Posted on by Tammy Plotner

The Fire Cracker Galaxy – NGC 6946 by Dietmar Hager

The FireCracker Galaxy - NGC 6946 by Dietmar Hager

[/caption]

It’s time to take a look back to what was happening 210 years ago on the night of September 9th. Sir William Herschel was at the eyepiece of his telescope in Slough. While he was viewing in real time, what he was viewing occurred more than 10 million years ago – the fireworks that ignited in NGC 6946.

At one time, it was widely believed that NGC 6946 was a member of our Local Group; mainly because it could be easily resolved into stars. There was a reddening observed in it, believed to be indicative of distance – but now know to be caused by interstellar dust. But it isn’t the shrouding dust cloud that makes NGC 6946 so interesting, it’s the fact that so many supernova and star-forming events have sparkled in its arms in the last few years that has science puzzled! So many, in fact, that they’ve been recorded every year or two for the last 60 years…

Most normally, bursts of star formation happen in galaxies which have nearby companions to lend materials. Yet, NGC 6946 appears to be alone in the field. According to a 2000 study done by Pisano (et al) ” Such gas-rich companions could include material left over from the galaxy assembly process which could persist into the current day around an isolated galaxy such as NGC 6946. NGC 6946 is prolifically forming stars, has a nuclear starburst, and has widespread high-velocity clouds associated with the disc. All of these features could be explained by the accretion of low-mass Hi clouds by NGC 6946. Our survey recovered two previously detected dwarf galaxies associated with NGC 6946, but otherwise found no signatures of interactions in the NGC 6946 system. The companions are small enough, and distant enough from NGC 6946 that they should have minimal effect on the main galaxy. Some tidal debris may be expected due to interaction between the two dwarf galaxies, but none is observed. This could be because it is at low column densities, or because the dwarf galaxies are more separated than they appear on the sky. This study of the system suggests that NGC 6946 is a gravitationally bound system with two dwarf galaxies in stable orbits about the larger primary galaxy.”

But, that was some 8 years ago and 16 events into the past. According to studies done by Eva Schinnerer (et al) in 2006, NGC 6946 has been “Caught in the Act” as a Bar-driven Nuclear Starburst Galaxy. “The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), allow the first detection of a molecular gas spiral in the inner ~10” (270 pc) with a large concentration of molecular gas (MH2~1.6×107 Msolar) within the inner 60 pc. This nuclear clump shows evidence for a ringlike geometry with a radius of ~10 pc as inferred from the position-velocity diagrams. Both the distribution of the molecular gas and its kinematics can be well explained by the influence of an inner stellar bar of about 400 pc length. A qualitative model of the expected gas flow shows that streaming motions along the leading sides of this bar are a plausible explanation for the high nuclear gas density. Thus, NGC 6946 is a prime example of molecular gas kinematics being driven by a small-scale, secondary stellar bar.”

Now, for the really cool part – understanding barred structure. Thanks to the Hubble Space Telescope and a study of more than 2,000 spiral galaxies – the Cosmic Evolution Survey (COSMOS) – astronomers understand that barred spiral structure just didn’t occur very often some 7 billion years ago in the local universe. Bar formation in spiral galaxies evolved over time. A team led by Kartik Sheth of the Spitzer Science Center at the California Institute of Technology in Pasadena discovered that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with nearly 70 percent of their modern counterparts. This makes NGC 6946 very rare, indeed… Since its barred structure was noted back in Herschel’s time and its age of 10 billion years puts it beyond what is considered a “modern” galaxy.

Science believes bars in galaxies have been forming steadily over the last 7 billion years, more than tripling in number. “The recently forming bars are not uniformly distributed across galaxy masses, however, and this is a key finding from our investigation,” Sheth explained. “They are forming mostly in the small, low-mass galaxies, whereas among the most massive galaxies, the fraction of bars was the same in the past as it is today.” The findings, Sheth continued, have important ramifications for galaxy evolution. “We know that evolution is generally faster for more massive galaxies: They form their stars early and fast and then fade into red disks. Low-mass galaxies are known to form stars at a slower pace, but now we see that they also made their bars slowly over time,” he said. Bars form when stellar orbits in a spiral galaxy become unstable and deviate from a circular path. “The tiny elongations in the stars’ orbits grow and they get locked into place, making a bar,” explained team member Bruce Elmegreen of IBM’s research Division in Yorktown Heights, N.Y. “The bar becomes even stronger as it locks more and more of these elongated orbits into place. Eventually a high fraction of the stars in the galaxy’s inner region join the bar.”

