This transcript is provided as a service; there may be some variation between it and the program as broadcast.

MUSIC: Our World theme

Straight ahead on "Our World" ... The shuttle returns and a Mars mission takes off ... Plant scientists decode the genetic structure of rice ... and fishing fleets discover a loss of diversity in the world's oceans.
MYERS: "For the same number of hooks you set out, you now get one-half as many species as you did fifty years ago."

Vanishing fish, a visit to a very special place -- America's tallgrass prairie -- and more... I'm Art Chimes.  Welcome to VOA's science and technology magazine, "Our World."


The space shuttle Discovery glided to a safe landing in California Tuesday, after delays caused by weather at the main landing site in Florida.

COLLINS: Houston, Discovery. Wheel stop.
CAPCOM: Roger wheel stop, Discovery. And congratulations on a truly spectacular test flight.

This was the first shuttle flight since 2003, when another shuttle, Columbia, broke up as it re-entered Earth's atmosphere. All seven astronauts were killed, and NASA has spent the past two and a half years on safety upgrades to the shuttle.

In addition to being the first shuttle flight since then, Discovery's mission was marked by the first in-flight repair to the outside of the shuttle vehicle by space-walking astronaut Steve Robinson. He told reporters that the ability to fix the spacecraft is key to the next stage of human spaceflight, when the destination is the moon or Mars, not just low earth orbit.

ROBINSON:  "Things are going to fail, and they need to be repaired. We're pretty good at repairing things on the inside. We've been fairly successful at repairing sort of packaged things on the outside [such as] replacing a box. What we haven't done much of is repairing some of the things that aren't really designed to be repaired. We made the first baby step of that, I think, on this mission."

In 2003, the shuttle Columbia's problem began when a piece of insulating foam broke off the large external fuel tank during launch.  The debris damaged the leading edge of a wing. That fatal puncture allowed hot gases to penetrate the shuttle's heat shield during its fiery re-entry into the earth's atmosphere. NASA thought it had fixed the problem, but there were foam debris problems on this mission, too, though none that damaged the spacecraft.

NASA officials said Thursday there is no obvious cause of the foam problem, and thus no easy fix. NASA has suspended shuttle flights until the issue is resolved, and a mission planned for September now seems increasingly unlikely.

Nevertheless, space agency administrator Michael Griffin downplayed the frustrating foam issue and focused on the just-completed Discovery flight.

GRIFFIN:  "I think the crew performed beyond fantastically well. It's going to be really hard to top this mission."

The space agency plans to fly the shuttle for another five years to finish building the space station before retiring the aging spacecraft and shifting the focus to sending humans back to the Moon and to Mars.

Some critics say that the shuttle is too dangerous to continue flying.  After more than two decades of shuttle flights, Historian Roger Launius of the National Air and Space Museum says the program is leaving a mixed legacy.

LAUNIUS:  "They failed to achieve their fundamental goal, which was to make routine space access available and affordable. And the reality is, if you want to measure it in someway, they probably got 75-80 percent [of] where they wanted to go, in terms of their goal. That's not a failure. That's a learning process, and that's exactly, I think, what happened."

If the space agency gets mixed marks on its shuttle program, it won near-universal praise for its last unmanned mission to Mars. Twin rovers Spirit and Opportunity have been crawling around the Martian surface since January 2004, and they continue to send back intriguing data about the geology of the red planet.

But the rovers are confined to only a tiny patch of Martian real estate. The two of them combined have logged just 10 kilometers rolling over Mars' rugged terrain.

Another Mars mission roared into space Friday.  Instead of landing on the planet's surface, the Mars Reconnaissance Orbiter will go into orbit and, as VOA's David McAlary reports, the craft is expected to send back unprecedented information about our closest planetary neighbor.

McALARY:  Since 1997, the U.S. space agency, NASA, has been dispatching orbiters and companion landers to Mars about every two years, to seek a better geological understanding of Earth's nearest planetary neighbor. It especially wants to learn if conditions ever existed that could have supported life. The next in the series is the huge Mars Reconnaissance Orbiter, two stories tall and nearly 15 meters wide.

The head of NASA's Mars exploration program, Douglas McCuistion says the effort now moves into a more intensive phase of investigation.

McQUISTION:  "So this is a big mission for us. It's big in the strategic role in the Mars exploration program, it's the biggest orbiter sent to Mars in the past 30 years, carrying the most powerful suite of remote sensing instruments ever deployed to another planet."

