Posted on by Fraser Cain

Searching for Moons Around Distant Planets

Image credit: ESA

The European Space Agency is working on a new mission that could be able to detect moons orbiting planets in other star systems. In 2008, the ESA will launch Eddington, which will detect the drop in light as planets as small as Mars pass in front of their parent stars. Astronomers should theoretically be able to detect moons going around those planets because of their gravity – if the planet dims the star a few minutes earlier or later than expected, it will have one or more moons.

ESA is now planning a mission that can detect moons around planets outside our Solar System, those orbiting other stars.

Everyone knows our Moon: lovers stare at it, wolves howl at it, and ESA recently sent SMART-1 to study it. But there are over a hundred other moons in our Solar System, each a world in its own right.

A moon is a natural body that travels around a planet. Moons are a by-product of planetary formation and can range in size from small asteroid-sized bodies of a few kilometres in diameter to several thousand kilometres, larger even than the planets Mercury and Pluto.

Landing on another moon
One such large moon is Titan, the target for ESA?s daring Huygens mission that in 2005 will become the first spacecraft ever to land on a moon of another planet. Titan is slightly bigger than the planet Mercury, and is only called a moon because it orbits the giant planet Saturn rather than the Sun.

Four other large moons can be found around another of our neighbours, Jupiter. These are Io, Europa, Ganymede and Callisto. Europa has captured attention because beneath its icy surface, scientists think that an ocean covers the entire moon. Some scientists have even speculated that microscopic life might be found in that ocean.

Habitable moons?
In 2008, ESA plans to launch its ?rocky planet? finder Eddington. By detecting the drop in light seen when a world passes in front of its parent star, Eddington will be capable of discovering planets the size of Jupiter, and also those smaller than Mars.

That means, if our own Solar System is anything to go by, it will be capable of detecting moons similar in size to Titan and the four large moons of Jupiter.

It would be particularly exciting if such combinations of planets and moons were found orbiting a star at Earth?s distance from the Sun. Perhaps then the surfaces of the moons would be warmed to habitable levels.

Orbital dancing
What about moons similar to our own? An equivalent of Earth?s moon would be too small to be detected directly by Eddington, but such a body would affect the way its planet moves and it is that movement which Eddington could detect.

The Earth and the Moon orbit the Sun like ballroom dancers who move around the floor, simultaneously twirling about one another. This means the Earth does not follow a strictly circular path through space, sometimes it will be leading the Moon and sometimes trailing.

This causes variations of up to five minutes from where the Earth would be if it did not possess a moon. By precisely timing when a rocky planet passes in front of its star, Eddington will be able to show if a moon is pulling its planet out of a strictly circular path around the star.

So, how many moons can Eddington expect to find circling planets around other stars? If we make an estimate based on our own Solar System, several thousands will be found ? however, no one knows for sure. That?s what makes the quest so exciting!

Original Source: ESA News Release

Posted on by Fraser Cain

Keck Uses Adaptive Optics for the First Time

Image credit:: Keck

The 10-metre Keck II observatory took an important step forward recently when it began observations with its new adaptive optics system. The system uses a laser to create a fake star about 90 kilometres up in the sky – a computer can then use this to calculate how to remove the effect of atmospheric disturbances. Adaptive optics have been used on smaller telescopes, but this is the first time it’s been employed on a telescope as large as the mighty Keck II; it took nine years to adapt the observatory.

A major milestone in astronomical history took place recently at the W.M. Keck Observatory when scientists, for the first time, used a laser to create an artificial guide star on the Keck II 10-meter telescope to correct the blurring of a star with adaptive optics (AO). Laser guide stars have been used on smaller telescopes, but this is their first successful use on the current generation of the world’s largest telescopes. The resulting image (Figure 1), captured by the NIRC2 infrared camera, was the first demonstration of a laser guide star adaptive optics (LGS AO) system on a large telescope. When complete, the LGS AO system will mark a new era of astronomy in which astronomers will be able to see virtually any object in the sky with the clarity of adaptive optics.

