Radio Apocalypse: America’s Doomsday Rocket Radios

Even in the early days of the Cold War, it quickly became apparent that simply having hundreds or even thousands of nuclear weapons would never be a sufficient deterrent to atomic attack. For nuclear weapons to be anything other than expensive ornaments, they have to be part of an engineered system that guarantees that they’ll work when they’re called upon to do so, and only then. And more importantly, your adversaries need to know that you’ve made every effort to make sure they go boom, and that they can’t interfere with that process.

In practical terms, nuclear deterrence is all about redundancy. There can be no single point of failure anywhere along the nuclear chain of command, and every system has to have a backup with multiple backups. That’s true inside every component of the system, from the warheads that form the sharp point of the spear to the systems that control and command those weapons, and especially in the systems that relay the orders that will send the missiles and bombers on their way.

When the fateful decision to push the button is made, Cold War planners had to ensure that the message got through. Even though they had a continent-wide system of radios and telephone lines that stitched together every missile launch facility and bomber base at their disposal, planners knew how fragile all that infrastructure could be, especially during a nuclear exchange. When the message absolutely, positively has to get through, you need a way to get above all that destruction, and so they came up with the Emergency Rocket Communication System, or ERCS.

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Minuteman ICBM Launch Tests Triple Warheads

On November 5th, the United States launched an LGM-30G Minuteman III ICBM from Vandenberg Space Force Base in California. Roughly 30 minutes later the three warheads onboard struck their targets 4,200 miles (6,759 km) away at the Reagan Test Site in the Marshall Islands. What is remarkable about this test is not that one of these ICBMs was fired — as this is regularly done to test the readiness of the US’ ICBMs — but rather that it carried three warheads instead of a single one.

Originally the Minuteman III ICBMs were equipped with three warheads, but in 2014 this was reduced to just one as a result of arms control limits agreed upon with Russia. This New Start Treaty expires in 2026 and the plan is to put three warheads back in the 400 operational Minuteman III ICBMs in the US’ arsenal. To this end a validation test had to be performed, yet a 2023 launch failed. So far it appears that this new launch has succeeded.

Although the three warheads in this November 5 launch were not nuclear warheads but rather Joint Test Assemblies, one of them contained more than just instrumentation to provide flight telemetry. In order to test the delivery vehicle more fully a so-called ‘high-fidelity’ JTA was also used which is assembled much like a real warhead, including explosives. The only difference being that no nuclear material is present, just surrogate materials to create a similar balance as the full warhead.

Assuming the many gigabytes of test data checks out these Minuteman III ICBMs should be ready to serve well into the 2030s at which point the much-delayed LGM-35 Sentinel should take over.

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Hackaday Links: May 12, 2024

Don’t pack your bags for the trip to exoplanet K2-18b quite yet — it turns out that the James Webb Space Telescope may not have detected signs of life there after all. Last year, astronomers reported the possible presence of dimethyl sulfide there, a gas that (at least on Earth) is generally associated with phytoplankton in the ocean. Webb used its infrared spectrometer instruments to look at the light from the planet’s star, a red dwarf about 111 light-years away, as it passed through the hydrogen-rich atmosphere. The finding was sort of incidental to the discovery of much stronger signals for methane and carbon dioxide, but it turns out that the DMS signal might have just been overlap from the methane signal. It’s too bad, because K2-18b seems to be somewhat Earth-like, if you can get over the lack of oxygen and the average temperature just below freezing. So, maybe not a great place to visit, but it would be nice to see if life, uh, found a way anywhere else in the universe.

Attention Fortran fans: your favorite language isn’t quite dead yet. In fact, it cracked the top ten on one recent survey, perhaps on the strength of its numerical and scientific applications. The “Programming Community Index” is perhaps a bit subjective, since it’s based on things like Google searches for references to particular languages. It’s no surprise then that Python tops such a list, but it’s still interesting that there’s enough interest in a 67-year-old programming language to make it onto the list. We’d probably not advise building a career around Fortran, but you never know.

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The False Alarm That Nearly Sparked Nuclear War

The date was September 26, 1983. A lieutenant colonel in the Soviet Air Defence Forces sat at his command station in Serpukhov-15 as sirens blared, indicating nuclear missiles had been launched from the United States. As you may have surmised by the fact you’re reading this in 2021, no missiles were fired by either side in the Cold War that day. Credit for this goes to Stanislav Petrov, who made the judgement call that the reports were a false alarm, preventing an all-out nuclear war between the two world powers. Today, we’ll look at what caused the false alarm, and why Petrov was able to correctly surmise that what he was seeing was an illusion.

