Posted on by Fraser Cain

Jupiter Gets Even More Satellites

Image credit: UBC

A team of Canadian astronomers have discovered even more new satellites for Jupiter, giving the giant planet a total of 61 moons – 21 were discovered just this year. These new satellites are harder to detect because they’re only 1-5 kilometres across and have wide, irregular orbits around Jupiter. The team took a mosaic of images around the entire sky of Jupiter, and then used a computer to search for points of light that had the motion of a Jovian moon.

They were small and hard to find, but with the help of some new telescopic equipment and cameras, UBC professor Brett Gladman, UBC postdoctoral researcher Lynne Allen, and Dr. J.J. Kavelaars of the National Research Council of Canada have discovered nine previously unknown moons of Jupiter. So far this year, 21 new Jupiter moons have been identified.

The discovery of the distant satellites, announced today at the annual meeting of the Canadian Astronomical Society, boosts the number of known moons on Jupiter to 61 — more moons than any other planet in the solar system.

“The discovery of these small satellites is going to help us understand how Jupiter and the other giant planets formed,” said Gladman, a Canada Research Chair in Planetary Astronomy.

The new satellites were a challenge to detect because most are only about 1-5 kilometers in size. The feeble amounts of light they reflect back to earth must compete against the glare of brilliant Jupiter. Their small size and distance from the Sun prevent the satellites from shining any brighter than 24th magnitude, about 100 million times fainter than can be seen with the unaided eye. To locate these new moons, Gladman’s team used the new Megaprime mosaic of CCD cameras at the 3.6m Canada-France-Hawaii telescope on Mauna Kea, Hawaii.

The mosaic camera enabled the team to take three images of the entire sky around Jupiter. They used computer algorithms to search the images for the faint points of light moving across the sky as moons should.

Because moons can sometimes appear in front of distant stars or lost in the light scattered from the planet, to find them requires painstakingly repeating the search several times. The team undertook the task between February and April 2003.

International members of the jovian search team include Cornell University astronomers Phil Nicholson, Joseph A. Burns, and Valerio Carruba, Jean-Marc Petit of the Observatoire de Besancon, and Brian Marsden and Matthew Holman of the Harvard-Smithsonian Center for Astrophysics.

Original Source: UBC News Release

Posted on by Fraser Cain

New Station Modules Arrive in Florida

Image credit: NASA

Two major components of the International Space Station arrived at NASA’s Kennedy Space Center in Florida this week. Node 2, built by the European Space Agency, will increase the station’s living and work space, while the Japanese Experiment Module (JEM) will enhance its research capabilities. NASA engineers will perform integration tests over the course of the summer and then the modules will be moved to the KSC Space Station Processing Facility for a future launch on the space shuttle.

After traveling thousands of miles, two major components of the International Space Station completed the first leg of a journey that will eventually end 240 miles above the Earth. NASA’s Node 2, built for the agency by the European Space Agency (ESA) in Italy, and the Pressurized Module of the Japanese Experiment Module (JEM) arrived in Florida and are
being transported to the Kennedy Space Center (KSC) this week.

“Delivery of these components, built in Europe and Japan, to KSC for integrated testing prior to flight is yet another indication of the significant global cooperation and proactive planning required for successful operation of the International Space Station program,” said Bill Gerstenmaier, NASA’s Station Program Manager. “Their arrival in the United States signifies the Space Station international partnership is continuing to move forward with the steps necessary to construct our unique research platform in space,” he said.

The arrival of Node 2, the next pressurized module to be installed on the Station, sets in motion the final steps toward completing assembly of essential U.S. components. When
installed, Node 2 will increase the living and working space inside the Space Station to approximately 18,000 cubic feet. It will also allow the addition of international laboratories
from Europe and Japan.

The Pressurized Module is the first element of the JEM, named “Kibo” (Hope), to be delivered to KSC. The JEM is Japan’s primary contribution to the Station. It will enhance the unique research capabilities of the orbiting complex by providing an additional environment for astronauts to conduct science experiments.

The JEM also includes an exposed facility (platform) for space environment experiments, a robotic manipulator system, and two logistics modules. The various JEM components will be
assembled in space over the course of three Shuttle missions.

An Airbus Beluga heavy-lift aircraft, carrying Node 2, departed May 30 from Turin, Italy, where the Italian Space Agency’s (ASI) contractor, Alenia Spazio, built it. Following post-transportation inspections, ASI will formally transfer ownership of Node 2 to ESA, which, in turn, will sign it over to NASA.

The container transport ship carrying JEM departed May 2 from Yokohama Harbor in Japan for the voyage to the United States. The National Space Development Agency of Japan (NASDA) developed the laboratory at the Tsukuba Space Center near Tokyo.

