Posted on by Fraser Cain

Toutatis Safely Passes the Earth

Today, September 29, 2004, is undisputedly the Day of Toutatis, the famous “doomsday” asteroid.

Not since the year 1353 did this impressive “space rock” pass so close by the Earth as it does today. Visible as a fast-moving faint point of light in the southern skies, it approaches the Earth to within 1,550,000 km, or just four times the distance of the Moon.

Closely watched by astronomers since its discovery in January 1989, this asteroid has been found to move in an orbit that brings it close to the Earth at regular intervals, about once every four years. This happened in 1992, 1996, 2000 and now again in 2004.

Radar observations during these passages have shown that Toutatis has an elongated shape, measuring about 4.6 x 2.4 x 1.9 km. It tumbles slowly through space, with a rotation period of 5.4 days.

The above images of Toutatis were taken with the ESO Very Large Telescope (during a technical test) in the evening of September 28. They were obtained just over 12 hours before the closest approach that happens today at about 15:40 hrs Central European Summer Time (CEST), or 13:40 hrs Universal Time (UT). At the time of these observations, Toutatis was about 1,640,000 km from the Earth, moving with a speed of about 11 km/sec relative to our planet.

They show the asteroid as a fast-moving object of magnitude 10, about 40 times fainter than what can be perceived with the unaided, dark-adapted eye. They also prove that Toutatis is right on track, following exactly the predicted trajectory in space and passing the Earth at a safe distance, as foreseen.

Detailed calculations, taking into account all available observations of this celestial body, have shown that although Toutatis passes regularly near the Earth, today’s passage is the closest one for quite some time, at least until the year 2562. The ESO observations, obtained at a moment when Toutatis was very close to the Earth, will help to further refine the orbital calculations.

The “parallax effect” demonstrated!
Simultaneous images obtained with telescopes at ESO’s two observatories at La Silla and Paranal demonstrate the closeness of Toutatis to the Earth. As can be seen on the unique ESO PR Photo 28e/04 that combines two of the exposures from the two observatories, the sighting angle to Toutatis from the two observatories, 513 km km apart, is quite different. Astronomers refer to this effect as the “parallax”. The closer the object is, the larger is the effect, i.e., the larger will be the shift of the line-of-sight.

Interestingly, the measured angular distance in the sky of the beginnings (or the ends) of the two trails (about 40 arcsec), together with the known distance between the two observatories and the position of Toutatis in the sky at the moment of the exposures fully define the triangle “Paranal-Toutatis-La Silla” and thus allow to calculate the exact distance to the asteroid.

It is found to be very close to that predicted from the asteroid’s position in its orbit and that of the Earth at the moment of this unique observation, 1,607,900 km. This exceptional, simultaneous set of observations thus provides an independent measurement of Toutatis’ distance in space and, like the measured positions, a confirmation of its computed orbit.

More information about Toutatis is available at the dedicated webpage by the French discoverers and also at the specialised Near-Earth Objects – Dynamic Site.

Original Source: ESO News Release

Posted on by Fraser Cain

Halfway There: SpaceShipOne Hits Space Again

Image credit: Scaled Composites
There was a short delay and then SpaceShipOne took off at 1411 UTC (7:11am PDT) cradled under the White Knight carrier aircraft. It carried SpaceShipOne to an altitude of nearly 14 km (46,000 ft) and then released it.

Pilot Mike Melvill ignited the rocket, pointed the spacecraft directly up and accelerated to Mach 3, reaching the edge of space just a few minutes later – 100 km (62.5 miles).

The flight didn’t go as smoothly as designer Burt Rutan had predicted, however. Shortly after igniting its hybrid rocket engine and heading up into space, SpaceShipOne went into a harrowing corkscrew roll, spinning more than 20 barrel rolls. Melvill cut the spacecraft’s engine 11 seconds before it would have turned off automatically and was able to get control again. Melvill noted, “we would have gone much higher.”

In order to win the $10 million X-Prize, competitors need to complete the trip to space twice in two weeks carrying the pilot and the weight of two passengers. Instead of carrying dead weight, SpaceShipOne was filled with personal objects from the employees of the companies that built it.

