Whether you’re an astrophysicist or a regular Joe viewing from your couch, there’s one thing that everyone has in common when watching SpaceX launch Starship after Starship.

And that thing is questions. Everyone has copious questions just waiting to be answered.

Will that rocket reach space? Why is that burner out? Will we all get to go in one of these someday?

And, in the case of one memorable Starship launch: why is a banana the only thing in the cargo hold?

SpaceX’s Dragon spacecraft have become a vessel of choice for delivering supplies to the International Space Station, joining the small list of organisations that send everything from food to essential hardware to the orbiting station and the astronauts living and working there.

Their flights have also become known for sending other things into space, including satellites, telescopes, and even a Tesla and a wheel of cheese.

So it’s understandable that people around the world were confused when footage from the Starship Flight 6 launch showed just a single banana inside the payload bay of the ship.

But, however quirky, the reason behind the banana launch is actually quite simple.

The banana – which was a toy banana, not a real fruit – was designed to help the SpaceX team understand the zero gravity conditions inside the bay.

In a SpaceX webcast of the Starship launch back in November, Kate Tice – a quality engineering manager at SpaceX – explained the significance of the toy fruit:

“Bananas have been used for quick visual comparisons for quite some time, and our teammates thought it was time to bring the venerated yellow fruit to Starship. Today, we’re flying Starship’s first-ever physical payload, which is, as you might have guessed, a banana.”

And it is that visual comparison element that explains why the banana plush – modelled on the typical, yellow Cavendish fruit – had the words ‘For Scale’ emblazoned on its side.

Tied securely to the cargo bay, the banana was both a fun and meaningful way for the team at SpaceX to demonstrate that their payload bay was safe and securely designed for the transportation of payloads into space. This humble banana will pave the way to more serious goods being transported, for everyone from private businesses to national governments, as Tice explained:

“You can see our stuffed banana payload, which is doubling as today’s zero gravity or zero-g indicator.

And while this payload will remain inside the vehicle at all times and will not be deployed today, it did give us a chance to do a test run of payload approval processes with the FAA, and that’s something that we’re hoping to do next year if we start flying our first Starlink satellites on Starship.”

Though the test flight did end up with a sea landing in the Gulf of Mexico, after its catch was aborted, the mission was deemed a success.

That’s because not only did the banana provide plenty of evidence for the zero-gravity tests, the team were also able to relight the engines while in space.

This crucial step lurches SpaceX forward in their plans for orbit and manned missions in the future.

If you think that’s impressive, check out this story about a “goldmine” of lithium that was found in the U.S. that could completely change the EV battery game.