Later this summer, integrated testing will confirm module compatibility and, ultimately, lead to pre-launch processing at KSC’s Space Station Processing Facility.

Original Source: NASA News Release

Posted on by Fraser Cain

US and Russia Renew Commitment to the Space Station

Image credit: Whitehouse

During the G-8 summit held in St. Petersburg, President Bush of the US and President Putin of Russia renewed their commitment to the construction and maintenance of the International Space Station and other joint space exploration. A brief statement from the Whitehouse confirmed that each member country would continue its role in the partnership, but was vague about any future spaceflight plans.

The loss of the Space Shuttle Columbia has underscored the historic role of the United States and Russia as partners in space exploration, who have persevered despite tragedy and adversity. During this challenging time, our partnership has deepened and the International Space Station (ISS) program remains strong. The extraordinary efforts of our countries continue. The United States is committed to safely returning the Space Shuttle to flight, and the Russian Federation is committed to meeting the ISS crew transport and logistics resupply requirements necessary to maintain our joint American astronaut and Russian cosmonaut teams on board the ISS until the Space Shuttle returns to flight.

We confirm our mutual aspiration to ensure the continued assembly and viability of the International Space Station as a world-class research facility, relying on our unprecedented experience of bilateral and multilateral interaction in space. We reaffirm our commitment to the mission of human space flight and are prepared to take energetic steps to enhance our cooperation in the application of space technology and techniques.

Posted on by Fraser Cain

Astronomers Begin a Massive Survey of the Milky Way

Image credit: RAVE

Researchers from 11 countries are working together to measure the motion and composition of 50 million stars in the Milky Way. This new survey is called RAVE (Radial Velocity Experiment), and astronomers will be able to use the data gathered to construct a very detailed history of our galaxy. They will be able to determine which widely separated stars were formed at a single location, and help answer competing theories about how our galaxy formed. The pilot phase of the project will begin with the UK Schmidt telescope which can measure 600 stars a night, and then production will pick up as other observatories join the hunt.

Clues to how galaxies formed in the early Universe lie right under our nose – in our own Galaxy. The Galaxy formed by the accretion of infalling satellite galaxies, many astronomers think. Theoretical models of the formation of galaxies predict such a scenario. But not all astronomers are convinced yet and the topic is still controversial.

Now researchers from eleven countries have launched an ambitious project to reconstruct our Galaxy’s history by gathering key components of motion and chemi cal compositions for its apparently brightest 50 million stars.

RAVE (RAdial Velocity Experiment) is an all-sky stellar spectroscopy survey just started on the 1.2-m UK Schmidt telescope in eastern Australia.

Projects such as Hipparcos and Tycho have accurately measured the positions and proper motions – movement across the sky – of more than 2.5 million stars.

But to get a complete picture of stellar motions, and thus to enable astronomers to reconstruct the structure and formation history of our Galaxy, they also need radial velocities – the movement of stars towards or away from the observer. And before RAVE began only about 20,000 stellar radial velocities were in the archives.

RAVE will be able to achieve velocities accurate to within 2 km/s – about 1% of the speed at which stars typically move in the Galaxy.

“With this accuracy and this number of radial velocities we will be able to identify dozens, perhaps hundreds, of streams of stars in the solar vicinity. The streams represent debris from disrupted old satellite galaxies now engulfed by our Galaxy,” said Professor Matthias Steinmetz, Director at the Astrophysical Institute Potsdam and leader of the RAVE science team.

Even after plunging into our Galaxy, the stars of a satellite galaxy continue to move as a coherent group, and can be identified by their common velocity even after billions of years. However, only a very few of those disrupted satellites have been identified to date.

RAVE will also gather the chemical compositions of stars. These should help show which widely separated stars were formed at a common site. They should also determine whether these stars have been formed before or after the satellite galaxy of which they were a part broke up.

“RAVE will help us decide between competing models for the formation of the various structures of the Galaxy, such as the central bulge of stars and the so-called ‘thick disk’,” said Steinmetz.

“For a survey such as this, field of view is more important than aperture. The UK Schmidt telescope is a perfect tool for this work,” said Professor Brian Boyle, Director of the Anglo-Australian Observatory, which operates the telescope. The field of view of the UK Schmidt telescope covers an area more than 100 times larger than that of the Moon.

RAVE’s initial pilot phase is being carried out with the 6dF (six-degree field) instrument on the UK Schmidt. Designed and built by the Anglo-Australian Observatory, the 6dF instrument is a ‘pick and place’ robot that positions 150 fibres on the telescope’s focal plane.

Using 6dF, astronomers can collect up to 600 stellar spectra per night. And by 2005 they plan to have 100,000 – five times as many as have been measured since Hermann Carl Vogel started such work at the Astrophysical Observatory Potsdam in 1888.

