Posted on by Fraser Cain

Formation of Stars is On the Decline

Image credit: SDSS

The age of star formation in the Universe is drawing to a close, according to a new report from the Sloan Digital Sky Survey. A team of astronomers analyzed the colour of an enormous number of nearby galaxies and found that they contained less young stars than more distant galaxies. Since light takes so long to travel, the more distant galaxies are seen as they appeared many billion years ago. The number of new stars being formed has been on the decline since about 6 billon years ago, when our own Sun formed.

The universe is gently fading into darkness according to three astronomers who have looked at 40,000 galaxies in the neighbourhood of the Milky Way. Research student Ben Panter and Professor Alan Heavens from Edinburgh University’s Institute for Astronomy, and Professor Raul Jimenez of University of Pennsylvania, USA, decoded the “fossil record” concealed in the starlight from the galaxies to build up a detailed account of how many young, recently-formed stars there were at different periods in the 14-billion-year existence of the universe. Their history shows that, for billions of years, there have not been enough new stars turning on to replace all the old stars that die and switch off. The results will be published in the Monthly Notices of the Royal Astronomical Society on 21 August 2003.

“Our analysis confirms that the age of star formation is drawing to a close”, says Alan Heavens. “The number of new stars being formed in the huge sample of galaxies we studied has been in decline for around 6 billion years – roughly since the time our own Sun came into being.”

Astronomers already had evidence that this was the case, mainly from observing galaxies so far away that we see them as they were billions of years ago because of the great length of time their light has taken to reach us. Now the same story emerges strongly from the work of Panter, Heavens and Jimenez, who for the first time approached the problem differently and used the whole spectrum of light from an enormous number of nearby galaxies to get a more complete picture.

Galaxies shine with the combined light of all the stars in them. Most of the light from young stars is blue, coming from very hot massive stars. These blue stars live fast and die young, ending their lives in supernova explosions. When they have gone, they no longer outshine the smaller red stars that are more long-lived. Many galaxies look reddish overall rather than blue – a broad sign that most star formation happened long ago.

In their analysis, Panter, Heavens and Jimenez have used far more than the simple overall colours of the galaxies, though. The spectrum observations they used come from the Sloan Digital Sky Survey and the volume of data involved was so vast, that the researchers had to develop a special lossless data compression method, called MOPED, to allow them to analyse the sample in a reasonable length of time, without losing accuracy.

Original Source: RAS News Release

Posted on by Fraser Cain

SCISAT Ready for Launch Tuesday

Image credit: CSA

Everything is ready to go for the launch of the Canadian Space Agency’s Scientific Satellite Atmospheric Chemistry Experiment (SCISAT-1) on board a Pegasus XL rocket on Wednesday, August 13. If it all goes as planned, the L-1011 aircraft will carry the Pegasus rocket over the Pacific Ocean, and release it at 0210 GMT (10:10 pm EDT Tuesday) to carry SCISAT into orbit. SCISAT will help scientists track the chemical processes that control the distribution of ozone in the Earth’s atmosphere.

The Canadian Space Agency’s Scientific Satellite Atmospheric Chemistry Experiment (SCISAT-1) is scheduled to launch on Tuesday, August 12, between 10:05 and 11:02 p.m. EDT.

An L-1011 jet aircraft departing from Vandenberg Air Force Base (VAFB), Calif., will carry the Pegasus XL vehicle that will launch SCISAT-1. The L-1011 will drop the Pegasus, and its 330-pound spacecraft, over the Pacific Ocean at approximately 10:10 p.m. EDT. The SCISAT-1 mission will provide scientists with improved measurements of the chemical processes that control the distribution of ozone in Earth’s atmosphere.

The pre-launch press conference is at the NASA Resident Office at VAFB, Monday, August 11, at 4 p.m. EDT. The press conference will be carried live on NASA TV with question and answer capability available from NASA Headquarters; KSC; and Goddard Space Flight Center, Greenbelt, Md.

On launch day, media should meet at the VAFB main gate at 8:30 p.m. EDT to be escorted to the runway for the L-1011 take-off. Media may follow the release and launch of Pegasus/SCISAT from the viewing room of the NASA Mission Director’s Center, Building 840 on South VAFB.

