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Projects: Observing Earth

Earth Is, After All, A Planet

by Charles F. Kennel and Louis D. Friedman
From the July/August 2008 issue of The Planetary Report.

Earthrise over the lunar horizon
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Earthrise over the lunar horizon
This view of Earth rising over the lunar horizon is one of the most famous images of the twentieth century, captured in December 1968 by the Apollo 8 crew during the first manned trip behind the far side of the Moon. It showed us Earth, as it appears floating in space, for the first time. Credit: NASA

Our planet is changing. Although public debates over why things happen and what to do about them may never be settled, the scientific community has reached that magical state called consensus with the latest report from the Intergovernmental Panel on Climate Change (IPCC). Amazingly, a group of contentious, jargon-talking researchers managed to write a cohesive document, one that earned them, along with Al Gore, the Nobel Peace Prize for 2007.

The IPCC never could have reached that point without the data collected by generations of orbiting spacecraft dedicated to studying Earth. Global rainfall patterns, sea surface height, atmospheric structure—these are the sorts of measurements we need to understand the large-scale processes that control Earth’s climate.

Orbiting instrument platforms are not the sole sources of these important data. Space exploration changed forever the way we humans see our home world. Apollo 8 astronauts brought us the iconic image that showed us Earth as it truly is—blue and inviting in the black immensity of space. This image jump-started the environmental movement.

It is ironic, then, that just as NASA’s satellites are making new discoveries about the state of our planet, in February 2006, the United States’ space agency chose to drop the phrase “to understand and protect the Earth” from its mission statement. We won’t speculate on the reasons. It’s enough for us to say that The Planetary Society was prepared to pick up the phrase and the mission.

The View From Space
Last year, the Society added Earth to its mission statement, which now reads, “To inspire the people of Earth to explore new worlds, understand our own, and search for life elsewhere.” We are now developing programs to initiate that new mission. This special issue of The Planetary Report is a step toward fulfilling our updated commitment.

With a change in wording that may seem small, The Planetary Society was not merely making a political statement; it was codifying a large and important goal. Understanding the planet we live on has always been an implicit part of the enterprise of planetary exploration that we so ardently advocate. We have just made it explicit. We have broadened our mission statement to encompass one of the most important benefits of space exploration: providing a context among other worlds and a vantage point in space from which we can look back on our home world.

What NASA once called a Mission to Planet Earth is critical now, as human actions change our planet in ways that are not beneficial to our species—or to others. Knowing this intellectually is one thing; moving from knowledge to action is another.

Coping with change is hard, and mitigating the effects of change is even harder. Stopping global climate change probably is impossible, but an informed humanity probably can slow it down and cope better with its effects. It is critical that we understand the processes.

No nation can tackle this on its own. The spacefaring nations in particular must work together to address global change.

The sheer complexity of Earth’s weather and climate makes it difficult to tease out the trends of change. Standing on the surface, it’s hard to get the kind of data needed to fill in details of the big picture. When you’re talking about global change, you need to step back until you reach a global perspective. That perspective can be found only in space.

Getting to Know Our Neighbors
Space exploration has triggered another change in perspective. Earth’s sister planets were once only wandering lights in the night sky. As our robotic pathfinders reached them, however, they became idiosyncratic worlds of amazing diversity and beauty. From information gathered at such diverse worlds as banded Jupiter, large enough to swallow 1,000 Earths, to the seemingly insignificant rocky asteroids measured in meters, we’ve come to know that our world is just one among many unique individuals in this solar system—but it is the one with life on it.

In our planet’s history, our solar system neighbors have had a profound effect. Consider one of the greatest mysteries of science: what happened to the dinosaurs? The leading suspect is now an invader from space, an asteroid. Although scientists still debate if an asteroid impact alone was enough to wipe out the dinosaurs, there is consensus that an object from space struck near the Yucatan Peninsula 65 million years ago and changed Earth’s climate in ways that made it impossible for dinosaurs, and many other life-forms, to survive.

Critics of space programs around the world are badly off target when they claim it is a waste of good money to study other worlds when there’s so much trouble on this one. Even bigger trouble can come from space—as the dinosaurs learned the hard way. Trouble on this planet sometimes is visible only from space. We need to maintain that perspective.

About the Authors
Charlie is working with The Planetary Society because of his respect for its effectiveness, its success in rallying public support for space exploration, and the way it brings science and scientists to the public. He is a leader in Earth observations from space and a respected scientist who served as associate administrator for Mission to Planet Earth at NASA headquarters.

Lou is executive director of The Planetary Society and is honored to have Charlie working with us.