January 18, 2022 | David F. Coppedge

Astronauts Lose Red Blood Cells

The human body is designed for Earth, not Star Trek.
The longer the time in space, the worse the anemia.


Two million per second. That’s the rate at which a human body on earth destroys and makes red blood cells (RBC). In space, however, the destruction rate is 54% higher: 3 million RBCs are destroyed per second. That’s out of about 20-30 trillion RBCs in the body at equilibrium. Scientists at the University of Ottawa determined these numbers from blood samples from 14 astronauts returning to earth after six months in space.

It’s been known that long tours in space have deleterious effects on astronauts. Despite the happy grins of space travelers enjoying weightlessness, turning somersaults and playing tricks with floating food, each second takes a small toll on the body. Those seconds add up. After lengthy stays in the International Space Station (ISS), astronauts need time to readjust to earth gravity. Videos show astronauts unable to stand to their feet Five of 13 astronauts were clinically anemic when they landed.

“Thankfully, having fewer red blood cells in space isn’t a problem when your body is weightless,” said Dr. Trudel. “But when landing on Earth and potentially on other planets or moons, anemia affecting your energy, endurance, and strength can threaten mission objectives. The effects of anemia are only felt once you land, and must deal with gravity again.”

What Happens to the Blood in Weightlessness?

Space anemia has been known for years. Early research on weightlessness suggested it was temporary, and that equilibrium was reached when fluids in the body adjusted to the new environment.

Before this study, space anemia was thought to be a quick adaptation to fluids shifting into the astronaut’s upper body when they first arrived in space. Astronauts lose 10 percent of the liquid in their blood vessels this way. It was thought astronauts rapidly destroyed 10 percent of their red blood cells to restore the balance, and that red blood cell control was back to normal after 10 days in space.

The new research shows that some affects of space anemia are long lasting. The primary effect is an increase in destruction of RBCs. A 54% increase in the destruction rate (measured by amount of carbon monoxide in the blood, created when the heme molecules of RBCs are destroyed) continues throughout the flight. The blood does not recover immediately. In some astronauts the RBC destruction rate was still 30% above normal a year after their flight. The team said, “it’s unclear how long the body can maintain this higher rate of destruction and production of red blood cells.”

Elon Musk’s roadster launch was only a publicity stunt. The harsh realities of space have already made quick work of the car and mannequin driver. Credit: SpaceX, via BBC News.

Implications of the Study

The world record single space flight was set in 1995 by cosmonaut Valery Polyakov: 438 days (14 months). Dozens of others have racked up more time in space over multiple flights; that, however, gave their bodies time to recover between flights. The missions to Mars envisioned by NASA and by futurist entrepreneur Elon Musk would take about 3 years nonstop. Blood loss becomes a serious concern for such lengthy flights. It could rob astronauts of ability to work, think, and fulfill their mission objectives.

The discovery that space travel increases red blood cell destruction has several implications. First, it supports screening astronauts or space tourists for existing blood or health conditions that are affected by anemia. Second, a recent study by Dr. Trudel’s team found that the longer the space mission, the worse the anemia, which could impact long missions to the Moon and Mars. Third, increased red blood cell production will require an adapted diet for astronauts.

No air to breathe on Mars, too.

Dr Guy Trudel, a rehabilitation physician on the U Ottawa team, knows that prolonged bed rest in hospitals also causes anemia, perhaps for similar reasons. What this means is that astronauts on long-term missions to the moon (with 1/6th Earth gravity) and Mars (with 3/8th Earth gravity) would not get enough of a gravity “fix” to significantly reduce the risk of anemia. It also implies that people down home on Earth need physical activity for good blood health.

The U Ottawa team does not rule out future ways of preventing anemia with diet and yet-undiscovered treatments. Their findings, however, were surprising to them.

“This is the best description we have of red blood cell control in space and after return to Earth,” said Dr. Trudel. “These findings are spectacular, considering these measurements had never been made before and we had no idea if we were going to find anything. We were surprised and rewarded for our curiosity.”

Getting Real

Sci-Fi novels and movies such as 2001: A Space Odyssey have portrayed artificial gravity produced by rotating the ship. The cost required for such a craft, though, with all the massive parts needed to launch, build and power a rotating ship—let alone to send it across distances in space—appears far off. Certainly human bodies could not tolerate visiting distant worlds in Star-Trek style ships. Those portrayals were made safely in Earth gravity in studios in Burbank, California.

A Star Trek movie with Spock and Captain Kirk beamed down to a planet, only to collapse in pain, unable to stand and face the attacking aliens, would probably not get good reviews. William Shatner (who played Kirk) got his first taste of the realities of space flight last October 13, and was overwhelmed (Space.com). He confessed, “I had no idea.”

We see again that the human body is intimately tied into the Earth environment – its gravity, its atmosphere, and its food and mineral resources. Leave our tiny cocoon, and the body goes downhill in far less time than available to establish a presence elsewhere.

“Reaching for the Stars” by Apollo 12 astronaut Alan Bean. Used by permission.

Our minds and spirits, however, are unfettered when dreaming of distant worlds. In a real way, we long for them. Where do our spirits go after death? The Bible speaks much of heaven and hell. The souls of martyred saints still cry out to God for justice (Revelation 6:9-10). Where are they at that time? My opinion is that they are not far off in space, but rather in some dimension of reality we cannot experience in our current mortal bodies. Think of how the concept of a 3rd spatial dimension would be unimaginable to inhabitants of Flatland (a 2-dimensional reality).

In this view, when the New Jerusalem “comes down out of heaven from God” (Revelation 21:2), it is not traveling through outer space and crash-landing under Earth gravity; it would be coming out of an extra (but very real) dimension, where it already is, becoming visible in our 3-D world. There will be a new Earth as real as this one, but its inhabitants will have access to the New Heaven where God’s throne is. Our resurrected bodies will be like those of Christ, able to move about locations in an instant, analogous to how an inhabitant of Spaceland could visit any spot in Flatland. The Creator who fit our bodies to this reality will provide bodies fit to the New Earth – no more to suffer tears, disease and death.

An unrealistic depiction of the New Jerusalem coming down out of heaven, IMO.

Just because we cannot now experience such a thing, we already know that unseen realities are possible. Right now there are people speaking inside our heads, but we cannot experience them without a TV or radio tuned to them. Whatever the future New Earth is like, we have the assurance from the Creator himself of a great divide that will separate the forgiven from the unforgiven:

And he who was seated on the throne said, “Behold, I am making all things new.” Also he said, “Write this down, for these words are trustworthy and true.” And he said to me, “It is done! I am the Alpha and the Omega, the beginning and the end. To the thirsty I will give from the spring of the water of life without payment. The one who conquers will have this heritage, and I will be his God and he will be my son. But as for the cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars, their portion will be in the lake that burns with fire and sulfur, which is the second death.” (Revelation 21:5-8).

Will you be among those enjoying the joy of the Lord forever, instead of His wrath at sin? The latter is the default for sinners on our rebellious planet, but anyone can be forgiven and enter God’s grace freely. The last invitation in the Bible goes like this: “The Spirit and the Bride say, ‘Come.’ And let the one who hears say, ‘Come.’ And let the one who is thirsty come; let the one who desires take the water of life without price.” (Revelation 22:17).

Shatner remarked, “Oh my god, what an experience” after seeing the Earth from space. Let’s pray he has a God: the one true God. Follow our Site Map to the gate of the narrow way that Jesus said is the way of life. Jesus calls everyone to “Come.” You can do it right now.

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