In 2006 the pace of data collection will pick up even further, when 6dF instrument is replaced by a radical new instrument from the AAO – UKidna, with 2250 fibres mounted on independently movable spines.

“With UKidna we’ll be taking up to 22,000 spectra on a clear night,” said Boyle.

“Then we’ll be able to push beyond our local Galactic neighbourhood, out into the furthest corners of the Milky Way,” said Professor Rosie Wyse of Johns-Hopkins University in Baltimore.

As well as uncovering the history of our Galaxy, RAVE will establish a huge database of stellar spectra – by far the largest to date.

“This will be a vast resource for studies of the properties and evolution of stars,” said Professor Ulisse Munari of the Padova Observatory in Asagio.

With its large database of stellar spectra RAVE will also provide an ideal training set for the design of future space missions such as the European Space Agency’s cornerstone mission GAIA, which will attempt to measure positions and velocities of up to a billion stars in the Milky Way.

Original Source: AIP News Release

Posted on by Fraser Cain

Gemini Demonstrates Its Adaptive Optics

Image credit: Gemini

The latest image taken by the Gemini telescope in Mauna Kea Hawaii demonstrates how powerful its new adaptive optics technology can be. The telescope captured an image of the globular cluster M-13, first with its normal resolution and then using the Altair adaptive optics system; the second image is crystal clear, and contains many more stars which are finely focused. The adaptive optics compensate up to 1000 times a second for distortions caused by the Earth’s atmosphere, so the light appears as if the telescope was in space. This technology is expected to revolutionize ground-based astronomy.

A razor-sharp image was released today revealing new details at the heart of a famous star cluster. The thousands of swarming stars at the cluster’s core were made visible by an innovative adaptive optics system called Altair (after the star Altair) that is currently being commissioned on the Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawai`i.

Among several of the first images from Altair (Altitude Conjugate Adaptive Optics for Infrared), the high-resolution data reveal multitudes of stars with stunning clarity. The dense star cluster known to generations of skywatchers as the Great Hercules Cluster or M-13 is home to hundreds of thousands of stars that, in the center, are often blurred by our atmosphere into a great glowing mass. “The resolution obtained in these images is approximately equivalent to seeing the separation between an automobile’s headlights on the Golden Gate Bridge in San Francisco while standing 3,850 kilometers away in Hawai`i,” said Observatory Adaptive Optics Scientist Dr. Francois Rigaut.

The close-up images of M-13, with and without Altair, as well as a spectacular reference image of the entire cluster, provided by the Canada-France-Hawaii Telescope, can be viewed and downloaded at: http://www.gemini.edu/media/images_2003-2.html.

The remarkable detail in the Gemini images was made possible by Altair’s unique ability to correct starlight that has been blurred by atmospheric turbulence using adaptive optics with altitude conjugation.

Most adaptive optics systems that are currently in use correct for distortions to starlight by assuming that all of the distortions occur where starlight is collected – near the surface of the telescope’s primary mirror. In an altitude-conjugated system like Gemini’s, the distortions are assumed to be at the dominant turbulence layer of the atmosphere. By conjugating or tuning the system for a specific layer above the telescope, Altair can generate a more accurate model of the starlight’s path through our atmosphere.

“Adaptive optics with altitude conjugation is a pioneering new technique that is a powerful way to measure and fix distortions to starlight, which traveled undisturbed for vast distances through space until hitting pockets of warm and cold air in earth’s atmosphere,” said Glen Herriot, the systems engineer who managed the building of Altair in Victoria, BC at the laboratories of the National Research Council of Canada. Altair is able to precisely correct the distorted starlight up to 1,000 times per second using a sophisticated, deformable mirror about the size of the palm of your hand. “The end result is,” says Herriot, “images that rival or even exceed the sharpness of pictures taken from space.”

Working with Gemini Observatory personnel, the Canadian team headed by Project Manager Herriot and Project Scientist Dr. Jean-Pierre V?ran, have been commissioning Altair on Gemini North from late 2002 through early 2003. The instrument team, comprised of 25 scientists and engineers, guided the Gemini adaptive optics system from design to commissioning over the past six years. “Commissioning a precision instrument on a 7-story, 350-ton, sophisticated telescope is especially challenging because of the extremely intricate coordination required to make all the systems work together seamlessly,” said Herriot. Altair’s commissioning on Gemini is expected to be complete before the end of 2003.

A key feature of Altair’s sophistication is the ability to automatically monitor, adjust and optimize multiple parameters during image exposures. The idea is to make adaptive optics user-friendly for our community. When atmospheric conditions allow, simply point and click and near diffraction-limited images are delivered to a camera or spectrograph. Altair continually measures and reports on the images’ level of detail making it one of the most efficient adaptive optics systems in the world. “By routinely delivering infrared images much sharper than is currently possible even from space, Altair gives observers a tremendous advantage in probing deeper in the universe and making more accurate measurements of astronomical objects,” Dr. V?ran says.

