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Do bodies decay in space?

Whether or not human bodies decay in outer space is a fascinating question. As more and more people travel to space, it’s important to understand how our bodies react in the extreme environment beyond Earth’s atmosphere.

Quick Answer

In short, yes – human bodies still decay in the vacuum of space, but the process is much slower than on Earth. Decay may even be halted almost completely if the body has any kind of protection from solar radiation.

How Do Bodies Decay on Earth?

To understand how decay may happen differently in space, first let’s review the process on Earth. When a person dies, the heart stops beating and blood circulation halts. Cells begin to rapidly degenerate, especially without oxygen being circulated by the blood. Bacteria and enzymes start breaking down body tissues within minutes.

The first visible signs of decay include paleness of the skin and cooling of the body to room temperature. Rigor mortis sets in within a few hours as muscles stiffen. Over the next few days, the body turns a greenish-black color as decomposition spreads. Inside the body, organs and tissues liquefy into a mass known as “putrefaction.”

Within a week, bloating of the abdomen occurs due to gases released by bacteria inside the body cavity. At this point, skin blisters open to reveal the decaying tissues underneath. Strong odors are released as the major organs break down. After several weeks, hair, nails, and teeth loosen as skin and muscle tissues deteriorate.

Eventually only the bones and a few connective tissues remain. Full skeletonization can take one to three years depending on temperature, humidity, and accessibility of the body to insects. On Earth, the primary drivers of decay are moisture, ambient temperature, and insects and bacteria that consume the tissues.

Factors Affecting Decay in Space

Several key factors make space very different than Earth when it comes to decomposition of human bodies:

  • Lack of oxygen – Space is essentially a vacuum, providing no free oxygen for aerobic bacteria.
  • Extreme cold – Bodies not protected from space exposure will reach temperatures near absolute zero.
  • No insects or scavengers – Bacteria are the only potential decomposers.
  • Intense radiation – Solar radiation can kill bacteria and degrade organic matter.
  • Dryness – Without moisture, mummification may occur before decay.

Let’s look at how each of these factors may slow down or prevent decay:

Lack of Oxygen

The human body hosts a wide variety of bacteria that begin decomposition immediately after death. Many of these bacteria are aerobes, meaning they require free oxygen. Without oxygen, their growth and food production are severely limited.

Anaerobic bacteria that don’t need oxygen can still break down some tissue, but at a much slower rate. Overall decay is dramatically slowed by the lack of aerobic decomposition.

Extreme Cold

Temperatures in space range from -270°C in deep space to 121°C on a spacecraft exposed to direct sunlight. At very cold temperatures approaching absolute zero, chemical reactions, bacterial metabolism, and decay processes grind nearly to a halt.

Cold alone helps preserve dead tissue. Food and bodies kept frozen can remain intact for centuries. In space, extreme cold drastically slows the normal pace of decomposition.

No Insects or Scavengers

Insects are major decomposers on Earth. Flies and maggots consume decaying flesh and speed up the process. Ants, beetles, and other scavengers quickly dismantle and bury bodies.

In space, there are no insect colonizers to spread bacteria, consume tissue, or dismantle remains. This leaves only the bacteria accompanying the body as the primary decomposing agents.

Intense Radiation

Solar radiation and cosmic radiation in space can penetrate the body much deeper than on Earth. Radiation can kill bacteria and degrade cell structures, essentially “burning” the body from the inside out.

If the radiation dose is high enough, it can destroy a body faster than the bacteria can decay it. High radiation plus cold is essentially like freeze-drying the remains.


On Earth, moisture is essential for decay. Bacteria need water environments to grow and spread. Drying out a body can essentially halt decay as seen with mummification.

The vacuum of space desiccates any unprotected body. Without moisture, bacterial activity and decomposition shut down. The body is left perfectly preserved in a dry, sterile environment.

Evidence of Decay in Space

We have limited evidence about decay of human bodies exposed to the open space environment. Small animals have been placed outside spacecraft to study what happens. Let’s look at what we’ve observed so far:

Animal Experiments

Several capsule experiments have exposed animal remains to space. These give some clues about how human bodies may react:

  • 1960s – USSR space dogs remains showed drying and preservation of tissue.
  • 1997 – An American shuttle mission exposed rat carcasses, which completely mummified.
  • 2008 – Mice outside the ISS for 90 days suffered little decay due to radiation and freezing.

