See Doomed Spacecraft Before Its Fiery Demise

The Jules Verne Automated Transfer Vehicle (ATV) has done its duty – it even went above and beyond its expected capabilities. But the end is nigh, and soon, on September 29 the ATV will become a fireball and burn up in the Earth's atmosphere, never to be seen again. But before it does, people in North America and Europe have the perfect opportunity to see it sail overhead this weekend in its low Earth orbit, and according to Spaceweather.com, the ATV will glow about a brightly as the North Star, Polaris. To find out when and where to look for the ATV in the evening or early morning skies, check out Spaceweather.com's great satellite tracking webpage. Just plug in your zip code and you'll be able to get tracking information for all the satellites that will be visible for the next few days. Also, Heavens Above is a great site to find tracking information, as well. So get out there and bid Jules Verne adieu. Here's some of the great things the ATV accomplished while on orbit at the ISS, and a movie of its undocking too…

The Jules Verne spent five months docked to the space station where it delivered supplies (and fun things like a manuscript written by its namesake.) The supply ship turned into a tug boat when its engines were fired up to help the ISS avoid a piece of space junk. It also served as an impromptu bedroom for the space station crew.

When will the next ATV fly? Sometime in 2010, and the name for that ship has not yet been revealed. It will follow the debut of another space station cargo ship, Japan's H-2A Transfer Vehicle, set for next year.

Here's a movie of the Jules Verne undocking from the ISS.

Source: Spaceweather.com

The Moon Meets The Pleiades On September 19-20, 2008

Be sure to mark your calendar for tomorrow night. For lucky observers in northeastern North America, eastern Canada, and western Europe, the evening of September 19-20, 2008 is your opportunity to watch the face of the peaceful gibbous Moon glide across the ancient blue beauty of the Plieades…

On Friday night, September 19, 2008, observers in northeastern North America, eastern Canada need to be outdoors and ready when the Moon begins to rise low in the east-northeast. If you live in Western Europe, the event takes place high in the sky just before dawn on the morning of September 20th. Don't come alone, bring binoculars or a telescope with you, because this is your chance to see the stars first disappear behind the Moon's bright limb and then reappear on the dark side.

Super-massive and Small Black Holes Both Suck

Artist's impression of material falling into a super-massive black hole together with the average shape of the periodic X-ray signal from REJ1034+396. Credit: Aurore Simonnet, Sonoma State University

Sorry, couldn't resist that title. Astronomers studying black holes are able to "see" them due to the fact that the gas getting sucked in gets extremely hot and emits X-rays. These X-ray pulses are commonly seen among smaller black holes, but until now, had not been detected from super-massive black holes. But astronomers using the XMM Newton X-ray satellite have discovered a strong X-ray pulse emitting from a giant black hole in a galaxy 500 million light years from Earth, created by gas being sucked in by gravity. "Scientists have been looking for such behaviour for the past 20 years and our discovery helps us begin to understand more about the activity around such black holes as they grow," said Dr. Marek Gierlinski from Durham University. Gierlinski and his colleagues say this finding is the "missing link" between small and super-massive black holes.

The astronomers were looking at the center of the galaxy REJ1034+396 galaxy and found that X-rays are being emitted as a regular signal from the super-massive black hole. They say the frequency of the pulse is related to the size of the black hole. "Such signals are a well known feature of smaller black holes in our Galaxy when gas is pulled from a companion star," said Gierlinski. "The really interesting thing is that we have now established a link between these light-weight black holes and those millions of times as heavy as our Sun."

The scientists hope future research will tell them why some super-massive black holes show this behavior while others do not. Most galaxies, including the Milky Way, are believed to contain super-massive black holes at their centers.

The researchers, who publish their findings in the journal Nature on September 18, say their discovery will increase the understanding of how gas behaves before falling on to a black hole as it feeds and develops.

Distant object found orbiting Sun backwards

An object in the icy Kuiper belt has been found orbiting the Sun backwards, compared to most other objects in the solar system. It may help explain the origin of an enigmatic family of comets typified by Comet Halley.

The new object, called 2008 KV42, lies in the Kuiper belt, a ring of icy bodies beyond Neptune. Its orbit is inclined 103.5° to the plane of the Earth's orbit, or ecliptic. That means that as it orbits the Sun, it actually travels in the opposite direction to the planets.

Researchers led by Brett Gladman of the University of British Columbia first spotted the maverick object in May. Observations suggest it is about 50 kilometres across and travels on a path that takes it from the distance of Uranus to more than twice that of Neptune (or between 20 and 70 astronomical units from the Sun, with 1 AU being the Earth-Sun distance).

Its orbit appears to have been stable for hundreds of millions of years, but astronomers say it may have been born elsewhere. "It's certainly intriguing to ask where it comes from," says Brian Marsden of the Minor Planet Center in Cambridge, Massachusetts.

Gladman says it was probably born in the same place as Halley-type comets. These comets also travel on retrograde or highly tilted orbits – lasting between 20 and 200 years, but they come closer to the Sun.

It has been unclear where such comets come from. Computer models suggest they do not arise in either of the two birthplaces of other types of comets – the Kuiper belt or the much more distant Oort cloud, a shell of of icy bodies lying between 20,000 and 200,000 AU from the Sun.

Gladman's team calculates that 2008 KV42 arises beyond the Kuiper belt but closer than the Oort cloud, in a region thought to lie between 2000 to 5000 AU from the Sun. Some astronomers call the zone the inner Oort cloud.

A gravitational disturbance likely kicked 2008 KV42 out of the inner Oort cloud and to its present orbit. And Gladman says it might one day be pushed out of that orbit and into one that brings it closer to the Sun, making it a possible "transition object" on its way to becoming a Halley-type comet.

Gladman's team has found more than 20 other Kuiper belt objects with steeply inclined orbits while surveying the sky well away from the ecliptic – but no others with a retrograde orbit.

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

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)

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

Black Holes Can Only Get So Big

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

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

Explore Earth's Satellites with Google Earth

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

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!

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)

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