RSSArchive for June, 2010

Cosmic watercolour

R Corona Australis nebula

The R Corona Australis nebula is a complex mix of gas and dust 420 light-years from Earth, where young stars are beginning their lives.

  • R Corona Australis starbirth region
  • 420 light-years from Earth
  • Gas glows blue from reflected starlight

This magnificent view of the region around the star R Coronae Australis was created from images taken with the Wide Field Imager (WFI) at the European Southern Observatory’s (ESO) La Silla Observatory in Chile.

R Coronae Australis lies at the heart of a nearby star-forming region and is surrounded by a delicate bluish “reflection” nebula embedded in a huge dust cloud.

The new image—a combination of twelve separate pictures taken through red, green and blue filters—reveals surprising new details in this dramatic area of sky, which spans roughly the width of the full Moon.

The nebula is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). The complex is named after the star R Coronae Australis, which lies at the centre of the image. It is one of several stars in this region that belong to the class of very young stars that vary in brightness and are still surrounded by the clouds of gas and dust from which they formed.

See the full-size version of the image here (new window).

Colours of the night

The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength.

These complex processes, determined by the physics of interstellar gas and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles.

The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic pink colour seen in many star-forming regions.

The image below shows a wider view of the R Corona Australis region. See the full-size version here (new window).

R Corona Australis nebula

A wider view of the R Corona Australis region. A globular star cluster, NGC 6723, is just above and to the right.

A prominent dark “lane” crosses the image from the centre to the bottom left. Here the visible light emitted by the stars that are forming inside the cloud is completely absorbed by the dust. These stars could only be detected by observing at longer wavelengths, by using a camera that can detect infrared radiation.

Adapted from information issued by ESO.

Amazing NASA video

  • Space Station has made 66,500 orbits since 1998
  • Astronauts see 15-16 sunrises/sunsets each day
  • Each orbit takes only 92 minutes

The International Space Station orbits 354 kilometres (220 miles) above the Earth, completing one trip around the globe every 92 minutes. Cruising along at 27,700 km (17,200 miles) per hour, the astronauts experience 15 or 16 sunrises and -sets every day.

Since the launch of the Zarya Control Module on November 20, 1998, the station has orbited the Earth over 66,500 times (as of June 27, 2010). The station’s orbit is inclined to the equator by 51.65°, meaning at its most northerly, it is at the latitude of London, England, and at it most southerly it is over the latitude of the Falkland Islands.

The video above is sequence of time-lapse photographs illustrating roughly half an orbit, from sunrise over Northern Europe (photo below) to sunset southeast of Australia, on April 28, 2010. The view looks to the north of the station’s ground track. In the upper-left, is the tail of the Space Shuttle Discovery, which docked with the Space Station during the STS-131 mission.

Sunrise over Northern Europe

Sunrise over Northern Europe, seen from the International Space Station.

The animation begins with a view of snow-covered Norway (image top) and the Jutland Peninsula (image centre). Low clouds cover Central Europe (image bottom).

The animation continues as the Station flies by Ukraine, eastern Russia, the Volga River, and then the Russian Steppes. South and east of the steppes, a dust storm comes into view over the Taklimakan Desert, followed shortly by the lake-studded Tibetan Plateau and the glaciers of the Himalayan Mountains (photo below). Smoke-shrouded lowlands hug the southern margin of the Himalaya. Smoke also covers much of Southeast Asia, including the Irrawaddy Delta.

The Tibetan Plateau and the glaciers of the Himalayan Mountains

The Tibetan Plateau and the glaciers of the Himalayan Mountains

After the Space Station passes over the sapphire-blue South China Sea, the island of Borneo appears, followed by the open expanse of the Indian Ocean. A trio of coral reefs lies off the coast of Western Australia, which is studded with clouds. Australia’s arid interior is coloured myriad shades of red (photo below).

Australia seen from orbit

The arid interior of Australia seen from orbit.

As sunset nears, cloud shadows lengthen, highlighting their structure. Night falls as the Space Station crosses the terminator (the “line” dividing the day and night halves of Earth) above the South Pacific.

