On 11 December 1998, the Mars Climate Orbiter was launched.
It had a nine-month journey to Mars.
It was to send back information on the atmosphere, the climate, and the surface of the planet.
All crucial information for subsequent flights.
During the voyage, pressure from the sun caused the spacecraft to twist or roll.
So at least a dozen times a day, little jets had to be fired to correct for that.
The Orbiter was, as the name implies, supposed to orbit Mars.
But when it came close to executing its orbit, they noticed something was wrong.
The orbit was supposed to be 226 km above the surface.
But the prediction showed it would only be 170 km.
They fired the jets to correct.
Hang on, now it was predicting just 150 km.
They fired the jets to correct again,
Huh? Now the predicted orbit was only 110km above the surface.
In a panic they fired the jets and corrected again.
The spacecraft disappeared behind Mars, but now with a predicted orbit of just 60km above the surface.
Mars Climate Orbiter was never heard from again.
It either burned up in the atmosphere or flew off into space.
No one knows.
This meant the loss of $655 million of spacecraft.
When that happens there’s an investigation.
What they found out was the most interesting part of the story.
The engineers at NASA were issuing commands to the spacecraft in feet-per-second.
The computer on the spacecraft was receiving information in Newtons-per-second.
Which is metric.
So they’re talking in inches and being heard in centimetres.
Every time the engineers used the onboard jets for correction they were out by 4.4 feet-per-second.
And they did this at least a dozen times a day, for nine months.
And every time they did it they made it worse.
They didn’t even notice it because they had computers.
And computers are infallible.
So no one noticed anything, until half a billion dollars very publicly went down the toilet.
See, computers can only process the information that’s fed into them.
And that was the problem.
It wasn’t the computer’s fault, it was the engineers’ fault.
The Trajectory Software Engineers, the Propulsion Engineers, the Trajectory Software Operators, the Propulsion Managers.
All these very intelligent people stopped thinking.
No one even considered the basics.
No one even considered there might be something that a human could spot but technology couldn’t.
And every mistake compounded every other mistake.
And after nine months of travelling and millions and millions of dollars it was all for nothing.
Because they expected the technology to do all the thinking for them.
Art Stephenson, the Director of the Marshall Spaceflight Centre, said “Sometimes little things can really make a big difference”.
No shit, Sherlock.