“Shhhh,” Stuart said, trying to hold the squirming lizard against his body. The lizard jerked its head and began to shriek again. The sound bounced off the rocks and echoed in the stillness.
“Oh, dear,” Forbee-X said. “I’m afraid the birds heard the lizard!”
Artoo beeped frantically. Threepio watched in horror as the birds wheeled in formation and turned. The birds were heading straight for them!
Without a word, Stuart and the droids took off for the shelter of the boulders. Shadows fell over them as the birds flew lower, their giant wings beating rhythmically. The group scrambled over the rocks, looking for a crevice big enough to hide in. “Here!” Stuart called. He slithered into the crack.
Forbee-X’s arms shot out and extended even longer. She grasped Artoo in her strong fingers and deposited him in the crevice.
“Now you, Threepio!” she cried.
Threepio didn’t need any more encouragement. He hoisted himself down into the crack.
The bird flying at the top of the V formation suddenly swooped down, its claws extended.
“Forbee!” Threepio screamed.
Forbee-X’s legs extended, shooting her down into the hole. The frustrated bird wheeled, cawing angrily. “That was close,” Threepio breathed.
“It’s not over yet,” Forbee-X said worriedly. “Those beaks look awfully long. We need something to block that hole!”
Threepio screamed as the bird shoved its beak into the hole, missing him by millimeters. Forbee-X’s hand shot out and she slammed the beak hard. With a caw, the bird retreated.
“Stuart, Artoo, Threepio, look for smaller rocks,” Forbee-X directed. “Quickly!”
Threepio reached down for the biggest stone he could find. He handed it to Forbee-X. Stuart found a long, flat rock, which he handed to her. Forbee-X wedged the rocks into the opening, leaving just a tiny crack. She only hoped it would hold.
More birds arrived, cawing furiously. The lizard suddenly began to screech again.
“Stuart, hold the lizard’s mouth shut!” Threepio screamed.
“I can’t!” Stuart panted. “He keeps twisting away.”
The screeching bounced off the rocks and echoed, driving the birds into a frenzy. Threepio shrank back as he heard the scratch of their claws against the stones. The birds shrieked with fury as they tried to force their way into the opening. One bird shoved its slender beak into the crack between the stones. Forbee-X rapped the beak with a sharp stone. With an earsplitting cry, the bird angrily retreated.
But soon, the birds grew tired of their effort. One bird took off, wheeling in a circle around the others. After a few halfhearted pecks, the other birds followed.
“Whew,” Stuart said. “I thought we were bird food, for sure.” He peeked into the sling and petted the lizard gently. “Are you okay, little fellow?”
“Him? What about us?” Threepio shuddered.
Forbee-X yanked at the flat stone, trying to dislodge it. “I think I wedged this in a little too tightly.”
“Oh, dear,” Threepio moaned. “Now we’re buried alive! What could possibly happen next?”
“Maybe Artoo can help with a pincer claw.” Stuart suggested.
Artoo tried to jimmy the rock free with the thin edge of a driver. With a burst of effort, the rock flew out of the opening, almost hitting Threepio in the head.
“Artoo, really!” he exclaimed. “Maybe Forbee should give you another lesson in how friction works.”
Shakily, the group climbed out of the crevice. They scanned the sky above, which was empty. Artoo picked up the sled rope, and they continued on their journey.
The weather continued to warm as they walked. Forbee-X’s antennae kept rising and trembling as she took reading after reading.
“I just don’t understand this,” she murmured worriedly. “And I don’t like it, either.”
“What’s there to worry about?” Stuart asked cheerfully. “Traveling over grass is much easier than traveling over snow. We’re making good time.”
Artoo whistled a protest. He was having trouble dragging the sled.
“Let me help you, Artoo,” Stuart offered. He took hold of the rope and walked alongside Artoo. After a few minutes, he stopped and wiped his forehead. “Whew. This is hard work. Artoo made it look easy earlier.”
“That’s because he pulled the sled over snow, not grass,” Forbee-X said. “Remember when I described higher friction? It’s slowing the sled down more, making it harder to pull. You can always count on science to follow the rules!”
