One subject that caught my eye several months ago seems like a natural follow up to the posting I wrote on September 17th about what the Monarch Butterfly could teach us about biological ways to succeed at interstellar travel. For humanity to send a reproducible population to a second Earth in a neighbouring solar system presents an enormous challenge for which we currently lack the knowledge and technology. Our imperfect understanding of population genetics and the dangers of interstellar space makes it highly improbable that we can pull this off without massive loss of life, and in the end without knowing if the people we send actually make it to their destination.

An astrophysicist at the University of Strasbourg, Frédéric Marin, has recently published a paper in which he works the success numbers for an interstellar crew complement taking a 6,300-year journey to Proxima Centauri-b, the planet  referenced in my previous Monarch Butterfly posting.

Why 6,300 years? Marin chooses an optimal speed for the spacecraft of better than 500,000 kilometers per hour, three times faster than the Juno spacecraft currently circling Jupiter. At that speed the 40-trillion-kilometer voyage would last more than 6 millennia.

Marin looks at parameters for survival including issues like sudden death, accidents, space rock collisions, cosmic rays, infertility, inbreeding, pandemics and unforeseen random events. Applying a Monte Carlo simulation, a program called Heritage, Marin recently ran several different population configurations to determine the optimal minimal number needed to survive a multi-generational voyage. If you are unfamiliar with Monte Carlo simulations, these were first conceived by scientists who were working on the Manhattan Project to help them use quantitative analysis to predict a range of possible and probable outcomes.

Marin, who normally simulates remote galaxies and black holes, used Heritage beginning with 50 humans made up of 25 breeding-aged pairs. At those numbers Heritage concluded a crew would not survive the voyage. He then raised the numbers incrementally testing each in the simulation. All scenarios up until the number 98 indicated failure with the human crew dying off before reaching Centauri-b. But at 98, Heritage predicted a 100% survival outcome.

With 98 healthy humans, the population would be self-perpetuating with enough diversity to make up for the lack of being able to remove old genes through emigration and introduce new ones by immigration. Marin’s spaceship simulation allows for the 98 to grow the population over the journey to 500 as the interstellar spaceship gets close to Centauri-b.

Even Elon Musk’s BFR, the largest passenger rocket ship being planned today wouldn’t be able to handle a crew of 98, 30 at best, according to those who have studied the specifications. So one can conclude that the infrastructure and self-sustaining, environmental requirements of an interstellar ship are well beyond our best technological skill sets today.

But the exercise regardless has merit Marin states: “The same elements are essential for any self-sustaining colony, so our code can easily compute the survival rate of a group of humans after a local or global catastrophe as well.” I guess one could call this good post-apocalyptic thinking.

But others tackling the same thought experiment have disputed the number. One of those is anthropologist Cameron Smith, of Portland State University in Oregon, who has come up with a minimum of 14,000 to a maximum of 44,000 as the right numbers for human survival through interstellar space.

In his study, Smith concludes that the unforeseen has to be accounted for such as sudden death by accident or disease involving a disproportionate number of either the female or the male population which would impact viable genetic diversity to ensure survival.

As an anthropologist, Smith uses Polynesian migration modeling which looks at the numbers needed for a small population to spread from one island to many throughout the Pacific Ocean. Smith states that Polynesian groups of up to 100 or fewer hunter-gatherers set out on long sea voyages to reach other islands. The Polynesians came in a series of waves. Many didn’t survive these journeys. Many died after arrival. But the total number of migrants amount to the tens of thousands. Otherwise colonization fails. The same can be said about the European colonization of the Americas, New Zealand, and Australia. Thousands died before sustainable populations were established.

Of course, neither Marin or Smith in their thought experiments considered altering the human genome of the crew to make the voyage survivable. In my Monarch Butterfly article, I theorized that advanced genetic engineering would allow us to alter the species and make us genetically flexible. We could even go through a metamorphosis turning into chrysalides to emerge before making landfall at a new planet. On a trip to Centauri-b we would thus minimize many of the risks that both Marin and Smith accept as necessary to human migration over the long distances and perils of interstellar space.

The story of the Monarch came back to me this week when I read about students and researchers at Delft University of Technology, in The Netherlands, working on the design of a starship, an interstellar spacecraft designed to ferry humans from our Solar System to some distant one in the Milky Way. With the help of the European Space Agency (ESA), DSTART, the Delft Starship Team, came up with a cocoon-like design using a hollowed-out asteroid as the equivalent of our Monarch chrysalis to protect a multi-generational human crew crossing interstellar space to emerge on the surface of an alien planet circling a neighbouring benevolent star.

