Interstellar Expansion WITHOUT Faster Than Light Travel

PBS Space Time
16 May 202421:14

Summary

TLDRThe video script discusses the concept of a generation ship, a theoretical spacecraft designed to support human life for multiple generations, enabling interstellar travel even without faster-than-light capabilities. It explores the challenges of such a mission, including propulsion systems, genetic diversity, life support, and the mental and social well-being of the crew. The script also touches on potential solutions like artificial gravity, efficient food and water production, and the use of virtual reality to combat isolation. The discussion highlights the importance of a stable social structure and the preservation of cultural knowledge across generations. Ultimately, it presents the idea that despite the risks and complexities, a generation ship could be within our reach, offering a new frontier for human exploration.

Takeaways

  • 🚀 The script discusses the concept of a generation ship, a spacecraft designed to support human life for multiple generations, as a potential solution for interstellar travel.
  • 🛸 The limitations of current propulsion technologies are highlighted, with the Parker Solar Probe's speed being insufficient for practical interstellar travel.
  • ⏳ The script explores two hypothetical scenarios for travel times: one with fusion propulsion reaching 3% the speed of light, and another with a much slower, 6,300-year journey.
  • 🧬 Genetic diversity is a critical factor for a successful generation ship, with a minimum crew size of 100 proposed to maintain a healthy population over centuries.
  • 🌌 The need for artificial gravity is emphasized to maintain the health of the crew during the long journey, with a rotating ring habitat suggested as a possible design.
  • 🌱 Food production is a significant challenge, with the requirement for a large surface area for agriculture, potentially supplemented by lab-grown meat or insects.
  • 💧 Water is another critical resource, with the need for efficient recycling and potentially large reserves for a multi-millennial journey.
  • 🌬 The importance of breathable air and the development of advanced recycling systems to convert carbon dioxide back into oxygen is discussed.
  • 🧘‍♂️ Mental health is a major concern for long-term space missions, with the script suggesting the use of virtual reality to combat isolation and maintain a connection to Earth.
  • 🤖 The potential role of AI in providing mental health support, such as an AI therapist, is mentioned as a tool to help maintain crew morale and cooperation.
  • 🔗 The script touches on the importance of preserving cultural knowledge and ensuring the mission's purpose is passed down through generations on the ship.

Q & A

  • What is the main topic of the episode mentioned in the transcript?

    -The main topic of the episode is the concept of a generation ship and the challenges of planning a mission to settle Proxima Centauri B using technology available within the next 30 years.

  • Why is the concept of a generation ship relevant to humanity's future in space exploration?

    -The concept of a generation ship is relevant because it presents a potential solution for long-duration space travel, allowing humans to reach distant stars within their lifetimes, despite the vast distances involved.

  • What propulsion technologies are mentioned as potential candidates for a generation ship?

    -The propulsion technologies mentioned include matter-antimatter engines, compact fusion drives, thermonuclear explosions, and the Parker Solar Probe's propulsion method using electrical power.

  • How does Einstein's special theory of relativity impact the feasibility of faster-than-light travel?

    -Einstein's special theory of relativity suggests that faster-than-light travel is almost certainly impossible, which is a significant limitation for interstellar travel within a human lifetime.

  • What are the potential speeds that a spacecraft could reach according to the script?

    -The script discusses spacecraft capable of reaching speeds of 80%, 90%, or even 99% the speed of light, as well as more realistic speeds of 3% and 10% the speed of light.

  • What is the closest known exoplanet to Earth, and why is it significant in the context of the script?

    -The closest known exoplanet to Earth is Proxima Centauri B, and it is significant because the script discusses a hypothetical mission to settle this exoplanet using a generation ship.

  • What are the challenges associated with ensuring genetic diversity on a generation ship?

    -Ensuring genetic diversity on a generation ship is crucial to maintain a healthy multigenerational crew and to populate a new planet. Challenges include avoiding genetic health issues over many generations and managing potential disasters that could reduce the population.