“Altair enormously enhances the quality and power of our imaging and spectroscopy,” says Dr. Matt Mountain, Gemini’s Director. “Gemini will soon deliver diffraction-limited images in the near-infrared.” Gemini’s theoretical diffraction limit (maximum resolution) is about 40 milli-arcseconds in the near-infrared H-band (1.6 micrometers wavelength). At this point in commissioning, Altair can deliver 60-milli-arcsecond resolution in the H-band (60 milli-arcseconds is comparable to viewing one grain of sand from about 1.6 kilometers or 1 mile away).

Dr. Mountain pointed out that Altair’s commissioning means that one of the most sophisticated adaptive optics system in the world is now built-in to Gemini North as a facility instrument, and will soon be routinely available to all scientists throughout the Gemini partnership.

“This is a major achievement towards our Gemini goal of delivering space-quality images from an 8-meter, ground-based telescope,” said Dr. Mountain.

Gemini’s Associate Director Dr. Jean-Ren? Roy explains that Altair is a major step forward in Gemini’s aggressive plans to maximize the potential of adaptive optics on ground-based astronomical imaging. Dr. Roy elaborates, “Altair, representing the foundation of tomorrow’s adaptive optics technology, is important for the success of the next generation of 30- to 100-meter, diffraction-limited, infrared, ground-based telescopes now on the drawing boards.”

Future generations of adaptive optics technologies like these will undoubtedly revolutionize ground-based astronomy. For now, Altair is state of the art and provides a powerful new eye on the universe.

Original Source: Gemini News Release

Posted on by Fraser Cain

Mars Express is On Its Way

Image credit: ESA

After a picture perfect launch Monday afternoon, the European Space Agency’s Mars Express is now headed towards the Red Planet. The spacecraft, attached to the top of a 4-stage Russian Soyuz-Fregat rocket, lifted off from the Baikonur cosmodrome at 1745 GMT. Over the course of the next 90 minutes, the rocket shed each one of its four stages during an orbit around the Earth and then hurled the Mars Express into its planned trajectory. Mars Express communicated back with European Space Operations at 1944 GMT. The probe’s solar arrays had deployed properly, its batteries are working, and the spacecraft seems to be working normally. It will reach Mars in another six months.

The European Mars Express space probe has been placed successfully in a trajectory that will take it beyond the terrestrial environment and on the way to Mars ? getting there in late December.

This first European Space Agency probe to head for another planet will enter an orbit around Mars, from where it will perform detailed studies of the planet?s surface, its subsurface structures and its atmosphere. It will also deploy Beagle 2, a small autonomous station which will land on the planet, studying its surface and looking for possible signs of life, past or present.

The probe, weighing in at 1 120 kg, was built on ESA?s behalf by a European team led by Astrium. It set out on its journey to Mars aboard a Soyuz-Fregat launcher, under Starsem operational management. The launcher lifted off from Ba?konur in Kazakhstan on 2 June at 23.45 local time (17:45 GMT). An interim orbit around the Earth was reached following a first firing of the Fregat upper stage. One hour thirty-two minutes after lift off, the probe was injected into its interplanetary orbit.

“Europe is on its way to Mars to stake its claim in the most detailed and complete exploration ever done of the Red Planet. We can be very proud of this and of the speed with which have achieved this goal”, said David Southwood, ESA’s Director of Science witnessing the launch from Baikonur. Contact with Mars Express has been established by ESOC, ESA?s satellite control centre, located in Darmstadt, Germany.

The probe is pointing correctly towards the Sun and has deployed its solar panels. All on-board systems are operating faultlessly. Two days from now, the probe will perform a corrective man?uvre that will place it in a Mars-bound trajectory, while the Fregat stage, trailing behind, will vanish into space ? there will be no risk of it crashing into and contaminating the Red Planet.

Mars Express will then travel away from Earth at a speed exceeding 30 km/s (3 km/s in relation to the Earth), on a six-month and 400 million kilometre journey through the solar system. Once all payload operations have been checked out, the probe will be largely deactivated. During this period, the spacecraft will contact Earth only once a day. Mid-journey correction of its trajectory is scheduled for September.

There in time for Christmas
Following reactivation of its systems at the end of November, Mars Express will get ready to release Beagle 2. The 60 kg capsule containing the tiny lander does not incorporate its own propulsion and steering system and will be released into a collision trajectory with Mars, on 20 December. It will enter the Martian atmosphere on Christmas day, after five days? ballistic flight.

