Man vs. the Machine
I am very disappointed by your conclusion that we need manned spacecraft going to Mars [“Time to Put a Foot Down,” Letter From Discover, April]. Do the arithmetic: It costs $400 million for a robot versus as much as $400 billion for a person. That means one manned flight could cost the equivalent of 1,000 robotic flights! We now lose two out of three robotic crafts due to accidents and engineering flaws. If you put a human on board, the luxury of losing two out of three crafts disappears. So does the luxury of mostly disregarding the near vacuum and the subzero working conditions and not having to transport life-support equipment. If you think that maneuvering a robot on Mars is difficult, don’t even think about manned flights to Mars. The complexity goes up by orders of magnitude, and your bang for the buck goes straight down the toilet. I once designed automatic flight-control systems for commercial aircraft. Ninety-nine percent of the engineering and testing went into keeping passengers alive and comfortable. That left 1 percent to fly the plane. The day will come when the technology exists to make manned flight to Mars economically viable. For now, just sit back and be patient.
JEFF KAHLER
Phoenix, Arizona
