By JAYSON JACOBY

Of the Baker City Herald

Judy Davidson can mesmerize 18 third-graders for more than an hour with tales of space rockets tall as skyscrapers, noises louder than everything except a nuclear bomb, and velcro-equipped forks.

Then she really shocks them with the diaper story.

andquot;If you’re going to be an astronaut you have to wear a diaper,andquot; Davidson said, provoking among her audience hysterical laughter of the sort a comedian desires but rarely receives.

It’s a true story, though.

The disposable diaper, Davidson said, is one of many convenience items we take for granted that NASA invented more than three decades ago, as the United States raced Russia to put the first footprints on the moon.

Others include mylar, which most of us know as the material in helium balloons, and the indispensable orange elixir of childhood, Tang.

Davidson, who teaches at Baker Middle School, brought her extraterrestrial story to third-graders at North Baker Elementary Monday.

She has been shrinking the limitless parsecs of the universe into the more confined spaces of Baker City classrooms since 1996, the year after she attended NASA’s Space Camp at Huntsville, Ala.

On Monday afternoon Davidson wore her light blue flight suit as she talked to students from Victoria Howard’s class.

She foreshadowed the diaper story with a magic trick.

First Davidson showed the students a pair of plain white styrofoam cups, the sort businesses have on hand for visitors who drink coffee.

Into one she poured several ounces of tap water.

Then she poured all the water from the first cup into the second.

Davidson asked the students which cup they thought the water was in.

They all pointed to the second cup.

Then she tipped both cups upside down. Not a drop of water fell from either one.

Whispers of andquot;Wow!andquot; and andquot;How’d she do that?andquot; echoed across the classroom.

Then Davidson revealed her secret.

The second cup, she said, contained sodium polyacrylate, a white powder that andquot;drinksandquot; 800 times its own weight, turning the liquid into a non-toxic gel.

The powder, she said, is the andquot;magicandquot; ingredient NASA used in the first disposable diapers.

And it’s still used today in the diapers on which millions of babys’ bottoms rest, Davidson said.

She encouraged the students to experiment with sodium polyacrylate’s magical properties, giving each group of students a piece of a diaper and a cup of water.

Once they had poured all the water onto the diaper, Davidson urged the students to tear apart the paper lining to expose the gel beneath.

Taylor McEnroe was ready even before his classmate, Will Barr, had dumped out the last drop of water.

andquot;Can we rip it open?andquot; McEnroe asked, apparently of anyone within earshot who might be authorized to say yes.

andquot;Ooooh, that’s gross!andquot; Barr said as he squeezed a hunk of gel that oozed like toothpaste through the gaps in his fingers.

andquot;Look at all that gel. Let’s have a food fight with it.andquot;

Davidson and Howard discouraged that plan, even though North Baker’s classrooms, unlike the space shuttle or the International Space Station, benefit from the mess-confining presence of gravity.

Howard’s students expressed awe at several points during Davidson’s story about the history of rocketry, starting with the invention of fireworks in China 2,400 years ago.

It wasn’t until the 1920s, though, that the American inventor Robert Goddard built the first rocket powered by liquid fuel, Davidson said.

andquot;It went 14 feet high and landed in his aunt’s cabbage patch,andquot; she said.

Everyone giggled at that.

A German scientist, Wernher von Braun, read about Goddard’s experiments and built even better rockets, Davidson said.

Unfortunately, von Braun’s boss, as several students deduced after a few hints from Davidson, was Adolf Hitler.

Hitler wanted rockets for one reason to carry bombs to England and the Third Reich’s other enemies.

But once World War II was over, von Braun came to America, where he worked with scientists who had the same goal for rockets as he did.

andquot;We didn’t want to put bombs on them, we wanted to put people on them,andquot; Davidson said. andquot;That’s what von Braun always wanted to do with his rockets.andquot;

The students seemed particularly fascinated by Davidson’s description of the Saturn 5 rockets, a hip-high model of which she displayed in the classroom.

Saturn 5’s propelled all nine of NASA’s moon missions.

Each Saturn weighed 7 million pounds and stretched 363 feet longer than a football field.

andquot;But it could only carry three people,andquot; Davidson said.

andquot;What?andquot; whispered a dozen little voices in unison.

Most of the rocket consisted of fuel tanks, Davidson said.

andquot;You wouldn’t want to ride in your car in the gas tank, would you?andquot; she asked.

The trio of astronauts rode in a tiny capsule perched at the top, like a star atop a Christmas tree.

Five engines lifted the rocket off the launch pad, then fell away into the ocean, Davidson said. Five more engines pushed the huge craft into orbit before they, too, were separated from the astronauts’ capsule.

Once the craft was in orbit, traveling at about 17,500 mph and with the rocket’s biggest, heaviest pieces jettisoned, a single engine was sufficient to drive the capsule to the moon at 25,000 mph.

When they reached the moon only two of the astronauts could ride in the craft that landed there, Davidson said.

The third had to stay with the other craft andquot;their ride home,andquot; as she put it.

Of the nine lunar missions, six actually landed on the moon’s surface, Davidson said.

The United States is the only country ever to put people on the moon.

andquot;That means only 12 human beings in the history of the world have got to walk on the moon,andquot; she said. andquot;And all of them were men not one single lady.andquot;

The first moon walk happened in 1969, the last in 1972 (not counting Michael Jackson).

Astronauts haven’t returned to the moon since.

One reason, Davidson said, is that the missions answered many of NASA’s questions about the moon, the most prominent being what it’s made of.

The samples astronauts brought back to Earth showed the moon, like our planet, is basically a big rock.

No green cheese.

Besides, Davidson said, sending astronauts to the moon is expensive about $10,000 for each of the Saturn 5’s 7 million pounds.

Students were impressed to learn that some astronauts drove a dune buggy on the moon.

But their awe turned to scorn when Davidson told them the lunar land speed record is a paltry 11 mph a velocity most probably have exceeded on a bicycle and a scooter.

Davidson also talked about the Space Shuttle, which can fly to space again and again but can’t get to the moon because it doesn’t carry enough fuel.

Like the Saturn 5, the Space Shuttle sheds several pieces during its trip to space, among them a pair of solid-fuel booster rockets and a larger aluminum tank.

The tank is as long as half a football field, Davidson said, but the trip back through the Earth’s atmosphere is a hot one.

NASA has recovered some of the tanks, she said, andquot;and all that’s left is a lump of metal about the size of a basketball.andquot;

Although astronauts can’t get to the moon on the Space Shuttle, the craft can do many things the Saturn 5 could not, Davidson said.

The shuttle, for example, can carry as many as seven astronauts. It also has a cargo hold big enough to carry a school bus, though instead of buses the shuttle usually hauls satellites and parts for the International Space Station the United States and 16 other countries are building.

Davidson said one of the more interesting experiments planned at the space station could allow astronauts to remain in space for many months without becoming ill.

Over the years scientists have discovered that astronauts who stay weightless for a long period suffer from weakened bones.

Davidson said a Russian cosmonaut who was in space for six months returned to Earth with bones so weak that when doctors lifted him from a stretcher several of his ribs broke.

One part of the space station is designed to spin, which will create andquot;artificialandquot; gravity, Davidson said.

Doctors hope that will prevent the bone-weakening effects of extended space travel.

If the experiment works and the technology can be incorporated into entire spacecrafts, it may be possible to send astronauts on the 1-year round trip to Mars, Davidson said.

Imagine how many diapers those pioneers will have to pack.