"You can't just send a regular espresso machine to orbit and expect it to work," she says. Here on Earth, coffee machines depend heavily on gravity, she explains. But on the ISS, there's only a minuscule amount of gravity — called microgravity. So everything floats.

The biggest challenge is figuring out how to keep the scalding water inside the espresso machine contained, Kloeris says. Everything has to be sealed, secure and safe.

How the ISSpresso system works. Infographic: Courtesy of Lavazza

There's also the issue of keeping everything sanitary. "On the ISS, they don't have a sink where they can wash everything up," she says. A small amount of liquid left over in the machine could become rank and unhealthful pretty quickly.

But once these safety concerns are addressed, there's the whole issue of making sure the espresso tastes good. And that where it gets really tricky, says David Avino at Agrotec, who helped develop the ISSpresso.

"To make good Italian espresso there are two major components — the pressure and the temperature," Avino says. Water has to approach the coffee grounds at around 98 Centigrade (208 Fahrenheit), and leave the brewing unit at 75 C (167 F), Avino says. Fluctuations in the temperature of either the water or the steam can leave you with a substandard brew.

But the balance is really hard to achieve in space. When you boil water on Earth, the bubbles of steam stay evenly distributed in the water because of gravity. In space, these bubbles can come together and create pockets of really hot air.

That can really mess with the temperatures inside the espresso machine, Avino says. It can also get dangerously hot.

The engineers behind the ISSpresso got around this by using sturdy steel tubes to move the water around, instead of the rubber tubes used in regular espresso machines. They also equipped it with various temperature controls.

These extra bells and whistles make the ISSpresso weigh over 40 pounds, according to Avino. The plan is to send the machine up to the ISS with Italian astronaut Samantha Cristoforetti next year.

Initially, the machine will come with only 20 single-serve coffee capsules. "Our machine is still an experiment," Avino says. If all goes well, he says, the machine could become a permanent addition to the space station.

Of course, drinking coffee up in space still won't be the same as sipping it down here on Earth. Classic Italian espresso comes with a creamy layer of foam on top. But that foam may behave a lot differently in space, Avino says. "It will most likely spread around the whole container."

And the astronauts will have to drink it out of a sippy pouch so the hot liquid doesn't float away from them. It's not quite as elegant as drinking from an espresso cup.

It also means the astronauts won't be able to smell the coffee very well, Avino says. And smell has a huge impact on the way we perceive food and drink.

But hopefully, it will be an improvement over the instant coffee that the astronauts have been drinking thus far. With a shot of sharp espresso to start the day, Avino says, "they'll live much, much better."

Copyright 2014 NPR.

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