Science and Space

space and astronomy articles.

Who Links Here

Decline of Arctic sea ice increases

For the fourth consecutive year, scientists using satellite data have tracked a stunning reduction in arctic sea ice at the end of the northern summer. If current rates of decline in sea ice continue, the summertime Arctic could be completely ice-free well before the end of this century.

Arctic sea ice extent, or the area of ocean that is covered by at least 15 percent ice, typically reaches its minimum in September, at the end of the summer melt season. On September 21, 2005, the five-day running mean sea ice extent dropped to 5.32 million square kilometers (2.05 million square miles), the lowest extent ever observed during the satellite record

This decline in sea ice amounts to approximately 1.3 million square kilometers (500,000 square miles). This is an area roughly equivalent to twice the size of Texas.

Having four years in a row with such low ice extents has never been seen before in the satellite record. It clearly indicates a downward trend, not just a short-term anomaly.

Since 2002, satellite records have also revealed that springtime melting is beginning unusually early in the areas north of Alaska and Siberia. The 2005 melt season arrived even earlier, beating the mean melt onset date by approximately 17 days, this time throughout the Arctic

In addition, arctic temperatures have increased in recent decades. Compared to the past 50 years, average surface air temperatures from January through August, 2005, were 2 to 3 degrees Celsius (3.6 to 5.4 degrees Fahrenheit) warmer than average across most of the Arctic Ocean

posted by: kyawoo at 21:19 | link | comments |
earth

Venus Express

Venus Express, European Space Agency’s spacecraft to Venus is scheduled to lift off aboard a Soyuz rocket from Baikonur, Kazakhstan, on 26 October. When it arrives at Venus in April 2006, it will study the planet from a polar orbit stretching from an altitude of 250 to 60,000 kilometres.

The mission will focus mainly on the composition and temperature of Venus’s atmosphere. It rotates 50 to 60 times faster than the planet itself, which spins just once every 243 days and in the opposite direction to Earth. In particular, researchers will study mysterious hurricane-like vortices above the poles.

Astronomers hope to understand how a planet that has more in common with Earth than any other in terms of distance from the Sun, size and mass could have evolved into such an inhospitable world. Temperatures hover at 450°C, while the thick, carbon dioxide atmosphere produces crushing surface pressures 90 times those on Earth and sulphuric acid rains from the sky. Scientists are still struggling to understand why Venus is so radically different from Earth.

The surface will also be scanned for active volcanism, hinted at by the presence of sulphuric acid in the atmosphere, but never seen. Venus boasts the most volcanoes of any planet in the solar system. Nearly 90% of its surface is covered by basaltic lava flows. Based on the size and number of impact craters, the lava appears to be about 500 million years old.

This age suggests that, unlike Earth, Venus does not have multiple rocky plates that constantly move and collide over the hot, soft rock in the planet’s core. On Earth, plate tectonics enables heat to escape from the core.

Local volcanic activity probably goes on all the time and the gases belched out in the process would "go a long way toward explaining Venus’s extreme climate".

The mission is the first dedicated to Venus since NASA’s Magellan spacecraft mapped the surface of the planet in 1990. Venus Express is scheduled to operate for about 500 Earth days - the equivalent of two rotations of Venus - but it has enough fuel to last 1000 days.

posted by: kyawoo at 19:07 | link | comments |
venus

Are Shuttle and ISS colossal mistakes?

Yes, both the Space Shuttle and the International Space Station were colossal mistakes, according to NASA director Michael Griffin.

It is estimated that NASA has spent about $150 billion on the shuttle program since its inception in 1971. The total cost of the space station by the time it’s finished — in 2010 or later — may exceed $100 billion, though other nations will bear some of that.

Griffin told the Senate earlier this year that the shuttle was "deeply flawed" and that the space station was not worth "the expense, the risk and the difficulty" of flying humans to space.

Joe Rothenberg, head of NASA’s manned space programs from 1995 to 2001, defended the programs for providing lessons about how to operate in space. But he conceded that "in hindsight, there may have been other ways."

posted by: kyawoo at 20:53 | link | comments |
space station, space shuttle

China’s second manned space mission on Oct. 13

China announced plans to launch its second manned space mission on Oct. 13. The flight will involve two astronauts and return five days later.

The launch of Shenzhou VI is scheduled for 11 a.m. at Jiuquan Satellite Launch Base, in the Gobi desert in northern China. Shenzhou VI is not just a duplicate of "Shenzhou V" at all. Over 100 technological modifications have been made in "Shenzhou VI". The prolonged flight of "Shenzhou VI" will also be conducive to scientific research. "Shenzhou VI" will carry more subjects of experiment up the space. During the long flight, the two astronauts will be able to take off their 10 kg space suits, open the door between the return cabin and the orbit cabin, and enter for the first time the orbit cabin to conduct scientific experiments. In the cabin of "Shenzhou VI", sleeping bags are provided in order to make the astronauts more comfortable; and the two astronauts can also warm up their food, do some sanitary work, and take a rest in turn.

The flight will involve two astronauts Shenzhou VI is not just a duplicate of "Shenzhou V" at all. Over 100 technological modifications have been made in "Shenzhou VI". The prolonged flight of "Shenzhou VI" will also be conducive to scientific research. "Shenzhou VI" will carry more subjects of experiment up the space. During the long flight, the two astronauts will be able to take off their 10 kg space suits, open the door between the return cabin and the orbit cabin, and enter for the first time the orbit cabin to conduct scientific experiments. In the cabin of "Shenzhou VI", sleeping bags are provided in order to make the astronauts more comfortable; and the two astronauts can also warm up their food, do some sanitary work, and take a rest in turn.