Added team member Lia Athanassoula of the Laboratoire d’Astrophysique de Marseille in France: “The new observations suggest that the instability is faster in more massive galaxies, perhaps because their inner disks are denser and their gravity is stronger.” Bars are perhaps one of the most important catalysts for changing a galaxy. They force a large amount of gas towards the galactic center, fueling new star formation, building central bulges of stars, and feeding massive black holes. “The formation of a bar may be the final important act in the evolution of a spiral galaxy,” Sheth said. “Galaxies are thought to build themselves up through mergers with other galaxies. After settling down, the only other dramatic way for galaxies to evolve is through the action of bars.” (HubbleSite News Release)

Yet the studies of NGC 6946 haven’t stopped. In 2005, Gemini II also took a look at this crazy galaxy. “In order to sustain this rate of supernova activity, massive, quickly evolving stars must form or be born at an equally rapid rate in NGC 6946,” said Gemini North Associate Director, Jean-René Roy. “Its stars are exploding like a string of firecrackers!” And with it in 2007, hydrogen halos… Says Rense Boomsma: “A halo of neutral hydrogen is found around an increasing number of spiral galaxies. It is not well understood how hydrogen halos are formed. The orientation of nearby spiral galaxy NGC 6946 enables us to measure vertical gas velocities in the disk of the galaxy and therefore measure how the gas gets into the halo. We find hydrogen with high velocities toward regions where stars are formed. This correlation suggests that the formation of a hydrogen halo is related to massive star formation. A similar close connection is seen in the nearby spiral galaxy NGC 253. For some hydrogen clouds in NGC 6946 we have indications that they have been accreted from outside the galaxy.”

Will we ever understand everything there is to know about galaxies like NGC 6946? Perhaps not in our lifetimes. However, one of the best parts is knowing that it is a galaxy that you can observe and study with larger backyard telescopes. Located in the constellation of Cepheus (RA 20:34.8 Dec +60:09) and billed at magnitude 8.9 (but beware, it’s low surface brightness!), this small barred spiral will show some structure in 10″ or larger scopes with decent skies. Who knows what your night may reveal?

Our many thanks to AORAIA member, Dr. Dietmar Hager of Stargazer Observatory for the use of this incredible image and the challenge of researching the information!

Link to original full size image.

Posted on by Nancy Atkinson

Opportunity Twitters Self Portrait

Opportunity self shadow portrait. Credit: NASA/JPL/Cornell

[/caption]

The Mars Exploration Rovers are now tweeting on Twitter, and Opportunity recently shared what she’s been doing since climbing out of Victoria crater via a shadow self portrait. After seeing a one-time electrical spike on Opportunity’s left front wheel, mission managers decided to have the rover climb out of the crater and get back on level ground. Opportunity is now examining some fist sized rocks, or cobbles, that might be ejecta from far away craters. Spirit, over on the other side of the Red Planet is weathering out the end of the southern hemisphere Martian winter. Another Twitter report from the rovers said that Spirit’s solar array energy is now up slightly from 235 to 245 watt hours. Power levels will have to rise a little more before Spirit can resume exploring actively.

Spirit's southern tilt. Credit: NASA/JPL/Cornell
Spirit's southern tilt. Credit: NASA/JPL/Cornell

Spirit has had to park on a north facing tilt in order to gather as much sunlight, and the image above shows the tilt. In the latest rover flight director video report, rover driver Scott Maxwell said the team is keeping an eye on the weather near Spirit’s, location watching for any rise in atmospheric dust. Dust has gathered on the rover’s solar panels, and any additional dust would hamper power levels as well. But so far everything is looking good, and Martian skies were actually clearer this past week.

Both rovers have been operating for more than 1,600 Martian sols, or days on Mars. A sol on Mars in about 40 minutes longer than an Earth day.

