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YOUR NEWSPAPER’S NAME HERE
YOUR NEWSPAPER’S NAME HERE
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
Written by: Julie Smead and Terri Darr McLean
Designed by: Trang Nguyen and Liz Manion
Photography and Illustrations by: PhotoDisc and Nova Development Corporation
Other images courtesy of NASA
What goes up ... must come down.....................................................................3
Gravity’s gurus....................................................................................................4
Defying gravity: Humans take flight ................................................................6
All aboard the ‘Vomit Comet’ .......................................................................8
Living in zero-g .......................................................................................12
Astronaut Dunbar achieves what others only dream of ..................14
© 2000-2006 KRP, Inc. All rights reserved.
NASATexas Space Grant Consortium
World Book EncyclopediaYoung Scientist
Which Way is Up? by Gail Kay HainesThe Science Book of Gravity by Neil Ardley
Gravity by Melvin BergerUp, Down and Around, the Force of Gravity by Milicent Selsam
Wonders of Gravity by Rocco FeravoloWhat is Gravity? by Fred M. King
The Astronaut Training Book for Kids by Kim LongSpace Stations by Stuart A. Kallen
The Lighter Side of Gravity by Jayant V. NarlikarGravity — The Universal Force by Don Nardo
Cosmic Science by Jim WieseThe Riddle of Gravitation by Peter G. Bergman
Observe your surroundings.Identify 10 ways gravity is at workin your life. Talk about how thingswould be different if there was lit-tle or no gravity on Earth.
Find a newspaper story aboutsomething that is related to gravi-ty’s effects. Share your story withthe class and explain how gravityis involved.
YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?
But gravity does more than make objectsplummet to the ground. It affects everythingyou do, from holding a hat on your head tokeeping you from flying off the face of theEarth as it travels around the sun at 66,000miles per hour. It’s gravity that makes Earthand the other planets orbit the sun in the firstplace.
Think about it. Almost everythingthat happens here — andbeyond — is in some wayconnected to gravity’s pull.You might say this wondrous force keepseverything in order.
What is gravity?People have been
pondering that questionfor thousands of years. It’snot that we don’t understandwhat gravity does; it’s that we’rehard-pressed to explain how it works.
What we do know is that gravity is a force ofattraction; a force that acts between all objectsbecause of their mass. Since the Earth is a verylarge mass, its gravitational pull is the dominantforce in our lives. All objects on or near Earth’ssurface are pulled toward its center.
We also know that gravity is one of thefour basic forces that hold the universetogether. Gravity is weaker than the otherthree — electromagnetic and the strong andweak nuclear forces — but it affects the waythe planets, moons, and stars are formed,how they move, and how they relate to otherheavenly bodies.
You can’t see gravity, but you canmeasure it. When you weigh an
object, you are measuringthe pull of gravity on it. The
bigger the object, thegreater the pull of gravityand the more the objectweighs.
The pull of gravitydecreases as you move
away from the center of amass. On Earth, for exam-
ple, you will weigh slightlyless on a mountaintop than you
do in a valley. And if you flew intoouter space, far away from Earth’s powerfulpull, you’d weigh nothing at all.
You can also observe gravity’s effects.Whether it’s the rise and fall of ocean tides orthat simple act of throwing a ball into the airand watching it fall, you can see gravity workits wonders every day.
Mass is often defined as the amount of matter an object
contains. An iron ball, for example, has more mass than a
rubber ball of the same size because the iron ball contains
more molecules packed closer together.
Most of us
learned at an
early age that when a
ball is thrown into the air it
falls back down to the ground.
(Unless, of course, it gets stuck on the
neighbor’s roof.) Most of us also learned
that this phenomenon is caused by gravity —
a powerful force that pulls things down to Earth.
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
The earliest theories were basedon religious beliefs and suggestedthat the Earth was the center of theuniverse. All heavenly bodies, manybelieved, were held in orbit aroundour planet by an invisible force.
The Greek philosopher Aristotle,for instance, maintained that all heav-enly bodies — planets, stars, moons— were encased in invisible spheresthat ran through the sky. Thosespheres, he said, kept them in theirorbits around the Earth. This theory ofan Earth-centered universe becameknown as geocentric.
Curious about why objects that arethrown into the air fall to the ground,Aristotle also considered the concept ofan Earth-based force. But like many
others, he neverconnected it withthe motions of thecelestial bodies.And although henever conductedany experimentswith falling objectsand he wrongly con-cluded that heavierobjects fall fasterthan lighter ones, hisviews would gounquestioned forhundreds of years.
Copernicus, a Polish astronomer, wasthe first to propose that the Earth andother planets revolve around the sun. But
he, too, failed to see a relationshipbetween plan-etary movements and theforce that pulls things downward to Earth.
The legend of the Leaning Tower
Italian physicist Galileo added weight tothe sun-centered, or heliocentric, train ofthought after discovering in 1610 that theplanet Jupiter had four moons thatrevolved around it. This discovery led himto conclude that all celestial bodies did notrevolve around Earth and that the otherplanets might give off invisible forces, too.
At the same time, Galileo figured that ifAristotle and others had been wrong aboutan Earth-centered universe, they might bewrong about other things, including the ideathat heavier objects fall faster than lighterones. He decided to test Aristotle’s theory.
