Posted on by Fraser Cain

Radio Telescopes Will Contribute to Huygens’ Mission

When the European Space Agency’s Huygens spacecraft makes its plunge into the atmosphere of Saturn’s moon Titan on January 14, radio telescopes of the National Science Foundation’s National Radio Astronomy Observatory (NRAO) will help international teams of scientists extract the maximum possible amount of irreplaceable information from an experiment unique in human history. Huygens is the 700-pound probe that has accompanied the larger Cassini spacecraft on a mission to thoroughly explore Saturn, its rings and its numerous moons.

The Robert C. Byrd Green Bank Telescope (GBT) in West Virginia and eight of the ten telescopes of the continent-wide Very Long Baseline Array (VLBA), located at Pie Town and Los Alamos, NM, Fort Davis, TX, North Liberty, IA, Kitt Peak, AZ, Brewster, WA, Owens Valley, CA, and Mauna Kea, HI, will directly receive the faint signal from Huygens during its descent.

Along with other radio telescopes in Australia, Japan, and China, the NRAO facilities will add significantly to the information about Titan and its atmosphere that will be gained from the Huygens mission. A European-led team will use the radio telescopes to make extremely precise measurements of the probe’s position during its descent, while a U.S.-led team will concentrate on gathering measurements of the probe’s descent speed and the direction of its motion. The radio-telescope measurements will provide data vital to gaining a full understanding of the winds that Huygens encounters in Titan’s atmosphere.

Currently, scientists know little about Titan’s winds. Data from the Voyager I spacecraft’s 1980 flyby indicated that east-west winds may reach 225 mph or more. North-south winds and possible vertical winds, while probably much weaker, may still be significant. There are competing theoretical models of Titan’s winds, and the overall picture is best summarized as poorly understood. Predictions of where the Huygens probe will land range from nearly 250 miles east to nearly 125 miles west of the point where its parachute first deploys, depending on which wind model is used. What actually happens to the probe as it makes its parachute descent through Titan’s atmosphere will give scientists their best-ever opportunity to learn about Titan’s winds.

During its descent, Huygens will transmit data from its onboard sensors to Cassini, the “mother ship” that brought it to Titan. Cassini will then relay the data back to Earth. However, the large radio telescopes will be able to receive the faint (10-watt) signal from Huygens directly, even at a distance of nearly 750 million miles. This will not be done to duplicate the data collection, but to generate new data about Huygens’ position and motions through direct measurement.

Measurements of the Doppler shift in the frequency of Huygens’ radio signal made from the Cassini spacecraft, in an experiment led by Mike Bird of the University of Bonn, will largely give information about the speed of Titan’s east-west winds. A team led by scientists at NASA’s Jet Propulsion Laboratory in Pasadena, CA, will measure the Doppler shift in the probe’s signal relative to Earth. These additional Doppler measurements from the Earth-based radio telescopes will provide important data needed to learn about the north-south winds.

“Adding the ground-based telescopes to the experiment will not only help confirm the data we get from the Cassini orbiter but also will allow us to get a much more complete picture of the winds on Titan,” said William Folkner, a JPL scientist.

Another team, led by scientists from the Joint Institute for Very Long Baseline Interferometry in Europe (JIVE), in Dwingeloo, The Netherlands, will use a world-wide network of radio telescopes, including the NRAO telescopes, to track the probe’s trajectory with unprecedented accuracy. They expect to measure the probe’s position within two-thirds of a mile (1 kilometer) at a distance of nearly 750 million miles.

“That’s like being able to sit in your back yard and watch the ball in a ping-pong game being played on the Moon,” said Leonid Gurvits of JIVE.

Both the JPL and JIVE teams will record the data collected by the radio telescopes and process it later. In the case of the Doppler measurements, some real-time information may be available, depending on the strength of the signal, but the scientists on this team also plan to do their detailed analysis on recorded data.

The JPL team is utilizing special instrumentation from the Deep Space Network called Radio Science Receivers. One will be loaned to the GBT and another to the Parkes radio observatory. “This is the same instrument that allowed us to support the challenging communications during the landing of the Spirit and Opportunity Mars rovers as well as the Cassini Saturn Orbit Insertion when the received radio signal was very weak,” said Sami Asmar, the JPL scientist responsible for the data recording.

When the Galileo spacecraft’s probe entered Jupiter’s atmosphere in 1995, a JPL team used the NSF’s Very Large Array (VLA) radio telescope in New Mexico to directly track the probe’s signal. Adding the data from the VLA to that experiment dramatically improved the accuracy of the wind-speed measurements.

“The Galileo probe gave us a surprise. Contrary to some predictions, we learned that Jupiter’s winds got stronger as we went deeper into its atmosphere. That tells us that those deeper winds are not driven entirely by sunlight, but also by heat coming up from the planet’s core. If we get lucky at Titan, we’ll get surprises there, too,” said Robert Preston, another JPL scientist.

The Huygens probe is a spacecraft built by the European Space Agency (ESA). In addition to the NRAO telescopes, the JPL Doppler Wind Experiment will use the Australia Telescope National Facility and other radio telescopes in Parkes, Mopra, and Ceduna, Australia; Hobart, Tasmania; Urumqi and Shanghai, China; and Kashima, Japan. The positional measurements are a project led by JIVE and involving ESA, the Netherlands Foundation for Research in Astronomy, the University of Bonn, Helsinki University of Technology, JPL, the Australia Telescope National Facility, the National Astronomical Observatories of China, the Shanghai Astronomical Observatory, and the National Institute for Communication Technologies in Kashima, Japan.

