These stunning images capture the final stage of the construction of the International Space Station.

But as they marked the beginning of a new era in space exploration, the spacewalk undertaken by Gregory Chamitoff and Mike Fincke also represented an end - of Nasa's 30-year shuttle programme.

All future spacewalks - including one during the final shuttle voyage this summer - will be performed by full-time space station residents.

'This space station is the pinnacle of human achievement and international co-operation,' spacewalker Gregory Chamitoff observed before heading back inside.

'Twelve years of building and 15 countries and now it's the Parthenon in the sky and hopefully the doorstep to our future. So congratulations everybody on assembly complete.'

The two astronauts completed construction of the International Space Station with the smooth addition of an extension boom.

Mr Chamitoff said it was fitting for Endeavour to be present for the last spacewalk by a shuttle crew - conducted on the next-to-last flight of the shuttle era - since it was present for the first in December 1998. It was the fourth spacewalk in a week for the Endeavour astronauts, who will head back to Earth in just a few days.

Mr Chamitoff and his spacewalking partner, Mike Fincke, teamed up with robot arm operator Gregory Johnson to accomplish the last construction job.

'Assembly complete. Amazing,' Mr Chamitoff said once the 50ft boom was latched securely in place. 'Boy, this is a big space station,' he marvelled several minutes later.

The Endeavour astronauts wished the future spacewalkers well as the hatch to the outside was shut.

Another milestone was achieved, 1,000 hours of spacewalking at the orbiting outpost.

Astronauts had previously logged 995 hours outside for space station assembly and maintenance. Mr Fincke and Mr Chamitoff hit the 1,000-hour mark five hours into their seven-hour spacewalk, the 159th to build the station and keep it humming.

The space station's newly attached boom was used by shuttle Endeavour's astronauts on Thursday to survey their ship for micro-meteorite damage. Nasa is reviewing the 3D images and if everything looks good, managers will clear Endeavour for next week's trip home. Read More

For years, the greatest minds in astrophysics have grappled with the 'missing mass' question.

They knew that universe contained more mass than was visible in planets, stars and other objects - but they didn't know where to find it.

But an Australian undergraduate has been able to crack the scientific conundrum in a matter of weeks this summer.

Amelia Fraser-McKelvie, 22, discovered the missing material after spending a holiday internship with a team of researchers at Monash University's School of Physics.

The aerospace engineering student conducted a targeted X-ray search of vast structures known as 'filaments of galaxies', which stretch across the vast expanse of space.

Examining data that the research team had already gathered, her analysis of the material confirmed that mass was present in the filaments.

Monash astrophysicist Dr Kevin Pimbblet explained that scientists had previously detected matter that had been present in the early history of the universe but that could not now be located.

He added that astrophysicists had known about the missing mass for the past two decades, but the technology needed to pinpoint its location had only become available in recent years.

'We don't know where it went. Now we do know where it went because that's what Amelia found,' he said.

He said the discovery could drive the construction of new telescopes designed to specifically study the mass. Read More

Astronomers have created a 'galactic train wreck' atlas image depicting how a variety of galaxies around Earth will collide in five billion years time.

The collision between the Milky Way - Earth's galaxy - and the Andromeda Galaxy is predicted to take place in between three and five billion years.

The 'train wreck' style merger of galaxies, is said by experts to reveal 'how galaxies form, grow and evolve'.

The atlas of galaxy collision was created using data from NASA's Spitzer and Galex space telescopes.

The Galex (Galaxy Evolution Explorer) telescope observes in ultraviolet light, which captures emission from hot young stars.

Spitzer sees the infrared emission from warm dust heated by those stars, as well as from stellar surfaces.

Some galaxies, such as the NGC 935 and the IC 1801, have already begun their galactic 'smash-up'.

But the collision between Earth's Milky Way and the Andromeda Galaxy is not expected to take place for several billion years.

The collision is likely to trigger the birth of stars from smashed together clouds of cosmic gas and dust.

Lauranne Lanz of the Harvard Smithsonian Center for Astrophysics, said: 'This atlas is the first step in reading the story of how galaxies form, grow, and evolve. Read More

Water may be as plentiful in the moon's interior as the Earth's, a study of Apollo mission lunar rocks has revealed.

