When she was 10, a girl named Alice Bowman built a book of all the planets in the solar system and colored each planet with crayons. Jupiter was yellow and orange with a big red dot. Venus was green and blue. Saturn had a ring. On the ninth page, almost as an afterthought, Alice drew a lumpy gray circle and scrawled the words underneath: "mysterious gray rock."
The mysterious gray rock was Pluto. The year was 1970.
Thirty-six years later, on Jan.19, 2006, a spacecraft called New Horizons blasted off from the Cape Canaveral launch pad in Florida. As spacecrafts go, New Horizons was tiny — the size of a piano. But it was sitting on top of a rocket the size of a 22-story building. New Horizons flew faster at launch than any spacecraft before or since. It went supersonic — faster than the speed of sound — in 28 seconds. In nine hours, it crossed the orbit of the moon.
The spacecraft was flying to Alice's mysterious gray rock. And guess who was at the wheel?
All grown up now and a scientist, Alice was in charge of steering New Horizons as it flew through the solar system. Nobody was inside the spacecraft. Alice and her team were in a mission control center on Earth, where they used signals from a giant antenna to determine the spacecraft's position.
Alice was there as it flew beyond the rocky planet, Mars. She was there as it flew beyond the giant planets of Jupiter, Saturn, Uranus and Neptune. She was there when Jupiter's tremendous gravity flung the spacecraft even farther and faster into space.
She tracked it for nine whole years.
As it flew, it was decided that Pluto was too small to be a planet and would instead be called a dwarf planet.
As it flew, Barack Obama was elected president. The iPhone was invented and it flew, and the movie Frozen came out and it flew. The Earth circled the sun, and fall became winter became spring, nine times. And it flew and it flew and it flew.
And then, suddenly, 10 days before New Horizons was supposed to arrive at the mysterious gray rock, something went wrong. Instead of hearing a signal, Alice and her team heard nothing. They were no longer "locked up" to the spacecraft. In the mission operations center where they worked, lights on big screens switched from lively green to a gloomy gray.
"I can't believe this is happening," Alice thought.
For a moment, she panicked. Down the hall at the space center, someone started to cry. Then Alice and the engineers got to work. They worked fast. They made phone calls. They studied their computers. They checked the ground antennas.
Three billion miles away in space, New Horizons was all on its own. Where it flew, it was dark. It was empty. It was cold beyond imagination. It smelled like nothing. The sun was so far away that it provided no heat and only the faintest light. But up ahead lay Pluto.
They didn't know it at the time, but the spacecraft was so busy and excited getting ready to fly by Pluto that it got confused and slipped into "safe mode."
Suddenly, about an hour later, Alice and the team heard New Horizons asking for help. To their delight, they were "locked up" once again.
To tell a spacecraft what to do, engineers like Alice send commands that the spacecraft carries on its computer. A command looks like nonsense but contains important messages.
For example: PDU CD A HOLDOFF - ENABLE
These commands told New Horizons' cameras when to take pictures and what pictures to take. They told the cameras to look at the surface of Pluto and Pluto's moons. They told the computer to hold onto those pictures, and they told machines on the spacecraft to measure stuff around the planet. The commands for the Pluto flyby took up 750 pieces of paper.
Unfortunately, "safe mode" had erased all of these commands. And now, they all had to be resent — in just three days.
Alice's team worked like crazy, fixing the spacecraft and resending the messages. For days, they didn't sleep. Alice checked the commands line by line. And then she checked and checked again. She checked everything that could possibly go wrong.
Finally, on July 14, 2015, New Horizons did what the world had been waiting for. It flew by Pluto, snapping thousands and thousands of photos, and then it started beaming those photos back to Earth.
What Alice saw was extraordinary.
She saw steep, floating ice mountains that cut into the air like knives, mountains as big as the Rockies and canyons as deep as the Grand Canyon. She saw glaciers and volcanoes made of ice. She saw the shape of a smooth, giant heart stretching across the planet’s surface. She saw tiny, weirdly shaped moons. And she saw the biggest moon, Charon, looming above Pluto's horizon.
Pluto is an icy world — a land of many ices, she learned. The main ice is nitrogen ice, which is soft and gooey like toothpaste. Since Pluto’s temperature is close to nitrogen’s freezing temperature, the nitrogen ice is freezing and melting all the time — just like water ice on Earth. Nitrogen streams are flowing down the mountains, melting into valleys, cracking mountains into glaciers.
Pluto wasn't a mysterious rock anymore. Pluto was alive. And it was the most beautiful thing Alice had ever seen.