This is the solar system in which you live — minus the Sun, Pluto, and a boatload of ring particles, asteroids, moons, and comets. All these planets have been visited by spacecraft missions sent from Earth sometime in the last 40 years. Why do we routinely fling probes out to these worlds when it would be far more fun to simply visit them? Well, for starters, visiting other planets — even our own Moon — isn’t a simple proposition. I wish it were — science fiction stories make it seem easy, but they don’t always dwell in the millions of details that would accompany each crew into space. Sending people to space is a tough thing to do but eventually we’ll be out there walking the dusty plains of Mars and scooting above the rings of Saturn.

Humans have the invaluable eye of experience and judgment, which all explorers use to analyze their surroundings and figure out how things got to be the way they are. It’s one thing to look at a canyon in photographs taken by an orbiting spacecraft, but quite another to drive into that canyon, hike its walls, and analyze soil samples for some understanding of its chemical and geological evolution. We can send machines to do the grunt work, but they can’t do the analysis that a well-trained scientist can do in a single glance.

But, people need special environmental suits and spacecraft to protect them from the hostile environment of interplanetary space and the conditions at other planets. There’s no way right now, for example, that we can send anybody to the surface of Venus. We simply don’t have the technology put together to shelter people from the high temperatures and pressures that exist at the Venerian surface. Actually, right now we don’t even have an interplanetary spacecraft that can get them to the other planets. It’s far easier to send packages of specially-hardened electronics that can stand up to the punishing rigors of planetary exploration. It’s one thing to fry a spacecraft in the high radiation environment at Jupiter, for example, but obviously a far different proposition risk turning human explorers into crispy critters.

For now, however, we have to work with images and data sent back from our flotilla of planetary missions. We still learn a lot, and in a way, we’ll be better prepared for the time when our children and grandchildren are out there with pickaxes and soil sample kits doing the kinds of hands-on geology field trips that we can only dream of today.