Following Monday’s successful launch of the space shuttle, Atlantis and her crew are well on their way to rendezvous with the Hubble Space Telescope on Wednesday. During their first full day in orbit, the STS-125 crew members will inspect Atlantis’ heat shield for any problems that may have occurred during launch. Despite the picture perfect liftoff, there were a couple of issues during launch — a couple of alarms went off (more on those below.) If you missed the launch (like I did) or want to see it again, here’s a chance to watch it in HD. Also, below watch an HD video of the external tank falling to Earth, taken by a new high definition camera system.
Continue reading “Atlantis HD Launch Video; Heat Shield Inspection Today”
Unusual Cargo Headed to Hubble: A Basketball?
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Most people know Edwin Hubble as a famed astronomer, but he also starred as a forward on the University of Chicago Maroons’ Big Ten champion basketball teams of 1907–08 and 1908–09.
And as fellow Chicago alumnus John Grunsfeld has prepared for his fifth space shuttle flight since 1995, he’s been pondered how best to deflate a century-old ball that Hubble had tossed around in a 1909 victory against Indiana University.
The challenge: Find a way to compactly stow the old pigskin, which to everyone’s surprise lacks an air valve, aboard the space shuttle Atlantis for its upcoming launch.
The problem unfolded last summer in a series of e-mails between Grunsfeld and Michael Turner, a University of Chicago astronomy and astrophysics professor.
“It’s a cosmic mystery as to how the ball was filled, and now for me how to drain it,” Grunsfeld told Turner, who had borrowed the basketball from the university’s athletics program for its orbital flight. Grunsfeld plans to return the basketball personally to the University after the mission, when it will go on display.
“We couldn’t find a valve to deflate it, so we will leave it to the rocket scientists to figure out how to flatten it,” Turner told Grunsfeld. It presented another challenge of the kind that Grunsfeld relishes, but would never have anticipated as an astronaut.
Five weeks before scheduled launch, Grunsfeld punctured the basketball with a hypodermic needle. “Nothing happened, no air hissing out, or any air transfer at all as I compressed the ball,” he said. Grunsfeld assumed that he had punctured the pigskin, but not the underlying air bladder. And yet more punctures with different needles in different locations also failed to deflate the ball.
Finally, with the University’s permission, Grunsfeld resorted to cutting a small incision into the ball. “To my astonishment, I discovered that there is no bladder, and no pressurized air. The basketball was filled with an organic fiber packing,” he said.
Grunsfeld plans to reshape the ball while in orbit and gently pass it around to crewmates during a photo-op. The moment should provide a memorable, light-hearted counterpoint to his usual orbital workload of marathon spacewalks and Hubble Telescope repairs.
Final Pretty Picture for Hubble Camera
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Last week we looked back at some of the greatest images and discoveries produced by the Hubble Space Telescope’s Wide Field Planetary Camera 2, the workhorse optical camera that will be replaced with the new and improved WFPC3 during the Hubble servicing mission this week. Now, in tribute to the legacy of WFPC2, the telescope’s science team has released this image as the camera’s final “pretty picture,” a planetary nebula is known as Kohoutek 4-55 (or K 4-55). This image is the last hurrah for the camera that has provided outstanding science and spectacular images of the cosmos.
K 4-55 is nearly 4,600 light-years away in the constellation Cygnus. It is one of a series of planetary nebulae that were named after their discoverer, Czech astronomer Lubos Kohoutek. A planetary nebula contains the outer layers of a red giant star that were expelled into interstellar space when the star was in the late stages of its life. Ultraviolet radiation emitted from the remaining hot core of the star ionizes the ejected gas shells, causing them to glow.
In the specific case of K 4-55, a bright inner ring is surrounded by a bipolar structure. The entire system is then surrounded by a faint red halo, seen in the emission by nitrogen gas. This multi-shell structure is fairly uncommon in planetary nebulae.
The colors represent the makeup of the various emission clouds in the nebula: red represents nitrogen, green represents hydrogen, and blue represents oxygen.
