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Comets may be made of same stuff

Scientists had thought comets fell into two distinct categories because of their vastly different orbits and what seemed to be different compositions.Now they see that the difference may really be just superficial, only skin deep. Astronomers from the Keck, Subaru and Gemini observatories reported their conclusions Friday in the journal Science.

Scientists had believed that comets such as Tempel 1, which regularly orbit past the sun, were different from the variety of comets believed to remain in a shell-like cloud of comets orbiting the sun called the Oort Cloud.

Analysis of the dust blasted from the interior of Tempel 1 - about 25 tractor-trailer trucks worth - shows it is made of much of the same matter as Oort Cloud comets, the astronomers wrote in Science.

The material included water, carbon-containing substances such as gas ethane, and silicates such as olivine - the same green mineral that makes up the Big Island’s Green Sands beach. It’s now likely that these bodies formed between the orbits of Jupiter and Neptune in a common nursery.

posted by: kyawoo at 06:02 | link | comments |
comets

NASA’s moon plan

NASA is to spend $100 billion to build the spacecraft and rockets it needs to put humans back on the Moon by 2018. NASA’s plan envisions landing four astronauts on the Moon for a seven-day stay.

The expedition would begin by launching the lunar lander and Earth departure stage on a heavy-lift launch vehicle that would be lifted into orbit by five space shuttle main engines and a pair of five-segment shuttle solid rocket boosters.

Once the Earth departure stage and lunar lander are safely in orbit, NASA would launch the Crew Exploration Vehicle capsule atop a new launcher built from a four-segment shuttle solid rocket booster and an upper stage powered by a single space shuttle main engine. The CEV would then dock with the lunar lander and Earth departure stage and begin its several day journey to the Moon.

NASA’s plan envisions being able to land four-person human crews anywhere on the Moon’s surface and to eventually use the system to transport crew members to and from a lunar outpost that it would consider building on the lunar south pole, according to the charts, because of the regions elevated quantities of hydrogen and possibly water ice.

NASA’s Crew Exploration Vehicle is expected to cost $5.5 billion to develop and the Crew Launch Vehicle another $4.5 billion. NASA’s plan also calls for using the Crew Exploration Vehicle, equipped with as many as six seats, to transport astronauts to and from the international space station. An unmanned version of the Crew Exploration Vehicle could be used to deliver a limited amount of cargo to the space station.

posted by: kyawoo at 21:11 | link | comments |
manned missions, moon

Spacecraft reached its target - an asteroid

Japan’s Hayabusa spacecraft has reached its target - asteroid Itokawa and the probe "parked" about 20 kilometres away from the asteroid on Monday.

The spacecraft will immediately start mapping the asteroid and will determine its surface composition by analysing the spectra of the light it reflects. At the end of September, it will approach to about 7 km from the 630-metre-long asteroid and make a more detailed map. Then in November 2005, Hayabusa will descend toward the asteroid’s surface and touch down twice. Each time, a fabric cone will touch the surface, triggering the firing of a pellet into the asteroid at 300 metres per second. After each firing, the probe will take off and attempt to collect the dust ejected from by the impact.

Launched on 9 May 2003, Hayabusa aims to be the first ever craft to bring pieces of an asteroid back to Earth.

Hayabusa is expected to return to Earth in June 2007. Once the asteroid samples reach the lab, scientists will analyse their composition and compare this to collections of meteorites that have fallen to Earth.

Another space mission, NASA’s Near Earth Asteroid Rendezvous (NEAR) visited the asteroid Eros in 2000 and found it to be fairly homogenous. That does not appear to be the case for Itokawa Early pictures of the asteroid appear to show hilly and rocky regions in addition to some very smooth features.

posted by: kyawoo at 01:08 | link | comments |
asteroids

New findings about Pluto and its moon Charon

A new colour map of Pluto is produced using images from the Hubble Space Telescope. The detailed map shows areas likely to be methane frost and a bright spot perhaps made of frozen carbon monoxide. The researchers have found dark areas thought to be dirty water-ice and brighter ones indicating nitrogen frost. Red areas indicate methane ice and possibly other organics (carbon-based molecules). The methane frost seems to be everywhere, running into dark and light areas on "a hemispheric level".

