To Grasp the Heavens

Discussion in 'Alternate History Discussion: After 1900' started by sts-200, Aug 20, 2017.

  1. Shevek23 Spherical Cow-poke

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    Nightmarish! It is not possible, as the Mars surface team's deadline to launch approaches to know for sure that the diversion of the warship is even necessary--that the comet will come close enough to Earth for significant damage to result, let alone hit it full on, is not a certainty.

    As I understand it comets are more unpredictable than most cosmic objects in that they are outgassing sporadically, in effect the gases form half-assed thruster pulses changing the orbit at random. So, even if we had uncanny perfect data on its current trajectory and the ability to compute a Newtonian, heck even to factor in relativistic effects, with great precision, all that gives us is a probability fan, and a significant part of that will intersect Earth.

    Also, comets "calve." They don't come in one solid chunk; they split into a cluster of loosely affiliated separate gravel filled snowballs. That's why I mention a penumbra of partial encounter surrounding the prospect of the center of mass hitting square in the middle. Below a certain size fragments will burn up in the atmosphere, but this thing is coming in at the maximum plausible speed--there is little time for the material to disperse even if it all gets vaporized to plasma--the relatively dense mass of plasma can punch through almost like it were solid and deposit the majority of its energy on the surface. (And of course energy released in the atmosphere, and even chemical consequences of enough material vaporizing, even if high up, can do a lot of ruining of days. But this will be a footnote versus the impact damage to the surface unless the mass were quite dispersed indeed! It isn't that loose!)

    So--there can be no knowing whether the thing will fortunately veer and pass far enough away that the loose material that does encounter the atmosphere will all be small stuff. Maybe it won't veer quite that far and only a fraction of its material hits, and that will be dozens to hundreds of impacts scattered around the globe that do a lot of damage on the scale of say WWII-to WWIII, somewhere in there. The stuff is presumably not being aimed so up to a certain point, diverting massive effort to making shelters, to ride out the period of shockwaves and terrible weather and stockpile enough food plus warehousing tools and hardware and raw materials for reconstruction, evacuating coastlines to withdraw from inevitable tsunamis (not really technically tsunamis, having a different cause and detailed behavior, but anyway big waves, OK?) Stuff like that. Obviously if food is going to be stockpiled the question comes up just how hand to mouth the human species is right now and whether we are talking about leaving the majority of humanity to inevitable starvation, versus the prospect there might be enough and new crops coming in fast enough despite wonky weather.

    Or the comet could veer to come in straight on--a certain percentage of its mass will be scattered stuff hitting all around the globe; equally loose but densely packed masses will in effect strike as one thing, hundreds of technically separate impact craters being pretty much continuous and indeed overlapping in the center.

    So--perhaps the fact that the combined astronomical resources of humanity will only be able to plot the Newtonian path of an idealized single object with only limited precision is of no consequence because the expected uncertainty of its path due to randomly maneuvering itself with outgassing in spurts overwhelms observation uncertainty. In that case the calculation, not of its sure course but determining the probability fan, is indeed as refined as humans not gifted with the gift of mystic prophecy can get it, not because of our low tech but because the object is inherently unpredictable. In that case, it could be known within weeks of initial observation just how closely aimed the core of the effective shotgun blast is at Earth. The ability to gently nudge the thing, as far out from the Sun as possible, might be enough to move it so that the core of the probability fan is far enough from Earth that we can anticipate limited damage from peripheral stuff. The terrible thing is, if observation and calculation showed Earth is currently dead center on its most probable core path, moving it might be futile, and yet worth trying to do in the slim chance that it gets pushed enough and then by good fortune gets pushed further out of the way by its own behavior in sunlight. Vice versa if calculation showed that it would most likely bypass Earth with only a one in ten let us say chance of civilization wrecking damage, still that one chance in ten might come up and then it would have made a difference if the ship had tried to do what it could to move it--or the difference it manages to make could be that between a mass extinction event assuring extinction of our species versus a somewhat tangential and partial hammering that kills 90 percent of humanity but leaves survivors, or again between that and a lower intensity grazing that merely hurts us like ten world wars all at once.

    So it could be that if the Mars mission simply sticks to flight plan and comes home, everything would be fine. Then plans to send it comet chasing are a pointless death sentence. Or it could be humanity is doomed and everything is futile. But there simply can be no knowing, and the chance that they might accomplish something really significant in terms of human survival is high enough that they have to be asked to doom themselves trying.

