A Robot on Mars Finds the Oldest Bedtime Story

Professor Pip stood on top of a rocky hill just as the sun was thinking about going down. He held his round brass magnifying glass in one paw and, from another pocket, produced a small striped rock about the size of a mango. Layers of tan, brown, ochre, and dusty red ran across it in stripes.

"Ah! My favorite kind of storyteller," he said, holding the rock up to the sky.

Mia and Leo tumbled up the hill behind him.

"That's just a rock," Leo said, out of breath.

"A rock, yes," said Pip. "But this rock is a book. Every stripe is a page. And every page is a day, or a season, or a whole long-ago afternoon."

He set the rock on a flat boulder. Then he reached into a pocket, pulled out a shallow tray of flour, and set it beside the rock. From another pocket came three marbles.

"Now watch." Plop! He dropped a marble into the flour. It left a little crater. Plop! Plop! Two more marbles, two more craters. Puffs of white flour drifted up.

Mia clapped. "Meteor rain!"

"Precisely," said Pip. "And this — THIS — is what happened to Mars and to our own Moon a very, very long time ago. The sky rained rocks. Big rocks, small rocks, comets, asteroids, everything. That time is called the Late Heavy Bombardment. It happened almost 4 billion years ago."

Leo tried to whistle at the number and failed. "That's SO much older than Grandma."

"That is older than Earth's oldest mountain," Pip agreed. "And here is the amazing part. A very brave robot named Perseverance — a rolling car-sized geologist that NASA sent to Mars — has been driving around the edge of a giant crater called Jezero. Just a few days ago, scientists announced that Perseverance found a huge stack of layered rock, seventy-five metres tall, that was made during that very rain of comets, almost four billion years ago."

He pointed his magnifying glass at his little striped rock. "Every time a big rock smashed into Mars, it shattered the ground into a thousand little chunks. Then the heat of the crash melted some of them and glued them back together into a new rock. That crashed-and-glued kind of rock has a name too. It's called an impact breccia. Say it with me: brech-EE-ah."

"Brech-EE-ah!" the children shouted.

"Oh!" said Mia, "That's like a Rice Krispie treat. Lots of little pieces stuck together into one big thing!"

"Exactly right!" cried Pip, clapping his little paws so hard his spectacles slipped down his nose. "A Rice Krispie treat made of crashed meteor and molten stone. Perfect."

He turned toward the horizon, where a small reddish dot was climbing up out of the pink sunset sky. "That, my friends, is Mars, glowing in our own evening. And right now, Perseverance is rolling along its dusty hills, reading those pages. Every rock is a page. Every page is a story of a day."

He gave each child a small pebble. "Tonight, when you find Mars in the sky, tell it hello from us. And whisper: 'I know some of your oldest stories now.'"