  • What is the minimum crew size suggested for a sustainable population on a generation ship?

    -The minimum crew size suggested for a sustainable population on a generation ship is at least 100 individuals, which would eventually multiply to a population of 500.

  • How does the script address the issue of providing food for the crew on a generation ship?

    -The script suggests using efficient hydroponic or aeroponic systems to grow nutrition-dense crops like sweet potatoes and considering alternative protein sources such as lab-grown meat or insects like mealworms.

  • What role does artificial gravity play in the health and well-being of the crew on a generation ship?

    -Artificial gravity, created by spinning the ship's habitats, is necessary to mimic Earth's surface gravity and prevent negative health effects associated with long-term exposure to zero gravity or microgravity, such as bone density loss.

  • How does the script propose to maintain the mental health and cultural continuity of the crew on a generation ship?

    -The script proposes using virtual reality to create immersive experiences of Earth environments, AI therapists to provide psychological support, and the development of a stable social structure that promotes crew happiness and mutual respect while maintaining the mission's objectives.

Outlines

00:00

🚀 The Quest for Interstellar Travel and Generation Ships

This paragraph introduces the concept of a generation ship as a potential solution for humanity's desire to explore the universe, despite the limitations imposed by the vast distances and current propulsion technologies. It discusses the possibility of traveling at a fraction of the speed of light and the implications of relativistic time dilation. The paragraph also presents the hypothetical scenario where NASA tasks PBS Space Time with planning a mission to settle Proxima Centauri B, the closest known exoplanet to Earth, within a tight timeframe of 30 years, necessitating a multi-generational space journey.

05:02

🛰️ Propulsion Methods and the Challenges of Long-Term Space Travel

The second paragraph delves into the technical aspects of propulsion systems needed for such a long journey, comparing the Parker Solar Probe's technology with the more speculative but potentially faster nuclear fusion propulsion. It outlines the challenges of achieving the necessary speeds to reach Proxima-B in a reasonable timeframe and discusses the implications of traveling at different speeds on the size of the ship and the number of generations involved. The paragraph also references studies by French scientists Frédéric Marin and Camille Beluffi on the minimum number of humans required for genetic diversity and a sustainable population during the journey.

10:03

🌱 Sustaining Life: Food, Water, and Air for Generation Ships

This paragraph addresses the critical needs for sustaining life on a generation ship, focusing on food production, water recycling, and breathable air. It discusses the space requirements for growing crops and raising livestock, the challenges of providing a balanced diet, and the necessity of efficient water and air recycling systems. The paragraph also explores the idea of using insects as a protein source and the potential for leveraging water as radiation shielding, highlighting the importance of creating a self-sustaining biosphere for the long-term health and survival of the crew.

15:04

🧘‍♂️ Mental Health and Social Dynamics in Space Travel

The fourth paragraph examines the mental health and social challenges that crew members would face on a generation ship, particularly the sense of isolation and the need for maintaining a connection to Earth. It suggests the use of virtual reality to provide comforting Earth-like environments and to maintain communication with loved ones as the time lag increases. The paragraph also introduces the concept of an AI therapist to assist with psychological support and the importance of establishing a culture and social structure that balances operational efficiency with crew happiness and individual freedoms.

20:08

🎥 'Space: The Longest Goodbye' Documentary and the Human Aspect of Space Travel

The final paragraph shifts focus to the documentary 'Space: The Longest Goodbye,' which explores the psychological challenges astronauts would face during long-term space missions, such as a three-year mission to Mars. The documentary aims to bridge the gap between the aspirations of space travelers and the psychologists tasked with ensuring their mental stability. It is promoted as a compelling exploration of the balance between the dreams of space exploration and the harsh realities of living in space, available for viewing on YouTube and later exclusively on the PBS app.

