Cfrgtkky

I'm writing a story to be set around the late 1980s or early 1990s. The story opens with a spaceship crashing to Earth, hitting and destroying a large part of central London. The idea is that, before the spaceship actually hits, it will be detected by a missile strike detection system and the operators will think that a nuclear missile has been fired at the U.K. The U.K. will then fire a retaliatory strike at Russia, thinking that they are responsible for the London strike, thus setting off the whole mutually-assured destruction thing and triggering a nuclear war that leads to the collapse of society.

My question is this: how would a nuclear strike have been detected in that era? And could a spaceship crashing (out of control, but travelling in a straight-downward direction) theoretically be detected on such a system? My plan at the moment is that the ship could have a radiological signature, to really convince the detection system's operators that they're looking at a genuine nuclear strike, and it will only be detected once it's entered Earth's orbit (so they won't have tracked it across the solar system or anything like that, and won't realise what the object they're tracking really is) but a better idea of how the real-world systems worked (or still work, if there has been no change) would really help.

My opening scene currently has a technician in a monitoring station picking up the ship on his equipment, and telephoning a superior officer to inform them but I'm not sure how accurate that is.

There have been several "close calls" in Soviet and US history regarding false detection of missile launches or strikes. The so-called "Great Storm" in 1967 is one example, sunlight reflecting off clouds in 1983 is another.

Detecting missile launches in late 1980s / early 1990s is extremely different than today - especially on the soviet side of the fence (the US was more forward-moving with computerized technology in the 80s/90s than the soviets, but the details of that are FAR too tedious to explain in answer to this question). The "old" (meaning pre-computerized) systems relied on radio transmissions, random bursts of light (ie explosions that resembled the bursts similar to that of rockets taking off), and so on. More advanced computerized systems came with more precise detection systems (and therefore less error rates), but these only came to the US in the early 1980s (with President Reagan's so-called "star wars" advancements), and to Russia in the mid 1990s.

So before the computerized advancements, the "crash" of a spaceship - if it caused a small or medium-sized explosion near a known US missile site - would almost certainly have triggered concern from the Russians as a nuclear launch.

Another option is an alien craft that, by nature of operation, would interfere with radio operations on either (or both) sides of the fence, much like the 1967 event. This is not far-fetched; a complex space-craft might send radio waves cross-galaxy in a way that requires such large amounts of energy it blasts through the noise floor of radio frequencies.

Yet another option is where the spaceship hits - if it hits a known target (like the White House, Congress, Supreme Court - or on the USSR side of the fence the Kremlin, Baku, etc) - might be wrongly perceived as an attack.

What kind of ICBM/missile tracking tech did they have in the 80s?

Sonic boom Missiles really haul the mail, and the sonic boom is fairly distinctive. With listening posts throughout the world/nation, it's possible to track the movement of the missile. With fast enough computers (a bit of a problem in the 80s), this could be used to extrapolate an actual position (sonic booms happen after the fact).

Heat Missiles are notorious polluters with all that rocket thrust to keep them going. Consequently, there's a boatload of heat. To be honest, there's heat all over. A house fire can produce more therms than the exhaust of a rocket, so we're back to computers doing things like analyzing the path and speed of the heat source. Fast + ballistic = bad. Stationary and sea-level = call the fire department.

Radar Missiles are small, but not that small. Radar can pick them so long as the radar system's refresh time is fast enough to capture their passing. Some radar installations in the 80s could do it, but most couldn't. Do you remember that lovely line that sweeps around 360° on the old WWII radar screens? That's the position of the rotating antenna that's emitting/detecting the radar signal. We don't draw the line anymore, but it's still there, and if it can't get around fast enough, it can't see the missile. (Note that phased array radar do this electronically along a narrow arc, which makes them fast. They're great for seeing what's in front of a plane, they're less useful for watching a horizon, but it's better than what it was.)

Visual In the end, machines make mistakes. Nothings more useful than a pair of eyes and a set of binoculars. Pro: more trustworthy identification. Con: You don't have long before... oh, cra... BOOM!

Radiation Finally, though unlikely to have been used regularly (or at all) during the 80s, the tech did exist to track radiation sources. Usually that's not an issue until after the missile has hit, but you could believably use it in a story (hey, if The Blacklist can suggest six Soviet briefcase nukes hidden in the U.S. in the 60s, then we Americans will suck down just about anything).

Could any or all of these be used to track a spaceship? Sure! The biggest problem would be the confusion over the fact that it's the wrong kind of ballistic path. It's a "fall from orbit" ballistic path rather than a "launched from my enemy's backyard" path. That'd confuse NORAD for a bit, but it's quite believable that they'd see it.

Yeah, but what about today?

I doubt any of this could be done in the 80s. I'd be mildly surprised of some of it could actually be done today. But for the sake of being thorough.

