Posted on by Fraser Cain

Mars Rover Should Work Fine

Image credit: NASA/JPL

NASA engineers have been working through a problem with one of the Mars rovers currently traveling to the Red Planet, and they think they’ve got a solution. Back in August, engineers detected that Spirit’s M?ssbauer spectrometer – a device for identifying iron-bearing rocks – was sending back incorrect readings. They’ve been able to compensate for the readings, so long as Spirit continues to behave on Mars as it’s working right now. The rovers will land on Mars in January 2004.

A series of tests of one of the science instruments on NASA’s Mars Exploration Rover Spirit has enabled engineers and scientists to identify how to work around an apparent problem detected in August.

Tests now indicate that all of the science instruments on both Spirit and its twin, Opportunity, are in suitable condition to provide full capabilities for examining the sites on Mars where they will land in January.

Spirit’s M?ssbauer spectrometer, a tool for identifying the types of iron-bearing minerals in rocks and soil, returned data that did not fit expectations during its first in-flight checkup three months ago. A drive system that rapidly vibrates a gamma-ray source back and forth inside the instrument appeared to show partial restriction in its motion.

“The drive system is adjustable. We can change its velocity. We can change its frequency,” said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rovers’ science instruments. “We’ve found a set of parameters that will give us good M?ssbauer science if the instrument behaves on Mars the way it is behaving now.”

The corrective countermeasures include using a higher frequency of back-and-forth motion. “With these settings, whatever happened during launch will not decrease the quality of the data we get from the instrument,” said Dr. G?star Klingelh?fer, of Johannes Gutenberg University, Mainz, Germany, lead scientist for the M?ssbauer spectrometers on both rovers. “The instrument was designed with enough margin in its performance that we can make this change with no significant science impact.”

A possible explanation for the instrument’s behavior since launch is that intense vibration of the spacecraft during launch shook something inside the spectrometer slightly out of position, he said.

Landings on Mars are risky. Most attempts over the years have failed. And even if the spacecraft survives the landing, there is the potential that individual components could be damaged. “One remaining issue with the M?ssbauer Spectrometer on Spirit, as with all the instruments, is that we can’t be one hundred percent sure it?ll operate on Mars the way it?s operating now,” Squyres said. “We?ll breathe easier once we?ve done all our post-landing health checks.”

Another fact that has emerged from the in-flight checkouts of the M?ssbauer spectrometers on both spacecraft is that the internal calibration channel of the M?ssbauer spectrometer on Opportunity is not functioning properly. But because the instrument has the redundancy of a separate, completely independent external calibration method, this problem will not hamper use of that instrument, Squyres said.

Spirit is on course to arrive at Mars’ Gusev Crater at 04:35 Jan. 4, 2004, Universal Time, which is 8:35 p.m. Jan. 3, Pacific Standard Time and 11:35 p.m. Jan. 3, Eastern Standard Time. (These are “Earth received times,” meaning they reflect the delay necessary for a speed-of-light signal from Mars to reach Earth; on Mars, the landing will have happened nearly 10 minutes earlier.) Three weeks later, Opportunity will arrive at a level plain called Meridiani Planum on the opposite side of Mars from Gusev. Each rover will examine its landing area for geological evidence about the history of water there, key information for assessing whether the site ever could have been hospitable to life.

As of 13:00 Universal Time on Nov. 5 (5 a.m. PST; 8 a.m. EST), Spirit will have traveled 367.4 million kilometers (228.3 million miles) since its launch on June 10 and will still have 119.6 million kilometers (74.3 million miles) to go before reaching Mars. Opportunity will have traveled 296 million kilometers (184 million miles) since its launch on July 7 and will still have 160 million kilometers (99.2 million miles) to go to reach Mars.

The Jet Propulsion Laboratory, a division of the California Institute of Technology, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Additional information about the project is available from JPL at http://mars.jpl.nasa.gov/mer and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

NASA Marks the Third Year of People on the Station

Image credit: NASA

As of Sunday, November 2, the International Space Station has had humans on board for three years. The current crew, Expedition 8, arrived on board only a few weeks ago to replace Expedition 7 who had been on board for six months. With the loss of the space shuttle Columbia earlier this year, construction on the station has come to a halt. 76,000 kg of new equipment is currently being readied for launch, including scientific laboratories and new solar panels.

In a period that has exemplified the benefits of international cooperation in space, the International Space Station will complete a third year of permanent human presence aboard on Sunday, Nov. 2.

The third year of humans living aboard the station has been marked by the perseverance of the orbiting laboratory and international partnership through the tragedy of the Columbia accident.