    In this context the decision of the lander crew to refrain from burdening the ship crew and stretch their options is quite noble, and there really is no alternative--they are doomed never to reach Earth either way, as are the crew they abstain from rejoining--arguably they do them no favors adding weeks of extra endurance with the same end still inevitably claiming them, but if those weeks are weeks enabling them to come up with a comet-kicking plan and implement it, versus everyone starving or choking in excess CO2 or whatever gets them first before they can reach the comet, or anyway set up automated sequences designed to optimize their comet-pushing punch with the dead mass of their starved bodies adding to the inertia, then staying down might be crucial to saving the species.
     
  2. sts-200 Well-Known Member

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    Well, when you have to go, exploring your own new planet isn't a bad way to do it...
     
  3. sts-200 Well-Known Member

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    -Absolutely, due to various factors there wouldn’t be absolute certainty of the nucleus hitting until days before impact, and by then it’s too late for realistic deflection. To some degree they are only going to ever be acting on “best guesses”, with maybe a few observations possible along the way. So, they have to do what they can, and assume the worst.
    -Right, even if it is going to just about miss Earth, tidal gravity or other forces might cause it to break up, sending fragments onto a collision course. This is 1997, so they don’t know quite as much about the structure of comets as we do here and now. They should have seen Shoemaker-Levy 9, which caused Earth-sized disruptions on Jupiter, and “the comet” is bigger and faster than that. They have improving data on likely trajectories, but they still don’t really know much about the size, shape and structure.

    But it’s all going to be OK, Victorious is going to deflect the comet … isn’t it?
    Of course it is, and we are all working together to keep going and build more defences, so let’s keep quiet and get on with it. [replies nice, friendly officer, while surreptitiously unclipping his holster].
    -At this stage it’s Russian roulette with Teraton-class weapons. If the nucleus hits, I suspect it’s all over, the thing is about 4-8 times as energetic as what may have killed the dinosaurs.
    Given that something can be done to avoid total catastrophe (or if the nucleus isn’t on a collision course anyway), the size and distribution of any ejected material would be crucial. Due to solar radiation pressure, outgassing etc… the likely areas of impact wouldn’t be known for some time.
    City-block size chunks are still country-killers, and even bits that are only marginally detectable until they are close are going to be in the tens-low hundreds of kilotons (although there we are into the realm of atmospheric bursts and breakup).
    Even the “small stuff” isn’t quite as trivial as some of it might seem. A car-sized lump can easily have an energy equivalent of a couple of kilotons, although at that level, it will probably explode at high altitude. The dust will be pretty, although if there’s enough of it…

    They’ve nine months and most of a northern hemisphere growing season to prepare. As you say, local damage is probably going to be random (or only predictable a day or two in advance), preparations have to be about general survival, rescue and rebuilding. Or at least that is what I suspect people would be told; in practice, in a lot of places it couldn’t be anything other than survival of the fittest if damage is sufficiently widespread.
    I’m glad someone else is iffy about the use of “Tsunamis” – I debated the use of the word, and it doesn’t quite fit. I much prefer the old, imprecise term “tidal wave” anyway
    (and I like the phrase “wonky weather” too, it’s a very appealing use of language).
    - Determining an accurate orbit for any object isn’t something that can be done in a short time from Earth, even if it is in a stable orbit. That’s why I made such a fuss about early amateur observations, which would allow for a range of possible trajectories to be run backwards and matched up. Equally important would be the observations from Mars, which would give them a giant stereoscopic effect. Looking just from Earth, all you can do is plot 2-D position and then (maybe) use radar to determine the range and 1-D speed (range rate). From that, they can determine velocity and therefore orbit over time (ideally a few months). With the exception of the radar range (once they can get a clear return), none of those individual measurements will be very accurate. By viewing it from two angles they can plot positions in 3-D directly, and cross-check one measurement against others, so the whole thing can happen more quickly. Even if all the bombs are duds, the Mars ship has provided this immeasurably valuable data.


    The ongoing ability to track from both Earth and the ship while they are on their way out to intercept will continue the process. Barring errors, uncertainties can be smoothed out in time, as the comet has to pass through all of the known (but slightly uncertain) locations. As it closes on the sun, quite possibly the outgassing activity will increase, but they will still be closely tracking it and will have a very good idea of what orbit it started on, so they can monitor the rate of changes and try (hopefully) to predict where the thing will end up.
    -“Something must be done, this is something, therefore we must do it.”
    For once, the logic of that entertaining warning holds true. The decision to send the Mars ship was made almost immediately it was realised that it was possible. Their best estimates show a real chance of an impact, and the ship has the means to do something. They planned to leave for Earth on the 31st May, and the launch window for the Venus swingby closes a few days later, so waiting in Mars orbit is not an option.
    They might be throwing away their lives, although as I say their ability to track the comet from a unique vantage point is of definite value. Even if they only reduce the amount/chance of impacts, their mission is worthwhile.
    If it is found that there is no possibility of impact, their “attack” can be called off at any time up to a few hours before interception. There may be no threat, or the bombs might not work, or they may not have much effect. There could even be a worst-case scenario where the attack goes totally wrong and increases the chance of impact.
    We shall see…