As the story goes, Galileoclimbed to the top of theLeaning Tower of Pisa inItaly and dropped twoballs of differentweights at the sametime. To the surpriseof the crowd below,the balls hit theground simultane-ously. Many of themrefused to believewhat they had seen.
There is no actual evi-dence that Galileo conduct-ed his experiment off the Leaning
Tower. Many people believe he insteaddropped objects of different weights downinclined planes. Regardless, his experimentwith falling objects was the first to test andmeasure the force of gravity.
Galileo also proved that objects gainspeed as they fall. But even this famed scientist failed to establish a relationshipbetween the mysterious force that pulledthings toward Earth and the force thatkeeps the planets in orbit.
A closed school; an open mind
Twenty-three-year-old Isaac Newtonwas an undergraduate at CambridgeUniversity in England in the late 1600swhen an outbreak of the plague forcedmany students to go home for the winter.But while his classmates took a break,
Newton spent his time contem-plating the universe.
And contemplate hedid! In just a few
months, Newton man-aged to come up withtheories that wouldsolve the mystery ofgravitation and howit holds the universetogether. He became
the first to show thatthere is a connection
between the invisibleforce we now call gravity and
the way the planets move.
Copernicus
Galileo
Some of the greatest minds of all time devoted their lives to studying the
mysterious force of gravity. These renowned philosophers, astronomers,
and scientists made great strides in helping people understand how gravi-
ty holds the universe together.
With a partner, conduct someresearch on Aristotle, Copernicus,Galileo, or Newton. Imagine thatyou have the opportunity to inter-view the person you researchedand come up with 10 reporter’squestions to ask him. Role-playan interview for the class.
Isaac Newton was also a mathe-matician. At the same time hedeveloped his theory about gravi-ty, he invented a new kind ofmath to prove that theory. Do youknow what the system of math iscalled? Do some research to findout. In what ways is this type ofmath used today?
A simple mathematical formulahelped Newton explain muchabout our universe. Using yournewspaper, find references to atleast five instances where math isbeing used in everyday life. Whatconclusions can you draw?
Much of what people initiallybelieved about the universe wasrelated not only to the study ofastronomy but also to the study ofastrology. Astrologyis concerned withhow the heavenlybodies influencehuman beings.Although there is no scientific evidence to support astrology’sclaims, many people today studyastrology for entertainment. Thehoroscope in the daily newspaper,for instance, lists the signs of thezodiac and makes predictions foreach sign, based on the positionof the planets. Find your newspa-per’s horoscope and your birthsign. What’s in store for you
today? For fun, rewritethe horoscope withyour own make-believe predictionsfor the day.
Thanks to Newton’s ideas aboutgravity, scientists have been ableto learn even more about our universe. One of the things theyhave calculated is Earth’s escapevelocity, or the speed with whichan object must travel to escapegravity’s pull. Earth’s escapevelocity is 7 miles per second.How many miles per hour wouldan object have to travel to escapeEarth’s gravity?
YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?
Newton claims to have formulated his theory, in part, by watching an apple fall froma tree. This simple act caused him to ques-tion how far the force of gravity reaches and,eventually, to realize that the force thatcaused the apple to fall could hold the moonin its orbit around the Earth ... and the Earthin its orbit around the sun ... and so on.
Newton’s ideas became known as the theory of universal gravitation. The theorystated that every piece of matter — big andsmall — attracts every other piece of matter. It further stated that this force of attractionbetween two objects is directly related to thesize of their masses, as well as the distance
between them. Newton even came up with awhole new kind of math to prove his theories.
Newton’s theory revolutionized the scien-tific world. It not only solved the mystery of gravitation, it laid the groundwork for modernscience.
Off in a new directionSome people scoffed at Newton’s theory;
others embraced it. But no one reallyexpanded on it until 1915, when AlbertEinstein came up with his general theory ofrelativity. Einstein said that gravitation is aneffect of the curvature of space and time.
Don’t worry if you’re scratching your headand wondering what that means. Einstein’sideas are difficult for many people to under-stand. Basically, he proved that strong gravi-tational forces have the ability to bend lightand curve space. Earth’s gravity is too weakto do that. But the sun and some stars exertenough gravitational pull to wield such power.
Einstein’s theory helps astronomers studydistant stars and physicists to understandmotion. His work also aids astronauts as theyplan their space travels.
One of the things Isaac Newton’s theory of universal gravitationenabled scientists to do was figure the masses of other heavenly bodies. Once they figured out the mass of the Earth and moon, theycould calculate the mass of the sun, for instance. Turns out, the sun’smass is about 333,400 times the mass of Earth. In other words, youwould need 333,400 Earths to balance out the mass of our sun.
SEEING IS BELIEVINGLegend has it that many people watched Galileo conduct his experiment off the
Leaning Tower of Pisa but still refused to believe that heavy and light objects fall atthe same speed. After all, they had long been taught otherwise.
Try these simple experiments to “see” if you believe:
• You will need two balls of different weights — a ball bearing and a light plastic ball,for instance. You will also need a metal tray. (To expand the experiment, you willneed modeling clay.)
• Now, standing up, hold the two balls above the metal tray (make sure your handsare level). Drop the balls at the same time and listen as they hit the metal tray. Dothey hit at the same time?