Mindmap

Keywords

💡Generation Ship

A generation ship is a theoretical type of interstellar spacecraft designed to support human life for multiple generations on a journey to another star system. In the context of the video, it is a central concept as it discusses the possibility of using such a ship to travel to Proxima Centauri B, ensuring the survival and continuation of the human species over potentially thousands of years.

💡Relativistic Time Dilation

Relativistic time dilation is a concept from Einstein's theory of relativity, which states that time passes slower for objects moving at speeds close to the speed of light relative to a stationary observer. The video mentions this phenomenon to explain how a spacecraft traveling at a significant fraction of light speed could reach distant stars within a human lifetime due to time slowing down for the travelers.

💡Matter-Antimatter Engines

Matter-antimatter engines are a theoretical form of propulsion that would use the mutual annihilation of matter and antimatter to produce energy. The script discusses these engines as a potential propulsion method for a generation ship, capable of achieving high speeds that would allow for relativistic time dilation effects to come into play.

💡Compact Fusion Drives

Compact fusion drives refer to a hypothetical propulsion system that would use nuclear fusion reactions to generate energy for space travel. The video script explores the possibility of using such drives for a generation ship, although it acknowledges that this technology is not yet commercially viable.

💡Proxima Centauri B

Proxima Centauri B is the closest known exoplanet to Earth, located about 4.2 light years away in the Alpha Centauri system. The video script uses this exoplanet as the destination for a hypothetical generation ship mission, emphasizing the urgency and importance of such a journey in the face of existential threats to Earth.

💡Genetic Diversity

Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. In the context of the video, it is crucial for the health and sustainability of a multigenerational crew on a generation ship, as a lack of diversity could lead to genetic health issues over long periods.

💡Artificial Gravity

Artificial gravity is the simulated gravitational force that can be created by centripetal force, such as by spinning a spacecraft. The script discusses the necessity of artificial gravity for the health of the crew on a generation ship, to prevent the negative health effects associated with long-term exposure to zero gravity or microgravity.

💡Water Recycling

Water recycling refers to the process of purifying and reusing water that has already been used. The video emphasizes the importance of highly efficient water recycling systems for a generation ship, given the need to sustain a large population over potentially thousands of years without access to new water sources.

💡Cryogenics

Cryogenics is the study of the production and effects of very low temperatures, often associated with the preservation of biological matter. The script briefly mentions cryogenics as a potential method for preserving the crew during space travel, but suggests that it may not be reliable enough for a multigenerational journey.

💡AI Therapist

An AI therapist is an artificial intelligence designed to provide psychological support and therapy. The video script suggests the use of an AI therapist to help maintain the mental health of the crew on a generation ship, especially considering the isolation and potential for interpersonal conflicts in such a confined environment.

💡Cultural Preservation

Cultural preservation refers to the act of maintaining and passing on cultural knowledge, traditions, and practices. The script touches on the importance of preserving the cultural identity and knowledge of the Earth for the generations born and raised on a generation ship, to ensure that they remain connected to their origins.

Highlights

Introduction of the documentary 'Space: The Longest Goodbye' available on the PBS App and YouTube.

Discussion of the limitations of our generation's ability to explore space due to the vastness of the universe.

Proposal of a generation ship as a potential solution for interstellar travel.

Explanation of why faster-than-light travel is considered impossible based on Einstein's theory of relativity.

The concept of relativistic time dilation and its implications for interstellar travel at speeds close to light.

Challenges of developing propulsion methods like matter-antimatter engines for high-speed space travel.

Hypothetical scenario of an existential threat prompting a mission to settle Proxima Centauri B.

Constraints of technology and time in planning a realistic interstellar mission within 30 years.

The necessity for a generation ship to support multiple generations of humans on a long-duration space journey.

Consideration of propulsion systems like Parker Solar Probe and nuclear fusion for the generation ship.

Estimation of travel times to Proxima-B based on different propulsion speeds.

