Most technological advances are actually just improvements. One thing builds on the next: from shoddy to serviceable, from helpful to amazing. First you had a carriage, then a car, and then an airplane; now you have a jet. You improve on what is there. Technological advances are like that.
Except for the one that involved landing on the Moon. When a human went and stood on the Moon and looked back at the Earth, that was a different kind of breakthrough. Nothing tangible changed when Neil Armstrong's foot dug into the lunar dust and his eyes turned back at us. We didn't get faster wheels or smaller machines or more effective medicine. But we changed, fundamentally. What had been unknown, was known. What had been unseen was seen. And our human horizon popped out a quarter million miles. Forever, we would see the Earth differently, because we had seen it from someplace truly foreign.
This is why Mars is important. When we get a human to Mars -- in the next few decades, NASA has predicted -- our horizon will expand 1,000 times farther, and it will never go back.
Watching the first images from the rover, Curiosity, which landed on Mars last month, I was reminded of a short story by Ray Bradbury called "Mars Is Heaven!" In it, Mars is populated by aliens who fool visiting Earthlings into thinking they're in a familiar environment before murdering them. It's about how stupid nostalgia is, how it tricks us into wanting things that were never that great in the first place. What strikes me about the story is that, just over 60 years ago, someone could seriously write about aliens on Mars.
Can you imagine what it was like then? Mars was an impossible frontier; we wouldn't even have decent pictures of the planet until almost 20 years after the story was published. Now it reads like a fairy tale in which the moon is made of cheese, or the sun is a horse-drawn chariot bearing a god, or the stars move in crystal spheres around the sky.
When humanity was in its infancy, we thought the universe revolved around us. Then, with Copernicus, we aged into heliocentrism, became aware we were one of a family of planets inside the walls of our house, the solar system. Nearby stars gather like a town, rotating through the galaxy, our country. Clusters are like continents. We realized in stages that we were very insignificant. And then, almost like grown-ups, we pulled our boots on and began to try to leave a significant mark anyway.
We don't get anywhere by staying home from Mars. By pushing our little mine carts around the earth and making speedier mine carts, by connecting long pipes to communicate with one another and then creating better pipes to shout down, louder ways to shout. All of our squabbles with other humans and all of our possessions here on earth, the things we make faster, easier, smaller, really mean very little. How could they, when the universe is so big? Significance is in science -- not the science that leads to better mine carts and more efficient shouting, but the science that leads to more ideas.
Remember Plato's allegory of the cave. In the cave, the people look at shadows moving on the wall. They watch the shadows move, and they think they're alive. What if they could go outside and see the sun? That's us, moving from the Earth to the Moon. That's Neil Armstrong, who died at the age of 82 last weekend, standing on the Moon and looking back at Earth.
The thing about the cave is, it's not just one cave. It's more caves, and more, all nested within one another. The Moon was our first cave; Mars will be next. And then there will be another cave, and another.
When people scoff at sending humans to Mars and say that pictures of wheel marks on a red desert are not worth the trouble when there are so many things here at home that we could be spending money on, it makes me claustrophobic. It's as if we're trying, out of guilt or shame, to crawl back into the cave and watch the shadows on the wall. We're trying to stay children in our parents' house, knowing that the road leads to town, and then to another town. We're saying, "Look, we made a really great toilet that flushes itself! Remember that printing press? That was pretty neat. We even made pyramids -- those things are huge! Can't we just be happy with making a great toilet even greater? Do we really have to go to Mars?"
But Mars is waiting. It spins now outside our human reach. We must realize that the work of growing up is not something we can cut when the budget gets tight. It is mission critical, for the intellectual life of the species, for the future of humans, not to stagnate, not to wither, but to stretch, and reach, and always to expand.
Lydia Netzer is the author of the novel "Shine Shine Shine." She wrote this for The New York Times. First Published September 2, 2012 4:00 AM