McALARY:  NASA says the Mars Reconnaissance Orbiter will have better capabilities for understanding the red planet's surface, subsurface, and atmosphere than the American and European satellites now orbiting, the two U.S. robotic rovers on the ground, or any previous mission.

ZUREK:  "It's a weather satellite, it's a geological surveyor, it's a pathfinder for future missions."

McALARY:  This is NASA project scientist Richard Zurek. He says the new orbiter, known by its English initials MRO, carries six instruments. Some are designed to seek clues to the water most planetary scientists believe once flowed on Mars and is a key to life. They can identify water-related minerals and penetrate the ground about one kilometer to seek layers of rock, ice, and water if it is present.

ZUREK:  "MRO follows the 'Follow the Water' program by combining global monitoring of the atmosphere and surface, by taking regional surveys of interesting areas, and then zooming in with very high resolution observations of the surface of the planet. Together, these data sets provide a new window into Mars' history and they will provide the best sites for future landers to go and explore with some confidence that they are safe sites."

McALARY:  The Mars Reconnaissance Orbiter has five times better resolution over more area than its predecessor satellites. It can see things as small as a dinner plate thanks to super-sharp cameras and a planned altitude 20 percent lower than previous spacecraft -- about 300 kilometers.

ZUREK:  "Every time we have increased our ability to resolve detail on the planet, we see new things, and we expect new surprises."

McALARY:  With so much power to collect information, NASA had to give the new spacecraft the means to send huge amounts of it back to Earth, quickly. So the orbiter carries the largest antenna ever sent to Mars, three meters in diameter, and a transmitter powered by large solar panels. The space agency's manager for the project, James Graf, says the data flow will be 10 times per minute higher than previous Mars orbiters.

GRAF:  "These other missions have been producing fantastic data, but they have been bringing the data back through, essentially, a straw. What we are going to do is open the spigot and bring it back through a fire hose. That's crucial if you want to understand Mars. You want to increase the coverage and the resolution of your measurements, so you need that greater data."

McALARY:  The Mars Reconnaissance Orbiter is to arrive at its destination in March of next year and begin returning data by the end of the year. First, though, it must gradually adjust its extremely oval orbit to a circular one using atmospheric friction. Its primary data gathering phase is scheduled to last two years, but NASA says it is capable of going for up to a decade. David McAlary, VOA News, Washington.

Rice is perhaps the world's most important food. Now, scientists have finished decoding the genetic structure of rice, and as we hear from VOA's Jessica Berman, the work could lead to a significant increase in the output of rice and other grains to meet the world's growing food needs. 

BERMAN:  Experts say more than half of the world's population eats rice as part of the daily diet.  They project that over the next two decades, the demand for rice will grow by 30 percent as the global population increases.  But with present conditions, there won't be enough rice to go around.

So plant geneticists have been working to identify the molecular building blocks of rice that could potentially increase yields by making the grain resistant to pests, diseases and harsh weather conditions.

In a study published in the August 11 issue of the journal Nature, researchers from 10 countries, led by Japan's International Rice Genome Sequencing Project, report pinpointing the locations of more than 37,500 rice genes along the plant's 12 thread-like chromosomes. 

The genetic material is tightly packed inside the nucleus of each cell and is responsible for a wide variety of plant traits.

Researcher Robin Buell of the Institute for Genomic Research in Rockville, Maryland, says different strains of rice have different characteristics that make them vulnerable to various growing conditions. 

For example, she says some strains are more tolerant of stressful conditions but yield less than strains that are susceptible to diseases or unfavorable soil conditions.

BUELL:  "So, what you want to do is something that is well known in the breeding community called hyper-vigor where you bring the best traits from two very different parents and bring them together and try to make the optimal variety. So, having the genome sequence will accelerate peoples' efforts to identify the genes that are important for these traits and  bring them together in a genetic background that's most well-adapted to the environmental conditions."

BERMAN:  Researchers began sequencing the rice genome in 1998.

Now that it's complete, study co-author of Richard McCombie of Cold Spring Harbor Laboratory in New York says the public will be able to gain free access to all or parts of the genetic information.

MCCOMBIE:  "Having the whole thing also makes it possible that people can look at just small parts of it that are of interest to them.  So for instance if scientists and breeders in a given country have mapped a trait that is very important to the agriculture in their country, they can look in that region now of the genome and look at that small part of the sequence and see the genes that are there."

BERMAN:  Researchers say the finished rice sequence shows that it shares many of the same genes with other cereal grains, including corn, wheat, and barley, holding out the potential for improvement of those crops as well. Jessica Berman, VOA News, Washington.