• If you want to see if the heavier ball hits the ground with greater force, roll out mod-eling clay on the metal tray. Drop the balls again, then compare the impressionsthey leave on the clay. What conclusions can you draw?
• One step further: What would happen if you used a very light object, such as asheet of paper, and an entire magazine in the above experiment? Research theeffect of air resistance on a falling object.
— Adapted from The Science Book of Gravity by Neil Ardley, and Cosmic Science by Jim Wiese.
Newton
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
The ancient Greeks, for instance,dreamed of fashioning handcrafted wings tohelp them overcome gravity. As one legendgoes, Daedalus, an architect and inventor,made two sets of wings — one for him andone for his son, Icarus. The pair glued on thewings and flew up toward the sun.
Daedalus warned Icarus not to fly too highbecause the sun might melt the glue. ButIcarus ignored his father’s words and soaredeven higher. As predicted, the sun melted theglue of Icarus’ wings, and the young man fellto his death.
The moral of the story? Many who heardit believed humans were not meant to fly.
Still, many people refused to believe thathumans couldn’t some day take flight. Thefamous Italian artist Leonardo da Vinci, whowas also an engineer, made some of the firstdrawings of flying machines in the 15th cen-tury. But the technology to make themachines work was not available.
People began to seriously experimentwith flying machines in the late 1700s andearly 1800s. They built hang gliders thatlooked like birds and balloons filled with hotair. Later, large airships called dirigibles werealso used to help people in their attempts todefy gravity.
Doing it the Wright wayInspired by early hang gliders, brothers
Orville and Wilbur Wright built the first successful airplane in 1903 in Kitty Hawk,N.C. It was a two-winged plane with a small,gasoline-powered engine. When Orville flewthe motorized vehicle to a distance of 120feet, modern aviation was born.
Few people took notice of theWright brothers’ accomplish-ment, but that didn’t stopthem from working toimprove their invention.Two years later, theybuilt an airplane thatcould fly for morethan 30 minutes at atime.
Eventually, thebrothers captured people’s attention withtheir airplane’s flying ability. Soon, other inventorsbegan working on improving
airplane design. By the 1950s, pas-senger planes with jet engines
gave more people theopportunity to experi-
ence flight and to over-come gravity’s hold.
An out-of-this-world experience
While the Wrightbrothers were perfecting
their flying machines, others were setting their
sights higher. They dreamed of
Orville Wright Wilbur Wright
There are many things about gravity that have fascinated people throughout the
years but none as much as finding a way to break free of its mysterious hold.
YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?
SEEING IS BELIEVING
You can defy gravity — without ever leaving your classroom. Try this experiment:
• You will need a plastic, 2-litre soft drink bottle with screw-on top, a bowl, water,and scissors.
• With adult supervision, use the scissors to poke several holes in the bottom of thesoft drink bottle. Stand the bottle in the bowl and quickly fill it with water. Screwthe top on immediately.
• Lift the bottle and see what happens. No water flows out of the holes because theair beneath the bottle pushes up against the holes, working against the force ofgravity and keeping the water in the bottle.
• Now, unscrew the top. What happens?
• By removing the top, you are allowing air to enter the bottle and push down on thewater. This causes the water to flow out of the bottle.
— Adapted from The Science Book of Gravity, by Neil Ardley
Two effects of gravity that an airplane must overcome are weight
and drag. Weight, of course, is the effect of objects being drawn toward
the center of Earth by the force of gravity. Drag is the effect of air
pressure on an object. Engines and propellers give an airplane the
ability to overcome drag, while an airplane’s wings, with their curved
tops and flat-bottoms, give it enough lift to overcome its weight.
Myths and legends —fictitious stories thatoften attempt toexplain the phe-nomena of nature— are filled withreferences tohuman attemptsto fly. Do researchto find an exampleof such a myth orlegend. Turn itinto a newspaperstory featuring thefive Ws: who, what,when, where, andwhy. What does themyth or legend tellyou about early ideasconcerning flight? Discuss.
Write newspaper headlinesthat might have appeared fol-lowing five major events in avi-ation history. Compare yourheadlines with those of yourclassmates. Be prepared toexplain your thoughts.
The “space race” was a very realrace between the former SovietUnion and the United States. Whenthe Soviets launched Sputnik 1 in1957, America was determined tocatch up. And it did! After creatingthe civilian space agency NASA,the United States made greatprogress in establishing itself as thefrontrunner in space exploration.Find out more about NASA, includ-ing watching for newspaper storiesabout the agency and its programs.Share a newspaper story with theclass that proves the United Statesremains a leader in space explo-ration.
A variety of animals have madeaviation history, including Laika,the first dog in space. Laika’s flightaboard the Soviet Union’s Sputnik2 proved that animals could sur-vive the effects of reduced gravity.Write an editorial that would per-suade NASA to send your pet (orfictional pet) on the next spaceshuttle mission. Don’t forget:Editorials are opinions based onfacts. Be convincing!
As a class, watch a movie with aspace theme, such as Star Wars,Star Trek, or The Right Stuff. Thenwrite a newspaper-style review ofthe movie. Discuss your thoughtswith the class.
escaping gravity’s pull altogether and travelinginto outer space.
In fact, eight years before Orville and Wilburmade history, a Russian math teacher beganpublishing articles on space travel. KonstantineTsiolkovsky was probably the first to suggestthat the only way to completely escape gravity’spull was through the use of rockets.
