1A century ago, rockets were dangerous novelties, but today private companies launch them into orbit almost every week.
2Reusable boosters now return to Earth and land upright, which has cut the cost of reaching space dramatically.
3Some firms sell short trips to the edge of space, where passengers experience a few minutes of weightlessness.
4Engineers are also designing giant ships meant to carry the first settlers all the way to Mars.
5The journey would last several months, and the crew would face radiation, isolation, and constant danger.
6On arrival, the settlers would need to produce their own air, water, and food from local materials.
7Ice buried under the Martian soil could be melted and purified to supply a small colony.
8Storms of fine red dust sometimes cover the whole planet and block the sunlight for weeks.
9Critics argue that the money spent on Mars could solve urgent problems here on Earth instead.
10Supporters answer that becoming a species of two planets would protect humanity from a single catastrophe.
11Whether the first Martian child is born in fifty years or two hundred, the attempt has already begun.