RSSArchive for July, 2011

Australia from Space: Part 3

Lake Acraman seen from space

Lake Acraman sits inside the eroded ruins of an ancient impact crater in the Gawler Ranges in South Australia. Presently about 20 kilometres wide, the original crater could have been up to 85 or 90 kilometres across. It is thought to have formed during the impact of a large meteoroid about 580 million years ago.

AFTER ANTARCTICA, AUSTRALIA IS THE DRIEST continent on Earth, and is largely covered by desert. But even the desert sometimes gets rain, as witnessed by the salt lakes spread throughout the landscape. Although usually dry, they very occasionally can receive water, often as runoff from higher ground.

These amazing images of the Australian ‘outback’were taken by Italian astronaut Paolo Nespoli during his stay aboard the International Space Station.

Lake Cadibarrawirracanna seen from space

According to Wikipedia, Lake Cadibarrawirracanna has the distinction of having the second-longest official place name in Australia. This salt lake is found within the Woomera Prohibited Area in South Australia. Woomera was once a very active rocket launch facility in the 1950s and 1960s. The name Cadibarrawirracanna means 'stars dancing on water'.

Lake Frome seen from space

Another salt lake is Lake Frome, also in South Australia. An ephemeral lake, it spends most of its life dry but sometimes fills with water. According to indigenous Australian Dreamtime mythology, the Rainbow Serpent Akurra drank all the water in the lake.

Lake Noondie seen from space

Lake Noondie, another salt lake, is located in the remote Murchison area of Western Australia.

Terrain near Lake Willis seen from space

This looks like an amazing piece of artwork, or maybe stained tissue cells under a microscope. In fact, what we see here is the dramatic red landscape near Lake Willis in Western Australia.

Red sand dunes in Western Australia, seen from space

Another apparent artwork, this time red sand dunes in outback Western Australia. Fuffy white clouds show there is some moisture in the air.

Earlier Australia from Space pictorials:

Australia from Space: Part 1

Australia from Space: Part 2

Adapted from information issued by ESA / NASA.

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Cosmic expansion rate confirmed

Galaxy cluster

As the universe expands, galaxies move further apart from one another. The rate at which the expansion is proceeding is determined by the Hubble constant, which has been newly measured with high precision.

  • Hubble constant used to gauge size and age of the universe
  • Previous measurements had a level of uncertainty
  • New measurement method confirms earlier results

A STUDENT WITH THE with the International Centre for Radio Astronomy Research (ICRAR) at the University of Western Australia, has calculated how fast the Universe is growing by measuring the Hubble constant.

“The Hubble constant is a key number in astronomy because it’s used to calculate the size and age of the Universe,” said PhD candidate Mr Florian Beutler.

As the Universe expands, it carries other galaxies away from ours. The Hubble constant links how fast the galaxies are moving with how far they are away from us.

By analysing light coming from a distant galaxy, the speed and direction of that galaxy can be easily measured. But determining the galaxy’s distance from Earth is much more difficult.

Until now, this has been done by measuring the brightness of individual objects (such as certain kinds of stars) within a galaxy and using what we know about those objects to calculate how far away the galaxy must be.

This approach is based on some well-established assumptions but is prone to systematic errors, leading Mr Beutler to tackle the problem using a completely different method.

Plot of 6df Galaxy Survey data

In this plot of 125,000 galaxies from 6df Galaxy Survey data, each dot is a galaxy and Earth is at the centre. (The dark slices are regions blocked from view.) The amount of galaxy clustering has been used (along with other data) to measure the expansion rate of the universe.

New method uses super survey

Published in the Monthly Notices of the Royal Astronomical Society, Mr Beutler’s work draws on data from a survey of more than 125,000 galaxies carried out with the UK Schmidt Telescope in eastern Australia.

Called the 6dF Galaxy Survey, this is the biggest survey of relatively nearby galaxies, covering almost half the sky.

Galaxies are not spread evenly through space, but are clustered. Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early Universe, Mr Beutler has measured the Hubble constant with an uncertainty of less than 5%.

The new measurement is 67.0 (±3.2) kilometres per second per megaparsec. A megaparsec is 1 million parsecs, or 3.26 million light-years.

Good agreement

“This way of determining the Hubble constant is as direct and precise as other methods, and provides an independent verification of them,” says Professor Matthew Colless, Director of the Australian Astronomical Observatory and one of Mr Beutler’s co-authors.

“The new measurement agrees well with previous ones, and provides a strong check on previous work.”

The measurement can be refined even further by using data from larger galaxy surveys.

“Big surveys, like the one used for this work, generate numerous scientific outcomes for astronomers internationally,” says Professor Lister Staveley-Smith, ICRAR’s Deputy Director of Science.

