@TodayInTechHist

Daily threads of significant technological events that happened on this day. “Study the past if you would define the future.” -Confucius

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On this day in 1984, Space Shuttle Discovery's engines ignited, then shut down 4 seconds before liftoff. Then a fire broke out on the pad. The fire was invisible. It was the first on-the-pad abort of the shuttle program that would lead to changes in safety procedures A thread 🧵
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On this day in 1993, NASA lost an $813 million spacecraft three days before it was supposed to reach Mars. The worst part was they had no idea what happened. The transmitter was off when things went wrong. A thread 🧵
Mars Observer in Mars Orbit with sun in background. | Image Credit: NASA/JPL, Public domain

ALT Mars Observer in Mars Orbit with sun in background. | Image Credit: NASA/JPL, Public domain

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They never confirmed it. No telemetry, no final signal, no definitive answer. $813 million, 330 days of flight, and the cause of failure is still officially listed as probable. NASA never heard from Mars Observer again.
Mars Observer in Mars Orbit showing the solar pannel. | Image Credit: NASA/JPL, Public domain

ALT Mars Observer in Mars Orbit showing the solar pannel. | Image Credit: NASA/JPL, Public domain

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The camera onboard, the Mars Orbiter Camera, was rebuilt and flew on Mars Global Surveyor in 1996. It took hundreds of thousands of images and became one of the best science instruments ever sent to Mars.
Blueish-white water ice clouds hang above the volcanoes of Tharsis, on Mars. Some of the features in this image have been annotated in Wikimedia Commons. | NASA/JPL/MSSS, Public domain

ALT Blueish-white water ice clouds hang above the volcanoes of Tharsis, on Mars. Some of the features in this image have been annotated in Wikimedia Commons. | NASA/JPL/MSSS, Public domain

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On this day in 1998, Apple put a translucent blue teardrop on a store shelf and dared you to call it a computer. A thread 🧵
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On this day in 1981, IBM unveiled its first mass-market personal computer and accidentally handed the entire industry to its competitors. A thread 🧵
IBM PC XT with green monochrome phosphor screen and 10MB full height 5,25" hard disk drive | Ruben de Rijcke - http://dendmedia.com/vintage/, CC BY 3.0

ALT IBM PC XT with green monochrome phosphor screen and 10MB full height 5,25" hard disk drive | Ruben de Rijcke - http://dendmedia.com/vintage/, CC BY 3.0

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The IBM PC launched at $1,565, about $5,500 today. IBM's previous personal computer, the 5100, had cost up to $20,000. Businesses that had dismissed PCs as toys suddenly took them seriously because IBM's name was on the box.
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IBM sold its entire PC division to Lenovo in 2005. The company that defined the PC standard got squeezed out of the market it created. The Wintel architecture it accidentally standardized still runs most of the world's desktop computers 45 years later.
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On this day in 1950, Steve Wozniak was born in San Jose, CA. He designed the Apple I and Apple II. He raised $1,300 by selling a calculator and a VW bus, and priced the Apple I at $666.66 because he liked repeating digits.
Steve Wozniak speaking at an event in Paradise Valley, Arizona. | Gage Skidmore, CC BY-SA 3.0

ALT Steve Wozniak speaking at an event in Paradise Valley, Arizona. | Gage Skidmore, CC BY-SA 3.0

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On this day in 1945, a B-29 named Enola Gay dropped a single bomb over Hiroshima and killed up to 166,000 people by year's end. It was the first nuclear weapon ever used in war. A thread 🧵
Enola Gay B-29 Tinian 1945 | Modified from: Unknown, Public domain

ALT Enola Gay B-29 Tinian 1945 | Modified from: Unknown, Public domain

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Co-pilot Robert Lewis watched the cloud rise over Hiroshima and wrote five words in his flight log: "My God, what have we done?" Tibbets never expressed regret. He said for the rest of his life that he'd do it again.
At the time this photo was made, smoke billowed 20,000 feet above Hiroshima while smoke from the burst of the first atomic bomb had spread over 10,000 feet on the target at the base of the rising colu | George R. Caron, Public domain

ALT At the time this photo was made, smoke billowed 20,000 feet above Hiroshima while smoke from the burst of the first atomic bomb had spread over 10,000 feet on the target at the base of the rising colu | George R. Caron, Public domain

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Japan surrendered nine days later. It was the only time nuclear weapons have been used in war. The Enola Gay now sits fully restored at the Smithsonian's Udvar-Hazy Center in Virginia, 81 years after that flight.
Panoramic photo of the Enola Gay , the Boeing B-29 Superfortress bomber used to drop an atomic bomb on the Japanese city of Hiroshima in 1945. The aircraft is in the Smithsonian Air and Space Musuem' | Ruhrfisch ( talk ), CC BY-SA 4.0

ALT Panoramic photo of the Enola Gay , the Boeing B-29 Superfortress bomber used to drop an atomic bomb on the Japanese city of Hiroshima in 1945. The aircraft is in the Smithsonian Air and Space Musuem' | Ruhrfisch ( talk ), CC BY-SA 4.0

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