We all dream of journeying (or living) among the stars. But space is a spectacularly awful place for humans, and we’re not suited for life there at all. And yet, it doesn’t have to be that way. Here are all the ways we’ll need to re-engineer the human body, in order to make space our home.


In the six decades that we’ve been sending humans into space, scientists have learned just how truly bad it is for us to live off-planet.

Long-term exposure to microgravity is particularly nasty, causing dramatic losses in bone density (spaceflight osteopenia) and muscle mass (spaceflight sarcopenia and even outright atrophy). Low gravity also causes a release of calcium, which in addition to triggering osteopenia, increases risk of kidney stones and bone fractures. The heart doesn’t have to work as hard as it does on Earth, so it weakens over time, leading to deconditioning and even shrinkage. In animal models, weightlessness has been shown to slow development and interfere with genetic expression, including the triggering of genes associated with cell signaling, the immune system, and responses to stress.

A recent investigation by NASA found that long-term exposure to space affects females and males differently (credit: NASA)

The absence of gravity also wrecks eyeballs and the brain, while causing tremendous problems to a person’s sense of balance and bodily orientation (both in space and when returning back to Earth). In space, circadian rhythms are disrupted, and the body suffers loss of blood volume, immunodeficiency, and low red blood cell level count (post-flight anemia).


And then, there’s all that radiation to consider. Without sufficient shielding, prolonged exposure to radiation can facilitate cataracts, cancer, and many other health problems.

These are obviously serious problems, so unless we find ways to resolve them, the prospect of long term space occupation will remain out of reach.

Better Space Habitats?

One possible solution is to design more human-friendly space habitats, but this will inevitably prove to be easier said than done. In order to conform our space-based dwellings to the limitations of human form — a form expressly adapted for terrestrial life — we’ll have to overcome some serious technological challenges.



Take the prospect of artificial gravity, for example. It’s taken for granted that we’ll eventually build a centripetal space station that generates gravity through spin (like the one portrayed in 2001: A Space Odyssey). But as aerospace engineer John Page told ABC Science, this spin-based gravity may not work as elegantly as its often portrayed.

For instance, the habitable portion will have to be located at the tip or exterior of a very long axis, if the station is designed to rotate slowly. Otherwise, the station will have to spin at an extremely rapid rate to generate the required centripetal force — speeds that will make looking out of the window a very nauseating experience. What’s more, small- to medium-sized spinning space habitats will likely feature extremely narrow bands within which its occupants will be able to experience artificial gravity. It’ll be constraining, and likely very expensive. These stations will also be unscalable; it’s not immediately obvious how we could build fleets of interconnected spinning space habitats to accommodate thousands of occupants. Centripetal stations don’t lend themselves to modular designs.

Even if we do create the ideal space habitats, we’re still going to experience difficulties transitioning or adapting to alternative environments. Eventually, the occupants of space habitats or spacecraft will want to settle on a moon or planet. Once outside the cozy confines of the home habitat, colonists will once again be subject to conditions far removed from the artificial environments designed for Homo sapiens.

More realistically, if we’re going to entertain the prospect of sending humans into space for the long-term, we’re going to have to seriously consider human modification.

Humans Built for Space

The idea that humans will have to be redesigned for space is hardly new.

A very early depiction of a Clynes & Kline inspired cyborg. This painting by Fred Freeman appeared in the July 11, 1960 issue of LIFE Magazine.

The term “cyborg” was coined by Manfred Clynes and Nathan Kline back in 1960 with their groundbreaking publication, “Cyborgs and Space,” which they wrote for the benefit of NASA. The paper’s abstract sums it up nicely:



Altering man’s bodily functions to meet the requirements of extraterrestrial environments would be more logical than providing an earthly environment for him in space. Artifact-organism systems which would extend man’s unconscious, self-regulatory controls are one possibility.

NASA wasn’t really able to implement Clynes and Kline’s futuristic ideas, owing to the primitive state of cybernetics and biotechnology at the time. But that’s starting to change. Over the course of the next several decades and centuries, bioengineers will gain access to powerful new tools which they can use to make humans far more adaptable to space.

A depiction of a cyborg from the May 3, 1964 issue of the Miami News.

When it comes to transhuman-enabling technologies, there are four domains to consider: biotechnology (including genetics and regenerative medicine), nanotechnology (both materials and micro-robotic), information technology, and cognitive science. All four of these will play an important role in creating a version of humanity that can withstand the rigors of microgravity, radiation, and other problems posed by space.

Genetic Space Mods

Genetic engineering will prove to be a particularly effective tool.

(credit: Jer Throp/Flickr/cc)

For example, scientists have already isolated the LRP5/G171V mutation, which confers high-bone density, and the MSTN/IVS1+5G>A mutation which, through the suppression of myostatin, increases muscle mass and strength. Both of these interventions would prove beneficial for astronauts in space for the long-term and for those hoping eventually to return to Earth, or some other gravity well.