“Every endeavour that continuously pushes the boundaries of human achievment can have times of both great triumph and great tragedy. The space agencies and nations around the world that are our partners in the Station understand that and they have experienced it,” ISS Program Manager Bill Gerstenmaier said. “The perseverance of crewed operations aboard the Station this year has brought the partnership closer together, and it will strengthen the Station through both the improvements in safety that we plan and the lessons we learn together.”

The eighth resident crew — Commander and NASA ISS Science Officer Mike Foale and Flight Engineer Alexander Kaleri — began a six-month stay aboard the complex Oct. 20.

The station remains the largest, most sophisticated and most powerful spacecraft ever built. Until the Space Shuttle fleet returns to flight, the transport of supplies and crews to the Station will be conducted by Russian spacecraft. The majority of power, cooling, volume and research capacity on the station are supplied by U.S. components. The station has a mass of almost 400,000 pounds and an interior volume roughly equal to that of a three-bedroom house. The U.S. Destiny Laboratory now houses seven different research facilities. The International Space Station partnership includes NASA; Rosaviakosmos, the Russian Space Agency; the Canadian Space Agency; the European Space Agency; and the Japanese Aerospace Exploration Agency.

At the Kennedy Space Center, Fla., 168,000 pounds of additional Station components are being prepared for launch when the Space Shuttle returns to flight. Those components will triple the number of science facilities aboard the orbiting laboratory, increase the total power available for research by over 80 percent and triple the surface area of the Station’s solar arrays. Among components at KSC is the second Station laboratory, the Japanese Experiment Module named Kibo.

Original Source: NASA News Release

Posted on by Fraser Cain

The Largest Flare Ever Seen

Image credit: NOAA

A massive flare erupted on the surface of the Sun yesterday that was so bright that it temporarily blinded the instruments on solar observation satellites. Astronomers believe this was the brightest flare that has ever been seen in modern times. Fortunately, this flare, and the following coronal mass ejection fired off to the side of the Sun, so very little material is expected to reach the Earth. The most powerful flares are the X-class; the most powerful flare ever seen before now was an X-20, but this could be an X-30, or even higher.

The NOAA Space Environment Center in Boulder, Colo., reports that an intense explosion occurred on the sun Tuesday at 2:29 p.m. EST. The violent eruption saturated X-ray detectors on NOAA?s GOES satellite, which monitors the sun and produces a new image every minute. NOAA space weather forecasters are still analyzing the event to see if this solar explosion will trigger another bout of radiation and geomagnetic storms. (Click NOAA satellite image for larger view of sun taken on Nov. 4, 2003, at 3:14 p.m. EST. Click here to view latest solar images. Please credit ?NOAA.?)

The explosion occurred in NOAA Region 486, an area that was about to rotate out of view of the Earth. This storm may only deal a glancing blow at the Earth given the position of the solar eruption. This region of the sun will be squarely aimed at Earth once again during Thanksgiving week.

(Click here to view mpeg animation of the sun with the latest solar eruption. The images begin Nov. 3 at 4:06 p.m. EST and end on Nov. 4 at 4:02 p.m. EST. Please note that this is a large file. Please credit “NOAA.”)

NOAA scientists are amazed at the amount of solar activity during the last two weeks. During this cycle of the sun, almost four years past solar maximum, explosions of this magnitude are a rarity.

NOAA forecaster Bill Murtagh said that a radio blackout is in progress. ?This is an R-5 extreme event. They don?t get much bigger than this.? An R-5 event is at the top of the NOAA space weather scales, which run 1 to 5.

Original Source: NOAA News Release

Posted on by Fraser Cain

Sun Launches Three More Flares

Image credit: NOAA

It looks like the Sun isn’t done with us yet. Over the last 24-hours, the Sun has hurled three more giant flares towards the Earth. None of these were as large as the flares that struck the Earth last week, but they’re still fairly strong. This should give people in the Northern and Southern latitudes another chance to see an aurora. The sunspots which have been generating all the storms are now rotating over to the side of the Sun and then they’ll go behind it, but they could return again in a few weeks to batter the Earth again.

The series of solar storms that have pummeled Earth continues as forecasters at the NOAA Space Environment Center in Boulder, Colo., observed three more explosions on the sun during the past 24 hours. The largest flare produced a coronal mass ejection, CME, that could strike Earth’s magnetic field by midday Monday. Forecasters are predicting a strong to severe (G-3 to G-4) storm for Monday and Tuesday, as measured by the NOAA space weather scales that run 1 to 5. This storming will provide another chance for those in the northern tier of the U.S. to see the northern lights or Aurora Borealis. (Click NOAA satellite image for larger view of sun taken on Nov. 3, 2003, at 11:34 a.m. EST. Click here to view latest solar images. Please credit ?NOAA.?)