“This is one of the most gratifying moments in all my years at Keck,” remarked Dr. Frederic Chaffee, director of the W.M. Keck Observatory the evening the observations were made. “Like any positive first light result, there is much to be done before the system can be considered operational. But also like any positive first light result, it shows that it can be done, and gives us great optimism that our goals are not impossible dreams, but are instead attainable realities.”

Adaptive optics is a technique that has revolutionized ground-based astronomy through its ability to remove the blurring of starlight caused by the earth?s atmosphere. Its requirement of a relatively bright “guide star” in the same field of view as the scientific object of study has generally limited the use of AO to about one percent of the objects in the sky.

To overcome this restriction, in 1994 the W.M. Keck Observatory began working with Lawrence Livermore National Labs (LLNL) to develop an artificial guide star system. By using a laser to create a ?virtual star,? astronomers can study any object in the vicinity of much fainter (up to 19th magnitude) objects with adaptive optics and reduce its dependence on bright, naturally occurring guide stars. Doing so will increase sky coverage for the Keck adaptive optics system from an estimated one percent of all objects in the sky, to more than 80 percent.

“This new capability of using a laser guide star with a large telescope has invited astronomers to start exploring the night sky in a much more comprehensive manner,” said Adam Contos, optics engineer at the W.M. Keck Observatory. “In the future, I would expect most major observatories to be installing similar systems to take advantage of this incredible enhancement to their AO capabilities.”

In January 2001, after more than seven years in development, the Keck and LLNL teams celebrated the completion of the Keck laser guide star system. The artificial star results when light from a 15-watt dye laser causes a naturally occurring layer of sodium atoms to glow about 90 km (56 miles) above the earth’s surface. It would take another two years of sophisticated research and design before the laser system could be integrated into the Keck II adaptive optics system.

In the early morning hours of September 20th, all subsystems finally came together to reveal the unique capability of the Keck LGS AO system and its potential to resolve extremely faint objects. The system locked on a 15th magnitude star, a member of a well-known T Tauri binary called HK Tau and revealed details of the circumstellar disk of the companion star. It was the first time an adaptive optics system on a very large telescope had ever used an artificial guide star to resolve a faint object.

A key challenge the LGS AO team faced was how successful the efforts would be to integrate and achieve good performance measurements for each required sub-system. Concerns about the power of the laser and its spot quality, operation of the laser traffic control system, the ability of the new sensors to lock on fainter guide stars, and being able to optimize the image quality through an accurate understanding of the aberrations that could not be measured by using the laser guide star, were all factored into the evening’s observing.

“First light was a superb team effort,” said Dr. Peter Wizinowich, team leader for the adaptive optics team at W.M. Keck Observatory. “It was very satisfying to have each of the many subsystems perform so well on our first attempt. To quote Virgil, ‘Audentes Fortuna Juvat,’ fortune favors the bold.”

The quality of the LGS AO first light images was extremely high. While locked on a 14th magnitude star, the Keck LGS AO system recorded “Strehl ratios” of 36 percent (at 2.1 micron wavelength, 30-second exposure time, Figure 3), compared to four percent for uncorrected images. Strehl ratios measure the degree to which an optical system approaches “diffraction-limited” perfection, or the theoretical performance limit, of the telescope.

Another performance metric, the “full width at half maximum” (FWHM), for this 14th magnitude star was 50 milli-arcseconds, compared to 183 milli-arcseconds for the uncorrected image. FWHM measurements help astronomers determine the actual edges of an object, where the detection may be imprecise or difficult to determine. The measurement of 50 milli-arcseconds is about equivalent to being able to distinguish a pair of car headlights in New York while standing in Los Angeles.

Throughout the evening, the laser guide star held steady and bright, shining at an approximate magnitude of 9.5, about 25 times fainter than what the human eye can see, but ideal for the Keck adaptive optics system to measure and correct for atmospheric distortions.

Additional work is underway before the Keck LGS AO system can be considered fully operational. The Keck LGS AO system will be available for limited shared risk science next year, with full deployment to the Keck user community in 2005.

“Even with just this first test, astronomers are already clamoring to use the laser guide star system to study distant galaxies with an unprecedented resolution and power,” said Dr. David Le Mignant, adaptive optics instrument scientist at the W.M. Keck Observatory, California Association for Research in Astronomy. “By next year, adaptive optics will be used to study the rich formation history of early galaxies.”