This Hubble image was taken by the Wide Field and Planetary Camera 2 on May 4, 2009.
The scientific and inspirational legacy of the camera will be felt by astronomers and the public alike, for as long as the story of the Hubble Space Telescope is told.
Source: HubbleSite
Astronomers Closing in on Dark Energy with Refined Hubble Constant
The name “dark energy” is just a placeholder for the force — whatever it is — that is causing the Universe to expand. But astronomers are perhaps getting closer to understanding this force. New observations of several Cepheid variable stars by the Hubble Space Telescope has refined the measurement of the Universe’s present expansion rate to a precision where the error is smaller than five percent. The new value for the expansion rate, known as the Hubble constant, or H0 (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6). The results agree closely with an earlier measurement gleaned from Hubble of 72 ± 8 km/sec/megaparsec, but are now more than twice as precise.
The Hubble measurement, conducted by the SHOES (Supernova H0 for the Equation of State) Team and led by Adam Riess, of the Space Telescope Science Institute and the Johns Hopkins University, uses a number of refinements to streamline and strengthen the construction of a cosmic “distance ladder,” a billion light-years in length, that astronomers use to determine the universe’s expansion rate.
Hubble observations of the pulsating Cepheid variables in a nearby cosmic mile marker, the galaxy NGC 4258, and in the host galaxies of recent supernovae, directly link these distance indicators. The use of Hubble to bridge these rungs in the ladder eliminated the systematic errors that are almost unavoidably introduced by comparing measurements from different telescopes.
Riess explains the new technique: “It’s like measuring a building with a long tape measure instead of moving a yard stick end over end. You avoid compounding the little errors you make every time you move the yardstick. The higher the building, the greater the error.”
Lucas Macri, professor of physics and astronomy at Texas A&M, and a significant contributor to the results, said, “Cepheids are the backbone of the distance ladder because their pulsation periods, which are easily observed, correlate directly with their luminosities. Another refinement of our ladder is the fact that we have observed the Cepheids in the near-infrared parts of the electromagnetic spectrum where these variable stars are better distance indicators than at optical wavelengths.”
This new, more precise value of the Hubble constant was used to test and constrain the properties of dark energy, the form of energy that produces a repulsive force in space, which is causing the expansion rate of the universe to accelerate.
By bracketing the expansion history of the universe between today and when the universe was only approximately 380,000 years old, the astronomers were able to place limits on the nature of the dark energy that is causing the expansion to speed up. (The measurement for the far, early universe is derived from fluctuations in the cosmic microwave background, as resolved by NASA’s Wilkinson Microwave Anisotropy Probe, WMAP, in 2003.)
Their result is consistent with the simplest interpretation of dark energy: that it is mathematically equivalent to Albert Einstein’s hypothesized cosmological constant, introduced a century ago to push on the fabric of space and prevent the universe from collapsing under the pull of gravity. (Einstein, however, removed the constant once the expansion of the universe was discovered by Edwin Hubble.)
“If you put in a box all the ways that dark energy might differ from the cosmological constant, that box would now be three times smaller,” says Riess. “That’s progress, but we still have a long way to go to pin down the nature of dark energy.”
Though the cosmological constant was conceived of long ago, observational evidence for dark energy didn’t come along until 11 years ago, when two studies, one led by Riess and Brian Schmidt of Mount Stromlo Observatory, and the other by Saul Perlmutter of Lawrence Berkeley National Laboratory, discovered dark energy independently, in part with Hubble observations. Since then astronomers have been pursuing observations to better characterize dark energy.
Riess’s approach to narrowing alternative explanations for dark energy—whether it is a static cosmological constant or a dynamical field (like the repulsive force that drove inflation after the big bang)—is to further refine measurements of the universe’s expansion history.
Before Hubble was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to an error of only about ten percent. This was accomplished by observing Cepheid variables at optical wavelengths out to greater distances than obtained previously and comparing those to similar measurements from ground-based telescopes.