Strong solar radiation and radio blackout storms were in progress on Sunday as a result of the large eruptions. NOAA sun spot regions 486 and 488, which produced these flares, are gradually moving to the western part of the sun and should be rotating out of sight in the next day or so. This might provide Earth with a break from the severe space storms it has experienced over the last 10 days. However, these regions could return to the front side of the sun in several weeks as they rotate back into view. In the 11-year solar cycle, The Earth is currently about three years past solar maximum. Solar maximum is the time when the sun is most active. Right now the sun is in its solar minimum phase.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation?s coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Original Source: NOAA News Release

Posted on by Fraser Cain

Giant Mirror Arrives at New Observatory

Image credit: UA

The construction of the world’s most powerful optical telescope took a significant step forward this week when the first of its huge mirrors was delivered. The Mount Graham International Observatory’s Large Binocular Telescope will eventually have twin 8.4 metre mirrors linked together, giving it an effective size of 11.8 metres. But the observatory will be able to view extremely faint objects as if it was 22.8 metres across – that’s 10 times the resolving power of the Hubble Space Telescope. The observatory will be completed in 2005.

The world?s most powerful optical telescope, which will allow astronomers to see planets around nearby stars in our galaxy, took a giant step closer to completion late last week when the first of its huge 27-foot diameter mirrors inched up a tortuous mountain road to its new home at Arizona?s Mount Graham International Observatory.

The 18-ton borosilicate “honeycomb” mirror was escorted up the mountain by a team of scientists, engineers, police, and heavy-haul specialists to the Large Binocular Telescope (LBT) facility. The mirror and its all-steel transport box, which together weighed 55 tons, were transported over 122 miles of Interstate and state highway, then up the narrow hairpin turns of the 29-mile Swift Trail to the Mount Graham International Observatory (MGIO) high above Safford, Ariz.

The journey to 10,480-foot-high Emerald Peak was a two-stage, multi-day affair that required five months of intense planning and preparation. This included a full-scale trial run with a dummy mirror in September.

“Everyone is aware that there?s real glass in there this time,” said J.T. Williams as the huge, yellow 48-wheeled transport rig rolled off pavement and onto the gravel road leading to the observatory. Williams, telescope assembly supervisor, walked every inch of the mountain road to inspect the surface and measure the turns during the transport operation.

Precision road grading by MGIO and Arizona Department of Transportation crews smoothed the worst of the washboard stretches of gravel, and haulers soon discovered that the near-vertical mirror load traveled best with a slight increase in speed over the washboard sections.

The mirror?s journey to Mount Graham began on Thursday, Oct. 23, when the Mirror Lab team and workers from Precision Heavy Haul, Inc. (PHH) loaded the mirror transport box and its precious cargo at UA?s Mirror Lab, which is located in the campus football stadium. The mirror-carrying convoy pulled out of the lab hours before dawn on Friday, accompanied by a 25-vehicle police escort that was organized by Mike Thomas of the UA Police Department. The police car-and-motorcycle escort formed a rolling blockade as the mirror rolled down I-10 and State Highway 191. They provided both traffic and mirror safety as the convoy averaged 45 mph to the MGIO base camp at the base of the Pinaleno Mountains.

Last Monday, Oct. 27, the team at base camp transferred the mirror to PHH?s Goldhofer trailer for the three-day, 29-mile journey to the telescope?s home on Emerald Peak. This 8,000-foot climb was made at about one mile per hour.

The Goldhofer trailer rests on six sets of eight wheels. Each wheel set has an independent hydraulic system that allowed the trailer to be accurately leveled, keeping the mirror upright as it negotiated the road?s banked turns.

“This is probably the most challenging job we?ve done,” said PHH President Mike Poppe, who expertly drove the Goldhofer to the telescope. PHH Vice President Jim Mussmann rode on the Goldhofer and monitored hydraulics, constantly adjusting the trailer to maintain the mirror’s center of gravity.

PHH, which is based in Phoenix, hauled the mirror cell (the structure that holds the mirror and its support system) to the LBT a week earlier and transported many other telescope parts to Mount Graham in 2002.

“Arizona was very fortunate to partner with Precision Heavy Haul, a group that wanted to work with the university as a team of one,” said LBT Associate Director Jim Slagle. “The alliance of Arizona scientists and engineers working alongside Precision Heavy Haul on the proper way to bring these pieces up the mountain turned out to be a successful operation.”

Although the mirror was transported to the mountain last week, its journey began back in 1997 when it was spun cast in the Mirror?s Lab?s giant rotating furnace. The Mirror Lab team has been developing new mirror technologies for the past two decades under the direction of UA Regents? Professor J. Roger Angel.

After it was cast, the mirror was polished using the lab?s innovative stressed-lap technique. The face of the deeply parabolic mirror (f/1.14) mirror is precise within a millionth of an inch over its entire surface.