Their next flight is expected to happen on October 4 – the 47th anniversary of the launch of Sputnik.

After the flight, Burt Rutan presented financier Paul Allen with tiny pine trees that had been carried into space. Rutan’s company has invested more than $20 million into SpaceShipOne, and recently inked a deal with Sir Richard Branson’s Virgin Galactic to develop a larger version of the prototype that could carry 5 paying passengers into space; it could start flying within a few years.

Written by Fraser Cain

Posted on by Fraser Cain

Eat Like a Martian in Alaska

Image credit: ISECCo
Ray and some friends built Mars Base Zero a few years ago on a borrowed plot of land just outside Fairbanks, Alaska. It’s a fairly normal looking greenhouse 11 metres (36 feet) long, and two-thirds as wide. One half of the cylindrical roof is clear plastic, and the other half is well insulated. There’s also a small apartment attached to one end for Ray to live in while he tends to his Martian garden.

Inside you’ll find a healthy crop of potatoes, carrots, cabbage, tomatoes, and plenty of other produce to make a vegan smile – mostly, though, you’ll find potatoes. Through several years of experimentation, Ray has learned that a single human requires about 80 square metres (864 square feet) of soil to grow enough food to survive.

Assuming you’re willing to eat a lot of potatoes.

“We tried growing wheat, but we could have gotten several pounds of potatoes for an area that gave me just a cupful of wheat. I’m guessing that 4-5 chickens would eat the same amount as me. We might try fish, though.”

Collins is one of the original co-founders of the International Space Exploration and Colonization Co. (ISECCo); a non-profit organization hoping to contribute knowledge to the human exploration of space. Instead of building rockets in their garages, the ISECCo team decided to do something much lower budget: Closed Ecological Life Support System Research. Sort of like Biosphere II, but without all the fancy ecosystems… and drama.

They started in 1988, and built a series of experiments leading up to Mars Base Zero – a $30,000 investment. Maintaining the experiment has only cost $900 this year, since they planted the crops in May 2004. Ray figures he’s put $40,000 of his own money into the various experiments since 1988.

The only purpose of Mars Base Zero is to understand how much space is required, and which crops to grow to keep an astronaut well fed. If you could seal it up tight, and ship it to Mars, Ray figures that it would get enough sunlight on Mars to have the plants nearly growing as well as they do in Alaska.

Ray began this experiment on September 17, and he’s been keeping a detailed log of the food he’s been eating – the potatoes he’s been eating – and the, um, “waste” he’s been generating. He hasn’t lost any weight so far, but he has to eat several kilograms of food every day just to maintain. A nutritionist probably wouldn’t be too pleased with his diet so far, but Ray’s aware of the inadequacies and has new crops planned for next time around. If everything goes well, he’ll stay in for at least 30 days, and maybe as long as 60 days if the potatoes hold out. His wife is expecting to deliver their second child in December, so Ray’s got a hard deadline anyway.

Normally they plant in the spring, and then harvest in the fall. But Ray would like to try planting continuously, and keep it going as long into the winter as he can afford to pay for lights and heat. Eventually he hopes they’ll get to the point that it’s a year round operation.

And then they’ll take the experiment to the next level… underground.

ISECCo plans to build an underground dome, called Nauvik (Eskimo term for “nurturing place”), twice the same area as the greenhouse, but seal it completely off from the Earth’s environment. Water, air and other nutrients would be carefully monitored, and the plants would be grown by powerful lamps – the electricity bill alone will probably run $5,000 a month. The advantage is that they could simulate a lunar or Martian environment; even experimenting with different air pressures to see how the plants react. With the heat from the lamps, Ray expects one of the most difficult challenges will be keeping it cool.

It’ll be an expensive proposition. Especially without government or NASA funding. “We responded to a NASA request-for-proposal that was looking for unique ideas in closed system life support.” Ironically, the agency complained that their idea was “too unique”.

Maybe the astronauts weren’t willing to eat that many potatoes.

Written by Fraser Cain

Posted on by Fraser Cain

Mars Rover Tracks Spotted From Space

NASA’s Mars Global Surveyor, starting its third mission extension this week after seven years of orbiting Mars, is using an innovative technique to capture pictures even sharper than most of the more than 170,000 it has already produced.