As it descends, the lander will be protected in the first instance by a heat-shield; two parachutes will then open to provide further deceleration. With its weight down to 30 kg at most, it will land in an equatorial region known as Isidis Planitia. Three airbags will soften the final impact. This crucial phase in the mission will last just ten minutes, from entry into the atmosphere to landing.

Meanwhile, the Mars Express probe proper will have performed a series of man?uvres through to a capture orbit. At this point its main motor will fire, providing the deceleration needed to acquire a highly elliptical transition orbit. Attaining the final operational orbit will call for four more firings. This 7.5 hour quasi-polar orbit will take the probe to within 250 km of the planet.

Getting to know Mars ? inside and out
Having landed on Mars, Beagle 2 ? named after HMS Beagle, on which Charles Darwin voyaged round the world, developing his evolutionary theory ? will deploy its solar panels and the payload adjustable workbench, a set of instruments (two cameras, a microscope and two spectrometers) mounted on the end of a robot arm.

It will proceed to explore its new environment, gathering geological and mineralogical data that should, for the first time, allow rock samples to be dated with absolute accuracy. Using a grinder and corer, and the ?mole?, a wire-guided mini-robot able to borrow its way under rocks and dig the ground to a depth of 2 m, samples will be collected and then examined in the GAP automated mini-laboratory, equipped with 12 furnaces and a mass spectrometer. The spectrometer will have the job of detecting possible signs of life and dating rock samples.

The Mars Express orbiter will carry out a detailed investigation of the planet, pointing its instruments at Mars for between half-an-hour and an hour per orbit and then, for the remainder of the time, at Earth to relay the information collected in this way and the data transmitted by Beagle 2.

The orbiter?s seven on-board instruments are expected to provide considerable information about the structure and evolution of Mars. A very high resolution stereo camera, the HRSC, will perform comprehensive mapping of the planet at 10 m resolution and will even be capable of photographing some areas to a precision of barely 2 m. The OMEGA spectrometer will draw up the first mineralogical map of the planet to 100 m precision.

Only a start to exploration
This mineralogical study will be taken further by the PFS spectrometer ? which will also chart the composition of the Martian atmosphere, a prerequisite for investigation of atmospheric dynamics. The MARSIS radar instrument, with its 40 m antenna, will sound the surface to a depth of 2 km, exploring its structure and above all searching for pockets of water.

Another instrument, ASPERA, will be tasked with investigating interaction between the upper atmosphere and the interplanetary medium. The focus here will be on determining how and at what rate the solar wind, in the absence of a magnetic field capable of deflecting it, scattered the bulk of the Martian atmosphere into space. Atmospheric investigation will also be performed by the SPICAM spectrometer and the MaRS experiment, with special emphasis on stellar occultation and radio signal propagation phenomena.

The orbiter mission should last at least one Martian year (687 days), while Beagle 2 is expected to operate on the planet?s surface for 180 days. This first European mission to Mars incorporates some of the objectives of the Euro-Russian Mars 96 mission, which came to grief when the Proton launcher failed. And indeed a Russian partner is cooperating on each of the orbiter?s instruments. Mars Express forms part of an international Mars exploration programme, featuring also the US probes Mars Surveyor and Mars Odyssey, the two Mars Exploration Rovers and the Japanese probe Nozomi. Mars Express may perhaps, within this partnership, relay data from the NASA rovers while Mars Odyssey may, if required, relay data from Beagle 2.

The mission?s scientific goals are of outstanding importance. Mars Express will, it is hoped, supply answers to the many questions raised by earlier missions ? questions concerning the planet?s evolution, the history of its internal activity, the presence of water below its surface, the possibility that Mars may at one time have been covered by oceans and thus have offered an environment conducive to the emergence of some form of life, and even the possibility that life may still be present, somewhere in putative subterranean aquifers. In addition the lander doing direct analysis of the soil and the environment comprises a truly unique mission.

Mars Express, drawing heavily on elements of the Rosetta spacecraft awaiting to be launched to a comet next year, paves the way for other ESA-led planetary missions, with Venus Express planned for 2005 and the BepiColombo mission to Mercury at the end of the decade. It is a precursor too for continuing Mars mission activity under Aurora, the programme of exploration of our solar system.

Original Source: ESA News Release

Posted on by Fraser Cain

Book Review – The Complete Book of Spaceflight

The Complete Book of Spaceflight ($24.50 US from Amazon.com) by David Darling is exactly that, an encyclopedia of space exploration, from Apollo to zero gravity. I have to be honest though; I didn’t read this book cover to cover. It’s got 3,000 detailed listings in alphabetical order, so it’s not exactly light reading material – imagine reading an encyclopedia. I have; however, been using it as a reference book for several months, and it’s in that capacity that it really shines.