The Mirror Lab is about to begin polishing the LBT?s second 8.4-meter primary mirror.

Work on the LBT began with construction of the telescope building in 1996 and is scheduled to be completed in 2005 when both mirrors are installed at the $100 million facility. The two mirrors together are valued at $22 million. The telescope building is a 16-story structure, the top ten floors of which rotate.

The LBT will have twin 8.4-meter mirrors on a single telescope mount, giving it the light-collecting area of an 11.8-meter (39-foot-diameter) telescope. But what really excites astronomers is that the LBT will make images of even faint objects as sharp as a 22.8-meter (75-foot) telescope would. This is nearly ten times sharper than the images from the Hubble Space Telescope. When the LBT is fully operational, it will be the world?s most powerful optical telescope, capable of imaging planets beyond our solar system. It will allow astronomers to peer deeper into the universe than ever before.

Astronomers won?t have to wait to 2005, however, to begin using the telescope. It will see first light with its first mirror next summer.

The telescope is a compact, stiff and innovative design produced by UA engineer Warren Davison in collaboration with Roger Angel and engineers in Italy. The major mechanical parts for the LBT were fabricated, pre-assembled and tested at the Ansaldo-Camozzi steel works in Milan, one of Italy?s oldest steel manufacturers. Then the telescope was disassembled and shipped by freighter to Houston, Texas, and overland to Safford, Ariz. The Italian-made mirror cell continued to the Mirror Lab, where Integration Team Leader Steve Warner and his team integrated the mirror support system into the cell for final optical tests before PHH hauled the mirror cell to the mountain two weeks ago.

Astronomers were delighted when the mirror reached its home last week.

“I?m both excited and exhausted simultaneously,” said LBT Project Director John M. Hill, who couldn?t be pried away from the mirror after it arrived at the 10,000-foot-high telescope enclosure on Thursday, Oct. 30. “We?ve been working on this mirror for a long time, and it?s great to see it ready to install in the telescope.”

LBT Associate Director Jim Slagle echoed Hill?s enthusiasm. “I?m terrifically excited,” he said. “Today we?re going to have an observatory. For the first time, we have a mirror. We have a mirror cell. And we?re going to have a telescope.”

Steward?s Associate Director Buddy Powell added, “This is a significant milestone in the process to make available the most powerful optical telescope in the world. It would not have been possible without the support of people in Graham County (Arizona), the State of Arizona, Ohio, Italy, and Germany. It is a perfect example of what people from wide and diverse backgrounds can accomplish by working together. We are very proud of their accomplishment.”

Steward Observatory Director Peter Strittmatter said, “Getting the first LBT 8.4-meter mirror to the observatory on Mount Graham is a major accomplishment, and a huge relief. The LBT team and those involved in the transportation are to be congratulated on their achievement. Arizonan?s can take enormous pride in this project.”

The University of Arizona, which also represents Arizona State University and Northern Arizona University on the project, holds a quarter partnership in the LBT. The Instituto Nazionale di Astrofisica, representing observatories in Florence, Bologna, Rome, Padua, Milan and elsewhere in Italy, is also quarter partner in the project. The Ohio State University and the Research Corp. each holds a one-eighth share, with Research Corp. providing participation for the University of Notre Dame, the University of Minnesota, and the University of Virginia. Germany is the fourth quarter partner in LBT, with contributing science institutions in Heidelberg, Potsdam, Munich, and Bonn.

Original Source: UA News Release

Posted on by Fraser Cain

First Light for New Infrared Observatory

Image credit: UH IfA

Astronomers from the University of Hawaii’s Institute for Astronomy released new images from their brand new 16-megapixel camera installed on the 2.2 metre telescope on Mauna Kea. This new camera provides a tremendous increase in resolution over the 1-megapixel camera the telescope was using before, and makes this telescope one of the most powerful on Earth for Infrared astronomy. The newly-released image is of galaxy NGC 891, which is 10 million light-years away in the constellation of Andromeda.

Astronomers from the University of Hawaii (UH), Institute for Astronomy (IfA) today released the first image from a gigantic new 16 Megapixel infrared camera recently mounted on the UH 2.2-meter (88-inch) Telescope on Mauna Kea. The new camera provides a sixteen-fold increase in sky coverage together with much higher sensitivity than the 1-Megapixel cameras in widespread use on telescopes for the last decade. Until larger telescopes have similar cameras, it makes the 30-year-old UH 2.2-meter telescope the most powerful in the world for infrared imaging.

The development of this new technology has been driven by the requirements of NASA’s James Webb Space Telescope (JWST), the next step beyond the Hubble Space Telescope and planned for launch within ten years. This 6 meter class space telescope with six times the collecting area of Hubble will be launched into an orbit far beyond the moon where it will cool to temperatures of -400 degrees Fahrenheit, allowing extremely sensitive infrared observations. NASA has selected the UH/RSC (Rockwell Scientific Company) detector technology for the camera on JWST and is expected to adopt it for several other instruments.