The SHOES team used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys (ACS) to observe 240 Cepheid variable stars across seven galaxies. One of these galaxies was NGC 4258, whose distance was very accurately determined through observations with radio telescopes. The other six galaxies recently hosted Type Ia supernovae that are reliable distance indicators for even farther measurements in the universe. Type Ia supernovae all explode with nearly the same amount of energy and therefore have almost the same intrinsic brightness.
By observing Cepheids with very similar properties at near-infrared wavelengths in all seven galaxies, and using the same telescope and instrument, the team was able to more precisely calibrate the luminosity of supernovae. With Hubble’s powerful capabilities, the team was able to sidestep some of the shakiest rungs along the previous distance ladder involving uncertainties in the behavior of Cepheids.
Riess would eventually like to see the Hubble constant refined to a value with an error of no more than one percent, to put even tighter constraints on solutions to dark energy.
End of an Era: The Hubble WFPC2’s Greatest Hits
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For 15 years, the Hubble Space Telescope’s Wide Field and Planetary Camera 2 (WFPC2) has been churning out amazing and breathtaking images of our universe. But during the upcoming HST servicing mission, a new and improved version of Hubble’s main camera will replace the optical workhorse that has provided so many memorable and awe-inspiring images. WFPC2 was brought up on orbit to Hubble in December of 1993 to replace the original camera, outfitted with special optics to overcome the spherical aberration in Hubble’s main mirror. To honor the WFPC2, here are a few of the most memorable discoveries the camera has made.
Hubble Deep Field. Above is one of the most incredible images ever, the Hubble Deep Field. Over 10 consecutive days in December 1995, Hubble and the WFPC2 2 stared at a speck of sky no bigger than a grain of sand held at arm’s length. In that small patch of sky, more than 1,000 galaxies located billions of light-years away were revealed, each containing billions of stars. Our world and our galaxy suddenly seemed very small.
Pillars of Creation.
Imaged by the camera on April 1, 1995, the Eagle Nebula, 7,000 light-years away, is composed of dense, towering clusters of interstellar hydrogen, oxygen and sulfur, trillions of kilometers long. Emerging from these towers of cosmic material are stars being born.
“After we released the image during a press conference, CNN continued to cover the story live,” said Ed Weiler, acting assistant administrator for NASA’s Science Mission Directorate in Washington. “People felt compelled to call in with their reactions to this one picture…Some called it the pillars of creation. This picture touched Americans in a way I have never seen an astronomical picture do.”
Comet collision with Jupiter. WFPC2 gave the world a rare, stunning view of Comet Shoemaker-Levy 9 plunging into Jupiter in 1994. The images revealed the event in great detail, including ripples expanding outward from the impact.
Determining the age and rate of expansion of our universe. Our universe formed from a colossal explosion known as the Big Bang, and has been stretching apart ever since. Using WFPC2 to observe stars that vary periodically in brightness, astronomers were able to calculate the pace of this expansion to an unprecedented degree of error of 10 percent. The camera also played a leading role in discovering that the expansion of the universe is accelerating, driven by a mysterious force called “dark energy.” Together, these findings led to the calculation that our universe is approximately 13.7 billion years old.
Most galaxies harbor huge black holes. Before Hubble, astronomers suspected, but had no proof, that supermassive black holes lurk deep in the bellies of galaxies. The Wide Field and Planetary Camera 2, together with spectroscopy data from Hubble, showed that most galaxies in the universe do indeed harbor monstrous black holes up to billions of times the mass of our sun.
Source: JPL
Hubble Servicing Mission Meets the Big Screen; Watch With Friends
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The crew of the upcoming Hubble servicing mission have not only been busy training for all contingencies of spaceflight on the shuttle and telescope repair (have you been following Astro_Mike on Twitter?) but they’ve also been training for the big screen. The REALLY big screen. NASA announced today that the crew will be using IMAX 3-D cameras to document this most complex of space shuttle operations — the final servicing mission to the Hubble Space Telescope. And in another bit of news, in a show of solidarity and support of the shuttle astronauts, astronomers from the University of Alabama are encouraging everyone to “raise a wing” to the Hubble repair crew.
