Three months before a single human was launched toward the Moon, two tortoises had already come back.

Sure, they didn’t get to make one giant leap for tortoise-kind on the surface. They just swung around the Moon.

But along with some much smaller critters, they were the first citizens of  Earth to get that far away from home! This was the USSR’s Zond 5 mission, and it was carried into space  by a funky-looking rocket. It’s called the Proton, and it was so successful that its descendents were used for over half a century! [Intro music] If you take a look at a Proton rocket, you might think that it looks a little funny near the bottom.

Especially in comparison to  other rockets of the era. The first stage of the rocket, meaning the part that holds  the first set of engines, has one big central tube surrounded  by a bunch of smaller ones. And you might think that those outer  tubes would be smaller boosters… separate rockets all coming  together to add more oomph.

But no. Those tubes are holding the Proton’s fuel. Meanwhile, the center tube  holds the second ingredient in making the rocket go up… or in worse cases blow up… the oxidizer that makes the fuel combust.

This arrangement was necessary because Proton had to be shipped  by train, lying on its side. So the central tube could only be so big. And interestingly, what was in those fuel tanks actually made the rocket pretty controversial, especially during its development.

All iterations of the Proton rocket, including the ones that sent  missions around the Moon, relied on a fuel called Unsymmetrical dimethylhydrazine, or UDMH. And it’s incredibly toxic. It’s so toxic that one of the USSR’s chief  rocket scientists didn’t want to use it.

But it did have some perks. For example, UDMH, as well as the oxidizer in  the Proton’s central tank, are hypergolic propellants,. That means that when you put them together, they’ll spontaneously ignite.

Since you don’t need something like a spark plug to set the reaction off, your rocket is at least a  tiny bit simpler in design. Having one less part that could  break is something worth aiming for. But perhaps the main benefit to UDMH was that it could be stored at room temperature, instead of needing to be kept super cold like most of the other rocket fuels on the market.

And a rocket that doesn’t need  its own fancy refrigeration system to keep its fuel from auto-igniting is a huge plus. That special hypergolic propellant combo was used for the three main  stages in every Proton rocket, whether it’s the classic Proton-K, or the more modern Proton-M. But some missions, like the ones that sent critters  around the Moon and back, needed a fourth stage added at the tippy top.

The Proton-K’s bonus bit of rocket, called Blok D, used a different fuel and oxidizer combo. So if you look up the Zond 5 mission, you’ll see the rocket that got  the job done called a Proton-KD. And sure, you’re probably looking it up to learn more about those tortoises, but Zond 5 racked up a lot of first place ribbons besides ferrying the first  Earthers around the Moon.

Earthers? Earthians? Terrans?

We probably need to settle  on an official name, soon. Whatever we call our tortoise  and non-tortoise travelers, Zond 5 didn’t technically get  them into orbit of the Moon. But on In September 1968, it became the first mission  to go around the Moon, period.

And it was also the first  mission to make it back to Earth after visiting another celestial body. Which I’m sure those tortoises appreciated. Now, you may be wondering, “Why tortoises?” To which I would say, “Well, why not tortoises?”.

But really, they were chosen  for a pretty practical reason. They were easy to strap down. The critters were basically kept in very small cages that  didn’t allow them to move.

So no floating around, experiencing the joys of microgravity. Which is a huge bummer. It was also a huge bummer for  the control group of tortoises kept in the same caged conditions back on Earth to figure out the  biological consequences of spaceflight.

Because the flight was short enough, none of the tortoises involved in this experiment had any food or water during the journey, or weeks on either side of the journey. But the ones that got to go  to space at least had company. Zond 5 was a veritable ark, containing fruit fly eggs, meal  worms, seeds, and bacteria.

The researchers even reportedly  sent human cells along for the ride, to see what space would do to them. But if we’re being honest, we all know the tortoises  were the stars of the show. And happily, they returned to  Earth in fairly good health.

They did lose about 10% of their body weight, which was about twice the amount lost  by the tortoises in the control group. In other words, it wasn’t just because they weren’t allowed to eat  or drink anything up there. But then again, this is only two tortoises, so it’s not exactly a definitive insight into what space travel does to a body.

There were some other side effects, but the research team attributed most of them to starvation,  rather than space flight. And that’s a good thing,  because it suggested humans would be a-ok to make a similar journey, so long as they were properly fed and watered. Of course, Apollo 8 would soon  prove this on the US side of things, going around the Moon and  telling the world Merry Christmas just a few months after Zond 5 had  splashed down in the Indian Ocean.

And a few years later, animals and astronauts would share a ride to the Moon. In 1972, five mice named  Fe, Fi, Fo, Fum, and Phooey orbited the Moon during the Apollo 17 mission. Unfortunately, our tortoise record-holders  don’t seem to have had names.

So if you want, you can leave a  comment below sharing what names you think they should be  given, over five decades later. Maybe there are a couple of  lesser-known Renaissance artist s that need a shoutout. Unfortunately, these tortoise cosmonauts had a bit of a downer ending, getting dissected to figure  out how safe space travel would be for human cosmonauts.

But there is a happier note we can finish on. A few more Protons ferried  missions around the Moon and back, carrying even more animals. And while this class of rockets never  got to take a human to the Moon, the Proton-K did launch the  first two Russian modules of the International Space Station.

Which humans have occupied  continuously since 2000. For over half a century, the  Proton-K and its successor, the Proton-M, were proper  workhorses of the Soviet, and later Russian, fleet of space launch systems. But as of 2023, they are  reportedly being phased out.

Partly due to competition from  private companies like SpaceX. Partly due to the fact that they’re still  using that extra toxic hypergolic fuel. But even though it’s probably on its last legs, the Proton rocket will always be remembered for ensuring that tortoises definitely beat both hares and humans in the race to the Moon.

And what better way is there to remember a historic space mission  than turning it into a pin? This month, you can head on  over to DFTBA.com/SciShow to order your very own shiny, miniature Proton rocket, joined by some adorable tortoises you can name. I’m gonna call mine Bert and Ernie.

And Bert and Ernie say thanks for watching. [ outro ]