Astronomy Archives

February 27, 2009December 24, 2015 by Tammy Plotner

Weekend SkyWatcher’s Forecast: February 27 – March 1, 2009

Greetings, fellow SkyWatchers! Are you ready for the weekend? Then let’s tackle both fun and serious studies as we take on a bright open star cluster, Herschel 400 objects, lunar subjects, planets, comets and even a galaxy cluster. If you’re ready to learn more about the history behind the observing and have some fun under the stars, then just follow me…

Friday, February 27, 2009 – Today let’s celebrate the 1897 birth on this date of Bernard Lyot, master of optics. He invented the polariscope, and produced the first solar coronagraph. He also made the first motion pictures of solar prominences. Lyot was an astute observer, and realized that the lunar surface had similar properties to volcanic dust. He didn’t see canals on Mars but observed sandstorms there, as well as atmospheric conditions on other planets. The Lyot filter is well known, and so is his micrometer, a device used to make precise distance measurements, especially those between close double stars. By all accounts a wonderful and generous man, Lyot sadly died of a heart attack while returning from seeing an eclipse.

Honor Lyot’s work by studying two open clusters, found about a fist-width north of Xi Puppis. The brighter of the two – M47 (RA 07 36 36 Dec -14 29 00) – is 1,600 light-years away and a glorious object for binoculars. Filled with mixed-magnitude stars that resolve fully to aperture, M47 features the matched-magnitude double star Struve 1211 near its center. For all its bright beauty, this stellar swarm has the most ironic of histories. Probably discovered first by Hodierna but kept secret, it was independently recovered by Charles Messier, but its position was logged incorrectly. Later, it was cataloged by both William and Caroline Herschel. . .and yet again by John Herschel, who said: ‘‘This cluster has not since been observed. It is probably very loose and poor one.’’ Even Dreyer had a hard time nailing it down! Funny, considering it has only been there for 78 million years…

While M47 is a Herschel object, look just slightly north (about a field of view) to pick up another cluster that borders it, NGC 2423 (RA 07 40 45 Dec -9 09 00). This compressed cluster contains more than two dozen faint stars with a lovely golden binary at its center. By comparing the two clusters telescopically, you are also expanding your own studies by viewing two different types of stellar evolution: M47 is very similar to the Pleiades, while NGC 2423 more closely resembles the Hyades.

Saturday, February 28, 2009 – If you didn’t notice the beautiful visage of the tender young Moon and Venus last night at sunset, try again tonight. The pair will be even closer! For most observers, Venus will be only slightly more than a degree away from the Moon’s limb. Have you checked Venus’s phase in the telescope lately? Just like our own Moon, the inner planets (Mercury and Venus) have phases. Because they’re inside Earth’s orbital path, we only see a thin crescent when they first emerge from the Sun’s glare, and they become gibbous as they are about to pass behind the Sun from our point of view. That’s also the reason why we only see these two planets either after sunset or before sunrise!

Take a closer look at the slender crescent Moon. It, too, has only just emerged from the Sun’s glare, and now is the time to get a great look at two craters – Langrenus and Vendelinus. If you remember Mare Fecunditatis, you won’t have any trouble spotting Langrenus on its south shore about mid-way along the Moon’s visible limb. It’s a very old crater with an approximate diameter of 132 kilometers, and appears to binoculars as a shallow, bright ring; featuring a central peak. Further south is equally old Vendelinus. Slightly larger and spanning 147 kilometers, it will appear even more shallow – because it is. It lacks a central peak, but telescopes at high power can resolve its few minor interior craters.

Keep your binoculars or telescopes out for a while after the Moon sets, and let’s head a little less than a fist-width east-southeast of Alpha Monocerotis (RA 08 00 01 Dec -10 46 12) to check out NGC 2506. On a dark night, this nearly 7th magnitude object is one of the most impressive of the Monoceros open star clusters. Caught in a chain of stars, it displays a rich concentration, almost appearing like a globular cluster. NGC 2506 has been used to study old, metal-poor galactic clusters. Evolution has enriched its iron content, and – despite its extreme age – it is still a beauty. Be sure to mark your Hershel ‘‘400’’ notes!

Sunday, March 1, 2009 – In 1966, Venera 3 became the first craft to touch another planet when it impacted Venus on this date. Although communications failed before it could transmit data, it was still a milestone achievement. If you’re out at sunset, be sure to have a look at Venus and say “Spaseba!”

