The Great Era Of Space Exploration Is Just Beginning

Every new world we explore is surprising, interesting, magnificent in its own way. Pluto and its big moon Charon are no exceptions: even with just a tiny fraction of the data we’ll get from New Horizons, scientists and nonscientists alike were amazed. It was a great day and a landmark achievement for the engineers and scientists who built the probe, plotted its course across the Solar System, and made it possible to see images like this one: On July 14, we are to clear the last of the big hills. After a journey of nine and a half years and three billion miles, the New Horizons spacecraft is to go past Pluto, once the ninth and outermost planet, the last of the known worlds to be explored. This is the beginning of the end of a phase of human exploration. The crawling-out-of-our-cradle-and-looking-around part is over….

But the inventory of major planets — whether you count Pluto as one of those or not — is about to be done. None of us alive today will see a new planet up close for the first time again. In some sense, this is, as Alan Stern, the leader of the New Horizons mission, says, “the last picture show.”

Overbye writes far more eloquently than I do, but (to put it bluntly) he’s wrong.

The first problem: there are a lot of places in the Solar System we haven’t sent probes yet, which even Overbye admits. Our cosmic neighborhood has many moons — including some larger than Pluto! — that are equally worthy of investigation, but we only have snapshots from a Voyager flyby. And along with Pluto, we have a veritable swarm of small icy worlds, each of which looks different. Pluto is the biggest, but Eris is the most massive, Makemake is a relatively dark red color, Haumea is shaped like a dinosaur egg (well, kinda) that tumbles end over end, Quaoar is named “Quaoar”. Then there’s Sedna, so far out that we don’t quite know why it’s there.

These worlds are all small enough that at best they appear as a few pixels in our strongest telescopes. Pluto was that way until just a few weeks ago, and now we can make maps of it. Don’t these other worlds deserve study too? We don’t know what we’ll find there, and that’s the beauty of exploration. Just figuring out why Pluto is different than Charon is different than Eris or Makemake or Quaoar … that tells us about the early days of the Solar System and the chemistry of the cloud that made Earth and the other planets. The surprises on Pluto are because we don’t know all the answers. Science is about learning new things, if it is about any one thing.

The Solar System had “nine planets” for 76 years, shorter than many human memories. Kids born in this century will not really know “nine planets”: they’ll know eight plus the dwarf planets or whatever classification we end up with, if things get shifted around again. If Pluto is reinstated, we’ll also get Eris, Makemake, Haumea, and probably a dozen other small worlds as a bonus. The Solar System is a richer place than it looked to us 20 years ago.

And that’s just the bigger worlds out there. If we include irregularly shaped worlds — comets like Comet 67P, asteroids like Itokawa, centaurs like Chariklo, and all the wonderful potato moons like Hyperion — the list of interesting places grows huge. The arbitrary choice of “nine planets” worthy of exploration misses nearly everything worth studying, and it’s not even counting the giant planets we’ve only visited once briefly, and still have much to learn about: Uranus and Neptune.

I think the real problem with Overbye’s piece ultimately is a kind of lack of imagination. He sees the Solar System like he sees the hills of the mythical Wild West of his childhood’s movies, where the cowboy rides across the open range (never mind that the open range was a myth created to ignore the indigenous Native American groups already living there). The frontier closed; New Horizons visited Pluto, the ninth planet of the Solar System of his childhood; and that’s it. Never mind that we’ve found a lot more since then: what matters is that we’ve visited each of the “planets” he learned in school. It’s a self-centered view.