Three groups with a total of six astronauts are available to be finally chosen for "Shenzhou VI" in the countdown period. Zhai Zhigang, who was once Yang Liwei’s close comrade-in-arms, and Nie Haisheng are one of the three final groups. As viewed from various data and analyses, the "Zhai-Nie" group should be the strongest group with the greatest confidence. It is quite probable that this group will embark on "Shenzhou VI". However, this still depends on what happens in the last minute.

posted by: kyawoo at 10:58 | link | comments |
manned missions

How Earth was created

There are three major theories on how Earth may have been created. They are:
EVOLUTION: That human beings were descended from apes. Animals survived on the basis of natural selection, and changes "evolved" in animals over the years.
CREATIONISM: That God created the universe and the creatures who live in it.
INTELLIGENT DESIGN: That the universe didn't appear by accident. There was some "designer" who created the universe, but it isn't necessarily God. In fact, it is unknown who or what the "designer" of the universe was.

Which one do you accept?

posted by: kyawoo at 19:53 | link | comments (1) |
earth

How to define a planet.

Astronomers are arguing over how to define a planet.

The International Astronomical Union (IAU), which is responsible for settling such issues, assembled a special working group to come up with a new definition about 18 months ago.

Then a large object was discovered in July 2005 in a ring of rocky bodies beyond Neptune called the Kuiper Belt. It was dubbed the "tenth planet" by its discoverers because it is larger than Pluto. But the 19-member working group has been unable to arrive at a consensus.

Some submitted a proposals based simply on an object’s size.

The second proposal says a planet is the dominant body in its immediate neighbourhood - a title based on its size relative to its neighbours and the dynamics of its orbit. Objects in the asteroid belt beyond Mars, for example, would not be planets because there are so many of them in the same region, while Pluto would not count because it crosses the orbit of its more massive neighbour Neptune.

But a third proposal has been discussed that does away entirely with the term "planet". It uses qualifying adjectives to define subclasses of planets based on characteristics like location, composition or culture. In this scheme, Earth might be a "terrestrial planet" and Pluto a "historic planet".

The working group may vote on the proposals within the next two weeks.

posted by: kyawoo at 11:11 | link | comments |
planets

Global warming on Mars

Global Surveyor spacecraft orbiting Mars reveals subtle signs of possible slow warming trend.

The observations showed an annual 10-foot erosion in the snow cap at the South Pole. The cap is made of frozen carbon dioxide, the chief ingredient of the Martian atmosphere.

The scientists said the causes and time frame of the Martian climate change are not clear.

posted by: kyawoo at 11:33 | link | comments |
mars

Satellite built by students will be launched soon

A microsatellite built largely from donated parts in university workshops across Europe is just over one week from launch. It took only 18 months for more than 400 students – spread across 23 universities and 12 countries – to design and build the SSETI Express spacecraft. Set to launch from Russia’s Plesetsk Cosmodrome on Sept. 30, the project is part an education effort by the European Space Agency (ESA) to boost student interest in space technology and offer some hands-on experience.

SSETI Express, short for Student Space Exploration Techology Initiative Express, is a boxy satellite about the size of a small washing machine. The 136-pound (62-kilogram) spacecraft is expected to snap photographs of Earth, test a cold-gas attitude control system and function as a radio transponder for amateur radio operators.

The spacecraft will also serve as a mothership for three picosatellites, tiny cubes just under four inches (10 centimeters) wide, built by universities in Germany, Japan and Norway. The picosatellites will be ejected into space on orbit.

The spacecraft cost less than $121,185 (100,000 euros) to piece together, thanks to donated material, equipment and expertise from participating universities and industry businesses, ESA officials said.

SSETI Express is the first of three microsatellites built by student teams.

posted by: kyawoo at 20:11 | link | comments |
space science

Mars surface more active than thought

The surface of Mars is more active than previously thought. New photographs from Mars Global Surveyor show new impact craters and gullies. Scientists also say that deposits of frozen carbon dioxide near the planet’s south pole have shrunk for three summers in a row suggesting climate change is in progress.

The newly released images also show boulder tracks at another site, which were not there two years ago. It was the first evidence scientists had seen of some kind of seismic activity on the planet.

The Mars Global Surveyor has been orbiting the planet since 1997; Nasa expects it to carry on doing so for another five to 10 years.

posted by: kyawoo at 00:57 | link | comments |
mars

Sea on Titan

New radar images from the Cassini spacecraft revealed what appears to be a very distinct shoreline, fed by meandering channels carved deeply in the surrounding terrain.

And several long sinuous channels can be seen cutting through the bright region and ending at the shoreline, suggesting the existence of an Earth-like cycle of evaporation, rainfall and river systems to carry the liquid back to the sea. But instead of water, the liquid in this case is believed to be methane, kept liquid at Titan’s -179°C. surface temperature.

Seas of liquid methane, perhaps mixed with other hydrocarbons, had long been expected on Titan, the second-largest moon in the solar system. It is also the only moon with a thick atmosphere - thicker than Earth’s.

Titan’s abundance of hydrocarbons, thick atmosphere, and now evidence for the presence of large volumes of liquid, means it is considered a close analogue of the early Earth.

Cassini’s next close flyby of Titan will take place on 26 October and will focus on the region where the landing probe Huygens hurtled down to Titan’s surface in December 2005.

posted by: kyawoo at 00:10 | link | comments |
saturn