The importance of this breakthrough to worldwide astronomy was summed up by Dr. Matt Mountain, the director of the Gemini Observatory, which operates twin 8-meter telescopes, one on Mauna Kea and one on Cerro Pachon in Chile: “This is a critical milestone for all ground-based astronomy, not just for our current generation of eight to 10-meter class telescopes, but also for our dreams of 30-meter telescopes.”

Team members responsible for the Keck LGS AO system are Antonin Bouchez, Jason Chin, Adam Contos, Scott Hartman, Erik Johansson, Robert Lafon, David Le Mignant, Chris Neyman, Paul Stomski, Doug Summers, Marcos van Dam, and Peter Wizinowich, all from the W.M. Keck Observatory, California Association for Research in Astronomy. The team gave special thanks to their collaborators at LLNL: Dee Pennington, Curtis Brown and Pam Danforth.

The laser guide star adaptive optics system was funded by the W.M. Keck Foundation.

The W.M. Keck Observatory is operated by the California Association for Research in Astronomy, a scientific partnership of the California Institute of Technology.

Original Source: Keck News Release

Posted on by Fraser Cain

More Chinese Launch Plans Emerging

News reports in China have stated that the Chinese are will attempt to join the nations capable of sending humans into space on October 15, a day after the meeting of Communist party members. The Shenzhou 5 spacecraft will carry a single astronaut (or yuhangyuan) into space for a single 90-minute loop around the Earth. It appears the Chinese are going to be very conservative on their first launch attempt, essentially matching the flight that Yuri Gagarin made more than 40 years ago. There hasn’t been an official launch announcement from the government yet.

Posted on by Fraser Cain

Book Review: Hubble: The Mirror on the Universe

“Hubble: The Mirror on the Universe” by Robin Kerrod is the newest coffee table book filled with beautiful pictures from the Hubble Space Telescope. The 192-page hardcover contains hundreds of pictures, of objects as near as our solar system to the very edges of the Universe.

The book is categorized into different kinds of astronomical objects, so the chapters go like: Stars in the Firmament, Stellar Death and Destruction, etc. Each chapter is broken up into a collection of images from Hubble that relate to the topic, and then a nice description of what’s going on in the picture. Robin Kerrod is an accomplished astronomy writer (The Sky at Night, History of NASA, more) and it really helps to have a knowledgeable guide take you through the pictures. There are also plenty of full page, and even two-page spreads dedicated to some of the best pictures from Hubble.

The book was only published in September 2003, so its big advantage to all the other Hubble coffee table books is that it’s got the newest photos. I noticed some pictures that were only released a few months ago.

What surprised me when I read the book is that it’s really an overview of astronomy, using pictures from Hubble as a background to the descriptions. Instead of ignoring things that Hubble hasn’t taken pictures of, Kerrod included pictures from other sources other than Hubble – I think this was a wise move because it makes the book a more complete view of space and astronomy than a narrow view through the Hubble mirror.

The pictures are beautiful, no argument here – you’ll recognize many of them. And the text is comprehensive and well-written. There’s really good background information on the observatory itself; how it was built, launched, repaired and upgraded.

Although it was great to see additional text and pictures to make the book a more complete view of astronomy, the non-Hubble pictures aren’t clearly marked. Sometimes there’s a mention in the image caption, and there are image credits at the back of the book, but it would have been helpful if they stated it clearly beside the images. So, you can’t assume that every picture you’re looking at was actually taken by Hubble.

Here’s a link to more information from Amazon.com – Amazon.ca – Amazon.co.uk

Posted on by Fraser Cain

Pengiuns Get a Boost from Plankton Blooms

Image credit: NASA

NASA satellite data has been used to analyze the biology of open area “hotspots” around the coast of Antarctica. The research has found that penguin populations are healthy when there are patches of open water nearby where plankton blooms can form in the sunlight. The plankton feeds shrimp-like krill which supports many other marine animals including penguins. The data was gathered by NASA’s Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and NOAA’s Advanced Very High Resolution Radiometer (AVHRR) which kept weekly records of ocean temperature and plankton levels.