Light reflection Objects in the sky reflect/occlude light. It's one of the ways we detect new stars and planets — by looking for light that should be there, but isn't, or that shouldn't be there, but is.

EM emissions Anything that uses electronics emits EM noise. To a degree this can be blocked, but sometimes it can't. Add to this that thermal differentials, metallic stress, communications to/from/with the missile... all of this could be detected and triangulated.

Humidity AKA contrails, the condensation of water behind the high-heat/high-pressure-sudden-cold/low-pressure exhaust of a jet/rocket engine. Whether they're visible or not, the change in humidity is there, and when light passes through it, that light changes. (And if you can see it... see "Visual," above.)

There's an actually story from the Cuban Missile Crisis that nearly resulted in a false retaliation strike. Prior to the Crisis, Military thinking was that Soviet attacks would come over the Arctic and most stations in the United States faced the North Pole. Naturally, when missiles were discovered in Cuba, a lot of early warning systems were hastily pointed the other way, including one in New Jersey. During the 13 days of the Stand off, the newly southern facing center got news they really didn't want to recieve... there was a launch from the general Cuba area of a missile... or what looked like a missile until a few tense moments showed that it's course would take it too high and towards West Africa... as it turns out, the "missile" was actually a Rocket launched from Cape Canaveral... no one had told the egg-heads at NASA that now's not the time to be launching rockets... Just one of four events in the Cuba Missile Crisis that threatened to unleash all out nuclear war, but speaks a lot for your question.

Incidentally, during the Cold War, especially the 80s, it was believed that Soviet Missiles would expend a total of 4 minutes from launch to impact anywhere on the British Islands (Compared to United States, where this time was about a 30 minute window from Launch to Impact) so the British Second Strike (the retaliation, and under MAD, the defensive part of having nukes) was not thought to be an immediate response. Rather, their Nuclear Subs were required to check a series of automated signals. If they could not confirm the signals, they were to open the "Letters of Last Resort" and follow the instructions. These letters were written by the Prime Minister, sealed in envelopes and placed in safes in each of the 4 nuclear subs in the British Navy. These letters contained the final instructions of the British Government should the worst happen. Because the policy is to destroy all Letters of Last Resort after the end of a PM's Premiership, we do not know the specifics of the types of orders given, but speculation ranges from which cities to target for retaliation (presuming they still stand) to which nation to take future orders from.

The signal is assumed to have a number of redundancies both fore maintenance, breakages, and survival of some of British Government outside of London, so the destruction of London would likely not entail retaliation from the British.

Though depending on the year, the political situation would dramatically shift. One important thing to consider is November 1983, when the television film "The Day After" aired in the U.S. Although it admitted that the story was a very optimistic outlook on the challenges facing the United States after full scale Nuclear War, the film was grim enough to scare even Ronald Regan into rethinking Nuclear Policy and convinced him to de-escalate the situation. It combined with the U.S. Realization that the Able Archer '83 exercise had put the Soviet Union on such a high alert that it's considered the closest humanity ever came to an intentional Nuclear War that didn't involve Cuba for a one two punch to get the two sides talking. Though debatable about who sent the message, the film's producer, Nicholas Meyer, did get wind that the film had a great deal of influence behind the push for the INF Treaty of '88.

Because of this, the late 80s had a bit more cooperation with it than the early 80s and by George H.W. Bush's Presidency, relations with the Soviet Union had smoothed out. The U.S.S.R. collapsed on Christmas Day, 1992, rather peacefully, and the 90s era of the U.S.S.R. military was categorized by a lot of budget problems leading to a rather inefficient war machine. The threat of Russian Nukes at this time was more from the fact that so many of the U.S.S.R. nukes went missing during this period.

Of course, if you noticed a few paragraphs back, I said Intentional Nuclear War, I wasn't kidding. The larger threat is equipment malfunctioning and behaving as if there were inbound targets when there were not. In the moment, these false alarms would have likely triggered an all out Nuclear Exchange if not for some quick thinking. In 1979, NORAD computers experienced an error when they detected a full scale launch from the USSR inbound from the states. Retaliation orders were prepped, but the panic was called off when early warning radar failed to confirm any inbound missiles. As they discovered, the alert was tripped when a training scenario for the system was allowed to play on the live data systems by mistake. Here, disaster was averted because, despite a launch detected, there was nothing inbound.

In another scenario, one man literally saved the world when Lt. Commander Stanislav Yevgrafovich Petrov was on duty and the Soviet Early Alert system reported that five U.S. Minute-Man missiles had been launched and were inbound to the U.S.S.R. Again, his staff had a panic moment, but Lt. Cmd Petrov spotted the problem, namely, that there were only five missiles inbound, and pointed out that any U.S. First Strike would be massive... Five missiles to destroy the whole of the Soviet Union was not how the United States would start a nuclear war. Coupled with the fact that the satellites involved were new and there were possible buggy problems, he declared the incident a false alarm. His hunch was confirmed to be caused by some bizarre atmospheric conditions and sunlight making an illusion that tripped the satellite in orbit.