Once you’ve viewed Venus, let’s turn our observations toward tonight’s Moon and begin by identifying some prominent lunar craters around Mare Crisium that can be spotted easily with a small telescope. North you’ll spy Cleomides and at the western edge, Proclus. Near the terminator northwest is Macrobius, and southwest is Taruntius. Power up and identify the small wells of Peirce, Picard, and Lick inside the smooth sands of Crisium. Lather, rinse and repeat… The more often you repeat crater names to yourself (and aloud) the greater the chances are that you’ll retain these names in your memory. Now, let the Moon wester and we’ll go again…

In 2003, another Deep-Sky Companion book by notable observer and author Stephen O’Meara premiered. Known for his high-quality sketches of Solar System objects and uncanny observing skills, O’Meara was the first to sight Comet Halley in 1985, and sketch the dark spokes in Saturn’s rings (before Voyager had imaged them). Still part of the editorial staff at Sky & Telescope, and a treasured lecturer, let’s take just a moment to congratulate Steve on a lifetime of achievement! (folks? you will never meet a more genuinely kind person and one who treats fellow amateur astronomers with such huge respect. i have met a great many of my astronomy “heroes” over the years and steve-o is most definitely the kind of star i’d like to be some day.)

Are you ready to practice Steve’s powers of observation? Then begin with Comet Lulin – now speeding in the eastern edge of the dim constellation of Cancer. If you have difficulty finding it, look for the large, backwards question mark of the prominent asterism of Leo. The bright star you see that’s the “period” of the question mark is Regulus – and Comet Lulin is a couple of binocular fields west. Once you’ve spied it, try comparing details to what you may have observed of Lulin’s previous behavior and appearance. Is the comet moving faster than when you first began observing it? It the tail longer? Brighter? What direction does it point in? Has the coma become more diffuse or larger? Does the comet display a nucleus? Is the anti-tail still visible? Asking yourself simple questions like these will help you become a far better observer!

Now wait until Saturn has cleared the horizon murk and let’s take a close look at this fascinating planet. Look for details such as ring shadows on the planet and planet shadows on the rings. Can you see the Casinni Division? How about Saturn’s satellites? Tonight you’ll find Titan leading the way well outside to the west. To the western ring edge, you’ll see Tethys… And clustered together on the eastern ring edge are Rhea, Dione and Enceladus. You won’t need the Hubble Space Telescope to see these kinds of details – just a steady sky and around a 4″ telescope. Take your time and enjoy your studies!

Ready for some serious studies? Then let’s talk about George Abell, who was born this day in 1927. Abell was responsible for cataloging 2,712 clusters of galaxies from the Palomar sky survey, a task he completed in 1958. Using these plates, Abell proposed that the grouping of such clusters delineated the arrangement of matter in the universe. He developed the luminosity function, which shows the relationship between brightness and the number of members in each cluster, allowing you to infer the cluster’s distance. Abell also discovered planetary nebulae, and developed the theory (along with Peter Goldreich) of their evolution.

For seasoned observers, wait until the Moon has set and honor Abell by viewing one of his galaxy clusters – Abell 1367, located about a degree southwest of 93 Leonis (RA 11 44 44 Dec +19 41 59). It’s an area of challenging intrigue for a large scope – spanning a degree of sky and containing as many as two dozen small galaxies – a gemstone for the galaxy collector!

Until next week? Ask for the Moon… But keep on reaching for the stars!

This week’s awesome images are: Bernard Lyot (public image), M47 and NGC 2423 (Credit: Palomar Observatory, courtesy of Caltech), Langrenus and Vendelinus (Credit: Dave Nash), NGC 2506 (credit – Palomar Observatory, courtesy of Caltech), Crisium area (Credit: Greg Konkel), Stephen James O’Meara (Credit: Sky & Telescope), Saturn & Moons (Credit: NASA), George Abell (Credit: American Institute of Physics), Abell 1367 (Credit: Palomar Observatory, courtesy of Caltech). We thank you so much for sharing the history and mystery with us!

February 26, 2009December 24, 2015 by Nancy Atkinson

Intergalactic Dust Could Be Messing Up Observations, Calculations

Spiral galaxies seen edge-on often show dark lanes of interstellar dust blocking light from the galaxy's stars, as in this image of the galaxy NGC 4565 from the Sloan Digital Sky Survey (SDSS-II).

