A printer designed for space travel

HP’s ENVY ISS Printer, now orbiting Earth on the International Space Station, was engineered to perform in zero gravity.

By Garage Staff — May 10, 2018

Right now, there’s a printer spinning around the earth, some 250 nautical miles up in the sky on the International Space Station.

This printer is no ordinary device. The HP ENVY ISS Printer was built and tested (and tested and tested) specifically to perform in space.

Why? Because even in in this technology-driven era, on one of the most technologically sophisticated creations humans have ever engineered, NASA scientists know that in an emergency, printed instructions are a better bet than a computer every time. The ENVY ISS Printer is used to print out the protocols for emergencies so that the most updated versions, stored carefully in a binder, are always within arm’s reach. The astronauts also use the printer to make hard copies of their notes about the research projects they’re pursuing, so none of that irreplaceable data is lost.

The pull of paper

Still, even though the printer’s main job is serious business, it also performs other, more personal tasks for the astronauts, who print out photos sent by friends and family down on Earth — tokens of the anniversaries, birthdays and holidays the space travelers miss during their six-month stints.

“There’s something very human and psychological about the feel of paper,” Stephen Hunter, NASA’s manager for space station computer resources at Johnson Space Center, told CollectSPACE, the digital news source for space fans. "You get things that are very personal to the crew — letters from home, pictures. Some astronauts have used the printers to make keepsakes to bring home.”

The ENVY ISS shot into space in April 2, 2018 on the SpaceX Falcon 9 rocket, along with 5,800 pounds of other scientific gear. Now it’s starting to churn out its first assignments, ramping up to printing two reams of paper each month for tasks both technical and personal.

“It was a really great project,” says Ron Stephens, R&D manager for HP specialty printing systems. “We worked hand in hand with NASA, meeting with the astronauts to understand how we could help them with their mission.”  

So, what does it take to make a printer work in space?

Courtesy of HP

Gravity changes everything

About two years ago, NASA teamed up with HP, choosing HP’s OfficeJet 5740 printer as the base for new one it envisioned. After meeting with NASA engineers and astronauts to understand their needs, HP researchers went through every inch of the printer to ensure that it could meet the 20 different requirements NASA had laid out. First, they examined every step of the printer’s operation from a perspective we on Earth never consider: What if we can’t rely on gravity?

It was a once-in-a-lifetime assignment, say HP’s Stephens.

“It sounded simple: ‘Hey, we just need this printer to work in space,’” he says. “But when you start to look at what in your everyday life relies on gravity, there's so much that we take for granted.” For example, the part of the printer that holds the print cartridges hangs on a rod, on which it slides back and forth. It’s a pretty simple mechanical system — but one that depends on gravity to keep the cartridges and their carriage in place.

HP’s engineers had to reconsider each of the printer’s components, studying them and the way they worked to determine whether ink, paper or parts could float away, contaminating the space station and creating safety problems as well as rendering the printer inoperable.

They had to ask two questions about every component: Does it work in zero gravity? And is it safe in zero gravity? When the answer to either was no, HP’s researchers came up with new approaches, creating many new part prototypes using 3D printing to speed up the process.  

Focused function and fire-resistant plastic

“The key issue was containment,” says Gareth Kelly, HP’s lead systems engineer. “You definitely don’t want ink in the ISS becoming airborne or paper flying out through the printer into the space station and floating around.”

HP researchers examined every step of the printer’s operation from a perspective we on Earth never consider: What if we can’t rely on gravity?

To start, HP removed the scanning, fax and copy functions to reduce the printer’s weight and eliminate any glass that could break and then float around. The engineers also swapped out the printer’s regular plastic shell for one made of fire-retardant plastic.

To manage the ink, the team found the printhead didn’t require any changes, but they did note that during normal printing, some “extra” ink remains on the surface for a moment before drying. In space, those extra droplets would float away and disperse onto equipment or research projects. HP worked to prevent extra ink from being deposited in the first place and also added absorbent material nearby to catch any stray droplets, preventing them from contaminating the space station.

Cutting-edge 3D printing saves the day

Then came the paper. On Earth, we count on gravity to let us push a sheet of paper out of a printer and have it fall and stack. In space, that paper would fly away, explains Stephens. The earthbound solution would have been some kind of sheet-metal output tray. But that would introduce sharp, dangerous metal edges. HP’s team designed a special component using the HP Jet Fusion 3D printer, which transformed 11 parts and 18 nuts and bolts into one smooth, continuous part.  

And since the printer will be in space for years, HP’s engineers studied how they could make it more dependable. The team used material that the 3D printing group had developed, using microscopic glass beads encased in nylon, that makes the printer’s components extremely strong and durable.

The HP ENVY Printer was engineered for use in zero gravity on the International Space Station.

Courtesy of HP

The HP ENVY Printer was engineered for use in zero gravity on the International Space Station.

Three flights in zero G

To test early iterations in environments as close to zero gravity as possible, HP hung the printers upside down, at 45-degree angles and then spun them to see if the new parts would stop working or break or detach.

The final barrage of tests was the most spectacular, Kelly says. The printer and its engineers flew up in a test aircraft, affectionately known as a vomit comet, that makes parabolas around 10 times each flight, pulling 2Gs — twice the force of Earth’s gravity — to recreate the zero-gravity conditions needed. The NASA and HP testers made three flights over three days.

During the 20-second periods of weightlessness that this parabola produced at the top of the flight loop, the engineers madly tested their device, quickly printing pages to make sure the paper loaded, printed and came out as designed.

“When we went up and tested in the zero-G flight and saw all the design solutions work, we were very, very pleased,” says Kelly. “Experiencing the zero G was pretty awesome as well.”

Learn more about how the HP ENVY ISS Printers are taking on new frontiers.