One dramatic example from the spacecraft’s Mars Orbiter Camera shows wheel tracks of NASA’s Mars Exploration Rover Spirit and the rover itself. Another tells scientists that no boulders bigger than about 1 to 2 meters (3 to 7 feet) are exposed in giant ripples created by a catastrophic flood.

Those examples are available online at http://www.msss.com/mars_images/moc/2004/09/27/ and http://mars.jpl.nasa.gov/mgs. In addition, about 24,000 newly catalogued images that Mars Global Surveyor took between October 2003 and March 2004 have been added to the Mars Orbiter Camera Image Gallery at http://www.msss.com/moc_gallery/. These include additional pictures of the Mars Exploration Rover sites seen from orbit.

“Over the past year and a half, the camera and spacecraft teams for Mars Global Surveyor have worked together to develop a technique that allows us to roll the entire spacecraft so that the camera can be scanned in a way that sees details at three times higher resolution than we normally get,” said Dr. Ken Edgett, staff scientist for Malin Space Science Systems, San Diego, Calif., which built and operates the Mars Orbiter Camera. The technique adjusts the rotation rate of the spacecraft to match the ground speed under the camera.

“The image motion compensation is tricky and the spacecraft does not always hit its target. However, when it does, the results can be spectacular,” Edgett said.

The Mars Orbiter Camera acquires the highest resolution images ever obtained from a Mars-orbiting spacecraft. During normal operating conditions, the smallest objects that can be resolved on the martian surface in these images are about 4 to 5 meters (13 to 16 feet) across. With the adjusted-rotation technique, called “compensated pitch and roll targeted observation,” objects as small as 1.5 meters (4.9 feet) can be seen in images from the same camera. Resolution capability of 1.4 meters (4.6 feet) per pixel is improved to one-half meter (1.6 feet) per pixel. Because the maneuvers are complex and the amount of data that can be acquired is limited, most images from the camera are still taken without using that technique.

Mars Global Surveyor began orbiting Mars on Sept. 12, 1997. After gradually adjusting the shape of its orbit, it began systematically mapping the planet in March 1999. The Mars Orbiter Camera’s narrow-angle camera has now examined nearly 4.5 percent of Mars’ surface, including extensive imaging of candidate and selected landing sites for surface missions. The Mars Orbiter Camera also includes a wide-angle camera that observes the entire planet daily.

“Mars Global Surveyor has been productive longer than any other spacecraft ever sent to Mars, since it surpassed Viking Lander 1’s longevity earlier this year and has returned more images than all past Mars missions combined,” said Tom Thorpe, project manager for Mars Global Surveyor at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. The mission will complete its 25,000th mapping orbit on Oct. 11.

Principal goals for the orbiter’s latest mission extension, beginning Oct. 1, include continued weather monitoring to form a continuous set of observations with NASA’s next Mars mission, Mars Reconnaissance Orbiter, scheduled to reach the red planet in 2006; imaging of possible landing sites for the Phoenix 2007 Mars Scout lander and 2009 Mars Science Laboratory rover; continued mapping and analysis of key sedimentary-rock outcrop sites; and continued monitoring of changes on the surface due to wind and ice. Because the narrow-angle camera has imaged only a small fraction of the surface, new discoveries about surface features are likely to come at any time. The extension runs two years, through September 2006, with a budget of $7.5 million per year.

Dr. James Garvin, NASA’s chief scientist for Mars and the Moon, said, “Mars Global Surveyor continues to catalyze new science as it explores Mars at scales compatible with those that our Mars Exploration Rovers negotiate every day, and its extended mission will continue to set the stage for upcoming observations by the Mars Reconnaissance Orbiter.”

