Universe Today

January 30, 2008December 26, 2015 by Nancy Atkinson

“Suits and Ties” Collaborate on Successful Space Station Repair

At the end of Wednesday’s successful spacewalk to change out a faulty motor on one of the International Space Station’s solar array positioning devices, the astronauts outside the ISS and flight controllers in Houston were congratulating each other on the group effort it took to pull off this particularly tricky and potentially dangerous repair job.

“You guys looked really good to us. Thanks for making it look so easy,” Mission Control in Houston radioed up to the spacewalkers after their seven-hour and 10 minutes EVA.

“Yeah,” said ISS astronaut Dan Tani. “And we did’t even have to put on a tie.”

This spacewalk really was a collaboration between the “suits and ties” at NASA. The suits — spacesuits, that is — were worn by astronauts Tani and Peggy Whitson. The ties were sported by the engineers and astronauts in Mission Control who planned the repair and guided the spacewalkers during the entire EVA.

Tani and Whitson were thanking one tie-wearing astronaut in particular. Tom Marshburn had practiced the choreography of the spacewalk in the Neutral Buoyancy Lab in Houston, and shared his insights with the spacewalkers. Usually astronauts get to practice their own EVA’s in the enormous pool that contains a mock-up of the ISS. But the Bearing Motor Roll Ring Module on the starboard solar array quit working in December when Whitson and Tani were already on board the station. So the plan and nuances of the EVA were tested in the pool by Marshburn and former ISS resident Suni Williams and relayed up to Tani and Whitson.

The spacewalk was especially hazardous because of the risk of electrical shock from 160 volts of electricity that flows through the arrays. For safety, Whitson and Tani waited until the International Space Station was on the dark side of Earth, giving them only 33 minute increments to complete their tasks. Whitson had to squeeze inside the station’s truss girder to swap out the 250 pound (113 kilograms) garbage can-sized motor.

The new motor successfully performed a 360-degree test spin during the spacewalk. It’s power-generating capabilities were tested successfully as well.

“Yay, it works!” exclaimed Whitson as she and Tani watched the solar wing turn. “Excellent, outstanding…isn’t that cool?”

The successful repair means the station should be able to generate enough power to support the new modules that will be brought on the next shuttle missions, the European Columbus science lab, and the Japanese Kibo labratory.

“Given the complexity of this spacewalk and the risks that we had to manage … we are exceptionally pleased with how things went,” flight director Kwatsi Alibaruho said after the EVA.

In addition to the motor repair, Whitson and Tani also performed another inspection of the station’s starboard Solar Alpha Rotary Joint, a 10-ft wide gear that keeps the solar wings pointing toward the sun The SARJ is not working and is contaminated with metal shavings. The spacewalkers evaluated damage from the debris and collected samples from areas previously unseen.

Alibaruho said the new debris samples will help determine what repairs will be done, perhaps later this year. NASA hopes to launch up to five shuttle flights to the ISS this year.

Wednesday’s EVA was the final planned spacewalk of the Expedition 16 mission and the 101st dedicated to space station assembly and maintenance. The spacewalk also marked the sixth career EVA’s for both Whitson and Tani.

So, there’s just one question for Dan Tani: Which is harder — donning a 280 lb spacesuit or tying a Windsor Knot?

Original News Source: NASA TV

January 30, 2008December 26, 2015 by Fraser Cain

Mercury is Less Like the Moon than Previously Believed

With Mercury fading in MESSENGER’s rear view mirror, scientists are just starting to pore through the torrent of images sent back. And as you can probably guess, the new mysteries are piling up fast and furious. The planet is much less like the Moon than scientists previously thought.

MESSENGER made its closest approach to Mercury on January 14, passing just a few hundred kilometres above its surface. During the flyby it captured a total of 1,213 images.

One of the most unique features discovered by MESSENGER has been dubbed “The Spider” by scientists. And that’s what it looks like. The feature has a central crater surrounded by more than a hundred narrow, flat-floored troughs (called graben) radiating away.

Unlike the Moon, Mercury has huge cliffs or scarps, which can snake hundreds of kilometres across the planet’s surface. They trace the lines of old volcanic faults, from when the planet was still geologically active.

Because of its small size and high density, Mercury has a surprisingly large pull of gravity. Astronauts walking around its surface would experience 38% of the Earth’s gravity. This higher gravity means that the impact craters look different. Material doesn’t splash out from the impact craters so far, and there are many more secondary crater chains.