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“Just like household dust, cosmic dust can be a nuisance,” said astronomer Ryan Scranton of the University of California, Davis. Scranton is part of a team of researchers from the Sloan Digital Sky Survey that have been analyzing the colors of distant quasars whose light passes in the vicinity of foreground galaxies on its way to the Earth. What they found is that the vast expanses of intergalactic space appear to be filled with a haze of tiny, smoke-like “dust” particles that dim the light from distant objects and subtly change their colors. “Galaxies contain lots of dust, most of it formed in the outer regions of dying stars,” said team leader Brice Ménard of the Canadian Institute for Theoretical Astrophysics. “The surprise is that we are seeing dust hundreds of thousands of light-years outside of the galaxies, in intergalactic space.”

An implication of this finding means that since most distant supernovae are seen through some haze, our current estimates of their distances may be affected.

Dust grains block blue light more effectively than red light. “We see this when the sun sets: light rays pass through a thicker layer of the atmosphere,” said Scranton, “absorbing more and more blue light, causing the sun to appear reddened. We find similar reddening of quasars from intergalactic dust, and this reddening extends up to ten times beyond the apparent edges of the galaxies themselves.”

The team analyzed the colors of about 100,000 distant quasars located behind 20 million galaxies, using images from SDSS-II. “Putting together and analyzing this huge dataset required cutting-edge ideas from computer science and statistics,” said team member Gordon Richards of Drexel University. “Averaging over so many objects allowed us to measure an effect that is much too small to see in any individual quasar.”

Supernova explosions and “winds” from massive stars drive gas out of some galaxies, Ménard explained, and this gas may carry dust with it. Alternatively, the dust may be pushed directly by starlight.

“Our findings now provide a reference point for theoretical studies,” said Ménard.

Intergalactic dust could also affect planned cosmological experiments that use supernovae to investigate the nature of “dark energy,” a mysterious cosmic component responsible for the acceleration of the expansion of the universe.

Intergalactic dust doesn’t remove the need for dark energy to explain current supernova data, Ménard explained, but it may complicate the interpretation of future high-precision distance measurements. “These experiments are very ambitious in their goals,” said Ménard, “and subtle effects matter.”

The new findings are reported in a paper titled “Measuring the galaxy-mass and galaxy-dust correlations through magnification and reddening,” submitted to the journal Monthly Notices of the Royal Astronomical Society, and posted today on the web site arXiv.org.

Source: Sloan Digital Sky Survey

February 26, 2009December 24, 2015 by Nancy Atkinson

New Issue of Space Lifestyle Magazine Now Available

Have you heard about Space Lifestyle Magazine? It’s a digital magazine, with a full color layout just like a print magazine, but its all online. And the winter issue of Space Lifestyle Magazine is now online and available for free. SLM has feature articles about all aspects of space — NewSpace, NASA, military, science and astronomy — but mostly it’s about the people that make the space sector tick.

In the latest issue, you’ll find a bang-up article written by UT’s Ian O’Neill about SpaceX. Ian actually toured the SpaceX facility and took some great pictures and wrote a very comprehensive article about SpaceX’s recent successful launch to orbit. Other features include an interesting overview about the work being done to create magnetic shielding for spacecraft that will help repel radiation.

There’s also a feature story about South Korea’s Yecheon Astro Space Center selecting XCOR Aerospace services – specifically their Lynx Mark II suborbital vehicle – as its preferred supplier of suborbital space launch services.

There’s also a comprehensive rundown of the X PRIZE Lunar Lander Challenge competition last fall, and much more including book reviews (Death From the Sky by Phil Plait) and a special discount for the National Space Symposium to be held March 30-April 2 in Colorado Springs, Colorado. If you haven’t already “subscribed” to SLM, please do so for the chance to win a Zero-G parabolic flight and other prizes. Enjoy!

Check out Space Lifestyle Magazine.

February 25, 2009December 24, 2015 by Anne Minard

Jupiter, Saturn Plowed Through Asteroids, Study Says

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When Mars and Jupiter migrated to their present orbits around 4 billion years ago, they left scars in the asteroids belt that are still visible today.

The evidence is unveiled in a new paper in this week’s issue of the journal Nature, by planetary scientists David Minton and Renu Malhotra from the University of Arizona in Tucson.