    -That’s what they thought too, and it doesn’t sound like a bad way to spend your final days, exploring your own planet.
    In some ways it’s worse than that for the surviving crew. They can last a long time. It would have taken them over ten months to get home, while they can reach the comet in slightly under five.
    On the other hand, they’ll see the results of their efforts, and can certainly live long enough to find out what happens to Earth.
    More practically, they can continue to make observations and plot trajectories long after interception.
     
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  4. sts-200 Well-Known Member

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    Strike from the Depths

    The OGM-91 missile was a Lockheed project that started in 1987, following the decision to go ahead with the construction of an orbital deterrent system. At first, it was intended that the missile be used by both American deterrent platforms and the British V-Ships. However, shortly after development started, the design was changed to focus entirely on deep space deployment as the US Administration pursued the deployment of an American counterpart to the V-Ships. The START treaty and the collapse of the Soviet Union later conspired to stop that, but by that time the development of the missile was sufficiently advanced that the Americans agreed to complete it for use on the British ships. This left Britain in a tricky situation; the US had agreed to continue leading and part-funding the development of the missiles, but there was no longer the same urgency or willingness to foot the bill for a highly complex weapon that would probably never enter service with US forces.

    As originally designed, missile had a range of sophisticated features. It would be able to self-guide towards its targets, and accept target and guidance updates using a complex code system from its launching ship. The missiles could boost themselves directly towards Earth, or perform a "coast-sprint"; flying gently towards the target before accelerating as they approached the atmosphere. Time-on-target attacks on single sites could be made using multiple RV entry vectors, or the warheads could be scattered across half the planet. There was room for electronic jammers and a variety of decoys, as well as the capability for high-altitude jamming bursts by a single warhead to give the others a higher chance of penetrating enemy defences.

    None of that capability was easy or cheap, and by 1991 the project was both over budget and behind schedule. Faced with obvious American reluctance to throw additional resources at the program, late that year the MoD agreed to the development of a simpler version, which would still be adequate for Britain's needs. That design would be designated OGM-91B.
    The capabilities of the missiles were reduced, and the requirement to carry up to 18 of the ultra-compact US-designed warheads was dropped. Several operational modes (including "coast-sprint") were removed, research into active IR and passive radar detection countermeasures was cut back, and the propulsion systems were simplified. The revised missile would share some hardware with Lockheed's new Trident D5, a move that both cut costs and helped to keep the US actively involved in the program.

    Known as the "Kraken" in British service, OGM-91B’s relationship with the US Navy’s Trident submarine-based rocket was more than skin-deep. The missile's solid-fuel motor is a derivative of the Trident upper stage adapted for long-term storage in space, and many of the electronic systems and control hardware are directly related. However, when fired from deep space, Kraken will have to operate for much longer periods of time than Trident, and its guidance and power systems are therefore much more capable.
    The British-built warheads were co-developed with the Americans, and are to be fitted into US-designed re-entry vehicles (RVs), with each warhead expected to deliver a yield of 1.2Mt. The RVs themselves are unusually long, and are designed to enter Earth's atmosphere at speeds of up to 12km/s, and on much steeper trajectories than are typical for ICBMs. If they ever had to be launched against their targets on Earth, it could be at ranges beyond quarter of a million miles. Highly accurate launch parameters from the V-Ship would be supplemented by an automatic stellar-inertial system with a GPS overlay (on the chance that GPS was still working during their descent). Several times during flight, and before MIRVing, the warhead bus will check its position using the stars, the Moon and the Earth's horizon. The RVs are believed to incorporate "stealth" features, and there are known to be a variety of decoy mechanisms fitted. Unlike some of the latest Earth-based systems, the RVs themselves are not guided, as the extreme re-entry environment had been found to make this a mass and cost prohibitive development. Each RV carries a doppler radar-altimeter, a basic inertial measurement unit and a timer, any of which can be used to trigger the warhead.
    Unlike an ICBM, the Kraken is not a multi-stage rocket capable of great velocity changes, as all it is required to do is decelerate out of high Earth orbit and fall towards the planet. Mid-course correction and MIRVing requirements are conducted over much longer periods, but require only a slightly greater delta-V capability than on a normal ballistic missile.