â€œWe have seen new craters along the terminator on the side of the planet viewed by Mariner 10 where the illumination of the MESSENGER images revealed very subtle features. Technological advances that have been incorporated in MESSENGER are effectively revealing an entirely new planet from what we saw over 30 years ago,â€? said Science Team Co-Investigator Robert Strom, professor emeritus at the University of Arizona and the only member of both the MESSENGER and Mariner 10 science teams.

MESSENGER wasn’t just taking pictures. It also had a suite of scientific instruments measuring many features of the planet. Perhaps the most puzzling of these is its magnetic field. Even though Mercury cooled down and solidified eons ago, it still has an magnetic field. This was first detected by Mariner 10, and MESSENGER confirmed it.

This is just the beginning. MESSENGER will return to Mercury on October 6, 2008 to make a second flyby, and then a third on September 29, 2009. The spacecraft make its final return to the planet on March 18, 2011 when it’ll begin a year-long orbital mission.

Original Source: MESSENGER News Release

January 30, 2008December 26, 2015 by Fraser Cain

NASA Announces the Next Shuttle Launch Attempt: February 7, 2008

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After more than a month’s delays, the space shuttle Atlantis is finally ready to head back into space. NASA managers announced that they’ve targeted the shuttle for launch on February 7th, 2008 at 2:45 p.m. EST.

There’s one last little problem, though. Engineers inspecting the shuttle on Tuesday noticed a bent hose in its radiator cooling system. The hose runs from the shuttle body to the radiator panels on the cargo bay doors. It carries Freon to keep the shuttle’s systems cool in space.

So the question is: will the bend be a problem?

“Right now, that hose is perfectly functional,” Space Shuttle Program Manager Wayne Hale said. “Since the hose is not leaking now and the sister hose on Discovery didn’t leak on a number of flights, I’m feeling very positive we’ll come to a good conclusion. But we have to do our work here, the engineers have to do their work and we want to make sure we know what we’re doing before we go fly this vehicle.”

Even though it’s got this bent hose, the shuttle managers feel confident enough to launch Atlantis anyway. But they’re planning to meet again on Saturday to evaluate their testing, and think of any other problems that could happen.

Original Source: NASA Shuttle Status Report

January 30, 2008December 26, 2015 by Fraser Cain

Recovering from a Mass Extinction is Slow Going

With the diversity of life on Earth, and its ability to exploit every niche, you would think planet could bounce back from a devastating extinction event. Or maybe not. According to researchers from the University of Bristol, life took a full 30 million years to recover from the Permian extinction.

The poor animals alive during the Permian extinctions were struck by three waves of disaster. The largest of these happened at the boundary between the Permian and Triassic periods around 251 million years ago. Geologists think it was caused by large-scale volcanism in Russia which produced the ‘Siberian Traps’ – vast regions of lava 200,000 square km (77,000 square miles) in area. In a geologic heartbeat, 90% of all life on Earth was completely wiped out: insects, planets, marine animals, amphibians, and reptiles… everything. Life never got so close to being completely wiped off the face of the Earth.

Life did bounce back quickly, but diversity didn’t. Instead of the rich ecosystems we see today, very opportunistic creatures filled the empty spaces left behind by the extinction. One example is Lystrosaurus, a hardy herbivore the size of a pig.

Sarda Sahney and Professor Michael Benton at the University of Bristol looked at the recovery of animals like amphibians and reptiles. Although these creatures did make a recovery quickly, it took 30 million years for the number of animals and their diversity to match the pre-extinction levels.

Sahney said: â€œOur research shows that after a major ecological crisis, recovery takes a very long time. So although we have not yet witnessed anything like the level of the extinction that occurred at the end of the Permian, we should nevertheless bear in mind that ecosystems take a very long time to fully recover.â€?

This is an important thought to consider now that we’re in one of the most rapid periods of species loss in history.

Original Source: University of Bristol

January 30, 2008December 26, 2015 by Ian O'Neill

Innovative Laser Trap Captures Most Neutron-Rich Substance Made On Earth: Helium-8

Configuration of helium isotopes (credit: Physorg.com)

US researchers have used a new and innovative method to create, trap and study the elusive helium-8 isotope. Helium-8, containing six neutrons and only two protons, is the most neutron rich substance we can create on Earth and until now, we have been unable to accurately characterize it. Through the use of a “laser trap”, physicists in the U.S. Department of Energy’s Argonne National Laboratory have accurately mapped the distribution of theÂ atom and could help us understand the science behind exotic neutron stars.

