Posted on by Fraser Cain

More Radio Shows to Listen To

A mentioned a few months ago that I always tune a couple of science radio programs through the Internet: CBC’s Quirks and Quarks, and NPR’s Talk of the Nation Science Friday. Since then, I’ve turned up a few more shows to listen to on a regular basis. One is PlanetEarthRadio.com, which has dedicated streams just for space and astronomy. Another is the science programs on BBC Radio 4 which have been nicely archived for your listening pleasure. And Australia’s ABC has The Science Show.

My new favorite, however, is The Space Show, hosted by Dr. David Livingston. Each program is a 90-minute interview with a space scientist or advocate. I’m astonished and jealous at the caliber of guests Dr. Livingston has been able to get to interview. Give it a listen.

Do you have any other suggestions for radio shows to listen to? Send them in… I’m all ears.

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Binary Systems Could Create Most Nebulae

Image credit: Hubble

New research from the National Optical Astronomy Observatory may help to explain the formation and shape of many planetary nebulae. The culprit might just be binary star systems, where two stars orbit a common centre of gravity. Astronomers believe that planetary nebulae are caused when white dwarf stars slough off their outer layers, but they couldn’t explain how the nebulae could form jets of material or unusual lobes and prominences. A second star orbiting the dying white dwarf could whip up the outer layers into the strange shapes astronomers see.

Near the end of its lifetime, a star like the Sun ejects its outer layers into space, producing a hazy cloud of material called a planetary nebula. The complex shapes and dazzling colors of planetary nebulae make them some of the most popular objects in the night sky, for both amateur observing and scientific study.

New research suggests that many if not most of the stellar corpses at the centers of these wildly varied cosmic objects have companion stars, a surprising finding that will influence how astronomers explain their origins.

Astronomers used the Wisconsin-Indiana-Yale-NOAO 3.5-meter telescope at the National Science Foundation?s Kitt Peak National Observatory to take radial velocity measurements of 11 central stars of planetary nebulae (PNe), looking for the telltale, repeatable wobble that indicates the presence of a companion’s gravitational influence. This technique is also used to search for extrasolar planets around nearby stars. Ten of the 11 central stars of the PNe in the recent study showed clear evidence for radial velocity oscillations.

?If our current results are confirmed with further observations, we could be at the start of a revolution in the study of the origin of planetary nebulae,? says Howard Bond of the Space Telescope Science Institute in Baltimore, the principal investigator of the results presented today in Atlanta at the 203rd meeting of the American Astronomical Society. ?If these nebulae arise from binary stars, it implies a very different origin for these systems than what most astronomers had thought.?

It might be expected that nebulae ejected from spherical stars would be spherical, but many years of telescope observations show this not to be the case. In fact, most PNe are either elliptical or have pronounced lobes, often accompanied by jet-like structures.

There is general agreement that in order to eject gas with these observed morphologies, single stars would have to rotate rather rapidly or have reasonably strong magnetic fields, which themselves are the product of stellar rotation. However, the stars that most commonly eject PNe are large, bloated giants, indisposed to fast rotation.

?The most direct way to spin up these vast, fluffy stars is by the action of an orbiting companion. In extreme cases, as a red giant star gradually increases in size, it may actually swallow a companion star, which would then spiral down inside the giant and eventually eject its outer layers,? explains Orsola De Marco, an astronomer at the American Museum of Natural History (AMNH) in New York and the lead author of the publication reporting the first results of this project. ?Despite this, the mainstream astronomical view remains rooted in single star theories for the evolution of planetary nebulae, supported by the small percentage of planetary nebulae central stars that that were previously known to be binaries. However, our new research threatens to turn this viewpoint on its head.?

Astronomers currently believe that the majority of stars?those that begin with no more than eight times the mass of our Sun?end their lives by ejecting a planetary nebula and becoming a cosmic ember called a white dwarf. However, the new results from the WIYN telescope suggest that the story may be more complicated, in that an interaction with a companion star may be required to produce most planetary nebulae.

?We need more data to determine the exact periods of the binary central stars, since this is the only way to be sure of their binarity and eliminate other possible physical sources that could simulate the stellar wobble,? De Marco says. ?We are reasonably sure that these variations are due to binarity, but determination of their precise periods is the only way to be sure. We must also increase the size of our sample.?