Assuming a nominal flight of the Pegasus launch vehicle, a post-launch news conference will not be held. However, launch vehicle and spacecraft representatives will be available afterward to informally answer questions from the media.

Launch coverage on NASA Television begins at 8:30 p.m. EDT through spacecraft separation from the Pegasus vehicle. NASA TV is broadcast on AMC-9, Transponder 9C, C-band, located at 85 degrees west longitude. The frequency is 3880.0 MHz. Polarization is vertical, and audio is monaural at 6.80 MHz. Live launch commentary and audio of the Pegasus/SCISAT briefing will be available on the “V” audio circuits available at: 321/867-1220/1240/1260/7135.

The Pegasus/SCISAT News Center at the NASA VAFB Resident Office will be staffed starting on Monday from 11 a.m. to 7:30 p.m. EDT; phone: 805/605-3051/3001. A recorded status report is available at: 805/734-2693.

Click the “Watch NASA TV Now!” link for live Web cast at:

http://www.nasa.gov

NASA’s Earth Science Enterprise sponsors the mission and is responsible for countdown and launch management. Orbital Sciences Corp. will provide the launch service, and the Canadian Space Agency is responsible for spacecraft development.

Original Source: NASA News Release

Posted on by Fraser Cain

SpaceShipOne Completes First Drop Test

Scaled Composite’s SpaceShipOne completed its first glide test on Thursday, after it was released from the White Knight aircraft at an altitude of 14,300 metres. The X-Prize candidate was taken through a series of tests in the air, and then landed at a runway in the Mojave desert. Since it was unveiled in April, 2003, SpaceShipOne is considered one of the front runners to win the $10 million X-Prize for the first privately-built spacecraft to reach an altitude of 100 km twice within 2 weeks.

Posted on by Fraser Cain

Cosmonaut Ties the Knot From Space

Cosmonaut Yuri Malenchenko married his fianc?, Ekaterina Dmitriev, on Sunday, but it wasn’t a normal ceremony. Dimitriev was in Houston while Malenchenko hurtled 385 kilometres above on the International Space Station. The couple took advantage of Texas law, which allows weddings to take place even if one person isn’t present. The Russian Aerospace Agency tried to block the wedding in the beginning, but eventually backed down, and gave the couple their blessing.

Posted on by Fraser Cain

Hubble Sees One Galaxy Consuming Another

A new image taken by the Hubble Space Telescope shows a large galaxy gobbling up a smaller one; a process anticipated by astronomers, but never directly seen before. Astronomers used the Keck Telescope in Hawaii to confirm that the dwarf galaxy is being consumed by measuring the rate that stars are streaming towards the larger galaxy. The stars of the smaller galaxy will eventually form a spherical halo surrounding the flattened disk of the larger galaxy.

Posted on by Fraser Cain

Sea Launch Lofts Echostar IX/Telstar 13

Image credit: Sea Launch

The dual-use Echostar IX/Telstar 13 satellite was successfully placed into orbit Thursday on board a Zenit-3SL which was launched from the Sea Launch platform floating in the middle of the Pacific Ocean. The communications satellite separated 66 minutes after launch, and will eventually provide television services to the United States. This is the tenth launch for Sea Launch, which is expected to have two more launches this year.

Sea Launch, the world?s most reliable launch service provider for heavy commercial communication satellites, today successfully launched the EchoStar IX/Telstar 13 satellite to orbit for EchoStar Communications Corporation and Loral Skynet.

A Zenit-3SL launch vehicle lifted off at 8:31 pm PDT (3:31 GMT) from the Odyssey Launch Platform positioned at 154 degrees West Longitude, on the Equator. All systems performed nominally throughout the flight. The Block DM-SL upper stage inserted the 4,737 kg (10,443 lb) EchoStar IX/Telstar 13 satellite into a high perigee geosynchronous transfer orbit. As planned, the spacecraft?s first signal was acquired at 9:46 pm PDT (4:46 GMT), shortly after spacecraft separation, by a ground station in Western Australia. The spacecraft will be located in geostationary orbit at 121 degrees West Longitude.

Upon completion of the successful mission, Jim Maser, president and general manager of Sea Launch, said, ?I want to congratulate Space Systems/Loral (SS/L), EchoStar Communications Corporation, Loral Skynet and the entire Sea Launch team for a great job! Once again, we achieved a very smooth operation. This is clearly a tribute to the skill, dedication and experience of everyone in the Sea Launch organization and I am very proud to be part of this talented group. We have just completed our second launch in less than two months and we expect to continue this tempo well through next year.