The asteroid belt has long been known to harbor gaps, called Kirkwood gaps, in distinct locations. Some of these gaps correspond to unstable zones, where the modern-day gravitational influence of Jupiter and Saturn eject asteroids. But for the first time, Minton and Malhotra have noticed that some clearings don’t fit the bill.

“What we found was that many regions are depleted in asteroids relative to other regions, not just in the previously known Kirkwood gaps that are explained by the current planetary orbits,” Minton wrote in an email. In an editorial accompanying the paper, author Kevin Walsh added, “Qualitatively, it looks as if a snow plough were driven through the main asteroid belt, kicking out asteroids along the way and slowing to a stop at the inner edge of the belt.”

Walsh hails from the Observatoire de la Côte d’Azur in France. In his News and Views piece, he explains that the known Kirkwood gaps, discovered by Daniel Kirkwood in 1867, “correspond to the location of orbital resonances with Jupiter — that is, of orbits whose periods are integer ratios of Jupiter’s orbital period.” For example, if an asteroid orbited the Sun three times for every time Jupiter did, it would be in a 3:1 orbital resonance with the planet, he wrote. Objects in resonance with a giant planet have inherently unstable orbits, and are likely to be ejected from the solar system. When planets migrated, astronomers believe objects in resonance with them also shifted, affecting different parts of the asteroid belt at different times.

“Thus, if nothing has completely reshaped the asteroid belt since the planets settled into their current orbits, signatures of past planetary orbital migration may still remain,” Walsh wrote. And that’s exactly what Minton and Malhotra sought.

The asteroid belt easily gave up its secrets, showing the lingering evidence of planetary billiards on the inner edge of the asteroid belt and at the outer edge of each Kirkwood gap. The new finding, based on computer models, lends additional support to the theory that the giant planets — Jupiter, Saturn, Uranus and Neptune — formed twice as close to the sun as they are now and in a tighter configuration, and moved slowly outward.

“The orbit of Pluto and other Kuiper belt objects that are trapped in [orbits that resonate] with Neptune can be explained by the outward migration of Neptune,” Minton and Malhotra write in the new study. “The exchange of angular momentum between planetesimals and the four giant planets caused the orbital migration of the giant planets until the outer planetesimal disk was depleted.” Planetesimals are rocky and icy objects left over from planet formation.

“As Jupiter and Saturn migrated,” the authors continue, they wreaked havoc on the young asteroid belt, “exciting asteroids into terrestrial planet-crossing orbits, thereby greatly depleting the asteroid belt population and perhaps also causing a late heavy bombardment in the inner Solar System.”

The late heavy bombardment is proposed to have occurred about 3.9 billion years ago, or 600 million years after the birth of the Solar System, and it’s believed to account for many of the Moon’s oldest craters. Walsh said a reasonable next step, to corroborate the theory about the newly described clearings in the asteroid belt, is to link them chronologically with the bombardment.

LEAD PHOTO CAPTION: Artist’s depiction of the asteroid belt between Mars and Jupiter. Credit: David Minton and Renu Malhotra

Source: Nature

February 25, 2009December 24, 2015 by Anne Minard

Penetrating New View Into The Helix Nebula

The blue-green glow in the centre of the Helix comes from oxygen atoms shining under effects of the intense ultraviolet radiation of the 120 000 degree Celsius central star and the hot gas. Further out from the star and beyond the ring of knots, the red colour from hydrogen and nitrogen is more prominent. Cerdit: Max-Planck Society/ESO telescope at the La Silla observatory in Chile

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ESO’s La Silla Observatory has snapped a new image of the famous Helix planetary nebula, revealing a rich — and rarely photographed — background of distant galaxies.

The Helix Nebula, NGC 7293, about 700 light-years away in the constellation of Aquarius, is a Sun-like star in its final explosion before retirement as a white dwarf.

Shells of gas are blown off from the surface of such stars, often in intricate and beautiful patterns, and shine under the harsh ultraviolet radiation from the faint, hot central star. The main ring of the Helix Nebula is about two light-years across, or half the distance between the Sun and its nearest stellar neighbour.

Despite being photographically spectacular, the Helix is hard to see visually as its light is thinly spread over a large area of sky. The history of its discovery is rather obscure. It first appears in a list of new objects compiled by the German astronomer Karl Ludwig Harding in 1824. The name Helix comes from the rough corkscrew shape seen in the earlier photographs.