Funded by a nearly $7 million award from NASA Ames Research Center, a team at the IfA Hilo facility headed up by Dr. Don Hall, former IfA director, has partnered with the Rockwell Scientific Company in Camarillo, CA, in a four year program to develop 4 Megapixel chips utilizing new infrared detector materials and state of the art silicon chips which, at a size of nearly 2″ x 2″, are some of the largest ever produced. In partnership with GL Scientific, a Honolulu small business, the team has innovated a new approach to mounting the individual 4 Megapixel chips so that four of them can be “tiled” into a 16 Megapixel camera. This approach allows for even larger “mosaic” cameras in the future.

Hall emphasized that the project was run from Hilo. “The IfA team provided technical direction of both the development effort at Rockwell Scientific and the silicon chip fabrication at the UMC foundry in Taiwan,” he said. “In addition, we have established in Hilo a facility to test these new detectors that is widely regarded as the best available”. Hall also commented “complex instruments like this camera usually require extensive de-bugging once they are mounted at the telescope. It is a tribute to the technical excellence of the IfA staff and the superb equipment at the IfA facility that this camera produced science data on its first night”.

The galaxy imaged, NGC 891, is in the constellation Andromeda at a distance of about 10 million light years. It is of particular scientific interest because it is very similar to our own Milky Way Galaxy but is seen almost exactly edge-on. Dr. Richard Wainscoat and Peter Capak, who are analyzing the image, emphasized the importance of being able to image the entire galaxy in a single exposure with the new camera. “With smaller cameras, galaxies such as NGC 891 had to be imaged in small postage stamp sized pieces that had to be painstakingly pieced together – the new camera produces a better image in a tiny fraction of the time,” Wainscoat said. “By allowing us to image very large areas of the sky, this camera will allow us to detect some of the most distant galaxies in the Universe”.

Along with the JWST, large ground based telescopes are already racing to take advantage of this new technology. Two Mauna Kea projects, the Canada-France-Hawaii Telescope and the Gemini Telescopes, are forging ahead with 16 Megapixel infrared cameras and Rockwell Scientific has orders for several other cameras for telescopes in Chile.

IfA Director Dr. Rolf Kudritzki said “This project is an excellent example of IfA’s nurturing of extremely high-tech projects in its Hilo facility and there is an institutional commitment to continued support of such activities. It is particularly gratifying that a number of the key personnel on this project grew up in Hilo and were recruited back from the Mainland and that several others were recruited directly as graduates of UH Hilo. The project also provided important training for undergraduate assistants from UH Hilo, many of whom have gone on to positions in related fields”.

The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the Sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.

Original Source: IFA News Release

Posted on by Fraser Cain

ESO Provides Views of N44 Nebula

Image credit: ESO

The European Southern Observatory has released new images of nebula N44 in the Large Magellanic Cloud. Astronomers used the ESO’s Wide-Field-Imager on the 2.2 metre La Silla Observatory to capture the area with unprecedented clarity. N44 is approximately 1,000 light-years across and contains about 40 bright luminous blue stars. The blue stars live for a very short time and then explode as supernovae – some have already exploded in the area, creating some of the nebula’s visible material.

The two best known satellite galaxies of the Milky Way, the Magellanic Clouds, are located in the southern sky at a distance of about 170,000 light-years. They host many giant nebular complexes with very hot and luminous stars whose intense ultraviolet radiation causes the surrounding interstellar gas to glow.

The intricate and colourful nebulae are produced by ionised gas [1] that shines as electrons and positively charged atomic nuclei recombine, emitting a cascade of photons at well defined wavelengths. Such nebulae are called “H II regions”, signifying ionised hydrogen, i.e. hydrogen atoms that have lost one electron (protons). Their spectra are characterized by emission lines whose relative intensities carry useful information about the composition of the emitting gas, its temperature, as well as the mechanisms that cause the ionisation. Since the wavelengths of these spectral lines correspond to different colours, these alone are already very informative about the physical conditions of the gas.

N44 [2] in the Large Magellanic Cloud is a spectacular example of such a giant H II region. Having observed it in 1999 (see ESO PR Photos 26a-d/99), a team of European astronomers [3] again used the Wide-Field-Imager (WFI) at the MPG/ESO 2.2-m telescope of the La Silla Observatory, pointing this 67-million pixel digital camera to the same sky region in order to provide another striking – and scientifically extremely rich – image of this complex of nebulae. With a size of roughly 1,000 light-years, the peculiar shape of N44 clearly outlines a ring that includes a bright stellar association of about 40 very luminous and bluish stars.

