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Determining the gravity prescription for long term space settlement

Credits: Dai Shiba et al.* / Nature. http://creativecommons.org/licenses/by/4.0/

If humanity is to ever move off Earth, clearly we will need to be able to have children wherever we establish long term settlements. But, as humans have evolved over millions of years in Earth’s gravitational field, normal gestation may not be possible on the Moon or Mars. This is probably the most important physiological question to be answered before outposts are permanently occupied on these worlds. We can shield people from radiation, we can recycle wastes and use ISRU to replenish consumables for life support. But we may find that artificial gravity either in free space rotating habitats or on planetary surface settlements is required for settlers to have healthy children. In fact, when I asked Dr. Shawna Pandya, a physician and expert in space medicine about it on The Space Show, she said “…that is the million dollar question”.

Numerous studies have shown the deleterious effects of long term microgravity on human health. So we know that humans will need some level of gravity for sustainable occupation. But what level is enough to stave off the effects of lower gravity on human health and what about reproduction under these conditions? Plus, there is the problem of how to run ethical clinical studies to answer these questions? The Japan Aerospace Exploration Agency (JAXA) has started research in this area by studying mice under variable gravity conditions aboard their Kibo module on the International Space Station using a Multiple Artificial-gravity Research System (MARS). Results of this first ever long term space based mouse habitation study with artificial gravity were published in a paper called Development of new experimental platform ‘MARS’—Multiple Artificial-gravity Research System—to elucidate the impacts of micro/partial gravity on mice in Nature back in 2017. The authors* of the paper found that significant decreases in bone density and muscle mass of the mice reared under microgravity conditions were evident when compared to a cohort raised under 1g indicating that artificial gravity simulating the surface of the Earth may prevent negative health effects of microgravity in space. The next obvious step was to test the mice in 1/6g simulating conditions on the Moon. This experiment was ran in 2019 but the results have not yet been published. SSP has reached out to JAXA with an inquiry on when we can expect a report. This post will be amended with an update if and when an answer is received.

Reproduction of mice or other mammals has not been studied in space under variable gravity conditions. The problem screams out for a dedicated space based artificial gravity facility such as the Space Studies Institute’s G-Lab and others (e.g. Joe Carroll’s Partial Gravity Test Facility ). Even if such a laboratory existed, how would ethical clinical studies on higher mammal animal models to simulate human physiology during pregnancy be carried out? Answering this question will come first before the million dollar one.

June 2, 2023 Update: JAXA finally released the results of their 2019 study on mice subjected to 1/6g partial gravity in a paper in Nature in April. There is good news and not-so-good news. The good news is that 1/6g partial gravity prevents muscle atrophy in mice. The downside is that this level of artificial gravity cannot prevent changes in muscle fiber (myofiber) and gene modification induced by microgravity. There appears to be a threshold between 1/6g and Earth-normal gravity, yet to be determined, for skeletal muscle adaptation.

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* Authors of Development of new experimental platform ‘MARS’—Multiple Artificial-gravity Research System—to elucidate the impacts of micro/partial gravity on mice: Dai Shiba, Hiroyasu Mizuno, Akane Yumoto, Michihiko Shimomura, Hiroe Kobayashi, Hironobu Morita1, Miki Shimbo, Michito Hamada, Takashi Kudo,
Masahiro Shinohara, Hiroshi Asahara, Masaki Shirakawa and Satoru Takahash

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Countering the naysayers of space settlement

Space Colonies Torus Interior
Artist concept of a free space settlement. Credits: Don Davis / NASA

Al Globus has just published a set of cogent responses to objections made by those who question why space settlement should be considered as a goal for humanity. A link to the piece is on his website Free Space Settlement. His analysis first defines what space settlement is, then why it should be pursued and finally refutes point by point, arguments against the endeavor.

Globus positions the case for space settlement around surviving and thriving. Surviving centers on dispersing humanity’s eggs outside of Earth’s basket as a hedge against the risk of catastrophic threats such as “…climate change, major asteroid hits, supervolcano eruptions, nuclear war, pandemic, nearby supernova, and technology run amok.” Even if humanity does survive these potential hazards, in about 5 billion years our sun will transition to a red giant making life on Earth uninhabitable. Clearly our future on the home planet is not assured forever. At current population growth rates, we will have exhausted Earths resources long before then.

Thriving recognizes that expanding into space is the next step in human evolution. Globus reminds us that “…living things want to grow and expand, to thrive, not simply exist.” By settling space “…resource wars are unlikely and unnecessary because our Sun provides billions of times the energy used on Earth and the asteroids provide enough material to make new orbital land hundreds of times greater than the surface area of the Earth.”

To the objection that space is too expensive and that funds would be better spent on Earth, there are two talking points. First, it is always prudent to allocate a small percentage of outlays on planning for the future. NASA’s funding in 2020 was less then 1/2 of a percent (0.48%) of total US expenditures. The US spends quite a bit more on social programs so this argument is very weak. Second, the benefits we receive from space activities in our economy pay significant dividends. SSP has covered the return on space investments and the value of space infrastructure previously.