The Joint Institute for VLBI in Europe is funded by the national research councils, national facilities and institutes of The Netherlands (NWO and ASTRON), the United Kingdom (PPARC), Italy (CNR), Sweden (Onsala Space Observatory, National Facility), Spain (IGN) and Germany (MPIfR). The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Original Source: NRAO News Release

Posted on by Fraser Cain

Experiments Chosen For Lunar Orbiter

NASA has selected six proposals to provide instrumentation and associated exploration/science measurement investigations for the Lunar Reconnaissance Orbiter (LRO), the first spacecraft to be built as part of the Vision for Space Exploration.

The LRO mission is scheduled to launch in the fall of 2008 as part of NASA’s Robotic Lunar Exploration Program. The mission will deliver a powerful orbiter to the vicinity of the moon to obtain measurements necessary to characterize future robotic and human landing sites. It also will identify potential lunar resources and document aspects of the lunar radiation environment relevant to human biological responses.

Proposals were submitted to NASA in response to an Announcement of Opportunity released in June 2004. Instrumentation provided by these selected measurement investigations will be the payload of the mission scheduled to launch in October 2008.

“The payload we have selected for LRO builds on our collective experience in remote sensing of the Earth and Mars,” said NASA’s Deputy Associate Administrator for the Science Mission Directorate, Dr. Ghassem Asrar. “The measurements obtained by these instruments will characterize in unprecedented ways the moon’s surface and environment for return of humans in the next decade,” he added.

“LRO will deliver measurements that will be critical to the key decisions we must make before the end of this decade,” said NASA’s Associate Administrator for the Exploration Systems Mission Directorate, Craig Steidle. “We are extremely excited by this innovative payload, and we are confident it will fulfill our expectations and support the Vision for Space Exploration,” Steidle added.

“The instruments selected for LRO represent an ideal example of a dual use payload in which exploration relevance and potential scientific impact are jointly maximized,” NASA’s Chief Scientist, Dr. Jim Garvin said. “I am confident LRO will discover a ‘new moon’ for us, and in doing so shape our human exploration agenda for our nearest planetary neighbor for decades to come,” he said.

The selected proposals will conduct Phase A/B studies to focus on how proposed hardware can best be accommodated, completed, and delivered on a schedule consistent with the mission timeline. An Instrument Preliminary Design Review and Confirmation for Phase C Review will be held at the completion of Phase B.

Selected investigations and principal investigators:

“Lunar Orbiter Laser Altimeter (LOLA) Measurement Investigation” – principal investigator Dr. David E. Smith, NASA Goddard Space Flight Center (GSFC), Greenbelt, Md. LOLA will determine the global topography of the lunar surface at high resolution, measure landing site slopes and search for polar ices in shadowed regions.

“Lunar Reconnaissance Orbiter Camera” (LROC) – principal investigator Dr. Mark Robinson, Northwestern University, Evanston, Ill. LROC will acquire targeted images of the lunar surface capable of resolving small-scale features that could be landing site hazards, as well as wide-angle images at multiple wavelengths of the lunar poles to document changing illumination conditions and potential resources.

“Lunar Exploration Neutron Detector” (LEND) – principal investigator Dr. Igor Mitrofanov, Institute for Space Research, and Federal Space Agency, Moscow. LEND will map the flux of neutrons from the lunar surface to search for evidence of water ice and provide measurements of the space radiation environment which can be useful for future human exploration.

“Diviner Lunar Radiometer Experiment” – principal investigator Prof. David Paige, UCLA, Los Angeles. Diviner will map the temperature of the entire lunar surface at 300 meter horizontal scales to identify cold-traps and potential ice deposits.

“Lyman-Alpha Mapping Project” (LAMP) – principal investigator Dr. Alan Stern, Southwest Research Institute, Boulder, Colo. LAMP will observe the entire lunar surface in the far ultraviolet. LAMP will search for surface ices and frosts in the polar regions and provide images of permanently shadowed regions illuminated only by starlight.

“Cosmic Ray Telescope for the Effects of Radiation” (CRaTER) – principal investigator Prof. Harlan Spence, Boston University, Mass. CRaTER will investigate the effect of galactic cosmic rays on tissue-equivalent plastics as a constraint on models of biological response to background space radiation.

The LRO project is managed by GSFC. Goddard will acquire the launch system and spacecraft, provide payload accommodations, mission systems engineering, assurance, and management. For information about NASA and agency programs on the Internet, visit:

http://www.nasa.gov

Original Source: NASA News Release

Posted on by Fraser Cain

Massive Galaxies are Still Forming

NASA’s Galaxy Evolution Explorer has spotted what appear to be massive “baby” galaxies in our corner of the universe. Previously, astronomers thought the universe’s birth rate had dramatically declined and only small galaxies were forming.

“We knew there were really massive young galaxies eons ago, but we thought they had all matured into older ones more like our Milky Way. If these galaxies are indeed newly formed, then this implies parts of the universe are still hotbeds of galaxy birth,” said Dr. Chris Martin. He is principal investigator for the Galaxy Evolution Explorer at the California Institute of Technology, Pasadena, Calif., and co-author of the study.

Martin and colleagues, led by Dr. Tim Heckman of Johns Hopkins University, Baltimore, Md., unearthed three-dozen bright, compact galaxies that greatly resemble the youthful galaxies of more than 10 billions years ago. These new galaxies are relatively close to us, ranging from two to four billion light-years away. They may be as young as 100 million to one billion years old. The Milky Way is approximately 10 billion years old.

The recent discovery suggests our aging universe is still alive with youth. It also offers astronomers their first, close-up glimpse at what our galaxy probably looked like when it was in its infancy.