Importance of genetic diversity and the minimum crew size for a sustainable population on a generation ship.

Calculations by Marin and Beluffi on the number of humans needed for a healthy multigenerational crew.

Challenges of providing sufficient living space, artificial gravity, and life support for the crew.

Innovative ideas for food production, such as hydroponics, aeroponics, and insect farming on the ship.

The critical need for water recycling and the potential use of water as radiation shielding.

Discussion on air recycling and the use of plants for CO2 conversion in a closed-loop system.

Addressing mental health challenges of isolation through the use of virtual reality and AI therapy.

Ensuring the continuity of mission objectives and cultural preservation across generations.

Speculation on the social structure and culture needed for a stable and happy ship-bound society.

Conclusion on the possibility and challenges of building a generation ship to reach Proxima B.

Recommendation to watch the feature-length documentary 'Space: The Longest Goodbye' for further insights.

Transcripts

00:00

Before we get started I wanted to let you know,  

00:02

today’s episode is brought to  you by

00:04

Space:  The Longest Goodbye. Available now on the PBS App and YouTube. So check out the link below.

00:11

We are the middle children of history. Born  too late to explore Earth, and born too early  

00:16

to explore the universe —- to partially quote  someone on the internet whose wisdom is only  

00:21

matched by their anonymity. In the far future  we may have advanced propulsion technologies  

00:27

like matter-antimatter engines and compact  fusion drives that allow humans to travel  

00:32

to other stars on timescales shorter than their  own lives. But what if those technologies never  

00:38

materialize? Are we imprisoned by the vastness  of space—doomed to remain in the solar system  

00:44

of our origin? Perhaps not. A possible path to a  contemporary cosmic dream may just be to build a  

00:53

ship which can support human life for several  generations; a so-called generation ship.

01:05

Faster than light travel is almost certainly  impossible—so says Einstein’s special theory  

01:11

of relativity—and we rarely win when we bet  against Einstein. That sounds like bad news  

01:17

for the galactic future of humanity given that  the Milky Way is 100,000 lightyears across,  

01:22

and there are relatively few stars within what  most would consider to be a reasonable commute.  

01:29

But that doesn’t mean we can’t reach for the  stars. If we can build spacecraft capable of  

01:34

reaching 80, 90, even 99% the speed of light  then relativistic time dilation would slow the  

01:41

clock of the spacecraft relative to Earth’s.  At these speeds a single crew could reach an  

01:46

interstellar destination up to 100s of light  years away within their own lifetimes. But  

01:52

such speeds would require some pretty out-there  propulsion methods like matter-antimatter engines,  

01:58

compact fusion reactors, or even black  hole drives. And even if we eventually  

02:04

do build such devices, there are a whole  range of dangers that uniquely arise when  

02:10

traveling through the cosmos at such high  speeds, as we’ve discussed previously.

02:15

So, what if it turns out we have to travel the  slow road? What if it proves impossible to send  

02:22

humans any faster than a tiny fraction of the  speed of light? Or what if we decide we  

02:29

really really need to leave Earth ASAP using  technology that we at least understand today.

02:35

OK, Here’s the scenario: Something is coming. It  could be a comet impact or catastrophic climate  

02:42

collapse or the Tri-Solarian fleet. Whatever  it is, there’s enough of an existential threat  

02:48

that we decide to insure the future of our  species by trying to settle another world.  

02:54

Quite naturally, NASA tasks PBS Space  Time with planning a mission to settle  

03:00

Proxima Centauri B in the Alpha-Centauri system.  This is the closest known exoplanet to Earth at a  

03:05

mere 4.2 light years away. To keep things simple,  let’s pretend that we discovered that Proxima-B  

03:11

is already habitable so all we need to do  is get some people there in good condition.

03:17

We only have a few decades to make this happen, so  ultra-advanced propulsion is out of the question.  