Posted on by Nancy Atkinson

Rosetta Flies By ‘Diamond in the Sky’ Steins

Mosaic of images from Rosetta's fly by. Credit: ESA

[/caption]

ESA’s Rosetta spacecraft successfully flew by the asteroid 2867 Steins, coming within 800 km (500 miles) and gathering images and data on the irregularly shaped rock in space. “Steins looks like a diamond in the sky,” said Uwe Keller, Principal Investigator for the OSIRIS imaging system on board the spacecraft. Watch a movie of the flyby here. Visible in the images are several small craters on the asteroid, and two huge ones. While the wide-angle camera worked perfectly during the flyby, the narrower and higher resolution camera switched itself off and into safe mode a few minutes before closest approach, but switched back on after a few hours. “The software switched off automatically,” said Gerhard Schwehm, Rosetta mission manager. “The camera has some software limits and we’ll analyze why this happened later.”

Rita Schulz, Rosetta Project Scientist, said, “In the images is a chain of impact craters, which must have formed from recurring impact as the asteroid rotated. The impact may have been caused by a meteoroid stream, or fragments from a shattered small body.”

The chain is composed of about 7 craters. To determine the age of the asteroid, a count of the craters on the asteroid’s surface has been started (the more the number of craters, the older the asteroid). So far, 23 craters have been spotted.

Steins in 3 D. Credit: ESA
Steins in 3 D. Credit: ESA

From the images, scientists will try and understand why the asteroid is unusually bright, and how fine grains of the surface regolith are. This will tell them more about how the asteroid formed. Images from the narrow angle camera are yet to be retrieved, and will help add to the knowledge of the surface composition and mineralogy.

“It looks like a typical asteroid, but it is really fascinating how much we can learn from just the images,” said Schwehm. “This is our first science highlight; we certainly have a lot of promising science ahead of us. I’m already looking forward to encountering our next diamond in the sky, the much bigger Lutetia.” Rosetta will meet up with asteroid (21) Lutetia on June 10, 2010.

What’s next for Rosetta? It will reach the maximum distance from the Sun on its current orbit on the 17th of December (2.26 AU) to head back to Earth for the next and last swing-by on the Nov. 13, 2009. After it flies by Lutetia, its final destination is going into orbit around Comet 67P/Churyumov-Gerasimenko in 2014.

Source: ESA

Posted on by Ian O'Neill

“Eight Minutes of Terror”: Solar Physicists Find a Supersonic Way to See the Transition Region

A Black Brant sounding rocket of the type that will carry SUMI above Earth's atmosphere (NASA)

[/caption]
Solar physicists will have the unprecedented opportunity to peer inside one of the most mysterious regions in the Sun’s atmosphere. Separating the chromosphere (at a temperature of a few thousand Kelvin) and the extended corona (at a temperature of over a million Kelvin) is a very thin layer about 5000 km above the photosphere (a.k.a. the Sun’s “surface”). The transition region dictates the characteristics of the hot plasma passing from the Sun into space and is right at the start of the solar-terrestrial chain, controlling space weather. We are unable to directly observe the transition region as it doesn’t radiate in wavelengths observable from the Earth’s surface, but it does emit UV radiation observable from space. So a group of solar researchers are packing some very sensitive instrumentation into a sounding rocket that will very briefly take some snapshots of the transition region. But they will have to be quick, from instrument deployment to re-entry, only eight minutes will be allowed to take the necessary UV spectroscopic observations…

To start us off, Jonathan Cirtain from the Marshall Space Flight Center explains this new mission in a nutshell:

“Early next year, we’re going to launch an experimental telescope that can measure vector magnetic fields in the transition region.” – Cirtain.

But why? Hasn’t the transition region been observed before? Actually, no. The surface of the Sun has been tirelessly studied, as has the solar atmosphere, but the thin layer separating the two has, so far, remained hidden from solar astronomers. “Just bad luck, really,” says Cirtain as he explains why the transition region has remained a mystery for so long. “Gas in the transition region doesn’t produce many strong spectral lines that we can see at visible wavelengths.” But it does radiate UV emission that can be observed from space, so Cirtain hopes his research group will be the first to peer right inside by pushing into space.

Coronal loops as viewed by the Transition Region and Coronal Explorer (TRACE)
Coronal loops as viewed by the Transition Region and Coronal Explorer (TRACE)

The transition region is critical to the understanding of the magnetic structure of the Sun and its corona. Below this thin layer, plasma pressure dominates, above it, magnetic pressure dominates. This means that above the transition region, the characteristics of the Sun’s magnetic field overwhelm the decreasing plasma pressure. The corona becomes a highly structured entity from the transition region and upward, which can be seen in the structure of magnetic coronal loops (pictured).