Additional information about Mars Global Surveyor is available online at: http://mars.jpl.nasa.gov/mgs/. In addition to semi-annual releases of large collections of archived pictures, the Mars Orbiter Camera team posts a new image daily and last year began soliciting public suggestions for camera targets on Mars. These materials can be viewed online at http://www.msss.com . For more information about NASA and other space science programs on the Internet, visit http://www.nasa.gov.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Global Surveyor mission for NASA’s Science Mission Directorate, Washington, D.C. JPL’s industrial partner is Lockheed Martin Space Systems, Denver, which built and operates the spacecraft.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Here Come The Thirty Metre Telescopes

Thirty Metre Optical and Infrared ground-based telescopes should be seeing first light in about 2011, and be fully operational by 2015. Four such instruments are in the works, CalTech?s TMT, Gemini?s GSMT, Canada?s VLOT, and Europe?s ELT. With 100 times the speed of Hubble, and three times the resolution of the Keck instruments, these tools will help unlock some new keys to our understanding the cosmos.

Earth-based thirty-metre telescopes are being funded, and designed now. Caltech’s TMT project will undergo design reviews in 2006 and 2007 with full construction funding scheduled to be given by the Gordon and Betty Moore Foundation in July 2008. Gordon Moore [of Moore?s Law fame] was the founder of Intel. His foundation supplied a 17 million dollar grant to design the TMT in October 2003. In total the instrument is expected to cost about 800 million dollars.

Adaptive optics have proved a tremendous success, and are one reason that there will be no replacement for the Hubble telescope as a space based tool for covering the optical and near infrared part of the spectrum. These three instruments will be getting first light with some segments about the same time that the 6.5 metre James Webb Space Telescope will begin its science mission in 2011-2.

Robert Gilmozzi?s OverWhelmingly Large Telescope [OWL project] is also trying to get first light by 2015, but faces more financial and technical obstacles than the 30-meter instruments. If the OWL doesn?t get built in this go-around, similar designs will likely be used for the following decade.

These instruments will be able to perform many tasks that the current generation of instruments either can?t do, or would require prohibitive amounts of observing time to accomplish including the following:

  • Map the density and heavy element content of the intergalactic media from nearby to beyond z=1.5 by measuring the details absorption spectra of 100,000 QSOs.
  • Observe the galaxy formation process by studying the movement of ionized gas clouds from z=3 to 8. Note these instruments can discern sources as close as 150 parsecs apart at z=3.
  • Chart the distortion of images of background galaxies when looking through galactic clusters to map the presence of dark matter to an unprecedented level of detail.
  • Chart the star populations of nearby galaxies observing element abundances, and determining formation histories.
  • Observe planet formation around the nearest thousand new stars. This instrument will be able to resolve to 0.4AU when looking at objects 33 light-years away.
  • Detect and characterize mature planets around nearby stars.

Caltech just put up a job posting for an Observatory Scientist for the TMT project. The Thirty metre telescopes are on their way.

Written by John A. Cross

Posted on by Fraser Cain

Toutatis Sneaks Past the Earth on Wednesday

Early Wednesday morning, a 5,500 million pound asteroid measuring 5 kilometers in length will pass very close to Earth.

An asteroid two to three times that diameter is credited with causing the extinction of 85 percent of the world’s species, including the dinosaurs, when it hit our planet 65 million years ago.

Luckily for us, asteroid Toutatis is only a tourist, and doesn’t plan to stop here. It will come within 1.5 million kilometers (960,000 miles) of Earth, or four times the Earth-moon distance. Toutatis is the largest asteroid to come that close in more than a century.

Many smaller asteroids often pass well inside the moon’s orbit. The Earth is also hit continually with tiny meteors that often become “shooting stars” as they harmlessly burn up in the atmosphere.

But if a rock the size of Toutatis hit, the atmosphere would do little more than slow it down a bit before it slammed to Earth. The impact would create a vast crater, and toss so much dust and vaporized minerals into the air the skies would darken. Seismic waves created by the explosion would generate tsunamis and earthquakes, and red-hot rocks falling back to Earth would ignite forest fires.

Toutatis, also known as asteroid 4179, is 4.6 kilometers (2.9 miles) long and 2.4 kilometers (1.5 miles) wide. Although Toutatis looks like a large peanut, radar images revealed it is actually composed of two rocks that are in close contact. One of the rocks is approximately twice as large as the other.

Toutatis has a strange rotation –instead of the spinning on a single axis, like the planets and most other asteroids do, Toutatis tumbles so erratically that its orientation with respect to the solar system never repeats.