Although the Helix looks very much like a doughnut, studies have shown that it possibly consists of at least two separate discs with outer rings and filaments. The brighter inner disc seems to be expanding at about 100,000 km/h (about 62,000 miles/h) and to have taken about 12,000 years to form.

Because the Helix is relatively close — it covers an area of the sky about a quarter of the full Moon — it can be studied in much greater detail than most other planetary nebulae and has been found to have an unexpected and complex structure. All around the inside of the ring are small blobs, known as “cometary knots,” with faint tails extending away from the central star. Although they look tiny, each knot is about as large as our Solar System. These knots have been extensively studied, both with the ESO Very Large Telescope and with the NASA/ESA Hubble Space Telescope, but remain only partially understood. A careful look at the central part of this object reveals not only the knots, but also many remote galaxies seen right through the thinly spread glowing gas. Some of these seem to be gathered in separate galaxy groups scattered over various parts of the image.

For a sweet treat, throw a little of this into your coffee: Helix Nebula pan and zoom (video)

LEAD IMAGE CAPTION: The blue-green glow in the center of the Helix comes from oxygen atoms shining under effects of the intense ultraviolet radiation of the 120,000 degree Celsius (about 216,000 degrees F) central star and the hot gas. Further out from the star and beyond the ring of knots, the red color from hydrogen and nitrogen is more prominent. Credit: Max-Planck Society/ESO telescope at the La Silla observatory in Chile

Source: ESO

February 21, 2009December 24, 2015 by Anne Minard

Arizona Scientist: We Could All Be Martians

Artist's conception of an fragment as it blasts off from Mars. Boulder-sized planetary fragments could be a mechanism that carried life between Mars and Earth, UA planetary scientist Jay Melosh says. (Credit: The Planetary Society)

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As long as we’re still pondering human origins, we may as well entertain the idea that our ancestor microbes came from Mars.

And Jay Melosh, a planetary scientist from the University of Arizona in Tucson, is ready with a geologically plausible explanation.

Meteorites.

“Biological exchange between the planets of our solar system seem not only possible, but inevitable,” because of meteorite exchanges between the planets, Melosh said. “Life could have originated on the planet Mars and then traveled to Earth.”

jay_melosh — Jay Melosh. Credit: Maria Schuchardt, University of Arizona Lunar and Planetary Lab

Melosh is a long-time researcher who says he’s studied “geological violence in all its forms.” He helped forge the giant impact theory of the moon’s formation, and helped advance the theory that an impact led to the extinction of the dinosaurs 65 million years ago.

He points out that Martian meteorites have been routinely pummeling Earth for billions of years, which would have opened the door for past Mars microbes to hitch a ride. Less regularly, Earth has undergone impacts that sent terrestrial materials flying, and some of those could have carried microbes toward the Red Planet.

“The mechanism by which large impacts on Mars can launch boulder-sized surface rocks into space is now clear,” he said. He explained that a shock wave spreads away from an impact site faster than the speed of sound, interacting with the planetary surface in a way that allows material to be cast off – at relatively low pressure, but high speed.

“Lightly damaged material at very high speeds,” he said, “is the kind of environment where microorganisms can survive.”

Scientists have recent evidence of Earth microbes surviving a few years in space. When the Apollo 12 astronauts landed on the moon, they retrieved a camera from Surveyor 3, an unmanned lander that had touched down nearly three years prior. Earthly microbes – including those associated with the common cold — were still living inside the camera box.

“The records were good enough to show one of the technicians had a cold when he was working on it,” he said.

Scientists also have evidence that microbes can survive for thousands or even hundreds of thousands of years when frozen on Earth, but surviving that long in space would be an entirely different matter, with the bombardment of UV light and cosmic rays. Then again, the microbe Dienococcus radiodurans is known to survive in the cores of nuclear reactors.

Melosh acknowledges that scientists lack proof that such an exchange has actually occurred between Mars and Earth — but science is getting ever closer to being able to track it down.

