And in physics or engineering calculations where it really counts to keep those distinct, I do. But that has nothing to do with the question I answered. In doing so, I carried along the terminology used by Ed Cheng in his message, to which I replied. The Hubble weighs about 24000 lbs on Earth. That would be about 11000 kg.
All prefixes scale by powers of ten and so moving the decmal place makes scaling easy.
You can't do that, of course, with ounces and pounds. It is equal to 1000 kg, so you could say the HST weighs 11 metric tons. There is no ambiguity with that as there is between short tons and long tons. You are equating it to kilograms instead of the proper unit of newtons. Space craft should alwyas be quoted by their mass in kilograms.