consist of raw materials from the disk that formed the Sun and planets billions of years ago.

posted by: kyawoo at 22:47 | link | comments |
comets

An asteroid belt found around a sunlike star

Scientists have for the first time found evidence for a massive asteroid belt around a mature, sunlike star, thanks to the Spitzer Space Telescope.

The star, dubbed HD69830, is some 41 light-years away—which, in space terms, is practically our own backyard.

Asteroids are the leftover building blocks of rocky planets like Earth. Scientists are interested in asteroid belts because they may mark either the construction sites that accompany the formation of rocky planets, the junkyards that remain after the formation of such planets, or simply places where, for one reason or another, material just couldn’t assemble to form planets at all. Asteroids occassionally collide with each other, raising cosmic dust. They also crash into planets and moons.

Of the 85 stars Spitzer scientists have examined to date, only HD69830 yielded evidence of an asteroid belt. It is thicker than the asteroid belt in our own solar system, which lies between Mars and Jupiter and packs nearly 25 times more debris.

Astronomers have previously detected other asteroid belts around two far younger, more massive suns. But researchers believe the latest discovery—an asteroid belt arrayed around a mature star—will reveal more about our sun and whether our solar system is the norm or the exception.

Scientists say they don’t know yet if any planets orbit HD69830.

posted by: kyawoo at 22:24 | link | comments |
unmanned missions, asteroids

Voyager 1 on the cusp of deep space

Voyager 1 spacecraft, launched in 1977, is now some 14 billion km (8.7 billion miles) from the Sun and on the cusp of deep space.

Nasa scientists told a conference in New Orleans on Tuesday that Voyager was moving through a region known as the heliosheath. This is a vast, turbulent expanse where the Sun’s influence ends and particles blown off its surface crash into the thin gas that drifts between the stars. Soon the probe will break into deep space.

Voyager 1 was initially given a mission life of five years but has continued to perform spectacularly.

The craft is carrying a time capsule in the form of a golden gramophone record, complete with stylus, which contains a recording of greetings from Earth in different languages as well as samples of music ranging from Mozart to singer Blind Willie Johnson.

Its twin, Voyager 2, launched a couple of weeks before Voyager 1, is moving on a different trajectory and is some 10.4 billion km (6.5 billion miles) away.

posted by: kyawoo at 08:16 | link | comments |
unmanned missions

Close earth fly-by of asteroid 2004 MN4 on Friday the 13th - 2029

Friday the 13th is supposed to be an unlucky day. But on April 13th - Friday the 13th - 2029, millions of people are going to go outside, look up and marvel at their good luck. asteroid 2004 MN4 will be gliding across the sky, faster than many satellites, brighter than most stars.

What’s so lucky about that? The asteroid is not hitting Earth. It is about 320 meters wide. That’s big enough to punch through Earth’s atmosphere, devastating a region the size of, say, Texas, if it hit land, or causing widespread tsunamis if it hit ocean.

Asteroid 2004 MN4 had been discovered in June 2004.

Asteroid 2004 MN4 will fly past Earth only 18,600 miles (30,000 km) above the ground. For comparison, geosynchronous satellites orbit at 22,300 miles (36,000 km). At closest approach, the asteroid will be visible to the unaided eye from Africa, Europe and Asia. Close approaches by objects as large as 2004 MN4 are currently thought to occur at 1000-year intervals, on average.

posted by: kyawoo at 13:13 | link | comments (1) |
asteroids

Spacecraft circling Mars takes pictures of fellow orbiters

Mars Odyssey Seen by Mars Global Surveyor

Mars Express Seen by Mars Global Surveyor

The images taken by NASA’s Mars Global Surveyor show NASA’s Mars Odyssey and the European Space Agency’s Mars Express. The images mark the first time a spacecraft orbiting another planet has taken pictures of other spacecraft orbiting the same planet.

Mars Global Surveyor’s camera photographed Mars Express from a distance of about 155 miles on April 20 and the next day took a picture of Mars Odyssey at a distance of 56 to 84 miles.

Mars Global Surveyor has been orbiting Mars since 1997 and Mars Odyssey since 2001. Mars Express reached the planet in 2003.

posted by: kyawoo at 10:02 | link | comments |

Tiny moon in Saturn's ring

Cassini spacecraft took a series of snapshots of a Saturn moon on May 1. A day later Cassini took an even closer picture of the moon that allowed scientists to estimate both its size and brightness.

The moon, identified for now as S/2005 S1, is about 7 kilometers (4 miles) across and reflects about half of the light that hits it as it orbits about 137,000 kilometers (85,000 miles) from the center of Saturn, scientists said.

The small moon is located about 250 kilometers (155 miles) inside the outer edge of Saturn’s bright main rings in an area known as the Keeler gap.

