DANIEL S. GOLDIN has thrown down what he calls "a special challenge."
The administrator of the National Aeronautics and Space Administration (NASA) told the recent World Space Congress: "I believe we can build a spacecraft in three years weighing hundreds, not thousands of pounds, and costing a few hundred million dollars, not billions - and have it arrive at Pluto, the last unexplored planet, in the first years of the 21st century."
Spacecraft designers and mission planners will have to meet another Goldin challenge to do it. Because he doubts space agency budgets will grow significantly, he said: "[We] space professionals ... must revolutionize the culture of our organizations to carve money for new projects out of existing budgets. We must ... make ourselves build spacecraft smaller, faster, and cheaper."
These challenges encapsulate the essence of what Goldin calls the "new age of exploration" in space. It is an age of enormous scientific opportunity and stringent national budgets.
It now is possible to explore the entire planetary system, including distant Pluto. It is possible to get to know Mars and our moon in intimate detail. It is possible to use that knowledge, along with space-based monitoring of Earth, to learn what we are doing to our own planet. But,"no nation can do it alone," Goldin noted. They have to "coordinate [their] efforts and resources," he said.
German astronaut Ernest W. Messerschmid of the University of Stuttgart made a similar point in connection with human expeditions to the moon and Mars. "I think the theme of going to Mars should not just be `to Mars together' but `to Mars with new technology,' " he said. He added that, with the end of the cold war, the facilities of the whole world are available to develop ways to "get into space more cheaply."
In a paper presented at the space congress, the NASA team looking into possible Pluto missions said it is aware that "cost has replaced performance at the top of the list of guiding principles in project development." That means holding Pluto mission costs to around $400 million. This could be done using spacecraft of a few hundred kilograms mass that could be launched on trajectories that would take them to Pluto in around 7 to 11 years. One option the team is evaluating is possible use of a Russian Pro ton rocket to launch the probe.
Planetary scientists have wanted a close look at Pluto for a long time. Its distance makes this difficult. Up to now, no nation has been willing to fund such a mission.
Pluto takes 248 years to orbit the Sun. During that time, its distance from the Sun ranges from 30 times to 50 times the average radius of Earth's nearly circular orbit. Pluto is relatively close at hand right now. It passed through its orbit's perihelion - the point closest to the Sun - in 1989.
The NASA study team says its work shows that "Pluto is now clearly within reach." Furthermore, this is a unique opportunity to study the planet. The gradual dimming of starlight - rather than a sharp cutoff - when Pluto passed in front of a star in 1988, showed that the planet currently has a thin atmosphere. Atmospheric analysis would be a priority objective of any fly-by mission.
The study team notes, however, that this atmosphere is beginning to condense as Pluto moves away from the Sun. It warns that "it is essential that Pluto be explored before the 2020s when its atmosphere will be frozen onto its surface for the next two centuries."
Astronomers know very little about Pluto and its only known moon, Charon.
With a diameter 18 percent that of Earth and only 0.2 percent of Earth's mass, the planet is a midget. Charon is another anomaly. It is half as big as Pluto with 20 percent of the planet's mass. That makes Charon the largest moon in relation to its planet in the solar system.
Pluto's orbit also marks the planet as an oddball. It is much more elliptical than the nearly circular orbits of the other planets. And it is inclined 17 degrees to the ecliptic plane - the plane of Earth's orbit.
Studies of the system's mass suggest that Pluto has a lot of rocky material in its makeup. Observing the planet by infrared "light" last May, Tobias Owen and colleagues at the University of Hawaii detected nitrogen ice on its surface. They also confirmed the presence of methane ice, which had been detected before. This suggests the atmosphere consists largely of nitrogen with some methane.
Reviewing the few facts known about Pluto in Astronomy magazine last month, planetary scientist Alan Stern of the Southwest Research Institute in San Antonio, Texas, observed that "it is difficult to explain how this single little world developed at the ragged outer edge of the planetary system."
On-site data from even a small spacecraft, therefore, would probably be a revelation. "There is no doubt that important pieces to the puzzle of our own Solar System's formation will be revealed with a successful initial reconnaissance," the NASA study team said.
For NASA administrator Goldin, the fact that such a mission now is technically feasible and financially reasonable symbolizes how fast the capacity for space exploration is developing. Also, he says the fact that some of the most important exploration possibilities require international partnership could help better human relations here on Earth.
"The international cooperation necessary to explore the Earth [from space], explore the moon, and send humans to Mars, I believe, can inspire the entire planet to see what can be accomplished if we replace our habit of confrontation with cooperation," he said. It was a theme that echoed throughout the space congress.