Argument: Health-on-Risk-Not a good idea
Ask Marshall Brain: Why haven't we sent astronauts to Mars? The year 2004 is turning out to be a big one for Mars. Satellites are orbiting it, rovers are landing on it and the president is talking about it. So if Mars is so fascinating, why don't we put people in a spaceship and get them up there? After all, NASA was sending astronauts to the moon almost 35 years ago, with fairly limited technology by today's standards. Why is it so hard to get to Mars? Simply put, it's a long trip. Mars' orbit is about 140 million miles from the Sun, and Earth's is about 93 million miles. That means that even when the planets are at their closest point, they're still 50 million miles apart. That's 200 times the distance between Earth and the moon. If you launched a spaceship flying at 15,000 miles per hour, it would take at least five months to get to Mars (probably six or seven). And once you got there, the planets wouldn't be lined up nicely anymore. You would have to wait 18 months for them to get "close" again. Then it's another six-month trip home!
All of this would be extremely hard on the astronauts. The weightlessness would cause their bones to lose 1% of their mass per month. Then there's the radiation in space. The Earth's atmosphere and its magnetic field protect us from most of this radiation, but in space, astronauts are totally exposed.
And don't forget the psychological issues. Imagine being cooped up in something the size of an RV with the same five or six people for two or three years. The typical family would get pretty testy in just two or three days.
Another problem is the sheer size of the spaceship. It would have to carry more than 1,000 pounds of dehydrated food per person, plus tons of water and fuel, a big lander, life support systems, medical equipment and supplies, radiation shielding and so on. You can't launch a ship that big directly from Earth, because of gravity and atmospheric drag. The moon has one-sixth the gravity of Earth and no atmosphere, so we could build it there. Or maybe we could assemble it in orbit, using the International Space Station as a construction site.
It's definitely easier to keep sending robots to Mars instead of sending people. Robots don't need life support, and they never have to come home. But we won't send robots forever -- people will go to Mars eventually. It is like Mt. Everest -- we can't resist the challenge, so we will do what it takes to get there. But it may take a few more decades...