Experience tells us that space explorers have several key attributes in common, regardless of whether their objective is our planet or a distant one, regardless of whether their method is robotic or piloted. They need to have vision, great curiosity, and a strong sense that some information and understanding essential to resolving problems on Earth lies beyond our current grasp. They often need tremendous patience to stick out long campaigns despite political, financial, or technical delays. To prepare themselves for their tasks, they will need great self-discipline; to succeed at them they will need, in addition, courage, ingenuity, and the occasional stroke of luck.

We are well past the era when frontiers were challenged by single families embarking in covered wagons or by small groups of men setting off in sailing vessels. Nowadays our expeditions require large interdisciplinary teams of people who can master not only complex technology but also the trickier challenges of finance, politics, and human relationships.

The Grand Canyon of the Colorado River [STS034-72-056] The Grand Canyon of the Colorado River dwarfs its human habitation in the national park on the south rim (in the very center of the photo, pointed to by the road from the south and an airfield parallel to the road on the right). The immensity of this great canyon amazes the modern visitor just as it amazed early explorers of the American West. Owing to the uplift of the 6500-foot Colorado Plateau, the Colorado River excavated the mile-deep canyon in less than 4 million years, a small fraction of geologic time. The STS-34 astronauts used their new vantage point on this old wonder to take overlapping photographs that allow stereoscopic reconstruction of the entire length of the Grand Canyon (stereo series is frames 052 through 057).

The Tongue of the Ocean [STS029-90-012] One of the things Shuttle photographs reveal to us about the ocean is its variations in depth. Especially striking is the contrast seen here between the limestone banks from which the Bahamas protrude and the precipitous drop into the channel called "The Tongue of the Ocean." The water around Andros Island, just to the left of the deep-blue "tongue," is only about 3 meters deep, whereas the bottom of the channel is over 1000 meters deep. Notice the patterns made in the sand of the shallow bank as the ocean water funnels into the deep.

Some of these teams will set their sights outward, pressing on to explore and perhaps eventually settle other worlds in our solar system. Others - myself among them - will remain committed to exploring and understanding our current home, using the vantage point of space to find better answers to our many questions about its past and its future.

A Clean World and a Dirty One [STS030-77-059 & STS043-22-009] Venus shines clearly through the atmosphere above the Earth's horizon in this photo taken in May of 1989. But a haze of smoke, smog, dust, and - the biggest contributor - ash and aerosols from the eruption of Mt. Pinatubo in the Philippines obscures the astronauts' August 1991 view of the Earth's limb.

Both of these quests clearly exceed a single lifetime. That means that many of the key team members for the future are in the classrooms of the world today. Will their education prepare them? Will they care enough to join in these great explorations? Will they have the curiosity, knowledge, and self-discipline required to succeed? I certainly hope so, because the world will certainly need them.

A potential astronaut practices docking a Manned Maneuvering Unit with a satellite in the "Training Program" at the Kansas Cosmosphere & Space Center in Hutchinson, Kansas.

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