NASA Put Spiders in Zero Gravity. Then Something Strange Happened.

Scientific concepts, discoveries, and nature phenomena

• Spider web construction as gravity-dependent behavior

  • Researchers investigated whether a spider can still build an organized web when the usual environmental cue—gravity (and its implied “up/down” reference)—is removed.
  • Spiders normally rely on gravity while building silk structures, which affects both positioning and orientation of the web.

• Microgravity effects on locomotion and web-building

  • In Skylab microgravity, Arabella initially had trouble moving and orienting, yet eventually began weaving.
  • Web development in orbit progressed from threads stretched across corners to a complete web with radial threads and spiral structure.

• Changes in web geometry and symmetry

  • In microgravity, webs showed reduced “directionality”:
    • On Earth, spider webs often have built-in asymmetry (top vs. bottom are not identical).
    • In microgravity, that distinction almost disappeared in Arabella’s most “correct cosmic web.”
  • This supported the idea that gravity helps spiders impose spatial structure.

• A behavioral and material consequence: silk morphology changes

  • Flight silk was reported as noticeably thinner than pre-launch silk.
  • The overall web structure also appeared altered compared with Earth-built webs.

• Microgravity does not eliminate environmental cues—other cues can substitute

  • Later International Space Station experiments suggested that light can become an important orientation cue when gravity is absent:
    • With lights on, some webs looked more “terrestrial,” with the web center shifted toward lamps.
    • Spiders tended to orient their bodies relative to light sources.
  • This reframes the original question from only “can spiders weave without gravity?” to:
    • What cue(s) replace gravity for organizing the web?

Key methodology / experimental approach (as described)

• Skylab (1973)

  • NASA sent two female orb-weaver spiders (known species) to Skylab:
    • Arabella (main)
    • Anita (substitute)
  • The crew placed spiders in a specially made cage/container and used lighting/cameras intended to document web-building.
  • Webs were eventually prepared for return to Earth and compared with expectations from terrestrial behavior.
  • Note: direct observation of one web-building event was limited because a camera button broke during earlier testing.

• International Space Station (later, “nearly four decades later”)

  • Researchers used a different spider species and ran a more controlled long-duration study:
    • Photographed webs every 5 minutes for almost 2 months
    • Compared with spiders kept in similar conditions on Earth

• Variable cue testing (light)

  • Web geometry differences depended on whether containment lights were turned on.
  • Spiders’ body orientation tended to align with the light source in microgravity.

Researchers / sources featured

• Owen Harriot (NASA astronaut; ran the Skylab spider experiment)
• Judith Miles (high school student; proposed the experiment after reading National Geographic)
• Peter Witt (scientist whose earlier spider-in-space ideas inspired Judith Miles)
• National Geographic (source Judith Miles read in 1971)
• NASA (space agency; designed equipment and conducted experiments)
• National Science Teachers Association (partner that invited student proposals)
• Researchers on the International Space Station experiment (named only generally; not individually listed in the subtitles)