“We’ll get to blowing things up here in a minute, don’t worry.”
Earl Mullins, founder and president of the Space Museum, said this to reassure the assembled parents and guardians of more than a dozen kids who attended Bonne Terre Memorial Library’s fun and educational event at Heritage Hall.
Several long folding tables held a curious collection of tools for experiments that would demonstrate the basic principles behind rockets and humankind’s trips to space. Mullins had a twinkle in his eye as he joked about potential explosions in the name of science, but he was very serious about his mission to encourage youngsters to embrace curiosity and the world of science.
“Science is really not that difficult,” Mullins said. “It all comes down to two words: observation and imagination. Once you see things with your eyes, you can use your imagination to think about how you can use what you’ve learned.”
The Space Museum’s demonstration was part of the public library’s summer reading program, themed “A Universe of Stories.” It was clear within five minutes of the presentation that Mullins had many interesting stories to tell and a lot of experiments to show.
“The science of rocket engines goes so far back, it’s 1,900 years old. There was a Chinese scientist that was looking for a formula to live forever. But when he was heating certain chemicals up, he got a result he wasn’t bargaining for. Can you tell me what happened?” he asked the crowd.
“Ka-boom,” a grownup said helpfully.
“Ka-boom! Exactly!” confirmed Mullins. “But instead of quitting, like a lot of us would, he said, ‘Hey, I think I can make something out of this.’”
Mullins opened a canister and showed it around to the audience.
“What do you see? What does it smell like? … What does it taste like?” he joked.
He explained that the power of black powder, or the gunpowder that he was holding, was eventually harnessed by the Chinese and turned into an effective tool of warfare — the first recorded grenades. Heating a little bit of black powder on a cast-iron fajita pan, the small amount immediately went up in flames at the touch of a torch, creating a dramatic cloud of smoke and drawing “oohs” from audience members young and old.
“What would happen if you took a bit of this solid, which turns into a rapidly-expanding volume of gas, a.k.a. ‘smoke,’ and put it inside a container where it couldn’t expand? That’s right, you’ve got hand grenades!”
Mullins explained that one day, one of the Chinese grenade workers was “having a bad day” and made the hole for the fuse too big.
“He put the fuse in there, and said, ‘Hmmmm. I don’t know if I trust our soldiers using this grenade. I’d better take it out to the field and test it myself,’” Mullins said. “So he lit the fuse, threw it out on the test range, and what do you think happened?”
Mullins confirmed what the audience was variously guessing at– the powder burned, the expanding gas tried to escape from the too-big fuse-hole, and the grenade went whistling in the opposite direction.
“What he’d discovered by sheer accident was the first rocket motor,” Mullins said. “He demonstrated Newton’s Third Law of Motion: Every action has an equal and opposite reaction. It’s a principle that wouldn’t be demonstrated for another 300 years.”
Mullins illustrated the basic principle by using a bit of the blackpowder to blow up a balloon that expanded and popped with a puff of smoke and a few harmless sparks. Then, he demonstrated the importance of having fins on a rocket to help guide its direction, similar to a boat with a rudder. Fins on rockets might help them propel with more accuracy in space, he pointed out, but what does one do when one has no “air” in space to provide friction for the rudder to move against?
“Around 1900, some brilliant American engineers discovered they could put one of these in their rockets and make their rocket go straight,” he said, holding a pair of bicycle wheels attached to an axle. “What do you think it is? Starts with a G … That’s right, a gyroscope!”
Mullins asked a young girl to have a seat on a tall swivel stool, her feet swinging, while she grasped either side of the axle on a bicycle-wheel gyroscope. Tilting the gyroscope from side to side, the girl giggled as she made a full revolution powered by the momentum of the contraption.
“The scientists figured out they could outfit their rocket with a gyroscope, align it with a point in space, and the gyroscope always maintained that relative position with that point in space,” Mullins said. “If the rocket got out of alignment, the gyroscope would tell the ground crew, who would bring the rocket back to position. When you get home tonight, take the garden hose and hold your finger over half of the nozzle, then the other half. Notice how it jerks your hand one way and the other. It’s the same principle.”
A couple more volunteers helped him depict the distance from the earth to the moon using kite string, a small beach ball and a tennis ball. “Keep going, keep going, WHOA!” he told the boy with the tennis ball “moon” and the loose end of the kite string. The boy made it to the other end of the large meeting room.
“That’s how far the moon is from the earth in scale distance,” Mullins said, “about 250,000 miles. It took us three days to get there, two days to get back when we went to the moon in 1969.”
Mullins asked who would like to go to Mars.
“It’ll take us 6-8 months to get there, we’ll have to live there for a year and two months until the planets line up properly, then it’s 6-8 months home,” he said. “You like to camp? Well, you know what food they’re considering to take to Mars with them, because they’re going to have to grow their own food … How about, crickets?”
A collective “ew” rose up from the audience. “They’re high in protein, they multiply quickly, they’re almost indestructible, and they have a delicate crunch when you eat them,” Mullins said.
But just as important as fuel for the body, will be fuel for the rockets, Mullins said. Oxygen and hydrogen will be needed to power a rocket strong enough to reach Mars.
In a final demonstration, Mullins pumped a giant water bottle full of hydrogen and oxygen, lit the end and everyone watched as the water bottle shot down the chute and landed with an almost instantaneous “thunk” against a foam cushion at the end of the chute.
“That was one ounce of rocket fuel,” Mullins said. “The rocket that took us to the moon burned 3.5 tons of fuel per second, per engine. There were five engines on the first stage. It produced 7.5 million pounds of thrust. The rocket weighed 6.5 million pounds, 363 feet tall, and 6 million pounds of it was fuel. It was so loud, it broke glass two miles away.
“In conclusion, ladies and gentlemen, this is not magic. This is rocket science.”
Mullins later put together an experiment in which the kids and their parents could create and decorate their own paper-tube rockets, setting them up with contraptions made out of what looked to be dowel rods, plywood and plastic accordion pumps. After enough paper-tube rockets filled the air, the group of about 20 were led down to the Space Museum next door for a film and a tour.
For more information about the Space Museum and Grissom Center, check out http://www.space-mo.org/ or call 573-358-1200.
Sarah Haas is the assistant editor for the Daily Journal. She can be reached at 573-518-3617 or at firstname.lastname@example.org