# How many crews are needed to survive on the road to the Proxima Centauri star system?

## The Heritage algorithm of two French scientists will give us the answer.

If humans want to become intergalactic creatures, it is obvious that we will have to travel long distances by light years to a planet that can support life in a distant galaxy. Last year, the neighboring galaxy Proxima Centauri became a bright candidate - on which several exoplanets (exoplanets - exoplanets) have the potential to become the second Earth.

Proxima Centauri is 4.2 light-years from Earth, a distance of 6,300 years with current technologies we have. Such a long journey will take generations, and those on the historic journey will not be able to see the new roof firsthand (unless we have successfully developed cryogenic technology). Their will be the first generation to set foot on the distant planet.

Proxima Centauri through the "eye" of the Hubble telescope.

To prepare for this trip, we consider the spacecraft, the technology to synthesize the fuel on the move, the essential food, but sometimes we forget the simplest question: how much does the crew need Are you the only one who can guarantee a noble mission with a high chance of success? What is the minimum number of people required to stay aboard to ensure that the descendants of Generation # 1 are genetically healthy?

Today, we can answer this question thanks to the work of Frédéric Marin, a researcher working at the University of Strasbourg and Camille Beluffi, working for the research firm Casc4de; Both of them are French nationals. They calculated the crew survival rate with the number of different members, along with specific reproduction rules for the mission to succeed.

First , we need a little context. Scientists and engineers have studied the different ways that humans can be brought to the nearest star system. The two most obvious factors are the distance in light years between the two star systems and the current speed of the spacecraft.

The Apollo 11, which took man to the moon, flies at 40,000 km / h; At this incredible speed, we will reach Proxima Centauri in . over 100,000 years. Fortunately, the spacecraft was much faster than before. For example, the solar probe - the Parker Solar Probe, scheduled to be launched this year, will fly at a speed of more than 700,000 km / h, about 0.067% the speed of light.

Parker Solar Probe, NASA's Sun probe.

Marin and Beluffi use the above figures to calculate.'At this rate, an interstellar journey to the planet Proxima Centauri b will still take 6,300 years , ' they said. If the average human age is 70 years, 6,300 years would be equivalent to 90 generations .

It is not easy to choose the # 1 crew on the historic journey. Important factors include the number of men and women in the group, the age and life expectancy of the cough, the success rate of having children, the capacity of the ship and more. Other factors include the age at which a child is born, how close a couple is planning to have children, how many children they can have, etc.

Once these factors were calculated, the team used an algorithm called Heritage to simulate an interstellar travel mission for generations of people. First, the algorithm will create a crew with the quality specified in the input data, and then will conduct a theoretical test. This process involved both natural death and accidental death each year, to see how many crews it would take to continue the next generation.

It is not easy to choose the # 1 crew on the historic journey.

Among the crew members, the algorithm chooses two random people of two different genders and calculates their fertility rate, based on each person's fertility and the relationship-related limits. inbreeding. If the pregnancy rate is high, the algorithm will create a new crew member and repeat this loop until the crew dies or the Proxima Centauri star system after 6,300 years.

Every time you run this historic mission, the algorithm adds a catastrophic event - a mysterious epidemic, a collision with a celestial body or any accident - to reduce the number. Member of the crew go ⅓.

The algorithm will run each mission 100 times to find the percentage of crew with a certain number of people survived for 6,300 years.

Another key is to what extent inbreeding reproduction will be performed . After calculating many different situations, Marin and Beluffi decided that no couple would have inbreeding, to have a child, a couple had to not be related by blood. They ran a total of 100 missions with different crew numbers, to find the highest success rate.

Very interesting results. The Heritage algorithm predicts that with a 14-member crew , the mission will fail miserably, the crew will perish before reaching Proxima Centauri. Such a small group would not have enough genetic diversity to survive.

With a crew of 14 meeting, the mission will fail miserably.

Through animal studies, the researchers found that with 25 couples and a careful breeding plan, this group of creatures will survive forever. However, the Heritage algorithm is tougher than that, as well as the harshness between the natural conditions on Earth and the deadly coldness of the Universe: with 25 men and 25 women, up to 50% of the crew will be deleted. the book before it reaches Proxima Centauri; The main reason is due to the unfavorable random event taking place over a period of 6,300 years.

According to Heritage algorithm, the success rate does not reach the 100% mark until the crew has a total of 98 people, that is, 49 couples . ' At that time, we can confirm that under the factors included in the experiment, a crew of 98 will be the minimum condition to complete the 6,300-year journey to Proxima Centauri b '.

This can be considered as a mock up to serve as a foundation for more detailed later tests. First, the rate of having a successful child will be different in the Cosmic environment, the rate for a healthy child will be lower due to the effects of Cosmic radiation. The rate of disaster occurrence will be lower than the possible social conflicts when hundreds of people live together in a spaceship. A more advanced Heritage algorithm will probably overcome these factors, re-running a series of new experiments to get more accurate numbers.