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Why can’t people cry in space?

Crying is a very human reaction to emotions like sadness, pain, or stress. But in the microgravity environment of space, our tears don’t flow the same as they do on Earth. Astronauts have reported that tears stick to their face instead of falling. So why can’t people cry in space?

Tears rely on gravity

Tears start in our lacrimal glands, located above our eyes. These glands produce tears to coat, protect, and lubricate our eyes in normal conditions. When we cry in response to emotions, excess tears are produced that spill over our eyelids and run down our face. This is possible because of gravity pulling the tears down. In space, without the influence of gravity, tears don’t fall from our eyes but will rather stick to our skin. Astronauts have described having to wipe their eyes, otherwise the buildup of tears causes their vision to become blurry. So the act of crying works differently and our tears don’t flow or fall like they do on Earth.

Excess tears in space can cause issues

On Earth, the path our tears take helps us cry and removes the excess fluid from our eyes. In space, without gravity to pull tears down, excess tears build up and can cause issues. The tear film on our eyes is important for keeping our eyes moist and protecting them from debris. Too many tears can cause vision problems for astronauts. The tears can clump and form blobs that blur their vision or cause tears to spread across the eye, distorting vision. Astronauts have reported these effects during spaceflight. The lack of gravity also means that tears can’t drain through the nasolacrimal ducts that drain tears from our eyelids into the nose. This results in a buildup of tears across the eye and face.

Tears in space can create risks

The infamous footage of tears clinging to astronauts’ eyes highlights the strange behavior of tears without gravity. But excess tears sticking to an astronaut’s face can cause more serious issues as well. Here are some of the risks of excess tear buildup in space:

  • Can cause eye irritation and discomfort
  • Blurry vision that poses a risk during tasks like spacewalks
  • Potential risk of tears entering the nose and disrupting airflow
  • Tears and fluid buildup could increase risk of eye infections
  • Excess fluids on the skin could get into electronics and damage equipment

Astronauts have to take measures to manage eye and face wetness caused by tears in space. Simply wiping away tears prevents them from clumping and distorting vision. Some use eye drops to manage dry eyes that can result from excess tears spreading across the surface of the eye rather than falling down the face.

Crying as an emotional release is different in space

On Earth, crying helps us emotionally as well as physically. The act of crying can release emotions like sadness, relief, or joy. We feel better after “having a good cry” thanks to the physical shedding of tears. In space, astronauts still feel the emotions that lead to crying. But without falling tears, the physical and emotional release crying provides is reduced. Astronauts have to find different ways to express their emotions and relieve stress. Private audio/video calls allow them to share their feelings with family. Astronauts also reported using humor as an emotional release while in space.

Scientists study space tears

To better understand the behavior of tears in microgravity, scientists have studied it both in space and through methods of simulating microgravity on Earth. Research has examined tears under different conditions including:

  • Observing how tears from crying behave on astronauts in microgravity
  • Studying basal tears in microgravity environments
  • Looking at reflex tears produced in response to irritants in space
  • Using parabolic flight to create short bursts of microgravity
  • Having subjects lie tilted back to simulate the fluid shifts in microgravity

These studies verify that tears have altered dynamics in microgravity compared to normal gravity on Earth. The results help identify measures to manage vision and eye health for astronauts.

Key findings from scientific research on space tears

Research Finding Description
Tears are more watery The water content and volume of tears increases in microgravity.
Tears spread across the ocular surface Gravity isn’t pulling tears down the face, so they spread across the eye surface.
Tear drainage is impaired Tears have impaired drainage without gravity aiding drainage through the nasolacrimal ducts.
Eyelids aren’t as effective Microgravity changes eyelid positioning and blinking, making them less effective at distributing tears.
Vision can be temporarily altered Excess fluid and tear buildup were found to temporarily alter vision until wiped away.


In conclusion, the lack of gravity prevents tears from falling down the face as they do on Earth. Tears in space stick to the skin and build up, causing potential vision and health issues. Crying as an emotional release is also impacted, though astronauts can still feel the emotions leading to tears. Scientists continue to study the strange behavior of tears in microgravity to help astronauts manage eye and vision issues while living in space.