“The vast majority of asteroids, and all the planets, spin about a single axis, like a football thrown in a perfect spiral,” says Scott Hudson of Washington State University, “but Toutatis tumbles like a flubbed pass.”

Toutatis’s four-year orbit around the sun is also eccentric, extending from just inside the Earth’s orbit to the main asteroid belt between Mars and Jupiter.

Astronomer Christian Pollas discovered Toutatis on January 4, 1989. Pollas spotted the asteroid on photographic plates taken by Alain Maury and Derral Mulholland, who had taken the photos while observing Jupiter’s satellites.

Toutatis flew close by Earth in 1992 and 1996, but it hasn’t come this near to us since 1353. The next time it will pass this close again will be in the year 2562. The asteroid’s orbit around the sun is so eccentric that it can’t be predicted with much certainty for more than a few hundred years in the future. Since researchers can’t say Toutatis will never hit Earth, it is currently listed as a Potentially Hazardous Asteroid.

There is a rumor circulating on the Internet that the asteroid will strike Earth during this 2004 flyby. However, astronomers have been tracking the path of Toutatis ever since it was discovered, and they are certain it will pass safely by Earth.

Throughout history, several asteroids have hit Earth. The solar system was cluttered with asteroids while the Earth was young, and the face of the moon and other dead planetary bodies shows how frequent such impacts were. Impacts by large rocks are much less frequent today, but they can still occur.

There are thought to be more than 300,000 nearby small asteroids (asteroids about 100 meters across). Such asteroids should statistically hit Earth once every few thousand years. The most recent such asteroid strike occurred in 1908, when an asteroid measuring about 60 meters in diameter hit Russia. The “Tunguska” bolide exploded in the atmosphere and flattened about 700 square miles of Siberian forest.

Large (1 kilometer or greater) asteroids are far more rare and infrequent. There are only about 1,100 nearby large asteroids, and they are predicted to strike the Earth every half million years or so. But when these asteroids strike, they can cause catastrophic changes in the global climate. Asteroids that cause mass extinctions are thought to be 10 kilometers or greater in diameter.

The Spaceguard Survey was established to track large asteroids and comets that might pose a direct threat to Earth. So far, the Spaceguard Survey has found about half of these NEOs, and they expect to find the majority of them by 2008.

Although Toutatis will be in the far southern sky when it is closest to Earth, the asteroid is expected to brighten a few days prior to a 10th magnitude point of light visible from the Northern Hemisphere. Sky-watchers should look for it near the bright star Delta Capricorni.

Toutatis won’t be visible to the naked eye, but binoculars should suffice for spotting it in the night sky. A telescope would provide the best viewing, because it would allow the viewer to detect the slow motion of Toutatis against the background stars.

Original Source: Astrobiology Magazine Article

Posted on by Fraser Cain

How Mars Could Be Losing Its Water

Image credit: ESA
Recent results from the ASPERA-3 instrument on board Mars Express confirm that a very efficient process is at work in the Martian atmosphere which could explain the loss of water. Water is believed to have once been abundant on the Red Planet. Professor Rickard Lundin, leader of the ASPERA-3 team, describes these findings in a paper published in the latest issue of ?Science?.

Mars is bombarded by a flood of charged particles from the Sun, commonly called the ?solar wind? and consisting of electrons and alpha particles. The solar wind erodes the atmosphere of Mars, and is believed to have stripped away a large amount of water that was present on the planet about 3.8 billion years ago. Geological evidence, as recently confirmed by images from the High Resolution Stereo Camera (HRSC) onboard Mars Express, indicates that water flows and even an ocean in the Northern hemisphere shaped the surface of Mars.

Today, water still exists on the Red Planet, but less than in the past. Observations made earlier this year by the OMEGA instrument on Mars Express showed that Mars has vast fields of perennial water ice, stretching out from its south pole.