Rockets had been used in ancient times forfireworks and, later, in warfare. Rocket propul-sion was provided by black gunpowder.
But Tsiolkovsky realized that gunpowder wasnot powerful enough to make an object reachEarth’s escape velocity — 7 miles per second.He suggested a mix of liquified hydrogen andoxygen.
American rocket engineer Robert Goddardtook Tsiolkovsky’s suggestion to heart and in1926 began launching liquid-fuel rockets.Further advances followed, and in 1957, the for-mer Soviet Union launched the first liquid-fuelrocket into outer space.
With this accom-plishment, the “spaceage” began. Today,with space probes,space shuttle flights,satellites, and spacestations, we are nolonger held tight toEarth by gravity’srelentless tug.
Dr. Robert Goddard
Dr. RobertGoddard,
standing nextto his liquid-
fueled rocket,1926
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HEREWHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
Technically speaking, the KC-135A does not produce periods
of zero-gravity; it produces peri-ods of microgravity, or .001 to.0001 times the Earth’s gravity.However, that fact doesn’t stopmost people from describing
their experience aboard the KC-135A as pure and simple weight-
lessness. In fact, NASA nick-named the KC-135A aircraft the
“Weightless Wonder!”
Microgravity =micro comes from the Greek
mikros meaning “small.”
• Moon = 1/6 Earth’s gravity• Mars = 1/3 Earth’s gravity
Zero-gravity =the absence of gravity.
Weightlessness =a synonym for zero-gravity.
By Julie SmeadTwice a year, nearly 100 teams of collegestudents from around the country travel toEllington Field and the Johnson SpaceCenter to participate in NASA’s ReducedGravity Student Program and gain firsthandknowledge of the effects of living and work-ing in microgravity. A few lucky journalistsare also invited, of which I was one.
Once I checked in at Hangar 990, home ofthe officially named KC-135A aircraft, Iunderwent some of the same training thatastronauts do, including lectures on thehuman body and a simulated flight inside thedreaded altitude chamber. They wanted us tobe able to recognize the effects of hypoxia,an abnormal condition resulting from adecrease in oxygen supplied to body tissue.
After two days of training, we were readyto fly. Sporting an olive drab flight suit withscores of zippered pockets, I climbed the air-plane’s steps for my once-in-a-lifetime ride.I’d eaten oatmeal for breakfast, the food rec-ommended by Vomit Comet veterans for itsblandness and “stick-to-your-ribs” quality. If Iwasn’t ready now, I’d never be.
At the top of the stairs it occurred to methat I was preparing to add my name to a veryspecial list. In the entire world, only a handfulof folks had been lucky enough to fly aboardthe KC-135A. Soon, I would be one of them.
I joined the other passengers inside andbuckled into the seats at the rear of theplane while Physiological Training OfficerC.K. LaPinta doled out extra barf bags. Itook several and stuffed them into my pock-ets, hoping for the best. Several of the stu-dents on the flight fashioned barf bag bou-tonnieres out of the little white bags, arrang-ing them in their front top pockets. A largetin filled with Tums antacid tablets, TootsieRolls, chewing gum, Jolly Ranchers, andearplugs made the rounds.
The next thing I knew, we were cruisingover the Gulf of Mexico on our way to theweightless unknown. Two NASA pilots andthree NASA photographers, donning theirblue flight suits, hearing protection, and head-phone headsets, busied themselves withpreparations. Soon, we were headed for ourfirst parabola, the flying arch formation thatproduces brief periods of weightlessness.
I love roller coasters.Airplane rides never bother me.I don’t get carsick.And the few times I’ve been on a boat in the ocean, the word
“sick” didn’t enter my mind.So when I was asked to accompany some college students to
Houston, Texas, for a weightless ride aboard NASA’s WeightlessWonder, a.k.a. the Vomit Comet, I agreed immediately. Me? Motionsick? Ha! I’ll float weightless blindfolded ... or something like that.
Continued on page 11
YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?
The KC-135A aircraft is the military version of a Boeing 707. On the outside it looks like an average pas-senger plane, but inside there are fewer passenger seats, no overhead storage bins, and definitely no drinkcarts. The airplane’s interior has been gutted and padded to provide passengers with a safe, spacious areain which to work.
The KC-135A produces brief periods of weightlessness by flying arch formations called parabolas. Tounderstand the parabola concept, think of a roller coaster ride or a hilly road in your neighborhood thatmakes your stomach flip. Remember how your body lifts out of the seat when the roller coaster car or theautomobile crests the top of the hill? On a much larger scale, that’s what happens inside the KC-135A —about 40 times in a row!
To give pilots plenty of flying room, the KC-135A is flown out over the Gulf of Mexico. Traveling at about450 miles per hour, the pilots steer the aircraft up — almost vertically — until the plane reaches a height ofabout 32,000 feet. Then, the pilots pull back, or slow down, the engines. Performed correctly, this pull backproduces 20 to 25 seconds of weightlessness. Then the plane heads back down to do it all again.
After the zero-gravity, or zero-g, portion, pilots direct the nose of the aircraft down, creating a 2g force,or two times the force of the Earth’s gravity. Inside the plane at this time, passengers weigh twice their nor-mal weight and find it difficult to lift their bodies off the floor. The heavy pressure subsides once the pilotsreach 24,000 feet. Then, they turn the nose of the plane back up and do it all again. (And again, and again...)