“That’s a great explanation, Forbee,” Stuart said grumpily. “But it doesn’t make it any easier to pull the sled. Why don’t we just leave it here? We could load the supplies into packs.”
“Good idea, Stuart,” Threepio agreed.
Artoo flashed his lights and beeped.
“Artoo has a point,” Forbee-X said. “The sled could come in handy later.”
“Well, of course you’ll side with him," Threepio grumbled.
Artoo chirped, then ended on a whistle that sounded awfully sarcastic to Threepio. Then he snatched up the rope to the sled and trundled away, dragging the sled behind him.
“Oh, dear,” Threepio fretted. “Now he’s gone off in a huff. Artoo can be so sensitive!”
Stuart ran ahead as Artoo disappeared around a bend. A moment later they heard a whoop.
“He did it! Artoo did it!” Stuart yelled.
“Did what?” Threepio muttered as Forbee-X zoomed ahead. “Why am I always the last to know?”
Threepio rounded the bend. Ahead, he saw Stuart, Forbee-X, and Artoo standing by a rushing blue river. Now Threepio could hear the sound of the water coursing over rocks and pebbles.
“Artoo heard the river!” Stuart shouted.
“But my auditory sensors are just as refined as his,” Threepio complained as he picked his way over the rocks at the river’s edge. “I didn’t hear a thing.”
“Maybe because you were jabbering so much, Threepio,” Stuart teased.
Artoo busily unloaded supplies from the sled. He placed them on the rocks nearby.
“So you’ve decided to leave the sled after all?” Threepio asked. “I’m glad you see it my way, Artoo. I always say —”
Artoo dragged the sled over to the river. He pushed it in, keeping careful hold on the rope. It bobbed in the shallow water.
“Excellent!” Forbee-X’s screen flashed a rainbow.
“It’s a boat!” Stuart cried. “What a hypergalactic idea, Artoo. Now we can really move!”
Threepio regarded the sled dubiously. “But will it hold all of us? May I point out that I am made of metal? I certainly don’t float.”
Forbee-X’s screen flashed a cheerful blue. “Density is the key to floating. It describes something’s weight compared to its size. Watch.”
“But the sled, I mean the boat, is metal,” Stuart said. “Metal is denser than water. So how could we possibly float?”
“Look inside the boat,” Forbee-X prompted. “What is it filled with?”
Together, Threepio and Stuart peered into the boat. “All I see are the supplies and some scrap metal Artoo salvaged from the pod,” Threepio said.
“What else do you see?” Forbee-X directed.
“Nothing,” Stuart said. “Just air.” Then his face brightened. “Oh, I get it! Air is less dense than water. But why wouldn’t the boat just sink while the air floated?”
Forbee-X’s screen beamed yellow. “In this case, the air inside the boat’s sides counts as part of the boat. Let’s use an example. Say you could take the boat, the scraps, and the air, and put them in a turboblender. Suppose the result was a perfect mixture of the three. If you took a cupful of that mixture, it would be less dense than a cupful of water. It would float.”
“But what if you added all of us to the blender?” Stuart asked.
“A cupful of the new mixture would be denser than before,” Forbee-X explained. “But it would still be less dense than water. So
—”
“We would float!” Stuart concluded.
“I’m not sure I like being put in a turbo-blender,” Threepio noted. “But I am glad to hear that I won’t sink.”
“So let’s get going!” Stuart said excitedly. He turned to Forbee-X and Artoo. “Sorry I ever doubted you guys. You were totally right about finding the river. I won’t argue with the two brains again!”
“Excuse me, Master Stuart,” Threepio said. “Aren’t you forgetting something?” He waited for Stuart to mention that Threepio had a helpful brain, too.
“Oh, right!” Stuart said. “I left the macrobinoculars on that rock!”
Threepio lowered himself into the boat in a huff. Nobody noticed his mood, which just proved how neglected he was. Artoo and Stuart followed. Forbee-X stood by, her screen slowly flashing from color to color. It meant she was pondering a problem.
Artoo beeped a question at her.
“No, I’m all right, Artoo,” Forbee-X said. “There’s something nagging at me, but I can’t quite place it.”
