Any space mission is a very expensive project, and if we are talking about sending vehicles to other planets, even more so. At the same time, every attempt to explore space carries great risks, because a lot of things can go wrong: from hardware failures to software glitches (and there are also “external” factors like collisions with space debris or meteorites). Fully aware of this, space agency engineers try to think ahead and be safe, but their efforts are not always crowned with success.
One of the most famous failures of cosmic proportions (in every sense of the word) is associated with the usual hyphen (almost). In this article, we understand how it arose and what conclusions scientists made to get rid of such errors in the future.
The oversight is doubly unfortunate due to the fact that the mission was debut
On July 22, 1962, Mariner 1, the first automatic interplanetary station of the Mariner program, designed to study the planets closest to Earth, was supposed to head to Venus. The spacecraft was created to determine the temperature of Venus, as well as to measure magnetic fields and charged particles near the planet. In fact, this was the end of the Mariner-1 mission.
Nevertheless, the launch of the first apparatus to Venus was important not only for science, but also for political reasons: it was the next stage in the space race between the USA and the USSR. After the exploration of the Moon, it was Venus that became the most attractive target for scientists – at least because it is the closest planet to Earth.
The best time to send missions to our neighbor comes every 19 months, when Earth and Venus are closest to each other. It was at this moment that scientists decided to become attached: in 1957, none of the superpowers had the necessary technologies, and by 1959 the Americans did not have time to create the necessary probes. In 1961, the United States did not launch a single space mission, but the USSR sent “Venera-1” – it became the first spacecraft to fly past this planet.
After that, the Americans had to give their answer, and they became Mariner-1.
💡 Unlike the Pioneers and Voyagers, the stations of the Mariner program were intended for relatively short-term operation in space – from several months to three years.
Fatal hyphen (not quite and not only him)
The mission to launch Mariner 1 went wrong from the very beginning – almost immediately after takeoff, the Atlas Agena launch vehicle began to deviate from the desired trajectory. Scientists sent corrective commands to her, but they led to an even greater deviation, which created a threat to ships in the North Atlantic Ocean and nearby communities. Because of this, the device had to be destroyed – the site security officer sent the rocket a self-destruct command just 293 seconds after launch.
The experts did not have too much time to find out the reasons for what happened because of the limited launch window (the period in which a rocket can be sent into space without the risk of colliding with other vehicles). They put forward several hypotheses, and the official conclusion was made in less than a week. The cause was cited as a combination of factors.
According to official information, during the launch, the launch vehicle lost contact for a short time. At that time, this was no longer uncommon, and the launch vehicle was pre-programmed to move along a given course until communication was resumed. However, by the time the problem was fixed, the software had erroneously detected an unsteady speed fluctuation and attempted to correct it, causing the course to be off course. Sending corrective coordinates made the situation even worse.
The combination of two factors – loss of communication and incorrect operation of the on-board computer – led to the fact that the ship had to be blown up.
Subsequently, analyzing the software, scientists discovered the absence of an underscore in the code:
Without smoothing, which is what the dash above (scientifically called “macron”), the program perceived the standard small changes in speed as extremely serious – as a result, the software made unnecessary corrections that knocked the rocket off course.
The investigation showed that the macron was lost when transferring a handwritten equation into the program. In fact, this happened even before the preparation for the Mariner-1 mission – there was no dash in the meaning in the previous launch of the Atlas-Andrzej launch vehicle, but it was successful, since the antenna did not lose communication with the on-board computer (in the software which there was an error) did not have to take control.
Where did the story about the hyphen come from? From the official comments of NASA employees and others responsible for this project, who had to report to Congress and the general population of the United States. The “missing hyphen error” claim was much simpler and clearer than explaining the role of the macron in that ill-fated formula.
The version about the “hyphen” quickly scattered in the media and not only – the New York Times and writer Arthur Clark called the error “the most expensive hyphen in history”, which probably fueled public interest in this case and made it one of the most famous among all the failures in space exploration.
💡 There is another version of Mariner-1’s failure, according to which in the expression “DO17I = 1, 10″ was given a dot instead of a comma, which is why Fortran interpreted it as assigning the number 1.10 variable DO17I instead of repeating the loop 10 times. However, this hypothesis has not been officially confirmed.
Scientists draw conclusions and rethink preparation for space missions
Even aside from the reputational blow, the loss of Mariner 1 cost NASA $18.5 million (about $185 million in March 2023 exchange rates).
💡 NASA had a copy of Mariner 1 ready in the face of Mariner 2, and since the problem of the debutant was identified, its successor was launched quite quickly – two months later, on August 27, 1962.
The Mariner 1 case once again showed not only the importance of carefully debugging software before launch, but, most importantly, it emphasized the need to design programs in such a way that minor errors in the software could not lead to critical failures. Scientists fully realized this and changed their approach, which turned out to be useful in practice – the programs of some spacecraft of the Apollo project (manned space flights to the Moon) contained errors, but they did not lead to critical consequences, including thanks to the experience with the Mariner- 1″.
In addition, NASA resorted to another strategy – it began launching some spacecraft of the Mariner program in pairs to reduce the risk of failure.