The KC-135A usually flies 40 parabolas in about 45 minutes. During this time, the gravity receptors insidethe inner ear become confused while the stomach and intestines are expanded, then squashed over andover. Given such conditions, it’s hard to imagine anyone NOT becoming ill aboard the KC-135A. But somenever do.
Would you?
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HEREWHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
Continued from page 8
“Two minutes!” announced pilot and zero-g specialist John Yaniek.
I sat on the floor nervously clutching mycamera.
“OK, get ready!” he shouted. “Here we go.”We zoomed up the arch of the first parabo-
la, the engines screaming with turbo power.Anticipation glowed from every face. Speed?About 450 miles per hour. Time? About 20seconds away from weightlessness.
As I adjusted my earplugs to better mufflethe screaming engines, Yaniek made therounds again. Across the floor from me, twostudents smiled and waited, braced at theedge of the experiments they would conductduring the periods of weightlessness.
“OK everybody,” Yaniek said seriously.“Here it comes!”
The screaming engines stopped. In slowmotion, everything started to float. My cam-era rose first, then my arms, legs, and rearend. I kicked like a swimmer, propellingmyself to the ceiling where I bounced andturned upside-down. I felt giddy.
Inside my stomach, 2,000 butterflies werestruggling to escape. My senses — direction,weight, and balance — were completely outof whack. My body was freaking out — ablissful panic — and all I could do was laugh.
Glancing around, I saw the students strug-gling, too. Most wrestled with floating exper-iments, securing runaway wires, cords, andother scientific pieces that had floated loose.Crazy smiles lit every face. Then, after whatseemed to be about five seconds of weight-lessness, Yaniek started shouting again.
“We’re coming out!”To avoid painful free-falls from the ceiling,
Yaniek warned us each time the weightlessportion was about to end. I steered my heli-um-like body back to the floor and lay on myback. This was the recommended positionfor the 2g portion of each parabola. Theengines screamed as the aircraft plungedbeneath me. The force of gravity doubled andpressed down on my chest.
The veteran NASA crew members tookthe 2g portion standing straight up, armsakimbo, ready to react with just the right stuff.In their official NASA flight suits, they lookedlike bright blue buoys in a sea of olive drab.
Twenty seconds later, I was floating againand feeling a bit more in control. For fun, Iswam along the ceiling, then turned upside-down to take photos of the students beneathme. The slightest movements caused largereactions, and I bumped into a NASA pho-tographer while hovering precariously over anexpensive-looking experiment. During oneweightless episode, I lay still on my back andallowed myself to rise like the lovely assistantin a magic show.
On both sides of the airplane, enthusiasticstudents gave their experiments good old-fashioned college tries. I was impressed withtheir tenacity, despite the bizarre conditionsand floating paraphernalia. One male studentcontinued with this experiment while vomit-ing into a white bag. Another student tookfrequent breaks from her laptop computerproject to do flips in mid-air.
I made it past the lucky 13th parabola(there were 40 of them in all) before pulling abag from my pocket. I wasn’t the first to getsick, nor was I the last. After I emptied mystomach into the sandwich-sized bag, Ihoped to feel better. But I didn’t. Dr. LaPinta
Two students recuperate after their ride aboard the KC-135A.
A student wearing Xybernaut body computer
The screaming engines stopped.In slow motion, everything started to float.My camera rose first, then my arms, legs,
and rear end. I kicked like a swimmer, propellingmyself to the ceiling where I bounced and
turned upside-down. I felt giddy.
YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?YOUR NEWSPAPER’S NAME HERE WHAT’S UP WITH GRAVITY?
Students participating in thereduced gravity program workhard to design experiments thatwill be beneficial to NASA, as wellas to their own learning experi-ences. In small groups, design areduced gravity experiment thatyou would do if you were given theopportunity to participate in theprogram. Then, individually, write amock letter to NASA describingyour experiment and why youshould be allowed to ride aboardthe KC-135A to try it out.
Did you know that all the weight-less scenes for the 1995 film,“Apollo 13” were shot inside theKC-135A aircraft? Even afterspending several hours inside the“Vomit Comet,” actor Tom Hanksdidn’t vomit once! As a class, watch“Apollo 13,” paying particular atten-tion to the weightless scenes.Discuss your thoughts about themovie and whether the weightlessscenes seemed realistic.
Experiments really float up here!
Scene from the movie Apollo 13The author in midair wearing a stylish barf bag boutonniere! (Can you see that look of fear and excitement in her eyes?)
steered me to a seat at the rear of the plane,buckling me in and cooling my face with asmall battery-powered fan.
For the remainder of the flight, I sat andprayed for solid ground while the other “kills”joined me at the back of the plane, puking andcoughing. It was a space-age vomitorium.With each parabola, we “kills” floated miser-ably in our chairs against our seat belts, clutch-ing little white bags. During the 2g portion, wewere plastered into our chairs, grateful for thegravity that helped keep our vomit down.
As we suffered, we watched the othersfly and twirl about unaffected by the gut-wrenching ride. Experiments abandoned
long ago by sick students, the remainingpassengers somersaulted in mid-air, zoomedaround the cabin like super heroes or pouredliquid into the air to watch it form perfectfloating spheres.