“Now we can study the ancestors to galaxies much like our Milky Way in much more detail than ever before,” Heckman said. “It’s like finding a living fossil in your own backyard. We thought this type of galaxy had gone extinct, but in fact newborn galaxies are alive and well in the universe,” he added.

The new discoveries are of a type called ultraviolet luminous galaxies. They were discovered after the Galaxy Evolution Explorer scanned a large portion of the sky with its highly sensitive ultraviolet light detectors. Since young stars pack most of their light into ultraviolet wavelengths, young galaxies appear to the spacecraft like diamonds in a field of stones. Astronomers mined for these rare gems before, but missed them because they weren’t able to examine a large enough slice of the sky.

“The Galaxy Evolution Explorer surveyed thousands of galaxies before finding these few dozen ultraviolet-bright ones,” said Dr. Michael Rich, a co-author of the study from the University of California, Los Angeles.

The newfound galaxies are about 10 times as bright in ultraviolet wavelengths as the Milky Way. This indicates they are teeming with violent star-forming regions and exploding supernova, which are characteristics of youth.

When our universe was young, massive galaxies were regularly bursting into existence. Over time, the universe bore fewer and fewer galactic progeny, and its newborn galaxies grew up into ones that look like our own. Until now, astronomers thought they had seen the last of these giant babies.

The results will be published in an upcoming special issue of Astrophysical Journal Letters, along with several other papers describing new results from the Galaxy Evolution Explorer.

The Galaxy Evolution Explorer was launched on April 28, 2003. Its mission is to study the shape, brightness, size and distance of galaxies across 10 billion years of cosmic history. The Explorer’s 50-centimeter-diameter (19.7-inch) telescope sweeps the skies in search of ultraviolet-light sources.

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the mission and built the science instrument. The mission was developed under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. South Korea and France are the international partners in the mission.

For images and information about the Galaxy Evolution Explorer on the Internet, visit http://www.nasa.gov/centers/jpl/missions/galex.html. For information about NASA and agency programs on the Internet, visit http://www.nasa.gov.

Original Source: NASA News Release

Posted on by Fraser Cain

Huygens Ready for Release

The highlights of the first year of the Cassini-Huygens mission to Saturn can be broken into two chapters: first, the arrival of the Cassini orbiter at Saturn in June, and second, the release of the Huygens probe on Dec. 24, 2004, on a path toward Titan.

Artist’s concept of Cassini releasing the Huygens probe to Titan.
The Huygens probe, built and managed by the European Space Agency (ESA), is bolted to Cassini and fed electrical power through an umbilical cable. It has been riding along during the nearly seven-year journey to Saturn largely in a “sleep” mode, awakened every six months for three-hour instrument and engineering checkups. In three days, it will be cut loose from its mother ship and will coast toward Saturn’s moon Titan, arriving on Jan. 14, 2005.

“As partners with ESA, one of our obligations was to carry the Huygens probe to Saturn and drop it off at Titan,” said Robert T. Mitchell, Cassini program manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We’ve done the first part, and on Christmas Eve we will release Huygens and tension-loaded springs will gently push it away from Cassini onto a ballistic free-fall path to Titan.”

Once freed from Cassini, the Huygens probe will remain dormant until the onboard timer wakes it up shortly before the probe reaches Titan’s upper atmosphere on Jan. 14. Then it will begin a dramatic plunge through Titan’s murky atmosphere, tasting the chemical makeup and composition as it descends to touch down on its surface. The data gathered during this 2-1/2 hour descent will be transmitted from the probe to the Cassini orbiter. Afterward, Cassini will point its antenna to Earth and relay the data through NASA’s Deep Space Network to JPL and on to ESA’s Space Operations Center in Darmstadt, Germany, which serves as the operations center for the Huygens probe mission. From this control center, ESA engineers will be tracking the probe and scientists will be standing by to process the data from the probe’s six instruments.

Currently, both the orbiter and the probe are on an impact trajectory with Titan. This is the only way to ensure that Cassini delivers the probe in the right location. A confirmation of successful release is expected to be received from NASA’s Deep Space Network tracking stations at Madrid, Spain and Goldstone, Calif., shortly before 8:00 p.m. PST on Dec. 24. A team of JPL engineers and ESA mission managers will be monitoring spacecraft activities at JPL during the release phase of the mission.

On Dec. 27, the Cassini orbiter will perform a deflection maneuver to keep it from following Huygens into Titan’s atmosphere. This maneuver will also establish the required geometry between the probe and the orbiter for radio communications during the probe descent.

Two of the instruments on ESA’s Huygens probe, the descent imager and spectral radiometer camera and the gas chromatograph-mass spectrometer, are contributions from NASA and American academia.

The imaging camera will take advantage of the Huygens probe’s rotation, using two imagers to observe the surface of Titan during the late stages of descent for a view of the regions around the impact site. A side-looking imager will view the horizon and the underside of any cloud deck. More than just a camera, the instrument is designed to measure concentrations of argon and methane in the atmosphere and determine the size and density of particles. The instrument will also determine if the local surface is a solid or liquid, and if solid, its topography. The principal investigator is Dr. Martin G. Tomasko of the University of Arizona, Tucson, Ariz.

Although Titan’s atmosphere is primarily nitrogen and methane, scientists believe it contains many other gases that are present only in small amounts. These trace gases can reveal critical details about the origin and evolution of Titan’s atmosphere. Because trace gases are rare, they are difficult or impossible to observe remotely, so direct measurements must be made.

The gas chromatograph-mass spectrometer instrument will sample gas directly from Titan’s atmosphere as the Huygens probe descends by parachute. Data from the instrument will allow researchers to investigate the chemical composition, origin and evolution of the atmosphere of Titan. The instrument was designed and built by NASA’s Goddard Space Flight Center, Greenbelt, Md., and is led by the principal investigator, Dr. Hasso Niemann.

