Sandia researcher Mark Boslough with an image from a simulated mid-air explosion of an asteroid. (Credit: Randy Montoya/Sandia) Monday marks the 100th anniversary of the moment when something roared through the empty skies over Siberia and exploded, blasting forests for hundreds of square miles. More such incoming space rocks are inevitable. Are we ready? No.
Last year, scientists at the Sandia National Laboratories in New Mexico did some simulations (here’s one virtual Tunguska-like fireball) and proposed that the object, most likely an asteroid, could well have been just a few dozen yards across. That is distressing, disaster experts say, because near-earth objects this size are presumed to be much more common than larger space rocks, and they are too small to be easily spotted long in advance with the telescopes used to track such debris. (For more, New Scientist has a nice Tunguska overview.)
So while the odds are that the next Tunguska-size object will arrive over the ocean or Earth’s still-vast stretches of empty land, there’s no reason why it couldn’t explode over Chicago or Taipei. The big near-Earth objects, or NEO’s, are being tracked fairly well, but quite a few experts on space, risk, and resilience say we’d better start sifting for the small ones, too. And then there’s the matter of doing something about it, so the endgame looks more like “Armageddon” than “Deep Impact.” The world is in the early stages of devising methods for deflecting asteroids. To get a sense of what’s out there, have a look, too, at this mesmerizing animated graphic showing just how much space rock is floating around (of the size astronomers are currently tracking, at least):
Animation linked with permission, created by the Center for Minor Planets,the Smithsonian Astrophysical Observatory. Click for details.
The graphic shows known flybys of large asteroids within 12 million miles of Earth — the blue dot in the center — in 2002. The animation was created by Gareth Williams of the Minor Planet Center at the Smithsonian Astrophysical Observatory, under the auspices of the International Astronomical Union). These are somewhat close calls by Solar System standards and don’t include objects anywhere near the small size of whatever blew up over Siberia 100 years ago.
I asked Rusty Schweickart, an Apollo 9 astronaut who’s become a leading voice in the push for taking space rocks seriously, to weigh in on the centennial of Tunguska, and he wrote a whimsical letter that explains the risk and possible response by “someone” who took a little action back in 1908. Click to have a look.
Rusty Schweickart, an Apollo astronaut, has been pressing for more work to spot and deflect earthbound asteroids. He spoke about the risk at the Hayden Planetarium in 2005. (Jennifer S. Altman for The New York Times)Rusty Schweickart of the B612 Foundation wrote this imagined letter to explain the situation:
Dear Sasha & Tatiana:
Well, 100 years have now passed and I finally feel comfortable in letting you know that I really appreciate the sacrifice you made (or your family that might have been made) when I slowed the Earth’s rotation momentarily back in late June 1908. That’s not something I normally do(!) but in that case I really felt I had to intervene.
You see, what’s now referred to as the Tunguska impactor, a smallish asteroid about 40 meters in diameter, was headed for an impact with Earth, directly over Moscow. It would have been a disaster of truly huge proportions, and I just couldn’t stomach that given what Russia was going through at the time. So I slowed the Earth down for a bit… just a few minutes per day for a few weeks. As a result the asteroid hit way out in the middle of Siberia instead of directly over Moscow.
Now there are surely millions of present day Muscovites who owe their lives to the sacrifice that your great-grandfather made in taking the hit for them. In all likelihood he and your great-grandmother would have had many more children than just your grandmother, but there he was in the most desolate section of Siberia, tending his reindeer herd, far, far from everyone else. I’m truly sorry that you don’t have many more cousins to celebrate the holidays with, but in the larger scheme of things it seemed to be the right thing to do at the time.
But I’m really tired of this kind of intervention; it just takes too much out of old fate to pull of this kind of thing in the future. Since so much has happened in the past 100 years in terms of technology development, you and your fellows around the planet are really able to handle this kind of thing yourselves. I mean, after all, your telescopes are now finding the larger asteroids that make close passes by Earth, and soon they’ll be finding the smaller ones like the Tunguska impactor. At least they could be doing that.
And as you know shoving an asteroid slightly off its course is far simpler (and cheaper) than going out to take pictures of yet another of Saturn’s moons!
So I’m pretty content to let the celestial clockwork and human ingenuity run their course undisturbed by pro-active fate. From my perspective it seems that with all the tools required, both an early warning capability and the ability to intervene to slightly alter an asteroid’s orbit, humanity ought to be able to get the job done without me mucking about with space-time.
So good luck. All it really takes is for you to convince your fellow human beings that they really are all related and really can, by coming to a simple agreement to act in concert, protect both themselves and future human (and fellow creatures’) generations by sharing the risk of slightly shrinking or enlarging any threatening asteroid’s orbit so that it misses the Earth. Really, you can do this, provided you can all get together. Yes, I know, that’s a big challenge. But let me tell you, it’s a far smaller feat for you to slightly alter the shape of the local universe than it is for me to slow down the rotation of the Earth!
Good luck.
Fate
In his testimony on hazardous asteroids before the House Science Committee last November, Mr. Schweickart, representing his B612 Foundation, included this closing line to lawmakers:
NEOs are part of nature. A NEO impact is a natural hazard in much the same way as are hurricanes, tsunamis, floods, etc. NEO impacts are deceptively infrequent, yet devastating at potentially unimaginable levels. NEOs are however not our enemies. We do not need to “defend” against NEOs, we need to protect ourselves from their occasional impact, as we do with other natural hazards. Unlike other natural hazards, however, NEO impacts can be predicted well ahead of time and actually prevented from occurring. If we live up to our responsibility, if we wisely use our amazing technology, and if we are mature enough, as a nation and as a community of nations, there may never again be a substantially damaging asteroid impact on the Earth. We have the ability to make ourselves safe from cosmic extinction. If we cannot manage to meet this challenge, we will, in my opinion, have failed to meet our evolutionary responsibility.
A few years earlier, I’d met him at a conference in Boulder, Colo. Mr. Schweickart had just given testimony before a a Senate committee, and told a depressing story about his conversations with staff members shortly afterward. To a person, they said the lawmakers they worked for were convinced of the threat and need to invest more in protection. And to a person, he recalled, they apologized that new money was unlikely because making the deflection of asteroids a priority might backfire in reelection campaigns.
Last year in an earlier post on asteroid impacts, Mr. Schweickart mused on an issue at the heart of Dot Earth — how political systems, reflecting human nature, still seem to be having a hard time integrating scientific understanding, uncertainties and all, in ways that result in policies and investments that could blunt risks while fostering prosperity.
That same dynamic (or lack of dynamics) is at the heart of the climate-energy challenge, but also this one, and others. For instance, political imperatives are prompting the rebuilding of sections of New Orleans that coastal and ocean experts say are inevitably going to be immersed.
In the end, that is why Dot Earth is not a climate blog, or an environment blog. It is an exploration of how humans, on the road toward a population of 9 billion, more or less, can limit losses from “slow drips” and “hard knocks” of all kinds — from indoor air pollution and diarrhea to asteroids and global warming.
Do we have the technical capacity to spot and divert the next Tunguska or a bigger cousin? Yes.
Are actions keeping pace with emerging understanding of this threat?
Mr. Schweickart says it’s not even close.
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