LEAD PHOTO CAPTION: Artist’s conception of an fragment as it blasts off from Mars. Boulder-sized planetary fragments could be a mechanism that carried life between Mars and Earth, UA planetary scientist Jay Melosh says. (Painting by Don Davis. Copyright SETI Institute, 1994)

Source: University of Arizona and an interview with Jay Melosh

February 21, 2009December 24, 2015 by Tammy Plotner

Tunnel Vision – Step Into the “Ring”…

M7n Parallel Vision by Jukka Metsavainio

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Who doesn’t recognize this awesome image of Messier Object 57 which was taken by the Hubble Space Telescope? The original color image was assembled from three black-and-white photos taken through different color filters with the Hubble’s Wide Field Planetary Camera 2. We know the blue filtration isolates emission from very hot helium, which is located primarily close to the hot central star… just as green represents the further away ionized oxygen and cool red shows ionized nitrogen gas at the farthest position of all. We know where they’re supposed to be, but we’ve never quite seen it in dimension until it’s been visualized by the “magic” of Jukka Metsavainio…

Like all our our “stereo” image produced for UT by Jukka Metsavainio, two versions are presented here. The one above is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. I have heard from a friend recently that if you place a card in the center of the image with the edge towards you, it aids in seeing the parallel version. (And he was right.) The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. (The card “trick” also works well here, too!) Jukka’s visualizations of what Hubble images would look like if we were able to see them in dimension come from studying the object, its known field star distances and the different wavelengths of light. Are you ready to “cross” the boundary and step into the “Ring” for another round with Messier 57? Then let’s rock…

Originally discovered by discovered by Antoine Darquier de Pellepoix in January, 1779 and independently found by Charles Messier later that same month, it was Darquier who first said that it was “…as large as Jupiter and resembles a planet which is fading.” Thanks to his description, the term ” planetary nebula” stuck because of their similarity in appearance to giant planets when viewed through small optical telescopes. However, Sir William Herschel wasn’t quite so aperture limited, and he was the first to propose this new object was a nebula was formed by multiple faint stars. By 1800, Count Friedrich von Hahn had discovered M57’s central star and within 64 years William Huggins was studying its spectral signature. Just a blink of a cosmic eye later, another 22 years, Hungarian astronomer Jen? Gothard had discovered it had a planetary nebula nucleus.

What has remained constant over the years is the classic bipolar structure associated with the “Ring” nebula – a prolate spheroid with strong concentrations of material along its equator. Its symmetrical structure is one of the best known in the night sky – right down to the knots along the edges that can often be observed with larger telescopes. What exactly are they? According to C.R. O’Dell (et al); ” The equator of the Ring Nebula is optically thick and much denser than the optically thin poles. The inner halo surrounding NGC 6720 represents the pole-on projection of the AGB wind at high latitudes (circumpolar) directly ionized by the central star, whereas the outer, fainter, and circular halo is the projection of the recombining AGB wind at mean to low latitudes, shadowed by the main nebula. The spatio-kinematical properties of the Ring Nebula and the origin of the dense knots commonly observed in late-stage planetary nebulae are critically compared with the predictions of radiation-hydrodynamic and wind interaction models.”

These winds, bubbles and explosions were part of the original Hubble photograph where our visualization came from. “We have studied the closest bright planetary nebulae with the Hubble Space Telescope’s WFPC2 in order to characterize the dense knots already known to exist in NGC 7293.” says O’Dell, “We find knots in all of the objects, arguing that knots are common, simply not always observed because of distance. The knots appear to form early in the life cycle of the nebula, probably being formed by an instability mechanism operating at the nebula’s ionization front. As the front passes through the knots they are exposed to the photoionizing radiation field of the central star, causing them to be modified in their appearance. This would then explain as evolution the difference of appearance like the lacy filaments seen only in extinction in IC 4406 on the one extreme and the highly symmetric “cometary” knots seen in NGC 7293. The intermediate form knots seen in NGC 2392, NGC 6720, and NGC 6853 would then represent intermediate phases of this evolution.”

Anyone who is willing to step into the ring with this champion of all planetary nebulae is liable to end up with a few knots somewhere! Enjoy your tunnel vision journey….

February 21, 2009December 24, 2015 by Anne Minard

NASA Delays Discovery Launch Fourth Time

The space shuttle Discovery moved to the Kennedy Space Center Launch Pad on Jan. 14, but launch has been postponed until further notice. Credit: NASA/Troy Cryder

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NASA announced yet another delay for the launch of the Discovery STS-119 mission to the International Space Station Friday, marking the fourth time the mission has been postponed.