Updates on the Huygens probe release will be available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini . The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter. The European Space Agency built and managed the development of the Huygens probe and is in charge of the probe operations. The Italian Space Agency provided the high-gain antenna, much of the radio system and elements of several of Cassini’s science instruments.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Delta 4 Heavy Launches, But Falls Short

The Boeing [NYSE: BA] Delta IV Heavy made its first flight today achieving the major test objectives despite placing its demonstration satellite in a lower than expected orbit.

The Delta IV Heavy lifted off from Space Launch Complex 37B, Cape Canaveral Air Force Station, Fla., at 4:50 p.m. EST, on a demonstration launch for the Air Force’s Evolved Expendable Launch Vehicle (EELV) program. The demonstration satellite was deployed following a 5-hour and 50-minute flight.

?The EELV program and Boeing invested in today’s demonstration launch to ensure that the Delta IV Heavy, the only EELV Heavy variant available, is ready to launch our nation’s most important national security payloads into space,? said Dan Collins, vice president of Boeing Expendable Launch Systems. ?While the demonstration satellite did not reach its intended orbit, we now have enough information and confidence in the Delta IV Heavy to move forward with preparations for the upcoming Defense Support Program launch in 2005.?

A preliminary review of the data indicates that a shorter than expected first-stage burn led to the low orbit. However, according to the Air Force EELV program office, the primary flight objectives were accomplished in today’s all-up test of the new launch vehicle. The heavy boost phase, the new five-meter upper stage and five-meter payload fairing, extended coast, upper stage third burn and payload separation, and activation and usage of Space Launch Complex 37B for a Heavy launch were all successfully demonstrated.

?I want to thank our entire Delta team, including our government and industry partners,? Collins said. ?Their efforts, hard work and focus have once again moved our industry forward. We have a very happy and confident customer, thanks to all the hard work put in by this team.?

A unit of The Boeing Company, Boeing Integrated Defense Systems is one of the world’s largest space and defense businesses. Headquartered in St. Louis, Boeing Integrated Defense Systems is a $27 billion business. It provides network-centric system solutions to its global military, government, and commercial customers. It is a leading provider of intelligence, surveillance and reconnaissance systems; the world’s largest military aircraft manufacturer; the world’s largest satellite manufacturer and a leading provider of space-based communications; the primary systems integrator for U.S. missile defense and Department of Homeland Security; NASA’s largest contractor; and a global leader in launch services.

Original Source: Boeing News Release

Posted on by Fraser Cain

Mediterranean Heat Map Produced from Space

Image credit: ESA
This ultra high-resolution sea surface temperature map of the Mediterranean could only have been made with satellites. Any equivalent ground-based map would need almost a million and a half thermometers placed into the water simultaneously, one for every two square kilometres of sea.

This most detailed ever heat map of all 2 965 500 square kilometres of the Mediterranean, the world’s largest inland sea is being updated on a daily basis as part of ESA’s Medspiration project.

With sea surface temperature (SST) an important variable for weather forecasting and increasingly seen as a key indicator of climate change, the idea behind Medspiration is to combine data from multiple satellite systems to produce a robust set of sea surface data for assimilation into ocean forecasting models of the waters around Europe and also the whole of the Atlantic Ocean.

For the Mediterranean Sea, the Medspiration product is being created to an unprecedented spatial resolution of two square kilometres, as Ian Robinson of the Southampton Oceanography Centre, managing the Medspiration Project explains: “The surface temperature distribution in the Mediterranean contains many finely detailed features that reveal eddies, fronts and plumes associated with the dynamics of water circulation. A resolution as fine as this is needed to allow these features to be properly tracked.”

The remaining ocean products are intended to have a still impressive spatial resolution of ten square kilometres. Overall results from the Medspiration project also feed into an even more ambitious scheme to combine all available SST data into a worldwide high-resolution product, known as the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea Surface Temperature Pilot Project (GHRSST-PP).

Its aim is to deliver to the user community a new generation of highly accurate worldwide SST products with a space resolution of less than ten kilometres every six hours.

As an important step towards achieving this goal, ESA has not only initiated Medspiration as the European contribution to the overall GHRSST-PP effort, but the Agency funded a GHRSST International Project Office, located at the Hadley Centre for Climate Prediction and Research, a part of the UK Met Office located in Exeter.

“Medspiration is at the forefront of the GHRSST-PP effort and is driving the operational demonstration of GHRSST-PP as an international system,” says Craig Donlon, head of the GHRSST Office. “GHRSST has developed with a ‘system of systems’ approach, demanding stable interfaces and comprehensive data handling and processing systems.

“Medspiration is ready to deliver the European component of GHRSST-PP. Over the next 12 months Medspiration will play a fundamental role in partnership with other operational groups in the USA, Australia and Japan as the GHRSST-PP system begins the operational delivery of a new generation of SST data products to European and international user communities in near real time.”

The temperature of the surface of the ocean is an important physical property that strongly influences the transfer of heat energy, momentum, water vapour and gases between the ocean and the atmosphere.

And because water takes a long time to warm up or cool down the sea surface functions as an enormous reservoir of heat: the top two metres of ocean alone store all the equivalent energy contained in the atmosphere.

The whole of their waters store more than a thousand times this same value ? climatologists sometimes refer to the oceans as the ‘memory’ of the Earth’s climate, and measuring SST on a long-term basis is the most reliable way to establish the rate of global warming.

Like thermometers in the sky, a number of different satellites measure SST on an ongoing basis. For example, the Advanced Along-Track Scanning Radiometer (AATSR) aboard ESA’s Envisat uses infrared wavelengths to acquire SST for a square kilometre of ocean to an accuracy of 0.2 ?C. In fact, thanks to its high accuracy, AATSR is helping to calibrate other sensors employed by the Medspiration project.

