Watch the TEDTalk that inspired this post.
Is the Earth in imminent danger from an asteroid collision? Some doomsday prophecies suggest as much, and scientists don't entirely disagree even as they remind us of the infrequency of such events (on the order of millennia) and the long odds against an impact of sufficient magnitude to imperil life on Earth. So while the threat is not zero, it's also a remote one that pales before human-caused existential threats such as those posed by cascading climate change or the prospect of thermonuclear war.
Perhaps, then, it's simply a matter of asking the question in the right way. Is the Earth menaced by asteroids? Given the news story making the rounds last spring about plans by a start-up corporation (with some very high-powered backers) to begin mining near-earth asteroids for water and precious metals, it might actually be the other way around: asteroids are in immediate jeopardy of human exploitation. The difference is that we can choose whether to tamper with asteroids; they cannot.
It is this sense of intentionality that I find most intriguing. Should we take measures to thwart an impending asteroid collision if we're able to do so? Of course. But if we expend too much energy in anticipation of such a rare and unlikely event, then we're drawing resources away from more homegrown challenges that are far less remote and much more likely to occur in our lifetimes.
NASA surveys indicate that there are about 5000 potentially hazardous asteroids (PHAs) in near-earth orbit. By comparison, it's estimated that there are around 25,000 nuclear warheads on the planet. We can't say for certain how many of these it would take to annihilate life on Earth altogether; scenarios that factor in not only blast damage but also radiation and the prospect of a "nuclear winter" (in which the sun is blotted out for years or more) suggest that the number is fewer than we might like to contemplate.
Indeed, contemplating such scenarios is seemingly part of our nature, but again perhaps we're contemplating the wrong thing. Asteroids are not merely dangerous objects to fuel our apocalyptic fantasies and science-fiction screenplays. They are also part of the wondrous tapestry from whence our very lives and existence originate. As NASA observes in the description of its Near Earth Object Program:
"As the primitive, leftover building blocks of the solar system formation process, comets and asteroids offer clues to the chemical mixture from which the planets formed some 4.6 billion years ago. If we wish to know the composition of the primordial mixture from which the planets formed, then we must determine the chemical constituents of the leftover debris from this formation process -- the comets and asteroids."
Taking this logic one small step further, we can surmise that asteroids may even hold the secret to the origins of life on Earth itself, perhaps contributing organic compounds and the building blocks of water to the Earth as it was forming, thus seeding it for the eventual existence of life as we know it. It would be an ultimate irony -- albeit not an atypical one for a culture obsessed with its own demise -- if we were to take extreme measures (e.g., nuclear weapons) to obliterate an asteroid that was deemed a threat, since we might actually be nuking the cosmic equivalent of our own progenitor.Astrocide, anyone?
I guess this isn't so farfetched after all, considering what we already do to one another when we deem someone a threat to our way of life: we "go nuclear" (in the vernacular) at the least. Credible threats, even nascent ones that haven't yet fully emerged, are met with unilateral preemptive action. Might the logic of the U.S. invasion of Iraq be applied similarly to an asteroid identified as a potential threat? In the case of Iraq, we were treated to a "Shock and Awe" campaign that included the use of a MOAB (the "mother of all bombs"), and that was just the kick-off of what turned into a devastating bloodbath.
Luckily, when it comes to asteroids, at least we have politically expedient alternatives to the use of overwhelming force. As described by astronomer Phil Plait in his informative and humorous TEDx talk, a more fruitful course of action might be a "velvet gloves" approach in which a small tug from a modest-sized probe sent to synch up with the asteroid is enough to gently nudge it into a stable and non-threatening orbit. (Plait argues that this could also allow for mining said asteroid, which raises other issues, as I've previously noted.)
In principle, the application of gentle persuasion rather than brute force is a wiser choice and portends tapping into our better instincts as a species. In fact, NASA's Goddard Space Flight Center (GSFC) set up a webpage in 1998 to address growing concerns about possible asteroid collisions with Earth. In the most likely of the unlikely scenarios, we would have ample time to collectively respond to the crisis, and it could even be a positive experience for humankind, as the GSFC observes: "It would be a project for all the world's nations to take part in. It could be a globally unifying event." (For contrast's sake, consider the dismissive, cold-shouldered tone of the bizarre blog post on USA.gov, intended to dispel rumors about the so-called Mayan Apocalypse: "The world will not end on ... any day in 2012." Comforting!)
So let's bring the conversation (literally) back down to Earth. Asteroids may pose a threat, but they are merely among a spectrum of threats that include a multitude of our own making. If the danger of an asteroid collision with the Earth has the potential to unite humankind and remind us of our interconnected lives and shared destinies, then we can surmise that more mundane threats could potentially do the same. Ultimately, the most profound collision would be one that unites humankind with our humanity.
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