But what will they be measuring? How can the magnetic structure inside the transition region be seen? The instrument to be launched is called the Solar Ultraviolet Magnetograph Investigation (SUMI) and it is designed to measure the magnetic phenomenon of “Zeeman Splitting.” The Zeeman effect occurs when radiating plasma is in the presence of a strong magnetic field. So in the case of SUMI, the instrument will observe the UV emission from the transition region and detect the fine-scale splitting of the UV spectroscopic emission lines. The stronger the magnetic field, the greater the splitting.

SUMI can also measure the polarization of the split lines, so Cirtain’s team will have all the information they’ll ever need about the magnetic field in the transition region: both magnetic filed strength and direction. So far, so good.

But how is Cirtain planning on getting SUMI into space? To possibly make it cheap, and because SUMI is a comparatively simple instrument, it won’t need to be in space long. So the plan is to blast it into the lowest reaches of space on a sub-orbital flight inside the nose cone of a Black Brant sounding rocket. 68 seconds and 300 km (185 miles) into the flight, SUMI will be jettisoned. “We’ll be above more than 99.99% of Earth’s atmosphere. From that moment, we’ve only got 8 minutes to work with. We’ll target an active region and start taking data,” Cirtain added.

Carrying out short sounding rocket missions is not new to solar physics, some of the very first space-based observations of the Sun could only come from high altitude rockets. However, Cirtain will be nervous to see SUMI disappear into the stratosphere at 5,000 mph and has dubbed the flight the “Eight minutes of terror.”

So, from one of the simplest and cheapest observation campaigns, the mysterious transition region may start to give us some answers…

Source: NASA

Posted on by Ian O'Neill

Goodbye Jules Verne: ATV Undocks From Station

The scene inside ESA mission control as the ATV backs away from the station (ESA)

[/caption]
Europe’s most advanced robotic spaceship, the Automated Transfer Vehicle (ATV), has effectively ended its 6-month mission to the International Space Station (ISS). It successfully undocked today (Friday) at 21:29 GMT to begin its slow 3 week journey toward the Earth’s atmosphere where it is set for re-entry on September 29th. This was the first ever ATV to be launched and was named after the 19th Century novelist, Jules Verne; another four ATVs are scheduled for construction. Jules Verne’s re-entry is set for night time over an uninhabited region of the Pacific Ocean and NASA will use this opportunity to monitor the fireball so the characteristics of re-entering spacecraft can be studied…

It might seem like a waste – after all, the ATV cost 1.3 billion euros or 1.9 billion dollars to build – but Jules Verne was designed to be a single-use, disposable resupply ship for the space station. However, its duties as a supply ship weren’t restricted to grocery deliveries. After it was launched in March, the ATV underwent a series of tests in space to prepare it for arrival at the station on April 3rd. When attached to the station, the ATV surpassed all expectations and performed many tasks that hadn’t been considered by mission control. Although the ATV provided a valuable re-boost option for the station (four times in total), it also provided the thrust to slow the ISS down to avoid a chunk of satellite debris in August. The ship was also a welcome retreat for the crew of the station, giving them a roomy volume for recreation and cleaning chores. I think Jules Verne will be sorely missed.

So, like the Russian Progress 29 resupply ship that was dropped from the station on Wednesday, Jules Verne was packed up with several tonnes of trash and unwanted equipment from the ISS and jettisoned into space.

The ATV will now use its remaining fuel to park its 13.5 tonne mass in a new orbit for the following three weeks before it is commanded to drop from orbit and begin re-entry. Jules Verne’s fiery suicide will happen at night so scientists can gain an insight into how large objects behave when they burn up in the Earth’s atmosphere. To monitor the event, NASA will deploy two aircraft with radar, UV and other sensors to track the incoming ATV.

“Even though our schedule has been very busy at the ATV Control Centre, I couldn’t have wished for a better mission,” – Herve Come, ESA’s ATV lead mission director.

