It’s not an official name, but I think we can safely say that 2004 will qualify as Interplanetary Space Year. The new year is but a few days old, and already we have spectacular new images of a comet and the surface of Mars. Before the year is out, we will have much more from Mars, our first-ever orbiter of Saturn, and new telescopic views of how planets are born. At a time when the daily news is filled with reports of dangers — terrorists, rogue nuclear states, global warming, and even mad cows — planetary exploration reminds us that humans are also capable of great achievements.
Our Interplanetary Space year got underway on January 2, when the Stardust spacecraft passed within 150 miles of the surface of Comet Wild 2. From Earth, comets look like huge balls of gas and dust with long tails pointing away from the Sun. But all this material actually comes from a comet nucleus only a few miles across. Stardust penetrated through the gas and dust that enshrouds Wild 2 to snap pictures of the nucleus, and at the same time collected a bit of the comet’s dust. This dust is thought to be material from the earliest days of our solar system’s history, and scientists have long dreamed of being able to study it in the lab. Thanks to Stardust, that opportunity is fast approaching: Stardust is now on its way back to Earth, and about two years from now it will drop a capsule containing this first-ever sample of comet dust to a landing site in Utah.
Just a day after Stardust flew past its comet quarry, a robotic rover named Spirit touched down on the surface of Mars. It landed in the large crater Gusev, chosen as the landing site because views from orbit suggest it was once filled with liquid water. Spirit has already provided its first pictures of the crater floor, and over the next three months it will drive around to explore its surroundings and search for evidence that may help us understand whether Mars could ever have been home to life. Spirit’s success means that at minimum we have achieved the fourth successful Mars landing in human history. With luck, it will be followed to the Martian surface on January 24 by its twin, a rover named Opportunity. And British scientists have not yet given up hope of contacting the Beagle 2, which either landed or crashed on Mars on Christmas Day. If Opportunity lands and the Beagle 2 phones home, then in a span of a few weeks Earthlings will have landed as many successful spacecraft on Mars as in the previous four and a half billion years of our planet’s history.
While Spirit and Opportunity roam the surface, no less than three spacecraft will study Mars from above. The European Space Agency’s Mars Express, which carried the Beagle 2 to Mars, is right now maneuvering into its final orbit. By the end of this month, Mars Express will begin its scientific observations, joining the ongoing NASA missions Mars Global Surveyor and Mars Odyssey in mapping the red planet with unprecedented detail. Between all three orbiters, we should soon have much more definitive information about the history of water on Mars.
In the outer solar system, the action will be at Saturn. After seven years’ journey through space, the Cassini mission will enter orbit of the ringed planet this summer. We stand to learn more than ever about Saturn and its moons, but for most of us the best part may be a scientific by-product: as the solar system’s most photogenic planet, Saturn ought to yield some of the most beautiful photographs ever taken anywhere. Perhaps most exciting of all, in December Cassini will drop a probe named Huygens toward the thick atmosphere of Saturn’s moon Titan. Titan is so big that we would call it a planet if it were located in the inner solar system, but we have never seen its surface because it is perpetually obscured by clouds. When the European-built Huygens finally reaches the surface early next year, many scientists believe we will see spectacular vistas with lakes or oceans — but of liquid ethane and methane, rather than water.
We can also learn about our solar system by studying others, and a new space telescope should help us do just that during our Interplanetary Space Year. NASA’s Spitzer infrared telescope, launched just a few months ago, is now orbiting the Sun more than a million miles behind Earth. Because the disks of gas in which we believe that planets form are best viewed in infrared light, Spitzer should give us new insights into how our own solar system came to be. Combined with ongoing observations from the Hubble Space Telescope and many ground-based observatories, we should learn much more about our cosmic origins.
Last but not least, Interplanetary Space Year should see at least two more major launches of missions in our solar system: NASA’s Deep Impact and the European Space Agency’s Rosetta. Both are targeted at comets. Deep impact will crash into a nearby comet next year, while Rosetta will spend 10 years traveling to an eventual landing on a more distant comet.
Clearly, 2004 will be a year like no other in the history of human exploration. Never before has there been a year with so many “firsts,” and never before have so many new worlds been explored at once. In terms of sheer mileage, our space voyages this year are to the voyages of Columbus as his voyages were to a walk around the block. But perhaps the most important part of Interplanetary Space Year is its international character.
We often speak of these space missions as American or European, but in fact they involve scientists and engineers from virtually every country on Earth, and of every race and religion. Exploration is a human endeavor, and it belongs to no one person, nation, or culture. When we travel to other worlds, we show that conflict is not the only option open to our species. We can also cooperate, and in the process learn more about each other and about our remarkable but fragile Earth. For a total cost that is a tiny fraction of this year’s projected budget deficit, our space program offers the hope of a better future, one in which we all learn to work together to preserve our home planet, while at the same time taking our first steps off it into a future that may lead us to the stars.