VOICE ONE:
This is Mary Tillotson.
VOICE TWO:
And this is Steve Ember with the VOA Special English programEXPLORATIONS. We tell about an experiment in space that shouldanswer a question. We report about NASA’s Cassini spacecraft that ison its way to Saturn. And we tell about the discovery of eleven moresmall moons that orbit the planet Jupiter.
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VOICE ONE:
A team of astronomers in Hawaii has discovered eleven more smallmoons that orbit the planet Jupiter. Thirty-nine moons now are knownto orbit Jupiter. That is nine more moons than the planet Saturnhas. For many years Saturn was thought to have more moons than anyother planet. Thirty moons have been seen around it.
The University of Hawaii teamleaders were Scott Sheppard and David Jewitt. Jan Kleyna ofCambridge University in Britain was also a member of the team.Mister Sheppard and Mister Jewitt have already discovered elevenother small moons in orbit around Jupiter. They made the earlierdiscovery in two-thousand.
VOICE TWO:
The discovery team used a three-point-six meter telescope inHawaii to make the latest discovery. This telescope is one of thelargest electronic imaging cameras in the world. It is owned byCanada, France and the University of Hawaii.
The team of astronomers used the ability of the large telescopeto gather images from a wide area around Jupiter. The team also usedcomputers to search the images to confirm the orbits of suspectedmoons.
The computers rejected space rocks that may have been travelingthrough the area. The team used the University of Hawaii’stwo-point-two meter telescope to continue to follow the orbits ofsuspected moons.
VOICE ONE:
Robert Jacobson is a scientist with NASA’s Jet PropulsionLaboratory in Pasadena, California. Brian Marsden is a scientistwith the combined research effort between Harvard University and theSmithsonian Institution. The two scientists say that all eleven ofthe moons travel in an orbit that is opposite to the direction thatJupiter turns.
The two scientists say these orbits are also very long and travelin many different directions. They said these unusual orbits areevidence that these small moons may have been large space rockswhich were captured by Saturn’s gravity. They said the moons mayhave been captured when Saturn was first being formed as a planet.
Scientists have been discovering moons in orbit around Jupiterfor almost four hundred years. The first moons of Jupiter to bediscovered are the four largest. They were discovered in the yearsixteen-ten by Italian scientist Galileo Galilei.
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VOICE TWO:
NASA reports that its Cassini spacecraft is in good condition andis speeding toward the planet Saturn. Cassini will arrive to beginorbiting Saturn on July first, two-thousand-four. The spacecraft waslaunched in October nineteen-ninety-seven. It has already traveledmore than three-thousand-million kilometers toward Saturn.
Robert Mitchell is NASA’s managerfor the Cassini-Huygens [HI-genz] program at the Jet PropulsionLaboratory in Pasadena, California. Mister Mitchell says the Cassinispacecraft has successfully completed a series of recent tests.These included test pictures taken of a star. The test was done tosee if the camera could see clearly.
The extreme cold of space had fogged the lens the camera seesthrough so clear pictures were not possible. NASA corrected byproblem by turning on heat devices built into the camera.
The cameras were warmed to a temperature just above freezing.Tests showed that more than ninety percent of the problem had beencorrected. Another warming period was begun May Ninth to furthercorrect the problem.
VOICE ONE:
The Cassini spacecraft was named in honor of the Italian-FrenchAstronomer Jean-Dominique Cassini. He was the scientist who firstsaw the famous rings that surround the planet Saturn. He discoveredfour of the planet’s moons in sixteen-seventy-five.
Cassini is an international project supported by the UnitedStates National Aeronautics and Space Administration, the EuropeanSpace Agency, and the Italian Space Agency. Several Europeanuniversities and major companies also are involved with the project.
Cassini carries the equipment needed to do twenty-sevenscientific investigations of Saturn and its moons. The hugespacecraft weighs about five-thousand-three-hundred kilograms.
VOICE TWO:
Cassini also carries a special device named for a Dutchscientist, Christiaan Huygens. He discovered Saturn’s largest moon,Titan. He lived and worked in the sixteen-hundreds.
The European Space Agency built the Huygens instrument. It willleave the Cassini spacecraft and parachute to the surface of Titan.It will take photographs, study the temperature and atmosphere anddo other scientific tests of the moon. The Huygens landing device isone of the most important instruments on the Cassini project.
Scientists have been interested in Titan for a long time.Saturn’s moon Titan is about the same size as the planet Mercury.Scientists say Titan is extremely interesting because it has anatmosphere. It has the only other known atmosphere in our solarsystem besides that of Earth.
VOICE ONE:
The flight of the Cassini spacecraft has been designed to gatherlarge amounts of information about Saturn and its moons, and returnthis information to Earth. The information will include a study ofSaturn’s atmosphere and its clouds.
The spacecraft will study the material found in Saturn’s rings.And it will study small particles collected by the spacecraft’sinstruments.
NASA says the information gathered by Cassini will be added towhat has been learned from past flights. This information will beused to plan flights far into the future.
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VOICE TWO:
We have a question for you today. When you plant a seed and itgrows, how does the plant know which way is up? How does the top ofthe plant know to push its way through the dirt and into thesunlight?
How does the bottom of the plantknow to grow down into the dirt? The question may sound funny, butscientists do not really know the answer. They do know that if youplant a seed up-side down, the plant will still grow in the correctdirection.
Scientists also know that sunlight is not the answer. Trees inthe far north still grow straight up, although the sun is neverdirectly over them.
Scientists believe the pull of Earth’s gravity is involvedsomehow. Yet, they are not sure just what the pull of gravity does.They do not know how a plant can feel gravity.
VOICE ONE:
Plant experts say they have two possible answers to the question.First, plant cells contain some fluid. The pull of Earth’s gravitymay pull the fluid downward enough to cause pressure on the cellwalls of a growing seed. This might serve as a sign that helps aplant decide which is up and which is down, and which direction togrow.
Scientists say another theory concerns the fact that all plantshave a material called starch. They say the starch material may bepulled down by gravity.
Scientists do not know which of these answers is correct.
VOICE TWO:
The question about how plants know which way to grow may beanswered this summer during the flight of Space Shuttle Colombia.The Colombia is to be launched on July nineteenth, for a sixteen-dayflight. It will carry a plant experiment to be done in theweightlessness of space. Scientists hope it will prove which theoryis correct. The experiment will involve a common plant called flax.
Once in space, a computer-controlled amount of water will startthe flax seeds growing. Unlike flax seeds growing on Earth, theseseeds will not feel the pull of gravity. The water and the starchmaterial in their cells will float rather than be pulled in anydirection by gravity.
After the plants have been growing for awhile, astronauts willcreate a false gravity using special magnets. Scientists know thisfalse gravity will affect only the starch material in the cells. Itwill not affect the water in the cells.
VOICE ONE:
Karl Hasenstein is the top researcher for the experiment. He saysthe question will be answered by changing the gravity effect on thestarch material. This will prove which one of the theories iscorrect. He says if the starch material theory is correct, the flaxseed plants should start to grow in the direction of false gravitycaused by the special magnets. If the way seeds grow is affected bygravity’s pull on the fluid in the cell walls, the magnets will haveno affect.
We will report the results of the experiment in a futureExplorations program.
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VOICE TWO:
This Special English program was written by Paul Thompson andproduced by Cynthia Kirk. This is Steve Ember.
VOICE ONE:
And this is Mary Tillotson. Join us again next week at this timefor another EXPLORATIONS program on the Voice of America.