Among the objects observed in this initial study are Abell 78, NGC 6891, NGC 6210, and IC 4593. The new radial velocity measurements were taken by the WIYN Hydra spectrographic instrument.

A previously released Hubble Space Telescope image of NGC 6210 is available at: http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/36/image/a

Co-authors of this work are Dianne Harmer of the National Optical Astronomy Observatory (NOAO) in Tucson, AZ, and Andrew Fleming of Michigan Technological University in Houghton, MI, an NSF Research Experiences for Undergraduates (REU) student at AMNH during the summer of 2003.

These results (Abstract 127.03 in the AAS meeting program) will be discussed in an oral session that begins at 10:00 a.m. on Thursday, January 8, in Regency VI. This research has been accepted for publication in the February 1, 2004, issue of Astrophysical Journal Letters.

Images of other planetary nebulae taken by Kitt Peak telescopes are available in the NOAO Image Gallery at:

http://www.noao.edu/image_gallery/planetary_nebulae.html
and
http://www.noao.edu/outreach/aop/observers/pn.html.

The Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5-meter telescope is located at Kitt Peak National Observatory, 55 miles southwest of Tucson, AZ. Kitt Peak National Observatory is part of the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation (NSF).

Original Source: NOAO News Release

Posted on by Fraser Cain

New Method for Finding Exploding White Dwarf Stars

Image credit: SDSS

Researchers at the University of Washington have developed a new method for studying unusual astronomical pairings: pre-cataclysmic variables – a white dwarf and red dwarf tightly orbiting one another. Before this new method, only 100 of these objects had been discovered, but this new method has turned up another 400 in data from the Sloan Digital Sky Survey. When the two stars get close enough, material from the red dwarf streams onto the white dwarf and deposits on the surface. This heats up the white dwarf and can cause it to explode as a supernova.

Until recently, astrophysicists studying exotic star systems pairing a white dwarf and a red dwarf in very close proximity didn’t have much to go on.

Just five years ago, scientists knew of fewer than 100 such systems, called pre-cataclysmic variables. But today a team of University of Washington astronomers said that, with data from the Sloan Digital Sky Survey (SDSS), the number has now grown to nearly 500.

That is significant because researchers are now able to study white dwarf and red dwarf stars at different stages of their life cycles, giving scientists the ability to compare them and develop an understanding of how the systems evolve and change over the course of billions of years, possibly becoming supernovas.

“We’ve never had the opportunity to study a variety of these systems in detail before now,” said Nicole Silvestri, a University of Washington astronomy researcher. Using this large sample from the SDSS, Silvestri and her colleagues believe they can begin to answer some of the long-standing questions in astronomy about pre-cataclysmic variables and their eventual end products, cataclysmic variable systems.

Silvestri is lead author of a poster presentation on the findings presented today (January 6, 2004) at the American Astronomical Society’s annual meeting in Atlanta. Co-authors of the project are Suzanne Hawley and Paula Szkody of the University of Washington’s Astronomy Department. The National Science Foundation supported the research.

Pre-cataclysmic variable systems pair a red dwarf star about one-tenth the size of our sun and a dense remnant of a star, called a white dwarf, in close orbit around each other. When the two stars are close enough, orbiting one another in less than four hours, the gravity of the denser white dwarf is able to pull material off of the less dense red dwarf. Material from the red dwarf forms a disk around the white dwarf that eventually accumulates on the surface of the white dwarf. (Variability refers to the changing amount of light coming from the stars as they orbit each other).

As the white dwarf gains mass, many small explosions, called cataclysmic events, occur on the surface of the white dwarf. If the white dwarf gravity gets to a critical point, it can collapse catastrophically. This heats up the white dwarf tremendously and may cause it to explode as a supernova.

Pre-cataclysmic variables found so far in the SDSS data have orbital periods of between four and 12 hours and are not close enough to have begun transferring material between the stars.