Other satellites may have decreased accuracy or resolution, but potentially make up for it with cloud-piercing microwave abilities or much larger measuring ‘footprints’. Combine all available satellite data together ? along with localised measurements from buoys and research ships – and you can achieve daily monitoring of the temperature of all the oceans covering 71% of the Earth’s surface. This information is then prepared for input into the relevant ‘virtual ocean’ ? a sophisticated computer model of the genuine article.

The combination of satellite and also available in-situ observations with numerical modelling ? a technique known as ‘data assimilation’ ? is an extremely powerful one. It has revolutionised atmospheric weather forecasting and is now being applied to the oceans.

Near real time observational inputs keep an ocean model from diverting too much from reality, while the outputs from the model make up for any gaps in coverage. With maximised coupling between actual observations and the numerical model, output data can be credibly used for operational tasks such as sea state and algal bloom forecasting, and predicting the path of oil spills. And these models can also be used to look deeper than just the ocean surface.

“The time is coming for operational monitoring and forecasting of three-dimensional global ocean structure,” comments Jean-Louis Fellous, Director for Ocean Research at France’s IFREMER, the French Research Institute for Exploitation of the Sea, a Medspiration project partner. “A project like Medspiration is a key contribution to this endeavour.

“With the capabilities offered by spaceborne SST sensors, by satellite altimeters and by the 1,500 profiling floats measuring temperature and salinity in the deep ocean ? and all this data being fed in near-real time to global ocean models, this vision is becoming a reality.”

Although the new map of the Mediterranean represents an important step forward, both Medspiration and GODAE GHRSST-PP remain works in progress at this point.

The main problem with monitoring high-resolution SST of the Mediterranean is cloud cover. To compensate the team has available a near real time data stream from four separate satellites ? two European, one American and one Japanese. Also applied is a technique called ‘objective analysis’ that minimises cloud effects by interpolating values from just outside the obscured area or from that area measured at times before or after cloud covered it.

Mixing satellite data together on a routine basis is fraught with difficulty because the thermal structure of the upper ocean is actually extremely complex, and different sensors may be measuring different values. There is also considerable day-to-night variability, with daytime temperatures varying with depth much more than those during the night.

Part of the aim of Medspiration is to fully account for this diurnal cycle, in order to improve the overall effectiveness of its data assimilation into ocean forecasting models.

Original Source: ESA News Release

Posted on by Fraser Cain

High Bandwidth Communications With Mars

It would be a planetary scientist?s dream to peer through the eyes of a distant rover?s lenses in real-time, looking around an alien landscape as if she were actually on the planet?s surface, but current radio transmitters can?t handle the bandwidth necessary for a video feed across several million miles. New technology recently patented by scientists at the University of Rochester, however, may make applications like a Mars video feed possible, using lasers instead of radio technology. Special gratings inside the glass of a fiber laser virtually eliminate detrimental scattering, the main hurdle in the quest for high-powered fiber lasers.

?We use lasers in everything from telecommunications to advanced weaponry, but when we need a high-powered laser, we had to fall back on old, inefficient methods,? says Govind Agrawal, professor of optics at the University of Rochester. ?We?ve now shown an incredibly simple way to make high-power fiber lasers, which have enormous potential.?

By removing one of the main limitations of fiber lasers and fiber amplifiers, Agrawal has allowed them to replace traditionally more powerful, but less efficient and poorer quality, traditional lasers. Currently, industries use carbon dioxide and diode-pumped solid-state crystal lasers for welding or cutting metal and machining tiny parts, but these kinds of lasers are bulky and hard to cool. In contrast, the newest alternative, fiber lasers, are efficient, easy to cool, more compact, and more precise. The problem with fiber lasers, however, is that as their wattage increases, the fiber itself begins to create a backlash that effectively shuts down the laser.

Agrawal worked on a way to eliminate the backlash caused by a condition called stimulated Brillouin scattering. When light of high enough power travels down a fiber, the light itself changes the composition of the fiber. The light waves cause areas of the glass fiber to become more and less dense, much as a traveling caterpillar scrunches up and expands its body as it moves along. As the laser light passes from an area of high density to one of low density, it is diffracted the same way the image of a straw bends as it passes between the air and water in a glass. As the power of the laser increases, the diffraction increases until it is reflecting much of the laser light backward, toward the laser itself, instead of properly down the fiber.

In a discussion with, Hojoon Lee, a visiting professor from Korea, Agrawal wondered if gratings etched inside the fiber might help stop the reflection problem. The gratings can be designed to act as a kind of two-way mirror, working almost exactly the same way as the initial problem, only reflecting light forward instead of backward. With the new, simple design, the laser light fires down the fiber through the gratings, and some of it again creates the density changes that reflect some of the light backward?but this time the series of gratings simply bounces that backward reflection forward again. The net result is that the fiber laser can deliver higher wattages than ever before, rivaling conventional lasers and making possible applications that conventional lasers cannot perform, such as high-bandwidth laser communication with a planetary rover several million miles away.

As a laser beam travels between planets, it spreads out and diffracts so much that by the time a beam from Mars reaches us, its width would be larger than 500 miles, making it incredibly difficult to extract the information encoded on the beam. A fiber laser, with its ability to deliver more power, would help by giving receiving stations a more intense signal to work with. In addition, Agrawal is now working with NASA to develop a laser communications system that would spread less to begin with. ?It?s our hope that instead of having a beam that spreads out 500 miles, maybe we can get one that only spreads out a mile or so,? says Agrawal. That concentration of the laser?s power would make it much easier for us to receive high-bandwidth signals from a distant rover.