At last, we landed at Ellington Field. Myfirst thought? “Gravity is good.”
Pale and shaky, I emerged from the air-plane and staggered down the stairs to theground crew assembled on the tarmac.Spotting one of the students who had been illon the plane, I asked about his experience.
“Truthfully? I hated it,” he said. “It was themost horrible thing I’ve ever had to gothrough in my life.”
But the student walking beside him waselated. “It was incredible! I loved everyminute of it. I’m going again tomorrow.”
After group photos were taken and warstories were told, I headed back to the hotelfor a nap. I was exhausted and couldn’tface food until late that evening.
The next day, some students flew againwhile journalists watched and waited.(Media were allowed to fly only once.) Ilearned later that one more “kill” on myflight would have tied with NASA’s all-timerecord of 14. The second day’s flight pro-duced just five.
Wimps.
WHAT’S UP WITH GRAVITY? YOUR NEWSPAPER’S NAME HERE
Assembly of the ISS began in 1994 withthe first docking of the space shuttle and theRussian Space Station Mir. By 2004, the ISSwill weigh 460 tons (on Earth, of course) andmeasure the length of a football field, includ-ing the end zones. The finished station willhave more than 100 modules, requiring 45separate delivery and construction missionsover 10 years. Space-walking astronauts willbuild and maintain the ISS by working withrobotic cherry pickers and cranes.
Space organizationsfrom Russia, Japan,Europe, Canada, and theUnited States have con-tributed to ISS construc-tion, making it the largestnon-military joint effort inhistory. This many-mod-uled orbiting space labora-tory will serve as home toscientists and astronautsfrom around our world.
The crew will live insidea habitation module andwork inside one of six sci-entific laboratories. TheUnited States, Europe,and Japan will each sup-
ply one experiment module and Russia willsupply three.
The ability to manipulate gravity, as wellas temperature and pressure, will allowresearchers to perform experiments andstudies aboard the ISS that are impossiblehere on Earth. Research will range from creating advanced industrial materials andcommunications technology to conductingmedical research.
Pass the Pepto, please!Before anyone can climb aboard the ISS
— or any space station — they have to getthere, and that’s half the battle. About half ofall space travelers experience a harrowingcondition called space sickness during thefirst few days of a mission. Its symptomsinclude persistent nausea and vomiting.
The technical name for this condition isspace adaptation syndrome, and it’s the
body’s natural reaction toreduced gravity, or micro-gravity. If you’ve ever expe-rienced car sickness, youhave some idea of whatspace sickness is like.
Microgravity also confus-es a person’s sense ofdirection. This is causedwhen the balance mecha-nisms in the inner ear getout of whack.
In addition, after severaldays or weeks in space, aperson’s body experiencesdeconditioning. In otherwords, muscles get weakand the heart and blood
At NASA’s Mission Control Center in Houston, a huge digital map tracks the
International Space Station as it orbits the Earth. On the map, the ISS is about the
size of a softball. In our night sky, it’s a star that grows brighter with each additional
piece assembled by astronauts. The ISS is the world’s largest scientific experiment,
and one day people will be living and working inside its impressive modules.
Astronauts floating inside Space Lab
vessels get lazy. Demineralization, or weak-ening of the bones, can occur after manymonths of space travel. Vigorous exerciseand special diets can help prevent decondi-tioning and minimize demineralization andare part of any routine in space.
A day in the life of ...Space inhabitants, like those who will
eventually live aboard the ISS, must copewith living in a weightless environment dayafter day. Even the simplest tasks become amajor challenge when everything — includ-ing your body — is weightless. Let’s take alook:
SleepingLiving quarters in space are usually quite
small, even aboard such a massive structureas the ISS. For those who can’t get used tosleeping in midair, special sleeping back-packs fixed to walls or horizontal beds withstraps are available. Some space travelersmight actually prefer floating while theydream. Would you?
BathingWhen it’s time to freshen up, today’s
astronauts can take a shower. To keep waterfrom floating around, however, they mustvacuum it out of the special stall as they soapand rinse. As you might have guessed, manyastronauts bypass this complicated proce-dure and take sponge baths instead.Eventually all water aboard the ISS — bathwater, dish water, even urine — will be treat-ed, purified, and recycled to provide a con-stant, reusable source in space.
EatingSpace food once consisted of frozen food
with the water removed that was packaged inplastic tubes so it wouldn’t float away. Justadd water and squeeze.
Today, some space shuttles have menuswith up to 125 foods and beverages – most-ly ready-to-eat meals that can be heated inthe shuttle’s galley, or kitchen. Special tableswith foot loops allow the astronauts to sitwhile eating.
D r i n k i n gwater is pro-vided by fuelcells that pro-duce purewater whileg e n e r a t i n gelectricity forthe spacevehicle. Onlonger mis-sions, watermust be recycled and used for such choresas washing clothes.
Beating boredomAlthough there are many important tasks
to keep astronauts busy in space, recreation-al activities are a must, especially on longflights. Many enjoy sightseeing out space-craft windows. They also read, listen tomusic, play computer games, and exercise— with special equipment that won’t floataway, of course.