Sources: ESA, AFP

Posted on by Ian O'Neill

Kuiper Belt Object Travelling the Wrong-Way in a One-Way Solar System

Artist impression of two KBOs and Neptune eclipsing the Sun (Mark A. Garlick)

[/caption]
A strange Kuiper Belt Object (KBO) has been discovered orbiting the Sun in the wrong direction. The object, designated as 2008 KV42 but nicknamed Drac (after Dracula, as vampires are fabled to have the ability to walk on walls), has a highly inclined orbit of 103.5°. Drac is a rarity as very few objects in the Solar System have retrograde orbits; in fact this kind of orbit is usually exclusive to Halley-type comets that have orbits that take them very close to the Sun. Drac on the other hand travels through the Kuiper Belt in a stable orbit at a distance of between 20-70 AU from the Sun. This finding has puzzled astronomers, but Drac may provide clues as to where Halley-type objects originate…

When an object has an inclination of more than 90° from the ecliptic, its direction of motion becomes retrograde when compared with the majority of the Sun’s satellites that share a common, or “prograde” orbital direction. This type of orbit is usually reserved for long-period comets thought to originate from the mysterious Oort Cloud. However, Drac stands out from the crowd as it orbits the Sun from the distance of Uranus to more than twice that of Neptune. Halley-type comets come much closer to the Sun.

The orbit of Drac - animation (CFEPS)
The orbit of Drac - animation (CFEPS)

Researchers led by Brett Gladman of the University of British Columbia observed the 50 km (30 mile) diameter object in May. Drac (or 2008 KV42) appears to have an extremely stable orbit, and its possibly been that way for hundreds of millions of years. Although Drac orbits through the Kuiper Belt, astronomers do not believe it originates there. “It’s certainly intriguing to ask where it comes from,” says Brian Marsden of the Minor Planet Center in Cambridge, Massachusetts.

Gladman believes the object originated far beyond the Kuiper Belt, possibly from the same volume of space believed to breed Halley-type comets with highly tilted (often retrograde) orbital periods of between 20-200 years. Gladman and his colleagues believe Drac came from a region beyond the Kuiper Belt, but it didn’t come from the Oort Cloud (some 20,000 to 200,000 AU from the Sun). The researchers believe 2008 KV42 was born in a region 2000-5000 AU from the Sun, a theorized volume of the Solar System called the inner Oort Cloud.

It seems likely that Drac was gravitationally disturbed from its home in the inner Oort Cloud by a passing star, or some other disturbance in its local space. It then fell toward the inner Solar System where it found its new home near the Kuiper Belt. Gladman believes that 2008 KV42 may be a “transition object” on its way to becoming a Halley-type comet. However, it will need to be disturbed again before it breaks free of its current stable orbit to fall closer to the Sun.

The British Columbia team have found a collection of 20 KBOs with steeply inclined orbits, but Drac, the vampire of the Solar System, is the only one orbiting in the wrong direction…

Source: New Scientist

Posted on by Nancy Atkinson

Black Holes Can Only Get So Big

Ultra-massive black holes, which lurk in the centers of huge galaxy clusters like the one above, seem to have an upper mass limit of 10 billion times that of the Sun. (Credit: NASA)

[/caption]
Black holes are thought to exist throughout the universe, with the largest and most massive found at the centers of the largest galaxies. These supermassive black holes have been shown to have masses upwards of one billion times that of our own Sun. But an astronomer studying black holes says there’s an upper limit to how big a black hole can get. Priyamvada Natarajan, an associate professor of astronomy and physics at Yale University has shown that even the biggest of these gravitational monsters can’t keep growing forever. Instead, they appear to curb their own growth – once they accumulate about 10 billion times the mass of the Sun.

These ultra-massive black holes, found at the centers of giant elliptical galaxies in huge galaxy clusters, are the biggest in the known universe. Even the large black hole at the center of our own Milky Way galaxy is thousands of times less massive than these behemoths. But these gigantic black holes, which accumulate mass by sucking in matter from neighboring gas, dust and stars, seem unable to grow beyond this limit regardless of where – and when – they appear in the universe. “It’s not just happening today,” said Natarajan. “They shut off at every epoch in the universe.”

Natarajan’s study is the first time an upper mass limit has been derived for black holes. Natarajan used existing optical and X-ray data of these ultra-massive black holes to show that, in order for those various observations to be consistent, the black holes must essentially shut off at some point in their evolution.