Many people are using fiber lasers to replace conventional lasers, from the military to the University of Rochester?s own Omega laser in the Laboratory for Laser Energetics (LLE), which is the most powerful ultraviolet laser in the world. Agrawal will be working with scientists at LLE to possibly implement the new grating system into the Omega?s new fiber laser system.

Original Source: University of Rochester News Release

Posted on by Fraser Cain

Ariane Lofts 7 Satellites at Once

Arianespace has successfully launched the Helios IIA observation satellite for the French, Belgian and Spanish ministries of defense.

Following a flight lasting 60 minutes and 8 seconds, the Ariane 5 launch vehicle accurately injected Helios IIA into Sun-synchronous polar orbit. The mission also deployed six auxiliary payloads: four Essaim micro-satellites and two other small spacecraft, Parasol and Nanosat.

Sixteenth successful launch
With its 16th successful mission, the standard Ariane 5G (“Generic”) launcher continues to confirm its technical and operational maturity. The launcher also showed its ability to handle a complete range of missions, from government launches into Sun-synchronous orbit to huge commercial satellites into geostationary orbit and scientific spacecraft into special orbits.

The launch was from Europe’s Spaceport in Kourou, French Guiana, on Saturday, December 18, at 1:26 p.m. local time in Kourou (1626 GMT, and 5:26 pm in Paris).

A Boost for Defense
The Ariane 5 launcher is a key to the development of a common European defense and security policy, which must include space capability. Helios IIA is the 23rd military payload to be carried by Europe’s Ariane launcher.

Arianespace covers the spectrum of missions needed by European armed forces:

# Optical observation, including launches of Helios 1A in July 1995 and Helios 1B in December 1999 (for France, Italy, Spain).
# Telecommunications, with Syracuse I, II and II (France), Sicral 1 (Italy), Skynet 4 (U.K.), Hispasat 1A and 1B (Spain), Turksat 1A, 1B, 1C and Eurasiasat (Turkey).

Helios IIA
Helios IIA is the initial satellite in France’s second-generation defense and security spaceborne observation system, being conducted in conjunction with Belgium and Spain. France’s DGA defense procurement agency (D?l?gation G?n?rale pour l’Armement), which is part of the French MoD, is in charge of the program. It has assigned overall responsibility for the space segment to the French space agency, CNES (Centre National d’Etudes Spatiales).

Helios IIA weighed approximately 4,200 kg. at launch. It was built by EADS Astrium as prime contractor, leading a large team of European subcontractors, including Alcatel Space, in charge of the high resolution imaging instrument.

Essaim
The Essaim program is designed to demonstrate the feasibility of space-based detection of electromagnetic transmitters, and evaluate the performance of this type of system. EADS Astrium is prime contractor for the Essaim program.

Parasol
The Parasol microsat aims to characterize the radiation and microphysical properties of clouds and aerosols. French space agency CNES is prime contractor for the Parasol microsat.

Nanosat
Nanosat will provide an in-orbit demonstration of several telecommunications nano-technologies, as well as solar and magnetic sensors. It was developed and built by INTA of Spain.

Original Source: Arianespace News Release

Posted on by Fraser Cain

What’s Up This Week – Dec 20 – Dec 26, 2004

Image credit: NOAO
Season’s Greetings, fellow SkyWatchers! Take the time from your busy holiday schedule to relax with some astronomy. There will be three minor meteor showers this week: the Coma Berenicids, Delta Arietid and the Ursids. The waxing Moon will become our guide as we locate historic variable Mira. Mare Humorum and Crater Gassendi are great features to learn about on the lunar surface and we’ll travel to the outer arm of our own galaxy to study a multiple star system – Sigma Orionis. Not enough? Then I have a special and very challenging surprise for you on Christmas Day! Although the Moon goes full during this seven-day period, those who are just beginning with new telescopes will appreciate its presence as an easy “pointer” to Saturn. So lift your eyes toward the heavens and enjoy the bright stars of Winter…

Because here’s what’s up!

Monday, December 20 – If you’re up early this morning, take a few minutes to watch the skies for the peak of the Coma Berenicid meteor shower. Although the activity for this one is fairly weak, with an average fall rate of about seven per hour, it still warrants study.

So what makes this particular shower of interest? Noted first in 1959, the stream was eventually tied in 1973 to another minor shower bearing the same orbit known as the December Leo Minorids. As we know, meteoroid streams are traditionally tied to the orbit of a comet, and in this case the comet was unconfirmed! Observed in 1912 by B. Lowe, an Australian amateur astronomer, the comet was officially designated as 1913 I and was only seen four times before losing it to sunrise. Using Lowe’s observations, independent researchers computed the comet’s orbit and it was basically forgotten about until 1954. At that time, Fred Whipple was studying meteoroid orbits and made the association between his photographic studies and the enigmatic comet Lowe. By continuing to observe the annual shower, it was derived that the orbital period of the comet was about 75 years, but the two major streams occurred about 27 and 157 years apart. Thanks to the uneven dispersion of material, it may be another decade before we see some real activity from this shower, but even one meteor can make your day!

And if you want to make your “night” an early one, why not trying looking for another odd meteor shower? Tonight will be the peak of the Delta Arietids! These unusual meteors also bear a resemblance to last week’s Geminids, for the source of the stream appears to be a sun-grazing asteroid named Icarus. The hourly fall rate will be about 12 fast and bright “shooting stars”, but the Moon will interfere since it is so close to the radiant. Be sure to watch early as the constellation of Aries will be in the best position for only a few hours after dark. Have a telescope? Then be sure to visit with Madam Selene while out, because the “Straight Wall” will be making its one night stand parallel to the terminator. Look for its thread-thin black shadow just north of the emerging Tycho.

