Photograph by Mel Evans/AP Photo

When Software Catastrophe Strikes

  1. Wall Street's Knightmare

    Wall Street's Knightmare

    Technology can seem larger than life—as when NASA scientists, say, expertly deposit a car-size, plutonium-powered rover onto the surface of Mars. Yet we are frequently reminded that computer programs are written by people and, therefore, are subject to human error. The Knight Capital Group (KCG) glitch—which cost that company $440 million on Aug. 1 after a new version of its automated trading software went haywire, spewing erratic stock trades—is the latest in a string of costly and destructive coding failures. The damages range from lives lost, to exploded rockets, to homes left in the dark. Here's a list of some of the most significant computer bugs in history.

    Photograph by Mel Evans/AP Photo
  2. Ariane 5 explosion (1996)

    Ariane 5 explosion (1996)

    After a decade of development, the European Space Agency launched the unmanned Ariane 5 rocket on June 4, 1996. Less than 40 seconds after takeoff, the rocket, carrying millions of dollars worth of scientific equipment, exploded over the swamps of French Guiana. The culprit: a coding error. The software was not protected from integer overflow, a computing mishap that occurs when a program attempts to stuff a 64-bit number into a 16-bit space.

    Photographs by ESA/CNES; ESA
  3. Thera-25 overdose (1985-1987)

    Thera-25 overdose (1985-1987)

    The Therac-25 was a radiation-therapy system designed in the mid-1980s as a replacement for its predecessor, the Therac-20. It was meant to deliver two types of therapy: low doses of high-energy electrons over short periods of time and X-rays produced by directing high-energy electrons into a target, which when working correctly would spread the beam over a larger area. But poor programming and development led to a bug, called a “race condition,” that made it possible for the high-powered beam to fire without the target in place, leading to lethal overdoses. From 1985 to 1987, three patients died from radiation poisoning.

    Photograph by Roger Ressmeyer/Corbis
  4. AT&T phone system collapse (1990)

    AT&T phone system collapse (1990)

    On the afternoon of Jan. 15, 1990, a Manhattan phone switchboard crashed. Normally such a malfunction could be easily remedied. But there was a defect in the new software AT&T (T) had installed to control its long-distance service, causing the crash to spread, rolling from one switch system to the next. The chain reaction led to 114 switches crashing, leaving 60,000 people without phone service. During the nine hours it took to reinstall the old software, it's estimated that the company lost more than $60 million in unconnected calls.

    Photograph by Bob Rowan/Progressive Image/Corbis
  5. Lethal cancer treatments (2000)

    Lethal cancer treatments (2000)

    At Panama’s National Institute of Oncology in November 2000, 28 cancer patients were overexposed (PDF) to radiation because of a technical error in the medical equipment. The software, created by a U.S. company, Multidata Systems, was designed for a radiation therapist to draw four “blocks,” which will protect healthy tissue from radiation, on the computer screen. But doctors discovered a way to draw five boxes. They were unaware of a glitch in the system that caused the device to release twice the radiation when the boxes are drawn a specific way. Nine of the patients have since died, with five of the deaths attributed directly to lethal radiation exposure.

    Photograph by Mark Kostich/Getty Images
  6. Mariner 1 misfire (1962)

    Mariner 1 misfire (1962)

    It’s been called the most expensive typo in history. In 1962, NASA launched Mariner 1 to collect scientific data about the planet Venus. A missing hyphen in the programming code, however, forced operators to abort the mission less than five minutes after takeoff, obliterating the rocket over the Atlantic Ocean. An investigation found that a formula had been incorrectly transcribed, causing the missile’s trajectory to be miscalculated.

    Photograph by NASA/KSC
  7. East Coast blackout (2003)

    East Coast blackout (2003)

    For up to four days in the middle of a hot spell, 50 million residents across eight U.S. states as well as Ontario were left without electricity. The largest power outage in North American history began shortly after 4 p.m. on Aug. 14 when a high-voltage power line in Ohio failed. Normally, that would trigger an alarm so operators could distribute the energy between lines. But a software glitch in the management system caused a communication failure, and one by one, energy grids overloaded and shut down. The blackout is estimated to have cost New York City alone $1.1 billion.

    Photograph by Daniel Acker/Bloomberg
  8. Soviet pipeline hack (1982)

    Soviet pipeline hack (1982)

    Not all bugs are the result of error—some are malicious. A former U.S. Air Force secretary, Thomas Reed, alleged in his memoirs that the Central Intelligence Agency embedded a logic bomb—a piece of code intentionally inserted into a software system to wreak havoc when triggered—in a Canadian computer system. The agency had been tipped that the Soviet Union planned to steal the program to control its trans-Siberian gas pipeline. Reed said the sabotage led to a massive pipeline explosion in June 1982. There were no fatalities.

    Photograph by Val Mazzucca/AP Photo
  9. Y2K bug (2000)

    Y2K bug (2000)

    The world braced itself for widespread computer catastrophe ahead of the changeover from 1999 to 2000. Programmers had been using a two-digit system rather than four to represent the year. In theory, that would mean software would not be able to distinguish between 1900 and 2000 and, therefore, shut down. Companies and governments invested billions to upgrade computer systems. When the new millennium arrived without virtual mayhem, many wondered if the problem was overstated to begin with.

    Photograph by Mike Derer/AP Photo
  10. Mars Orbiter disappears (1998)

    Mars Orbiter disappears (1998)

    In December 1998, NASA launched the Mars Climate Orbiter, a 750-pound spacecraft intended to study the planet’s climate. The $193 million device, however, was lost soon after it began orbiting Mars. The root cause: a Lockheed Martin (LMT) engineering team helping to design the probe used English units of measurement in calculating thrust while the agency's software employed the metric system. The discrepancy prevented navigation data from transferring among the Orbiter, engineering crew, and NASA experts. NASA believes the spacecraft was torn apart in the low Martian atmosphere.

    Photograph by NASA