So, how do you “trap” a helium-8 isotope? The answer is far from simple, but Argonne physicist Peter Mueller has found a solution. Using the GANIL cyclotron facility in northern France, helium-4, 6, and occasionally helium-8 isotopes can be generated. This is one of the only cyclotrons is the world with enough energy to generate the helium-8 isotope. It is all very well creating the particle, but to separate helium-8 from its other helium isotope siblings requires a clever and highly accurate laser “prison” for the heavier helium isotope to fall in to, whilst allowing the other, lighter, isotopes to fly straight through.

Acting as the “bars” of prison gates, six lasers are accurately aligned at such spacing that only isotopes with the dimensions of helium-8 are trapped. When aligned, helium-8 will fall between them, and should the isotope try to escape, repulsion forces keep the isotope still. Once enough time is allowed to pass (about one helium-8 atom is generated every two minutes) the team fire another two lasers into the middle at the same frequency as the resonant frequency of helium-8. Should the laser prison glow, helium-8 has been captured.

The most common, stable form of helium has two protons and two neutrons. Helium can also have two unstable isotopes, helium-6 (four neutrons) and helium-8 (six neutrons). In the unstable isotopes, the additional neutrons form a “halo” around the compact central core (pictured above). Helium-6 has a halo containing two neutrons and helium-8 has a halo of four neutrons. In the halo containing two neutrons, helium-6 has a distinctive “wobble” as the halo neutrons arrange themselves asymmetrically around the core (i.e. they bunch together). This lopsidedness moves the center of balance away from the core and more toward the halo pair of neutrons. Helium-8 on the other hand wobbles less as the four halo neutrons arrange themselves more symmetrically around the core. The laser trap is the only method known to trap a helium-8 atom, and because of this, the structure of its halo can finally be analyzed to such a high degree of accuracy.

To measure the characteristics of helium-8 is complicated by its radioactivity. Helium-8 has a half-life of only a tenth of a second, so all measurements of the atom must be taken instantly as the “prison glow” is detected. Measurements are therefore taken “on-line”, which is a difficult task in itself.

Detection of the rare helium-8 isotope is a major step to particle physicists and astrophysicists alike. It is important to understand how helium configures itself after production from a particle accelerator, but it is also of use when understanding the properties of cosmic bodies such as neutron stars. The implications of the Argonne experiment will be useful as better spectroscopic observations become available so the signature of the helium-8 structure might be detected other than on Earth.

Source: Physorg.com

January 30, 2008January 24, 2021 by Fraser Cain

Astrosphere for January 30, 2008

Your space photo for today is Saturn, captured by Mike Salway.

In his Cosmic Log, Alan Boyle talks about the state of science in the US after the recent State of the Union speech.

Phil debunks another Moon hoax claim.

Astronomy Picture of the Day has the closest photos of Asteroid 2007 TU24 during its recent flyby.

Ars Technica reports on a new video game based on Orson Scott Card’s Ender’s Game.

SPACE.com has the news of John Benac’s attempts to get space exploration policies at the forefront of the new election campaign.

For you southern hemispheroids, the February edition of the Southern Skywatch is up. Thanks to Ian Musgrave for the link.

Future astronauts are going to need to drink, so Colony Worlds has the solution.

January 30, 2008December 26, 2015 by Fraser Cain

New Technique for Finding Intermediate Mass Black Holes

It’s one of the big mysteries in astronomy. There are stellar mass black holes and the supermassive variety, but nothing in between. Where are all the intermediate mass black holes? Astronomers theorize that they could be located in globular star clusters, but nothing definitive has turned up yet. A team of researchers think they’ve come up with a new way to detect intermediate black holes – a way to see them for billions of light-years.

First a little background. When white dwarf stars are in a close binary system with another star, they pull off material, piling it up on their surface. When the white dwarf reaches 1.4 times the mass of our Sun, it reignites in a reaction that happens so quickly the star detonates. This is a Type 1a supernova, and astronomers use them as standard candles to determine distance since they always explode with the same amount of energy.

But researchers from UC Santa Cruz think there’s another situation where you might get a supernova explosion from a white dwarf: when it’s orbiting an intermediate mass black hole.

If a black hole has just the right amount of mass – 500 to 1000 times the mass of the Sun – a white dwarf might get torn apart in a particularly spectacular way. As the dwarf passes the whole, it would get compressed and heated. Its formerly dead material would now have the pressure and temperature to reignite in a powerful explosion similar to a Type 1a supernova.

