The False Alarm That Nearly Sparked Nuclear War

April 16, 2021 by Lewin Day 54 Comments

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

March 25, 2020 by Mike Szczys 13 Comments

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

July 2, 2019 by Kristina Panos 52 Comments

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

April 9, 2019 by Tom Nardi 75 Comments

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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The Age Of Hypersonic Weapons Has Begun

January 7, 2019 by Tom Nardi 188 Comments

With a highly publicized test firing and pledge by President Vladimir Putin that it will soon be deployed to frontline units, Russia’s Avangard hypersonic weapon has officially gone from a secretive development program to an inevitability. The first weapon of its type to enter into active service, it’s capable of delivering a payload to any spot on the planet at speeds up to Mach 27 while remaining effectively unstoppable by conventional missile defense systems because of its incredible speed and enhanced maneuverability compared to traditional intercontinental ballistic missiles (ICBMs).

Rendering of Avangard reentering Earth’s atmosphere

In a statement made after the successful test of Avangard, which saw it hit a target approximately 6,000 kilometers (3,700 miles) from the launch site, President Putin made it clear that the evasive nature of the weapon was not to be underestimated: “The Avangard is invulnerable to intercept by any existing and prospective missile defense means of the potential adversary.” The former Soviet KGB agent turned head of state has never been one to shy away from boastful claims, but in this case it’s not just an exaggeration. While the United States and China have been working on their own hypersonic weapons which should be able to meet the capabilities of Avangard when they eventually come online, there’s still no clear deterrent for this type of weapon.

Earlier in the year, commander of U.S. Strategic Command General John Hyten testified to the Senate Armed Services Committee that the threat of retaliation was the best and perhaps only method of keeping the risk of hypersonic weapons in check: “We don’t have any defense that could deny the employment of such a weapon against us, so our response would be our deterrent force.” Essentially, the threat of hypersonic weapons may usher in a new era of “mutually assured destruction” (MAD), the Cold War era doctrine that kept either side from firing the first shot knowing they would sustain the same or greater damage from their adversary.

With President Putin claiming Avangard has already entered into serial production and will be deployed as soon as early 2019, the race is on for the United States and China to close the hypersonic gap. But exactly how far away is the rest of the world from developing an operational hypersonic weapon? Perhaps more to the point, what does “hypersonic weapon” really mean?

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Retrotechtacular: The First Atlas Launch

September 30, 2014 by Kristina Panos 31 Comments

As the Cold War conflict expanded in the 1950s, the Soviet Union dry-tested a hydrogen bomb and defense tactics became a top priority for the United States. Seeking to create a long-range nuclear missile option, the Air Force contracted Convair Astronautics to deliver SM-65 Atlas, the first in series of ICBMs. In the spotlight this week is a sort of video progress report which shows the first launch from Cape Canaveral’s LC-14 on June 11, 1957.

After the angle of attack probe is unsheathed, everyone moves out of the way. The launch is being monitored by base central control, but the swingin’ spot to spectate is the blockhouse. They have a periscope and everything. As the countdown continues, liquid oxygen pipelines whistle and wail into the idyllic Florida afternoon with the urgency of a thousand teakettles. Cameras and tracking equipment are readied, and the blockhouse’s blast door is sealed up tight.

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