Peregrinus Orior

by Robertson, John

  “Mr. President, I will,” confirmed the advisor. “I understand now what people mean when they say you’re a thoughtful decision-maker but once you’ve made up your mind you move decisively and quickly. Is that enough for today, or would you like to carry on with my Chicken Little act?”

  “Oh, let’s finish the rocks-from-the-sky story,” said James Rushton. “Now that I have the background, let’s get to the meat of the matter. Eli, with all those objects that come that close to the Earth, how big would one have to be to cause us real trouble, and how likely is that to happen in the next ten years?”

  “Mr. President, ones that are big enough to do catastrophic damage are statistically very rare,” responded Eli, moving his laptop closer to the president to display more images. “The sort of sensational event depicted in this artist’s conception of a killer asteroid strike may have occurred a few times in the first one or two billion years of the Earth’s history. By now, after about four and a half billion years of the Earth sweeping a path around the Sun with its gravitational attraction broom, it has pretty much cleaned up the neighborhood of objects of this magnitude, along with the other seven planets, including the four gas giants with their much bigger brooms. Yet, the potential certainly exists for an impact large enough to be catastrophic from a human perspective. The so-called dinosaur killer struck the Yucatán peninsula near the location of the current town of Chicxulub sixty-five million years ago, and the energy released changed the climate so radically that it caused the extinction of many species including all the dinosaurs. That object was an asteroid about six miles in diameter and would have released the energy equivalent of one hundred trillion tons of TNT, several billion times that of the atomic bombs that destroyed Hiroshima and Nagasaki.

  “As massive as that impact sounds, for the Earth itself it was a pin prick, and not the largest it has ever experienced. However, for the life subsisting on the surface of the Earth, it was devastating beyond imagination. The initial blast and heat would have been horrific, obliterating and incinerating everything for thousands of miles. Secondary effects would have been massive over an even broader front, including reentry of enormous amounts of molten material ejected from the impact crater into space, tsunamis, volcanic eruptions and earthquakes. But the global extinctions resulted from a tertiary effect that spanned the whole world, a change in climate so profound as to make our global warming problem pale in significance. The amount of dust injected into the upper atmosphere allowed so little sunlight through that most plants died. Then the herbivores that fed on them died, followed by the carnivores that fed on the herbivores. The human race would face a similar fate to the dinosaurs, with survival possible only for small groups located at great distances from the crater, and only those who were well prepared with extensive stores of food, energy and equipment. Fortunately, this is a once-in-a-million-year event, so the risk is very low.

  “More worrisome than a dinosaur killer–sized object is the risk of a smaller but still sizeable impact, say by something a half-mile in diameter. These are estimated to occur once in a hundred thousand years, so it is still a rare event statistically, though much more likely than the dinosaur killer. An asteroid of this size would pack a punch equivalent to sixty thousand megatons of TNT. The largest nuclear bomb the United States has ever produced has only twenty-five megatons of explosive energy. The bomb that decimated Hiroshima was fifteen kilotons. So, the impact of a half-mile asteroid would still be terrible beyond all measure, likely obliterating a good part of whichever continent it impacted with primary and secondary effects. There would still be worldwide tertiary effects and resulting crop failures, but not as extensive or as prolonged as they were for the Chicxulub crater. Human civilization would survive and recover, even without extensive preparation, though fatalities would number in the hundreds of millions or even billions, and several countries would cease to exist as functional political entities.”

  The science advisor continued, “Next on the list would be an object an order of magnitude smaller still, say about a hundred yards in diameter. That is pretty small compared to the dinosaur killer, but it is still a good-sized rock, bearing in mind that it would strike at a speed of something like ten miles per second, or thirty-six thousand miles per hour. The energy release would be equivalent to about sixty megatons of TNT, or more than twice that of our largest nuclear weapons. That would still devastate a large part of any state it struck, but not an entire continent. However, the secondary effects such as earthquakes and volcanic eruptions could still adversely impact a large swath of the continent.

  “I’d be most worried about an asteroid of about one hundred yards hitting somewhere in the Western United States. That impact could stir up the Yellowstone magma chamber into an eruption. Yellowstone has the potential to inject enough ash into the atmosphere to cause global climate change similar to a full-sized dinosaur killer impact, but even a much more modest eruption could throw up enough ash to eliminate agricultural production as far as the Canadian Prairies and the U.S. Midwest, in addition to the explosive double whammy to Wyoming Idaho, and Montana over and above the impact explosion itself.

  “An impact of this size appears likely to occur about once in a thousand years, so within the ten-year period that you stipulated, still a very low risk. However, we can’t predict far in advance which ten-year interval within the next thousand years will be the one that takes the hit or where on Earth it will occur. What we can do is keep a close watch on the sky and have some advance warning of a large impact and possibly be able to deflect it or at least have a prepared impact response.

  “This table that I have printed out for you provides a handy summary of the likelihood of this spectrum of nasty outcomes.