Astronaut photographs STS131-E-11693 to STS131-E-12195 courtesy NASA JSC Image Science & Analysis Laboratory. Animation by Robert Simmon Text adapted from text written by Robert Simmon. Special thanks to William L. Stefanov, NASA-JSC.

Super-organics found in space

Diagram showing part of the Perseus star formation region, the William Herschel Telescope and a model of anthracene

The molecule anthracene has recently been identified in the Perseus star formation region. It is composed of three hexagonal rings of carbon atoms surrounded by hydrogen atoms.

  • Anthracene found in deep space
  • A “prebiotic” molecule that leads to amino acids
  • Chemical of life on Earth, could be common in space

A team of scientists from the Instituto Astrofisica de Canarias (IAC) and the University of Texas has succeeded in identifying one of the most complex organic molecules yet found in the material between the stars, the so-called interstellar medium.

The discovery of anthracene could help resolve a decades-old astrophysical mystery concerning the production of organic molecules in space.

‘We have detected the presence of anthracene molecules in a dense cloud in the direction of the star Cernis 52 in Perseus, about 700 light-years from the Sun,’ explains Susana Iglesias Groth, the IAC researcher heading the study.

In her opinion, the next step is to investigate the presence of amino acids. Molecules like anthracene are “prebiotic”, so when they are subjected to ultraviolet radiation and combined with water and ammonia, they could produce amino acids and other compounds essential for the development of life

‘Two years ago,’ says Iglesias, ‘we found proof of the existence of another organic molecule, naphthalene, in the same place, so everything indicates that we have discovered a star formation region rich in prebiotic chemistry.’

Until now, anthracene had been detected only in meteorites and never in the interstellar medium.

Dome of the William Herschel Telescope

Dome of the William Herschel Telescope

Chemicals of life in space?

Oxidised forms of this molecule are common in living systems and are biochemically active. On our planet, oxidised anthracene is a basic component of aloe and has anti-inflammatory properties.

The new finding suggests that a good part of the key components in terrestrial prebiotic chemistry could be present in interstellar matter.

Since the 1980s, hundreds of “signatures” found in the spectrum of the interstellar medium, known as diffuse spectroscopic bands, have been known to be associated with interstellar matter, but their origin has not been identified until now.

The new discovery indicates that they could result from molecular forms based on anthracene or naphthalene.

Since they are widely distributed in interstellar space, they might have played a key role in the production of many of the organic molecules present at the time of the formation of the Solar System.

The results are based on observations carried out at the William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands and with the Hobby-Eberly Telescope in Texas in the United States.

The researchers report their findings in the journal Monthly Notices of the Royal Astronomical Society.

Adapted from information issued by the Royal Astronomical Society / Instituto Astrofisica de Canarias / Gaby Perez and Susana Iglesias-Groth / ING.

Caspian Sea from orbit

The Caspian Sea seen from orbit

The Caspian Sea covers 371,000 square kilometres and borders five countries.

Measured by surface area, the Caspian Sea is the world’s largest inland water body. It covers roughly 371,000 square kilometres (143,200 square miles) and borders five countries. To the ancient Greeks and Persians, the lake’s immense size suggested it was an ocean, hence its name.

A large expanse of clear sky permitted an unobstructed view of the Caspian Sea in early June 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-colour image on June 4, 2010.

The colour of the Caspian Sea darkens from north to south, thanks to changes lake in depth and perhaps sediment and other runoff. The northern part of the lake is just 5 to 6 metres (16 to 20 feet) deep. The southern end, however, plunges more than 1,000 metres (3,300 feet).

See the full-size image here (3MB, new window)

Just as the lake reaches a greater depth in the south, the nearby land reaches a greater height. The mountains of northern Iran line the southern end of the giant lake, and emerald green vegetation clings to those mountain slopes.

In marked contrast to the mountains, sand seas line the southeastern and northern perimeters of the lake, and marshes occur along the lake shores in Azerbaijan to the west.

Multiple rivers empty into the Caspian Sea, the Volga being the largest. Lacking an outlet, the Caspian Sea loses water only by evaporation, leading to the accumulation of salt.

