Sky & Telescope July 2003 [antikvár]

Silent(ly) RunningJay White ponders the lonely isolation of a spacecraft bound for the stars.It's been more than 30 years since that night when the lights in the theater came up and tears filled my eyes. The film Silent Running, just ended, should have affected me because it showed Earth's last forests thrust into the dark oblivion of space. But I was only 10 years old, and the real source of my despair was a robot named Dewey. Short and stubby and built like a tool box with thick, chicken legs, Dewey was left alone in a domed space vessel filled with trees, streams, and small varmints the legacy of an Earth overrun by concrete and pollution.As a child I thought mostly of Dewey all alone out there, waddling among the plants with a battered watering can. Three decades later, as an adult, I am thinking of a real caretaker of a human legacy: a collection of metal and silicon named Pioneer 10. Launched in 1972, about the same time as Hollywood Dewey, this robotic explorer rushes deeper into outer space every moment, carrying a greeting from humans and charged with an electronic imperative to explore.Pioneer 10 has no plants to tend; its job was to inspect grand Jupiter at close range. As it approached that mighty world of ochres and umbers and its persistent Red Spot in December 1973, we collectively gasped at the crude but colorful views of fluid, swirling mists and a seemingly bottomless atmosphere a place nothing like our own of rock, seas, and puny vapors. And this durable emissary from Earth just kept on going, surpassing Pluto's distance from the Sun in 1983. By then 11 years into its flight, the swift-moving craft had departed the solar system's family of planets. "Ladies and gentlemen, Pioneer 10 has left the building."In March 2002 NASA scientists sent a message to their far-flung probe, trying to reach out and touch it even as momentum was carrying it in the general direction of Taurus. Pioneer replied 22 hours later, not because it needed time to consider a response but because that's how long light takes to make the round trip over a distance of 11.9 billion kilometers. Being only 11 light-hours away after a speedy voyage of 30 years gives one an appreciation for the true extent of a light-year, which in the cosmic scheme is itself quite tiny.Imagine yourself Pioneer 10, immersed in the unpunctuated dark, cold emptiness that is interstellar space no planets to approach, no stars swishing by, and only the occasional atomor dust grain to encounter as you glide silently along. All you've got to look forward to is a distant encounter with the great star Aldebaran, marking one of the eyes of the bull Taurus, in 2 million years.Attached to the side of Pioneer 10 is a plaque, designed by astronomers Frank Drake and Carl Sagan, that depicts a man and woman posed in greeting and "landmarks" of our interstellar neighborhood. As children we cast into seas bottles filled with scribbled messages; Pioneer 10 is an interstellar bottle that now carries the message of our adolescent species a plaque announcing through the light-years and the ages, "We're here. Where are you?"Before it left the planetary realm, Pioneer was pitted and popped by interplanetary debris. Interstellar space, however, is believed to be much emptier, so the spacecraft has already suffered the most severe pelting it will likely encounter. This has interesting implications for our mechanical ambassador's message. It is possible that the kindly image of man and woman zipping right now through the darkness will appear much the same for hundreds of millions of years, their two-dimensional outlines conveying a howdy to anyone who sees them. Indeed, long after humans stop remembering that they built a spacecraft named Pioneer 10, it will still be carrying an image of us as we now are. There is even the possibility that the craft will bear silent witness to the giant evolution and ultimate demise of the parent star of,its home world.Last January 23rd NASA scientists received the final, feeble message from Pioneer 10. With too little electrical power left to raise its radio voice beyond a whisper and respond to our queries, the spacecraft hurtles outward, never more to speak with us. Cinematic Dewey was left alone to tend to its plants and carry memories of its human creators into the great unknown. Similarly, Pioneer 10 bears our legacy to the stars. It will take a great while to reach them, but this little spaceshipnow has nothing but time and a mission to continue_outthere, silently running forever.James C. White II, formerly executive director of the Astronomical Society of the Pacific, is the Lester Crain Professor of Physics and chair of the department of physics at Rhodes College in Memphis, Tennessee.