In 1992, scientists sent 230 hornets into space to see if they could build a nest without gravity; after 8 days, they returned without building one

In September 1992, seven astronauts boarded the space shuttle Endeavour for an eight-day mission. Tucked into the shuttle's middeck was a much smaller, a bit unusual crew: 230 live hornets. In the official record of the STS-47 mission, NASA noted that the flight carried an experiment called ISAIAH, an acronym for Israeli Space Agency Investigation About Hornets. They wanted to know something simple but difficult to test on Earth: could the hornets build their famous honeycomb nests without gravity to guide them?

Reasons for choosing hornets for a space experiment

Oriental hornets are unusually skilled architects. Although the inside of the nest is pitch black, they build their nests from layers of hexagonal cells, arranged in remarkably straight, level rows. This makes them interesting to scientists studying gravity sensing in insects and physiologist Jacob Ishay of Tel Aviv University spent decades studying them on the ground. His previous work had already shown that hornets use gravity cues during construction. Spin their nest box in a centrifuge and the hornets adjust their combs to the new pulling forces. This raised a very obvious next question: what happens when all the gravity is gone?

What the mission actually carried into orbit

The official NASA mission report for STS-47 says the ISAIAH payload held 230 adult hornets and 120 pupae, the stage of development before the adult hornet emerges from its cocoon. The pupae were added so that scientists could also determine whether weightlessness might interfere with metamorphosis itself, not just with the building habits of adults.

What went wrong

The mission did not go smoothly. Early into the flight, a fault in the experiment's water system caused humidity inside the hornet habitat to climb far higher than planned, fogging up the container and putting the insects at risk. Mission specialist Jan Davis and pilot Curtis Brown worked around the problem mid-flight, rigging a hose from a spacesuit cooling fan to blow air into the habitat and clear the condensation. The same mission report notes the fix came too late for most of the colony. By the end of the mission, 202 of the 230 adult hornets had died and 103 of the 120 pupae had died as well. None of the surviving pupae completed metamorphosis to the adult stage.

Did the hornets manage to build a nest

Some of the hornets in the lower part of the container were still active on the seventh day of flight, but no new nest was built while the shuttle was in orbit. Those insects that did survive lived considerably shorter lives than the hornets kept as a ground-based control group. The experiment did not provide a clear answer to its original question, as the humidity failure made it difficult to distinguish the effects of microgravity from the effects of a damaged habitat.

Why gravity matters so much to hornets

A 1975 study on hornet nest architecture published in Nature titled ‘Hornet nest architecture’ explains why the experiment was worth attempting in the first place. The early studies by Ishay found that hornets rely extensively on gravity as a means of aligning the cells within their comb structures, even under complete darkness conditions. If the hornets rely so much on gravity on Earth, testing them in microgravity was a genuine way to probe how deep that dependency runs.

What a failed experiment still teaches us

A failed experiment is not a wasted experiment. The ISAIAH flight showed the challenge of keeping a live insect colony in routine operation outside of Earth’s environment and contributed to more than 50 years of research that call into question how living systems rely on gravity to develop and behave normally. Today scientists still send tiny organisms into orbit, from fruit flies to plant seedlings, to try to answer the same question, because the answers matter in terms of how humans might one day live and work away from Earth for extended periods of time. The hornets that flew on Endeavour in 1992 never finished building a nest, and most of them did not survive the trip. But their short, difficult flight is a reminder that some of science's most useful lessons can often come from experiments that do not go according to plan.