If you use a computer, or follow news about computers, you probably know that computer security is a big issue. Theft of credit card numbers from bank databases and computer viruses that shut down entire networks are just two of the threats. As computers have become democratized in recent years, more and more computing power is in the hands of people who just want to send an e-mail, surf the web or write a school report. Unfortunately, though, the sad truth is that today, if you use a computer, you really need to know something about computer security. And that's where our website of the week comes in.

HERZOG:  "Hacker Highschool -- believe it or not, from the name -- is actually a series of lessons in critical thinking. One of the problems we found was that there was no modern or exciting way to teach critical thinking to kids. So we tried to find a way to get kids to understand more about security, to make security decisions, based on logic."

Pete Herzog is Managing Director at ISECOM, a computer security institute that has created a series of online lessons in computer security at  Much to the dismay of many computer specialists, most people think a "hacker" is someone who breaks into computer systems and wreaks havoc. Computer geeks, however, would go with the dictionary definition: "an expert at programming and solving problems with a computer." The Hacker Highschool program teaches awareness about computer security issues, and how to respond to them.

HERZOG:  "Mostly the focus is on how to identify threats and, well, also understand what a threat really is. There's a lot of things that seem innocent, for example, spam. Spam is something that can be quite dangerous, once it gets on your system. Especially if it's coupled with malware."

Malware is malicious software, including viruses, worms, trojan horses, and the like.

The Hacker Highschool curriculum is designed to be taught in the classroom, but the lessons on their website can be used outside the classroom, too.

HERZOG:  "Anybody can download them. There's a lot of people, actually, who do download them and do it at home. As a matter of fact, home-schooling is a big one. We have a lot of home-schoolers who use it. We have a special network set up so they can actually study from home."

The Hacker Highschool curriculum is in use now in Spain, where we reached Pete Herzog, as well as other locations in Europe, in Asia and in the Americas. Check it out at HackerHighschool -- all one word -- HackerHighschool-dot-org, or get the link from our site,

MUSIC: "High School Cadets" by John Philip Sousa, performed by Paul Lavalle

It's VOA's science and technology magazine, Our World. I'm Art Chimes in Washjington.

SKIRBLE:  The open ocean is the world's largest ecosystem.  This deep blue water far from land is where the most commercially popular fish ? tuna, marlin and swordfish ? are caught.  Dalhousie University biologist Ransom Myers mapped the hotspots where these large marine predators congregate and writes about them in the journal Science.

MYERS:  "Off of Florida is one.   South of Indonesia is another.   Actually the whole Indian Ocean is incredibly diverse.  And, south of Hawaii is another one of these diversity hotspots."

SKIRBLE:  But these hotspots are shrinking.  For example, the ocean off Northwestern Australia ? once home to the most diverse collection of tuna and billfish species i? s now indistinguishable from the rest of the ocean.

MYERS:  "For the same number of hooks you set out, you now get one-half as many species as you did fifty years ago."

SKIRBLE:  The study analyzed data from Japanese longlines, the most widespread fishing gear in the open ocean.  Researchers also examined scientific observations from United States and Australian government agencies.  The study is the first to examine the impact of climate change and industrial fishing on a global scale.  Co-author Ransom Myers says the data indicate a dramatic shift in fish population and the decline of large predator species. He says those changes have a ripple effect. 

MYERS:  "You knock out the big predators and generally, unusual and unforeseen and bad things happen to humans.  So, you knock out hammerhead sharks and you will get an increase in stingrays that eat lobster and you may care about eating spiny lobster.  On coral reefs if you take out the coral reef fish and the reefs will overgrow with algae and die and so protecting these large fish is essential for protecting the ecosystem."

SKIRBLE:  Ransom Myers says over-fishing is the major force behind the decline in bio-diversity.  He says the consequences ? while not completely understood ? could be huge.

MYERS:  "Species diversity is really, really important because it is that diversity among species and within species that we need to allow fishing to take place, to allow the variability to allow the ecosystems to respond to change.  By over-fishing we are removing that variability.  Thus the ecosystems will not be able to respond as they need to as climate changes and fishing occur."

SKIRBLE:  But Ransom Myers says the trend can be reversed, says the study can help identify areas for greater protection.

MYERS:  "It points to a need for international agreement to have high seas closed areas, areas of the open ocean where there is no over fishing and that are protected from fishing to allow these species to increase and maintain themselves so they can be optimally harvested and give us maximum protein for the food and maximum diversity and enjoyment for sports fishing, and enjoyment just to know that the world is a better place to have these magnificent fish in it."

