By David Chandler

The idea that Mars, like the earth, might be the home of living beings has held our imagination since the turn of the century, when Percival Lowell thought he saw hundreds of canals crisscrossing the face of the planet, and took them as proof that Mars was inhabited.

Lowell was wrong. The canals never existed, as Mariner 9 photographs finally proved five years ago. But even though his evidence was mistaken, Lowell's conclusion may yet be vindicated: the Viking landers have returned an impressive array of biochemical data which seems to show that some form of life really does exist on Mars.

The results of the Viking life-detection experiments have been more positive than most people expected. Dr. Robert Jastrow, director of NASA's Goddard Institute for Space Studies, says, "Short of seeing something wiggling on the end of a pin, the case for life on Mars is now as complete as the Viking experiments could make it."

But no one wants to make predictions about Martian life which might be proved wrong by later evidence; scientific reputations could too easily be damaged in the process. So the Viking scientists have been extremely cautious in interpreting the results of their biology experiments. And the official NASA position straddles the fence. As Viking scientist Dr. Carl Sagan of Cornell University puts it, "We have clues up to the eyebrows, but no conclusive explanations of what we're seeing."

The idea that Mars, like the earth, might be the home of living beings has held our imagination since the turn of the century, when Percival Lowell thought he saw hundreds of canals crisscrossing the face of the planet, and took them as proof that Mars was inhabited.

Lowell was wrong. The canals never existed, as Mariner 9 photographs finally proved five years ago. But even though his evidence was mistaken, Lowell's conclusion may yet be vindicated: the Viking landers have returned an impressive array of biochemical data which seems to show that some form of life really does exist on Mars.

The results of the Viking life-detection experiments have been more positive than most people expected. Dr. Robert Jastrow, director of NASA's Goddard Institute for Space Studies, says, "Short of seeing something wiggling on the end of a pin, the case for life on Mars is now as complete as the Viking experiments could make it."

But no one wants to make predictions about Martian life which might be proved wrong by later evidence; scientific reputations could too easily be damaged in the process. So the Viking scientists have been extremely cautious in interpreting the results of their biology experiments. And the official NASA position straddles the fence. As Viking scientist Dr. Carl Sagan of Cornell University puts it, "We have clues up to the eyebrows, but no conclusive explanations of what we're seeing."The idea that Mars, like the earth, might be the home of living beings has held our imagination since the turn of the century, when Percival Lowell thought he saw hundreds of canals crisscrossing the face of the planet, and took them as proof that Mars was inhabited.

Lowell was wrong. The canals never existed, as Mariner 9 photographs finally proved five years ago. But even though his evidence was mistaken, Lowell's conclusion may yet be vindicated: the Viking landers have returned an impressive array of biochemical data which seems to show that some form of life really does exist on Mars.

The results of the Viking life-detection experiments have been more positive than most people expected. Dr. Robert Jastrow, director of NASA's Goddard Institute for Space Studies, says, "Short of seeing something wiggling on the end of a pin, the case for life on Mars is now as complete as the Viking experiments could make it."

But no one wants to make predictions about Martian life which might be proved wrong by later evidence; scientific reputations could too easily be damaged in the process. So the Viking scientists have been extremely cautious in interpreting the results of their biology experiments. And the official NASA position straddles the fence. As Viking scientist Dr. Carl Sagan of Cornell University puts it, "We have clues up to the eyebrows, but no conclusive explanations of what we're seeing."The idea that Mars, like the earth, might be the home of living beings has held our imagination since the turn of the century, when Percival Lowell thought he saw hundreds of canals crisscrossing the face of the planet, and took them as proof that Mars was inhabited.

Lowell was wrong. The canals never existed, as Mariner 9 photographs finally proved five years ago. But even though his evidence was mistaken, Lowell's conclusion may yet be vindicated: the Viking landers have returned an impressive array of biochemical data which seems to show that some form of life really does exist on Mars.

The results of the Viking life-detection experiments have been more positive than most people expected. Dr. Robert Jastrow, director of NASA's Goddard Institute for Space Studies, says, "Short of seeing something wiggling on the end of a pin, the case for life on Mars is now as complete as the Viking experiments could make it."

But no one wants to make predictions about Martian life which might be proved wrong by later evidence; scientific reputations could too easily be damaged in the process. So the Viking scientists have been extremely cautious in interpreting the results of their biology experiments. And the official NASA position straddles the fence. As Viking scientist Dr. Carl Sagan of Cornell University puts it, "We have clues up to the eyebrows, but no conclusive explanations of what we're seeing."