|Image of Pluto captured by New Horizons on July 7th, 2015 at a distance|
of ~5 million miles.
A great video was posted on the New York Times website a few days ago, highlighting the New Horizons mission and interviewing astronomers and planetary scientists about the meaning of the Pluto encounter. In the video the mission is framed as the end of an era, the final voyage to complete our 50-year reconnaissance of the Solar System. And in a sense it's true; we have visited all the major worlds, as well as a few minor ones, and Pluto is the last stop on the traditional tour.
All the same that felt funny to me saying we've completed our reconnaissance of the Solar System. I have always defended the 2006 IAU decision to reclassify Pluto as a dwarf planet... not because the definition isn't problematic, but because the classification begs the question, "why is Pluto a dwarf planet?" The answer of course is that there is a whole host of other worlds out there, equally real and equally exciting, that you just didn't get the chance to learn about in fourth grade because no one knew they were there! There is Eris, Orcus, Quaoar, Haumea, Makemake, and distant Sedna on its highly elliptical orbit-- to name just a few of the more prominent Kuiper Belt objects. Why should Pluto get all the glory? It seems to me that for many people nostalgia for the wonder they felt as a kid trumps the wonder of what is to come, the wonder of the unknown. But these worlds await our exploration! There is so much left for us to discover. And lest you think that if you've seen one, you've seen them all, consider the curious array of moons that orbit Jupiter and Saturn. There is an astonishing variety of worlds in our Solar System, and there is good reason to think that what we will find in the coming years in the depths of Trans-Neptunian space will be startlingly different than what's come before.
Still, even if this isn't really the end of our forays into deep space exploration, it is indeed the end of an era. This will be the last time for a very long time that we see a mission to the outer solar system. There was a thirty year gap between the launch of New Horizons and the launch of Voyager, the last spacecraft to venture out beyond Saturn, and there are no real plans in the works for anything to follow along these lines. Will it be another thirty years until we take another shot at exploring the vast depths of our own Solar System? If so we cannot expect any more close-up images of these worlds until about 2050 or so. So better soak it up while you can. Of course we can hope that next-generation telescopes, ones currently under construction or in the planning phases, will yield in the years to come imaging of the distant dwarf planet retinue spectacularly better than present technology, but even then we'll have to wait at least a decade or so for those to come online, and we cannot expect anything like the breathtaking detail that's in store for us with the Pluto flyby in a few days.
Astronomy tends to be that way: we're always looking at what's coming next, but we usually have to wait an awfully long time for it to come. It's the combination of budgetary restrictions, the limited supply of expertise, and the extensive planning involved that makes space missions and revolutionary telescope projects take so long. In science it often happens that scientists work for many years on a single project, and in some cases a scientist will die before he or she see the fruits of that labor. In a sense that's true of every scientist, as the work always outlives the man or woman behind it, and proves useful to the next generation long after they've gone. You might feel a bit sad to think about those scientists never getting to see what wonders may be wrought from their work, but for myself I find it to be humbling, and invigorating. We are all just a small piece of this puzzle, but we are part of a collective enterprise that will be making remarkable discoveries and improving our understanding the universe long after we've turned to dust. So long as we humans can preserve our way of life, the body of scientific knowledge will be ever increasing, and each little contribution lives on.
I will always be impatient for the next mission. I can't wait to see probes sent to Europa and Titan and Enceladus. I can't wait to see a manned mission to Mars. But the anticipation is also thrilling. It spurs the imagination and generates wonder in a new generation of scientists. We have to leave some mysteries for the future, after all.
For now, Pluto is the present we get to open in a few days. It's been a long time coming, and it's going to be spectacular.
Thanks for reading, and staying with me during this rather long hiatus. I'm rarely moved to write much these days, but I remain active on Twitter (a much less demanding medium) so please follow me there if you feel so inclined. In any case, I hope to get back to writing more regularly, one of these days.