Silvestri said the evolution of a pre-cataclysmic variable to a cataclysmic variable takes billions of years and studying just one system as it evolves would be impossible. But with nearly 500 pre-cataclysmic variables to study, “A dataset of this size will allow us to take snapshots in time of the evolution of the system,” she said. “This will allow the researchers to study how properties of each star change as the pair draw closer to each other, something that until now, has never been investigated.”

Silvestri and her colleagues are still at a loss to explain one oddity in the research. Thousands of isolated white dwarfs have been observed and hundreds of them have been found to be magnetic. And many white dwarfs in cataclysmic variables are magnetic. But not one of the white dwarfs observed in the pre-cataclysmic variable systems is magnetic.

“This makes the origin of magnetic cataclysmic variables (known as polars), which do contain magnetic white dwarfs, exceedingly mysterious,” added SDSS researcher Suzanne Hawley of the University of Washington.

“That’s a question we’re still trying to find an answer to,” Silvestri said. “How do you get a magnetic white dwarf in a cataclysmic variable if it doesn’t originate in one of these pairs that is evolving toward being a cataclysmic variable?” The University of Washington team, James Liebert of the University of Arizona and others are preparing a paper on that finding for the Astronomical Journal.

Original Source: SDSS News Release

Posted on by Fraser Cain

Rosetta Prepares for Mission to Comet 67P/Churyumov-Gerasimenko

Image credit: ESA

The European Space Agency’s comet chasing spacecraft, Rosetta, is being prepared for its trip into space? again. After a series of technical problems and missed opportunities, the spacecraft is now being targeted to chase down Comet 67P/Churyumov-Gerasimenko; it will reach the comet and go into orbit in August 2014. The spacecraft will map the surface of the comet in great detail and then actually land on the surface and provide high resolution images from the “ground”.

ESA?s comet chaser will soon be heading towards a new target, known as 67P/Churyumov-Gerasimenko, but the mission team is confident that a rich scientific bonanza awaits when Rosetta arrives at its destination in the summer of 2014.

One year ago, scientists around the world were eagerly awaiting the start of Rosetta?s historic voyage to orbit and land on a small comet called 46P/Wirtanen. Then, following a mishap with an Ariane 5 launch vehicle, the spacecraft?s odyssey was put on hold and mission planners began to search for other comets that would be within Rosetta?s range.

Following careful analysis of the available objects and associated launch constraints for each option, the ESA Science Programme Committee eventually accepted the recommendation to send Rosetta to another periodic intruder into the inner Solar System, comet Churyumov-Gerasimenko.

Under the revised flight plan, the hardy spacecraft will now make one flyby of Mars and three flybys of Earth en route to the comet. This circuitous trek will enable Rosetta to make two excursions into the main asteroid belt before its rendezvous with the fast-moving cosmic iceberg.

At present, the amount of science that can be conducted during the 10-year trek to comet Churyumov-Gerasimenko remains uncertain. Some scientific observations of the Red Planet will be possible during the Mars encounter, and there is likely to be at least one opportunity to study a main belt asteroid at close quarters. A number of possible candidates have already been identified, but the final selection will be made after launch, once the mission team has determined how much surplus fuel is available on the spacecraft.

However, the most exciting phase of Rosetta?s 11-year odyssey will come when it brakes into orbit around Churyumov-Gerasimenko in August 2014. From an altitude of just a few kilometres, its cameras will be able to map the entire pockmarked surface of the icy nucleus at high resolution and search for suitable landing sites.

Once the surface of the comet?s nucleus has been surveyed in unprecedented detail and a safe landing site has been selected, the Rosetta lander will separate from the orbiter and slowly descend to the pristine surface. If all goes according to plan, the lander will anchor itself to the icy crust and begin a detailed survey of its surroundings.

Over a period of several weeks, a treasure trove of data from the nine instruments on the lander will be sent back to Earth via the Rosetta orbiter. During its historic foray, the lander will return close-up pictures of the comet?s nucleus, drill into the dark organic crust, and sample the primordial ices and gases. Even the internal structure of the dirty snowball will be probed as radio signals from the orbiter pass through the nucleus to the lander and back again. For the scientists, this ?ground truth? data will provide invaluable validation of the remote observations sent back by the orbiter as its skims over the undulating surface of the small ice world.

