Remember Asteroid 2004 MN4? Quite possibly not -- news about it was overshadowed by the late-December tsunami. 2004 MN4 is an Earth-orbit-crossing asteroid that, for several days in late December, appeared to be on target to hit the Earth in 2029. Early estimates of chances of impact grew higher as the orbital calculations improved, something that hadn't happened with previous asteroid early warnings; only after some slightly-panicked number crunching did astronomers figure out that 2004 MN4 wouldn't hit the Earth, but would instead come within 23,000 miles -- the astronomical equivalent of having a bullet whiz right past your ear.
We can all breathe a big sigh of relief, right? Well, not so fast. When something comes that close to a planet's gravity well, its path shifts. With our current observations about 2004 MN4, astronomers estimate that MN4 has a 1 in 23,000 chance of hitting the Earth in 2035 and a 1 in 14,000 chance of hitting in 2036. We'd be able to calculate precisely whether or not the asteroid will hit after it passes... but at that point, if we found that it would hit, six or seven years is simply not enough time to do anything about it. Hollywood notwithstanding, it really doesn't help to blow an asteroid up -- you just end up being hit by a larger number of chunks with the same energy. The real solution is pushing the rock off-course... but that would take longer than we'd have. And when 2004 MN4 hit, it would unleash nearly a gigaton of energy.
[Schweickart] unveiled his proposal Friday at the International Space Development Conference in Arlington, Virginia.
The proposal calls for a $300 million mission to land a transponder on the asteroid, a 1,050-foot-wide body known as 2004 MN4. Signals from the transponder would be used to pinpoint the asteroid's trajectory and determine whether it will strike Earth or simply zoom past.
[...] "This asteroid is exceptional in terms of the accuracy of the data that we need to have on it," he said. "Normal tracking will not do that job."
Schweickart himself believes that an impact is unlikely. However, in his report, he provides a rough estimate of the potential damages, noting that a splashdown in the Pacific Ocean could create a tsunami twice the size of the recent Indian Ocean tsunami.
As space missions go, $300 million isn't all that big -- it's less than the cost of a single (pre-Columbia) space shuttle launch. We're getting to be pretty good at aiming satellites at space objects like asteroids and comets; what would make this launch complex is the need for a relatively soft landing to keep the transponder intact.
But the bigger issue is getting people to think about long-payoff prevention. The reason we would need to launch a transponder soon is that, should we discover 2004 MN4 was going to impact the Earth, it would take steady pushing for months a decade or more in advance to make sure it missed. Moreover, it's not like we have ready-made asteroid pushing satellites on the shelf -- designing, testing and building something able to put out a steady impulse for weeks at a time would itself take years to do. Frankly, even if we launched a transponder this year, we would be cutting it close.
We can see the same logic at work with other large-scale geosystem threats, global warming being the most obvious. The real impact of global warming-induced climate disruption won't be felt for decades, but if we wait until it's starting to hit hard, it's far too late. As it stands now, it's likely already too late to prevent serious warming, but the difference between what would happen even if we make huge steps towards greenhouse gas emission reduction and what would happen if we continue to hesitate will be enormous -- in 50 years.
A common piece of reasoning among some denialists is that, if we wait before doing anything about global warming, the technologies available to reduce greenhouse gases and improve efficiency will be far better than what we have now. That's both true and irrelevant -- it's a kind of thinking based on short-term action-response cycles. If we wait until the technology is better (a perpetual wait, as even better technology can always be seen just over the horizon), we have also added more years' worth of unrestrained carbon load into the atmosphere, carbon that stays there for centuries, and will warm the Earth further, no matter how clean the future technology is.
And that, of course, depends on the future tech being significantly better than today's. WorldChanging often appears to be a technology enthusiasts' site, and that is partially true -- but we also recognize that technology is a social phenomenon, and quite often social factors can mitigate or reverse seemingly inevitable technological developments. In short, waiting for technology to get better before acting doesn't just allow the problem to get far worse, it runs the risk of the technology not getting better in time.
The same logic applies to dealing with 2004 MN4. Some will undoubtedly argue that spending $300 million now to improve our tracking of something that almost certainly won't hit the Earth is silly, given that our technological abilities for handling MN4 would be far greater in the 2030s. A tempting argument -- $300 million could go a long way to pay for other programs -- but an altogether dangerous one.
We need to be thinking in the long term not just to see opportunities down the road, but to see the ways in which acting now can forestall or prevent disaster later. Long-term thinking is by far the best possible form of planetary life insurance. We need more of it, and we need it soon.
A free ride on an asteroid sounds fantastic, just by itself.
Of course one gigaton sounds like a lot of energy for an energy starved planet, no?
Daniel's comment makes me think we should land a device which could use the difference in speed/direction between earth and this rock and convert it into some useable energie source...
A gigaton is approximately 4 quads of energy[*]; in the course of a year, humanity uses about 400 quads of energy. If you think it's worthwhile to build a huge energy infrastructure to capture 3.6 day's worth of our needs... and use it just once....
[*] Calculation: 1e9 tonness * 1e6 grams/tonne * 1000 calories/gram TNT * 4.184 joules/calorie / 1054.4 joules/BTU = 3.968e15 BTU ~= 4 quads.
How about not pushing it off course, but slowing it down gradually and bringing it into close Earth orbit, hence giving us either the basis for a space elevator (as detailed here: http://www.spaceelevator.com/) or for mining purposes?