Darling clearly had the non-technical reader in mind when he wrote up his descriptions, as he steers well clear of jargon (in a jargon-laden industry), and I appreciate that he kept some descriptions very short. For spaceflight terms the book functions as a dictionary, and the explanations are kept to a few sentences. For other topics, the book functions more like an encyclopedia; in some cases several pages are dedicated to a single topic (Gemini Program, spacesuits, etc).

If Darling were standing in front of me, and asked me? “well, what do you think? Is it complete?” I’d have to say yes. It’s complete. Everything that has anything to do with spaceflight is in there. I’ve found it useful to consult entries before writing up some of my own stories in Universe Today; especially if it’s been several years since I last wrote about a subject (although some space agencies have great press material, many of the aerospace firms provide descriptions of their own programs drenched in marketing-speak).

Taking its cue from its encyclopedic parent, The Complete Book of Spaceflight is liberally sprinkled with photographs, sidebars and tables of information. Unfortunately, the pages are all black-and-white, so you don’t get to see any of the images in colour. I wish the publisher could have splurged on full-colour printing – this would let the book spend equal time on your desk and coffee table (maybe they’ll consider it for a future edition?).

The other problem, and this is no fault of the author, is that the business of space exploration is still unfolding. Events in the last few months would have already rewritten chunks of the book (Columbia, Rosetta), so it would be cool to see some kind of Internet site with updates.

I think you’d be happy to have The Complete Book of Spaceflight sitting on your desk or in your bookshelf, standing by to help you navigate some of the more obscure space news journals, like, uh? Universe Today.

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Closest Gamma Ray Burst Ever Discovered

Image credit: NRAO

Gamma ray bursts (GRB) are the largest known explosions in the Universe; immensely powerful, quick to fade, but usually incredibly far away. Astronomers with the National Radio Astronomy Observatory got lucky, though, when they analyzed a recent GRB and discovered it was only 2.6 billion light-years away (most are usually 4 times more distant). What causes these bursts is a mystery, but the theories usually incorporate black holes in some catastrophic way – colliding into another black hole; wrapping a magnetic field like a spring, etc. This close burst didn’t answer the mystery, but it did allow the astronomers to rule out one idea, that material from a GRB blasts out like “cannonballs”.

The closest Gamma Ray Burst (GRB) yet known is providing astronomers with a rare opportunity to gain information vital to understanding these powerful cosmic explosions. Extremely precise radio-telescope observations already have ruled out one proposed mechanism for the bursts.

“This is the closest and brightest GRB we’ve ever seen, and we can use it to decipher the physics of how these bursts work,” said Greg Taylor of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Taylor worked with Dale Frail, also of the NRAO, along with Prof. Shri Kulkarni and graduate student Edo Berger of Caltech in studying a GRB detected on March 29, 2003. The scientists presented their findings to the American Astronomical Society’s meeting in Nashville, TN.

VLBA IMAGE of GRB 030329

CREDIT: NRAO/AUI/NSF
(Click on Image for Larger Version)

Taylor and Frail used the National Science Foundation’s (NSF) Very Long Baseline Array (VLBA) and other radio telescopes to study the burst, known as GRB 030329. In a series of observations from April 1 to May 19, they determined the size of the expanding “fireball” from the burst and measured its position in the sky with great precision.

At a distance of about 2.6 billion light-years, GRB 030329 is hardly next door. However, compared to other GRBs at typical distances of 8-10 billion light-years, it presents an easier target for study.

“We only expect to see one burst per decade this close,” said Frail.

The precise measurement of the object’s position allowed the scientists to show that one theoretical model for GRBs can be ruled out. This model, proposed in 2000, says that the radio-wave energy emitted by the GRB comes from “cannonballs” of material shot from the explosion at extremely high speeds.

“The ‘cannonball model’ predicted that we should see the radio-emitting object move across the sky by a specific amount. We have not seen that motion,” Taylor said.

The currently standard “fireball model” of GRBs says that the radio emission comes from a rapidly-expanding shock wave. This model was first proposed by Peter Meszaros, Bohdan Paczynski and Sir Martin Rees, who won the American Astronomical Society’s Bruno Rossi Prize in 2000 for their work. In this standard model, as the shock wave expands outward, the emission becomes fainter, but the center of the observed emission does not change position.

The cannonball model, however, proposes that the emission arises from distinct concentrations of matter shot outward from the burst. As they move farther from the burst, their motion should be detected as a change in their position in the sky. On April 3, proponents of the cannonball model predicted a specific amount of motion for GRB 030329 and suggested that the VLBA’s sharp radio “vision” could detect the motion and confirm their prediction.

Instead, “our observations are consistent with no motion at all,” Taylor said. “This is at odds with the cannonball model — they made a specific prediction based on their model and the observations do not bear them out,” he added.

