Karen Romano Young 
Space Junk [PDF ebook] 
The Dangers of Polluting Earth’s Orbit

Scientists have identified at least 100 million pieces of space debris-from paint chips to nonoperational zombie satellites-floating in Earth’s orbit. And over 100 tons of those pieces enter Earth’s atmosphere each year! Journey into outer space and learn about the dangers of space junk collisions, how scientists track them, and how space agencies are working to develop new technologies to clean up the space junk. Along the way, you’ll hear from the scientists who are working to ensure that outer space remains a safe place to travel and explore. If we don’t tackle the space junk problem, it might be impossible to travel into space; it could even trap us on Earth.