“Sorry, Forbee, but we don’t have time for you to figure it out,” Stuart said impatiently. “We’re burning daylight here.”
“Daylight can’t burn, Stuart,” Forbee-X explained. “Actually, it —”
“He means that we’re wasting time,” Threepio interrupted, afraid Forbee-X would launch into another lecture.
“That’s right,” Stuart said anxiously. “Now we only have thirty-five hours to make contact!”
Forbee-X stepped into the boat. “You see, the thing is —” she began, but her words ended in a very unscientific whoop as Stuart threw off the rope and the boat whirled away down the river.
“Weeee-oooooo!” Stuart yodeled.
“This is certainly an improvement on walking,” Threepio said, settling himself on one side of the boat.
At first, the boat sailed along smoothly. Then the craft picked up speed, causing Threepio to grip the side nervously. Spray hit their faces as the boat bounced along with the fast current.
“We’re speeding up!” Stuart called. The wind blew his dark hair away from his intent face. “This is great! We’ll make good time.”
“Oh, dear,” Forbee-X said.
“What?” Stuart asked.
“High water,” Forbee-X said. “It’s logical that the river would run high, considering how quickly everything thawed. I wish we’d stopped to make paddles.”
“But the current is carrying us so fast,” Threepio said. “Why would we need to paddle? It’s just wasted effort.”
“The paddles would help us steer,” Forbee-X explained.
“Steer around what?” Stuart asked. The boat got caught in an eddy, then popped free and whirled onward, faster than before.
“Rocks, for one thing,” Forbee-X said. “Because if we meet one at high speed, we could be in trouble. And what if we need to get to shore?”
“You worry too much, Forbee,” Stuart said. “And —” Suddenly, he stopped. “What’s that noise? Is it voices? It’s like a murmur.”
“That’s not conversation you’re hearing, Stuart,” Forbee-X said worriedly. “That’s what I’ve been trying to tell you. It’s rapids!”
The boat shot forward around a bend. Ahead they could see foaming white water. Rocks and boulders rose out of the churning water.
“Any scientific suggestions, Forbee?” Stuart yelled over the sound of the rapids.
“Yes,” Forbee-X answered. Her arms shot out and her fingers grasped each side of the boat. “Hang on!”
Suddenly, the bow plunged into the churning water. Artoo went flying, and Threepio grabbed him just in time. But it was hard to keep hold of Artoo and the boat at the same time. As the boat hit another rapid and flew into the air, Threepio shrieked. He’d lost his grip on the boat and Artoo! He saved himself from falling into the river just in time.
Forbee-X extended her legs and grabbed Artoo. She was able to intertwine her long steel toes to keep him secure.
The force of the water suddenly sent the boat skimming sideways, straight into a boulder. Threepio screamed as they smashed against it.
“We’re doomed!” Threepio cried.
With an awful scraping noise, the boat popped free and whirled on. Caught in an eddy, the boat swirled for an instant, then shot forward over a small waterfall. Threepio gasped as they hung in midair for a moment, then crashed down into the turbulent river. A wave of water hit them, almost swamping the boat.
“We’re going to drown!” Threepio yelled.
Forbee extended her arms. Metal expanded into webs between each finger creating makeshift paddles. She dipped her hands into the water, trying to steer the boat away from the biggest boulders as it pitched and bucked.
Through the mist ahead they could see another patch of turbulent water. Now Threepio was aware of a roaring noise.
“Waterfall!” Threepio cried, terrified.
“We have to get ashore!” Forbee-X yelled.
She dug into the surging water. The boat careened through the rapids, slamming against the water again and again. But Forbee-X managed to reach calmer water at the edge of the river. Stuart jumped out to pull them to shore.
They stepped out of the boat, relieved to be on land again.
“You really saved the day, Forbee,” Stuart said admiringly. He checked the lizard inside the sling — it looked okay, but nervous.
“What about me?” Threepio spoke up. “I helped, too.”
“You mean by screaming ‘we’re doomed’ every two seconds?” Stuart asked with a grin.
Artoo gave a long whistle.
“It isn’t funny, Artoo,” Threepio grumbled.
“I think you can all see that paddles are necessary if we want to complete our journey on the river,” Forbee-X pointed out.