The explosion would eject more than half of the debris into space, but the rest would fall back into the black hole and form an accretion disk around it. This disk would then emit X-ray radiation detectable by space telescopes like the Chandra X-Ray Observatory.

“This is a new mechanism for ignition of a white dwarf that results in a very different type of supernova than the standard type Ia, and it is followed by an x-ray source,” said Enrico Ramirez-Ruiz, assistant professor of astronomy and astrophysics at the University of California, Santa Cruz.

According to Ramirez-Ruiz, events like this would happen in about 1% of Type 1a supernova explosions. Future surveys, such as the Large Synoptic Survey Telescope, due for completion in 2013, is expected to discover hundreds of thousands of Type 1a supernovae each there. With those kinds of numbers, there should be many of these intermediate black hole interactions detected.

The mass of the white dwarf doesn’t really matter. They ran various sized stars through their simulation and found that you would still get the same outcome; the white dwarf would be tidally disrupted and then it would detonate.

Original Source: UC Santa Cruz News Release

January 30, 2008December 26, 2015 by Nancy Atkinson

A Young Star Grows Up

Remember when you were young and how Mom always told you to eat everything on your plate so you would get big? Well, there’s a young star heeding that advice about 2,600 light years from Earth in the constellation Monoceros. Known as MWC 147, this young stellar object is devouring everything on its “plate,” the disk of gas and dust that surrounds it. Astronomers are witnessing how this star is gaining mass, and is on its way to becoming an adult.

Using the Very Large Telescope Interferometer, ESO (European Organization for Astronomical Research in the Southern Hemisphere) astronomers have peered into the disc of material surrounding MWC 147, witnessing how the star gains its mass as it matures. This star is increasing in mass at a rate of seven millionths of a solar mass per year. Ah, these young stars. It seems like they grow up so fast these days.

MWC 147 is less than half a million years old. If our 4.6 billion year old Sun is considered to be middle-aged, MWC 147 would be a 1-day-old baby. This star is in the family of Herbig Ae/Be objects. These are stars that have a few times the mass of our Sun and are still forming, increasing in mass by swallowing material present in a surrounding disc.

Being 6.6 times more massive than the Sun, however, MWC 147 will only live for about 35 million years, or to draw again the comparison with a person, about 100 days, instead of the 80 year equivalent of our Sun.

We’re still learning about the morphology of the inner environment of these young stars, and everything we can discover helps us to better understand how stars and their surrounding planets form.

The observations by the ESO astronomers show that the temperature changes in this area are much steeper than predicted by current models, indicating that most of the near-infrared emission emerges from hot material located very close to the star, within one or two times the Earth-Sun distance (1-2 AU). This also implies that dust cannot exist so close to the star, since the strong energy radiated by the star heats up and ultimately destroys the dust grains.

“We have performed detailed numerical simulations to understand these observations and reached the conclusion that we observe not only the outer dust disc, but also measure strong emission from a hot inner gaseous disc. This suggests that the disc is not a passive one, simply reprocessing the light from the star,” explained astronomer Stefan Kraus. “Instead, the disc is active, and we see the material, which is just transported from the outer disc parts towards the forming star.”

Also of note is the beautiful image of the region surrounding MWC 147, which I’ll post below. The number of stars in this image is incredible, and is reminiscent of the â€œgrains of sandâ€? comment by Carl Sagan. This is a wide field image taken by Stephane Guisard of ESO with a 200 mm lens.

Original News Source: ESO Press Release

January 29, 2008December 26, 2015 by Tammy Plotner

Venus and Jupiter Dazzle the Eye on February 1

Although no one likes getting up early, the morning of February 1 will be worth the effort. Just before local dawn, the scene is set as brilliant planets Venus and Jupiter rise together ahead of sunrise. The planetary pair will be so close together they can easily fit in the same binocular field of view and in a low power, wide field telescope eyepiece. Even if you don’t use optical aid, the dazzling duet will capture the eye….

“Your eye is like a digital camera,” explains Dr. Stuart Hiroyasu, O.D., of Bishop, California. “There’s a lens in front to focus the light, and a photo-array behind the lens to capture the image. The photo-array in your eye is called the retina. It’s made of rods and cones, the fleshy organic equivalent of electronic pixels.” Near the center of the retina lies the fovea, a patch of tissue 1.5 millimeters wide where cones are extra-densely packed. “Whatever you see with the fovea, you see in high-definition,” he says. The fovea is critical to reading, driving, watching television. The fovea has the brain’s attention. The field of view of the fovea is only about five degrees wide. On Friday morning, Venus and Jupiter will fit together inside that narrow angle, signaling to the brain, “this is worth watching!”