Tuesday, December 21 – This morning marks the point of winter solstice for the northern hemisphere – the time of year where the Sun appears furthest south. For parents, educators or just those who appreciate physically observing the wonders of astronomy, today would be a good time to start a very simple – and very pleasing – experiment. By placing a stake into the ground, or using a stationery object like a fence or sign post, measure the length of the shadow at noon. Write down your measurements, or cut and tag a piece of string with the date. Around every two weeks or so, repeat the process and enjoy the results!

Mira, Mira on the wall… Who’s the strangest star of all? You are, Omicron Ceti. Tonight we’re going to use the nine day old Moon to help guide us to one of the most interesting stars in the sky – Mira! Over 400 years ago, David Fabricus identified Mira, a.k.a. “the Beautiful One”, to be the very first variable star. But what exactly is it? At the time of its discovery, it was thought to be a nova. Cataloged by Bayer seven years later as 4th magnitude Omicron Ceti, imagine the surprise as it “disappeared” from unaided eye visibility! At minimum Mira is around magnitude 9, but within 331 days can flux as high as 3rd or 4th magnitude and has been known to even reach the brightness of Aldeberan.

As a binary system, Mira A is a red giant that goes through some intense changes during its cycle. As one of the coolest of the red stars at minimum, its hot, blue, sub-dwarf companion actually has twice the mass of the primary star. Is it possible that this tiny companion’s extreme gravitation and heat could affect Mira? As Omicron continues to deplete its hydrogen, the interior “pulses” causing it to become more than 100 times brighter and expand more than 700 times the size of our own Sun. In late 1997, Mira became the second star to be resolved by the Hubble Space Telescope and showed a very strange extension towards its companion star.

So how bright will it be tonight? Ah, my friends… That is the joy of discovery!

Wednesday, December 22 – Up early? Fantastic! In the pre-dawn hours of this morning, we have two treats for you – the return of Mercury and the Ursid meteor shower! Cruising around the Sun about every thirteen and a half years, Comet 8P/Tuttle sheds a little skin. Although it never passes inside of Earth’s orbit, some six years later we pass through its debris stream. Not so unusual? Then think again, because it takes as much as six centuries before the meteoroid trail is effected enough by Jupiter’s gravitation to pass into our atmosphere.

Although the Moon will interfere with watching this circumpolar meteor shower, the hours before dawn could see activity of up to 12 per hour. By keeping watch on the constellation of Ursa Major, you just might spot one of these slow moving, 600 year old travelers that make their path only halfway between us and the Moon!

Before dawn this morning, take a look down low on the horizon and say welcome back to Mercury. Above it, and leading the way is bright Venus. For telescopic observers, the real treat will be to see how differently each planet is phased. Venus will appear highly gibbous, while Mercury will only be about one-third illuminated. Keep watch on this pair in the days ahead as they swap places in the sky!

Thursday, December 23 – Tonight exploring the Moon will be in order as one of the most graceful and recognizable lunar features will be prominent – Gassendi. As an ancient mountain walled plane that sits proudly at the northern edge of Mare Humorum, Gassendi sports a bright ring and a triple central mountain peak that are within the range of binoculars. Telescopic viewers will appreciate Gassendi at high power to view how its southern border has been eroded by lava flow and the many riles and ridges that exist inside the crater and the presence of the younger Gassendi A on north wall. While viewing the Mare Humorum area, keep in mind that we are looking at an area about the size of the state of Arkansas. It is believed that a planetoid collision originally formed Mare Humorum. The incredible impact crushed the surface layers of the Moon resulting in a concentric “anticline” that can be traced twice the size of the original impact area. The floor of this huge crater then filled in with lava and was once thought to have a greenish appearance but in recent years have more accurately been described as reddish. That’s one mighty big crater!

Friday, December 24 – Twas the night before Christmas and all through the house, not a creature was stirring… Except for the mouse with the telescope who wants to see a multiple star system! Why don’t we join him tonight and have a look at a very nice and easily resolved, Sigma Orionis.

This particular system is easily found without a map. By identifying the three “belt” stars of Orion, go to the easternmost – Alnitak – and Sigma is the first star south of it. In the telescope you will find a beautiful combination of four stars. The 3.8 magnitude white primary commands attention. With a designation of A/B, this super-massive and extremely bright pair are far too close (about 100 AU apart) to be split with a small scope. Looking 11″ to the southwest, you will discover the 10th magnitude white “C” star and you will see the 7.2 magnitude red “D” star 13″ to the east. Further away yet at a distance of 42″ to the east/northeast is the 6.5 magnitude blue “E” star.

Sharp-eyed observers will also note another multiple system in the same field of view to the northwest. This is Struve 761. As an “all white” system of similar magnitudes, you will see two residing east/west of each other and the third companion to the north. What we are looking at is a system that is about 1,500 light years away from us in the rich, star-forming region of Orion. Give that mouse a piece of cheese!

Saturday, December 25 – In keeping with the season, tonight’s astronomical object is a celebration of both starlight and asterism. Located 10 degrees east of Betelgeuse, the NGC 2264 will be a challenging object thanks to tonight’s near-full Moon, but the results will be quite worth it! Also known as “the Christmas Tree” cluster, this bright asterism of approximately 20 bright stars and over a 100 fainter ones is embroiled in a faint nebula that will be lost to bright skies, leaving only the delightful “Christmas Tree” shape adorned with stars. The very brightest of these stars, S Monoceros, is fifth magnitude and will show clearly in the finder scope and as a double at magnification. Steady skies will reveal that the “star” and the top of our “tree” is also a visual double and home to the beautiful “Cone Nebula”! Many of the stars will also appear to have companions, as well as tints of silver as gold. The visual effect of this splendid open cluster (as seen in this sketch by Jeff Barbour) is well worth the challenge it presents. Happy Holidays!

