On September 23, 1999, after nearly ten months of an arduous journey to Mars, NASA engineers were preparing to place the Mars Climate Orbiter into orbit around Mars. With everything ready to celebrate the success of the mission, the probe hid behind the planet and never came out again, they lost control of the device and it ended up crashing on Mars. Someone forgot to convert from imperial to metrican oblivion of 125 million dollars.
Over the years it has become one of NASA’s biggest failures and also a valuable lesson to be learned. Mars Climate Orbiter has gone down in history not for reaching Mars, but for showing us that using a measurement standard is essential. Also how important it is to get things right, especially if you’re taking a tens of millions of dollar project to Mars.
My software in SI, your pieces in imperial units
Now, how could a group of engineers like those at NASA get it wrong by converting between different units? They actually did not make the conversion calculation wrong, as this story is often told. The problem is that part of the project was designed using the Imperial System and part using the International System.
At that time, NASA had already started to use the International System, which is used by the scientific community throughout the world. However, the United States continues to use the Imperial System and therefore many NASA vendors also used this system when manufacturing its parts, components and other products for NASA. Although NASA required the component data to be converted, vendor Lockheed Martin did not. And what happened happened.
Engineers assembling the Mars Climate Orbiter, that is, mixing components with Imperial System and International System.
One of the pieces of software that Lockheed Martin supplied operated and sent its results in pounds as a unit of force. The NASA system that collected these data, however, was designed using the International System with Newton as the unit of force. A communication error between different parts of the operating system.
The catastrophe built up bit by bit over the months of the Mars Climate Orbiter voyage. The system calculated the impulse that the probe had to take each time the engines were turned on and from the NASA control center this impulse was being sent in such a way that the probe would remain in a specific position to enter orbit properly. But of course, since the data is incorrect every time the engines were started the probe kept drifting of your expected journey.
Finally, when it approached Mars, the probe was on a trajectory that would place it at an altitude of between 150 km and 170 km (relative to Mars). It was scheduled to orbit at an altitude of 226 kilometers, but since the minimum at which it was safe to place the probe was between 110 km and 80 km, they decided to go ahead. The reality was worse, the probe did not reach Mars at a height between 150 km and 170 km, but entered orbit at a measly 57 km from Mars.
We do not know exactly what happened because the connection with the probe was lost when it was circling the red planet, but it is assumed that it entered the upper atmosphere, thus causing its fall on and subsequent destruction. It is also possible that it deviated from orbit and continued its journey through the Solar System. What is clear is that Nothing more has been heard of her for two decades..
The Mars Climate Orbiter probe before being sent to Mars.
How did no one notice before? Well actually yes. During their journey from Earth to Mars, some engineers realized that the desired trajectory was not matching the data they were receiving from the probe. Normally these errors are solved by making a correction on the trajectory, but this time it was necessary to make more corrections than usual. Apparently they tried to open an investigation in this regard, although nothing was finally achieved.
Is Lockheed Martin the company responsible for the failure of the mission? For NASA, which subsequently opened an in-depth investigation to understand the cause of the failure, no. The organization assumes the failure of the mission as its own due to poor project security management. By not carrying out the appropriate checks and controls that would have made it possible to detect the discrepancy in the data due to the different unitary systems that were used.
Years later it seems that we have learned our lesson. Many other probes have been launched into space and several of them with the goal of reaching Mars. In recent years we have not only seen US missions like Perseverance, but also the arrival of other countries like China and the United Arab Emirates.
Among the next missions to reach the red planet could be Indian Mangalyaan-2, in addition to the joint ESA-NASA Mars Sample Return mission. ESA’s other long-awaited mission to Mars, ExoMars, was put on hold last year as it depended on collaboration with the Russian space agency Roscosmos.
United States vs. the world
That as humans we have explored Mars and we still have errors for using different measurements is at least inexplicable, but more inexplicable is that in the middle of 2020 and in a more global world that will never continue to exist different unitary systems. Today only four countries (actually three because in the UK it is mixed) use the imperial system still. Two of them are (in context) insignificant globally: Liberia and Myanmar. The problem is that one of the main world powers, the United States, maintains the system. And there are those who defend that it is better.
Regardless of all the advantages that the metric system has been shown to have, it is not that easy to change usage in an entire country. It is not that they have not tried, in fact the United States Congress approved in 1975 through the ‘Metric Conversion Act’ the SI as the preferred unitary system. This law did not prohibit the Imperial System, so it continued to be present and companies continued to bet on this system in their consumer products.
Graph that shows the inconsistencies of the Imperial System against the International System.
Why didn’t you adapt? Because learning a new system is complicated, it frustrates people, and companies don’t want customers who are frustrated with their products. Just as we (those who use the SI) find the Imperial System incomprehensibly complicated, they find the International System confusing with respect to the Imperial System.
But change is possible, some countries currently have a mixed system that is increasingly towards the SI. Others, such as Canada, for example, made the transition in 1970, although it took more than fifteen years. Whatever the Americans wish to use, the scientific community and the main organizations have adapted the International System By consensus, a repeat of the Mars Climate Orbiter case is less and less of a threat.
Via | 99% Invisible
More information | NASA and Wikipedia
Images | POT
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