The weakest link in the system is man. Here are the greatest programming disasters in history [TOPtech]

Unfortunately, it also happens that hardware or software failures lead to real disasters. Here are four programming errors that ended in disaster.

Mariner 1 and the most expensive division in history

On July 22, 1962, a rocket was launched from Cape Canaveral, Florida, to launch the Mariner 1 space probe into Venus’ orbit. The purpose of this mission was to provide new information about the hottest planet in the solar system. Unfortunately, the sailor’s flight lasted only 294 seconds. After this time, NASA engineers sent a command to the Atlas Agena B rocket’s onboard system to self-destruct.

The subsequent investigation showed that not one but two failures were responsible for the Mariner 1 disaster. First, the antenna that was supposed to receive commands from the ground control team failed. The designers of the rocket, however, were prepared for this scenario. In the event of an antenna failure, the on-board computer was to execute the flight program according to the commands stored in memory. And here another problem arose. As a result of a human error, one character was missing in the software code, namely the hyphen. This typo meant that even the smallest change in the speed value was treated by the system as a priority.

As a result, the rocket made a series of violent maneuvers and then deviated from its intended course. This in turn forced NASA to destroy it. The famous writer Arthur C. Clarke called this unfortunate typo “the most expensive hyphen in history.”

Therac-25 and deadly radiation

Between 1985 and 1987, there were serious incidents involving the Therac-25 cancer radiotherapy machine. As a result of the failures, which were initially ignored by the manufacturer, some patients received very high doses of radiation, resulting in the death of at least five people.

It turned out that the cause of these tragedies was a specific software error and… savings. Under certain conditions, when the machine operator was operating it quickly, the system allowed multiple operations to be performed simultaneously, which led to incorrect initialization of treatment parameters. A subsequent investigation showed that the manufacturer of Therac-25 copied the software from older models of the device, and at the same time – as part of cost-cutting – removed the mechanical protections used in them. This decision cost at least a few human lives.

Mars Climate Orbiter – pounds or newtons?

The purpose of the Mars Climate Orbiter mission was to study the weather and climate on the Red Planet. On September 23, 1999, the spacecraft began a mission-critical maneuver to put it into orbit around Mars. Radio contact was then lost and never regained. Instead of being at the planned altitude of about 140-150 km above the surface of Mars, the orbiter went to an altitude of only 57 km, which led to its destruction in the planet’s atmosphere.

NASA’s investigation has shown that the cause of the Mars probe’s disaster was human error, or rather a communication error between the two teams responsible for the mission worth hundreds of millions of dollars. It turned out that the ground control team used imperial pounds as a unit of force, while the probe software developed by another team operated in metric newtons. So the spacecraft received instructions in pounds and interpreted them in newtons. As a result, after more than nine months of space wandering, the trajectory of the flight was lower than planned.

Ariane-5 and the laziness of programmers

Designed, among others by the European Space Agency, the Ariane-5 rocket was to be the pride of European astronautics. Suffice it to say that the work on it lasted a decade, and the project budget reached seven billion dollars.

Unfortunately, the maiden flight of Ariane-5, which took place on June 4, 1996, ended in a total flop. The rocket self-destructed just a few seconds after launch. In the course of the subsequent investigation, it turned out that the rocket’s software was largely copied from its predecessor – Ariane-4. One of the functions that was completely unnecessary in the new racket was also copied. The problem is that it was the failure of this function during Ariane-5’s launch that started the chain reaction that led to the rocket’s rapid departure from its intended trajectory.