Both these stories show that a Nuclear Launch and impact has components that an alien ship would not necessarily display on radar and early warning launch detection that would be characteristic. Of course, the sudden destruction of London without any other impacts would not look like a nuclear exchange immediately enough that Moscow would reduced to a greasy black smudge on a map. Even, if some how, the radar and the satellites said it looked like a duck, the fact that London and only London was hit would prompt high tensions, but not an immediate all out war.

In military doctrine, especially related to Nuclear War, there are two types of targets: Counter-Force, and Counter-Value. London would be a Counter-Value target: A military target that, while not valuable to the war effort, is incredibly valuable for other reasons (like being a major world city). Though some of that value could translate to the war fighting effort, the sheer loss of wealth and life is the initial value in softening it for invasion. In Nuclear War, the real good targets are Counter-Force... aka other nuclear sights. This is why the U.S. is frequently seen with ground nukes in the center of the country instead of the coasts... because it's impossible for air plane nukes to get that far inland and it's easier to get them to launch without being destroyed by a first strike. This is also why Russian Nukes launched from ground are mobile... and why Submarines are so much valuable (they are both mobile and stealthy... they're almost always a Second Strike platform, as opposed to air and ground being First Strike exclusive. It's nice to blow up a city of 8-10 million people... but from the perspective of Nuclear War, the victory is blowing up an empty field with a multitude of nuclear silos under the ground.

Finally, the U.S. and U.S.S.R. maintain the "Red Line" which is an emergency communications channel from the Kremlin to the White House for the express purpose of figuring out what the hell without declaring a war. The mysterious explosion of London would prompt the yelling of both sides and insistence that they didn't do anything (it's not a real telephone, mind you... it's more of text base communication with translations so dictating, sending, translating and answering help to slow all of this down further).

With all of these factors, the governments, while confused about the sudden crash and destruction of London, would be hesitant to let the nukes off the chains for the time being... of course, the U.S. and U.S.S.R. would certain suspect the other was up to no good, but neither wants to die in a war for an action they didn't do and would insist on trying to work out the cause that gets them out of WWIII.

One of the best places to look for answers in this is the Vela incident, where one of our satellites detected a nuclear event in the South Atlantic. What's great about that incident is that, because it was never fully confirmed, there's a great deal of information available regarding what sensors did or did not detect.

The key to the incident was the Vela satellite constellation. They were designed to detect the characteristic light signature of a nuclear event. Nuclear events have a curious pattern known as the "double flash" which occurs as the shock front extends past the fissile material. It is extremely difficult to replicate this. One can either replicate the timing with low power devices, or the raw brightness with high power devices, but we do not know of any event which causes both, other than a nuclear explosion. The Vela incident was a case where the satellites detected such an event.

What made the event interesting was the lack of collaborating evidence. There were
acoustic sensors like SOSUS which failed to detect an explosion. There are also seismological sensors that we use, which also came up negative. We detect transient changes in the ionosphere. We also look for the radioactive byproducts of a nuclear event in the atmosphere.

In the case of the Vela incident, these other sources were inconclusive. To this day, it is not fully resolved whether this was a covert nuclear test or if it was a one-time event in space generating a false positive. Regardless, for your purposes, these are some of the sensors we would bring to bear in such an event.

There would also be questions as to the origin of the event. Nations have strategically placed radars to make it exceedingly difficult to launch a nuclear weapon at them without it being detected. If no such radar tracks occurred, that would lead to questioning how the event took place.

There are two possibilites: either they detect the ship before impact, and thus they know it can't be a missile due to size and trajectory, or either they don't detect it before impact and thus they can't guess it's a russian attack. This second possibility is way more likely, since you want this ship to destroy part of London and to do that it must be a really massive spaceship and/or going insanely fast - if the ship was at Newton's mercy, about 11 Km/s. The missile detection systems of the 80's, just like the actual ones, are pointing down to Earth to detect missilies flying up. The ship would be detected by conventional radar, mere seconds before impact.

In any case, while a big impactor can destroy a city releasing as much energy as a nuclear bomb, it has a very different signature. You can blow up things with C4, you can blow things with gunpowder, you can blow things with gasoline or you can blow things with a nuke. With enough material you can destroy as much with any of these methods, and after the fact they are equally destroyed, but it's pretty simple to tell them apart. You don't even need to be an expert. There's no way anybody would mistake a meteorite-like impact from an airburst thermonuclear bomb. To start with, the former will produce a big crater while the latter won't.

If part of London is blew up, the first description of the event by a survivor minutes or seconds after the impact would be enough to rule out a nuclear strike.