Identifying a Nearby Second Earth

It may seem far-fetched but before the end of this century, humanity could take what seems to be an impossible leap, an outward bound journey to Proxima Centauri where one of its planets could become home to our species. The planet in question is Proxima b. It is a Super Earth, 1.3 times the size of our planet. And although its orbit is 1/20th that of the Earth-to-Sun distance, because it circles a weaker red dwarf star, the amount of solar energy falling on its surface is roughly 2/3s that of Earth which still qualifies it to be in what exoplanet searchers call the Goldilocks Zone, where water exists on the surface and atmosphere in all three states. It is a given that we will need to know a lot more about Proxima b before ever considering sending a spaceship to it with a human crew aboard. Future space and ground-based telescopes should tell us if Proxima b is protected like Earth with its own magnetic field. That would certainly make it even more attractive exoplanet destination.

Going Interstellar Requirements

Before making the decision to go interstellar we have a lot of technology and science to address including:

1. Completing our understanding of how our species could adapt physiologically and psychologically to what could be decade-to-century-long space travel.
2. Building a spaceship with an onboard, balanced closed-cycle regenerative ecosystem that could sustain long-duration spaceflight.
3. Developing new propulsion technology to be able to achieve speeds approaching at least 10% the speed of light.

Proxima Centauri is 4.22 light years from our Solar System. That’s 40 trillion kilometers (25 trillion miles) away. The fastest moving satellite to date, the Juno probe circling Jupiter, achieves speeds of 265,000 kilometers (165,000 miles) per hour. Traveling at that speed would require a journey of 17,157 Earth years. A proposal to send a group of nanosatellites to Proxima Centauri pushed by an Earth-based laser beam could achieve speeds of 215,850,000 kilometers (134,120,000 miles) per hour which would get us to Proxima b in a little over two decades.

At 10% of light speed, a spaceship with humans aboard would need at least a century to achieve the same. Why not just twice the time? Because the nanosatellites proposal is a one way fly by with no deceleration requirement. A spaceship with a human crew onboard would need to begin slowing down well before reaching the planetary system and then would have to navigate Proxima Centauri’s solar system before inserting itself into an orbit around Proxima b. The timing of that deceleration would be an interesting challenge for those who study orbital mechanics and space navigation.

Where the Monarch Butterfly Comes In

One way for us to achieve interstellar flights of such duration is to mimic the Monarch Butterfly. Our species could be genetically re-engineered to achieve the travel in both time and distance, including resource requirements to keep us alive, by entering a stage of stasis. We don’t have to be a caterpillar to emerge as a butterfly. But cocooning or a chrysalis stage could keep us living without consuming significant resources.

How the Monarch does it is remarkable. The caterpillar in the chrysalis literally liquefies and reorganizes genetically to emerge in all its butterfly splendour. With our increasing understanding of the human genome and with tools like CRISPR, we too may one day achieve a semblance of what the Monarch accomplishes, using it to populate planets circling many distant stars. Imagine reprogramming our human DNA to make it possible to live on Mars, or Saturn’s moon, Titan, or on Goldilocks Zone planets not quite as perfect as our own. The human crew that starts the journey can undergo profound change and emerge at the end a very different and adaptable creature.

States Angelo Vermeulen, a doctoral candidate at Delft University, and founder of the DSTART project team, “In light of our insatiable appetite for exploration, it is inevitable that the human species will ultimately travel outside of the known solar system. It is the next step in human evolution.” I’m not sure in saying these words he conceived that evolution could lead to a spacefaring species with the capability to do what the Monarch butterfly does. Where DSTART has been looking at the hardware and environmental engineering requirements, others can look at genetic modification.

The Interstellar Spaceship Concept

The DSTART project involves capturing and re-engineering a large asteroid. Excavation of the interior would create a miniature world for human occupants. Excavated material would serve two purposes: to be the ink for 3-D printing the interior, and as well, to serve as propellant.

For ecosystem support, the DSTART spaceship would need a closed-cycle system. The ESA eleven-nation MELiSSA program serves as a potential model. It currently is running a demonstration laboratory at the University of Barcelona where an air-tight multiple compartment “spaceship” with a crew complement of rats has been living sustainably for months at a time. The closed-cycle system is powered by a bioreactor that sustains oxygen-and-light-producing algae which in turn is fed by the carbon dioxide exhalations of the rat crew.