Meanwhile, the orbiter will continue to monitor the dramatic changes in the nucleus that take place during its headlong plunge towards the inner Solar System. Over a period of about 18 months, the 11 experiments on the Rosetta orbiter will examine every aspect of the comet?s behaviour during its headlong plunge towards the inner Solar System.

Since Churyumov-Gerasimenko typically becomes much more active than Wirtanen as it approaches the Sun, scientists expect to observe at close quarters for the first time the remarkable transformation of a comet from a tranquil iceberg into a world of turmoil. In particular, as its ices sublimate, bright jets will appear, ejecting gas and dust into space to create a coma and a distinctive tail that stretches vast distances in the anti-sunward direction.

Despite its generally more active nature, the dust environment close to the comet is probably little more hazardous for the spacecraft than it would be in the vicinity of comet Wirtanen. Churyumov-Gerasimenko?s larger perihelion distance means that its nucleus is heated less strongly by the Sun, so limiting the output of gas-laden dust that could threaten the orbiter.

According to ESA?s Rosetta project scientist, Gerhard Schwehm, it should be an exciting time for everyone concerned.

?Ground observations have shown that the comet becomes active at around 3 AU (about 450 million km from the Sun),? he said. ?We see a lot of jets and surface activity with considerable structure in the coma.?

?Since Churyumov-Gerasimenko has only made a few passes through the inner Solar System, it is still a fairly fresh, active comet, which produces a lot of gas and dust. By flying alongside it for more than a year, we shall be able to observe the dramatic transformation that takes place as it is warmed by the Sun. It will also be intriguing to see how the activity dies down after it passes perihelion and begins the outward leg of its orbit.?

?Working in unison, the lander and the orbiter will revolutionise our understanding of comets,? said Schwehm. ?They will lead to amazing discoveries about the most primitive building blocks of the Solar System.?

In particular, the enormous flood of data returned during Rosetta?s remarkable voyage will provide new insights into such fundamental mysteries as the formation of Earth?s oceans and the origin of life.

It may even help the human race to survive in the long term. By transforming our understanding of the Solar System?s icy wanderers, Rosetta will give us vital insights about how to respond should we find a comet on a collision course with the Earth.

Rosetta?s unique odyssey of exploration will terminate in December 2015, six months after the comet passes perihelion and begins its retreat to the more frigid regions of Jupiter?s realm. After a dramatic saga lasting almost 12 years, the curtain will fall on the most ambitious scientific mission ever launched by Europe.

But, for the scientists, the work will only just be beginning.

Original Source: ESA News Release

Posted on by Fraser Cain

Sea Launches Sends Telstar 14/Estrela do Sul 1 Into Orbit

Image credit: Boeing

Sea Launch successfully launched the Telstar 14/ Estrela do Sul 1 communications satellite into orbit over the weekend. The Zenit 3SL rocket lifted off from the floating Sea Launch platform on January 10 at 0413 UTC (11:13 pm EST January 11), and the dual satellite separated from the upper stage shortly after that. The satellite will provide television, data, and communication services to the Americas and the North Atlantic Ocean.

Sea Launch Company successfully deployed Loral?s Telstar 14/Estrela do Sul 1 communications satellite into orbit tonight. All systems aboard the Space Systems/Loral 1300-series spacecraft are reported in excellent condition.

The Sea Launch Zenit-3SL rocket lifted off at 8:13 pm PDT (4:13 GMT, January 11) from the Odyssey Launch Platform, positioned at 154 degrees West Longitude, on the Equator. All systems performed nominally throughout the flight. The Block DM-SL upper stage inserted the 4,694 kg (10,350 lb) spacecraft into a high perigee geosynchronous transfer orbit right on target. As planned, a ground station in Western Australia received the spacecraft?s first signal, shortly after spacecraft separation. The spacecraft?s final orbital position will be 63 degrees West Longitude.

Jim Maser, president and general manager of Sea Launch, said after completion of the mission, ?This is the first launch of the year for the industry and it?s a great way to start the year for Sea Launch, for Loral Space & Communications and for the industry. This is our second mission for our Loral customer and the first of three Loral missions we plan to complete early this year.?