?This mission also marked our tenth launch and the first for SS/L,? Maser continued. ?We appreciate the confidence and trust they and their customers have demonstrated and we look forward to the many more SS/L launches on our manifest. We also welcome the opportunity to serve EchoStar and Loral Skynet in the future.?

SS/L built the EchoStar IX/Telstar 13 spacecraft in Palo Alto, Calif. The Ku-band capacity will enhance EchoStar?s U.S. DISH Network satellite television service. EchoStar has also equipped the spacecraft with the first commercial Ka-band spot-beam payload in the United States. In addition, in a unique multi-band, satellite-sharing arrangement, Loral Skynet will own and operate the satellite?s C-band capacity, as Telstar 13, which will provide television programmers with North American coverage.

Sea Launch Company, LLC, headquartered in Long Beach, Calif., is a world leader in providing heavy-lift commercial launch services. This multinational partnership offers the most direct and cost-effective route to geostationary orbit. With the advantage of a launch site on the Equator, the reliable Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, offering best value plus schedule assurance. Sea Launch has a current backlog of 14 firm launch contracts. For additional information and images of this successfully completed mission, visit the Sea Launch website at: www.sea-launch.com

Original Source: Sea Launch

Posted on by Fraser Cain

ESA’s Lunar Mission Prepares for Launch

The European Space Agency’s first spacecraft mission to the Moon, SMART-1, is being prepared for launch at the end of August. The spacecraft was delivered in mid-July to the ESA’s space centre in Kourou, French Guiana, and is expected to launch on August 29. The spacecraft will take 16 months to reach the Moon, following a long spiral trajectory, and using its efficient ion engine to gradually put it into orbit around the Moon. SMART-1 will then search for evidence of water-ice in craters near the Moon’s poles.

Europe?s first probe to the Moon, SMART-1, is about to begin a unique journey that will take it into orbit around our closest neighbour, powered only by an ion engine which Europe will be testing for the first time as main spacecraft propulsion.

The European Space Agency?s SMART-1 spacecraft was delivered to Kourou, French Guiana, on July 15 and is currently being prepared for launch atop an Ariane 5 during the night from August 28 to 29. The launch window will open at 20:04 local time (01:04 on August 29 morning CEST) and will remain open for 26 minutes.

The 367 kg spacecraft will share Ariane?s V162 launch with two commercial payloads: the Indian Space Research Organisation?s Insat 3E and Eutelsat?s e-Bird communication satellites. The smallest spacecraft in the trio, SMART-1, will travel in the lower position, inside a cylindrical adapter, and will be the last to be released.

Europe’s Ariane-5 launcher will put SMART-1 into orbit
A generic Ariane 5 will be in charge of placing these three payloads in a standard geostationary transfer orbit from which each will begin its own journey towards its final operational orbit. SMART-1, powered by its ion engine, will reach its destination in about 16 months, having followed a long spiralling trajectory.

SMART-1?s ion engine will be used to accelerate the probe and raise its orbit until it reaches the vicinity of the Moon, some 350,000 to 400,000 km from Earth. Then, following gravity assists from a series of lunar swingbys in late September, late October and late November 2004, SMART-1 will be ‘captured’ by the Moon?s gravity in December 2004 and will begin using its engine to slow down and reduce the altitude of its lunar orbit.

Testing breakthrough technologies and studying the Moon
SMART-1 is not a standard outer space probe. As ESA?s first Small Mission for Advanced Research in Technology, it is primarily designed to demonstrate innovative and key technologies for future deep space science missions. However, once it has arrived at its destination, it will also perform an unprecedented scientific study of the Moon. SMART-1 is a very small spacecraft (measuring just one cubic metre). Its solar arrays, spanning 14 metres, will deliver 1.9 kW of power, about 75% of which will be used for the probe’s ‘solar electric’ propulsion system.