03:24

We launch whatever we can throw together in around  30 years. The fastest ship we could conceivably  

03:31

hope to build might reach speeds of 10% that of  light. That’s a 42 year journey—launch a crew in  

03:38

their 20s and they’ll arrive at retirement age.  More likely our craft will travel much slower,  

03:46

so that no crew that starts the journey will live  to see its end. Assuming that cryogenics won’t  

03:53

be 100% reliable within decades—which is pretty  fair—it sounds like we need to plan for a mission  

03:59

in which multiple generations of humans are  born, live, and die en route, and that landfall  

04:06

is made by descendents of the launch crew. It  sounds like we need to plan a generation ship.

04:12

There are lots of decisions to make in how  we do this, but remember our constraint:  

04:18

it has to be something we can plausibly  launch in 30 years. We’re going to need  

04:22

to choose a propulsion system, a crew size  and composition, life support systems, and  

04:27

finally we need to ensure the mental, social and  cultural wellbeing and stability of this group.

04:33

Starting with the propulsion method; this  determines the speed we can travel, the potential  

04:38

size of the ship, and so the size and number of  generations of the population we need to sustain.

04:43

The fastest vehicle ever built by humans is  the Parker Solar Probe, which accelerates by  

04:49

blasting a propellant—hydrazine in this  case—using electrical power. Although it  

04:54

was really more the gravitational assists that  enabled the Parker to reach 700,000 kilometers  

05:01

per hour. If we could scale up this tech to  something large enough to carry lots of humans then  

05:08

at this speed we could get our crew to Proxima-B  in … 6,300 years. That’s like 200 generations,  

05:18

and roughly the length of recorded human  history. It’s difficult to imagine that  

05:23

nothing would go wrong in that much time. But we’re  also pretty sure we can get a ship to this speed,  

05:30

so we should see if this timescale  is at least feasible. Also, this is the speed  

05:36

assumption made by French scientists Frédéric  Marin and Camille Beluffi in a series of  

05:42

studies, and we’ll be coming back to their  conclusions regarding a trip of this length.

05:46

We’ll also consider a much faster  craft—one propelled by nuclear  

05:50

fusion—smashing light elements together to  form heavier elements plus lots of energy,  

05:55

just like the Sun does. We haven’t yet managed  to build a commercially viable fusion reactor,  

06:00

let alone the sort of compact reactor we’d  need for a spacecraft. But there IS a fusion  

06:06

technology that we’ve thoroughly mastered—and  that’s the thermonuclear explosion. There are  

06:11

various concepts for spacecraft that  accelerate under a series of fusion  

06:16

pulses—aka explosions—rather than sustained  fusion reactions. These vary in sophistication  

06:23

from the more advanced internal confinement  engine of Project Daedalus to more achievable,  

06:30

if scarier proposals where you literally detonate  thermonuclear explosions behind the craft,  

06:35

like in Project Orion or the Enzmann starship,  or into a forward sail like in the Medusa design.

06:43

Top speeds for some of these have been estimated  at 30% lightspeed, but that’s highly optimistic.  

06:50

A little under 10% is more realistic for a  mature version of this technology. For us,  

06:55

with our limited timeline, we’re going to assume  we can get to 3% lightspeed. That’s around 50  

07:02

times faster than our conventional drive, so  gets us to Proxima-B in a mere 140 years—just  

07:08

four or five generations. So, today we’re going  to plan towards these two travel times—140 years  

07:14

if fusion pans out and 6300 years if not. We’ll  have teams working on both, and you can think of  

07:22

these as representing the extreme boundaries of  what we can achieve in the little time we have.

07:27

The next decision will influence all of the  choices that follow. How many people are we  

07:33

sending? This determines the size of the ship  or ships and the resources we need to bring.  

07:38

Perhaps the most important factor determining  population size on a generation ship is the  

07:43

issue of genetic diversity. There are two aspects  to this: how many people are needed to ensure a  

07:49

healthy multigenerational crew during the journey,  and how many are needed to healthily populate a new planet.