An accurate measurement of Charon’s radius and density were obtained from observations made during the moon’s occultation on 11 July 2005. It is calculated that the radius of Charon to 602.5km, plus or minus one kilometre - the most precise figure yet obtained for its size. From the new radius, scientists are able to determine a very accurate density for Charon of 1.73 (plus or minus 0.08) grams per cubic centimetre.

posted by: kyawoo at 02:28 | link | comments |
planets

Unmanned cargo ship docked at ISS

The unmanned Progress M-54 Russian cargo ship carrying food and supplies docked at the international space station Saturday.

The station’s two-man crew — Krikalev and U.S. astronaut John Phillips — will unload the nearly 2.8 tons of fuel, food and water, along with a replacement cartridge for the orbiter’s oxygen generator.

The crew is in its last month on the station. A two-man replacement crew is scheduled to head to the station October 1, along with an American scientist-businessman, Gregory Olsen, who is paying the Russian space agency $20 million for a weeklong visit.

posted by: kyawoo at 21:30 | link | comments |
space station

New findings on comets

The data gathered by Deep Impact spacecraft and telescopes indicates comet Tempel has layers that show in topographic relief, ranging from smooth surfaces to impact craters. It’s also extremely porous, which allows the surface to heat up and cool down almost instantly when hit by sunlight. It is found that the 72 trillion kilogram-nucleus was extremely porous, with as much as 80% of its volume taken up by empty space.

Observers estimate the impact released about 5 million kilograms of water from beneath the comet’s surface and between two and five times as much dust. There was so much dust, in fact, that mission members have not been able to see the impact crater with the high-resolution camera on the mission’s flyby spacecraft, about 500 km away.

Scientists estimate the impact blasted away a crater about 100 metres wide and up to 30 m deep. Crucially, organic molecules were among the material ejected. Neither the full range of molecules nor their abundances have been determined yet, but researchers say they have found a surprisingly high amount of methyl cyanide, a molecule seen in large quantities in another comet.

This supports theories that comets may have brought water and the building blocks of life to Earth.

posted by: kyawoo at 10:50 | link | comments |
comets

Active volcanoes on Mars

Fields of volcanic cones seen at the North Pole of Mars in images from Europe’s Mars Express probe suggest the Red Planet could still be geologically active. This suggests the volcanoes erupted very recently and that the site could have ongoing volcanism.

There may be 50-100 of the volcanic cones covering a flank of the North Pole about one million square kilometres in area. They are between 300m (984ft) and 600m (656 yard) tall.

In addition to the North Pole, other regions with recent - and possibly ongoing - activity on Mars include parts of Tharsis - home to the volcano Olympus Mons - parts of Elysium and the so-called highland-lowland boundary.

By counting the number of craters on the surfaces of Solar System objects, scientists can estimate the age of those surfaces. If they are heavily cratered, they are deemed older, while smoother surfaces are considered younger. This assumes a constant cratering rate since the heavy bombardment that terrestrial planets underwent about four billion years ago.

posted by: kyawoo at 21:16 | link | comments |
mars

Saturn’s rings have changed

Saturn’s rings have dramatically changed over just the past 25 years, scientists says.

Among the most surprising findings is that parts of Saturn’s innermost ring — the D ring — have grown dimmer since the Voyager spacecraft flew by the planet in 1981, and a piece of the D ring has moved 125 miles inward toward Saturn.

Scientists are interested in Saturn’s rings because they are a model of the disk of gas and dust that initially surrounded the sun. Studying them could yield important clues about how the planets formed from that disc 4.5 billion years ago.

posted by: kyawoo at 20:06 | link | comments |
saturn

New findings on Saturn ring particles

The particles that make up Saturn’s rings are more like "fluffy" snowballs than hard ice cubes, as some scientists had previously described them. And these grains have been found to be spinning more slowly than thought.

posted by: kyawoo at 20:25 | link | comments |
saturn

Hubble scaled down

NASA shut down one of the Hubble Space Telescope’s pointing gyroscopes this week in an effort to keep the observatory alive for an extra eight months or so.

Hubble was originally designed to use three of its six gyroscopes to point and stabilise itself in space. But the gyros regularly fail, and astronauts have already replaced them twice. Currently, two are broken.

The 15-year-old observatory is using just three gyros, with another in "standby" mode in case of another failure. The current configuration of gyros is expected to keep the telescope going until about 2007.

posted by: kyawoo at 21:35 | link | comments |
astronomy, unmanned missions