Adapted from information issued by ICRAR / Images courtesy ICRAR / Chris Fluke, Centre for Astrophysics & Supercomputing, Swinburne University of Technology / NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA.

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We are not alone

Trojan asteroid 2010 TK7

Trojan asteroid 2010 TK7 (circled in green) orbits the Sun ahead of the Earth. This single frame was taken by NASA's Wide-field Infrared Survey Explorer, or WISE. The majority of the other dots are stars or galaxies far beyond our Solar System.

  • Trojan asteroid found orbiting ahead of Earth
  • 80 million kilometres from our planet
  • No danger of it colliding with us

ASTRONOMERS STUDYING OBSERVATIONS taken by NASA’s Wide-field Infrared Survey Explorer (WISE) mission have discovered the first known ‘Trojan’ asteroid orbiting the Sun along with Earth.

Trojans are asteroids that share an orbit with a planet near stable points in front of or behind the planet. Because they constantly lead or follow in the same orbit as the planet, they never can collide with it.

In our Solar System, Trojans also share orbits with Neptune, Mars and Jupiter. Two of Saturn’s moons even have Trojans.

Hard to see

Scientists had predicted Earth should have Trojans, but they have been difficult to find because they are relatively small and appear near the Sun from Earth’s point of view.

“These asteroids dwell mostly in the daylight, making them very hard to see,” said Martin Connors of Athabasca University in Canada, lead author of a new paper on the discovery in the July 28 issue of the journal Nature.

“But we finally found one, because the object has an unusual orbit that takes it farther away from the Sun than what is typical for Trojans,” added Connors. “WISE was a game-changer, giving us a point of view difficult to have at Earth’s surface.”

Artist's impression of the WISE space telescope

Artist's impression of the WISE space telescope

Thousands of asteroids found

The WISE telescope scanned the entire sky in infrared light from January 2010 to February 2011.

Connors and his team began their search for an Earth Trojan using data from NEOWISE, an extension to the WISE mission that focused in part on near-Earth objects, or NEOs, such as asteroids and comets.

NEOs are bodies that pass within 45 million kilometres of Earth’s path around the Sun.

The NEOWISE project saw more than 155,000 asteroids in the main belt between Mars and Jupiter, and more than 500 NEOs, including 132 that were previously unknown.

Unusual orbit

The team’s hunt resulted in two Trojan candidates. One, called 2010 TK7, was confirmed as an Earth Trojan after follow-up observations with the Canada-France-Hawaii Telescope in Hawaii.

The asteroid is roughly 300 metres in diameter. It has an unusual orbit that traces a complex motion near a stable point in the plane of Earth’s orbit, although the asteroid also moves above and below the plane.

The object is about 80 million kilometres from Earth.

The following video shows how the asteroid continually loops above and below Earth’s orbital plane, while always remaining ahead of our planet:

No danger to Earth

The asteroid’s orbit is well-defined, and for at least the next 100 years it will not come closer to Earth than 24 million kilometres.

“It’s as though Earth is playing follow the leader,” said Amy Mainzer, the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Earth always is chasing this asteroid around.”

A handful of other asteroids also have orbits similar to Earth. Such objects could make excellent candidates for future robotic or human exploration.

Asteroid 2010 TK7 is not a good target because it travels too far above and below the plane of Earth’s orbit, which would require large amounts of fuel to reach it.

More information: WISE mission

Adapted from information issued by NASA / JPL-Caltech / UCLA / Paul Wiegert, University of Western Ontario.

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Earth from Space — Outback crater

The Shoemaker Impact Structure in Western Australia, seen from orbit.

The Shoemaker Impact Structure in Western Australia, seen from orbit.

THE SHOEMAKER (FORMERLY TEAGUE) IMPACT STRUCTURE—located in Western Australia in a drainage basin south of the Waldburg Range—presents an other-worldly appearance in this photograph taken by an astronaut aboard the International Space Station.

The Shoemaker impact structure is approximately 30 kilometres in diameter and clearly defined by concentric ring structures formed in sedimentary rocks (brown to dark brown, image centre).

The structure is thought to have formed following the impact of a large meteoroid approximately 1.63 billion years ago, although some age-dating analyses of rocks at the core of the structure have called this age into question.

Several saline and ephemeral lakes—Nabberu, Teague, Shoemaker, and numerous smaller ponds—are found between the ring structures. Differences in colour result from both water depth and from suspended sediments, with some bright salt crusts visible around the edges of smaller ponds (image centre).