The IMAX 3-D cameras will launch aboard space shuttle Atlantis, which is scheduled to lift off May 11. Astronauts will use the cameras to film five spacewalks needed to repair and upgrade Hubble. The IMAX footage will be combined with images from Hubble itself to create a new IMAX producton, “Hubble 3D,” set for release in spring 2010.
“We have worked with IMAX on past Hubble missions and are excited about working with them again on the current Hubble mission. The Hubble Space Telescope continues to dazzle us with the splendor of our universe, and after the mission we look forward to many more years of awe-inspiring imagery,” said Bob Jacobs, NASA’s acting assistant administrator for public affairs at NASA Headquarters in Washington. “IMAX has developed innovative 3-D image capture and projection technology that creates a large-scale, immersive educational experience in which those of us on the ground are no longer passive observers of spaceflight, we’re active participants.”
The IMAX team has trained Atlantis’ crew at NASA’s Johnson Space Center in Houston to operate the cameras. One will be mounted outside the crew cabin in the shuttle’s cargo bay to capture IMAX 3-D images of the historic final servicing mission. The commander and pilot will double as filmmakers as two teams of spacewalking astronauts — working in tandem with the shuttle’s robotic arm — perform some of the most challenging work ever undertaken in space as they replace and refurbish many of the telescope’s precision instruments.
And now for more on “raising a wing” to the crew, which came to us via Pamela Gay: Dr. William Keel of the University of Alabama Department of Physics and Astronomy is planning to head to the local Buffalo Wild Wings to watch NASA TV during the Hubble repair mission’s EVAs. This is perhaps astronomy’s “championship” event, and instead of the Final Four, it’s the final Hubble servicing mission. Keel will be watching with colleagues and students to take in the EVAs and perhaps even raise a Wild Wing in salute of the astronauts achievements.
On her Starstryder blog, Gay says, “While this idea started in Tuscaloosa, there is no reason for it to end there. Many restaurants and bars have cable television packages that include NASA TV. Next week, grab a friend and grab a beverage and ask the guy behind the bar to tune the TV into the greatest high risk game of all: It’s Man versus the Machine as Mike Massimino and the STS-125 team of astronauts upgrade the Hubble Space Telescope.”
If you’re interested in joining in, check out the NASA TV schedule.
It’s Official: Hubble Mission to Launch May 11
[/caption]After today’s Flight Readiness Review for space shuttle Atlantis’ STS-125 mission to the Hubble Space Telescope, mission managers unanimously agreed to set May 11 at 2:01 p.m. EDT as the launch date. This long awaited flight will repair and upgrade Hubble, likely the most significant satellite ever launched. And, for the space shuttle, it’s a final visit to a dear, old friend.
During the 11-day mission’s five spacewalks, astronauts will install two new instruments, repair two inactive ones and perform the component replacements that will keep the telescope functioning into at least 2014.
In addition to the originally scheduled work, Atlantis also will carry a replacement Science Instrument Command and Data Handling Unit for Hubble. Astronauts will install the unit on the telescope, removing the one that stopped working on Sept. 27, 2008, delaying this servicing mission until the replacement was ready.
Veteran astronaut Scott Altman will command the final space shuttle mission to service NASA’s Hubble Space Telescope, and retired Navy Capt. Gregory C. Johnson will serve as pilot. Mission specialists rounding out the crew are: veteran spacewalkers John Grunsfeld and Mike Massimino, and first-time space fliers Andrew Feustel, Michael Good and Megan McArthur.
Source: NASA
Starbursts from Dwarf Galaxies Like Fireworks
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Fireworks in space? Astronomers are comparing “starbursts” from a galaxy that is in the throes of star formation to a Fourth of July fireworks display. And three particular galaxies are like my children’s favorite part of a fireworks display: the grand finale. These bursts occur at a fast and furious pace, lighting up a region for a short time before winking out. But that’s only part of the story. Archived data from the Hubble Space Telescope are showing that starbursts — intense regions of star formation — sweep across the whole galaxy and last 100 times longer than astronomers thought. The longer duration may affect how dwarf galaxies change over time, and therefore may shed light on galaxy evolution.