    At just over 54.1km/s, or 121,000 mph, Victorious' interception of the comet would be far faster than anything for which the missiles were designed; in fact, it would be faster than any flyby manoeuvre ever attempted before. It had been hard to leave their crewmates behind on Mars, but their mission was one of unparalleled importance, and they had all trained for far worse. Although it had been glossed over and lost in the hype and glamour of the “International Mars Mission”, they were all military men who had trained to use their weapons to kill millions of people. In a few days’ time, they would instead be using them in an attempt to save billions.

    In the four months since their last contact with Mars, all four of them had become accustomed to the tasks of taking star fixes, checking tracking cameras, zeroing, comparing and re-zeroing their inertial navigation units and planning for the days ahead.
    On the way out to the comet, sights and tracking updates had been made almost continuously, defining the trajectory of both the comet and the Victorious with as much precision as is possible. The current path of the comet is now known with far greater precision than in May, and it is still possible that it might just skim past the Earth’s atmosphere on the 1st March 1998. However, that margin is slim, and the balance of probability is that it will hit the planet’s limb. If the comet had been projected to miss by a few thousand kilometres, their interception mission might have been called off, as in those circumstances doing nothing might be safer than risking the consequences of an error.

    Over the next 36 hours, the Mars Orbital Camera on the ship’s keel provides a final piece of information to the planners. As the ship closes in on the comet, the camera is finally able to show details of its shape, which not even the most powerful telescope on Earth could do directly. Extremely precise timing would be needed to ensure that the warheads would near-miss a target that was now known to be a rather uneven potato-shaped body, with maximum and minimum diameters of 13.5 and 10.2km. The best ideas (and that’s all they are) suggest that the warheads should explode as close to the surface as possible, but they must not hit. Knowing the details of the topography has allowed the timings to be modified by a tiny fraction of a second, meaning the bombs should detonate slightly closer to the comet, hopefully vaporising and ejecting more material and pushing it further away from its course towards Earth.

    With everything at stake, the overall interception plan has been designed to minimise the risks of error or failure, and so the missiles will be called on to do as little as possible. To eliminate the risk of missile malfunctions altogether, there had been a proposal that Victorious herself be targeted directly at the comet (she would actually have been vaporised by detonations a few milliseconds before impact). However, in addition to condemning the crew to a bang so big they would never hear it, ramming could never have produced the desired effect, as detonating more than one warhead required that there be some distance between them.
    The plan that they will now execute requires exquisite precision. Some of the velocities need to be correct to within a few millimetres per second, and the timings to within milliseconds.

    Catches release and strong springs rip the protective MLI blankets clear, revealing the missiles and their rings of stiletto-like re-entry vehicles. Appropriately enough, given its intended purpose, Kraken is an evil-looking weapon, with these ten vicious points silently waiting to stab at their targets.

    “Commit settings”

    “Guidance checksum playbacks OK”

    “Warheads one through ten Arm”

    “Sixty seconds”

    “All Arming lights green”

    “Lock”

    “Locked”

    “Pyro arm”

    “Pyros armed”

    “Launch keys to Launch on my mark”
    “…”
    “Two, One, Mark”
    “…”
    “Launch Commit”

    With that command, David Lutterell presses the one button on the ship that no-one ever wanted to push, for real, until now. Flipping up the plastic cover, the square red launch button is satisfyingly marked “FIRE”. What happens next is strangely unsatisfying; there is scarcely any sound, no roar of rockets or thunderous explosion of Cordite, just a dull thump and a slight vibration in the ship’s hull.

    Pyrotechnic squibs push Kraken-2 away from the side of the ship, taking with it more destructive power than has been used in all the wars mankind has ever fought.

    This missile carries the second set of warheads that will reach the comet, although it is the first to be launched. Six hours before closest approach, the rocket is being fired in a relatively normal manner. Ninety seconds after the squibs push it away from the side of the ship, the RCS jets come to life, and the main motor fires to throw the missile back down Victorious' flight path. Five minutes after launch, the RV deployment sequence begins. There are no complicated MIRVing manoeuvres, and all the warhead carrier is programmed to do is point itself in five different directions and release a pair of warheads. The RV deployment springs will do the rest, pushing the ten bombs out in a decagonal pattern.
    By the time these warheads reach the comet, it will be nine minutes after the first set of detonations, long enough for radiation effects to diminish and (it is hoped) for some of the debris to disperse. Detonating the two sets together would have been ideal, but there was no way of doing that without requiring both missiles to make complex course changes.

    The presence of debris and the chance that the missile itself might malfunction makes it less likely that this second strike will succeed. The plan calls for the first set of explosions to occur with as great a level of certainty as possible.