The Telstar 14/Estrela do Sul 1 satellite was built by Space Systems/Loral and will be operated by Loral Skynet do Brasil. The spacecraft carries 41 high-powered Ku-band transponders with five unique and interconnecting coverage beams. The satellite will serve growing markets such as broadcast video and cable programming, Internet backbone connectivity, VSAT data and other telecommunications services. More than fifty percent of the satellite?s power will be focused on Brazil, providing dedicated Ku-band solutions for the Brazilian marketplace. The satellite?s other beams will cover the Americas and the North Atlantic Ocean, where Connexion by Boeing? will use the satellite to support its Internet-to-aircraft service.

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

Original Source: Boeing News Release

Posted on by Fraser Cain

Panoramic View of Mars

Image credit: NASA/JPL

Mission controllers have released the first panoramic 360-degree view of the Martian landscape taken by the Spirit rover. The colour panorama is a mosaic stitched together from 225 separate images taken by Spirit’s panoramic camera. Not only is it pretty, but it’s a handy tool for the team’s scientists to get an understanding of all the terrain around the rover so they can start prioritizing their targets. One of their greatest interests is how the ground near the rover folded up like a carpet when the lander retracted the airbag. This was totally unexpected, and still a bit of a mystery. Spirit is expected to roll off the lander within two days.

The first 360-degree color view from NASA’s Spirit Mars Exploration Rover presents a range of tempting targets from nearby rocks to hills on the horizon.

“The whole panorama is there before us,” said rover science- team member Dr. Michael Malin of Malin Space Science Systems, San Diego. “It’s a great opening to the next stage of our mission.”

Spirit’s flight team at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., continues making progress toward getting the rover off its lander platform, but expected no sooner than early Thursday morning. “We’re about to kick the baby bird out of its nest,” said JPL’s Kevin Burke, lead mechanical engineer for the rover’s egress off the lander.

The color panorama is a mosaic stitched from 225 frames taken by Spirit’s panoramic camera. It spans 75 frames across, three frames tall, with color information from shots through three different filters. The images were calibrated at Cornell University, Ithaca, N.Y., home institution for Dr. Jim Bell, panoramic camera team leader.

Malin said, “Seeing the panorama totally assembled instead of in individual pieces gives a much greater appreciation for the position of things and helps in developing a sense of direction. I find it easier to visualize where I am on Mars when I can look at different directions in one view. For a field geologist, it’s exactly the kind of thing you want to look at to understand where you are.”

Another new image product from Spirit shows a patch of intriguing soil near the lander in greater detail than an earlier view of the same area. Scientists have dubbed the patch “Magic Carpet” for how some soil behaved when scraped by a retracting airbag.

“It has been detached and folded like a piece of carpet sliding across the floor,” said science-team member Dr. John Grotzinger of Massachusetts Institute of Technology, Cambridge.

Spirit’s next step in preparing to drive onto the surface of Mars is to sever its final connection with the lander platform by firing a cable cutter, which Burke described as “an explosive guillotine.” The planned sequence after that is a turn in place of 115 degrees clockwise, completed in three steps over the next two days. If no obstacles are seen from images taken partway through that turn, drive-off is planned toward the northwestern compass point of 286 degrees.

Spirit landed on Mars Jan. 3 after a seven-month journey. Its task is to spend the next three months exploring rocks and soil for clues about whether the past environment in Gusev Crater was ever watery and suitable to sustain life. Spirit’s twin Mars Exploration Rover, Opportunity, will reach Mars Jan. 24 PST (Jan. 25 Univeral Time and EST) to begin a similar examination of a site on a broad plain called Meridiani Planum, on the opposite side of the planet from Gusev Crater.

NASA JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington. For information about NASA and the Mars mission on the Internet, visit: http://www.nasa.gov. Additional information about the project is available on the Internet at: http://marsrovers.jpl.nasa.gov. Mission information is also available from Cornell University, at: http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Improvements to Universe Today

The constant feedback I’ve had from readers is: more pictures. Okay, you want pictures? I’ll give you pictures. Here, have all the pictures you can handle. I’ve added a new type of story called “Photo Gallery”, which will showcase a few big pictures, plus have a link to a wallpaper version. I’ve also increased the size of pictures in the stories about 4X. Check them out, and then let me know what you else you might want to make this better.