Although a lake, the Caspian is not a freshwater lake; the water delivered by the Volga River minimises the lake’s salt content at the northern end, but the Caspian grows more saline to the south. Kara-Bogaz-Gol is a saline inlet along the lake’s eastern perimeter.

Geological research indicates that the Caspian Sea was once part of a prehistoric sea known as the Paratethys. Tectonic forces uplifting the land and a drop in sea level left the Caspian landlocked more than 5 million years ago. Climate shifts have alternately raised and lowered the lake’s water levels, sometimes nearly drying it out completely.

NASA image by Jeff Schmaltz, MODIS Rapid Response Team. Text adapted from information issued by Michon Scott.

Rocket launch video

Arianespace stepped up its 2010 launch pace with the successful lift-off of a “dual-passenger” Ariane 5 rocket mission on Saturday, which lofted payloads for the Middle East and South Korea.

Launching from the ELA-3 launch facility in French Guiana, the Ariane 5 ECA placed Arabsat-5A and COMS into geostationary transfer orbits—providing a payload delivery performance of approximately 7,400 kg.

“This launch is the 37th consecutive success for our Ariane 5 launcher, and it clearly demonstrates our policy of quality—which is exactly what you—our customers expect, and I thank you for the confidence you have always shown for us,” Arianespace Chairman & CEO Jean-Yves Le Gall said in comments from the Spaceport’s Jupiter mission control room.

During Saturday’s launch, the Arabsat-5A satellite was deployed first during the flight sequence, being released from atop Ariane 5’s payload “stack” at 26 minutes into the mission.  Produced by Astrium and Thales Alenia Space for the Arabsat telecommunications operator, the satellite had a mass at lift-off of about 4,940 kg.

Launch of the Ariane 5 V195 mission

Launch of the Ariane 5 V195 mission

Arabsat-5A carries transponders for telecommunications and TV broadcasting services over the Middle East and Africa.  Astrium provided the Eurostar 3000 spacecraft platform and was responsible for satellite integration, while Thales Alenia Space supplied the payload.

The COMS satellite was separated from Ariane 5 at 32 minutes into the flight.  The multi-purpose COMS spacecraft for South Korea’s KARI (Korea Aerospace Research Institute) is fitted with three payloads for meteorological observation, ocean surveillance and experimental broadband multimedia communications services.

Following the launch, Le Gall announced that the next Ariane 5 mission will be another dual-passenger flight, which is scheduled for August 3 with RASCOM-QAF 1R and NILESAT 201.

“Since the creation of our company 30 years ago, we have successfully launched 281 satellites,” Le Gall said. “And this will continue, as our order book today has 34 satellites for launch to geostationary orbit, along with six Ariane 5 missions with the Automated Transfer Vehicle, and 17 launches to be performed by Soyuz. And since the beginning of 2010, we already have signed nine new contracts—the latest of which is with the Argentinean operator Arsat, which I am announcing today as a new contract.”

Adapted from information issued by Arianespace.

Supercomputer to boost Australian astronomy

A simulation of dark matter distribution

A simulation of the spread of dark matter in the universe, produced using a current-generation Swinburne University supercomputer. The new supercomputer will be up to 100 times better.

A multi-million dollar upgrade to Swinburne University’s supercomputer will make it a leading research facility for the Australian astronomy community.

The upgrade, which will receive $1 million from the Federal Government’s Education Investment Fund (EIF) and $2 million from Swinburne, will dramatically increase the speed and capacity of the facility—now known as ‘gSTAR’.

The EIF funding will finance the installation of Graphics Processing Units (GPUs), or ‘extra brains’ for the supercomputer. Originally developed by the computer gaming industry, GPUs are a type of processor designed to perform simple tasks in a massively-parallel way that leads to enormous increases in computational power.

The Swinburne contribution will be used to upgrade the existing Central Processing Units (CPUs) and the mass storage system and pay for a new machine room to host the facility.

According to Swinburne astrophysicist Dr Darren Croton, the installation of the GPUs will boost the supercomputer’s speed between two and 100 times, depending on the application.

