Asger Risom
In 1990, NASA sent about 2,000 baby jellyfish into space to study how organisms develop in microgravity. When the mission returned to Earth nine days later, more than 60,000 jellyfish had grown — but many struggled to adapt to gravity again.
In 1990, NASA carried out an unusual experiment that involved sending thousands of baby jellyfish into space. The goal was to study how living organisms develop in microgravity — and what that might mean for humans born beyond Earth.
The experiment began with roughly 2,000 jellyfish polyps, an early stage in the jellyfish life cycle.
They were sent aboard the Space Shuttle Columbia in bags filled with artificial seawater. Over the course of the mission, researchers monitored how they developed in the near-weightless environment of space.
By the time the spacecraft returned to Earth about nine days later, the tiny polyps had multiplied dramatically. Scientists found that more than 60,000 jellyfish had grown during the mission.
Why NASA chose jellyfish
At first glance, jellyfish might seem like an unusual choice for a space experiment about human biology. However, they share one important trait with humans: both rely on gravity to understand orientation.
Humans use the vestibular system in the inner ear to sense which way is up and to maintain balance. Jellyfish use specialized structures called statoliths in their bodies to detect gravity and orient themselves in the water.
Because of this similarity, scientists believed jellyfish could help them study how organisms develop a sense of direction in environments where gravity is extremely weak.
What happened when they returned to Earth
The jellyfish successfully developed in space, but researchers noticed something unexpected after they came back to Earth.
Unlike jellyfish raised on the ground, the ones that grew in microgravity struggled to swim normally. Scientists observed irregular movements and what they described as abnormal pulsing behavior.
The findings suggested the animals were experiencing something similar to severe vertigo — difficulty adjusting to Earth’s gravity after developing in space.
What the experiment could mean for humans
The results raised important questions about what might happen if humans were born and raised in space or on long missions far from Earth.
If organisms develop their balance systems in microgravity, returning to a stronger gravitational environment might be difficult. The jellyfish experiment suggested that biological systems responsible for orientation may depend heavily on early exposure to gravity.
While humans and jellyfish are obviously very different, the experiment provided one of the early clues that growing up in space could lead to unexpected challenges when adapting to life on Earth.
Sources: NASA