Close-up view of SMART-1’s stationary plasma thruster
In its role as technological demonstrator, SMART-1?s primary goal is to test this new solar electric propulsion system. This is a form of continuous low-thrust engine that uses electricity derived from solar panels to produce a beam of charged particles that pushes the spacecraft forward. Such engines are commonly called ion engines, and engineers consider them essential for future, long-range space missions. SMART-1 will also test miniaturised spacecraft equipment and instruments, a navigation system that, in the future, will allow spacecraft to autonomously navigate through the solar system, and in addition to a new short-wavelength communication system, a space communication technique by means of which SMART-1 will try to establish a link with the Earth using a laser beam.

Once it enters into a near-polar orbit around the Moon in January 2005, SMART-1 will also become a science platform for lunar observation. SMART-1 will search for signs of water-ice in craters near the Moon?s poles, provide data to shed light on the still uncertain origin of the Moon, and reconstruct its evolution by mapping its topography and the surface distribution of minerals and key chemical elements.

SMART-1 will be the second ESA-led planetary mission to be launched in 2003 after Mars Express in June.

Original Source: ESA News Release

Posted on by Fraser Cain

Malfunctioning Instrument on Spirit

An instrument on board Spirit, one of NASA’s Mars Exploration Rovers, has malfunctioned, potentially limiting the amount of data that can be retrieved from the surface of Mars. The instrument is called a Mossbauer spectrometer, and it’s designed to determine the presence and abundance of iron-bearing minerals in the rocks of Mars. If the glitch can’t be worked out, it will still be able to detect the mineral, just not its quantity. Engineers still have several months to get this fixed before Spirit arrives at Mars on January 3.

Posted on by Fraser Cain

Asteroids Named for Lost Astronauts

Image credit: NASA

Seven asteroids were recently renamed to honour the astronauts of the space shuttle Columbia. The asteroids are all 5 to 7 km long, and were discovered on the nights of July 19-21, 2001 at the Palomar Observatory near San Diego by astronomer Eleanor F. Helin. NASA’s Jet Propulsion Laboratory proposed the idea, and it was recently approved by the International Astronomical Union, which is responsible for maintaining the names of celestial objects.

The final crew of the Space Shuttle Columbia was memorialized in the cosmos as seven asteroids orbiting the sun between Mars and Jupiter were named in their honor today.

The Space Shuttle Columbia crew– Commander Rick Husband; pilot William McCool; Mission Specialists Michael Anderson, Kalpana Chawla, David Brown, Laurel Clark; and Israeli payload specialist Ilan Ramon, will have celestial memorials, easily found from Earth.

The names, proposed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif., were recently approved by the International Astronomical Union. The official clearinghouse of asteroid data, the Smithsonian Astrophysical Observatory’s Minor Planet Center, released the dedication today.

The seven asteroids were discovered at the Palomar Observatory near San Diego on the nights of July 19-21, 2001, by former JPL astronomer Eleanor F. Helin, who retired in July 2002. The seven asteroids range in diameter from five to seven kilometers (3.1 to 4.3 miles). The Palomar Observatory is owned and operated by the California Institute of Technology, Pasadena.

“Asteroids have been around for billions of years and will remain for billions more,” said Dr. Raymond Bambery, Principal Investigator of JPL’s Near-Earth Asteroid Tracking System. “I like to think that in the years, decades and millennia ahead people will look to the heavens, locate these seven celestial sentinels and remember the sacrifice made by the Columbia astronauts.?

The 28th and final flight of Columbia (STS-107) was a 16-day mission dedicated to research in physical, life and space sciences. The seven astronauts aboard Columbia worked 24 hours a day, in two alternating shifts, successfully conducting approximately 80 separate experiments. On February 1, 2003, the Columbia and its crew were lost over the western United States during the spacecraft’s re-entry into Earth’s atmosphere.

Asteroids are rocky fragments left over from the formation of the solar system about 4.6 billion years ago. Most of the known asteroids orbit the Sun in a belt between Mars and Jupiter. Scientists think there are probably millions of asteroids, ranging in size from less than one kilometer (.62 mile) wide to hundreds of kilometers across.

More than 100,000 asteroids have been detected since the first was discovered back on January 1, 1801. Ceres, the first asteroid discovered, is also the largest at about 933 kilometers (580 miles) in diameter.

The Near-Earth Asteroid Tracking System is managed by JPL for NASA’s Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology.