The Teague Impact Structure was renamed Shoemaker in honour of Dr Eugene M. Shoemaker (1928-1997), a pioneer in impact crater studies and planetary geology, as well as the founder of the Astrogeology Branch of the US Geological Survey. Dr Shoemaker (and his wife, Carolyn) made many trips to Australia to scout out impact craters. He died tragically in a head-on car collision during one of those expeditions.

Astronaut photograph provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Centre. Text adapted from information issued by William L. Stefanov, Jacobs/ESCG at NASA-JSC.

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Tribute to the shuttle

http://youtu.be/b9VXeqzqqss

THE SPACE SHUTTLE IS PERHAPS the most complex technological system ever built. In 30 years, it has launched 135 times and helped humankind to dispatch and partially even return many satellites and deep-space probes, to build the International Space Station and to conduct out-of-this-world science. The shuttle has transported also 24 European astronauts to Earth orbit on 25 missions.

This short video highlights the flights that had a European flavour—from STS-9 in 1983 to STS-134 in May 2011.

Adapted from information issued by ESA.

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Radio astronomy protected in Western Australia

Artist's impression of dishes that will make up the SKA radio telescope.

Artist's impression of dishes that will make up the SKA radio telescope.

ENHANCED PROTECTIONS are now in place for the Mid West Radio Quiet Zone (RQZ) in remote Western Australia (near Boolardy Station), around 200 kilometres east of Meekatharra…a candidate site for the proposed Square Kilometre Array (SKA).

The RQZ was established in 2005 to provide an environment that protects highly sensitive equipment used for radio astronomy from unwanted radio communications signals.

These arrangements protect the radio telescopes currently in place at the Murchison Radioastronomy Observatory—such as the Australian SKA Pathfinder (ASKAP) and the Murchison Wide-field Array (MWA)—as well as those proposed in the Australian-New Zealand bid to host the SKA.

ASKAP dish

One of the Australian SKA Pathfinder (ASKAP) dishes.

“A clear regulatory framework to support radio quiet arrangements will further assist Australia to create the world’s best radioastronomy facility,” said Australian Communications and Media Authority (ACMA) Chairman, Chris Chapman.

“This will provide a platform that should be ideal for future radioastronomy projects, including the €1.5 billion SKA project.”

Mr Chapman said the new protection measures provide greater clarity and certainty to the arrangements that protect radio astronomy services in the RQZ.

‘The new measures continue to provide for radio quiet while supporting the use of spectrum by other users and placing the lowest feasible burden on industry in the region,’ said Mr Chapman.

The introduction of the enhanced protections for the RQZ follows a very extensive consultation process in which the ACMA sought the views of interested stakeholders.

More information: ACMA Planning for the radio astronomy service

Adapted from information issued by ACMA. Images courtesy SPDO / Swinburne Astronomy Productions / CASS / Terrace Photographers.

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Shuttle is dead — long live the MPCV

AS NASA CLOSES THE CHAPTER on the space shuttle programme, a new era of exploration vehicles is beginning to take off.

Testing began this month in the new Hydro Impact Basin at NASA’s Langley Research Centre, to certify the Orion Multi-Purpose Crew Vehicle (MPCV) for water landings.

The Orion MPCV will carry astronauts into space, provide emergency abort capability, sustain the crew during space travel and ensure safe re-entry and landing.

Engineers have dropped a 10-tonne MPCV mock-up into the basin. The test item is similar in size and shape to MPCV, but is more rigid so that it can withstand multiple drops.

Each test has a different drop velocity to represent the MPCV’s possible entry conditions during water landings.

The last of three drop tests to verify the new facility is scheduled for the end of this month.

Testing will resume in September with a slightly modified test article that is more representative of the actual MPCV.

The new Hydro Impact Basin is 35 metres long, 27 metres wide and 6 metres deep. It is located at the west end of Langley’s historic Landing and Impact Research Facility, or Gantry, where Apollo astronauts trained for moonwalks.

Here’s an overview video of the Orion MPCV programme:

http://youtu.be/ClupWQ6NdBM?hd=1

Adapted from information issued by NASA.

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Exoplanets have unearthly light shows

Artist's concept of a 'hot Jupiter' planet

Artist's concept of a 'hot Jupiter' planet with two moons and a Sun-like star. The planet is cloaked in brilliant aurorae—100-1000 times brighter than Earth's—triggered by stellar storms.

BEINGS LIVING ON ‘HOT JUPITER’ PLANETS could be treated to a dazzling nightly light show a thousand times better than Earth’s Northern and Southern Lights.

Earth’s aurorae provide a dazzling light show to people living in the polar regions, with shimmering curtains of green and red undulating across the sky like a living creature.