The scientists’ direct measurement of the size of the GRB fireball also will provide new insights into the physics behind the burst.

“By directly measuring the size and the expansion rate, we can start putting some real limits on the physics involved,” Taylor said. First, he said, “We already can confirm that the fireball is expanding at nearly the speed of light, as the standard model predicts. Next, once our May observations are fully analyzed, we can put limits on the energy of the burst and provide a test of the standard model.”

Taylor and Frail observed GRB 030329 with the VLBA on April 1 and April 6. On April 22, they used the 100-meter radio telescope in Effelsberg, Germany in addition to the VLBA. On May 19, they used the VLBA, the Very Large Array (VLA) in New Mexico, the NSF’s Robert C. Byrd Green Bank Telescope in West Virginia, and the Effelsberg telescope.

In addition to gamma-ray and X-ray observations, visible light from GRB 030329 was observed by 65 telescopes around the world. At its brightest, the visible light from this burst was detectable with moderate-sized amateur telescopes.

Gamma Ray Bursts were first detected in 1967 by a satellite monitoring compliance with the 1963 atmospheric nuclear test-ban treaty. For three decades thereafter, astronomers were unable to determine their distances from Earth, and thus were unable to begin understanding the physics underlying the explosions. In 1997, the first distance measurements were made to GRBs, and the NSF’s Very Large Array (VLA) detected the first radio emission from a GRB afterglow.

Once scientists determined that GRBs originate in distant galaxies and that they probably occur in regions of those galaxies where stars are actively forming, some 200 proposed models for what causes GRBs were reduced to a handful of viable models.

Most scientists now believe that GRBs arise from a violent explosion that ends the life of a star much more massive than the Sun. Whereas such an explosion as a typical supernova leaves a dense neutron star, a GRB explosion leaves a black hole, a concentration of mass with gravitational pull so strong that not even light can escape it.

The VLBA is a continent-wide system of ten radio- telescope antennas, ranging from Hawaii in the west to the U.S. Virgin Islands in the east, providing the greatest resolving power, or ability to see fine detail, in astronomy. Dedicated in 1993, the VLBA is operated from the NRAO’s Array Operations Center in Socorro, New Mexico.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Original Source: NRAO News Release

Posted on by Fraser Cain

Mars Express is Ready For Launch

Image credit: ESA

Europe is ready to begin this summer’s invasion of Mars with the launch of its Mars Express spacecraft, due to lift off on June 2. The spacecraft is currently packed safely away on top a Soyuz-Fregat rocket at the Baikonur cosmodrome in Kazakhstan. If all goes well, the rocket will lift off at 1745 GMT and then deploy Mars Express 90 minutes later. The first critical hurdle for the mission will be three days after launch when the spacecraft needs to release the launch clamps holding the Beagle-2 lander so that it can be deployed in December when they reach Mars.

ESA?s Mars Express is a pioneering mission for several reasons. It is the first European voyage to Mars, it has been built at much less than the usual cost, and in record time.

Mars Express is the first example of ESA?s new style of developing scientific missions: faster, smarter and more cost-effective, but without compromising reliability and quality – there have been no cuts in tests or pre-launch preparations. Mars Express will face demanding technical challenges during its trip to the Red Planet and ESA engineers have worked hard to make sure it meets them.

“With Mars Express, Europe is building its own expertise in many fields. This ranges from the development of science experiments and new technologies – new for European industry – to the control of a mission that includes landing on another planet. We have never done this before,? says Rudi Schmidt, Mars Express Project Manager.

Quicker, smarter?safe!
Mars Express?s design and development phase has taken about four years, compared with about six years for previous similar missions. And its cost, 300 million euros, is much less than other comparable planetary missions. The ?magic? lies in the new managerial approach being used.

This new approach includes the reuse of existing hardware and instruments. Also, the mission was developed by a smaller ESA team, who gave more responsibility to industry. Mars Express has been built by a consortium of 24 companies from ESA?s 15 Member States and the United States, led by Astrium as prime contractor.

However, mission safety was never compromised. ?Although we were under heavy pressure towards the end of the project, we did not drop any of the planned tests to save time. I call this a fast design phase, followed by thorough testing activity,? says Schmidt.

This new streamlined development method will continue with Venus Express and probably other future missions.

Launch
Mars Express will be launched on 2 June on board a Soyuz-Fregat rocket from the Baikonur Cosmodrome in Kazakhstan. The mission consists of an orbiter and a lander, called Beagle 2. In its launch configuration, Mars Express is a honeycombed aluminium box that measures 1.5 by 1.8 by 1.4 metres (excluding solar panels), and weighs 1223 kilograms in total. The Beagle-2 lander travels attached to one side of the spacecraft, folded up rather like a very large pocket watch. Arrival at Mars is scheduled for late December this year, when Beagle 2 will land while the orbiter is entering its orbit around Mars.