NASA satellite data was used for the first time to analyze the biology of hot spots along the coast of Antarctica. The biological oases are open waters, called polynyas, where blooming plankton support the local food chain.

The research found a strong association between the well being of Adelie Penguin populations in the Antarctic and the productivity of plankton in the polynyas. Polynyas are areas of open water or reduced ice cover, where one might expect sea ice. They are usually created by strong winds that blow ice away from the coast leaving open areas, or by gaps appearing on the ocean’s surface, when flowing ice gets blocked by an impediment, like an ice shelf.

The Antarctic waters are rich in nutrients. The lack of ice, combined with shallow coastal waters, provides the top layers of the ocean with added sunlight, so polynyas offer ideal conditions for phytoplankton blooms. Because the ice around polynyas is thin in the early spring when the long Austral day begins, they are the first areas to get strong sunlight. The open waters retain more heat, further thinning ice cover and leading to early, intense, and short-lived plankton blooms. These blooms feed krill, a tiny, shrimp-like animal, which in turn are eaten by Adelie Penguins, seabirds, seals, whales, and other animals.

Although relatively small in area, coastal polynyas play a disproportionately important role in many physical and biological processes in Polar Regions. In eastern Antarctica, more than 90 percent of all Adelie Penguin colonies live next to coastal polynyas. Polynya productivity explains, to a great extent, the increase and decrease in penguin population.

“It’s the first time anyone has ever looked comprehensively at the biology of the polynyas,” said Kevin Arrigo, assistant professor of Geophysics at Stanford University, Stanford, Calif. “No one had any idea how tightly coupled the penguin populations would be to the productivity of these polynyas. Any changes in production within these polynyas are likely to lead to dramatic changes in the populations of penguins and other large organisms,” Arrigo said.

The study, which appeared in a recent issue of the Journal of Geophysical Research, used satellite-based estimates to look at interannual changes in polynya locations and sizes; abundance of microscopic free-floating marine plants called phytoplankton, which are the base of the polar ocean food chain; and the rate at which phytoplankton populations thrive. Covering five annual cycles from 1997 to 2002, 37 coastal polynya systems were studied.

The largest polynya studied was located in the Ross Sea (396,500 square kilometers or 153,100 square miles; almost the size of California). The smallest was located in the West Lazarev Sea (1,040 square kilometers or 401.5 square miles). Most polynyas, at their maximum area in February, were less than 20,000 square kilometers (7,722 square miles).

Data from NASA’s Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and NOAA’s Advanced Very High Resolution Radiometer (AVHRR) provided weekly measurements of chlorophyll and temperature that were used in a computer model to estimate phytoplankton productivity. The researchers found, taken together, the Ross Sea, Ronne Ice Shelf, Prydz Bay, and Amundsen Sea polynyas were responsible for more than 75 percent of total plankton production.

The researchers were surprised to find how closely connected the Adelie Penguins were to the productivity of their local polynyas. The more productive polynyas supported larger penguin populations. The more abundant krill fed more penguins, and the birds had shorter distances to go to forage, which reduced exposure to predators and other dangers.

The NASA Oceanography Program, the National Science Foundation, and the U.S. Department of Energy funded this research. NASA’s Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.

Original Source: NASA News Release

Posted on by Fraser Cain

Chinese Could Launch Very Soon

The Chinese might be days away from launching their first humans into space, according to various experts and insiders. Normally quiet about future launch plans, the Chinese government is starting to make more comments about what could happen soon – the launch could happen as early as this weekend, but others believe the launch won’t happen before October 15 as government officials are in a series of meetings and would like to be present for the launch. All of the astronauts (or yuhangyuan) are at the launch facility and the Shenzhou 5 spacecraft has been mated to the top of its Long March rocket.

Posted on by Fraser Cain

Virgo Cluster Sucks in Distant Galaxy

Image credit: Chandra

A new image taken by the Chandra X-Ray Observatory shows the elliptical galaxy M86 and its 200,000 light-year long tail. This gigantic galaxy is located in the Virgo galaxy cluster and moving 4.8 million kilometres per hour through clouds of gas in the cluster. The Virgo cluster is hurtling away from us, but M86 is on the opposite side and being pulled into it, so the net effect is that M86 is actually one of the few galaxies actually moving towards our own Milky Way.