07:57

A 6300 year journey means 200 generations  give or take. If the genetic diversity of  

08:04

the starting population isn’t sufficient there  will be genetic health issues en route. Marin and  

08:09

Beluffi explore this question in a 2018 paper.  They use Monte Carlo simulations to calculate  

08:15

the minimum number of humans that would be needed  to avoid many of the potential genetic pitfalls,  

08:20

also accounting for various forms  of misfortune such as a random  

08:24

disaster eliminating a third of the population,  different infertility rates, and even an overall  

08:29

“chaotic factor” intrinsic to any human  exploration. From all of this they came  

08:34

up with the minimum numbers needed to  achieve a sustainable population during  

08:38

the journey. They conclude that we need to  launch with a crew of at least 100, who will  

08:44

multiply to a population of 500—and that’s  the level to support for most of the journey.

08:49

How big a ship does it take to  comfortably carry 500? Well,  

08:54

SpaceX’s Starship is supposed  to be able to carry 100. So,  

08:59

the equivalent of 5 of those at least? However  that doesn’t include the space needed for  

09:05

systems to support 500 lives long term. For that  we’re definitely going to need a bigger boat.

09:13

Missions around the solar system don’t  need to be luxurious. But centuries or  

09:19

millenia long trips to Proxima-B will  need some home comforts. Like gravity.

09:25

Living in zero gravity or microgravity  has clear negative effects on health,  

09:31

with the most well documented being on bone  density. To avoid our travelers reaching  

09:35

Proxima-B as Wall-E-esque gelatinous  blobs, we need artificial gravity.

09:41

We’ve discussed previously how this could be  done. There’s only one way, and fortunately  

09:47

it’s not that complicated. The ship’s  habitats need to be spun in a circle to  

09:52

give 1-g of centrifugal acceleration,  perfectly mimicking Earth’s surface  

09:58

gravity. There are lots of designs  for centrifugal artificial gravity,  

10:02

but the simplest might be a rotating ring habitat.  A 100m radius ring would need to rotate 3 times  

10:10

per minute to replicate Earth gravity. That  seems not completely crazy, so let’s move on.

10:17

The next step is to feed our crew Another study  led by the French team finds that we’d need 0.45  

10:25

km^2 for an omnivorous and balanced diet. Our  5 Starships have a surface area of about 1%  

10:34

of that. So we either send 500 starships  just to feed our crew, or find a way to  

10:41

produce food more efficiently. That 0.45 km^2  is dominated by the space for raising livestock,  

10:49

so burger night is the first thing we’ll have  to cut. It’s possible to get the required area  

10:55

down 0.015 km^2 if we grow nutrition-dense crops  like sweet potatoes using our best hydroponic or  

11:04

aeroponic systems. That’s just 30 starships worth  of farm, so we’re back in the realm of the sane.

11:11

The crew is also going to need protein.  Now maybe we can get the quantity and variety  

11:17

from an efficient veggie source, especially  with a little genetic tinkering. But if not  

11:23

there are plausible meat options. Now lab-grown meat  technology is a bit speculative at the moment,  

11:30

but there’s a very well established carnivorous  option suited to the less squeamish interstellar  

11:35

traveler. I’m talking about insects. For example,  mealworms can be farmed at high densities and  

11:42

provide extreme protein richness. One to a few  Starships worth of mealworm might do the trick.

11:49

Overall, we’re going to need something  like 6 to 10 times our crew’s living  

11:53

space for food production. And that’s for  a pretty boring and slightly crawly diet.  

12:00

But maybe there are some gourmet yam and  grub recipes just waiting to be discovered.