But Venus and Jupiter aren’t the only pair sparkling the pre-dawn skies. If you look a bit further south, you’ll notice that the waning Moon and Antares are also making a spectacular show! While they will be separated by a little more distance, the red giant and earthshine Moon will still fit within the eye’s fovea – and a binocular field of view!

Where will all the celestial action take place? Look no further than the ecliptic plane – the imaginary path the Sun, Moon and planets take across the sky. For many observers, the ecliptic plane begins low in the southeast – but southern hemisphere viewers have a much different view! But don’t wait until Friday to have a look. If you’re up before dawn, step outside and watch as Venus and Jupiter draw closer together over the next several days and the Moon creeps to the east. On February 3, the Moon will form a line-up with the two planets and a striking triangle on the morning of February 4. Be sure to have a camera on hand and share your photos!

Wishing you clear skies….

January 29, 2008December 26, 2015 by Nancy Atkinson

Method to Test String Theory Proposed

Image of 10 dimensional super strings. Credit: PBS.

What is the universe made of? While general relativity does a good job providing insights into the Big Bang and the evolution of stars, galaxies and black holes, the theory doesn’t help much when it gets down to the small stuff. There are several theories about the basic, fundamental building blocks of all that exists. Some quantum physicists propose string theory as a theory of “everything,” that at the elemental heart of all matter lie tiny one-dimensional filaments called strings. Unfortunately, however, according to the theory, strings should be about a millionth of a billionth of a billionth of a billionth of a centimeter in length. Strings are way too small to see with current particle physics technology, so string theorists will have to come up with more clever methods to test the theory than just looking for the strings.

Well, one cosmologist has an idea. And it’s a really big idea.

Benjamin Wandelt, a professor of physics and astronomy at the University of Illinois says that ancient light from the beginnings of our universe was absorbed by neutral hydrogen atoms. By studying these atoms, certain predictions of string theory could be tested. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon. And it would be really gigantic: Wandelt proposes an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.

So for now, both string theory and this method of testing are purely hypothetical.

According to Wandelt, what this huge array would be looking for are absorption features in the 21-centimeter spectrum of neutral hydrogen atoms.

“High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation — called brane inflation– into string theory,” said Wandelt. “If we embed brane inflation into string theory, a network of cosmic strings is predicted to form. We can test this prediction by looking for the impact this cosmic string network would have on the density of neutral hydrogen in the universe.”

About 400,000 years after the Big Bang, the universe consisted of a thick shell of neutral hydrogen atoms (each composed of a single proton orbited by a single electron) illuminated by what became known as the cosmic microwave background.

Because neutral hydrogen atoms readily absorb electromagnetic radiation with a wavelength of 21 centimeters, the cosmic microwave background carries a signature of density perturbations in the hydrogen shell, which should be observable today, Wandelt said.

Cosmic strings are filaments of infinite length. Wandelt compared their composition to the boundaries of ice crystals in frozen water.

When water in a bowl begins to freeze, ice crystals will grow at different points in the bowl, with random orientations. When the ice crystals meet, they usually will not be aligned to one another. The boundary between two such misaligned crystals is called a discontinuity or a defect.

Cosmic strings are defects in space. String theory predicts that a network of strings were produced in the early universe, but this has not been detected so far. Cosmic strings produce fluctuations in the gas density through which they move, a signature of which Wandelt says will be imprinted on the 21-centimeter radiation.

Like the cosmic microwave background, the cosmological 21-centimeter radiation has been stretched as the universe has expanded. Today, this relic radiation has a wavelength closer to 21 meters, putting it in the long-wavelength radio portion of the electromagnetic spectrum.

If such an enormous array were eventually constructed, measurements of perturbations in the density of neutral hydrogen atoms could also reveal the value of string tension, a fundamental parameter in string theory, Wandelt said. “And that would tell us about the energy scale at which quantum gravity begins to become important.”

But questions remain about the validity of this experiment. Also, could the array somehow be “shrunk” to search only a small area of the 21-centimeter radiation? Or possibily, could an instrument similar to WMAP (Wilkinson Microwave Anisotropy Probe) be constructed to look at the entire sky for this radiation?

Wandelt and graduate student Rishi Khatri describe their proposed test in a paper accepted for publication in the journal Physical Review Letters, and the paper is not yet available for public review.

Original News Source: University of Illinois Press Release