A group of astronomers studied three dwarf galaxies, NGC 4163, NGC 4068, and IC 4662. Their distances range from 8 million to 14 million light-years away. The trio is part of a survey of starbursts in 18 nearby dwarf galaxies.
“Our analysis shows that starburst activity in a dwarf galaxy happens on a global scale,” explains Kristen McQuinn of the University of Minnesota in Minneapolis and leader of the study. “There are pockets of intense star formation that propagate throughout the galaxy, like a string of firecrackers going off.” According to McQuinn, the duration of all the starburst events in a single dwarf galaxy would total 200 million to 400 million years.
These longer timescales are vastly more than the 5 million to 10 million years proposed by astronomers who have studied star formation in dwarf galaxies. “They were only looking at individual clusters and not the whole galaxy, so they assumed starbursts in galaxies lasted for a short time,” McQuinn says.
Dwarf galaxies are considered by many astronomers to be the building blocks of the large galaxies seen today, so the length of starbursts is important for understanding how galaxies evolve.
“Astronomers are really interested to find out the steps of galaxy evolution,” McQuinn says. “Exploring these smaller galaxies is important because, according to popular theory, large galaxies are created from the merger of smaller, dwarf galaxies. So understanding these smaller pieces is an important part of filling in that scenario.”
With the high resolution Hubble data, McQuinn and her team were able to pick out individual stars in the galaxies and measure their brightness and color, two important characteristics astronomers use to determine stellar ages. By determining the ages of the stars, the astronomers could reconstruct the starburst history in each galaxy.
Two of the galaxies, NGC 4068 and IC 4662, show active, brilliant starburst regions in the Hubble images. The most recent starburst in the third galaxy, NGC 4163, occurred 200 million years ago and has faded from view.
The team looked at regions of high and low densities of stars, piecing together a picture of the starbursts. The galaxies were making a few stars, when something, perhaps an encounter with another galaxy, pushed them into high star-making mode. Instead of forming eight stars every thousand years, the galaxies started making 40 stars every thousand years, which is a lot for a small galaxy, McQuinn says. The typical dwarf is 10,000 to 30,000 light-years wide. By comparison, a normal-sized galaxy such as our Milky Way is about 100,000 light-years wide.
About 300 million to 400 million years ago star formation occurred in the outer areas of the galaxies. Then it began migrating inward as explosions of massive stars triggered new star formation in adjoining regions. Starbursts are still occurring in the inner parts of NGC 4068 and IC 4662.
The total duration of starburst activity depends on many factors, including the amount of gas in a galaxy, the distribution and density of the gas, and the event that triggered the starburst. A merger or an interaction with a large galaxy, for example, could create a longer starburst event than an interaction with a smaller system.
McQuinn plans to expand her study to another larger sample of more than 20 galaxies. “Studying nearby dwarf galaxies, where we can see the stars in great detail, will help us interpret observations of galaxies in the distant universe, where starbursts were much more common because galaxies had more gas with which to make stars,” McQuinn explains.
McQuinn’s results appeared in the April 10 issue of The Astrophysical Journal.
Source: HubbleSite
Hubble Discovers a Strange Collection of White Dwarf… Dwarfs
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A collection of very odd white dwarfs have been discovered in a local globular cluster. Twenty-four white dwarfs (18 of them are new discoveries) have been spotted. Although these degenerate stars aren’t exactly an uncommon (they are the small sparkling remnants left over after star death), this particular set are unique; they are made from helium, rather than the “standard” carbon and oxygen. And they are small, even smaller than the smallest dwarfs.
How did this dense cluster of old stars evolve? It turns out their stellar material is being stolen, stifling their development…
“Helium-core white dwarfs have only about half the mass of typical white dwarfs, but they are found concentrated in the center of the cluster,” said Prof. Adrienne Cool, from San Francisco State University, in a paper to be published in the Astrophysical Journal in July. “With such low masses, the helium-core white dwarfs ought to be floating all around the cluster, according to theory. The fact that we find them only in the central regions suggests that they have heavy companions — partner stars that anchor them to the cluster center.”