    The first set of warheads to hit the comet will not even be fired in the traditional sense. To ensure that V-Ships have as many strike options as possible, the Kraken missiles could be commanded from on board the ship to dispense their warheads directly, without being launched. Originally, this was intended as a backup system to allow the ships to deploy the RVs of any malfunctioning weapons by steering the entire ship towards Earth and releasing them directly onto an impact trajectory. Now, the system will be used to ensure that the first set of warheads are deployed with a minimum of risk and with the maximum level of accuracy.
    Thanks to weeks of on-board and ground-based navigation updates that have been cross-checked with each other, Victorious’ computers know the ship’s position to within a few hundred feet, and her velocity to within about a millimetre per second. One of the largest remaining sources of error in her position is due to uncertainty as to the exact location of the Earth itself, as well as that of the ground stations that play a role in tracking the ship.
    The Kraken missiles cannot achieve this level of accuracy, as their sensors cannot reference the Earth and Lunar limbs, and they are equipped with far less sophisticated navigation and sensor systems than those on Earth and the Victorious. Not firing the missile in the traditional sense also removes the risk of malfunction within its numerous control systems or in the rocket motor itself.

    This first strike is the best chance to remove the threat of the comet, and nothing can be allowed to go wrong.

    _______


    Radio beams reach out and are scattered back from a vast area ahead, until the right signal is received at the right time to release the first burst of energy. Some of mankind's most ingeniously concocted compounds do their job, focussing a wave of pressure that defies the imagination. Even so, these incomprehensible forces are only being used to start more fundamental processes. A small, curiously-shaped lump of silver-grey metal is on the receiving end of the blast. Just as it is squashed by a shockwave that would have flattened most buildings, the first blizzard of particles arrives from outside, their fundamental nature allowing many of them to zip through what seemed like solid matter. Heat and light output multiply exponentially, flashing out, before being momentarily contained while they vaporise the outer layers of another chunk of metal, creating an impulse that squashes it with forces nearly a million times greater than anything encountered so far. Less than half a microsecond later, a soup of light elements is already vastly hotter than the core of the sun, when it is hit by a new shockwave of radiation emitted by the squashed metal at the centre. Temperatures multiply by ten, and the process that powers the observable universe begins, emitting unimaginable numbers of particles into the surrounding materials. Despite the immense pressures, nothing could now stop the expansion, but for a few brief nanoseconds, the multiplication rate would outrun even this. As the reaction wave peaks, the material now heated not just by the initial events and the central core but also by the early effects of the burn itself, energy output reaches levels that defy superlatives. For nearly a nanosecond, mankind's brilliance competes with the sun.

    Aboard Victorious, no-one saw those first ten warheads explode; at that moment, the ship is 14,700km away, and the crew are safely inside their solar flare shelter. At such a distance they should be in no danger, but if anything went wrong, the shelter would shield them from the effects of the intense radiation that is blasting out unchecked into the vacuum of space.
    None of the crew saw the second Kraken missile's warheads go off either; by then, they were on the far side of the comet. They knew something had happened though, as they could see the flash that illuminated the vast cloud of dust kicked out by the first explosions, reflecting off it to produce a spectacular expanding halo of light.

    It would take the light of the flashes almost nineteen minutes to reach Earth, but detailed observations of the effects began long before that. Twenty seconds after the first set of explosions, the camera on Victorious’ keel swings around and starts to take pictures of the comet.

    These first few images will provide important clues for the world’s space scientists, who are rushing to identify what, if anything, has been achieved.
     
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  5. Shevek23 Spherical Cow-poke

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    You are reminding me how much you enjoy writing suspense.
     
  6. sts-200 Well-Known Member

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    I do love a good cliffhanger.

    Those of you with very long memories might have noticed that it is now fifteen years later, and we have caught up with the opening of the story.
     
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  7. RanulfC Well-Known Member

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    And the Prologue begins to become clear.....

    Randy
     
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  8. Julius Vogel A rascal's rascal

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    Oh yes
     
  9. Shevek23 Spherical Cow-poke

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    Oh bloody hell. I had forgotten about that.
     
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  10. cosimas Member

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    Jan 28, 2016
    This is rather good. And rather tense right now...
     
  11. sts-200 Well-Known Member

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    Glad you are enjoying it so far.

    It's fair to say they're not in for a relaxing few months.
     