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Living in a weightless environ-ment presents many challenges.Keep a list of your everyday activ-ities. How would you do thingsdifferently in space? Discuss thechallenges in small groups.
Recreational activities are impor-tant to the physical and mentalwell-being of people who travel orlive in space for long periods oftime. Look through your newspa-per for activities you could do inspace. Find at least one activityyou couldn’t do in space becauseof reduced gravity.
Choose a sport from your news-paper’s sports section anddescribe how it might be playedin a weightless environment.Include special equipment, cloth-ing, or other items that might beneeded to overcome the effectsof reduced gravity.
Send a comic strip character tospace. With a partner, rewriteyour favorite strip with the charac-ter(s) in a weightless environment.Make a bulletin board display fea-turing the rewritten comic strips.
Pack your bags for an extendedstay on the International SpaceStation. Cut out 10 items fromtoday’s newspaper that you musthave to make the best of yourvisit.
SEEING IS BELIEVINGWhen people travel in space, are they really weightless? In Jim Wiese’s book,
Cosmic Science, he suggests the following experiment to find out:
• You will need a pencil, an 8-ounce paper cup, two rubber bands (at least 1⁄2 inchlonger than the side of the cup), a small paper clip, tape, and two coins or metalwashers.
• Using the pencil, make a small hole in the center of the cup’s bottom. Hook the rubber bands onto the paper clip. From inside the cup, push the paper clip throughthe hole, keeping the ends of the rubber bands inside the cup. Spread the paperclip apart on the outside of the cup so it can’t be pulled back through the hole.
• Now, set the cup upright and pull each rubber band to its longest length withoutstretching it. Tape a coin (or metal washer) to the end of each rubber band so thecoins hang over the outside edge of the cup. (Don’t tape coins to cup.)
• Finally, hold the cup upright at eye level, then drop it. What happens?
• Before the cup is dropped, the coins are held in place outside the cup because theforce of gravity and the force of the rubber bands act equally upon them. But whenthe cup is dropped, the coins are pulled inside. That’s because both the coins andthe cup are accelerated at the same rate by gravity, creating the effect of no gravity. The only force acting upon the coins, then, is the force of the rubber bands,which pulls the coins into the cup as it falls.
When astronauts orbit the Earth, they, too, are falling at the same rate as theirspacecraft, which creates the feeling of weightlessness.
The term microgravity, or zero gravity, does not accurately describe
the condition that exists when traveling in space. In truth, the gravity on
a spacecraft is only slightly less than the gravitational pull on Earth. The
feeling of weightlessness comes from the fact that a spacecraft and its
contents continue to fall toward Earth while in orbit. But the craft trav-
els so fast that Earth’s surface curves away as the vehicle falls toward
it, seemingly eliminating the weight of everything inside.
Frozen space foods
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Growing up in the 1950s during the firstdays of the “space race,” Dunbar was captivated by Sputnik. The first man-madevehicle to orbit the Earth, Sputnik waslaunched by the Soviets in 1957, kicking off arace between the Americans and the Sovietsto see which country could put a human intoorbit first. Americans were crazy about space,and Dunbar’s family was no exception.
“At the time, I had no rational reason forwanting to become an astronaut except thatit captured my imagination and my dreams,”Dunbar said.
“When Sputnik was launched we’d go outand look for it in the sky,” Dunbar said. “Welived out in the middle of nowhere, so youcould see it against a background of stars.”
Dunbar grew up on a cattle ranch inWashington’s Yakima Valley, an area famousfor its apples. Her father was a homesteaderwho won his ranch in a land raffle for WorldWar II veterans.
‘I want to be an astronaut’After graduating high school in 1967,
Dunbar went to the University of Washingtonto study engineering. A beneficiary of a government program, she paid for collegewith a National Defense Loan. Such loansmade lucrative engineering careers possiblefor many students, especially women, who otherwise might not have been able to affordan education. According to Dunbar, careeroptions for women were limited.
“When I told my professors I wanted to bean astronaut, half of them said I was crazy. Butthe other half were very supportive,” Dunbarsaid. “I wouldn’t be here today without themor without the support of my parents.”
Dunbar received bachelor’s and master’sdegrees in ceramic engineering from the
University of Washington in 1971 and 1975.One of the oldest engineering disciplines,ceramic engineering gave Dunbar a solidbase from which to launch her aerospacecareer.
“When most people think of ceramicsengineering they think of pottery,” Dunbarsaid. “But most materials that don’t fall intothe metal or plastic categories fall underceramics.”
Soon after her first job as systems analystfor Boeing Computer Services, Dunbar wasrecruited by Rockwell International SpaceDivision in Palmdale, Calif., to help build thefirst space shuttle for NASA.
“The challenge was to design a light-weight tile that’s mostly air — 90 percent air— with glass fibers that melted at tempera-tures above 2,000 degrees Fahrenheit,”Dunbar explained. “And the tiles needed tobe able to fly many times.”
Although advancements have led to somechanges, the core tile used on the space
shuttle today is basically the same as thatproduced by Dunbar and her team in the1970s. In fact, some of the tiles on today’sspace shuttle are original, she said.
“It was so exciting to see that first vehiclecome together and then eventually fly in it —twice,” Dunbar said.
The dream comes trueIn 1981, Dunbar became an astronaut.