The ASPERA-3 instrument on board Mars Express aims to answer the question of whether the solar wind interaction with the upper atmosphere of Mars contributes to the depletion of water. It is measuring a process called ?solar wind scavenging?, or the slow ?invisible? escape of volatile gases and liquid compounds which make up the atmosphere and hydrosphere of a planet. Using plasma spectrometers and a special imager to detect energetic neutral atoms, ASPERA-3 is making global and simultaneous measurements of the solar wind, the inflow of energetic particles, and also the ?planetary wind?, which is the outflow of particles from the Martian atmosphere and ionosphere.

Aspera 3 has established that the solar wind penetrates through the ionosphere and very deeply into the Martian atmosphere down to an altitude of 270 kilometres. This seems to be the reason for the acceleration processes that cause the loss of atmosphere on Mars.

Original Source: ESA News Release

Posted on by Fraser Cain

Da Vinci Project Pushes Back Launch

The Golden Palace.com Space Program Powered by the da Vinci Project announced that it has revised its October 2nd planned flight to space in pursuit of the Ansari X PRIZE.

Contributing factors to this revision were availability of a few key components and their integration into the overall space flight program. The Project will provide public notice of its intended flights as soon as practicable under the auspices of the Ansari X PRIZE, notwithstanding the flight plans of any other competitor.

?The flight insurance for the 2 launches has been secured?, says Brian Feeney, Project Leader. ?We?re still a go for launch. We?ve made milestone progress since the early August arrival of our title sponsor, Golden Palace.com and we intend to prove that Canadians can and will put a man into space?.

About The Golden Palace.com Space Program Powered by the da Vinci Project (www.davinciproject.com)
The Golden Palace.com Space Program Powered by the da Vinci Project’s aim of capturing the Ansari X PRIZE, the international “New Race to Space(R)” is backed by a core of volunteers from many walks of life and disciplines. Aerospace engineers, experts in project management and finance contribute their time and expertise towards the realization of the next step in Human discovery. The Project’s novel rocket design will be launched from the world’s largest reusable helium balloon at an altitude of 80,000 feet (24,400 meters). To learn more, visit www.davinciproject.com.

About the ANSARI X PRIZE Competition
In order to win the ANSARI X PRIZE, teams must build a safe/reusable space vehicle able to carry one pilot and the weight equivalent of two passengers 100km (62 miles) into sub-orbital space. The vehicle must be privately financed and safely launched twice within a two-week period. The first registered ANSARI X PRIZE team to complete this feat will win the $10 million prize and spectacular trophy.

About the X PRIZE Foundation (www.xprize.org)
The X PRIZE Foundation is a not-for-profit educational organization, with headquarters in St. Louis, Missouri. The Foundation?s ANSARI X PRIZE Competition is supported by its Title Sponsor the Ansari family and its Presenting Sponsor Champ Car World Series. The Foundation is also supported by private donations from the St. Louis Community through the New Spirit of St. Louis Organization. The Foundation’s mission is to educate the public about space travel, create educational programming for students and space enthusiasts, and provide incentives in the private sector to make space travel frequent and affordable for the general public. Several additional sponsorships for the ANSARI X PRIZE competition remain available to corporations or individuals who wish to support the contest and associate themselves with courage, determination, achievement, space, speed, high performance and technology.

Original Source: da Vinci Project News Release

Posted on by Fraser Cain

First Genesis Samples Shipped Out

The Genesis team has shipped its first scientific sample from the mission’s specially constructed cleanroom at the U.S. Army Proving Ground in Dugway, Utah. The sample, containing what are known as “lid foils,” was attached to the interior lid of the Genesis sample return capsule.

“This is the first batch in what we are growing more confident will be many more scientifically valuable samples,” said Genesis Project Manager Don Sweetnam of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “It appears that we have recovered about 75 to 80 percent of these lid foils. A great deal of credit has to go to the dedicated men and women of Genesis who continue to do very precise, detailed work out there in the Utah desert.”

After the sample was shipped from Utah, it was received by Genesis co-investigator Nishiizumi Kunihiko from the University of California, Berkeley, Space Sciences Laboratory.

In addition to the lid foils, there was optimistic news about the collector array. Team members from JPL arrived in Utah on Monday with a special fixture to aid in handling the science canister’s stack of four collector arrays. The stack was successfully removed as one piece. With the stack on the fixture, the team has begun the process of disassembling the arrays. Several large pieces of individual collector materials, including one completely intact hexagon, were recovered from the top array.