  12. sts-200 Well-Known Member

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    The Good News, and the Bad News

    Energy reflected its way down the tunnel, some of it at light speed, some at mere millions of miles an hour. Crystals that might have formed before life even started on Earth flashed to gas, filling the vacuum of space with superheated steam and particles of rock. Those gasses were under pressure, and that pressure wanted to get out. Some of it burst back out the way the energy had come in, turning the tunnel into a giant rocket motor. Unlike most rocket motors, this one wasn’t very well built, and its walls started to burst under the sudden pressure. Plumes of soot, chunks of ice and condensing gases turned the surroundings into something resembling a blizzard and a sandstorm put together, while the solid objects that had made up the tunnel walls didn’t seem to be moving.
    But they were.

    As the explosions were detected back on Earth, late in the evening of Sunday the 19th October, there was worldwide relief, although little in the way of celebration.

    By this time, even the most liberal governments were becoming well practised in the art of controlling the distribution of new information, and most nations had adopted an active policy of stopping and denying rumours. Naturally, the methods by which rumours were stopped varied considerably. With such a worldwide focus on the unfolding “events” in space (news media never referred to it as a “crisis” or “emergency”), the latest projection, guess or rumour could spread very quickly, and so there was little chance that any blatant propaganda or concealment would remain unquestioned for long. Once the global sense of shock started to wear off there had been some nasty incidents, but by and large, those people who understood at all could see that they were in this together. There was nowhere to flee to.
    Whole populations had to deal with real changes to their lives, as rationing began to affect their food, mobility and healthcare. Disruption at the local level could be much more extreme, as there were new depots, infrastructure and storage facilities being built everywhere. Freedoms were being curtailed too; property rights, free speech, and the right to protest were being suspended, ignored, or circumvented almost everywhere.

    The level of patience and acceptance seen so far was not something that could be abused, and there had to be a bit of give and take on both sides. Censorship or “controlled information” was widely understood to be a necessity, but it was both right and healthy that the public soon found other ways to express their opinions. Among these was the “ironic protest”, which was intended to draw attention, before its leaders made a point that was usually unrelated to the (frequently absurd) nature of the protest. One of the most famous of these was held in London’s Docklands on 21st September, as thousands of people marched through the financial district, carrying flags and banners with the logos of the likes of CND and Greenpeace, all the while enthusiastically chanting “More Nukes, More Nukes, More Nukes!”. As one of the first such incidents, all the authorities could see was the start of a major act of public disorder, and they prepared to react swiftly and extensively. Armed riot police were on the verge of moving in, before the incident commander saw what was going on, and laughed. Humour had saved the day.

    The distribution and content of news reports was a more serious matter, and lessons could be learned from history’s most successful propagandists and story-peddlers; a good piece of controlled information has at least some underlying truth to it. After a slightly shaky start, great efforts had been made to assure the public that they were not being lied to, and it had been decided early on (at least in the West) that if there was bad news, people would be told.
    However, the policy on information was still one of controlled release, coupled with the dark arts of spin, simplification and of directing people’s attention in the right direction, at the right time.

    With such an all-important event as the interception, there would be a limit as to how far these methods could be pushed; everyone would want answers. Consequently, the tactics had shifted towards managing expectations; there could be no immediate announcement, it would be several days before the full results were known. No-one talked about “failure”, but they did keep mentioning the “next line of defence”; this is not mankind’s one and only chance, as anything that might slip through can be intercepted later.

    It didn’t help to calm nerves, but scientists had warned that the amount of debris that would likely be blasted out by the explosions would make it impossible for anyone to plot the position of the comet for some time, probably at least a day. Even then, a series of several days’ observations would be needed to measure and confirm any change in its path. Those who advocated claiming success with a day or two had been overruled; public trust would be irretrievably destroyed if anyone even suspected such deception, and public trust might be badly needed in the weeks to come.

    As was expected, observations from around the world provided little information in the hours after the blasts. Radio telescopes could provide only limited data on such a diffuse and distant target, while the best in optical astronomy, including the newly commissioned Keck Observatory and NASA's orbiting Hubble and Galileo telescopes were unable to see more than a fuzzy ball of light. Clearly, something had been achieved; vast amounts of debris had been ejected, but this was so dense and reflective that it shrouded the nucleus, and meant that there was no immediate prospect of identifying the tiny change in trajectory that would make all the difference.
    Meanwhile, spectroscopic observations show that the debris contains a higher proportion of dust, and less water and other ices than was expected, data that may prove useful in developing theories of comet formation, and to help in identifying the makeup of the outer solar system. While these discoveries are scientifically interesting, they are not the vital velocity data that everyone is waiting for.

