If NASA does find signs of life on its upcoming mission to Jupiter's orbit, the space agency wants to make sure that whatever's out there knows about us too.

So NASA is etching a poem onto the side of the spacecraft due to launch next year. Its author, Ada Limón, the U.S. Poet Laureate, said in an interview with Morning Edition that writing this particular poem was one of her hardest assignments.

"When NASA contacted me and asked me if I would write an original poem, I immediately got really excited and said yes. And then we hung up the call and I thought, 'How am I going to do that?'" Limón said.

She said it was difficult to think of what to write for a 1.8 billion mile journey. The vast distance to Europa means that the spacecraft won't reach its destination until 2030, which is six years after its launch.

NASA's Europa Clipper mission aims to learn more about whether the icy moon has the ingredients necessary to sustain life. The spacecraft will fly by Europa about 50 times and send back data, which NASA hopes will include clues to one the universe's greatest mysteries: Are we alone?

Limón found inspiration for the poem, "In Praise of Mystery: A Poem for Europa" which she unveiled at a reading at the Library of Congress on June 1, here on Earth.

"The way I finally entered the poem was to point back to the earth," Limón said. "The outreaching that the poem was doing was just as important as pointing back to the beauty and power and urgency of our own planet."

Limón writes of the "mysteries below our sky: the whale song, the songbird singing its call in the bough of a wind-shaken tree." One common element of our natural world, water, is a critical part of this mission.

Scientists believe water sits under a shell of ice on Europa, giving the moon one of three elements needed to sustain life. They also want to know more about Europa's water, and whether the moon could house the two other building blocks of life — organic molecules and food — said Laurie Leshin, director of NASA's Jet Propulsion Laboratory, overseeing the spacecraft's construction.

"Europa is an ocean world like the Earth, right?" Leshin explained. "Our ocean is teeming with life. The question is: are other ocean worlds also teeming with life?"

When Limón was first briefed on the mission, she jotted down an idea: "We, too, are made of water." That same line made it into the poem, which she ends this way:

"O second moon, we, too, are made

of water, of vast and beckoning seas.

We, too, are made of wonders, of great

and ordinary loves, of small invisible worlds, of a need to call out through the dark."

The full poem will be engraved on the side of the spacecraft in her own handwriting — she had to write it down 19 times until she was satisfied with the final copy.

You, too, can make yourself known to Europa by attaching your name to this poem. But you won't need to worry about your handwriting. As part of the "Message in a Bottle" campaign, all names received will be engraved on a microchip that will fly in the spacecraft towards Europa.

The digital version of this story was edited by Majd Al-Waheidi.