The Genesis cleanroom activities are focused on getting the materials ready for shipping. A date has not yet been selected for transporting the Genesis science canister and recovered collector materials from Dugway to NASA’s Johnson Space Center in Houston. The team continues its meticulous work and believes that a significant repository of solar wind materials has survived that will keep the science community busy working on their science objectives.

News and information about Genesis is available online at http://www.nasa.gov/genesis. For background information about Genesis, visit http://genesismission.jpl.nasa.gov. For information about NASA visit http://www.nasa.gov.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Biggest Collision in the Universe

With ESA?s XMM-Newton observatory, an international team of scientists has observed a nearby head-on collision of two galaxy clusters that has smashed together thousands of galaxies and millions upon millions of stars. It is one of the most powerful events ever witnessed. Such collisions are second only to the Big Bang in total energy output.

The event details what the scientists are calling the ?perfect cosmic storm?: galaxy clusters that collided like two high-pressure weather fronts and created hurricane-like conditions, tossing galaxies far from their paths and churning shock waves of 100-million-degree gas through intergalactic space.

This unprecedented view of a merger in action crystallises the theory that the Universe built its magnificent hierarchal structure from the ?bottom up? – essentially through mergers of smaller galaxies and galaxy clusters into bigger ones.

“Here before our eyes we see the making of one of the biggest objects in the Universe,” said Dr Patrick Henry of the University of Hawaii, who led the study. “What was once two distinct but smaller galaxy clusters 300 million years ago is now one massive cluster in turmoil.?

Henry and his colleagues, Alexis Finoguenov and Ulrich Briel of the Max-Planck Institute for Extraterrestrial Physics in Germany, present these results in an upcoming issue of the Astrophysical Journal. The forecast for the new super-cluster, they said, is ‘clear and calm’ now that the worst of the storm has passed.

Galaxy clusters are the largest gravitationally bound structures in Universe, containing hundreds to thousands of galaxies. Our Milky Way galaxy is part of a small group of galaxies but is not gravitationally bound to the closest cluster, the Virgo Cluster. We are destined for a collision in a few thousand million years, though.

The cluster named Abell 754 in the constellation Hydra has been known for decades. However, to the scientists’ surprise, the new observation reveals that the merger may have occurred from the opposite direction than what was thought. They found evidence for this by tracing the wreckage today left in the merger’s wake, spanning a distance of millions of light years. While other large mergers are known, none has been measured in such detail as Abell 754.

For the first time, the scientists could create a complete ?weather map? of Abell 754 and thus determine a forecast. This map contains information about the temperature, pressure and density of the new cluster. As in all clusters, most the ordinary matter is in the form of gas between the galaxies and not locked up in the galaxies or stars themselves. The massive forces of the merging clusters accelerated intergalactic gas to great speeds. This resulted in shock waves that heat the gas to very high temperatures, which then radiated X-ray light, far more energetic than the visible light our eyes can detect. XMM-Newton, in orbit, detects this type of high-energy light.

The dynamics of the merger revealed by XMM-Newton point to a cluster in transition. “One cluster has apparently smashed into the other from the ‘north-west’ and has since made one pass through,” said Finoguenov. “Now, gravity will pull the remnants of this first cluster back towards the core of the second. Over the next few thousand million of years, the remnants of the clusters will settle and the merger will be complete.”

The observation implies that the largest structures in the Universe are essentially still forming in the modern era. Abell 754 is relatively close, about 800 million light years away. The construction boom may soon be over in a few more thousand million years though. A mysterious substance dubbed ‘dark energy’ appears to be accelerating the Universe’s expansion rate. This means that objects are flying apart from each other at an ever-increasing speed and that clusters may eventually never have the opportunity to collide with each other.

X-ray observations of galaxy clusters such as Abell 754 will help to better define dark energy and also dark matter, an ?invisible? and mysterious substance that appears to comprise over 80 percent of a galaxy cluster’s mass.

This observation was announced at a NASA Internet press conference today. A paper describing these results, by Patrick Henry and his collaborators, will be published in the Astrophysical Journal.

Original Source: ESA News Release