An all-day review of the craft’s readiness for launch left managers still under-confident about the operations of three hydrogen control valves that channel gaseous hydrogen from the main engines to the external fuel tank. Engineering teams have been working to identify what caused damage to a flow control valve on shuttle Endeavour during its November 2008 flight. NASA managers decided Friday more data and possible testing are required before launch can proceed.

“We need to complete more work to have a better understanding before flying,” said Bill Gerstenmaier, associate administrator for Space Operations at NASA Headquarters in Washington. Gerstenmaier chaired Friday’s Flight Readiness Review.

“We were not driven by schedule pressure and did the right thing. When we fly, we want to do so with full confidence.”

306355main_hatch-m_800-600 — The STS-119 crew members gather in front of the hatch into space shuttle Discovery to place the mission plaque. Standing from left are Mission Specialists Joseph Acaba, Koichi Wakata, Steve Swanson, John Phillips and Richard Arnold and Pilot Tony Antonelli. Kneeling in front is Commander Lee Archambault. Photo credit: NASA/Kim Shiflett January 20, 2009

Besides understanding what happened with Endeavor’s valves last fall, teams also have tried to determine the consequences if a valve piece were to break off and strike part of the shuttle and external fuel tank.

Meanwhile, the Discovery launch date has shifted from Feb. 12, to Feb. 19, to Feb. 22, Feb. 27 and now — as of last night’s briefing — is postponed until further notice. The Space Shuttle Program has been asked to develop a plan for further inspections. The plan will be reviewed during a meeting on Wednesday, Feb. 25 and a new target launch date may be considered then.

The STS-119 mission is supposed to enhance the solar gathering power of the International Space Station so it might support a larger crew. When it does fly, STS-119 will tote two solar array wings, each of which has two 115-foot-long arrays, for a total wing span of 240 feet, including the equipment that connects the two halves and allows them to twist as they track the sun. Altogether, the four sets of arrays can generate 84 to 120 kilowatts of electricity – enough to provide power for more than 40 average homes.

The mission astronauts arrived at the Kennedy Space Center Jan. 19 and have more or less been in standby mode ever since, shuttling back and forth between Florida and the Johnson Space Center in Houston. On Wednesday of this week, STS-119 mission specialists Richard Arnold and Joseph Acaba were in the Neutral Buoyancy Laboratory at Johnson, brushing up on spacewalk procedures. As of Thursday, the astronauts were in launch-countdown mode which included preflight quarantine.

February 20, 2009December 24, 2015 by Tammy Plotner

GLOBE at Night 2009 – Can You See the Stars?

Turning out the lights for “Earth Hour” is going to be a great way to demonstrate caring about climate changes by turning off the lights – but what about the impact that light pollution has on our skies? 2008 marked a monumental shift in human history when the number of people living in cities exceeded half the people on Earth. Because of the ambient light of urban landscapes, many city dwellers have never seen a sky full of stars. Are you interested in helping science study the impact of lighting in your area? Then step inside and learn more about GLOBE…

GLOBE at Night is a wonderful way for everyone around the world to participate as a citizen-sciencist to raise public awareness of the impact of artificial lighting on local environments. This event encourages everyone – students, educators, dark sky advocates and the general public – to measure the darkness of their local skies and contribute their observations online to a world map. GLOBE at Night is a centerpiece of the Dark Skies Awareness Global Cornerstone Project for the International Year of Astronomy (IYA) in 2009, and we need people – just like you – to get involved! Data collection and online reporting is simple and user-friendly.

Led by the educational outreach staff at the National Optical Astronomy Observatory and the University Corporation for Atmospheric Research GLOBE Program, the GLOBE at Night campaign will take place for a 4th year from March 16-28, 2009. “The geographic reach of the GLOBE at Night program exceeded our wildest expectations,” said Connie Walker, an astronomer and science education specialist at the National Optical Astronomy Observatory (NOAO), one of the event’s major co-sponsors. “We fell a few hundred short of our target of 5,000 total observations, but the engagement and excitement of large family groups, and dozens of school children participating in the activity together, more than make up for a few less data points.”

