RSSArchive for April, 2012

Australian SKA site producing the goods

  • Western Australia radioastronomy site now active
  • Already producing world-class research
  • Targets are as close as the Moon and as distant as quasars

CSIRO’s MURCHISON RADIOASTRONOMY OBSERVATORY (MRO), located in remote Western Australia, is the site proposed by Australia and New Zealand to host the high-density core of the multi-billion dollar Square Kilometre Array (SKA), and is already producing world-class research that will be described at an international conference in the UK this week.

The research uses the Murchison Widefield Array (MWA), a $50m SKA Precursor telescope located at the MRO. The MWA project is led by the International Centre for Radio Astronomy Research (ICRAR) at Curtin University.

MWA Project Director, Professor Steven Tingay, will be presenting the results at an international conference in the UK last week, and said, “The MWA is just starting to come online but is already producing world-class research, due to the extraordinarily high quality of the MRO as a location for ultra-sensitive radio telescopes.”

The MWA uses stationary antennae that look like strange metallic spiders, with no moving parts. There will be 128 groups of 16 antennae, each group known as a “tile”. The system will use huge computing power to undertake sensitive surveys of the cosmos.

An MWA antennae tile group

Unlike the CSIRO's Parkes "dish", the Murchison Widefield Array uses strange-looking antennae space out on the ground. Seen here are three groups of 16 antennae. The system will use 128 groups.

Low interference level

Professor Tingay said that a critical requirement for the MWA is the need to operate in an environment free from radio interference generated by human activities. FM radio stations, mobile phones, cars and industrial activities are major sources of interference that drown out the whisper-faint radio signals from objects in the distant universe.

“For this reason, the MWA has been constructed at the MRO, where the level of interference is much lower than most other observatory locations around the world. An indication of the MRO site’s pristine conditions is the amount of data that is lost due to interference. At the MRO this is less than 1%, compared to close to 100% at some other observatory locations around the world,” said Tingay.

Due for completion November this year, the MWA already has a steady flow of research from it’s current configuration due to the excellent radio-quiet conditions of the MRO.

Recently, astronomers from MIT in Cambridge, Massachusetts, have used the MWA to image an area of the sky 20,000 times larger than the full Moon, covering a region of the universe that the MWA will search for the very first stars and galaxies to form, soon after the Big Bang. Researchers from the University of Washington have determined that the MWA should be capable of detecting these signals.

Aside from these papers, an avalanche of astrophysics research from the MWA is about to appear in print, ranging from studies of explosions on the Sun, to observations of signals bouncing off the Moon, to surveys looking for highly variable quasars.

The MWA is being delivered by an international consortium of 13 institutions in four countries: Australia; the USA; India; and New Zealand.

More information: Murchison Widefield Array

Adapted from information issued by ICRAR. Photography by Paul Bourke and Jonathan Knispel (supported by WASP (UWA), iVEC, ICRAR, and CSIRO).

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Views of Moons

NASA’S CASSINI SPACECRAFT, in orbit around the planet Saturn, has been sending back some wonderful views of its moons. In particular, it has captured images where one moon seems to float in front of the other. Here we present a selection of recent images.

Cassini image of Titan and Tethys

Can you tell which of these moons in the foreground? It's Titan, the large one (diameter 5,150 kilometres; bigger than our Moon) with the orange atmosphere, with smaller, shiny, icy Tethys in the background. Titan was 2.3 million kilometres from Titan, and 3.4 million from Tethys when it took this image. Saturn's rings can be seen edge-on in the distance.

Cassini image of Rhea and Titan

This black-and-white image shows the moon Rhea (1,528 km diameter) in front of Titan. Cassini was 2 million kilometres from Titan and 1.3 million kilometres from Rhea when it took this image.

Cassini image of Titan and Dione

This view shows Titan again, this time with the much smaller moon Dione (1,123 km diameter) peering around from behind, with Saturn and its rings (edge-on) in the background. Cassini was 2.3 million kilometres from Titan and 3.2 million kilometres from Dione when it took the image. The haze that surrounds Titan can clearly be seen. Titan has a mostly nitrogen atmosphere that extends far from the surface. The surface pressure is about 1.5 times that on Earth.

Cassini image of Titan

In this view, Titan appears to float in front of Saturn and its rings. Titan is not only the second-largest moon in the Solar System; it's also about 300 kilometres wider than the planet Mercury!

More information: Cassini mission

Story by Jonathan Nally. Images courtesy NASA / JPL-Caltech / Space Science Institute.

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Must-see video of the Sun!