    By Tuesday evening, relief is beginning to turn into cold fear, as there are still no positive updates. Space Agencies are reported to be “studying the latest images”, “analysing data”, “projecting trajectory probabilities” and other similarly vague phrases. Even though it had been repeatedly explained that it would take a few days for any sort of conclusive data to come out, by Wednesday nerves were beginning to show. Public updates were merely repeating the information and language used in earlier briefings.
    Amateur observers could offer little that was of use; who knew if their observations were accurate? If they appeared in the paper or on the internet, who knew if they were censored?
    In any case, all their pictures showed was a dimly glowing blob.

    By and large, both public order and morale had held up until now, thanks to regular updates and a swift but firm grasp on vital materials; for instance, across most of the world, laws against stockpiling food and fuel had been introduced, and had been tightened in the days leading up to the interception. International exchanges and markets had been operating under restrictions for months, and stock exchanges were now closed for at least a week. Numerous commodities were still being traded, but usually at fixed prices, and in quantities that must not be far from the expected, pre-comet trends. These measures had helped to keep trade and society running with some semblance of normality, and wider public trust in “the authorities” was still holding up. In many places, there were echoes of a wartime spirit; everyone needs to avoid defeatism, to help out, to be ready to spring into action. That may not always be the right action, but doing something is better than doing nothing, and doing anything is better than complaining.

    Nevertheless, by the morning of Thursday the 23rd, cracks were starting to show, as around the world the balance of opinion began to tip towards the belief that no news must mean bad news.

    At the highest levels, they were worried too, but by now, their worries were better informed.

    “… there was always a chance of this, we just didn't know how big a chance.”

    “So, instead of one huge impact, there'll be lots of them … you've wasted five months reaching out to punch the face of God, and he's shown us where our hubris takes…”

    “Why don't you go and bother your God somewhere else, actually why the fu...”

    “SHUTUP both of you.”

    “I'm sorry sir, I…”

    “SHUTUP!!! … hahhh … NOW … Gentlemen, let's just slow down a minute, Ahh, I think we need a fresh voice here. Doctor Krantz?”

    “Right. As Dr Jorgensen was saying, the first set of warheads must have detonated very close to the surface, and the structure of the comet did the rest. We aimed to vaporise one part of the surface, turning it into a crater, with the debris acting as a sort-of rocket motor that would push the entire nucleus in one direction. Instead, the blast, or rather the flash, must have turned voids inside the comet into pressure-bombs, and that’s what blew the comet apart. Even so, err … actually, we’ve been lucky. Our analysis shows the bombs must have exploded right at the surface – we don’t see how this could have happened otherwise – a couple of milliseconds later and they might have hit it and been destroyed before they could explode.

    Our best doppler radar measurements suggest the fragments will never come back together again, and that’s quite possible; we hit it with more than the nucleus’ gravitational binding energy. Fundamentally, we don't know what the interior of a comet is like, and it looks like this one may well have been several different bodies that came together over time. The bombs from the second Kraken would have entered the debris long before they detonated, and we can only confirm that five, or maybe six of them went off. They might have accelerated the breakup, but at this stage that’s a good thing.

    What we have is a shell, like a football … actually more like a deflated football … of material expanding outwards in all directions. Our best data shows that the group velocity of that material has changed very slightly, but that's almost irrelevant. By the time it reaches Earth, the dust cloud will be about 300,000km across, however the larger pieces - the ones that are dangerous - will be confined into more like 60,000km. The good news is that the four largest bits look like they're going to miss us, but there are huge numbers of smaller objects that will still hit.
    Ah, yeah … When I say small, I mean stuff from the size of houses up to the size of a city block. We've not wasted time. I'd say we've been 99% successful - we were possibly going to be hit by the entire comet, now it's certainly down to less than 1%.”

    “Our best models suggest more like 0.5% in terms of mass. It's a success, we've saved the human race. But we have a lot more to do.”

    “You say models? Not real data?”

    “I just remind everyone, we don’t have much more time to come up with an announcement…”

    “Yes, we know. Carry on…”

    “Sophisticated models based on fundamental physics, our theories have come a long way in the last four months, but yes, the data is still in the early stages. We’re doing all we can, all the major observatories are on it. We think one of the larger fragments has about a 10% chance of impact, so we need to prepare to hit that again, but we also need to focus on the smaller chunks.
    We’ve split the debris into classes. “A” are the five big fragments, one of which needs dealing with.

    B-class fragments are rocks, or rather objects, that are 20m and up. The largest we know of so far is about 150m across, the smaller ones we can't directly detect yet, but the we are confident of several hundred 50-100m objects. At the low end these are the smallest objects we will be able to plot accurately once they’re a few million kilometres out. In other words, these are the smallest fragments that we can plan to intercept in deep space.
    And at the low end too, if it’s a sort of dusty snow or ice, it probably won't reach the ground, but we now know the comet contains a significant amount of rocky material and maybe some higher density ices, which could make it to the surface.