I know all of this sounds like fantasy. But the rudimentary technology already exists to turn it into reality before the century ends.

For whatever reason, the topic is on my mind, and let me tell you why.

A Jet Propulsion Laboratory scientist, Anthony Freeman, presented a concept at the 2017 American Geophysical Union conference, held in New Orleans, Louisiana, on December 12th, for a 2069 interstellar mission, to take us to Proxima Centauri, our nearest neighbour. The goal would be to visit the star and its planets in search of Earth-like environments and alien intelligence. Freeman said that he and others working with NASA had been tossing around this idea for some time.

In his presentation he noted the technological impediments to such a mission:

1. The need to develop propulsion systems capable of near-light speed.
2. The need to develop deceleration capability allowing us to enter into orbit around a targeted star multiple light-years away without any human intervention.
3. The need to ensure sustainability over a century in space ensuring the viability of the instrumentation to be used upon arrival at the star system.
4. The need for communications technology able to receive data from our probe throughout its multi-light-year journey, and from it upon arrival and as it explores the worlds it encounters.

For the first challenge, a propulsion technology sufficiently fast to get us to Proxima Centauri within a century requires the development of new engines which could take the form of:

• Directed-photonic energy which would use a guided laser fired at our spacecraft to push it over several decades to achieve reasonable sub-light speed.
• A nuclear-fission engine that would set off controlled atomic bomb detonations behind the spacecraft to accelerate it in increments.
• An antimatter-matter engine which would create similar to the above-controlled detonations to accelerate the spacecraft.

What would be a reasonable attainable speed?

About 10% the speed of light or just under 108 million kilometers per hour.

To date, the fastest speeds attained by a spacecraft is 265,000 kilometers (165,000 miles) per hour. This speed has been attained by the Juno probe in its journey to and around Jupiter. At less than 0.25% of the speed we are describing for our proposed interstellar trip, that’s a far cry to go from where we are to where we want to be.

But let’s say we solve the propulsion issue and now have a propulsion system able to hit 10% sub-light speed. Now we have to consider spacecraft design. We have to give it longevity to operate over a distance and time equal to an Earth century. We will need to ensure its instrumentation will remain pristine throughout the long voyage through the near vacuum and cold of interstellar space.

And we have to make our spacecraft intelligent, if not conscious. Today artificial intelligence is not yet conscious. But it will be an important capacity of our interstellar spacecraft which will need to be wakeful as it navigates through the time and distance of interstellar space. It will have to make independent decisions should it encounter something unanticipated.

And then there is deceleration, a technology that will have to be on board the spacecraft. Could it fire a laser at an object it detects within the Proxima Centauri system that could then act as a decelerator? It won’t know about such an object until it probes the system well ahead of time, possibly several decades before arrival. And then it will have to calculate the movement of that object to fire the laser and receive the reflection back to continually decelerate. That’s not a job for a dummy. There will be no human or computer system to reference to ensure the mathematics is right.

Assuming the deceleration decision is right it could be a decade or more before the spacecraft arrives and inserts itself into orbit around the star. Then it has to make many other decisions: what to study among the objects it encounters. It needs to determine which of those objects has conditions for potential habitability. Then it needs to search for bio-signs. And finally, if bio-signs are present, it needs to search for evidence of alien intelligence including the presence of technology.

It is spacecraft with these capabilities and not starships like the fictional U.S.S. Enterprise of Star Trek that will be our interstellar explorers of the future. And as explorers and ambassadors, they will represent us in space. And if they make contact with an intelligent, technical species, it is my guess that they will most likely meet alien artificial intelligence surrogates similar to them, and not biological beings.

Why is that and why not Star Trek?

Because our Universe has a speed limit that cannot be exceeded, the speed of light. The physical limits of the speed of light at a sub-atomic level require vast amounts of energy. And subatomic particles when accelerated to near-light speed become heavier requiring increasing amounts of energy to keep them moving at a constant speed let alone an accelerating pace. So unless we find rifts in space, the wormholes of many science fiction novels, where we can bend space and time to jump across vast interstellar distances, we remain stuck at a speed that accommodates our spacecraft’s ability to travel at sub-light speeds while not accelerating to a point where its increasing heaviness impedes its progress.