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Ken Shirriff Unfolds A Nuclear Missile Guidance Computer With Impressive Memory

Longtime followers of [Ken Shirriff’s] work are accustomed to say asking “Where does he get such wonderful toys?”. This time around he’s laid bare the guidance computer from a Titan missile. To be specific, this is the computer that would have been found in the Titan II, an intercontinental ballistic missile that you may remember as a key part of the plot of the classic film WarGames. Yeah, those siloed nukes.

Amazingly these computers were composed of all digital logic, no centralized controller chip in this baby. That explains the need for the seven circuit boards which host a legion of logic chips, all slotting into a backplane.

But it’s not the logic that’s mind-blowing, it’s the memory. Those dark rectangles on almost every board in the image at the top of the article are impressively-dense patches of magnetic core memory. That fanout is one of two core memory modules that are found in this computer. With twelve plates per module (each hosting two bits) plus a parity bit on an additional plate, words were composed of 25-bits and the computer’s two memory modules could store a total of 16k words.

This is 1970’s tech and it’s incredible to think that when connected to the accelerometers and gyros that made up the IMU this could use dead reckoning to travel to the other side of the globe. As always, [Ken] has done an incredible job of walking through all parts of the hardware during his teardown. He even includes the contextual elements of his analysis by sharing details of this moment in history near the end of his article.

If you want to geek out a little bit more about memory storage of yore, you can get a handle on core, drum, delay lines, and more in Al Williams’ primer.

Mary Sherman Morgan, Rocket Fuel Mixologist

In the fall of 1957, it seemed as though the United States’ space program would never get off the ground. The USSR had launched Sputnik in October, and this cemented their place in history as the first nation in space. If that weren’t bad enough, they put Sputnik 2 into orbit a month later.

By Christmas, things looked even worse. The US had twice tried to launch Navy-designed Vanguard rockets, and both were spectacular failures. It was time to use their ace in the hole: the Redstone rocket, a direct descendant of the V-2s designed during WWII. The only problem was the propellant. It would never get the payload into orbit as-is.

The US Army awarded a contract to North American Aviation (NAA) to find a propellant that would do the job. But there was a catch: it was too late to make any changes to the engine’s design, so they had to work with big limitations. Oh, and the Army needed it two days before yesterday.

The Army sent a Colonel to NAA to deliver the contract, and to personally insist that they put their very best man on the job. And they did. What the Army didn’t count on was that NAA’s best man was actually a woman with no college degree.

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Humanity Creates A Cloud Of Space Garbage, Again

With the destruction of the Microsat-R reconnaissance satellite on March 27th, India became the fourth country in history to successfully hit an orbiting satellite with a surface-launched weapon. While Microsat-R was indeed a military satellite, there was no hostile intent; the spacecraft was one of India’s own, launched earlier in the year. This follows the examples of previous anti-satellite (ASAT) weapons tests performed by the United States, Russia, and China, all of which targeted domestic spacecraft.

Yet despite the long history of ASAT weapon development among space-fairing nations, India’s recent test has come under considerable scrutiny. Historically, the peak of such testing was during the 1970’s as part of the Cold War rivalry between the United States and then Soviet Union. Humanity’s utilization of space in that era was limited, and the clouds of debris created by the destruction of the target spacecraft were of limited consequence. But today, with a permanently manned outpost in low Earth orbit and rapid commercial launches, space is simply too congested to risk similar experiments. The international community has strongly condemned the recent test as irresponsible.

For their part, India believes they have the right to develop their own defensive capabilities as other nations have before them, especially in light of their increasingly active space program. Prime Minister Narendra Modi released a statement reiterating that the test was not meant to be a provocative act:

Today’s anti-satellite missile will give a new strength to the country in terms of India’s security and a vision of developed journey. I want to assure the world today that it was not directed against anybody.

India has always been against arms race in space and there has been no change in this policy. This test of today does not violate any kind of international law or treaty agreements. We want to use modern technology for the protection and welfare of 130 million [1.3 Billion] citizens of the country.

Further, the Indian Space Research Organisation (ISRO) rejects claims that the test caused any serious danger to other spacecraft. They maintain that the test was carefully orchestrated so that any debris created would renter the Earth’s atmosphere within a matter of months; an assertion that’s been met with criticism by NASA.

So was the Indian ASAT test, known as Mission Shakti, really a danger to international space interests? How does it differ from the earlier tests carried out by other countries? Perhaps most importantly, why do we seem so fascinated with blowing stuff up in space?

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