This composite X-ray (blue)/optical (orange) image of M86 shows gas being swept out of the galaxy to form a long tail more than 200,000 light years in length. Located in the Virgo galaxy cluster, this enormous elliptical galaxy is moving at about 3 million miles per hour through diffuse hot gas that pervades the cluster. The supersonic motion of M86 produces pressure that is stripping gas from the galaxy and forming the spectacular tail.

M86 has been pulled into the Virgo galaxy cluster and accelerated to a high speed by the enormous combined gravity of dark matter, hot gas, and hundreds of galaxies that comprise the cluster. The infall of the galaxy into the cluster is an example of the process by which galaxy groups and galaxy clusters form over the course of billions of years.

The galaxy is no longer an “island universe” with an independent existence. It has been captured and its gas is being swept away to mix with the gas of the cluster, leaving an essentially gas-free galaxy orbiting the center of the cluster along with hundreds of other galaxies.

M86 is an unusual galaxy in that it is one of a small number of galaxies that are moving toward Earth, rather than receding with the general expansion of the Universe. This expansion is carrying the Virgo cluster away from us at a speed of about 2 million miles per hour, but M86 is falling into the Virgo cluster from the far side of the cluster, giving it a net velocity of about one million miles per hour toward Earth.

Original Source: Chandra News Release

Posted on by Fraser Cain

Small Asteroid Came Very Close

Image credit: Lowell Observatory

Asteroid 2003 SQ222 whizzed by the Earth last week, missing us by only 88,000 kilometres. The rock wasn’t large, only 3 to 6 metres across, but if it had hit the Earth it probably wouldn’t have caused damage as would burn up in the atmosphere. The asteroid was discovered by the Lowell Observatory and several amateur astronomers who collaborated to track its motion as it flew away from the Earth – unfortunately, they didn’t notice it until it had already passed us. Objects of this size do strike the Earth about once a year, and create a spectacular fireball in the sky for anyone lucky enough to spot it.

A small asteroid, perhaps 3 to 6 meters in diameter?the size of a room or house?came within 88,000 km of Earth late on Friday, September 27. Less than a quarter of the distance to the Moon, this is the closest well-documented Earth encounter of an asteroid that has not struck our atmosphere.

?In a good month, we find five to 10 near-Earth asteroids, but usually, the ones we discover are as big as mountains, or at least football stadiums, so this one was unique for us,? said Edward Bowell, Director of Lowell Observatory?s Near-Earth-Object Search (LONEOS).

Known as 2003 SQ222, the asteroid was imaged a few hours after close approach by Michael Van Ness, a graduate student at Northern Arizona University, Flagstaff.

LONEOS is one of five teams funded by NASA?s Near Earth Objects Observations program to look for asteroids and comets that could come close to or strike our planet. LONEOS is the third leading discoverer of asteroids.

The first images of SQ222 were made on a series of CCD-camera frames (charge-coupled device) taken for Minor Planet Research, an organization collaborating with LONEOS on a project with an aim of having high school students make asteroid discoveries at the Challenger Learning Center in Peoria, Arizona. Robert Cash, of MPR, used automatic moving-object detection software to find three trailed images of an object moving at 20 degrees per day, almost twice as fast as the Moon, across the sky. Cash relayed his discovery back to Lowell Observatory and to the international clearinghouse for asteroid and comet observations, the Minor Planet Center, in Cambridge Massachusetts.

Predicted positions were posted on the MPC?s Near-Earth Object Confirmation Page so observers worldwide could follow the object.

Meanwhile, Bowell noticed that it was possible to compute a fairly reliable orbit. ?The orbit showed clearly that SQ222 had passed within a quarter of the Moon?s distance to the Earth, some 11 hours before being discovered,? said Bowell. ?So, I e-mailed our results to the Minor Planet Mailing List, to which hundreds of amateur and professional astronomers subscribe, with a request for further observations.?