Sunday, December 26 – Did you get a new telescope? Then enjoy tonight’s full Moon! Although it is very bright, it is also the easiest of astronomical targets and will show many prominent features, bright rays and expansive plains of maria. If you are itching to explore, but unfamiliar with the sky, the Moon will offer to be your guide to one of the most exciting planets for the beginner – Saturn!

With the Moon in the constellation of Gemini tonight, you will see three “stars” gathered to the east. Point your telescope at the southern-most of this trio and enjoy the “Lord of the Rings”. Even small telescopes can appreciate the broad ring system, but there is also a treat tonight as well. Appearing to “follow” Saturn across the sky is its easily spotted moon, Titan!

I would like to thank all of you who have taken the time to write! Your observations of Comet Macholz have been wonderful, so please continue to observe it despite the Moon. I deeply appreciate all the kind words I have received. Do not be afraid to ask questions or share an observation. This column is all about you! Until next week? I wish you the very best of the season. Keep looking up and enjoying the wonders of our Universe! Light speed… ~Tammy Plotner

Posted on by Fraser Cain

Lighting Storms on Saturn

As NASA’s Cassini spacecraft approached Saturn last July, it found evidence that lightning on Saturn is roughly one million times stronger than lightning on Earth.

That’s just one of several Cassini findings that University of Iowa Space Physicist Don Gurnett will present in a paper to be published Thursday, Dec. 16, in Science Express, an online version of the journal Science, and in a talk to be delivered Friday, Dec. 17, at a meeting of the American Geophysical Union in San Francisco.

Other findings include:
–Cassini impacted dust particles as it traversed Saturn’s rings.
–Saturn’s radio rotation rate varies.

The comparison between Saturn’s enormously strong lightning and Earth’s lightning began several years ago as the Cassini spacecraft prepared for its journey to Saturn by swinging past the Earth to receive a gravitational boost. At that time, Cassini started detecting radio signals from Earth’s lightning as far out as 89,200 kilometers from the Earth’s surface. In contrast, as Cassini approached Saturn, it started detecting radio signals from lightning about 161 million kilometers from the planet. “This means that radio signals from Saturn’s lightning are on the order of one million times stronger than Earth’s lightning. That’s just astonishing to me!” says Gurnett, who notes that some radio signals have been linked to storm systems observed by the Cassini imaging instrument.

Earth’s lightning is commonly detected on AM radios, a technique similar to that used by scientists monitoring signals from Cassini.

Regarding Saturn’s rings, Gurnett says that the Cassini Radio and Plasma Wave Science (RPWS) instrument detected large numbers of dust impacts on the spacecraft. Gurnett and his science team found that as Cassini approached the inbound ring plane crossing, the impact rate began to increase dramatically some two minutes before the ring plane crossing, then reached a peak of more than 1,000 per second at almost exactly the time of the ring plane crossing, and finally decreased to pre-existing levels about two minutes later. Gurnett notes that the particles are probably quite small, only a few microns in diameter, otherwise they would have damaged the spacecraft.

Finally, variations in Saturn’s radio rotation rate came as a surprise. Based upon more than one year of Cassini measurements, the rate is 10 hours 45 minutes and 45 seconds, plus or minus 36 seconds. That’s about six minutes longer than the value recorded by the Voyager 1 and 2 flybys of Saturn in 1980-81. Scientists use the rotation rate of radio emissions from the giant gas planets such as Saturn and Jupiter to determine the rotation rate of the planets themselves because the planets have no solid surfaces and are covered by clouds that make direct visual measurements impossible.

Gurnett suggests that the change in the radio rotation rate is difficult to explain. “Saturn is unique in that its magnetic axis is almost exactly aligned with its rotational axis. That means there is no rotationally induced wobble in the magnetic field, so there must be some secondary effect controlling the radio emission. We hope to nail that down during the next four to eight years of the Cassini mission.”

One possible scenario was suggested nearly 20 years ago. Writing in the May 1985 issue of “Geophysical Research Letters,” Alex J. Dessler, a senior research scientist at the Lunar and Planetary Laboratory, University of Arizona, argued that the magnetic fields of gaseous giant planets, such as Saturn and Jupiter, are more like that of the sun than of the Earth. The sun’s magnetic field does not rotate as a solid body. Instead, its rotation period varies with latitude. Commenting earlier this year on the work of Gurnett and his team, Dessler said, “This finding is very significant because it demonstrates that the idea of a rigidly rotating magnetic field is wrong. Saturn’s magnetic field has more in common with the sun than the Earth. The measurement can be interpreted as showing that the part of Saturn’s magnetic field that controls the radio emissions has moved to a higher latitude during the last two decades.”

The radio sounds of Saturn’s rotation — resembling a heartbeat — and other sounds of space can be heard by visiting Gurnett’s Web site at: http://www-pw.physics.uiowa.edu/space-audio

Cassini, carrying 12 scientific instruments, on June 30, 2004, became the first spacecraft to orbit Saturn and begin a four-year study of the planet, its rings and its 31 known moons. The $1.4 billion spacecraft is part of the $3.3 billion Cassini-Huygens Mission that includes the Huygens probe, a six-instrument European Space Agency probe, scheduled to land on Titan, Saturn’s largest moon, in January 2005.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, Calif. manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter. For the latest images and information about the Cassini-Huygens mission, visit: http://www.nasa.gov/cassini.

Original Source: UI News Release