SKIRBLE:  The study in the journal Science is part of the Census of Marine Life, a $1 billion, 10-year international effort to identify the species in the world's oceans.  I'm Rosanne Skirble.

The North American Prairie, a vast grassland that once covered much of the central United States, was one of the most complex ecosystems in the world. Today, most of that prairie has been fenced in or converted to farmland, and the millions of bison, antelope and elk that once grazed on it are mostly gone. However, one can still find a pristine 40,000-hectare piece of that natural wonder in the Flint Hills of eastern Kansas. VOA's Adam Phillips sent us this report.

PHILLIPS:  Americans who believe that the state of Kansas, in the central United States, is flat and featureless may have never seen the Tallgrass Prairie National Preserve. In the summertime, the sight of its gently undulating rises of shoulder-high grasses  mostly Big Bluestem, Little Bluestem, Indiangrass and Switchgrass -- take Ranger Ron Clarks breath away.  

CLARK:   I see Wavy-leaf thistle blooming lavender, yellow coneflower, prairie clover, some white prairie clover. Of course what I am looking at mostly are forty kinds of grasses that make up 80 percent of what you see that is green, and yet only comprise, well, less than ten percent of the plant community. Believe it or not, eighty percent of the grass is underground. That's what enables them to sustain periods of drought periods, fire and grazing.

PHILLIPS:  The rhythms of fire and grazing are key to understanding the tallgrass prairie, where, for untold millennia, antelope, bison and elk grazed on their migrations, trimming back extra growth while ingesting the rich nutrients they needed to stay strong, mate and move on. And every five to seven years, natural fires caused by lightning would burn away the dead grass and make way for new shoots. Today, ranchers graze cattle on the prairie to fatten them up, and Ranger Clark says that the ancient fire cycle is renewed every spring, when those ranchers set a controlled prairie burn that nature once set at random.   

CLARK:  "And after the burn you just see nothing but rock out here  you wonder how anything can grow.  But the grasses rooting down as much as ten or twelve feet come back quickly under good rain and warm temperatures, and, within about two weeks it looks like a sculptured golf course. Within a month you can turn steers out there and they will put on several pounds a day on this grass. Its incredible. Most people have no idea of the richness of this landscape.

PHILLIPS:  The richness of the soil is largely due to the calcium and other minerals left here by the marine life that lived and died here millions of years ago when this part of North America was covered by a vast inland sea. Ranger James Kemo specializes in prairie geology. 

KEMO:  "And when it was warm it would be full of crustaceans, bivalves, coral and sponges ? animals that absorbed the calcium from the seawater and excreted it to make their skeletons or their shells. And as they died, that mass would drop to the bottom of the sea And it makes for a very good soil for these grasses. 

PHILLIPS:  Today, grasshoppers are the Tallgrass Prairies primary grazer, and Ranger Clark says that coyotes eat the grasshoppers.

CLARK:  Two thirds of a coyotes diet out here in the middle of summer are made of grasshoppers. The coyotes then of course in the winter will feed on rabbits and prairie pocket gophers that may be out and so the cycle goes on.

PHILLIPS:  Ron Clark is a ranger, not a scientist. Still, he often refers to himself as an "Oh My" biologist  as in "oh my, look at this!" and "oh my, look at that!" He loves to kneel down close to the earth and, in his words, let the prairie talk to him.

CLARK:  Look at that leaf! Now you touch it with your fingers, see how it curls up behind my touch? This had a nice little red lollipop flower on it a few days ago. Its called Cat-claw Sensitive briar.  Kids love that. See this lead plant? It was used as medicine by Indians. It'd help a sore heal.

PHILLIPS:  Ranger Clark says that the prairie heals itself, too.

CLARK:   The prairie is amazingly resilient. There is probably no truer statement that that.

PHILLIPS:  Thanks to the Tallgrass Prairie National Preserve, any visitor to Kansas can have the opportunity to experience the wonder of the North American prairie -- if they simply get out of their cars, listen hard, and let the prairie talk to them. I'm Adam Phillips.

Music: Our World theme

That's our show for this week. We always welcome your comments. Email us at Ourworld is all one word. Or the postal address is -

Our World
Voice of America
Washington, DC 20237 USA.

Our World is edited by Rob Sivak. Our technical director is Gary Spizler. And this is Art Chimes, inviting you to join us online at or on your radio next Saturday and Sunday as we check out the latest in science and Our World.