If this NASA launch vehicle could talk — say at an international consortium of the world's most elite, hobnobbing space rockets — this is how it would introduce itself after filling out its "Hello, my name is" sticker:

Space Launch System? Bleh, only my mother and technical manuals call me that.

SLS? Not since grade school.

Please, friends call me Moon Rocket. Mega Moon Rocket.

Technically, this gargantuan is the U.S. space agency's Space Launch System or SLS for short. But somewhere along the line, the mission crew stopped calling it by its given name and started referring to it by its badder, Transformers-ish nickname. Even the news releases from the agency use it now.

When asked recently who was responsible for coining it, though, the agency wasn't really sure.

Maybe the PR folks? Reporters?

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"I don't think it's an official thing, so hopefully we haven't gotten in trouble by using it," said Tom Whitmeyer, deputy associate administrator for common exploration systems development, during a call with reporters in April. "I like it because it's a good way to talk about the rocket. It is a really big rocket."

The rocket will hoist NASA's new Orion spacecraft on the maiden voyage of Artemis, a program aimed at proving the vehicles are safe for sending humans into deep space and back. No one will be inside the spacecraft this time, but if the flight is a success, it will clear the way for future missions carrying astronauts, including the first crewed expedition to Mars.

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Some numbers to give a sense of just how mega Mega is:

• 6 things to know about NASA's moon-bound megarocket
• NASA's monstrous moon rocket is an overpriced, political beast
• NASA astronauts on Artemis could talk to a spaceship computer
• NASA just revealed the wild spots it'll land astronauts on the moon
• Why landing a spaceship on the moon is still so challenging

• 5.75 million pounds

• 322-feet tall

• 8.8 million pounds of maximum rocket thrust

Artemis I will zoom around the moon, then splash down in the Pacific Ocean in October. Over the course of six weeks, it will demonstrate the equipment's ability to fly various orbits and safely reenter Earth's atmosphere.

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NASA encountered some problems with the rocket this spring during dress rehearsals, involving bad valves, faulty fans, and leaks. Whitmeyer said those come with Mega's territory.

"That's the kind of challenge you only see with something like a mega moon rocket," Whitmeyer said. "I don't think you kind of see those types of challenges with a rocket that's not that size."

Regardless of who gave Moon Rocket — Mega Moon Rocket— its nickname, it appears to be around for the long haul.

"We thought we'd just go and run with it," Whitmeyer said.