And it’s possible that many space-based wasting effects — or unpleasant effects such as inner ear changes that instigate motion sickness — could be offset, either partially or completely, through genetic interventions.

Scientists could use any number of techniques to exploit such mutations or to introduce trans-genes, including gene targeting by homologous recombination and CRISPR/cas9. With so-called “somatic” gene therapies, scientists will soon be able to target and swap-out the non-reproductive cells of adults.


Some of these changes, which could be passed down from generation to generation, would have to be conferred at the level of sperm and egg — which raises some ethical issues. And you wouldn’t want to make any changes of this sort without obtaining full, informed consent.

Synthetic biologist and geneticist Craig Venter has said that NASA has been doing “genetic selection” for quite some time now via astronaut selection. And the space agency will eventually have to make this practice more overt and rigorous.


“Not too many things excite my imagination as trying to design organisms — even people — for long term space flight, and perhaps colonization of other worlds,” noted Venter at a 2010 keynote lecture at the NASA Ames Research Center.

A Vacumorph, a deep space adapted human as envisaged by Dougal Dixon in Man After Man.

Indeed, it’s not just humans that will have to adapt to space, but the organisms within us. To that end, Venter has proposed that we develop a “synthetic microbiome.” For example, the microbe Deinococcus radiodurans can endure radiation doses 7,000 times higher than those that would kill a human. As noted by Mike Wall in Space.com, “If scientists can figure out how to incorporate such super-charged DNA repair genes into the human genome, astronauts won’t have to worry so much about the damaging cosmic rays hurtling through space.”

Solutions at the Nanoscale

Extremely small devices and special nanoscale materials hold promise as well, though many proposed solutions remain quite speculative. That said, it’s clear that nanotechnology has the potential to change humans, in ways that biology simply cannot.


For example, research has shown that nanotechnology works well to deliver drugs for treating bone diseases and to instigate bone regeneration. Relatedly, a Texas A&M University team has developed a material that heals broken bones. And early last year, scientists from the NanoTech Institute at the University of Texas at Dallas demonstrated powerful artificial muscles.

Special nanomaterials could also be used to shield the human skin from dangerous radiation — materials that could be either part of your body, or added on the surface.

Artificial muscles made from carbon nanotube yarns (credit: University of Texas at Dallas)

Eventually, microscopic machines called respirocytes could be used to deliver oxygen to the body’s tissues at rates hundreds of times greater than run-of-the-mill red blood cells. This would significantly decrease the burden placed on the heart and possibly eliminate the need for lungs altogether. Breathable air would become unnecessary, a benefit to astronauts working either outside or inside the space habitat.



Futurist Ray Kurzweil has speculated that nanotechnology could eventually eliminate our need to eat; tiny molecular machines could be used to manually deliver nutrients to our cells. For this to work, future astronauts would be equipped with a “nutrient belt” or other wearables loaded with billions of nanobots suffused with their cargo.

And as Trinity College professor James Hughes told Motherboard, nanotechnology could be used to offset the effects of radiation — but we’ll have to figure out ways to flush the damaged cells away from the body.

Cyborgs, Robots, and Consciousness Uploads

As per Clynes and Kline, space habitat dwellers could also have various parts of their bodies and physiological systems replaced outright by cybernetic technologies. A true bionic man or woman would be free from biological constraints and weaknesses. He or she would be capable of overcoming virtually every problem faced by human astronauts today.


Cyborg astronauts would have artificial limbs, organs, tissues — and even synthetic neurons and synapses, designed to withstand the rigors of space.

Through “soft” uploading, astronauts could use telepresence or virtual/augmented reality technologies to remotely operate a robot and maneuver it either inside or outside the spacecraft. In fact, the “astronaut” wouldn’t even need to leave Earth for this to work, though the lag time between communications would make the experience less than ideal.

The Cylons of Battlestar Galactica were able to upload their memories to other copies of their model through a central station.

For those willing to go the distance, however, “hard uploading”, in which the contents of a person’s brain is digitized and transferred to an alternative substrate, would allow astronauts to swap their bodies in a more literal fashion. One major benefit of this approach is that astronauts could upload their consciousnesses to different robots, depending on the nature of the task at hand. And when they’re done working, the astronauts could download themselves back to their default bodies — or supercomputer-based avatars. In fact, future space dwellers might not require a permanent body at all.



“[A] crew of human uploads implemented in solid-state electronic circuitry will not require air, water, food, medical care, or radiation shielding,” noted futurist Giulio Prisco in KurzweilAI.

A secondary benefit of uploading is that, in the event of a catastrophic accident, say a collision with space debris, a backup copy could be called upon to resume activities.

Granted, many of the ideas pitched here are futuristic and may never come to pass. Some of the proposed enhancements could lead to unforeseen problems, while others may never get past the inevitable ethical hurdles. But the more we learn about life in space, the more ludicrous the idea of sending an unmodified human out there seems.

Contact the author at george@io9.com and @dvorsky. Top illustration by Tara Jacoby.