But new research shows that aurorae on ‘hot Jupiter’ planets closely orbiting distant stars could be 100-1000 times brighter than Earthly aurorae. They also would ripple from equator to poles (due to the planet’s proximity to any stellar eruptions), treating the entire planet to an otherworldly spectacle.

“I’d love to get a reservation on a tour to see these aurorae!” said lead author Ofer Cohen, a SHINE-NSF postdoctoral fellow at the Harvard-Smithsonian Centre for Astrophysics (CfA).

Gigantic stellar blasts

Earth’s aurorae are created when energetic particles from the Sun slam into our planet’s magnetic field. The field guides the particles toward the poles, where they smash into Earth’s atmosphere, causing air molecules to glow like a neon sign.

The same process can occur on planets orbiting distant stars, known as exoplanets.

Aurora Australis seen from the International Space Station

The Southern Lights or Aurora Australis seen from the International Space Station on July 14, 2011.

Particularly strong aurorae result when Earth is hit by a coronal mass ejection or CME—a gigantic blast that sends billions of tonnes of solar plasma (electrically charged, hot gas) into the Solar System.

A CME can disrupt Earth’s magnetosphere—the bubble of space protected by Earth’s magnetic field—causing a geomagnetic storm. In 1989, a CME hit Earth with such force that the resulting geomagnetic storm blacked out huge regions of Quebec.

Planets in the firing line

Cohen and his colleagues used computer models to study what would happen if a gas giant planet in a close orbit, just a few million kilometres from its star, were hit by a stellar eruption.

He wanted to learn the effect on the exoplanet’s atmosphere and surrounding magnetosphere.

The alien gas giant would be subjected to extreme forces. In our Solar System, a CME spreads out as it travels through space, so it’s more diffuse once it reaches us.

Aurora planet animation

In this animation, stunning aurorae (pink/purple) ripple around a 'hot Jupiter' planet.

A ‘hot Jupiter’ would feel a stronger and more focused blast, like the difference between being 100 kilometres from an erupting volcano or one kilometre away.

“The impact to the exoplanet would be completely different than what we see in our Solar System, and much more violent,” said co-author Vinay Kashyap of CfA.

Yet despite the extreme forces involved, the exoplanet’s magnetic field would shield its atmosphere from erosion.

Too close for comfort

This work has important implications for the habitability of rocky worlds orbiting distant stars. Since red dwarf stars are the most common stars in our galaxy, astronomers have suggested focusing on them in the search for Earth-like worlds.

However since a red dwarf is cooler than our Sun, a rocky planet would have to orbit very close to the star to be warm enough for water to exist as a liquid. There, it would be subjected to the sort of violent stellar eruptions Cohen and his colleagues studied.

Their future work will examine whether rocky worlds could shield themselves from such eruptions.

Adapted from information issued by the Harvard-Smithsonian Centre for Astrophysics. Images courtesy David A. Aguilar (CfA). Animation produced by Hyperspective Studios.

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Earth from Space —Triple trouble in the Atlantic

Satellite image of a trio of storms in the Atlantic

A trio of storms in the Atlantic, spotted by the GOES-13 weather satellite.

A WEATHER SATELLITE captured a triple-header in the tropics when it snapped three tropical cyclones in one image in the Northern Hemisphere.

The image—taken by the GOES-13 satellite on July 20—shows a consolidating low pressure area called System 99L in the eastern North Atlantic Ocean, Tropical Storm Bret several hundred kilometres east of South Carolina, and Hurricane Dora off the west coast of Mexico.

The image was created by the NASA/NOAA GOES Project at NASA’s Goddard Space Flight Centre.

System 99L is a low-pressure area that may reach tropical depression status in the next day or two. It is located about 900 kilometres east-northeast of Bermuda and is moving to the northeast at 32 kilometres per hour.

The US National Hurricane Centre gave System 99L a 90 percent chance building to a tropical depression in the following 48 hours.

Text adapted from information issued by Rob Gutro, NASA Goddard Space Flight Centre. Image courtesy NASA / NOAA GOES Project, Dennis Chesters.

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Shuttle re-entry seen from space!

ISS photo of space shuttle Atlantis re-entering Earth's atmosphere

The glowing wake of space shuttle Atlantis as she re-entered the atmosphere for the final time.

THESE AMAZINGS VIEWS of the space shuttle Atlantis—looking like the track of a firefly against clouds and city lights—on its way home, were snapped by the Expedition 28 crew aboard the International Space Station. Airglow over Earth can be seen in the background.

ISS photo of space shuttle Atlantis re-entering Earth's atmosphere

Another view of Atlantis' re-entry.

ISS photo of space shuttle Atlantis re-entering Earth's atmosphere

Atlantis disappears over the horizon.

Adapted from information issued by NASA.

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