I’ve also added a list of recent conversations in the forum beside every story in the site. Hopefully this will remind you that we’ve got a thriving forum for space enthusiasts. Come and join us!

Take care,

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Astronauts Find the Source of the Leak

The astronauts on board the International Space Station have finally located the tiny air leak that was puzzling them for several weeks; not to mention steadily dropping the air pressure on the station. The leak appears to be on a cable which equalizes pressure on the main window in the US-built Destiny laboratory module. Fortunately, the astronauts have the equipment they need to temporarily repair it, and a replacement part can be shipped up on the next Progress cargo flight.

Posted on by Fraser Cain

Spirit Will Roll Off Secondary Ramp

Image credit: NASA/JPL

After several attempts to collapse the airbag which is blocking Spirit’s exit from the lander, controllers have given up that plan. Instead, they’ve decided to have the rover exit from one of the platform’s alternate ramps. In order to take this northeastern route, the rover will have to back up and then perform a three-point turn in the tight space. Controllers will also fire a pyro device which will sever an umbilical cord connecting the rover to the lander. If everything goes as planned, Spirit will roll off the lander on the evening of January 14.

NASA’s Spirit rover now has its arm and all six of its wheels free, and only a single cable must be cut before it can turn and roll off its lander onto the soil of Mars. As that milestone is completed, scientists are taking opportunities to take extra pictures and other data.

During the past 24 hours — the rover’s 8th martian day on the planet, or “sol 8” — pyro devices were fired slicing cables to free the rover’s middle wheels and releasing pins that held in place its instrumented arm. The arm was then locked onto a hook where it will be stowed when the rover is driving.

Because one airbag remains adjacent to the lander’s forward ramp, the rover will turn about 120 degrees to its right and exit the lander from the side facing west-northwest on the planet — also the direction of an intriguing depression that scientists have dubbed Sleepy Hollow.

Current plans call for the rover to complete that turn in three steps, said Arthur Amador, one of the mission managers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. As currently envisioned, during the coming martian day engineers will complete ground tests and execute dress rehearsals of the drive-off, or “egress.”

On sol 10 — the night of Monday-Tuesday, Jan. 12-13, California time — engineers expect to sever the umbilical cord that connects the rover to its lander by firing a pyro device, the last of 126 pyro firings since Spirit separated from its cruise stage shortly before landing on Jan. 4 (Jan. 3 in U. S. time zones). Also on that day, the rover will execute the first of three parts of its turn when it moves clockwise (as viewed from above) about 45 degrees.

After taking and analyzing pictures to verify the first part of the turn, engineers anticipate completing it on sol 11 (night of Tuesday-Wednesday, Jan. 13-14). First, the rover will turn an additional 50 degrees and stop to take pictures. Then, if all is well, it will turn a final 20 to 25 degrees to position it precisely in front of one of its three exit ramps.

If no issues crop up as those steps are completed, the rover could drive off onto the martian soil no earlier than sol 12 (night of Wednesday-Thursday, Jan. 14-15). “But we adjust our schedule every day, based on flight events, so this remains an estimate,” said Amador.

The rover’s status overall is “pretty darn perfect,” said Amador. He described the communication link from Mars to Earth as excellent, allowing the team to receive 170 megabits of data during the past day. All science data stored on the rover has been sent to Earth. The rover is generating 900 watt-hours of power per day and using 750 watt-hours, and its thermal condition is good, he added.

While engineers are completing and testing commands to execute the rover’s turn and egress, the science team is enjoying an “unexpected dividend” of time to collect data, said Dr. John Callas, Mars Exploration Rover science manager at JPL.

Until now, all science observations have been planned far in advance, but the unfolding schedule of rover activities gave the team the opportunity to do their first on-the-fly planning for observations driven by previous results, Callas explained. In doing so they segued to a working style that they will practice on a day to day basis as the rover rolls across the surface of its landing site in Gusev Crater, named the Columbia Memorial Station.