Before a white dwarf emerges from a planetary nebula, the parent star will have gone through the red giant phase (a phase our Sun is expected to go through in 4-5 billion years time). If this red giant has a binary partner (which seems to be the case of the 24 white dwarfs in this study), the outer layers of the puffed-up giant will be stripped away by the partner, stifling the red giant’s evolution. As mass is lost, the giant never gets the chance to burn helium and then progressively heavier elements such as carbon and oxygen in and around its core. Helium then becomes the key component of these smaller-than-usual white dwarfs.
“This is the first time that helium-core white dwarf stars have been discovered in partnerships with other white dwarfs in a globular cluster,” Cool said. “This large sample allows us to answer questions about the mass and nature of the partner stars, and the prevalence of these kinds of binaries in the globular cluster.”
Binary stars are known to affect their partners fairly radically, they are even known to slow or even stop the development of black holes, stripping the outer layers of the dying star, stifling black hole development by removing mass from the parent star. However, not all questions have been answered.
From Cool’s calculations, 5% of the stars found in NGC 6397 should end their lives as dim helium-core white dwarf stars, but after studying Hubble data, many of these tiny dwarfs are missing. “It’s possible that these helium-core white dwarfs cool so slowly that they haven’t had time to get very faint yet,” Cool said.
There remains the possibility that the oldest binaries containing helium-core white dwarfs have actually been destroyed by interactions with other stars in the cluster. Regardless, this is a fascinating area of study. To understand how these ancient stars evolve will not only aid the development of globular cluster models, but it will provide an invaluable insight to how binary stars influence their partners.
Source: EurekAlert!
NASA Will Try to Launch Hubble Repair Mission Early
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Personally, I think this move is just in response to the Onion’s most recent dig at NASA (“NASA Embarks on Epic Delay”) but mission managers for the upcoming Hubble repair mission are considering moving the launch of space shuttle Atlantis up one day to May 11. This would allow an extra day for launch attempts. May 12 had been the target day, but deputy program manager LeRoy Cain told reporters at a press conference on Thursday that the shuttle will likely be ready a day earlier, which would give Atlantis and extra day for a launch attempt before having to stand down for a week to allow the military to proceed with a previously scheduled launch at the Eastern Test Range. A decision about whether Atlantis will be ready to fly on the 11th will come next week Thursday (April 30) following a mission management review. But an accident at the launch pad that dinged one of Atlantis’ payload bay doors might hinder moving the launch up a day, and engineers are assessing if a repair is necessary.
A one-and-one-eighth-inch socket from a torque wrench fell from a service platform and hit Atlantis’ left payload bay door radiator while cargo for the Hubble repair mission was being installed. None of the cargo for the mission was damaged. Engineers will decide if any repairs are needed.
But moving the launch up a day may be a first for NASA.
“We prefer to have three launch attempts days available and the team is off evaluating May 11,” Cain said. “It looks very good, but it will be constrained by the work that needs to be done with the cargo elements. We’ll set the official launch date next week
If any delays occur (weather, technical, etc) that Atlantis can’t get off the pad by May 13, the next opportunity to launch wouldn’t be until May 22. NASA, the military and commercial operators share tracking, safety and other support services at Cape Canaveral Air Force Station. Usually, it takes at least two days to configure the range for supporting different types of rockets.
At a later press briefing yesterday, the crew of the STS-125 mission to Hubble said they are looking forward to the mission. “We are ready for this mission, we are trained and looking forward to executing everything we’ve been preparing for,” said the commander Scott Altman.
The other “big” news revealed (perhaps another first) during the crew press conference is that Mike Massimino, who has been Twittering during the training for the mission, (@Astro_Mike) will attempt to Twitter from space. Massimino said he wasn’t yet sure how the team would work out the technical issues, as space missions don’t usually have streaming internet.
“We’re going to be really busy so I’m not sure how much we’ll do this from orbit,” he said. “I’ll try to do it when I have free time in between missions. I can’t make any promises, but I’m going to try.”