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CHAPTER 2 The Broadside of a Barn

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Dave walked into the office Monday morning and was immediately whisked off to the conference room by Chief Master Sergeant Bowls. There was a commotion for sure. Colonel Haase and Bill Green were in a heated discussion over something. Normally you don’t see a full bird, especially the Wing King, and a GS-14, going toe to toe. But Bill was standing his ground and not backing down. Lieutenant Sheridan started to catch on to the gist of the conversation.

The colonel asked, “Bill, what do you mean when you say that we couldn’t hit the broadside of a barn? Do you mean that all fifty-four birds are pointing in the wrong direction? You’re crazy!”

“No, sir, but it is very simple,” Bill responded coolly. “Every silo that was aligned for targeting, and was calibrated when the standby generator was running, now has a built-in error. It is simple thermodynamics. Let me explain. The exhaust gas from the generators runs directly under the collimator room on level two of the silo. The huge chunk of concrete and steel that the collimator sits on collects the heat from the exhaust. Then all that concrete and steel expands. Even if it is by only a quarter inch or so, this makes for a huge targeting error.”

The colonel’s lip curled up a bit. “Okay, hold it right there. This conversation is over. This conference room is not cleared for discussions this sensitive.”

Haase picked up the phone and punched in the CCC, the Combat Control Center. “I’m bringing my engineering staff over in ten minutes, make the SCIF room available.” This was the Secure Communications & Intelligence Facility.

Haase, Bill, Sheridan, and both Chiefs walked out of the HQ Building and down the road to the CCC. The colonel coded in and signed in the rest under his escort. He pointed to the SCIF room. Everyone crammed themselves in around the conference table and sat down.

“Okay, Bill, how’d you figure this out?” Haase asked. “If you’re right, then thirty percent of our nuclear capability is sitting out there pointing at who knows what!”

Bill stated that he figured it out when they were doing work on a blast valve overhaul project at complex 374-5. The silo exhaust air shaft has a valve that protects it from an outside blast wave. Any explosion topside would simply push the blast valve shut and the overpressure would then be routed through and around the delay piping to dampen the shock. As might be expected, the tolerances on the actuators and seals associated with this critical valve are very tight. When putting things back together after chrome plating the components, nothing seemed to fit. The dimensions were triple checked. However, nothing lined up. It had to be a misalignment of the silo structure itself.

Bill explained that when surveying equipment was brought out to the Site, they needed to establish a baseline or reference to measure the blast valve housing alignment. The steel plate on the collimator shaft was a known benchmark. After all, it was used for targeting the ICBM. Its exact location on Earth was known down to a gnat’s ass.

During the process of using a theodolite to shoot their measurements from the collimator room, the Launch Control Center radioed Bill and notified him that they were about to fire up the standby generator. The generator is run for eight hours a week to ensure its operational capability. The standby generator is a critical piece of launch equipment. Bill acknowledged the transmission from the LCC. The generator kicked on and then the clicking sounds were heard a few minutes later as the motor control center relays and switching gear transferred site power from commercial over to standby.

Bill explained that when he went back to taking his measurements after about three hours it was getting a little warm in the collimator room. This was expected and understood. After all, they were sitting over the exhaust pipe and water jacket of the generator. However, what wasn’t expected was that when he took a theodolite reading from his surveying equipment it completely missed its mark. It was a full half inch off. The implications immediately sunk in. The bench mark was not a fixed stable platform! This could lead to alignment and targeting errors when performing targeting sets!

Haase absorbed all of this. He knew Bill was right. He calmly stated, “All right Bill, you’ve convinced me. Now we are going to punch up SAC HQ and you’re going to explain it all over to the battle staff.”

Haase punched up SAC HQ on the STU-II. The STU-II is a special telephone instrument that can be switched to a secure mode for discussion of classified information. The abbreviation STU-II stands for Secure Telephone Unit-2nd generation.

If a person needs to discuss classified information, you can use the STU-II in non-secure mode to place a call to another party who also has a STU-II. After the connection is made, you ask the party receiving the call to “go secure.” You and the other party then put your crypto-ignition keys (CIKs) into the phone terminal, turn them on and press the SECURE button. It may take about fifteen seconds for the secure connection to be established. He then punched up the speaker phone.

After Bill and Haase explained the situation to the battle staff, both sides of the conversation went quiet for a minute. Haase had to ask if there was anyone on the other end. After a few seconds the word came back.

The topic was closed for discussion and any mention of it would be a breach of national security. Besides, planned upgrades in the guidance package would fix the problem.

Lieutenant Sheridan spent the next couple of years modifying the launch complexes and upgrading the guidance package for the Titan II ICBMs.

As it turned out, one of the best kept secrets of the cold war was that the Russians and the US could not hit the broad side of a barn with their land based ICBMs. Several of the assumptions and constants taken into consideration in the targeting algorithm were in error.