In the next 24 hours, the team will collect 270 megabits of science data, considerably more than on any previous martian day. This will include a high-quality, 14-color mosaic taken by the panoramic camera of a third of the horizon toward Sleepy Hollow, the direction in which the rover will leave its lander.

In addition, they plan to complete two remaining “octants” (each a pie slice showing an eighth of the horizon) with the rover’s miniature thermal emission spectrometer. These areas will also be rephotographed with the rover’s panoramic camera in order to allow the camera and spectrometer data to be co-registered. Plans also call for the spectrometer to “stare” at three selected sites to collect very low-noise data, as well as calibration of another science instrument, the alpha particle X-ray spectrometer.

Spirit’s twin Mars Exploration Rover, Opportunity, will reach Mars on Jan. 25 (Universal Time and EST; Jan. 24 PST). The rovers’ main task is to spend three months exploring for clues in rocks and soil about whether the landing sites may have had abundant water for long enough in the past for life to appear. Pictures and detailed information from the mission is available at the project’s Web site: http://marsrovers.jpl.nasa.gov.

JPL, a division of the California Institute of Technology, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Eye Tower Makes Hurricanes Stronger

Image credit: NASA

NASA scientists have discovered that a “hot tower” of cloud rising above the eye of a hurricane can increase its intensity. The scientists used data gathered by the TRMM satellite; a joint project by NASA and the Japanese Aerospace Exploration Agency. After compiling statistics from several storms, they found that when a hot tower forms up to 15 kilometres above the eye, the hurricane will become much more intense within six hours. This research could help improve forecasts of which hurricanes have the potential to cause the most damage.

They are called hurricanes in the Atlantic, typhoons in the West Pacific, and tropical cyclones worldwide; but wherever these storms roam, the forces that determine their severity now are a little less mysterious. NASA scientists, using data from the Tropical Rainfall Measuring Mission (TRMM) satellite, have found “hot tower” clouds are associated with tropical cyclone intensification.

Owen Kelley and John Stout of NASA’s Goddard Space Flight Center, Greenbelt, Md., and George Mason University will present their findings at the American Meteorological Society annual meeting in Seattle on Monday, January 12.

Kelley and Stout define a “hot tower” as a rain cloud that reaches at least to the top of the troposphere, the lowest layer of the atmosphere. It extends approximately nine miles (14.5 km) high in the tropics. These towers are called “hot” because they rise to such altitude due to the large amount of latent heat. Water vapor releases this latent heat as it condenses into liquid.

A particularly tall hot tower rose above Hurricane Bonnie in August 1998, as the storm intensified a few days before striking North Carolina. Bonnie caused more than $1 billion damage and three deaths, according to the National Oceanic and Atmospheric Administration National Hurricane Center.

Kelley said, “The motivation for this new research is that it is not enough to predict the birth of a tropical cyclone. We also want to improve our ability to predict the intensity of the storm and the damage it would cause if it struck the coast.” The pioneering work of Joanne Simpson, Jeffrey Halverson and others has already shown hot towers increase the chance a new tropical cyclone will form. Future work may use this association to improve forecasts of a cyclone’s destructive potential.

To achieve their goal, Kelley and Stout needed to compile a special kind of global statistics on the occurrence of hot towers inside tropical cyclones. The only possible data source was TRMM satellite, a joint effort of NASA and the Japan Aerospace Exploration Agency. “Many satellites can see the top of a hot tower, but what’s special about this satellite’s Precipitation Radar is that it gives you ‘X-ray vision’ so you can see inside a hot tower,” Kelley said. To compile global statistics, the radar needs to be orbiting the Earth.

After compiling the statistics, Kelley and Stout found a tropical cyclone with a hot tower in its eyewall was twice as likely to intensify within the next six hours than a cyclone that lacked a tower. The “eyewall” is the ring of clouds around a cyclone’s central eye. Kelley and Stout considered many alternative definitions for hot towers before concluding the nine-mile height threshold was statistically significant.

Funding for the research was provided by NASA’s Earth Science Enterprise. The Enterprise strives to advance Earth System Science and to improve the prediction of climate, weather and natural hazards from the unique vantage point of space.

Original Source: NASA News Release