Brandt's Tumbling Log

If the rocket scientists can't switch to the metric system, what hope is there for the rest of us?

From NASA criticised for sticking to imperial units:

“Given these budget constraints and the need for consistent units throughout the Constellation Program lifecycle to minimise risks, and to contribute to mission success, we’re revising the previous management directive to a primarily English-units-based program,” he says.

That previous directive stems from 2004 when, under continuing pressure from its independent inspector general, NASA agreed to conform with US legislation enacted in 1988 that ordered all government departments to move towards the exclusive use of SI units.

Sad. What I don’t understand is:

In June 2006, when NASA’s progress on that looked sluggish, NASA spokesman David Steitz offered New Scientist this update: “NASA is in the process of converting to SI units. However, immediate conversion of systems that are already designed in English units can prove risky and inefficient. The US space program … will need time to evolve into SI units.”

[…] “Operating in space while using two different systems of measurement certainly opens the door for problematic mistakes and miscommunications,” he adds.

Why is it riskier to use inches and meters together than to use inches and yards together? In either case, you have to know what your units are in order for a number to mean anything. Mistaking inches for meters is no greater a problem than mistaking inches for yards.

Before DART’s launch, NASA found that GPS data on its position was mistakenly being read by its computer in feet. Ironically, correcting this to metres in a simulator resulted in an incorrect change to another parameter that was programmed into the spacecraft – a problem that led to the collision.

Oh, I get it. Someone is covering their ass by protecting against a previous mistake that had very little to do with SI vs imperial units but was played up that way by the media. Great…