Learn the A-to-Z of Space Travel With NASA's Orion Spacecraft

Space is endlessly fascinating, but it can be difficult to know how to begin explaining its infinite vastness, especially to little ones. Enter the Orion A to Z—a colorful guide to space exploration put together by NASA.

The series combines concepts vital to the success of Orion, with bold, colorful illustrations and simple explanations. Here are the first three:

A is for Apogee: The term apogee refers to the point in an elliptical orbit when a spacecraft is farthest from the Earth. During Exploration Flight Test-1, Orion's flight path will take it to an apogee of 3,600 miles. Just how high is that? A commercial airliner flies about 8 miles above the Earth's surface, so Orion's flight is 450 times farther than that.

B is for Beyond Earth Orbit: When a spacecraft travels beyond Earth's orbit, it travels away from the planet, instead of circling around it. Orion is designed for deep space missions to go beyond Earth's orbit, like going to an asteroid or Mars. The crew module is powered by solar panels and batteries, allowing an unlimited power supply. Orion's life support system recycles water and oxygen for the crew, which allows them to travel through space for months. Orion's heat shield and crew cabin are also designed to shield the crew from the intense radiation encountered during deep space exploration.

C is for Crew Module: The crew module is a transportation capsule that provides a living area for the crew, and storage area for supplies and research instruments. Orion's crew module will carry astronauts on missions to destinations never before visited by humans and safely return them to Earth. The Exploration Flight Test-1 crew module will be the first Orion test vehicle sent into space.

But the best news? A downloadable poster and book will be "available once the entire alphabet is posted." That has to be the best present for any budding astronaut—or, let's face it, middle-aged nerd. [NASA]