Brian Skiff, LONEOS? chief observer, acquired fresh CCD frames on September 29, but the LONEOS team was unable to locate the asteroid?s images. Once again, Bob Cash found the by then very faint images of the asteroid after visually searching the frames for more than three hours in the wee hours of September 30th. You can view two sequences of LONEOS images of SQ222.

Independently, British amateur astronomer Peter Birtwhistle, using a 30-cm telescope west of London, was able to image the asteroid. ?It is remarkable that Birtwhistle was able to detect the asteroid using such a small telescope,? said Bowell. ?He did so by tracking the motion of the asteroid and by aligning and co-adding (or stacking) the frames to bring out the faint asteroid images.?

?The essential rapid teamwork between Lowell Observatory and keen amateur astronomers made it possible to confirm and image this fast-moving, small asteroid as it shot past us,? said Bowell.

SQ222?s known brightness and distance allow calculation of its size. Most asteroids have either coal-black surfaces or are about four times more reflective. Bowell estimates the asteroid to be just 3 to 6 meters in diameter, most likely making it the smallest asteroid for which we have a reliable orbit. (Smaller and closer asteroids have been seen in space, especially by the Spacewatch team at the University of Arizona, but it has not been possible to follow them long enough to secure good orbits.)

Perhaps the final detection of SQ222 was made by British astronomer Alan Fitzsimmons (Queen?s University Belfast) on October 2. Fitzsimmons, working through thin cloud, managed to detect the asteroid using the 2.5-m Isaac Newton Telescope at La Palma in the Canary Islands. By then, SQ222, receding rapidly from Earth, was about 100 times fainter than at discovery.

After Fitzsimmons? observations, the orbit of SQ222 was good enough to compute a reliable value of what astronomers call the minimum orbital intersection distance, (MOID).

This is the minimum distance between the orbit of the asteroid and that of the Earth. Bowell calculated the MOID to be a little over 4 Earth radii (about 27,000 km).

?This distance is, roughly speaking, the very closest the asteroid could have come to the center of the Earth during its fly-by,? said Bowell. ?Therefore, SQ222 could not possibly have struck the Earth.? Even if it could have, it would have exploded harmlessly in the upper atmosphere, with an energy comparable to that of a small atomic bomb, as friction with the air vaporized its surface, added Bowell.

?Objects the size of SQ222 actually do burn up in Earth?s atmosphere every year or so, producing a spectacular light show,? said Bowell.

In what is most likely a coincidence, an intense shower of meteorites was reported in India about 10 hours before SQ222?s closest approach to Earth. Could the asteroid and the meteorites be fragments of a larger asteroid that was broken apart by a collision with another asteroid or by tidal disruption during a previous very close Earth approach? It seems very unlikely, but work is ongoing to test the plausibility of the idea.

Will SQ222 make another close pass by Earth? It is hard to say, as the orbit is not accurate enough to make reliable predictions for more than a few years into the future. Certainly, there seems no possibility of it returning within the next decade. Also, SQ222 will be too faint to see in the foreseeable future, even using the most powerful telescopes.

Original Source: Lowell News Release

Posted on by Fraser Cain

World Space Week Begins

People from 50 countries are celebrating space exploration as part of World Space Week – from October 4 to 10, 2003. Lance Bass, member of the pop group NSYNC, is the event’s youth spokesman, and will be traveling to various schools in the US to help build young students’ enthusiasm for space. Several other events are planned for this week, including a question and answer session with the astronauts on board the International Space Station. The first World Space Week was declared by the United Nations in 1999.

Posted on by Fraser Cain

NASA Targeting September Shuttle Launch

NASA has set a target date of September 2004 for when the first space shuttle will launch since the Columbia disaster. The agency was originally targeting earlier in the year, but they felt they needed more time to develop tracking and repair systems to fulfill the safety requirements suggested by the Columbia accident investigation. The improvements include new camera systems to watch the shuttle launch, a way for the astronauts to repair damage while they’re in space, and modifications to the external fuel tank to prevent foam from hitting the shuttle in launch. The next shuttle to launch will likely be Atlantis.