Another Saturnian moon, Pan, also orbits the planet from within its rings and scientists believe there may be many others.

posted by: kyawoo at 22:18 | link | comments |
saturn

Titan's secrets revealed

Thanks to the Cassini spacecraft and the Huygens probe, scientists are unearthing the secrets of Satuirn's mysterious moon — Titan. NASA’s Cassini first flew past Titan in October last year, providing close-up radar images of the moon’s cloud- shrouded surface. On January 14 the European Space Agency’s Huygens probe (which was deployed from the Cassini oribiter) landed successfully on Titan.

Scientists realized that Titan is a very complex place, really a planet in its own right that happens to be in orbit around another planet.

The nitrogen and methane in Titan’s atmosphere combine into long chains of hydrocarbons. For nearly two decades scientists had theorized that these hydrocarbons would condense and rain onto Titan’s surface, perhaps creating methane lakes or liquid- filled craters. Cassini has altered such theories. Liquid lakes are not seen on Titan. Scientists are now thinking that regions of liquid will be fairly confined if they find them at all. A new hypothesis likens Titan’s rain cycle to that of a frigid Arizona, where occasional methane precipitation carves riverbeds that are dry during most of the year.

On Titan, processes seen on Earth, like windswept surfaces and streams carved by liquid, are present but are played out with different materials.

Researchers expected the moon to be dotted with craters, but only two have been spotted so far, indicating that there are active geological processes which are erasing surface features.

Volcanism is one such process that may well be at work. But on frigid Titan it involves not lava but water-ice-based "cryolava." If you add something like ammonia to water you get a much colder melting point, a molasses-like texture, and a more buoyant liquid that will periodically come out [of cracks or other fissures in the icy surface]. These "cryovolcanic" processes may be at working shaping and reshaping Titan’s surface, in much the same way that hot volcanic activity does on Earth.

Specific atmospheric traits are also emerging from the Cassini data. Titan’s winter polar atmosphere may have interesting parallels with Earth’s Antarctic ozone hole—albeit with different chemistry.

Infrared images reveal frigid temperatures (-290 degrees Fahrenheit, -180 degrees Celsius) circumpolar winds up to 358 miles per hour (576 kilometers per hour), and polar concentrations of atmospheric organic compounds that are different from those of other latitudes.

posted by: kyawoo at 12:32 | link | comments |
saturn

Sharpest ever Earth map

The most detailed portrait ever of the Earth’s land surface is being created with ESA’s Envisat environmental satellite. The GLOBCOVER project aims at producing a global land cover map to a resolution three times sharper than any previous satellite map.

It will be a unique depiction of the face of our planet in 2005, broken down into more than 20 separate land cover classes. The completed GLOBCOVER map will have numerous uses, including plotting worldwide land use trends, studying natural and managed ecosystems and modelling climate change extent and impacts. The estimate is that up to 20 terabytes of imagery will be needed to mosaic together the final worldwide GLOBCOVER map – an amount of data equivalent to the contents of 20 million books.

The GLOBCOVER project was launched 2004 as an initiative of ESA which is now evolving to an international collaboration.

posted by: kyawoo at 13:11 | link | comments |
earth

Was Phoebe, Saturn’s pock-marked moon, a comet?

Saturn’s pock-marked moon Phoebe("FEE bee") could be a comet that was captured by the gravity of the ringed planet according to the scientists at German Aerospace Center (DLR).

Judging hrom Phoebe’s eccentric, retrograde orbit and unusual albedo scientists have speculated long ago that it may be a captured comet which originated in Kuiper Belt.

Analysis of Phoebe’s surface shows that it is one of the most complex Solar System objects yet studied. Scientists have identified water-ice, possible clays, iron-bearing minerals and organics such as aromatic compounds, alkanes and nitriles on the 220 km-wide moon. Clays could have formed through heating if Phoebe came close to the Sun before being captured by Saturn, forcing water-ice to react with silicates.

The observations come from Cassini’s Visual and Infrared Mapping Spectrometer (Vims) during a close flyby on 11 June 2004.

Phoebe was discovered by William H. Pickering in 1898.

posted by: kyawoo at 23:58 | link | comments |
saturn

Saturn's new moons

U.S. astronomers have discovered 12 new moons orbiting Saturn. All the newly discovered moons are small, irregular bodies — probably only about 1 mile to 4 miles in diameter. They are distant from Saturn and each takes about two years to complete one orbit. All but one of these moons circles the ringed planet in the opposite direction to its larger moons.

The discoveries were made on December 12, 2004 using the 8.2-meter diameter Subaru telescope on Mauna Kea, Hawaii.

If confirmed, the new moons would bring Saturn’s count to 46. Jupiter, with 63, still has the most moons. Uranus has 27 and Neptune 13.

posted by: kyawoo at 21:43 | link | comments |
saturn