Can humans survive the vast stretches of time that would be needed for space travel to faraway planets? A Greek scientist may have found the answer by looking at early humans who had the ability for prolonged hibernation.
NASA has long been looking for ways to send a crewed mission to Mars, but there are more than a few technical difficulties to overcome.
One of the main problems involving safe space travel for humans is the time needed to reach another planet. For instance, can man survive a 300,000-mile, seven-month trip to Mars and return safe and sound?
A Greek scientist may have discovered the answer, looking back into the deep past of mankind — namely, the evidence that early humans had the ability to hibernate for a prolonged period of time.
NASA is considering the idea of hibernation based on an article by Antonis Bartsiokas, of Democritus University of Thrace, and Juan-Luis Arsuaga, who co-wrote a scientific paper for L’Anthropologie.
Early humans had ability to hibernate for prolonged time
Their paper is based on findings from excavations in a cave called Sima de los Huesos – “the pit of bones” – at Atapuerca, in northern Spain.
Scientists found fossilised remains of dozens of humans at the bottom of a deep pit. The thousands of teeth and pieces of bones found there suggest that the place was a mass grave.
The remains are estimated date back more than 400,000 years and were most likely from early Neanderthals or their predecessors.
The site is one of the world’s most important palaeontological treasure troves, providing valuable information into human evolution in Europe.
However, one of the most interesting discoveries is an indication that the remains show seasonal variations that suggest that bone growth was disrupted for several months of each year.
According to the paper, pre-historic humans found themselves “in metabolic states that helped them to survive for long periods of time in frigid conditions with limited supplies of food and enough stores of body fat.”
The researchers say that many mammals — including primates such as bushbabies and lemurs — are known to hibernate.
“This suggests that the genetic basis and physiology for such a hypometabolism could be preserved in many mammalian species, including humans,” argue Arsuaga and Bartsiokas.
So if the human species does possess such a mechanism as part of its makeup, the question today is to find how this can be activated safely. That would certainly allow for bold space travel.
However, it is not certain if the environmental conditions in that area of today’s Spain more than 400,000 years ago resemble those of Earth today.
Therefore, we are still unsure whether safe, prolonged human hibernation is possible. Further research is needed looking at potential mechanisms needed for this to become a reality.
Recent technological and pharmacological advances have shown great potential to induce or manipulate sleep. But to induce prolonged human hibernation, extensive research on the brain is also needed.
Technical difficulties for space travel
Suppose science does find a way for astronauts to hibernate for space travel. There will still be some technical difficulties that humans must overcome before they reach the stars.
NASA and SpaceX, which work together on missions to the International Space Station, most solve some serious problems before such crewed missions take place.
The biggest challenge is the mass of the load needed to travel to space, meaning the spacecraft, people, fuel, supplies, etc.
Mass constrains the size of a Mars spacecraft and what it can do in space. Every maneuver costs fuel, and this fuel must currently be carried into space on the spacecraft.
SpaceX’s plan is for its crewed Starship vehicle to be refueled in space by a separately-launched fuel tanker. That means much more fuel can be carried into orbit than could be carried on a single launch.
Another challenge for travel to space is time, which is also connected with fuel.
Space travel to Mars more feasible
Crewless missions can travel complex trajectories around the Sun. They use what are called “gravity assist maneuvers” to effectively swoop around different planets to gain enough momentum to reach their target.
This saves a lot of fuel, but such missions can still take years to reach a destination in space. Can a crew survive years in space just to get to the destination — and then the same amount of years to return to Earth?
Both Earth and Mars have (almost) circular orbits and a maneuver known as the Hohmann transfer is the most fuel-efficient way to travel between two planets.
A Hohmann transfer between Earth and Mars takes around 259 days, (almost nine months) and is only possible approximately every two years due to the different orbits Earth and Mars take around the Sun.
A spacecraft could reach Mars in a little shorter time but it would cost more fuel to do it that way.
Even Return to Earth Not that Easy
The final challenge is the safe return of people to Earth after the jaunt in space.
The men from the Apollo 11 mission entered Earth’s atmosphere going about 40,000km/h (24,855 mph), which is just below the velocity required to escape Earth’s orbit.
Spacecraft returning from Mars will have re-entry velocities from 47,000km/h to 54,000km/h, depending on the orbit they use to arrive at Earth.
They could slow down into low orbit around Earth to around 28,800km/h (17,895 mph) before entering our atmosphere — but they would need extra fuel to achieve that.
These are just some of the challenges facing a journey to Mars and all of the technological solutions needed to make what sounds today like science fiction, the reality of tomorrow.
Sources: NASA, SpaceX, The Guardian, The Conversation, Scitech Daily