Galileo's End


(This column was first published in the September 15, 2003 issue of The Buffalo News.)


The National Aeronautics and Space Administration (NASA) has been taking its lumps lately. The loss of life on the Challenger and Columbia spacecraft have dealt the agency stunning blows and the failure of two successive unmanned Mars probes have added to its ill fortune.


Those catastrophes should not be underestimated, but we should not let them erase NASA's many remarkable achievements. Our astronauts have visited the moon; our small land rovers have wandered the surface of Mars; our Apollo 13 astronauts were brought back safely after an explosion severely injured their craft; our Pioneer vehicles have given us extensive new information about our outer Solar System; and our astronauts live for months in a space station circling Earth.


These activities represent the modern equivalent of the explorations of Ericson, Columbus, Hudson, Magellan, Cook, and Lewis and Clark.


Now the Galileo Orbiter's eight-year tour of the moons of Jupiter and its fourteen-year life in space are coming to an end. On September 21 it will carry out the program sent to it from Earth telling it to destroy itself in the terrifying heat of Jupiter's atmosphere.


Michael Benson has ably told this spaceship's story in the September 8 New Yorker. I will draw upon his account to provide some insights into the extreme difficulties encountered by our space agency and its remarkable ability to respond to those problems.


First planned and built thirty years ago - back when the first electronic hand-held calculators were just replacing slide rules - Galileo's instrumentation was already dated when it was delivered into space in 1989. For example, one of its main processors was a rebuilt chip whose normal use had been in the video game Pong.


Its booster was so severely underpowered that NASA managers had to come up with a creative way to get the tiny vehicle to Jupiter. Their remarkable solution: Galileo built up speed by going first around Venus, then back to circle Earth twice, before it finally slingshot out to the more distant planet.


But then that old equipment, so severely stressed by its frigid and radiation-stressed environment, began to develop problems. Its high-gain antenna wouldn't erect and messages had to come from a smaller one, slowing communication almost to a halt. But even that problem was partially solved by creative reprogramming of the spaceship's software by NASA scientists.


Among the results: spectacular pictures of volcanic fires on Jupiter's moon Io and deep fissures in the icy crust of its other moon Europa. That second observation has led to speculation that Europa's global ocean may contain more water than all of our own planet. One NASA scientist noted that the discovery of this ocean is next in line after Balboa's initial observation of the Pacific in 1513.


That Europan ocean may even harbor life and that is why Galileo must be destroyed. The spaceship's power is waning and, continuing on uncontrolled, it might crash into that moon, bringing to it alien microorganisms from Earth. The prospect of wiping out fragile life forms that may survive deep under that icecap has led to this decision.


From Benson's description of its final moments: "Galileo will be traveling at a speed of thirty miles per second, and its boxy octagonal frame will start glowing red. Seconds later it will be white-hot.... By the time the spacecraft's remains are 300 miles inside Jupiter's atmosphere, where the temperature is 1200 degrees, all its aluminum components will have vaporized. At 600 miles, its titanium parts will disintegrate.... Having just crossed Jupiter's threshold, it will vanish, leaving no clues of its earthly origin or its complicated mission."-- Gerry Rising