THIS TWO-MINUTE VIDEO shows highlights from the Solar Dynamics Observatory’s second year of studying our nearest star. The NASA spacecraft takes continuous imagery at many wavelengths, providing an unprecedented insight into the life and times of the Sun.

Story by Jonathan Nally. Imagery courtesy NASA / Goddard Space Flight Centre Scientific Visualisation Studio

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In the footsteps of Apollo 11

LRO image of the Apollo 11 landing site

NASA's Lunar Reconnaissance Orbiter took this image of the Apollo 11 landing site, showing the equipment left on the surface of the Moon.

NASA’S LUNAR RECONNAISSANCE ORBITER spacecraft took this amazing image from an altitude of just 24 kilometres above the surface of the Moon. It shows the descent stage of the Apollo 11 lunar module, right where Neil Armstrong and Buzz Aldrin left it in July 1969. Also visible are the instrument packages the two astronauts set out on the lunar surface not far from the lunar module.

So take that, Moon landing conspiracy theorists!

Visible are dark squiggly lines joining the various man-made objects. These are the tracks left by the astronauts as their boots scuffed up the powdery lunar dust.

The LRRR was the Laser Ranging RetroReflector, a device that contained “corner reflectors”—special lenses that send a light beam back out in the same direction it enters. Scientists fired laser beams at the LRRR and timed how long it took for the signals to return to Earth, enabling them to make incredibly accurate measurements of the distance to the Moon.

And because the LRRR is a passive device with no electrical requirements and no moving parts, it is still used today.

Also visible is the Passive Seismic Experiment Package(PSEP), a seismometer that detected “moonquakes” and the impact of spacecraft and radioed the data back to Earth.

Apollo 11 surface image showing the lunar module and Little West crater

Neil Armstrong (whose shadow can be seen at left) ran over to take a look at Little West crater, about 50 metres from the lunar module.

You can see a trail leading to the crater (called Little West) on the right of the lunar module. This is where Neil Armstrong ran over to take a look. The distance is about 60 metres, and marks the furthest point either of the astronauts ventured from the lunar module.

(Take a look at this Apollo Lunar Surface Journal page for a more detailed image.)

Astronauts on later missions were far less constrained in their movements, as they had more time for their spacewalks. In addition, the final three Apollo mission carried lunar rovers that enabled their astronauts to travel further.

Story by Jonathan Nally. Images courtesy NASA.

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Hubble’s birthday view of starbirth nebula

Hubble image of 30 Doradus

The amazing twirls and swirls of 30 Doradus, a starbirth region of gas and stars located in the Large Magellanic Cloud galaxy 170,000 light-years from Earth.

IT SEEMS HARD TO BELIEVE, but the Hubble Space Telescope has now been in orbit for 22 years. In that time it has advanced our understanding of the universe overall and of the stars, galaxies and nebulae within it.

To celebrate it’s birthday, Hubble scientists have released stunning new views of a “starbirth” region deep in the southern sky, known as 30 Doradus.

30 Doradus is part of the Tarantula Nebula, so-called for its resemblance to a spider, with tendrils of interstellar gas extending in many directions.

The Tarantula is located within the Large Magellanic Cloud galaxy, a close neighbour of the Milky Way about 170,000 light-years distant.

The main Hubble image is made up of many separate images “stitched” together. In fact, it is one of the largest Hubble images ever produced, and at the distance of the Tarantula covers a field 650 light-years across.

This starbirth region is home to numerous stars, young and old, big and small. Near the nebula’s heart is a star cluster called R136. It used to be thought that R136 contained the largest known star in the universe, R136a at 1,500 the mass of the Sun. It has since been determined, however, that R136a is itself a tight cluster of stars. Nevertheless, one of those stars, R136a1, is still the largest known at 265 times the mass of the Sun and 8,700,000 it’s brightness.

The radiance from all the stars has carved out intricate voids and valleys within the surrounding gas, and in some cases formed shockwaves or regions of increased gas density that could be triggering the inward collapse of gas clumps to form new stars.

See more and larger images of 30 Doradus at HubbleSite.

Close-up of part of 30 Doradus

This close-up of part of 30 Doradus shows a huge cavity in the gas, carved out by the stellar wind of young, powerful stars.

Hubble image of star cluster Hodge 301

This tight, bright cluster of stars within 30 Doradus is called Hodge 301. Unlike many of the youthful stars in 30 Doradus, many of those in Hodge 301 are ageing, red supergiants.

NGC 2070 with R136

At the heart of this portion of 30 Doradus lies the star cluster R136, which contains many of the heaviest known stars in the local universe.