12:05

A bigger challenge than food is the water, which  our travelers need in order to grow that food,  

12:11

and also in order to just live. An adult  human needs around 2 liters of water per day,  

12:16

give or take. 500 humans need 1000 liters  per day—that’s a cubic meter weighing a  

12:22

metric ton. Our 140 year journey may  be able to haul the required 50,000 tons of water —just  

12:29

barely—but forget about it for our 6300 year  slog. In either case we’re going to want very  

12:36

good water recycling. Just recently, the ISS  reached a new milestone of 98% water recycling  

12:43

efficiency. Now if that’s as good as we get for our  “fast” mission we need a more reasonable 500 ton  

12:52

supply of reserve water—perhaps one Starship  worth of water storage in terms of volume.

12:58

For our 6-millenia-slog we need 50 times that. So  our generation ship just doubled in size just to  

13:07

haul enough water. And remember that we haven’t  even considered water used and lost growing food.  

13:14

Maybe add as much water again for 100 starships in  water. In order for the long trip to be plausible,  

13:20

we may need to focus on improving our water  recycling—get it to at least 99.5% efficiency,  

13:27

which brings the reserve storage requirement  down a factor of four to a similar scale as our farm requirement.

13:35

There is perhaps one upside to  needing to store all this water,  

13:39

and that’s that water can double as radiation  shielding. About one meter depth of water  

13:44

surrounding habitats is enough to stop  most dangerous space radiation. This is  

13:49

a solution that’s being considered for  trips to Mars, but would work well for  

13:54

a non-relativistic interstellar trip. By the  way, this is an upside of traveling relatively  

14:00

slowly—relatively minimal shielding is sufficient  and bumping into a single dust grain doesn’t kill us.

14:08

The last ingredient to add to our ship's biosphere  is breathable air. Just as with water, recycling  

14:14

is critical here. The ISS currently uses a system  designed by the European Space Agency called the  

14:19

Advanced Closed Loop System, which recycles  carbon dioxide back into breathable oxygen,  

14:24

with around 50% efficiency. That’s  not nearly enough for a generation  

14:29

ship because huge supplies of fresh oxygen would  be needed to replenish the losses. Instead,  

14:35

we’d probably need to rely heavily on our natural  CO2 recyclers—the plants we are growing for  

14:42

food. There have been various efforts to build  self-contained biospheres capable of sustaining  

14:47

a breathable atmosphere. Maybe the most famous is  the Biosphere 2 project, which did OK, all things  

14:53

considered. Yes they had to install artificial  CO2 scrubbers to help the plants, but the  

14:59

project at least demonstrated that a combination  of natural and artificial systems could maintain  

15:03

a breathable atmosphere for some time. We have  a few decades to perfect this, so there’s a good  

15:09

chance we can come up with an air recycling  system that will work over long timescales.

15:14

So maybe we can keep our crew alive  and physically healthy for centuries,  

15:18

or even millenia. But will they be  happy? And will they stay sane? The  

15:25

sense of isolation on such a long voyage  will likely be a major challenge for  

15:29

maintaining the mental health of the crew.  We need them to feel connected to Earth,  

15:35

to be part of something grander than their  janky little spacecraft on its lonely journey.

15:40

The first generation in particular will want  to stay connected to their loved ones. But  

15:44

the two-way light travel time between the ship  and the Earth will increase over the journey,  

15:49

ultimately reaching a lag of  nearly 8.5 years near the end

15:52

NASA has done some tests to mitigate  the dread that could follow from such separation  

15:59

from our home world. One solution could be the  use of virtual reality. Crew members could find  

16:04

solace in digital 3D models of comforting and  beautiful Earth environments, and in the case  

16:10

of generation one, their homes and loved ones.  As the time lag increased, messages from friends  

16:17

and family and well-wishers could be recorded on  Earth, beamed to the ship, and played back in VR.