These stars are the origin of powerful “stellar winds” that blow away the surrounding gas, piling it up and creating gigantic interstellar bubbles. Such massive stars end their lives as exploding supernovae that expel their outer layers at high speeds, typically about 10,000 km/sec.

It is quite likely that some supernovae have already exploded in N44 during the past few million years, thereby “sweeping” away the surrounding gas. Smaller bubbles, filaments, bright knots, and other structures in the gas together testify to the extremely complex structures in this region, kept in continuous motion by the fast outflows from the most massive stars in the area.
The new WFI image of N44

The colours reproduced in the new image of N44, shown in PR Photo 31a/03 (with smaller fields in more detail in PR Photos 31b-e/03) sample three strong spectral emission lines. The blue colour is mainly contributed by emission from singly-ionised oxygen atoms (shining at the ultraviolet wavelength 372.7 nm), while the green colour comes from doubly-ionised oxygen atoms (wavelength 500.7 nm). The red colour is due to the H-alpha line of hydrogen (wavelength 656.2 nm), emitted when protons and electrons combine to form hydrogen atoms. The red colour therefore traces the extremely complex distribution of ionised hydrogen within the nebulae while the difference between the blue and the green colour indicates regions of different temperatures: the hotter the gas, the more doubly-ionised oxygen it contains and, hence, the greener the colour is.

The composite photo produced in this way approximates the real colours of the nebula. Most of the region appears with a pinkish colour (a mixture of blue and red) since, under the normal temperature conditions that characterize most of this H II region, the red light emitted in the H-alpha line and the blue light emitted in the line of singly-ionised oxygen are more intense than that emitted in the line of the doubly-ionised oxygen (green).

However, some regions stand out because of their distinctly greener shade and their high brightness. Each of these regions contains at least one extremely hot star with a temperature somewhere between 30,000 and 70,000 degrees. Its intense ultraviolet radiation heats the surrounding gas to a higher temperature, whereby more oxygen atoms are doubly ionised and the emission of green light is correspondingly stronger, cf. PR Photo 31c/03.

Original Source: ESO News Release

Posted on by Fraser Cain

Closest Galaxy Discovered

Image credit: CNRS

An international team of astronomers have discovered a new galaxy colliding with our own Milky Way. This new galaxy, Canis Major, is located only 42,000 light years away from the centre of the Milky Way – it’s our new “closest galaxy”. Canis Major was discovered during an infrared survey of the sky, which allowed the astronomers to peer through the obscuring dust and gas of the Milky Way. Canis Major is quite small (as galaxies go); it only contains about a billion stars.

An international team of astronomers from France, Italy, the UK and Australia has found a previously unknown galaxy colliding with our own Milky Way. This newly-discovered galaxy takes the record for the nearest galaxy to the centre of the Milky Way. Called the Canis Major dwarf galaxy after the constellation in which it lies, it is about 25000 light years away from thesolar system and 42000 light years from the centre of the Milky Way. This i closer than the Sagittarius dwarf galaxy, discovered in 1994, which is also colliding with the Milky Way. The discovery shows that the Milky Way is building up its own disk by absorbing small satellite galaxies. The research is to be published in the Monthly Notices of the Royal Astronomical Society within the next few weeks.

The discovery of the Canis Major dwarf was made possible by a recent survey of the sky in infrared light (the Two-Micron All Sky Survey or “2MASS”), which has allowed astronomers to look beyond the clouds of dust in the disk of the Milky Way. Until now, the dwarf galaxy lay undetected behind the dense disk. “It’s like putting on infrared night-vision goggles,” says team-member Dr Rodrigo Ibata of Strasbourg Observatory. “We are now able to study a part of the Milky Way that has been previously out of sight”.

The new dwarf galaxy was detected by its M-giant stars =AD cool, red stars that shine especially brightly in infrared light. “We have used these rare M-giant stars as beacons to trace out the shape and location of the new galaxy because its numerous other stars are too faint for us to see,” explains Nicolas Martin, also of Strasbourg Observatory. “They are particularly useful stars as we can measure their distances, and so map out the three-dimensional structure of distant regions of the Milky Way disk.” In this way, the astronomers found the main dismembered corpse of the dwarf galaxy in Canis Major and long trails of stars leading back to it. It seems that streams of stars pulled out of the cannibalised Canis Major galaxy not only contribute to the outer reaches of the Milky Way’s disk, but may also pass close to the Sun.

Astronomers currently believe that large galaxies like the Milky Way grew to their present majestic proportions by consuming their smaller galactic neighbours. They have found that cannibalised galaxies add stars to the vast haloes around large galaxies. However, until now, they did not appreciate that even the disks of galaxies can grow in this fashion. Computer simulations show that the Milky Way has been taking stars from the Canis Major dwarf and adding them to its own disk – and will continue to do so.