    C-class are the smaller ones we can't do much about. Some of those will reach the surface, but we’re down to local damage. Most of what comes from them will be small rocks and ices that have decelerated before they reach the ground – so we’re talking damage to roofs, maybe little craters … not major impact blasts.

    D-class is everything under a few feet across. That stuff won’t reach us, it’ll...”

    “OK, we’ve had this briefing before. What’s new. Where’s the threat and what do we do about it?”

    “It’s the B-class that are the threat. These are 50-200m objects with energies equivalent to between 20 and 500 Megatons; they'll all reach the surface and cause significant damage. There are likely to be about a hundred or so of these still on course for Earth, and statistical models suggest a few hundred more at lower…”

    “A hundred, five-hundred-Megaton explosions? Plus hundreds more low-yield stuff? You call that saving the human race - that's, that's … worse than global nuclear war.”

    “A hundred in the range 20-500 Megatons, plus about 200-300 more in the range 200 Kilotons to 20 Megatons.”

    “yeah, but…”

    “AND THOSE big ones are the objects we can still do something about.
    Maybe using the word Megatons is bad idea. These will not be nuclear explosions, there'll be no fallout, and even the shock pattern will be different. A lot of the damage will be from flash - that's heat radiated from the fireball, either in the sky or on the ground.
    As I say, we have a lot more to do, but we still have time to deflect or disrupt most of these fragments.”

    “Our interceptor programs have been running since day one, and we have several workable systems that are being prepared. The Russians and Europeans have stuff in the works too. Alongside that, we’re working on targeting data; that’s almost a bigger challenge, we need to know where and when.”

    “There's one more bit of news, it’s good and bad; we have a more accurate projection of impact time. The centre of the event will be at 19:30UTC, plus-or-minus an hour on March 1st, and the Earth will path through the zone with these larger objects in about 15 minutes. That means only one side of the planet will be hit, centred on somewhere over the south Pacific, north of New Zealand. That means South America, Europe and Africa are safe, but all of Asia and Oceania is in the impact zone. Most of the US is safe, except Hawaii and a chance of something on the West coast. The timing’s uncertain there.”

    “Ohh God … We’ll need to … That projection goes no further for now … got it?”

    “Yes, Sir”

    “So, which of your interception concepts is going to work?”

    “We still have several options, the first…”

    “Sir, we’re out of time. Look…”

    “What’s this?”

    “CBS is about to go live. Someone’s talked. They’re calling it a partial success … they know they can’t…”

    “Stop the broadcast.”
     
    Last edited: Jan 18, 2018 at 2:40 PM
    Ato, Vatem, CrazyGeorge and 4 others like this.
  13. torten Well-Known Member

    Joined:
    Aug 1, 2014
    Location:
    UK
    Well, at least half the world is safe. Still, I wonder if Victorious can get home?
     
  14. Evan Life, Liberty, and Pursuit of Happiness!

    Joined:
    Oct 13, 2010
    Location:
    Quiet Resistance, People's Republic of Cascadia
    Possible tsunamis across the Pacific Ocean, perhaps even going into the Indian Ocean to impact India and Africa. And just how bad are they going to be? This could be horrible.
     
  15. RanulfC Well-Known Member

    Joined:
    Mar 11, 2014
    "Ice-cream Sunday, on Tuesday..."

    Randy
     
  16. sts-200 Well-Known Member

    Joined:
    Aug 6, 2010
    Location:
    UK
    "This is obviously some strange usage of the word "safe" that I wasn't previously aware of...":)

    One might be heading for a new ice age, the other is heading for the icy depths of space.
     
  17. sts-200 Well-Known Member

    Joined:
    Aug 6, 2010
    Location:
    UK
    Not much doubt about the Indian Ocean, but they still have just over four months to go.
     
  18. sts-200 Well-Known Member

    Joined:
    Aug 6, 2010
    Location:
    UK
    Eat, Drink and be Merry, for tomorrow we diet...
     
  19. Ato Chronic neo-nostalgia sufferer.

    Joined:
    Jan 10, 2011
    Location:
    Deira Free State
    Obviously what we need is a giant ring of railguns that will blast most of the debris out of the sky. Pprobably in a very geopolitically stable area like the middle east, where there will be no chance whatsoever of one regional power siezing control and using it to conquer thier neighbours,


    I think it's now time to admit that you are writing an Ace Combat-Real Life cross over fan fiction.
     
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  20. RanulfC Well-Known Member

    Joined:
    Mar 11, 2014
    "Lucifer's Hammer" :)

    Randy
     
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