Story by Jonathan Nally. Images credit: NASA, ESA, D. Lennon and E. Sabbi (ESA/STScI), J. Anderson, S. E. de Mink, R. van der Marel, T. Sohn, and N. Walborn (STScI), N. Bastian (Excellence Cluster, Munich), L. Bedin (INAF, Padua), E. Bressert (ESO), P. Crowther (University of Sheffield), A. de Koter (University of Amsterdam), C. Evans (UKATC/STFC, Edinburgh), A. Herrero (IAC, Tenerife), N. Langer (AifA, Bonn), I. Platais (JHU), and H. Sana (University of Amsterdam), and the Hubble Heritage Team (STScI/AURA)

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Cargo capsule set for launch

Artist's impression of the Dragon spacecraft in orbit.

Artist's impression of the Dragon spacecraft in orbit.

AT THE CAPE CANAVERAL Air Force Station (adjacent to the Kennedy Space Centre) in Florida, final preparations are being made for a historic launch at the end of this month.

The unmanned Dragon capsule and its Falcon 9 rocket, both privately developed by the SpaceX corporation, are due for launch on April 30 (USA time) on a combined test flight and cargo flight to the International Space Station (ISS).

NASA is providing seed money to SpaceX and a second company, Orbital Sciences, to develop and operate unmanned craft that can keep the ISS resupplied in the post-shuttle era.

SpaceX is intending to field a manned version of Dragon later this decade, capable of taking seven astronauts into low Earth orbit.

More information: NASA Commercial Orbital Transportation System

Dragon capsule is placed atop its cargo ring

Dragon capsule is mated to a "ring" that will sit on top of the Falcon 9 rocket.

Falcon 9 rocket in inside a processing hangar at Cape Canaveral Air Force Station.

Falcon 9 rocket in inside a processing hangar at the Cape Canaveral Air Force Station.

Falcon 9 rocket on the launch pad at the Cape Canaveral Air Force Station

Falcon 9 rocket with Dragon capsule attached on top sits fully fuelled on Space Launch Complex-40 at Cape Canaveral Air Force Station in Florida during a launch dress rehearsal.

Story by Jonathan Nally. Images courtesy NASA / Gianni Woods / Jim Grossmann / Kim Shiflett.

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Australian research into “space glass”

Light shining through fibre optics

Fibre optics technology could be revolutionised by Queensland University of Technology space research.

RESEARCHERS AT THE Queensland University of Technology’s (QUT) Science and Engineering Faculty are about to experiment with a special kind of glass made under weightless conditions.

Called ZBLAN, it forms improperly under gravity but could theoretically be made into a super-fibre in the absence of gravity.

Dr Martin Castillo, researcher for QUT’s micro-gravity drop tower, will work with the US Air Force to conduct first-of-its-kind researchinto ZBLAN.

ZBLAN glass made in microgravity and normal gravity

ZBLAN glass made in microgravity (left) and normal gravity (right). The difference is obvious.

“This glass contains a variety of heavy metals that upon cooling create internal stresses which leads to crystallization of the material, an undesired property for glass,” said Dr Castillo. “The synthesis of this material in the absence of gravity has the ability to overcome this barrier.”

Theoretically, ZBLAN fibres would have the lowest amount of signal loss of any optical known substance. This means signals could be sent over much longer distances before needing to be boosted by power-hungry amplifiers. It would also provide increased bandwidths.

“Although this glass has been made in a few places, no one has yet figured out how to draw it into a fibre,” Dr Castillo said.

“I previously spent two years working in Japan trying to produce this glass via gas levitation and with a fibre pulling apparatus in zero gravity and was unsuccessful,” he added. “Now I think we’ve been able to formulate very new and different techniques to that used by anyone in the world.”

Initial experiments will be conducted using QUT’s drop tower. A drop tower is a vertical column, from the top of which samples can be dropped…gaining a few seconds of weightlessness—or more properly, “microgravity”—on the way down.

For the ZBLAN drops, samples will experience about 2.1 seconds of microgravity.

Left: Dr Martin Castillo at the base of QUT's micro-gravity tower. Right: Two views inside the drop tower.

Left: Dr Martin Castillo at the base of QUT's micro-gravity tower. Right: Two views inside the drop tower.

This is just a foretaste though. Dr Castillo intends to conduct further experiments aboard NASA’s “Vomit Comet”, an aircraft that flies parabolic trajectories to produce a short period of microgravity.

And following that, a further experiment will be launched into space in 2013 aboard a US Air Force suborbital rocket. This will be the first QUT experiment to be lofted above the atmosphere.