A voyage to Proxima Centauri, our nearest neighbour is a century-long mission. Voyages to other stars will take far longer. There are a lot of targets as we are finding out in these last few decades. Based on the current Kepler Space Telescope‘s dataset, and from exoplanet observations from Earth-based telescopes, astronomers conclude that between 70 and 80% of the stars in our Milky Way Galaxy host one or more planets. And based on the thousands of exoplanets already known to us, the ratio of rocky to gas giants is turning out to be 1:5. Not all rocky planets have the ability to support water in all its forms on the surface. But the estimated number of such planets just in our galaxy is upwards of 100 billion. That’s a lot of territory to cover for future interstellar missions.

And in this posting, I ask a final question. When not if we encounter biological or artificial intelligence on one of these voyages of discovery, should our artificial ambassadors of humanity seek contact? Is there anything to fear if this should happen considering the enormous distances of interstellar space that will always separate us despite what science fiction writers state as possible.

The current portfolio includes:

• Interplanetary space flight habitat technology that supports astronauts while in induced deep sleep immersion (John Bradford, Space Works, Inc., Atlanta, Georgia).
• Aircraft capable of staying aloft for months serving as a stable platform for communication and Earth observation (William Engblom, Embry-Riddle Aeronautical University, Daytona Beach, Florida).
• “Solar white” coatings to be applied to fuel tanks in space to reflect and scatter sunlight keeping temperatures cold without any energy input (Robert Youngquist, Kennedy Space Center, Florida).
• Interstellar flight using micro satellites driven by directed energy beams (Philip Lubin, University of California, Santa Barbara).
• Plasmonic force propulsion to provide attitude control capability for small spacecraft with minimal power penalty and minimal mass and volume penalty (Joshua Rovey, University of Missouri, Rolla).
• Extremely large reflective telescopes made up of re-configurable elements that can grow to 10 times the size of Hubble and be deployable in space (Melville Ulmer, Northwestern University, Evanston).
• A Plasma aerocapture and entry system to provide drag for braking in human and robotic spacecraft missions to solar system planets (David Kirtley, MSNW, Redmond).
• A rotating in-space habitat with a built-in robotic construction system to expand it (Robert Skelton, Texas Engineering Experiment Station, La Jolla).

The images below beginning at the top left going left to right follow the sequence of the projects as described above.

This is pretty “cool” stuff and each of these projects has passed through Phase I and onto Phase II. Two years from now the developers will report their successes or failures to NASA. Then the real interesting next phase begins with even more money being applied to turn these research and laboratory concepts into future build and launch dates.

That means there maybe a loophole in the laws of physics that allows an object to move faster than light speed. As scientists conjecture a spaceship could fold space-time around it forming a doughnut-shaped bubble that would ride through space like a surfboard on a wave and travel at speeds exceeding that of light. This would require the manipulation of dark energy,  a mass-energy force representing 74% of the Universe.

Scientists of the Big Bang have theorized that shortly after the Universe began matter exceeded the speed of light. And since light and matter go along together as the Universe expands there is evidence that space-time expansion can exceed light speed. You can blame string theorists for the explanation and for devising, theoretically, a way to manipulate dark energy to accelerate a spaceship. This is called an Alcubierre warp drive, named after physicist Miguel Alcubierre who first suggested it in a paper entitled, “The Warp Drive: Hyper-fast travel within general relativity.”

At last week’s symposium NASA physicist Harold White, presented a refined view of the Alcubierre warp drive that theoretically could wrap around a mass equivalent to 725 kilograms (1,600 pounds). When Alcubierre first proposed his warp drive concept the mass-energy requirement equaled a planet the size of Jupiter.  Alcubierre described an exotic matter possessing strange properties that would allow the spaceship to occupy a spherical bubble with space contracted in front of the ship and expanded behind it (click here to watch a video explanation). Everything within the bubble would be time constant. White’s bubble is flattened to a doughnut shape and he proposes an oscillating space bubble to further reduce the energy requirements of creating a warp field.

As White envisages it, in the future we will leave the gravity well of Earth and travel a distance away from the planet. Then we will engage the drive to create our warp field and head off to Proxima Centauri traveling at speeds that could get us there in weeks. Compare that to light which would take 4.22 years. And then compare it to Voyager 1 now on the edge of the Solar System and its 81,000 year journey to reach the same destination.