Stuart scanned the ground around them. He picked up a fallen limb. “How about this, Forbee? Will this work?”
Forbee-X gripped the end of the limb and hefted it. “This will make an excellent shaft,” she told Stuart. “We’ll need something wider as a paddle blade.”
Artoo trundled off toward the makeshift boat. He reached in and brought out a thin sheet of scrap metal from one of the packs. It was oval-shaped, flat, and smooth. He showed it to Forbee-X.
“Perfect, Artoo,” Forbee-X approved. “We can use the macrofuser to shape it.”
Threepio felt left out again. He wasn’t terribly good at making things. He could make a good impression, of course. But paddles were another thing altogether.
He watched as Artoo macrofused the metal until it was a smooth, perfect oval. Stuart whittled the limbs into shafts. Then they fastened the metal blade to the shaft by using a small beamdrill and carbon screws.
Stuart held up the finished paddles. “Forbee, how do you use these things, anyway? I’ve never been in a boat without hydrosteering.”
“It’s very simple,” Forbee-X replied. “The Third Law of Motion says that for every push, there is an equal and opposite push. So you’ll push on the water ...”
“And the water will push back on the paddle?” Stuart asked doubtfully.
“Let’s get back in the river, and I’ll show you,” Forbee-X suggested. “But first, we need to bypass the waterfall.”
Threepio and Stuart carried the boat, and Forbee-X and Artoo carried the rest of the supplies. They slithered downhill past the roaring waterfall until they reached calmer water. Then they relaunched the boat.
Stuart and Threepio sat in the middle of the boat on opposite sides. Forbee-X handed each of them a paddle. Then she pushed the boat gently off the bank and stepped in.
Threepio dipped his paddle and pushed hard against the water while Stuart did the same. The boat swung in a circle.
“No, Threepio!” Forbee-X cried, clutching the sides of the boat. “You have to dip your paddle forward, then back! Not back, then forward. We’ll go in a circle forever.”
“But equal force sounds like a tug-of-war,” Stuart protested as he studied the
diagram. “It seems like neither the boat nor the water would move. Why does the boat move forward?”
Forbee-X’s screen cleared. “It is very much like a tug-of-war, only with pushes instead of pulls. Watch.”
“That’s easy,” Stuart said. “The other guy would win, no contest. There’s no way I could stand my ground with wheels under my feet.”
“Why not?” Forbee-X prompted.
Stuart frowned, thinking. “My opponent could keep a grip on the ground because of the friction between it and his feet,” he said. “Wheels reduce friction, right? So I’d get shoved away because of lower friction.”
“You are a born scientist, Stuart!” Forbee-X said, her screen glowing. “Compare that to the ‘pushing contest’ between you and the river water. Several forces help the water ‘stand its ground.’ Meanwhile, the friction between your boat and the water is low. As a result, you and your boat are easily pushed forward. Like this.”
Threepio and Stuart began paddling again. It took a few minutes to get themselves in synch. But soon they were moving swiftly down the river.
Suddenly, Stuart burst out laughing.
“What’s so funny?” Threepio asked. “I’m trying as hard as I can.”
“It’s the lizard,” Stuart explained. “He’s tickling me.” Carefully, he withdrew the squirming lizard from the sling around his neck.
The lizard turned its head to check out its surroundings. It blinked in a lazy sort of way, then crawled up Stuart’s arm and sat on his shoulder.
“Hey, little guy,” Stuart said, smiling. “Looks like you woke up.”
Artoo chirped and whirred.
“What was that, Artoo?” Forbee-X asked. “It’s going to storm?”
“He said it’s very warm,” Threepio corrected triumphantly. Forbee-X wasn’t perfect! “And look — there’s fruit on that tree now. When we landed, there were only leaves.”
Forbee-X’s screen went murky. “I’ve been trying to compute data since we landed. These climate changes are too sudden. They aren’t logical, yet they exist — a true puzzle for a scientist. But I think I’ve developed a theory about Planet X. I know it sounds incredible, but I believe this place experiences four seasons in one day. This morning, it was snowing. The trees were bare. Then, only hours later, the snow melted.”