Trapped water was found in tiny volcanic glass beads returned to Earth in 1972 by the final manned mission to the moon, Apollo 17.

Analysis of the samples suggests there could be 100 times more water in the lunar mantle, the thick rock layer beneath the surface crust, than was previously thought.

In fact, there could be as much water in the lunar mantle as in the Earth's mantle.

If this is the case, it challenges a long-held theory about the moon's formation.

Most experts believe a huge impact early in Earth's history ejected material into space that became the moon.

But the force involved should have vaporised much of the future moon's water. Finding large amounts of water in the moon's interior casts doubt on this idea.

Professor James van Orman, from Case Western Reserve University in the US, who led the research reported today in the journal Science, said: 'These samples provide the best window we have to the amount of water in the interior of the moon. The interior seems to be pretty similar to the interior of the Earth, from what we know about water abundance.' Read More

Nasa has unveiled a design for a spaceship that could propel four astronauts on a six-month voyage to Mars.

Engineers are already assembling of the Multi-Purpose Crew Vehicle or MPCV, which is based on the Orion crew capsule developed to return men and women to the moon.

They hope to have the shuttle ready to orbit the Earth within five years and eventually make the 47million-mile trip to Mars.

The Constellation Project that was building Orion had initially been scrapped by President Barack Obama. But he relaunched it in April last year after changing the object of the mission.

Instead of going back to the moon, Mr Obama announced that Nasa would aim to reach an asteroid by 2020 and after that send astronauts to Mars. Read More

$1BN MISSION FOR 5LB SPACE DUST

A Nasa spacecraft will reach out and touch an asteroid and send pieces back to Earth, it was revealed today.

The unmanned probe won't land on the rocky body.

But it will get close enough to kiss the surface and extend a robotic arm to grab up to 5lb of dust and organic material, shown below in an artist's impression.

The samples will be sealed in a capsule for the trip home.

Asteroids are considered leftovers from the formation of the solar system some 4.5billion years ago.

Studying them could shed light on the conditions of the infant solar system and how life emerged. These giant speeding rocks fly by Earth harmlessly most of the time, but have occasionally smacked the planet with disastrous results.

A five-year survey of 200,000 galaxies, stretching back seven billion years in cosmic time, has led to one of the best independent confirmations that dark energy is driving our universe apart at accelerating speeds.

The survey used data from NASA's space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.

The findings offer new support for the favored theory of how dark energy works -- as a constant force, uniformly affecting the universe and propelling its runaway expansion. They contradict an alternate theory, where gravity, not dark energy, is the force pushing space apart. According to this alternate theory, with which the new survey results are not consistent, Albert Einstein's concept of gravity is wrong, and gravity becomes repulsive instead of attractive when acting at great distances.

"The action of dark energy is as if you threw a ball up in the air, and it kept speeding upward into the sky faster and faster," said Chris Blake of the Swinburne University of Technology in Melbourne, Australia. Blake is lead author of two papers describing the results that appeared in recent issues of the Monthly Notices of the Royal Astronomical Society. "The results tell us that dark energy is a cosmological constant, as Einstein proposed. If gravity were the culprit, then we wouldn't be seeing these constant effects of dark energy throughout time." (read more)

It sounds like something out of science fiction - a huge swathe of the moon covered with solar panels to beam captured energy back to Earth.

But plans to turn the moon into a gigantic mirrorball manned by robots to provide all the Earth's energy came a step closer to reality today when they were unveiled by Japanese scientists.

The ambitious project would result in 13,000 terawatts of continuous solar energy being transmitted back to receiving stations on Earth, either by laser or microwave.

The plans were unveiled by Japanese construction giant Shimizu Corporation's research division, and would result in a 6,800 mile-long band stretching around the light side of the moon's equator.

It would measure up to 248 miles in width and feature 12 mile-wide antennae to transmit the power.

The quest for finding alternate energy sources has been hastened in Japan in the wake of the Fukushima nuclear power station crisis sparked by the tsunami in March.

