A question a practical engineer is required to ask: "How much is a human life worth?" The typical shrill emotive response is: "Human life is priceless! You can not put a dollar value on a person's life." If one has the patience and the audience has sufficient intelligence, the issue of term life insurance is at this point brought up. Most of us put a value on our lives when we get term life insurance. I'm insured for about $300,000. At one point during his career, my father was insured for $1,000,000 (he was probably paying too much for insurance). My father is now retired and currently has no life insurance at all. Whenever you get into an automobile, you assign a value to your life. How many of you drive around in Volvos (one of the world's safest cars)? When he still worked, my father commuted in a Volvo. I attach a high value to my family's safety but can't afford a Volvo, so the family rides in a Saturn. When I'm by myself, I like to drive my 1968 Karman Ghia (one of the world's coolest but most dangerous cars). Obviously I assign a much greater value to my family's safety than my own.

This is preamble to the problem of assigning a dollar value to a human life. The value one typically sees is somewhere between $100,000 to $1 million for a human life. The Space Shuttle operates under a launch to orbit cost of $10,000/kg. The Shuttle was originally designed to fly one hundred times before being sent to the museum (this number is almost certainly optimistic and should be reduced to 50). Assume the Shuttle has an average crew size of 5 people. Assume the value of an astronaut's life is $1 million dollars. How much mass can be economically justified for an escape system on the Space Shuttle?

Answer: 10 kilograms

You can not build an escape system that weighs only 10 kilograms. This is why the Space Shuttle has no escape system (the Columbia originally had ejection seats for 2 astronauts but that system was removed after 5 flights for reasons of economy).

Why was there an escape system on the Apollo command module? Answer: It was a single use vehicle. The above mathematics for the Saturn-V yields an allowed escape system mass to be 300 kg. The command module escape tower weighed a bit more than that. However the Apollo program was about National Prestige so it was worth spending a little bit more on an escape system.

Gary