“On galactic scales, the Canis Major dwarf galaxy is a lightweight of about only one billion Suns,” said Dr. Michele Bellazzini of Bologna Observatory. “This small galaxy is unlikely to hold together much longer. It is being pushed and pulled by the colossal gravity of our Milky Way, which has been progressively stealing its stars and pulling it apart.” Some remnants of the Canis Major dwarf form a ring around the disk of the Milky Way.

“The Canis Major dwarf galaxy may have added up to 1% more mass to our Galaxy,” said Dr Geraint Lewis of the University of Sydney. “This is also an important discovery because it highlights that the Milky Way is not in its middle age – it is still forming.” “Past interactions of the sort we are seeing here could be responsible for some of the exquisite detail we see today in the structure of the Galaxy,” says Dr Michael Irwin of the University of Cambridge.

Original Source: RAS News Release

Posted on by Fraser Cain

ESA Watches Earthquakes Shake the Sky

Image credit: ESA

When a powerful earthquake shook the ground in Alaska a year ago, it also set the Earth’s atmosphere shaking. A team of European scientists used the Global Positioning System to map disturbances in the Earth’s ionosphere after a 7.9 magnitude earthquake struck Denali, Alaska. The ionosphere starts at 75 km and goes up to 1,000 km altitude, and it amplifies any disturbance that happens on the ground beneath it – one millimeter disturbance on the ground could become a 100 metre oscillation at 75 km altitude. This gives scientists a new tool to track earthquakes around the world.

A violent earthquake that cracked highways in Alaska set the sky shaking as well as the land, an ESA-backed study has confirmed.

This fact could help improve earthquake detection techniques in areas lacking seismic networks, including the ocean floor.

A team from the Institut de Physique du Globe de Paris and the California Institute of Technology has successfully used the Global Positioning System (GPS) satellite constellation to map disturbances in the ionosphere following last November?s magnitude 7.9 earthquake in Denali, Alaska.

Their paper has been published in the scientific journal Geophysical Research Letters. The research itself was carried out in support of ESA?s Space Weather Applications Pilot Project, aimed at developing operational monitoring systems for space conditions that can influence life here on Earth.

The ionosphere is an atmospheric region filled with charged particles that blankets the Earth between altitudes of about 75 to 1000 km. It has a notable ability to interfere with radio waves propagating through it.

In the particular case of GPS navigational signals, received on Earth from orbiting satellites, fluctuations in the ionosphere ? known as ‘ionospheric scintillations’ – have the potential to cause signal delays, navigation errors or in extreme cases several hours of service lockouts at particular locations.

But while such interference can be an inconvenience for ordinary GPS users, it represents a boon for scientists. By measuring even much smaller-scale shifts in GPS signal propagation time – caused by variations in local electron density as the signal passes through the ionosphere – researchers have at their fingertips a means of mapping ionospheric fluctuations in near real time.

The French and US team made use of dense networks of hundreds of fixed GPS receivers in place across California. These networks were originally established to measure small ground movements due to geological activity, but they can also be utilised to plot the ionosphere structure across three dimensions and in fine detail.

Then when the Denali earthquake occurred on 3 November 2002, the team had a chance to use this technique to investigate another distinctive property of the ionosphere, its ability to work like a natural amplifier of seismic waves moving across the Earth?s surface.

There are several different types of seismic waves moving the ground during an earthquake, the largest scale and the one that does most of the movement is known as a Rayleigh Wave. This type of wave rolls along the ground up and down and side-to-side, in the same way as a wave rolls along the ocean.

Previous research has established that shock waves from Rayleigh Waves in turn set up large-scale disturbances in the ionosphere. A one millimetre peak-to-peak displacement at ground level can set up oscillations larger than 100 metres at an altitude of 150 km.

What the team were able to do following the Denali quake was detect a distinctive wavefront moving through the ionosphere. “Using the network allowed us to observe the propagation of the waves,” explained co-author Vesna Ducic. “We could also separate the small total electron content signal from the very large total electron content variations related to the daily variation of the ionosphere.”

The team observed a signal two to three times larger than the noise level, arriving about 660 to 670 seconds after the arrival of Rayleigh Waves on the ground. And because around six GPS satellites are visible to every ground receiver they were able to calculate the altitude of maximum perturbation ? around 290 to 300 km up.

The signals were weak and only sampled every 30 seconds, with a maximum resolution of 50 km and the overall noise rate high. But the ionospheric signal observed had a clear pattern consistent with models of seismic behaviour. The hope is that the technique can be improved in future, and used to detect earthquakes in areas without seismic detectors, such as the deep ocean or near islands.