  “Mr. President, that brings us to the point of all this background that you have patiently absorbed. Specifically, the scientific systems that we have in place to identify potential impacts of asteroids or comets with the Earth and give us some time to respond. Do we have enough time left to cover that?”

  The president had finished his lunch but encouraged Eli to continue.

  “Sir, here in the United States our efforts are managed by the Planetary Defense Coordination Office of NASA, which is located right here in Washington. These are the people I would hear from if a potential situation were to develop, and of course I would immediately arrange for you to be notified and briefed. This coordinating office has overall responsibility for early detection of potential large impacts, and of leading our response to a probable threat. They oversee NASA’s Near-Earth Object Observations Program, which watches the skies above us, and they work closely with the Jet Propulsion Laboratory. The JPL undertakes the fairly difficult computerized mathematical calculations required to estimate the orbit of a newly identified asteroid or comet and to determine whether and when it might intersect Earth’s orbit, and where Earth will be at that time. The PDCO also coordinates with similar national agencies of other countries to share information and minimize duplication of effort.

  “Mr. President, our federal government has been taking the risk of a large impact fairly seriously for several decades now, and we have some pretty sophisticated instruments keeping an eye on what is over head. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) has been in operation for more than a decade with a primary mission of detecting impact threats. It is located high up the Haleakalā volcanic crater rim on Maui with multiple large 1.8-meter aperture scopes, one of the largest digital cameras ever built, and extensive computer processing capability. Cameras and computer processing are critical for detecting moving objects, which is accomplished by comparing pictures taken at intervals of time for any change in position or brightness, and correlating with known objects.

  “More recently, the Large Synoptic Survey Telescope, located high in the Andes of north-central Chile but operated by our National Science Foundation, has now been in operation for several years. It has an 8.4-meter primary mirror and a camera more than double
the size of the Pan-STARRS. These are two of the biggest but by no means all of the hardware that is looking out for us. So, we know quite a bit about the acorns out there that could fall from the sky, and I am happy to break tradition with Chicken Little and say I believe a large impact is very unlikely in the next ten years, not just statistically but based on scientific data. Of course, if that view ever changes, you will be the first to know. However, I should mention that no large impacts doesn’t mean no close calls, and I should briefly mention Apophis before I finish.”

  Seeing a nod from James Rushton, Eli continued, “Apophis is the object that has caused the greatest level of excitement since we have been watching out for potential impacts. It is a good-sized chunk of rock, about three hundred and eight yards in diameter, so it would pack a nasty punch. It wasn’t spotted until 2004, although it inhabits Earth’s neighborhood of the solar system and comes fairly close to us fairly often. I think that with today’s instruments and observation program it would have been detected much sooner.

  “When an object is first identified, it takes several observations over an extended interval of time to calculate its path with some precision. The initial calculations, based on limited data, indicated a fairly high risk that an impact would occur twenty-five years later, in 2029, on April 13 specifically — which is of course only a year and a half from now. The combination of its size and impact-risk stimulated a lot of attention to this particular asteroid, and over time a more precise path was developed going out to 2029 and many decades beyond. So, we know now and have for more than a decade that Apophis will come very close April after next, within about twenty miles, but will not actually strike us.

  “That distance is within the orbits of many of our commercial communication satellites, and high performance jet aircraft have flown above that altitude. It will be visible to the naked eye from many places, though not from here in the US. We have been watching it very closely for the last year to make sure that it hasn’t encroached on that slim margin of safety, and it has not. In order to alleviate public concern, we will be undertaking a communication program to provide assurance and factual updates, but we will still likely see some activity from the lunatic fringe.

  “We won’t have seen the last of Apophis next year by any means. In fact, at about the same time that an impact in 2029 was ruled out, it started to look like that near miss might alter the orbit of the asteroid enough to cause a collision on its next pass in 2036. That too has long since been put to rest, as has a collision on subsequent passes out to the end of the century.

  “So, Mr. President, I hope this subject hasn’t taken more of your time than it merits given that it is very unlikely I’ll ever need to raise it with you again, but I thought you should be knowledgeable on the subject, since Apophis will inevitably stir up increased public interest. Now I’ll be off to fast-track your fresh water program.”

  “Eli, once again I have found our time together interesting and worthwhile. Let’s not call it my fresh water program though, let’s call it Larry’s program. When I go to meet with the president of MIT, I’d also like to meet with Larry himself. On the asteroid strike front, I am happy that the risk is so low that I won’t need to think about it again, but also happy to have a good grounding to be able to handle any questions on Apophis knowledgeably before steering them your way for more details. However, I haven’t missed the fact that you have carefully qualified your assurances with words like ‘very unlikely’ rather than ‘impossible,’ and that you would advise me promptly if this assessment were ever to change. So, I take it that it is something of an uncertain science?”

