September 15, 2021

— As the second stage engine of SpaceX's Falcon 9 rocket cut off, Hayley Arceneaux reached into a pouch strapped to her leg and pulled out a plush doll.

She then let it go.

The toy, attached to a tether, began to float above Arceneaux's head and in doing so, fulfilled its purpose as the Inspiration4 mission's "zero-g indicator." Hanging in the air, it provided a visual signal to Arceneaux and her three crewmates that they were now in the microgravity environment of outer space.

"We can see the zero-g indicator floating around," Andy Tran, a SpaceX quality engineer, said on the live webcast of the launch on Wednesday (Sept. 15).

"And it looks like it is a little golden retriever," senior certification engineer Kate Tice said.

"Like the golden retriever assistance dogs at St. Jude's Children's [Research] Hospital. That is apropos," Jessie Anderson, a SpaceX production and engineer manager, chimed in.

Inspiration4 zero-g indicator. Click to enlarge and view video in a pop-up window. (SpaceX)

Almost simultaneously back down on Earth, St. Jude's launched the plush puppy's secondary mission — to inspire people to give.

"Inspiration4 has reached zero gravity and unleashed their zero gravity indicator!" the hospital announced on Twitter. "Check out our gift shop to get your own space buddy dog plush."

Underwritten by billionaire and mission commander Jared Isaacman, Inspiration4 aims to be St. Jude's largest fundraiser, bringing in $200 million to advance pediatric cancer research. Isaacman donated the first $100 million and has used the spaceflight — with its "all-civilian" crew, including medical officer Arceneaux, a cancer survivor and physician's assistant at St. Jude's — to encourage the public to donate, too.

The tradition of flying zero-g indicators began in Russia, inspired by the world's first person to fly into space. Yuri Gagarin carried a small doll with him on his Vostok 1 mission in 1961. Later cosmonauts launched with stuffed toys, often at the choice of their children, and hung them from their spacecraft control panels.

SpaceX adopted the custom with its first flight of a Crew Dragon capsule to the International Space Station. Past SpaceX zero-g indicators have included a Celestial Buddies' plush Earth, a Ty sequined dinosaur named "Tremor," a Star Wars Grogu (or "baby Yoda") and a Jellycat "My First Penguin" named by its crew "GuinGuin."

The Inspiration4 zero-g indicator may be the first in history, though, to be used to raise funds for a cause.

"Celebrate the first all-civilian mission to space with this adorable replica," St. Jude's wrote on its gift shop's listing for the Inspiration4 zero gravity indicator replica. "Lovingly named Jude, this plush is wearing its St. Jude space suit and is ready to take your imagination to the stars."

The "extra-soft plush" was modeled after the hospital's facility dogs, Puggle and Huckleberry. Since September 2019, the two specially-trained golden retrievers have worked with St. Jude patients to "help them meet clinical goals, easing fears and calming patients during challenging situations."

Sales of the 15-inch (38-cm) Gund doll support St. Jude's life-saving research and care. The replica space puppies cost $24 each.

Within three hours of the Inspiration4 launch, the first batch of dolls were sold out.

"Due to an amazing response to the Inspiration4 launch, we are currently sold out of the Inspiration4 Zero Gravity Indicator Replica Space Puppy. More are on the way Sept. 27th!" St. Jude's gift shop posted to its website.

The Inspiration4 crew, including Isaacman, Arceneaux, pilot Sian Proctor and mission specialist Chris Sembroski, packed their SpaceX Dragon with memorabilia to auction for St. Jude's. The mission will orbit Earth for the next three days and then return to a splashdown off the coast of Florida.