“This means an astrophysics simulation that would previously have taken three months to complete might only take a single day.

“This huge advance in power gives us the opportunity to tackle problems that are potentially 100 times harder,” he said.

A rack of computer equipment

The new supercomputer will used technology adapted from games computers.

Specially designed for astronomy

While there are other supercomputer facilities in Australia that are also starting to use GPU technology, they cater to a wide range of researchers and interests.

“Because these are general purpose facilities, they have to be set up in a very general way,” Croton said.

“The gSTAR’s power lies in its unique application. It will be optimised for astronomy simulations and data processing, which means it will have the same amount of power as other facilities for about one percent of the cost. That’s bang for your buck.”

Croton said that the university will make the gSTAR a national facility for astronomers across the country.

“We’re making the gSTAR and its predecessor available to astronomers from other universities and research centres.”

“In exchange the National Computational Infrastructure (NCI) National Facility is funding a support person who will provide expertise and guidance to researchers, helping them optimise their code.”

The upgrade, which will see the raw power of the Swinburne supercomputer go from 10 teraflops to 600 teraflops, is expected to be completed early- to mid-next year.

Adapted from information issued by Swinburne University / Image by Dr Gregory Poole, Centre for Astrophysics and Supercomputing, Swinburne University of Technology.

Pulsars aren’t perfect

Artist's impression of a pulsar

An artist's impression of a pulsar. Blue lines represent its surrounding magnetic fields, while the purple beams represent the radio waves it emits.

  • Pulsars are small, spinning, magnetised stars
  • Emit regular pulses of radio waves
  • Act like celestial clocks

CSIRO astronomer George Hobbs and colleagues in the UK, Germany and Canada report in the journal Science that they’ve taken a big step towards solving a 30-year-old puzzle—why the “cosmic clocks” called pulsars aren’t perfect.

Pulsars are small, spinning stars that emit a beam of radio waves. When the beam sweeps over the Earth we detect a highly-regular “pulse” of radio waves. The rate at which the pulses repeat, fast or slow, depends on how fast the pulsar spins and therefore how often its radio beam flashes across the Earth.

The work is based on observations of 366 pulsars collected over several decades with the 76m radio telescope at the Jodrell Bank Observatory, run by the University of Manchester, and grew out of work George Hobbs did for his PhD thesis.

Each pulsar generates a cocoon of magnetic fields around itself—its magnetosphere.

The astronomers found that a pulsar’s magnetosphere switches back and forth between two different states.

“We don’t know exactly what happens,” Dr Hobbs said.

“But one idea is that from time to time there is a surge of charged particles—electrons, for instance—whirling through the magnetosphere. Such a surge could apply the brakes a bit to the pulsar spin, and also affect the pulsar’s radio beam.”

The change in a pulsar’s magnetosphere shows up both in the shape of the radio pulses recorded on Earth and the regular pattern of the pulses’ arrival times.

“Pulsars are very stable timekeepers, but not perfect,” said Dr Andrew Lyne of the University of Manchester, lead author of the Science paper and George Hobbs’ PhD supervisor.

“They have what we call ‘pulsar timing noise’, where the spin rate appears to wander around all over the place. This had baffled people for decades.”

Jodrell Bank 76m radio telescope

The Jodrell Bank 76m radio telescope

One of the aims of Dr Hobbs’ PhD thesis was to find an effective way to filter out this ‘timing noise’.

“We worked out how to do this, and along the way we were prompted to think hard about the nature of the timing noise,” Dr Hobbs said.

Haven’t solved all the mysteries yet

The key advance was noticing that when the pulsar timing changed, so did the shape of the radio pulse. “This ran against accepted thinking,” Dr Hobbs said. “Everyone had said they were unrelated. But we’ve shown they are.”

Now astronomers can compensate for ‘timing noise’ by using the pulse shape change to spot when the pulsar magnetosphere has changed its state—this will show when the pulsar spin rate has also changed.

“We now have a more fundamental understanding of how pulsars work,” Dr Hobbs said.