16:22

On our cramped and sterile spaceship, it  may be important to grant our travelers  

16:27

certain experiences that we on Earth take  for granted. By improving the immersion and  

16:32

interactivity of our VR technology we may be  able to provide convincing visual experiences  

16:38

of mountains and sunsets, and auditory and  even tactile experiences of wind and rain,  

16:44

and the olfactory joys of a forest or freshly  cut grass. We can’t build a StarTrek holodeck,  

16:51

but we can certainly push VR a lot  further in the time we have before launch.

16:56

Of course, the humans on the ship will  still be humans. Arguments will happen,  

17:00

relationships will experience strain, and  sensitivity and frustration levels may be  

17:04

heightened due to the isolation and confined  spaces. And yet a high level of synergy and  

17:10

teamwork is needed for this mission to succeed.  Sometimes a stressed human needs another human.

17:15

But maybe, when tensions rise and trust wanes,  it would be helpful to have a trusted third  

17:20

party to give advice, confide in, and to overall  receive encouragement from. One that remembers  

17:29

and learns from the problems of  past generations. Maybe we need  

17:33

an AI therapist. NASA has already piloted such  a tool, namely Cimon 2.0 the therapy AI robot.  

17:42

Preliminary testing seems promising and it  is generally agreed upon that some tool or  

17:48

AI of this form will be incredibly important  for the success of a long term space mission.

17:54

Our plan so far will hopefully get our crew  to Proxima-B in good health, genetically,  

17:59

physically, and mentally. But how do we  make sure that the mission of the launch  

18:03

crew is still the mission of the landing  crew? How do we ensure that the knowledge  

18:07

and skills needed to complete the mission  are passed across generations? Or that we  

18:13

preserve the wealth of cultural knowledge  and tradition of these once-Earthlings?

18:18

This is where things get more speculative as there  isn’t much research to go on. We just know that  

18:24

this stuff is going to be very important  and probably very tricky. The ship-bound  

18:29

society is going to need a culture and social  structure that balances different needs.  

18:34

That structure needs to enable efficient  operation of the mission—which may mean  

18:39

clear hierarchies in each operational area.  But the culture also needs to promote crew  

18:44

happiness—otherwise we have a revolution  in a generation or two. So, an efficient  

18:50

and stable social structure that somehow also  promotes mutual respect, individual freedoms,  

18:55

and all the various values that we want this  new branch of humanity to carry forward.

18:59

Overall, it seems at least possible to build  a generation ship that can reach Proxima B,  

19:05

to launch in the not-to-distant future. There are  so many things that we know could go wrong—and  

19:10

no doubt many more unknown fail points. And the  longer the mission, the more risk of unexpected  

19:17

disaster, so maybe we should really focus on  getting fusion on track. But it’s encouraging  

19:22

to think that this sort of sci-fi endeavor  is at least within our grasp if existential  

19:28

need or our adventurous spirit compels  us. We are the middle children of history,  

19:34

but perhaps we’re ready to grow up. Perhaps  soon our generation ships will slip the bonds  

19:40

of gravity and distance to explore the  new frontier of interstellar spacetime.

19:46

Hey Everyone. If you enjoyed today’s episode  then I highly recommend you check out the new  

19:50

feature length documentary “Space: The Longest  Goodbye.” The film explores the realities that  

19:56

NASA’s goal to send astronauts to Mars would  require a three-year absence from Earth,  

20:02

which would be twice as long as the current record  for consecutive time in space. Bridging the gap  

20:07

between the astronauts who dream of space  travel and the psychologists whose job is  

20:12

to keep astronauts mentally stable in outer  space, the documentary vividly displays how  

20:17

those who dream of space travel must balance  their dream of reaching new frontiers and the  

20:23

harsh psychological realities of space.  The film is now available on YouTube so  

20:28

check out the link below. After June 4th, it  will be available exclusively on the PBS app.

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العلامات ذات الصلة
Interstellar TravelGeneration ShipSpace ExplorationHuman SurvivalPropulsion SystemsRelativistic EffectsCultural PreservationMental HealthSpace TechnologyFuture Frontiers
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