Mar 13, 2007 07:26 PM
Everybody duck and cover. Last week NASA shrugged and told Congress that it neither has the funding nor the resources to meet its goal of identifying 90 percent of near-Earth asteroids (NEAs) 150 yards or more in diameter by 2020.
It seems that NASA has passed the buck it claims it doesn't have to other space agencies, institutions and facilities, saying NEA tracking is not a question of feasibility but funding. This includes not having available dedicated telescopes, including the Arecibo telescope in Puerto Rico, which will probably close or have its operations severely downgraded by 2011. (See this and this.) It is bad enough that we may lose Arecibo, which is one of the best-suited for the job of planetary watchdog, but NASA says it will have to rely on the kindness of others to do even the preliminary work to meet the goals called for by Congress in NASA's 2005 authorization bill.
And, though a killer-asteroid is not currently on track to vaporize Pretoria or Peoria or anywhere, at least as far as we know, it did not say who exactly would be funding research on NEA diversion and destruction technology should this situation ever visit itself upon the only planet we have. NASA's balk, according to a March 9 story in the Washington Post did not sit too well with Rep. Bart Gordon (D–Tenn.), the chairman of the House Committee on Science and Technology, who said: "We are still reviewing the report, but it's clear that NASA's recommended approach isn't a credible plan to achieve the goal specified in the NASA Authorization Act." The Committee will continue to pursue this issue in the coming year with the goal of obtaining a more responsive approach," he declared.
It is a sad day when our premier agency of exploration shows less imagination and foresight than an elected government official.
The somewhat lethargic pace of asteroid accounting was discussed at where else but the Planetary Defense Conference, held last week where the defense of our globe was outlined in the form of scholarly papers and speeches about tracking and cataloguing NEAs, determining if one of these beasts was headed our way, and, if so, how to deflect or destroy it. And in February the Association of Space Explorers, an exclusive group of over 300 space farers from 30 nations said the U.N. should concert global action to stop the menace from NEAs.
Asteroids come in all sizes—and here size does matter. The risk from the continent- or world-busting one-half- to one-kilometer-wide boulders of mass destruction is very low, and civilization-snuffing monster asteroids are estimated, according to the conference's chairman, William Ailor, to number about 1,000 (700 of which have been discovered) and none seem to currently be setting their stony sights on the headquarters of Homo sapiens.
Of more concern, and less of a long shot, are the smaller 100- to 500- meter-size NEAs. NASA estimates there are about 100,000 of these roughly football-stadium-size brutes. As of now, there are 130 NEAs that the Jet Propulsion Laboratory's Sentry System lists as "potential impact risks."
In the same Post article, another conference speaker, Pete Worden, director of NASA's Ames Research Center, estimated that a 100-meter Tunguska-size asteroid hitting Washington, D.C., would destroy the city and its suburbs, ending the era of big government to the potential delight of many, but at a cost to humanity that is, hopefully, unacceptable to all. Still, should we worry if the likelihood of "death by asteroid" is about as low as dying in an airplane crash if one flies once a year (yet, I'd think, still much more likely than the odds of everybody actually turning off their cell phones in a movie theater). That said, he estimated it would probably cost about $1 billion to meet the congressional goal of identifying 90 percent of NEAs 150 yards or more in diameter by 2020. "We know how to find objects most likely to be a problem," he said in the Post article. "But we do not yet have congressional funding to move ahead."
Sad to say, it is easier to find Superdome-size rocks in the inky blackness of space than it is to find funding in the red-ink abyss of a government budget that always seems to have enough funding, or at least debt service, for wars of choice and bridges to nowhere, whereas NASA's budget seems to be frozen year after year. And though NASA Administrator Mike Griffin is doing a bang-up job pushing forward with the "Vision for Space Exploration" to put humanity back on the Moon by 2020, cuts have to be made elsewhere unless more funding is added. Where is big government when you need it?
Enter Apophis But isn't this protection a luxury when there are so many other problems to solve? True, there is nothing threatening us at this juncture. Well, probably not. We cannot know until we observe, track and catalogue. And there is a NEA to watch—Apophis 2004 MN4. At about 1,000 feet (300 meters) across, it is slated in a one-in-45,000 chance to be in the same place as some location on Earth in 2036. Though this sounds like a low risk, the problem is that the odds are not static. In fact, Apophis is a good example of the lead time necessary to determine a threat and to make the costly decision to avert it—or, not to: JPL in 2006, after observations of Apophis with the Arecibo radio telescope, reduced the odds of a 2036 hit from one in 5,500 to one in 24,000 after determining that its speed was six millimeters per second different than expected. Problem solved? Not. Further measurements will be necessary and will be taken in 2013. This time, the odds were reduced, next time they could be increased. It comes down to a "keyhole"— an area as small as 600 meters across—near Earth that a NEA passes through that can perturb its orbit toward a collision on subsequent Earth-orbit crossing passes. Luckily, we know about this critter and can keep an eye on it. But what about the other 129 "potential impact risks" on JPL's list?
