Moon jellyfish

On April 12, 1961 cosmonaut Yuri Gagarin became the first person to go into space. Yet, like the first balloonists, the first earthlings in space weren't humans. Way back in 1783 the Montgolfier brothers tested their invention – the hot air balloon – by launching it with a sheep, a duck and a rooster as passengers. It landed safely, and the brothers were encouraged to develop their invention to fly with people on board. However, the first earthlings in space were to be even humbler creatures.

Drosophilas go to space
By the mid 20th century, hot air balloons were a curiosity, aircraft were in use, and space was the realm of telescopes and science fiction. However, some rockets developed for warfare became research rockets. The first space pioneers Drosophila melanogaster – commonly known as fruit flies – were launched from New Mexico on a V2 rocket. Scientists wanted to know how the strong radiation in space might affect their genetic material. The flies were successfully recovered alive, and their brief voyage hadn't caused any genetic damage.

First cosmonauts
With one exception, spaceflights before Gagarin were suborbital. A suborbital flight goes into space, but returns to Earth without orbiting. Gagarin wasn't the first earthling to orbit the Earth. The ill-fated dog Laika flew in Sputnik 2 in November 1957. She didn't survive, though a number of later canines later orbited and returned unharmed.

Spaceflight becomes common
By now, seven nations have launched non-human animals into space, and humans in space have become common. There have even been a few very wealthy space tourists, though only NASA's Apollo astronauts have actually voyaged to another heavenly body. There was a lot to learn about how microgravity affects humans, and we're still learning. Some of the knowledge was gained through the cooperation of astronauts and some through animal studies.

Moon jellyfish
Although two Russian tortoises went to the Moon in 1968, moon jellyfish have not. They get their name from their round white bodies. These jellyfish make for bizarre astronauts, being described as 95% water with no brain and very simple bodies.

When they're larvae, they're called polyps, and they have cilia to move around. Polyps mature into medusas and move when certain muscle cells pulsate. They swim to keep near the water's surface where they spread their tentacles to catch prey. Ocean currents move them around. So they aren' t much like humans, yet in June 1991 astronauts took some of them for a ride on the space shuttle Columbia. It was part of the first Spacelab Life Sciences Mission.

Why jellyfish in space?
The purpose of the experiment was to find out if space-born jellyfish would be able to respond to gravity. If there were to be interplanetary travel one day, this could be relevant to humans.

You may well wonder how this might relate to humans since we don't have a lot in common with jellyfish. But there is one thing. As the jelly grows, calcium sulfate crystals form surrounded by a small cell pocket coated in specialized hairs. These are the graviceptors, the organs that sense up and down by responding to gravity. The crystals roll to the bottom of the pocket. That moves the hairs, and they signal to the neurons in the jelly's nerve net. So although a jellyfish has no brain, these graviceptors do give them an effective way to orient themselves.

Humans also have structures rather like this. They allow us to sense up and down and the angle of our heads. They're located in our inner ears which contain both fluid and small crystals and hair cells. As we move, the crystals roll around and move the hair cells that send signals to the brain.

And what happened to the jellynauts?
Some of the jellyfish polyps went into space while others stayed on Earth as a control group. The polyps can reproduce asexually and they were induced to produce baby jellyfish. Astronauts in space and scientists on Earth then observed their development.

The jellyfish on the space shuttle seemed to develop normally and looked like their counterparts on Earth. But when they were taken back to Earth, the space-reared ones tended to have trouble telling up from down, so they moved awkwardly and had trouble getting around. Their graviceptors looked normal, so the researchers were unsure what was going wrong. One possibility was that they weren't correctly connected to the nervous system.

Colonizing space
Some people imagine colonizing other worlds or living in space. With over half a century of experience, we know a lot about what happens to humans in space. But what would happen to someone born in space?

The jellyfish experiment suggests that one possibility is that space-born children could suffer severe vertigo in the presence of gravity. However, I suspect that the difficulties relating to children born in space are unlikely to be a matter of concern for a long time, if ever.