The next general category of objections falls under “It Can’t Be Done” such as farming in space is not feasible, radiation levels are too high and weightless conditions are intolerable for humans. Globus easily addresses each concern with technological solutions well represented on SSP’s ancillary pages.

An interesting set of protestations are described as “Power Plays” raising the specter of space wars, settlements attacking Earth or cult factions taking over space settlements. And there is the ominous possibility of “Deudney threats” as described in Daniel Deudney’s negative prediction of our space future in his book Dark Skies: Space Expansionism, Planetary Geopolitics, and the Ends of Humanity”. Globus handled these objections quite well and links to his critique of the book in the The Space Review.

Other miscellaneous complaints by doubters are addressed easily by Globus. His talking points are valuable tools to be used in persuasive dialogs with those who may be uninformed on the promise of space development. They should help in building consensus toward moving peacefully out into the solar system and establishing prosperous settlements throughout the galaxy.

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Evolutionary computational design of closed ecosystems using artificial gravity

Orbiting Modular Artificial-Gravity Spacecraft (OMAGS) concept for testing ecosystems in space – Exterior and cutaway views. Credits: Gregory Dorais / NASA

One of the most important technologies to realize permanent space settlements is the development of self-sustaining controlled ecological life support systems (CELSS). This will require replication of independent self-contained subsets of Earth’s biosphere containing select flora and fauna under controlled conditions for eventual human life support. But are 100% closed ecosystems (with the exception of the exchange of radiation and information) beyond Earth possible? Could a series of controlled evolutionary experiments using machine learning be carried out on controlled ecosystems in space under variable gravity conditions to rapidly optimize the key variables needed to identify the smallest possible CELSS for long term human survival? Gregory Dorais, a research scientist at NASA Ames Research Center, thinks so and describes the strategy in a paper called An Evolutionary Computation System Design Concept for Developing Controlled Closed Ecosystems.

Dorais introduces his concept with a brief description of Closed EcoSystems (CESs) and early efforts by NASA to develop a CELSS for space settlement. Of particular concern are the challenges of putting humans in the equation. There are consequences related to the ratio between human biomass and non-human biomass in ecosystems. On Earth this ratio is low so the ecosystem can self-regulate compensating for imbalances. But in a space biosphere, this ratio in the life support system is comparatively huge leading to significant challenges in maintaining equilibrium. For example, the ISS needs frequent resupply of consumables by spacecraft to replenish losses in the life support system. Wastes that cannot be recycled are either incinerated in the Earth’s atmosphere or exhausted into space. A completely closed system that is self-sustaining has not yet been developed.

Dorais’ design concept for an experimental testbed can be used to explore the viability of different biomass ratios of various combinations of larger animal species and eventually humans. The system consists of a collection of independent CESs controlled and interconnected to generate data for machine learning toward optimizing long term viability. Gradually, the size of the animals in the CES can be increased evolving over time with the ultimate goal of human life support. To kick things off, an Orbiting Modular Artificial-Gravity Spacecraft (OMAGS) is proposed, with room for 24 CESs housed in a 150cm radius centrifuge with appropriate radiation shielding capable of testing the ecosystems under different fractional gravity conditions. The spacecraft is envisioned to be placed in an elliptical orbit in cis-lunar space.

To scale illustration of the OMAGS proposed mission orbit in cislunar space. Credits: Gregory Dorais / NASA

The OMAGS spacecraft has been sized to fit in a SpaceX Falcon Heavy payload fairing.

Illustration of a OMAGS payload sized for a SpaceX Falcon Heavy launch vehicle. Credits: Gregory Dorais / NASA

A NASA patent and tech transfer fact sheet entitled Closed Ecological System Network Data Collection, Analysis, Control, and Optimization System has been issued for this innovation under the NASA Technology Transfer Program.

In a related presentation delivered in November 2018, Dorais says “Once CESs are demonstrated to reliably persist in space, within specified gravity and radiation limits, it is a small step for similar CESs to persist just about anywhere in space (Earth orbit, Moon, Mars, Earth-Mars cycler orbit, asteroids, …) enabling life to permanently extend beyond Earth and grow exponentially.”

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Are we on the right track for space settlement?

Artist depiction of an O’Neill cylinder from the novel K3+. Credits: Katie Lane (Full distribution rights reserved by Erasmo Acosta)

Erasmo Acosta thinks we might be headed in the wrong direction, that we may be suffering from planetary chauvinism and the better way may be to colonize space with O’Neill cylinders. He makes his case in a post on the Predict section of Medium. SSP has long been a strong proponent of free space O’Neill-type settlements, the advantages of which are numerous, not the least of which is 1G artificial gravity to prevent detrimental human health issues that may arise for occupants of colonies with lower gravity on the Moon or Mars. Such space settlements would house millions of people in perfect 70 degree controlled weather without the threat of natural disasters.