The last activities of an intense launch campaign are taking place in Baikonur at this very moment. Mars Express arrived at the Cosmodrome on 20 March. The spacecraft, fuelled with 457 kilograms of propellant, was mounted on the Soyuz launcher on 24 May in a process that the Russians call ?marriage?. The whole structure was rolled out to the launch pad on 29 May, four days before launch.

The fastest possible trip to Mars
One of the reasons scientists had to develop Mars Express so quickly arises from the fact that, this summer, Mars and the Earth will be especially close to each other. Although launch opportunities to go to Mars occur every 26 months – when the Sun, Earth and Mars form a straight line – this year the planets will be at their closest, which happens every 15 to 17 years. On top of that, calculations had shown that the best combination of fuel expenditure and travel time could only be achieved by launching in the period between 23 May and 21 June. The Mars Express team had to work very hard to meet this launch window.

As a tribute from one European high-tech organisation to another, Mars Express is carrying a small container of Ferrari red paint to the Red Planet.

After the launch
Mars Express will separate from the Soyuz Fregat upper stage 90 minutes after liftoff. Then the solar arrays will open and the spacecraft will make contact with ESA?s ground station in New Norcia, Western Australia.

Mars Express will be travelling away from Earth at a speed of 3 kilometres per second. A crucial operation at this early stage of the trip will be to release the Beagle-2 launch clamps three days after launch. These clamps are extra gears to make sure that the lander stays securely attached to the spacecraft during the launch, but once in space they are not needed any more. A pyrotechnic device will be activated to release them. This will be a key step, necessary so that Beagle 2 can be ejected when the spacecraft arrives at Mars.

Every effort has been made to ensure that things go smoothly. Schmidt says: ?We have tested all aspects of the mission well enough to be confident that there will be no errors or trivial mistakes. Mars Express has been developed in record time, but there have been no compromises on testing, including the ground segment.”

Orbiting and landing on Mars
Six days before arrival at Mars, the lander will be released. This operation is regarded as one of the most complex of the Mars Express mission. Beagle 2, which weighs only 65 kilograms, is too light to carry a steering mechanism and is not designed to receive commands during cruise and landing. So Beagle 2 can only reach its planned landing site by relying on the orbiter to put it into the correct trajectory and drop it at a very precise point in space and at a specified speed. The ground control team at the European Space Operations Centre (ESOC) in Darmstadt, Germany, will guide this manoeuvre. To be ready for the approach to Mars and the ejection operations, engineers have been training for months with simulators that resemble sophisticated computer games. Tests will continue after Mars Express?s launch.

Mars Express will study Mars for at least two years
Approaching Mars, the orbiter will eject the lander and then be left on a collision course with the planet. In another key manoeuvre, ground controllers will have to adjust its trajectory, reducing its speed to 1.8 kilometres per second. At that speed, the planet?s gravity will be able to ?capture? the Mars Express orbiter and put it into Mars orbit. Ground controllers will still have to perform several manoeuvres to get the spacecraft into its final operational state – a highly elliptical polar orbit – from where the scientific observations can begin.

In the meantime, Beagle 2 will have landed on Mars. The landing area covers a large ellipsis, 300 kilometres long and 150 kilometres wide, on an equatorial region called Isidis Planitia. It was chosen in the light of the strong Martian winds and the relatively smooth surface of the site. The lander will deploy parachutes, and then large gas-filled bags will protect it as it bounces to a halt on the surface. Once landed, Beagle 2 will emit a ?beep?, a signal that will tell operators at the United Kingdom?s Jodrell Bank radio telescope station that it has touched down safely. This 9-note call sign was composed for the Beagle-2 team by the British pop group, Blur.

Mars Express will investigate the Martian surface, subsurface, and atmosphere for at least two years. The lander will operate on the surface for about six Earth months, relaying its data to Earth through the orbiter.

Mars Express will help answer fundamental questions about Mars, such as the presence and quantity of water, and possible signs of present or past life. In the worldwide effort to explore the Red Planet in recent years, the European Mars Express mission represents the most thorough investigation of Mars attempted so far.

Original Source: ESA News Release

Posted on by Fraser Cain

Northern Europe Treated to Eclipse Show

Skywatchers in Northern Europe were treated to a show on Saturday, May 31 when the Moon passed in front of the Sun and created an annular eclipse. Astrocameras at the Copernicus Public Observatory in the Netherlands and the Mira Public Observatory in Belgium caught the whole event live, and dozens of amateur astronomers across Europe have submitted their own photos as well. The next solar eclipse will be on November 23, but will only be visible from Antarctica.