The fact that most of our ICBM force would not have hit the broadside of a barn during the cold war might startle some. However, accuracy is a relevant term when it comes to nukes. When you’re talking about a ten megaton nuclear war head (the largest in the US inventory at the time) being close means taking out an entire city such as Moscow or only half the city.

The ol’ SAC adage of “Nuke them until they glow and then strafe them at night” had some ring of truth to it.

The funny thing about targeting errors is that the same thing happened as artillery became more powerful and ranges increased to over twenty miles. The simplistic parabolic trajectory calculations no longer applied. The projectiles were actually following a suborbital path. This path was elliptical and must take into account the curvature of the Earth.

By World War II, there was a demand for more accurate calculations to improve accuracy. Rooms full of humans were employed in computing artillery trajectories, and the result was unacceptable error. A variety of computing research projects were undertaken at Princeton University, Harvard University, and the University of Pennsylvania. These resulted in room-size computers such as the Mark-I through Mark-IV, and the ENIAC. All of which used vacuum tubes. The vacuum tube machines were erroneous. Tubes were always burning out or their response drifted frequently. This consumed a huge amount of power and generated a large amount of heat. And, they were slow. Less than 10,000 integer multiplications per second compared with the gigahertz or billions per second common today. They were also difficult to program, but provided a useful test bed for basic computer concepts.

It seemed that we have now come full circle. ICBM targeting could also no longer be counted on to depend on the simplistic targeting algorithm of the day. The Titan II missile system was designed to destroy enemy strategic targets in a minimum amount of time. To do so, the warhead must be placed on a target with a high degree of accuracy and from a distance of over 5,500 miles. This degree of accuracy is comparable to hitting a golf ball into the cup 150 yards away or making a hole in one from a par three. It is obvious that many variables must be considered in attaining this degree of accuracy. The powered portion of flight lasts less than one sixth of the total flight time or about five minutes. Control of the flight path was not possible after powered flight ends. The missile goes into a ballistic free fall for the remainder of the flight.

Several parameters must be met before the end of powered flight to permit the warhead to arm itself and free-fall to the target. All missile systems exist solely for this purpose. The targeting of a Titan II ICBM involved an algorithm containing only 13 parameters. These include obvious variables such as launch site and target coordinates, velocity, altitude, and even barometric pressure. However, there are other not so apparent variables that enter the equation.

Polar motion produces variations in several parameters employed in targeting computations which are traditionally treated as constants. These include the Earth’s angular velocity vector, launch site gravity magnitude and astronomic coordinates, and target and launch site inertial velocities. The resulting targeting error is assessed for each of these quantities. The dominant error is shown to be the Inertial Measurement Unit (IMU) azimuth alignment error. This results in a large cross-range error caused by a shift in the Earth’s poles.

Why is this important? Because all of the test launches of our ICBM fleet were launched from Vandenberg AFB on the California coast and launched westward towards the Johnson Island Atoll or Kwajaline Atoll about 5,550 miles out into the Pacific Ocean. This westward launch did not adequately simulate an actual launch over the pole to the north. Going over the pole represented a whole slew of challenges and problems not fully understood or anticipated.

The IMU azimuth alignment relied upon celestial navigation. The azimuth was determined using an optical collimator that consisted of basically a periscope using a mirror and prism system that was piped down through the silo and into the reentry vehicle (RV), the polite and politically correct term for nuclear warhead. This optical system established the missiles exact coordinates on Earth in reference to the pole using the North Star as a bench mark. This was done based upon the position of the North Star timed with the aid of an atomic clock. A small measurement error on the launch end represented a huge error on the target end of the trajectory. Gravitational “anomalies” were also encountered when flying over the poles as was experienced with spacecraft placed in polar orbits.

Every object in the universe attracts every other object in the universe with a force (F) directed along the centers of the two objects proportional to the product of their masses (M1 and M2) and inversely proportional to the square of the distance between the two objects (R). This is the basis of the famous Newtonian formula below:

F = G (M1 × M2)/R2

where G (Gravitational constant) = 6.67300 × 10-11 m3 kg-1 s-2

Don’t confuse this “big G” with “little g”. Big G is considered a universal constant or the same number throughout the known universe. Little g is the known as the acceleration due to gravity. On Earth, it is normally about 9.82 meters per second squared. That means that when an object is dropped it falls at a rate of 9.82 meters per second for the first second. After the next second it falls at 17.64 meters per second. After the third second it is falling at 26.44 meters per second and so on and on as it picks up speed. It is also conceded that little g is not a true constant but varies from the pole to the equator and due to the pear shape of the Earth. It can also be affected by the relative mass and density of materials such as mineral deposits, mountain ranges, ice packs, and ocean depths. It has to do with the amount of mass beneath your feet.