Artist's conception of a black hole. Credit: U of Tel Aviv
Artist's conception of a black hole. Credit: U of Tel Aviv

One possible explanation, says Natarajan, is that the black holes eventually reach the point when they radiate so much energy as they consume their surroundings that they end up interfering with the very gas supply that feeds them, which may interrupt nearby star formation. The new findings have implications for the future study of galaxy formation, since many of the largest galaxies in the universe appear to co-evolve along with the black holes at their centers.

“Evidence has been mounting for the key role that black holes play in the process of galaxy formation,” said Natarajan. “But it now appears that they are likely the prima donnas of this space opera.”

Source: PhysOrg

Posted on by Ian O'Neill

Explore Earth’s Satellites with Google Earth

It's getting crowded out there: active and inactive satellites are tracked (Google/Analytical Graphics)

[/caption]
OK, I’ve just wasted an hour in simulated space, checking out some of the active and junked satellites orbiting our planet. Google Earth can be an addictive thing at the best of times, but when 13,000 of the satellites in Earth orbit can be viewed by a new plug-in for the program, you may find yourself hooked for longer than usual. The United States Strategic Command keeps very close tabs on what is orbiting our planet and where they are at any given time, and now with the help of Google Earth, you can explore the satellites, plot their orbital trajectories and see just how crowded space can be. Never before have geostationary communication satellites been so interesting!

playing around with the orbital trajectory option (Google/Analytical Graphics)
Just trackin': playing around with the orbital trajectory option (Google/Analytical Graphics)

Tracking space junk is paramount to all our activities in space. Every time we put a “useful” satellite into orbit – to service our communication needs, monitor the weather or spy on other countries – we are amplifying the growing space junk problem surrounding Earth. In February, I wrote a Universe Today article reporting on Google Earth’s ability to plot all known bits of space junk orbiting the Earth. I think it shocked many to see the problem in dazzling 3D. Now a new plug-in has been released detailing the positions of 13,000 alive and dead satellites being tracked by the US military.

At the end of last month, the danger of discarded satellite parts became all too real for the crew of the International Space Station. Nancy wrote about the heroic efforts of the (soon to be dumped) ATV that boosted the station clear of passing debris from a disintegrated Russian satellite. According to officials, the ATV carried out a 5 minute burn, slowing the station and lowering its orbit by 1.5 km (1 mile). The chunk of Russian spy satellite was allowed to pass without incident.

InSat-4, active communications satellites serving India. They're in geosynchronous orbit don't you know? (Google/Analytical Graphics)
InSat-4, active communications satellites serving India. They're in geosynchronous orbit don't you know? (Google/Analytical Graphics)

Now you can see the space debris being carefully watched by the US and do some satellite tracking yourself. This new Google Earth plug-in (.kmz file for Google Earth) allows you not only to get information on the 13,000 objects tracked by the US Strategic Command, it also lets you plot their orbits. All the way from low Earth to geostationary orbits, you can access information about who launched the satellite, whether it is active or not, its launch date, mass and orbital information (apogee/perigee). By clicking “Display Trajectory in Fixed Frame” in the information panel that appears when you select the satellite, the orbital path is displayed. It is worth noting that this is the orbital trajectory in relation to the Earth’s rotation (or the “fixed frame”), so geostationary satellites will appear to have no orbital motion, as you’d expect.

I spent a long time clicking on the various satellites, constantly surprised by the huge number of inactive satellites there were. I also checked out some information on satellites I’d never heard of (like the active InSat-3A/4B geostationary communication satellites I found oscillating around each other, pictured).

Although it is shocking to see the sheer number of satellites out there (reminding me that Kessler Syndrome could be a very real threat in the future), learning about the stuff orbiting Earth was great fun.

Source: Slashdot

Posted on by Nancy Atkinson

New Report: LHC Switch-on Fears Are Completely Unfounded

Large Hadron Collider. Credit: NY Times

[/caption]

We don’t mean to beat a dead horse – both Fraser and Ian have already covered this topic quite thoroughly — but just in case anyone still has any fears about the Large Hadron Collider meaning the end of the world, a new report published today provides the most comprehensive evidence available to confirm that the LHC’s switch-on, due on Wednesday next week, poses no threat to mankind. A copy of the report is available HERE. In a nutshell, it says nature’s own cosmic rays regularly produce more powerful particle collisions than those planned within the LHC, and nothing bad has happened to Earth from those quite natural and frequent events. The LHC will be studying nature’s laws in controlled experiments. So just relax and watch the LHC rap video.