Information about JPL’s Near-Earth Asteroid Tracking System is available at http://neat.jpl.nasa.gov. More information on the newly named asteroids is at http://www.jpl.nasa.gov/releases/2003/columbia-tribute.cfm.

For information about NASA on the Internet, visit: http://www.nasa.gov.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Hubble Looks at Our Closest Cluster

Image credit: Hubble

The newest image from the Hubble Space Telescope reveals one of the nearest globular star clusters, NGC 6397, located only 8,200 light years away in the constellation Ara. The stars in this cluster are packed one million times more densely than our own galactic neighborhood; collisions between stars occur every few million years. Two colliding stars may merge to become a “blue straggler”; a bright, young hot star that looks very different from the rest of the stars in the cluster.

This Hubble Space Telescope view of the core of one of the nearest globular star clusters, called NGC 6397, resembles a treasure chest of glittering jewels. The cluster is located 8,200 light-years away in the constellation Ara.

Here, the stars are jam-packed together. The stellar density is about a million times greater than in our Sun’s stellar neighborhood. The stars are only a few light-weeks apart, while the nearest star to our Sun is over four light-years away.

The stars in NGC 6397 are in constant motion, like a swarm of angry bees. The ancient stars are so crowded together that a few of them inevitably collide with each other once in a while. Near misses are even more common. Even so, collisions only occur every few million years or so. That’s thousands of collisions in the 14-billion-year lifetime of the cluster.

These Hubble images were taken for a research program aimed at studying what is left behind when such collisions and near misses occur. When direct collisions occur, the two stars may merge to form a new star called a “blue straggler”; these hot, bright, young stars stand out among the old stars that make up the vast majority of stars in a globular cluster. Several such bright blue stars are visible near the center of the cluster in the Hubble Heritage image.

If two stars come close enough together without actually colliding, they may “capture” each other and become gravitationally bound. One type of binary that might form this way is a “cataclysmic variable”? a pairing of a normal, hydrogen-burning star and a burned-out star called a white dwarf. In a binary system, the white dwarf will pull material off the surface of the normal star. This material encircles the white dwarf in an “accretion disk,” and eventually falls onto it. The result of this accretion process is that cataclysmic variables are, as the name suggests, variable in brightness. The heat generated by the accreting material also generates unusual amounts of ultraviolet and blue light.

To search for cataclysmic variables, the program consisted of a series of 55 images of the cluster taken over a period of about 20 hours. Most of the images were taken in ultraviolet and blue filters; a few images were also taken at green and infrared wavelengths. By comparing the brightness of all the stars in all the images, the Hubble astronomers were able to identify several cataclysmic variable stars in the cluster. Comparison of their brightness in the different filters confirmed that they were emitting copious amounts of ultraviolet light. A few of these stars can be seen in the Hubble Heritage image as faint blue or violet stars.

One of the more intriguing results of this study was completely unexpected. Three faint blue stars can be seen near the center of the cluster ? in the Hubble Heritage image they appear turquoise. These three stars don’t vary in brightness at all, and were clearly not cataclysmic variables. These stars may be very-low-mass white dwarfs, formed in the cores of giant stars whose evolution is somehow interrupted before a full-fledged white dwarf has time to form.

Such an interruption might occur as the result of a stellar collision or an interaction with a binary companion. When a giant star interacts with another star, it can lose its outer layers prematurely, compared to its normal evolution, exposing its hot, blue core. The end result will be a white dwarf of a smaller mass than would have otherwise ensued. In any case, these unusual stars are yet more evidence that the center of a dense globular cluster is a perilous place to reside.

A large number of normal white dwarfs were also identified and studied. These stars appear throughout the cluster, since they form through normal stellar evolution processes and don’t involve any stellar interactions, which occur predominantly near the cluster center. Nearly 100 such burned-out stars were identified in these images, the brightest of which can be seen here as faint blue stars.

This Hubble image is a mosaic of two sets of images taken several years apart by the Wide Field Planetary Camera 2. Archival data from science teams led by Jonathan Grindlay (Harvard University) and Ivan King (University of California, Berkeley), taken in 1997 and 1999, were combined with Hubble Heritage data taken in 2001. Adrienne Cool (San Francisco State University), who was also on both archival science teams, worked with the Hubble Heritage team to acquire the new observations.

Original Source: Hubble News Release