Microgravity 101

Summary

What Is Microgravity? Microgravity is the condition where the force of gravity is not zero, but extremely small. Microgravity is typically between 1 thousandth and 1 millionth of Earth’s gravity. Despite what people say, the International Space Station isn’t in “zero-G”. It’s actually in microgravity. The astronauts feel weightless not because there’s no gravity, but because they’re in continuous freefall, orbiting the Earth at high speed. It’s like being on a roller coaster…forever. Why Does It Matter? In microgravity: Fluids don’t behave the same way (no convection, no sedimentation) Cells grow differently (cytoskeletons, morphology, gene expression) Combustion is strange (flames are spherical, oxygen diffuses differently) Crystals form more perfectly (used in pharma, protein crystallization) For scientists and engineers, this means: Microgravity is a unique experimental condition It can reveal behaviors masked by Earth gravity It can enable new classes of experiments, materials, and medicines Where It Shows Up in Space Platform Notes ISS Continuous microgravity (orbit = freefall) Parabolic Flights 20–30 seconds of microgravity per parabola Sounding Rockets Up to 5 minutes of microgravity CubeSats Short bursts (or passive microgravity if free-floating) Drop Towers Seconds of freefall in Earth-based facilities Common Misconceptions ❌ “There’s no gravity in space.” ✅ Gravity is always present. What you feel as “weightlessness” is actually freefall. ❌ “Microgravity and zero-G are the same.” ✅ Zero-G is idealized; microgravity is measurable (10⁻³G to 10⁻⁶G range). ❌ “Microgravity doesn’t affect experiments much.” ✅ It can profoundly change fluid behavior, biology, and crystal formation. How Spark Gravity Connects to This At Spark Gravity, we’re focused on programmable gravity. This includes 0G, partial-G, and full-G environments. Microgravity is one end of the spectrum, but most research today only happens in all-or-nothing environments: 0G on the ISS, or 1G on Earth....