Over the past 3 years, tens of thousands of citizen-scientists around the world have contributed measurements of their local sky brightness to a growing global database in two ways: simple unaided-eye observations toward the constellation Orion and quantative digital measurements through a handheld, well-calibrated sky-brightness meter. For the first method, citizen-scientists take data on light pollution levels by comparing what they see toward Orion, with star maps showing different stellar brightness limits. The basic idea is to look for the faintest stars and match them to one of seven star maps of progressively fainter limiting magnitudes. For the second method, digital sky-brightness meters are used for more precise measurements. The low-cost digital Sky Quality Meters (SQMs), manufactured by Unihedron, can make a highly repeatable, direct measurement of integrated sky brightness. The newly available second-generation of SQM-Ls being used this year by several GLOBE at Night sites has a cone-shaped “field of view” that is three times more narrow than the older model. This specifically aids its use in city environments, where surrounding lights or buildings may affect the readings.

To learn the five easy steps to participate in either type of GLOBE at Night program and to obtain important information on light pollution, stellar magnitudes, the mythology of Orion, how to find Orion, how to obtain your latitude and longitude, and how to use an SQM, see the GLOBE at Night website. No prior experience is necessary and all the information you need to participate is right there – along with downloads for activity kits for families, teachers and invididuals in six different languages. All observations will be available online via Google Earth and as downloadable datasets, too.

Thanks to an international network of partners, GLOBE reaches people around the world, and during their first two years managed 20,000 observations from a total of 100 countries. This year, they’re hoping for an even greater success rate and within weeks of submitting your data, a world map showing the results of your studies will be made available. Using this information, you can then compare the data to previous studies, as well as satellite data and population density data. Collecting information from mulitple locations inside a single city or region is highly encourged, and would make a great class project or astronomy club activity!

By activity participating in projects like GLOBE, you can make difference. More measurements made each year and over the next few years will allow for in more depth analysis. More measurements within a city will provide maps of higher resolution and comparisons between years would allow people to monitor changes. Just like our other Earthly environments, monitoring our lighting environment will allow us as citizen-scientists to identify and preserve dark sky locations in cities or catch an area developing too quickly and influence people to make smart choices in lighting by providing them with informed neighbors. As just everyday, ordinary people, we can impact what happens by educating ourselves and others. If more and more people took a few minutes during the March 2009 campaign to measure sky brightness either toward Orion with the unaided-eye or toward zenith with a Sky Quality Meter (or both!), their measurements – and yours – will make a world of difference!

Many thanks to NOAO team members, Constance E. Walker, Douglas Isbell, Stephen M. Pompea, David A. Smith and Thomas R. Baker.

February 20, 2009December 24, 2015 by Anne Minard

Sweet Potatoes Flew into Space Aboard Columbia

Sweet potato cuttings grown in an Alabama laboratory were flown aboard Columbia to test root growth in microgravity. Courtesy of NASA.

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A team of researchers from the Deep South sent sweet potato plants into space, as part of an experiment aimed at providing food for long-term space missions.

Desmond G. Mortley, from the G.W. Carver Agricultural Experiment Station at Alabama’s Tuskegee University, and his colleagues launched the sweet potato cuttings on a five-day mission aboard the space shuttle Columbia, and compared their success to ground-based cuttings at Kennedy Space Center in Florida.

“The intent of the experiment was to study if stem cuttings would be a successful means of propagating plants in space, just as they are on Earth,” said Raymond Wheeler, a study co-author from NASA’s Biological Science Office at the Kennedy Space Center. “The results showed that the cuttings did indeed produce adventitious roots in microgravity, suggesting that cuttings should work well in space settings.”

The sweet potato experiment was flown on Columbia’s July 1999 mission to the Chandra X-Ray Observatory. The study findings were published in the May 2008 issue of the Journal of American Society for Horticultural Science, although a public press release was issued just this week.

Seeds of several crops have been grown in microgravity, but this was the first test for plants grown from cuttings. Cuttings grow roots faster than seeds do, and sweet potato cuttings regenerate very easily. This made them ideal for the study.

According to the study authors, all of the cuttings produced roots and growth was “quite vigorous in both ground-based and flight samples.” Except for a slight browning of some root tips in the flight samples, all of the stem cuttings appeared normal, they added. The roots on the flight cuttings tended to grow in random directions, sometimes perpendicular to the stems. Also, stem cuttings grown in microgravity had more roots and longer roots than ground-based controls.

The next step, Mortley and his colleagues say, will be to experiment over longer space missions to test root cuttings’ ability to grow plants.

Source: Eurekalert and Journal of American Society for Horticultural Science.