No intended timeline for the project - which would result in the biggest public infrastructure installation ever constructed - has been announced. Read More

Astronomers may have detected the most distant and ancient object ever seen, a massive explosion that lit up the early universe soon after its birth.

When the blast, known as a gamma ray burst (GRB), occurred, the universe was less than four per cent of its present age and 10 per cent of its current size.

Light from the event has taken 13.14billion light years to reach the Earth. It began its journey only about 600million years after the Big Bang that created the cosmos.

The source of the burst, designated GRB 090429B, was an exploding star which for a brief time shone a million million times more brightly than the Sun.

Its fading ‘afterglow’ was detected by the American space agency's Swift satellite in April 2009.

Two years of analysis has now shown the object to be a candidate record breaker.

British astronomer Dr Andrew Levan, from the University of Warwick, who was one of the first to view the explosion, said: ‘The race to find distant objects stems from the desire to find and study the first stars and galaxies that formed in the Universe, in the first few hundred million years after the Big Bang. Read More

The most complete 3D map of the local universe has been unveiled by British astronomers.

The 2MASS Redshift Survey (2MRS) from the University of Portsmouth extends to a distance of 380 million light years and has taken 10 years to complete.

It extends closer than previous surveys to the galactic plane - a region that is generally obscured by dust.

The survey has mapped in detail areas previously hidden behind the Milky Way to better understand the impact they have on its motion in relation to the rest of the universe.

Karen Masters from the University of Portsmouth presented the map in a press conference at the 218th meeting of the American Astronomical Society in the Harvard-Smithsonian Centre for Astrophysics (CfA) in Cambridge, Massachusetts.

She said: 'The 2MASS Redshift Survey is a wonderfully complete new look at the local universe - particularly near the galactic plane.

'A galaxy's light is 'redshifted' or stretched to longer wavelengths by the expansion of the universe. The farther the galaxy, the greater its redshift, so redshift measurements yield galaxy distances.

'It's the vital third dimension in a 3D map and will enable cosmologists to study the area in much more detail.'

Earlier this month, scientists had revealed a similarly massive scale 3D map of the universe, which was one of the most complex images of the cosmos ever made.

Scientists behind the SDSS III map studied the brightest objects in the sky and came up with an image akin to 'looking at the moon through the clouds'. Source

Astonishingly beautiful, this is the most detailed image of particle jets erupting from a super-massive black hole yet captured.

It shows a region in the nearby galaxy of Centaurus A that is just under 4.2 light-years across - less than the distance between our sun and the nearest star.

Radio-emitting features as small as 15 light-days can be seen, making this the highest-resolution view of galactic jets ever made.

Lead researcher Cornelia Mueller, from the University of Erlangen-Nuremberg in Germany, said: 'These jets arise as in-falling matter approaches the black hole, but we don't yet know the details of how they form and maintain themselves.'

The image was taken using radio telescopes located throughout the southern hemisphere.

Centaurus A contains a super-massive black hole weighing 55million times the sun's mass.

Also known as NGC 5128, it is located about 12million light-years away in the constellation Centaurus and is one of the first celestial radio sources identified with a galaxy.

Seen in radio waves, Centaurus A is one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. Read More

From a safe distance, the blue-tinted mass on the horizon of Jupiter's volcanic moon has a mesmerising beauty.

However these destructive eruptions put the 12-mile-high mushroom cloud currently emitting from Iceland's Grimsvotn volcano firmly in the shade.

These incredible images of two sulfurous eruptions on Jupiter's Io show plumes rising 86 and 46 miles above the moon.

The pictures were captured by a camera on board the robotic Galileo spacecraft, which orbited Jupiter between 1995 an 2003.

In one of the images, on Io's horizon, a blue-ish plume rises on Io's horizon, pushing rock and sulfurous gases about 86 miles - or 140 kilometres - above the surface of the volcanic caldera known as Pillan Patera.

The same image, in the middle near the the shadow line, the ring-shaped Prometheus plume is seen rising about 46 miles - or 75 kilometres - above Io while casting a shadow below the volcanic vent. Read More