The LHC Safety Assessment Group have reviewed and updated a study first completed in 2003, which dispels fears of universe-gobbling black holes and of other possibly dangerous new forms of matter, and confirms that the switch-on will be completely safe.

The report, ‘Review of the Safety of LHC Collisions’, published in IOP Publishing’s Journal of Physics G: Nuclear and Particle Physics, proves that if particle collisions at the LHC had the power to destroy the Earth, we would never have been given the chance to exist, because regular interactions with more energetic cosmic rays would already have destroyed the Earth or other astronomical bodies.

The Safety Assessment Group compares the rates of cosmic rays that bombard Earth, other planets in our solar system, the Sun and all the other stars in our universe itself to show that hypothetical black holes or strangelets, that have raised fears in some, will in fact pose no threat.

The report also concludes that, since cosmic-ray collisions are more energetic than those in the LHC, but are incapable of producing vacuum bubbles or dangerous magnetic monopoles, we should not fear their creation by the LHC.

LHC collisions will differ from cosmic-ray collisions in that any exotic particles created will have lower velocities, but the Safety Assessment Group shows that even fast-moving black holes produced by cosmic rays would have stopped inside the Earth or other astronomical bodies. Their existence proves that any such black holes could not gobble matter at a risky rate.

As the Safety Assessment Group writes, “Each collision of a pair of protons in the LHC will release an amount of energy comparable to that of two colliding mosquitoes, so any black hole produced would be much smaller than those known to astrophysicists.” They conclude that such microscopic black holes could not grow dangerously.

As for the equally hypothetical strangelets, the review uses recent experimental measurements at the Brookhaven National Laboratory’s Relativistic Heavy-Ion Collider, New York, to prove that they will not be produced during collisions in the LHC.

Source: EurekAlert

Posted on by Nancy Atkinson

Sleek, Sexy Spacecraft to Launch Next Week

GOCE: Spacecraft of the future is here! Credit: ESA

[/caption]
This has to be the sexiest looking spacecraft ever built by humankind. No, it’s not a starship or battle cruiser (although it does look a little like the Eagle spacecraft from the old television show Space: 1999). This sleek, slender, sexy, shiny and sophisticated spacecraft is an Earth-orbiting satellite that will investigate our planet’s gravitational field and map the reference shape of our planet – the geoid – with unprecedented resolution and accuracy. GOCE, or the Gravity field and steady-state Ocean Circulation Explorer is scheduled to launch on Wed. September 10 at 16:21 CEST (14:21 UTC). Why such a sleek design? As GOCE Systems Manager Michael Fehringer says, “Form follows function not only in the world of fashion! To fly low and avoid air drag, the best shape for the satellite to be is long, slender and absolutely symmetrical along the direction of flight.”

ESA’s 1 ton, 5 meter-long spacecraft will be in an extra low orbit (260 km, or 161 miles) and will experience drag from Earth’s upper atmosphere, so smooth and lean helps reduce the friction. Adding to the sleek design is that the solar panels are attached to the long body of the satellite instead of sticking out clumsily and adding to the drag. ESA has a great animation of GOCE in flight. Although the design will help, the spacecraft will need a boost to its orbit occasionally, and has state of the art ion engines.

GOCE on the launchpad. Credit: ESA
GOCE on the launchpad. Credit: ESA

GOCE will be in a sun-synchronous orbit, meaning it will be almost always be in sunlight, providing a stable thermal environment for the spacecraft.

The instruments are all placed along the axis of the satellite’s body, adding to its sleekness — check out this great animation. GOCE carries a set of six state-of-the-art high-sensitivity accelerometers to measure the components of the gravity field along all three axes. The data collected will provide a high-resolution map of the geoid and of gravitational anomalies. This will greatly improve our knowledge and understanding of the Earth’s internal structure, and will be used as a much-improved reference for ocean and climate studies, including sea-level changes, oceanic circulation and ice caps dynamics survey. Numerous applications are expected in climatology, oceanography and geophysics, as well as for geodetic and positioning activities.

Here’s an interactive feature to take a closer look at the spacecraft.

Oooo. It’s enough to make a girl purr.

Source: ESA
Also, check out Ian’s article on Astroengine