How asteroid mining will save the Earth — and mint trillionaires

NOTE FOR 2019 READERS: This is the seventh in a series of digital time capsules for the next century. The series marks a little-known chronological milestone. According to UN data, life expectancy at birth in 27 countries now exceeds 81 years — which means babies born in 2019 are more likely than not to be alive in 2100.What will life be like at the other end of these kids' lives? The latest science, science fiction, and Silicon Valley all offer glimpses. But ultimately, it is our present-