From measuring one's mass to boosting the almost 1 million pounds (454,000 kilograms) that comprise the entire orbiting complex, the Expedition 73 crew aboard the International Space Station had a busy week in Earth orbit.

Orbital observation

It's a morning ritual for millions, but isn't so straightforward without the benefit of the pull of gravity.

"In space, we’re weightless, but not massless. So how do we measure our mass?" NASA astronaut Johnny Kim, a flight engineer on the space station's Expedition 73 crew, wrote in a social media post on Thursday (Nov. 20).

In short, it takes specialized equipment like Russia's Body Mass Measurement Device. They all, however, rely on Newton’s Second Law: F = ma.

"Apply a known force, measure the resulting acceleration, and you can calculate mas

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