Overall, these experiments showed very slow decay and good preservation of animal flesh in space for short periods of time.

Human Space Disasters

A few tragic accidents provide insight about human bodies exposed to space:

  • 1961 – USSR cosmonaut Vladimir Komarov’s remains were primarily skeletal after his capsule crashed back to Earth.
  • 1971 – USSR cosmonauts on Soyuz 11 were found bleached and desiccated inside their capsule after it depressurized during descent.
  • 1986 – Challenger crew remains showed minimal deterioration after being recovered from ocean crash.

These real human cases suggest bodies can persist intact for some time in space and during Earth re-entry. However, the state of remains ultimately depends on the conditions of exposure.

Deliberate Space Burials

A few people have chosen to have their ashes launched into space after cremation:

  • 1992 – NASA engineer Eugene Shoemaker’s ashes carried to the moon on the Lunar Prospector.
  • 1997 – LSD pioneer Timothy Leary’s ashes rode a rocket into orbit.
  • 2007 – Star Trek actor James Doohan’s ashes briefly orbited Earth before reentry.

Obviously ashes and bone fragments will persist unchanged floating through space. But these cases don’t reveal much about how intact bodies would decay.

Space Cemetery Plans

Several companies offer future space burials, planning to launch cremated remains:

  • Elysium Space plans a memorial capsule in orbit taking cremains from paying customers.
  • Ascending Memories will offer rocket launches of ashes to remain in space.
  • Celestis Memorial Spaceflights launched some ashes into deep space in 1997.

While families may memorialize loved ones this way, cremated remains will not decompose or demonstrate decay processes in space.

Can a Body Not Decay in Space?

For an intact body exposed to open space, some level of decay will certainly occur. However, the right conditions could preserve human remains for hundreds or thousands of years:

  • Sub-zero temperatures could halt most bacterial activity and cell breakdown.
  • No moisture prevents decay and leads to mummification.
  • Radiation bombardment could sterilize the outside of the body.

NASA and the military have studied how to best preserve human bodies in space for later recovery. Techniques like wrapping the body in plastic and cold storage would help prevent decay.

Factors That Increase Decay

Some conditions could lead to faster breakdown of remains in space:

  • Warmer temperatures increase microbial metabolism and cell breakdown.
  • Moist environments allow bacteria to spread and grow.
  • Radiation exposure is less if shielded, allowing bacteria to degrade tissues.
  • Traumatic injuries like burns or gas bubbles provide starting points for decay.

For example, a body exposed to only deep space away from a star may freeze-dry. But one left on a warm, sunlit spacecraft surface could decay rapidly.

Putrefaction Gas Effects

One issue around decay in space is build up of putrefaction gases inside the body – methane, hydrogen sulfide, ammonia, and others produced as soft tissues break down. Over time, this build up could:

  • Bloat the body.
  • Rupture the skin.
  • Propel the remains into motion.

Escaping gases and thrown bodies could present issues around manned spacecraft. Microgravity makes containing the spreading gases difficult. Adequate body storage and ventilation are needed.

Long-Term Persistence

How long could an intact body last in space? Here are some estimates for time scales of preservation:

  • Days to weeks – Without protective preparation, decay and putrefaction will proceed rapidly.
  • Weeks to months – Natural mummification and freeze-drying slows deterioration.
  • Years – Optimal cold storage with radiation shielding preserves remains for transport.
  • Hundreds of years – Some experts think a frozen, irradiated body could persist intact for centuries.

Deliberately seeking to avoid decay, as with cremation ashes, a body could float undisturbed in space for millennia.

Hazards of Decay

Decay of human bodies presents some health and safety concerns for current and future space programs:

  • Bacteria – Billions of hardy bacteria remain infectious after host death.
  • Toxins – Decay releases dangerous biological compounds.
  • Biohazard – Free-floating body parts and fluids present contamination issues.
  • Mental Health – Crew member deaths and floating remains are psychologically hazardous.

Protocols are still being developed to properly handle human fatalities in space. This will be critical for future long-term missions and space settlements.


While no full human bodies have been studied long-term in space, evidence suggests decay will proceed slowly due to lack of oxygen, extreme temperatures, dryness, and radiation exposure. Minimal decomposition could allow bodies to persist for hundreds of years if shielded and stored appropriately. However, accelerated decay is still possible under certain conditions. Understanding how remains break down in space will be vital for far-reaching space exploration.