“In the framework of Galileo we plan to develop this research,? said Ducic. “Galileo will double the number of satellites and therefore will allow much more precise maps of the ionosphere. We can also foresee that Europe will develop a dense network of Galileo/GPS stations that will take part in the monitoring of these phenomena.

“ESA, together with the French Ministry of Research and CNES have already decided to fund a pre-operational project called SPECTRE – Service and Products for Ionosphere Electronic Content and Tropospheric Refractive index over Europe from GPS – devoted to the high-resolution mapping of the ionosphere. We will be carrying out mapping above Europe as well as California.

“These investigations will support the French space agency CNES?s DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) microsatellite, to be launched in 2004 and devoted to the detection in the ionosphere of seismic, volcanic and man-made signals. These ESA activities will be performed in the framework of the Space Weather Applications Pilot Project.”

The Space Weather Applications Pilot Project is an ESA initiative which has already begun to develop a wide range of application-oriented services based around space weather monitoring.

The co-funded services under development – of which this project is one – also include forecasting disruption to power and communication systems, and the provision of early warning to spacecraft operators of the hazards presented by increased solar and space weather activities. The hope is that an a seismic detection service based on ionospheric measurements may in future supplement existing resources in Europe and elsewhere.

Original Source: ESA News Release

Posted on by Fraser Cain

NASA Orders Pegasus and Taurus Rockets for Future Launches

Image credit: Orbital

NASA has ordered four launch vehicles from Orbital Sciences Corporation, including two Pegasus and two Taurus rockets, for future missions. The Pegasus rockets will launch NASA’s Space Technology-8 and Small Explorer-10 missions. The Taurus rockets will launch the GLORY satellite and the Orbiting Carbon Observer. NASA has been working with Orbital for 12 years and purchased 25 rockets to launch various missions into space.

Orbital Sciences Corporation (NYSE: ORB) announced today that the National Aeronautics and Space Administration (NASA) has ordered four space launch vehicles, including two Pegasus and two Taurus rockets, for U.S. government scientific satellite missions scheduled to be launched over a two-year period beginning in 2006. The orders were placed under the Small Expendable Launch Vehicles Services (SELVS) contract that was awarded to Orbital by NASA’s Kennedy Space Center in 1998.

The two new Pegasus vehicles will be used to launch the satellites designated for NASA’s Space Technology-8 (ST-8) and Small Explorer-10 (SMEX-10) missions. The two Taurus missions are scheduled to launch NASA satellites that Orbital is currently developing and manufacturing at its Dulles, VA facility. The first of the two new Taurus rockets will launch the GLORY satellite for NASA’s Goddard Space Flight Center. The second Taurus rocket will launch the Orbiting Carbon Observer satellite for the Jet Propulsion Laboratory.

With these new launch vehicle orders, NASA is continuing a 12-year relationship with Orbital for Pegasus and derivative rockets, which began in 1991. During this time, the space agency has purchased 25 Pegasus, Taurus and related launch vehicles for a wide range of Earth and space science and technology demonstration missions. Fourteen of these launches have been carried out to date, while another 11 are planned from 2004 to 2008.

“Orbital is very pleased with NASA’s continued commitment to our space launch vehicle products,” said Mr. David W. Thompson, Orbital’s Chairman and Chief Executive Officer. “We look forward to continuing the excellent working relationship that our launch vehicle team has established with its NASA counterparts. Together, our shared goal is to reliably support the scientific community’s use of small satellites for highly productive Earth and space science investigations.”

About the Pegasus Launch System
Pegasus is the world’s leading launch system for the deployment of small satellites weighing up to 1,000 pounds into low-Earth orbit. Its patented air-launch system, in which the rocket is launched from beneath Orbital’s “Stargazer” L-1011 carrier aircraft over the ocean, reduces cost and provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements.

First launched in 1990, Pegasus is the world’s only small launch vehicle to have earned NASA’s Category-3 certification, which allows the U.S. space agency to launch its most valuable payloads aboard the rocket. A Category-3 certification is achieved through a long-term record of highly reliable launch services, such as the current record of 21 consecutive successful Pegasus missions carried out since 1997.

About the Taurus Launch System
Orbital developed the ground-launched Taurus vehicle to provide a cost-effective, reliable means of launching satellites weighing up to 3,000 pounds into low-Earth orbit. First launched in 1994, Taurus incorporates advanced structural and avionics technology proven on Pegasus and other operational launch systems and is designed for easy transportability, offering customers rapid-response launches from a wide range of locations.

About Orbital
Orbital develops and manufactures small space systems for commercial, civil government and military customers. The company’s primary products are satellites and launch vehicles, including low-orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters that are used as interceptor and target vehicles. Orbital also offers space-related technical services to government agencies and develops and builds satellite-based transportation management systems for public transit agencies and private vehicle fleet operators.

Original Source: Orbital News Release