These deviations in little g have been fairly well understood and even mapped by geologists, oil companies, and the Colorado School of Mines. Even with all the targeting deviations, precessions and errors known, it was nearly impossible to validate that the algorithm was correct when you had to launch a missile toward the North Pole to prove it. The Russians and Chinese would take a dim view of this. Anything remotely approaching the pole would be considered a threat.

Thus, the only other alternative was to map out the gravitational anomalies and account for them in the targeting algorithm. This gave birth to a multibillion dollar black program called Delta G in deference to the changing gravitational constant.

Newly promoted First Lieutenant Sheridan was now about to embark on another career broadening experience. He was summoned to Headquarters at North American Aerospace Defense Command (HQ NORAD) at Cheyenne Mountain near Colorado Springs. One of NORAD’s primary functions was to track space-borne objects in orbit around the Earth. This included all satellites, and space junk down to the size of a tennis ball. As a matter of fact, one of their smallest objects tracked was a glove that floated loose from a spacewalk operation out of a Gemini capsule. NORAD uses a combination of radar and optical sensors to track and catalog over 9,000 space objects.

Another mission includes a Laser Clearinghouse (LCH) for laser operations and Collision Avoidance (COLA) for NASA; both functions are intended to protect on-orbit assets. COLA and LCH use the computer projections to propagate objects over the laser emitter or launch site to determine if there is a possibility of collision.

Sheridan was escorted into Cheyenne Mountain by Captain Dennis Murphy. The entry procedures were similar to those for the Titan sites. Once inside the giant drive-thru blast doors, they hopped into an electric golf cart that whisked them the 300 yards into the cavernous operational control center. This place looked like a launch control center on steroids. Again, everything was shock mounted and situated on huge isolation platforms. Murphy led Sheridan into one of the modules and then down a hallway into a conference room. Sheridan had to smile at the cherry wood paneling, table, and furniture. For a place built to last beyond doomsday, no expense was spared on the details and little things in life.

General Ron Giffen entered the room along with a staff of a half dozen technicians and asked, “Sheridan, do you really know why you are here?” The question took him back a little. He responded sharply, “Sir, I was told to attend a briefing on orbital tracking, space operations, and targeting algorithms.”

Giffen replied coldly, “Sheridan, this operation is classified TS and just to be clear that you know the ramifications, I’m sending you to the North Pole afterwards to implement the operational plan,” added the General. Dave didn’t see that one coming as his jaw dropped.


Giffen continued, “You’re now a world class subject matter expert on ICBM targeting and are intimately aware of the fact that launching an ICBM over the pole makes it about as accurate as my tax return. The only saving grace with the Titan is that it carries one hell of a punch. That ten megaton warhead means you only have to be close. However, we have other problems.”

The General paused for a moment for dramatic effect, “ICBMs aren’t the only thing we launch over the poles. The Space Shuttle is due to be launched out of Vandenberg from SLC-6 in a year or so. We’re going to put it in a polar orbit to augment our reconnaissance satellites that are currently in a polar orbit.”

General Giffen stood up and walked over to the wall display, “Now with that said, I want to show you something very interesting.” He had one of the technicians call up a program showing a graphical representation of the Earth and several thousand objects apparently in orbit. “Sergeant, delete all objects not in polar orbit at or below eighty degrees north latitude.” The screen now showed only a few dozen objects.

“Lieutenant, these objects represent the satellites that we and the Russians have in polar orbit. Sergeant Keen, filter out the space junk now.” Only a handful of satellites were visible on the display. “Lieutenant, there is nothing particularly fascinating about this plot. However, if you plot the orbit by looking down directly over the pole you will notice some interesting dynamics taking place. These satellites were designed to stay in orbit for seven years. There is enough maneuvering fuel on board to reposition and provide for station keeping. Now, Sergeant, show a plot of the orbits for the next five years filtering out known deviations, perturbations, precession and known errors without station keeping.”

Lieutenant Sheridan couldn’t believe his eyes. The plot looked like a kid’s Spirograph with lines spiraling off in every direction. “Okay, Sheridan, you’ve seen it. There is not enough steering fuel on board to keep these birds in a polar orbit for four years let alone seven. Clearly there are some forces acting on these satellites that are unseen and unaccounted for in our orbital calculations. They are not random errors. A statistical analysis proves there is a very perceptible left hand twist to these polar orbits. Depending upon altitude, each one of these satellites takes up to a one second degree of left hook on each orbit. At ninety minutes per orbit, this adds up to quite a deviation over a month or two. We can’t afford to keep sending up more hundred million dollar satellites every few years. Thank God, the Russians are even worse off than us.”

“Your job is going to be to figure out what the hell is going on. We’re sending you to the Greenland icecap to find out. Congratulations, Captain Sheridan,” as General Giffen handed Dave his new silver bars.

Delta G

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