“In order to stay at the leading edge of the synthesis of specialised glass, all traditional methods have to be abandoned,” Dr Castillo said.

Story by Jonathan Nally. Photos courtesy QUT / NASA.

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Australia from Space: Menindee Lakes

Astronaut image of Menindee Lakes

Menindee Lakes, as photographed by astronauts aboard the International Space Station.

IN THE FAR WEST of New South Wales, Australia, near the town of Menindee, a system of ephemeral, freshwater lakes are fed by the Darling River when it floods. Lake Tandou is the longest, at 18.6 kilometres from north to south. The Darling River itself was flowing in December 2011 when this image was made.

The Darling River flows southwest in tortuous fashion across the flat landscapes of this part of Australia. It has created several inland deltas in its course to the sea, with characteristic diverging channel patterns marked by younger sediments that appear greyer than the ancient red soils and rocks surrounding them.

One inland delta appears at image right, where minor channels wind across the countryside. The apex of another inland delta appears at image lower left.

Some of the Menindee Lakes have been incorporated into an artificially regulated overflow system providing for flood control, water storage for domestic use and livestock, and downstream irrigation.

The floor of Lake Tandou is used as prime agricultural land, as evidenced by its patchwork of irrigated fields that are protected from flooding. The lakes also serve as important wetlands supporting a rich diversity of birds.

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

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VIDEO: The road to Mars

WHAT DOES IT TAKE to get a spacecraft from Earth all the way to Mars? There are a few key things to consider, as explained in this 60-second video from NASA’s Jet Propulsion Laboratory.

Adapted from information issued by NASA / JPL / Caltech.

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NEW PRODUCT: Vixen Polarie Star Tracker

Graphic of Vixen Polarie with sky photograph background

The easy-to-use Vixen Polarie star tracker lets you take impressive long-exposure images of the night sky.

WOULD YOU LIKE TO TAKE YOUR OWN sky photographs but don’t have a telescope? The new Vixen Polarie Star Tracker lets anyone with a digital SLR (and some digital compact cameras) take impressive wide-angle sky shots with ease.

To get the best sky shots, you need to take exposures that are much longer than the fraction of a second typically used for daylight terrestrial photographs. You might need anything from tens of seconds up to tens of minutes.

The problem is that the Earth is turning, and this makes everything in the sky seem to move through the field of view of your camera, resulting in stars that look like streaks of light instead of fine pinpoints.

What you need is a way to move your camera to track the movement of the sky. The traditional way to do this is to set up a telescope, carefully align it with the Earth’s rotation (ie. the angle up from the horizon and pointed directly south or north), and piggyback your camera on it.

But this can be a lot of hassle, and most people don’t cart their telescope around when they go on holidays.

Enter the Vixen Polarie Star Tracker, which is designed to be used without a telescope. The Polarie sits between your tripod and your camera. Simply angle it upwards according to your latitude (using the easy-to-read scale on the side), point it south (for the Southern Hemisphere) or north (N. Hemisphere) using the inbuilt compass, and you’re ready to go!

The Vixen Polarie's features
How to set up the Vixen Polarie

The Vixen Polarie sits between your tripod and your camera. Alignment is as easy as adjusting the vertical angle for your latitude, and using the in-built compass to find north or south.

The battery-powered unit swivels your camera at the same rate as the Earth turns, tracking the moving sky and letting you take long-exposure images to bring out detail and colour.

The unit is compact and portable, and because it attaches to any standard tripod, you don’t need any extra gear…although Vixen does make a purpose-built tripod and handy carry bag to give you a complete system.

The Polarie already has received rave reviews—and here are some examples of shots taken using it:

Image of nebulosity

With the appropriate lens, you can take dramatic shots of deep sky objects.

The Orion Nebula

A tracked photo of the famous Orion Nebula using the Vixen Polarie.

Wide-angle view of Orion

A wide-angle view of the constellation Orion, with the Orion Nebula in the centre.

Wide-angle view of the Milky Way

Wide-angle views of the Milky Way are popular amongst astrophotographers, and are now much easier to achieve using the Vixen Polarie.

This sort of tracking unit is ideally suited to producing those beautiful wide-angle shots of the sky we all admire so much, especially of the Milky Way. It’ll also be incredibly useful during the upcoming November 14 total solar eclipse.

Powered by two AA batteries or via USB, the Polarie can carry up to 2kg (camera or spotting scope).

The Vixen Polarie is available in Australia exclusively through AstroShop.com.au.

You can also get a complete package of the Polarie plus a Velbon tripod and custom carry bag.

Story by Jonathan Nally. Photos courtesy Vixen.

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