NASA cracked the Zero-G espresso problem

NEW YORK. KAZINFORM Just over a year ago, aboard the International Space Station 200 miles above earth, Italian astronaut Samantha Cristoforetti slid a plastic capsule into a machine about the size and shape of a home safe. She opened a small plexiglass door, attached a pouch of water to an intake valve, and snapped on a smaller, empty plastic bag. Then she closed the door, turned the machine on, and waited for her espresso.

We long ago solved the problem of making coffee on earth. But building an espresso machine for the space station turned out to be a much bigger challenge than the Italian engineering firm Argotec expected when it took on the project. A team of 11 engineers-7 of them working full time-spent a year and a half coming up with a brewing process that could work in microgravity and meet NASA's rigorous safety standards. "I don't think any of us realized that every component would have to be modified," says Joshua Hall, an engineer who worked on the project, named ISSpresso.

To make espresso, you have to force almost-boiling water through finely ground coffee beans. In a typical pot placed on your home stove, the water at the bottom becomes less dense, creating convection currents that mix the heat into the rest of the container. When the water boils, steam pushes into the air above. But hot water behaves differently in near-zero gravity; it doesn't rise. Even as it turns to steam, it stays put, close to the heating element. The result is a superheated, and dangerous, bubble of vapor suspended in a ball of water. Argotec's solution was to run the water through thin steel pipes to ensure that it never builds up bubbles of heat.

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