To be fair, NASA is not ignoring the possibility that Apophis could be trouble. In answer to a 2005 letter of concern from the B612 Foundation, whose mission is "To significantly alter the orbit of an asteroid, in a controlled manner, by 2015," NASA set a timetable for handling Apophis.
And they and others continue to watch Apophis closely—observers even know where it will be on April 13, 2029: silently zipping above our tiny Earthling lives at about the altitude of the communications satellites that will probably be diverting our attention to more important things, like the American Idol 2029 loop playing on our cerebral implant PDAs while we loll on a fine early spring afternoon at a favorite Appalachian Coast beach (assuming our response to climate change threat had been similarly lethargic). And, on this closer pass Apophis will be in an even better position for its succeeding orbit to be altered in an unpredictable way—one that might put it on course to whack our world on its next orbit in 2036.
Basically, like detecting cancer early, the sooner we find a malignant NEA, the more of a chance we will have to assess it and, if it is on a deadly course, change it. No matter what tactics we use to divert or destroy it, from detonating a nuke to crashing a probe into it, or even taking a less satisfying and more pacifistic approach preferred by asteroid-huggers: orbiting it with a vehicle that would change its orbit just enough to avoid an impact, not to mention other more exotic options like a gravitational tractor, it will be easier to do when it comes to effecting changes in its path and speed measured in meters and millimeters per second. The difference between early tracking and doing nothing (or finding out after it is too late), may be that of a brilliant spectacle of a diverted asteroid in the daytime sky that we can all coo at in wonderment, or "Hiroshima—coming to city near you."
Remember Tunguska, Chicxulub and Arizona! Though efforts are being made, perhaps we will need more TV specials on Tunguska and the dinocide-causing asteroid that created Chicxulub Crater in the Yucatan or mandatory student field trips to visit Meteor Crater in Arizona. It is always sobering to picture this well-preserved bullet hole in the Arizona desert smoldering in the middle of your suburb. Perhaps we need to think of the threat from the skies the way people who live near water see the potential for storms, floods and tsunamis. Because of a tsunami warning system, the people who live around the Pacific's "ring of fire" are safer than those who live around the Indian Ocean, even though there are far more tsunami's in the Pacific region. When Indonesia experienced the horrible tsunami of December 2004, it was the first major event of that kind since Krakatoa blew up in 1883. Though there are less tsunamis in the Indian Ocean, when there are big ones and no warning, hundreds of thousands die. Of course there are fewer deaths in the Pacific Basin because of lower population density, but our response after that awful December day was to start building a similar warning system for the Indian Ocean region.
Now the thing about such a warning system is that although it cannot stop a tsunami, it can give people enough time to get out of the way. Property may be destroyed, but human carnage is averted. The same can be said about investing billions in weather satellites—if only they had existed before the hurricane that killed over 5,000 people in Galveston in 1900.
Looking at these systems, a NEA warning and mitigation system looks like even a better deal: if we can see the potential disaster, we not only can prepare, we can preempt it early by slightly changing the NEA's orbital speed. Too bad we can't do this with hurricanes. Yet this still would be comparable to New Orleans not only having ample warning time from weather forecasts to predict Hurricane Katrina's path (albeit city officials didn't use it well), but also if leaders had invested in the proper levee system that could hold back the oncoming surge from a category 4 hurricane. The equivalent in the case of NEAs would be investment in asteroid diversion technology and techniques should they be needed if tracking predicts an impact. With enough lead time, we may even have options to try to change the orbits of massive planet-busters to keep them on righteous paths.
The Tunguska event happened only two years after the 1906 San Francisco earthquake when an asteroid detonated in the air over a bleak expanse of Siberian taiga. Trees were flattened and some people and animals died. If it would have hit a few hours earlier or later a city might have been devastated. The 99 years that have passed seem like a long time, but it also means we have gone a while without an impact. The main point is: asteroids happen.
Up until 2004 the Indian Ocean region could enjoy the fact it had saved millions, maybe billions, of dollars by not installing a tsunami warning system. Think of how much we have all saved up to now by only minimally investing in planetary defense.
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