“We’ve shown that many pulsar characteristics are linked, because they have one underlying cause.”

Armed with this understanding, astronomers will find it easier to compensate for errors in their pulsar “clocks” when they use them as tools—for instance, in trying to detect gravitational waves, which is something Dr Hobbs is doing with CSIRO’s Parkes radio telescope.

But Dr Hobbs adds that there is no explanation yet as to why a pulsar’s magnetosphere flips from one state to another.

“The switching seems random in some pulsars and regular in others,” he said.

“We haven’t solved all the mysteries yet.”

Adapted from information issued by CSIRO / Russell Kightley / Jodrell Bank Centre for Astrophysics.

Volcano at the end of the world

Volcán Villarrica

Volcán Villarrica, an active volcano near the southern tip of South America.

Near the southern tip of South America, a trio of volcanoes lines up perpendicular to the Andes Mountains. The most active is the westernmost, Volcán Villarrica, pictured in this photo-like image from the Advanced Land Imager on NASA’s Earth Observing-1 (EO-1) satellite on May 15, 2010.

The 2,582-metre-high (9,357-foot) stratovolcano is mantled by a 30-square-kilometre (10-square-mile) glacier field, most of it amassed south and east of the summit in a basin made by a caldera depression. To the east and northeast, the glacier is covered by ash and other volcanic debris, giving it a rumpled, brown look.

The western slopes are streaked with innumerable grey-brown gullies, the paths of lava and mudflows (lahars). Beyond the reach of ash and debris deposits, the volcano is surrounded by forests; the area is a national park.

See the full-size image here (4MB, new window).

The biggest recent eruption was in the early 1970s; lava flows melted glaciers and generated lahars that spread at speeds of 30–40 kilometres per hour (20-30 mph) toward Lago Villarrica (visible to the northwest in large image) and southwest toward Lago Calafquéen (lower left).

NASA Earth Observatory image by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Text adapted from information issued by Rebecca Lindsey.

Comet probe pays visit to Earth

Artist's impression of Deep Impact and comet Tempel 1

Artist's impression of the then Deep Impact spacecraft visiting Comet Tempel 1 in 2005. Now renamed EPOXI, the spacecraft will visit another comet in November 2010.

  • EPOXI mission bound for Comet Hartley 2
  • To make fly-by of Earth to pick up speed
  • Due to reach the comet in November 2010

On Sunday, NASA’s historic Deep Impact spacecraft will fly past Earth for the fifth and last time on its current University of Maryland-led EPOXI mission. At time of closest approach to Earth, the spacecraft will be about 30,400 kilometres (18,900 miles) above the South Atlantic.

Mission navigators have tailored this trajectory to change the shape of the spacecraft’s orbit and to boost it on its way to the mission’s ultimate fly-by, a close encounter with comet Hartley 2 in November.

Diagram showing EPOXI's orbit and fly-bys

EPOXI will make a fly-by of Earth on June 26, and reach Comet Hartley 2 in November 2010.

“The speed and orbital track of the spacecraft can be changed by changing aspects of its fly-by of Earth, such as how close it comes to the planet,” explained University of Maryland astronomer Michael A’Hearn, principal investigator for both the EPOXI mission and its predecessor mission, Deep Impact.

“There is always some gravity boost at a fly-by and in some cases, like this one, it is the main reason for a fly-by,” said A’Hearn.

“The last Earth fly-by was used primarily to change the tilt of the spacecraft’s orbit to match that of comet Hartley 2, and we are using Sunday’s fly-by to also change the shape of the orbit to get us to the comet.”

The Deep Impact mission made history and headlines worldwide when it smashed a probe into comet Tempel 1 on July 4, 2005.

“Earth is a great place to pick up orbital velocity,” said Tim Larson, the EPOXI project manager from NASA’s Jet Propulsion Laboratory. “This fly-by will give our spacecraft a 1.5-kilometer-per-second [3,470 mph] boost, setting us up to get up close and personal with comet Hartley 2.”