  “Mr. President, I had planned to have the MIT contingent come here to see you, but I am sure they would be most delighted by a visit from you; and yes, all science has its uncertainties. We have well-defined orbits for a large number of asteroids and comets of a size and orbit that could pose a hazard to Earth, just about all of them that we think are out there. However, there’s probably a small number we haven’t spotted yet, and a chance that one of those could be a problem. The bigger risk, however, is that the solar system is dynamic. The orbits of seemingly benign asteroids and short-period comets can change because of close encounters with one of the planets, especially Jupiter, or even because of minor collisions among themselves. Then there are the long-period comets we talked about. Those are ones with highly elliptical orbits extending many hundreds of millions of miles into the outer reaches of the solar system, and potentially coming toward us from any direction rather than the plane of the ecliptic, which is much easier to monitor. One of these could be headed toward us but not yet be close enough or fast enough for us to detect. So, we do need to keep an active look out in case something new develops.”

  Eli gathered up his materials and left the president musing to himself. Neither of them expected to meet again on matters of astronomy, other than to discuss public communications about Apophis, but they were wrong.

  Chapter 11

  November 1, 2027

  Canadian Rocky Mountains, near Golden, British Columbia

  Tom Svenson broke trail through about two feet of light snow covering the forest service road that led to the cabin. Beast, his 150-pound Tibetan Mastiff, followed behind, pulling a large toboggan loaded with a few basic supplies. Then, in sequence came Arthur, Susan and Sigrid, with Patricia Svenson bringing up the rear. There was room on the toboggan for seven-year-old Sigrid, and Beast could easily handle the additional weight, but the Svensons expected all three of their children to manage the three-mile uphill trek. All were equipped with lightweight metal frame snowshoes. The family was planning to spend the weekend at their mountain retreat.

  At an explosion of motion from just off the side of the road, Tom threw up his light shotgun and dropped a plump spruce grouse into the snow. Beast bolted ahead, toboggan and all, to gather up the bird and take joint credit for the kill. Grouse were fairly common in the area and, though not as great a prize as a wild turkey or a deer, were still something Tom would take for the pot when the opportunity arose. He thumbed another number 7½ shell into the breach of the 410-gauge Browning Citori over and under shotgun that he carried along for such purpose, being careful not to take it from the pocket holding the half dozen slugs. He’d brought the slugs just in case they encountered an aggressive cougar or wolf. Although it was unlikely they would see one, especially with Beast as part of the group, Tom preferred to be prepared, especially when the safety of his family was involved.

  They reached the cabin with plenty of light still left in the day, even though dark would fall by about four thirty at this time of year. Trish got to work setting a fire in the Franklin stove that sat in the middle of the cabin between the small living room and kitchen. With a relatively small area to heat, the woodburning stove would take little more than an hour to raise the temperature inside the cabin from twenty degrees up to a comfortable seventy degrees Fahrenheit, even as the outside temperature began to fall toward an overnight low of fifteen degrees or less. If anything, the trick was not to feed too much wood into the stove and overheat the little cabin, especially the second-floor loft where the two girls would sleep. Even in midwinter, when overnight temperatures could fall to minus thirty degrees Fahrenheit, it was easy to keep the cabin at a comfortable temperature with one early morning restoking.

  Tom, accompanied by eleven-year-old Arthur, got to work turning on the propane system they used for cooking and lighting, as well as refrigeration in the summer — there was no electric power in the area. Next, the two of them shoveled a clear path from the back door to the outhouse and then headed down to the lake with their ice auger. The hole in the four inches of ice would be their source of water, which they would haul back up to the cabin in pails. It would also serve for ice fishing the next day. In summertime Tom would use a small pump to pump water from the lake up to a large barrel on the front deck, but it would freeze solid at this time of the year.

  Tom could install a small generator to p
rovide power to the little mountain retreat, but he never would. The disruption to the peace and quiet of the lake would far outweigh the benefit. Tom and Trish were perfectly happy with the off-the-grid aspect of their cabin — no cell phone coverage, no electricity, no running water, hot or cold. Most of the small number of other cottage owners on the lake felt the same. Tom’s one concession to convenience was the propane system. He used fifty-pound refillable cylinders, about twice the height of a standard barbecue tank but still easy to move around. One tank would last most of a year, and he kept two full ones in reserve, topping up the empty one in the summer when he could drive the Suburban all the way in.

  Apart from that, Tom enjoyed cutting wood for heating and the occasional bonfire when the risk of forest fires was low enough to permit it. The area immediately around the lake was first-growth Douglas fir, never having been logged, though there were numerous logging concessions not far away. Tom never had to cut a tree down because there were ample deadfalls on his five-acre lot, which he tried to keep up with. He just needed to cut them up with a chainsaw and then split them to size with a splitting axe, or wedge and sledgehammer, depending on thickness. His current project was to cut up a forty-inch diameter giant, which put his forty-one–inch bar Stihl chainsaw to good use. The branches of the giant were a good workout for his twenty-four–inch bar chainsaw. In reality Tom had more wood split and stacked in his woodshed and under the upper deck of his bunkie than he could expect to burn in a decade. He also had most of a year’s supply stacked in the basement storage area of the cabin. He could have left off further cutting for a long time, but Tom liked to cut and split wood.