But the sky wasn’t the limit for her. She even-tually earned the title Dr. Dunbar by complet-ing her doctoral studies in biomedical engi-neering at the University of Houston.
“Bone’s a ceramic material,” Dunbar said.“And I wanted to study the effects of weight-lessness on human beings.”
By blending ceramic engineering with stud-ies of the human body, Dunbar opened herselfup to more and greater research possibilities at NASA. She was particularlyintrigued by the loss of calcium in Skylab astro-
Osteoporosis is a gradual weakening of the bones that occursprimarily in older women. As with many NASA research projects,the ongoing research on calcium loss by Bonnie Dunbar and otherNASA scientists has been used to help the general public.University researchers around the country often partner with NASAto develop new ways to fight this and other diseases.
Astronaut Bonnie Dunbar
Bonnie Dunbar wasn’t like many other girls. While her female classmates played
with dolls and cooking sets, Dunbar spent hours gazing up at the Milky Way.
At age 9, she announced her plans to become an astronaut.
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nauts who had spent three months in orbit.“I wanted to learn if their loss of calcium
was the same as that of osteoporosis in theelderly,” said Dunbar.
“When we walk, we put a lot of force onour bones due to gravity,” she explained.“When you take that gravity off, it’s like beingbedridden or elderly.”
In 1995, Dunbar served as MissionSpecialist on Atlantis, the first U.S. spaceshuttle to dock with the Russian SpaceStation Mir. Dunbar and her crew performedmedical evaluations on the returning Russiancosmonauts, who’d lived in orbit for threemonths. The tests examined the effects ofprolonged weightlessness on the heart,lungs, bones, muscles, and immune system.She said some astronauts can lose up to 9percent of their bones’ calcium after justthree months in space.
“We’re still understanding these mecha-nisms,” Dunbar said.
Fifty days and countingSince becoming an astronaut, Dunbar has
spent 1,208 hours, or 50 days, in space. In1994, she trained with cosmonauts in StarCity, Russia, as a back-up crew member forU.S. astronaut Norm Thagard. She didn’t endup flying in place of Thagard, but soon aftershe joined the space shuttle mission thatdocked with Mir to pick him up.
Between space missions, Dunbar serves
as adviser to the Reduced Gravity StudentProgram at NASA’s Ellington Field andJohnson Space Center. She also teachesmechanical engineering at the University ofHouston.
Dunbar advises students interested inaerospace careers to take plenty of math andscience courses. According to Dunbar, stu-dents who don’t take calculus, physics, andchemistry in high school lock themselves outof 70 percent of all careers. She emphasizesalgebra, calculus, physics, trigonometry, andgeometry as high school basics.
“The starting path to math is algebra,”
Dunbar said. “That’s the key. You’ve got to bein algebra no later than seventh or eighthgrade.”
“I also tell kids that 60 percent of astro-nauts and NASA pilots have college degreesin engineering.”
Asked to give the highlight of her career,Dunbar says:
“It’s hard to say because every flight is likea child: You can’t pick between them. They’reall different and I’ve had a great time on eachone.
“I think the highlight for me is just beingable to do what I do in my lifetime. I can’t fly
forever, I know that. But I hope my nextcareer is just as rewarding.
“I couldn’t have imagined such a greatlife.”
Astronauts must be very good atmath and science.Write a classifiedad describingall the qualifi-cations anastronautmust meet.
There are two typesof NASA astronauts:pilot/commander astronauts andmission control/scientist astro-nauts. Search your newspaper’s classified ads for job descriptionsrequiring the same qualificationsas a scientist astronaut. Explainwhat sort of work your choicesmight do. Hint: About 60 percentof such astronauts are engineers.
NASA’s Space Flight ParticipationProgram offers the opportunity forspace travel to many Americans,including civilians. Write a mockletter to NASA describing whyyou should be the first teen-agerin space.
If, like Bonnie Dunbar, you couldgrow up to be what you’ve alwaysdreamed of, what would you be?Write a brief essay about yourdream career.
Pick a comic strip character you think would make a goodastronaut. Design a newspaper ad promoting this character forthe next major space mission.
It takes more than an iron stomach to become an astronaut.
Dunbar aboard Space Shuttle Endeavour
Dunbar suits up for Atlantis mission.
Crew Insignia for Space Shuttle Atlantis
WHAT EXACTLY IS “THE RIGHT STUFF?”
PILOT ASTRONAUTS
Educational Minimum:Bachelor’s degree in engineering,biological science, physical science,or mathematics
Post-graduate:Not required
Flight time:1,000 hours pilot-in-command time in jet aircraft
Vision:20/70 or better, uncorrected20/20 corrected in each eye
Blood Pressure:140/90 blood pressure in a sittingposition
Height:Between 64 and 76 inches (roughly 5 feet, 3 inches to 6 feet, 3 inches)
MISSION SPECIALISTS
Educational Minimum:Bachelor’s degree in engineering,biological science, physical science,or mathematics
Post-graduate:3 years’ related professional experi-ence and/or master’s or doctoraldegree in place of experience
Flight time:Not required
Vision:20/200 or better, uncorrected20/20 corrected in each eye
Blood Pressure:140/90 blood pressure in a sittingposition
Height:Between 58.5 and 76 inches (roughly4 feet 8 inches to 6 feet, 3 inches)
Shuttle Atlantis launch — 1995
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