Four decades after Apollo 11 landed on the moon, we seek clean energy sources, a healthy environment, and a peaceful world. To achieve these goals we must implement new approaches. "Business as usual" is no longer acceptable. Energy and resources are limited on the Earth and acquiring them adversely impacts the environment. In space, however, they are present in abundance and can be acquired without damaging ecosystems.

By including space activities in our efforts toward these goals, we can attain benefits that other answers alone cannot provide, while protecting the Earth's environment. In this way we can achieve a secure, sustainable future—with abundant energy, resources, and opportunities for all to have more fulfilling lives.

We will soon have the ability to utilize the opportunities of space; what we need is a clear vision of what could be achieved and the determination to reach for the vision. Crossing the Threshold: Advancing into Space to Benefit the Earth shows how we can do that.

Excerpt from the Preface:

Arriving home from work one Thursday in mid-January 2000, I found a phone message—from the White House. A staffer had called on behalf of President Bill Clinton, who was asking leading authorities to describe the futures of their fields. The responses were to be compiled into a book for the president: Visions of the Future from Leading Thinkers. A "one- to two-page memo directly to the president" was requested on how I see space activities "coming along in the next 50 to 100 years or even further." Honored and excited, I composed my thoughts and sent the memo by the requested date, the following Monday.

Such a request from the president is not to be refused, but discussing a 50- to 100-year period is a formidable task and I was not satisfied with the result of my effort. Three days were simply insufficient time to do justice to the topic, and two pages to describe our future in space provided too little, well—space—to do so properly. Only in a book could I adequately respond. This is that book.