A recycled mission

EPOXI is an extended mission of the Deep Impact fly-by spacecraft. Its name is derived from this mission’s two tasked science investigations—the Deep Impact Extended Investigation (DIXI) and the Extrasolar Planet Observation and Characterization (EPOCh).

Impact on Comet Tempel 1

In 2005, an impactor was collided with Comet Tempel 1, resulting in this huge flash.

On November 4, 2010, the mission will conduct an extended encounter with Hartley 2, studying the comet using all three of the spacecraft’s instruments (two telescopes with digital colour cameras and an infrared spectrometer).

On its original mission, the Deep Impact fly-by spacecraft had a companion probe spacecraft that was smashed into comet Tempel 1 to reveal for the first time the inner material of a comet.

Although scientific objectives have never been a primary purpose of the Deep Impact/EPOXI spacecraft’s fly-bys of Earth, the mission team has used the spacecraft’s instruments to find clear evidence of water on the Moon and to study light reflected from Earth as a template that scientists eventually may be able be use to identify Earth-like planets around other stars.

Adapted from information issued by the University of Maryland / NASA / JPL-Caltech / UMD / Pat Rawlings.

Was Venus once habitable?

Artist’s concept of lightning on Venus

If Venus had more water in its distant past, could it have been a habitable planet like Earth?

  • Venus might once had have more water
  • Water split by sunlight; hydrogen/oxygen escaped to space
  • If it was wetter, could it have had life?

The Venus Express spacecraft is helping planetary scientists investigate whether Venus once had oceans. If it did, it may even have begun its existence as a habitable planet similar to Earth.

These days, Earth and Venus seem completely different. Earth is a lush, clement world teeming with life, whilst Venus is hellish, its surface roasting at temperatures of a furnace.

Venus in the ultraviolet

Sunlight breaks up water molecules in Venus' clouds, letting hydrogen and oxygen atoms to escape into space.

But underneath it all the two planets share a number of striking similarities. They are nearly identical in size and now, thanks to the European Space Agency’s (ESA) Venus Express orbiter, planetary scientists are seeing other similarities too.

“The basic composition of Venus and Earth is very similar,” says Håkan Svedhem, ESA Venus Express Project Scientist.

One difference stands out—the planet has very little water. Were the contents of Earth’s oceans to be spread evenly across Venus, they would create a layer 3km deep. If you were to condense the current amount of water vapour in Venus’ atmosphere onto its surface, it would create a global puddle just 3cm deep.

Water lost into space

Yet there is another similarity here. Billions of years ago, Venus probably had much more water. Venus Express has confirmed that the planet has lost a large quantity of water into space.

This happens because ultraviolet radiation from the Sun streams into Venus’ atmosphere and breaks the water molecules into their atoms—two of hydrogen and one of oxygen. These then escape to space.

Venus Express has measured the rate of this escape and confirmed that roughly twice as much hydrogen is escaping as oxygen. It’s therefore thought that water is the source of these escaping atoms.

It has also shown that a heavy form of hydrogen, called deuterium, is enriched in the upper echelons of Venus’s atmosphere, because the heavier hydrogen finds it harder to escape the planet’s grip.

Artist's impression of the Venus Express spacecraft

The Venus Express spacecraft is helping scientists study the water history of Venus.

“Everything points to there being large amounts of water on Venus in the past,” says Colin Wilson, Oxford University, UK. But that doesn’t necessarily mean there were oceans on the planet’s surface.

No oceans, but life anyway?

Eric Chassefière, Université Paris-Sud, France, has developed a computer model that suggests the water was largely atmospheric and existed only during the very earliest times, when the surface of the planet was completely molten.

As the water molecules were broken into atoms by sunlight and escaped into space, the subsequent drop in temperature probably triggered the solidification of the surface. In other words, no oceans.

Although it is difficult to test this hypothesis, it does raise a key question. If Venus ever did possess surface water, could planet have had an early habitable period?

Even if true, Chassefière’s model does not preclude the chance that colliding comets might have brought additional water to Venus after its surface solidified, and these could have created bodies of standing water in which life may have been able to form.

Adapted from information issued by ESA / MPS / DLR / IDA / J. Whatmore.