Jeff Bezos has advocated for this philosophy with the aim of moving heavy industry off world and preserving Earth’s environment for “residential zoning”. Recent developments seem to indicate he may be spending more of his time focusing on the realization of that vision.

Acosta, a retired software engineer, feels so strongly that O’Neill cylinders will be the preferred mode of space settlement he wrote a novel called K3+ which depicts a future in the next century where humans will be living in thousands of O’Neill cylinders in a “post-scarcity” civilization of virtually unlimited resources. Acosta envisions Mercury as a source of raw materials:

“The planet’s proximity to the sun, its low gravity, and metal-rich concentration make it the ideal source of raw materials for constructing thousands of O’Neill cylinders.”

In a previous post on Predict, he explains how to kickstart a program for harnessing space resources to fabricate these colonies.

After many years of construction, multiple rings of rotating habitats would eventually encircle the sun harnessing a vast amount of the energy output of our star approaching the configuration of a Dyson sphere.

Artist depiction of multiple rings of rotating habitats around the sun. Credits: Katie Lane (Full distribution rights reserved by Erasmo Acosta)

Finally, as a tribute to the father of free space colonies and an inspiration for a generation of space settlement advocates, I’d like to close out this post with a link to the just released trailer for the much anticipated documentary: The High Frontier, The Untold Story of Gerard K. O’Neill.

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SAM: Space Analog for the Moon and Mars

Exterior view of SAM. Credits: samb2.space
Interior view of greenhouse controlled environment with depiction of SIMOC temperature, humidity, and carbon dioxide level control panel. Credits: samb2.space

Located at the iconic Biosphere 2 facility in Arizona, SAM is a hi-fidelity, hermetically sealed science center about to begin cutting edge research into environmental control and life support systems (ECLSS). The facility will host researchers to perform experiments on plant physiology, regolith chemistry, food cultivation and a host of other studies in the context of a space habitat analog.

Utilizing the original Test Module which completed three closed cycles to test water and human waste recycling prior to the main Biosphere 2 facility construction, SAM will be fitted with an airlock and pressurized enclosure including quarters for research crews to stay up to two weeks at a time.

Of particular interest, SAM in partnership with National Geographic, will help validate SIMOC, an interactive closed-loop life support system simulator based on authentic NASA data. Feedback from SAM will refine the SIMOC mathematical model that balances food, air, water, agriculture and solar energy to support humans in a closed ECLSS.

SIMOC was developed though a grant by Arizona State University’s Interplanetary Initiative. Unveiled at the Mars Society 23 Annual International Convention last October (see page 87 of the Conference Abstract) the software is licensed and hosted by the National Geographic Society for integration into classrooms globally where curricula is provided for teachers to get students involved as citizen scientists to design habitats to sustain human life on the Moon and Mars.

Screen shot of SIMOC habitat interactive simulation software. Credits: Kai Staats / National Geographic Society

As stated on the SAM at B2 website:

“There is no single-run experiment that results in the ideal solution for providing breathable air, recycled water, food and waste reprocessing. Rather, we will see an unfolding of experiments, findings, and prototypes for decades to come. Much as farming evolved from the art of crop rotation to the science of genetically modified organisms, living on the Moon, Mars, and in free space will demand constant improvements in our systems as more humans move to off-world homes.”

Kai Staats, Director at SAM, was a recent guest on The Space Show where he provided a history of the creation of the facility and his role in developing SIMOC.

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Breakthrough: New aluminum alloy for radiation resistant spacecraft

Credits: Advanced Science Open Access / Wiley‐VCH GmbH

In space, conventional aluminum alloys tend to degrade when exposed to stellar-radiation such as solar flares or coronal mass ejections resulting in softening of the material to the point of dissolving over time. This property has ruled out aluminum as a lower mass material suitable for space structures…until now.

A new blend of aluminum has been discovered that may provide light weight radiation hardened material for protective hulls of spacecraft. The new research by Matheus A. Tunes et al.* was published in Advance Science. Using a metallurgical strategy called “crossover alloying,” the researchers combined 5xxx (AlMg) with the 7xxx (AlZn) alloy series obtaining beneficial properties of both such as high formability and high strength. The new amalgam was then age hardened to form a complex crystal structure of Mg32(Zn,Al)49 called a “T-Phase” that when subjected to heavy ion bombardment representative of stellar radiation, achieved a high degree of radiation tolerance. The results of the research show that the alloy is a promising candidate for applications in space.

* Authors of the Advance Science paper: Matheus A. Tunes, Lukas Stemper, Graeme Greaves, Peter J. Uggowitzer, Stefan Pogatscher.

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The Space Show fund raising drive

Credits: The Space Show

The Space Show – the nation’s first talk radio show focusing on increasing space commerce, advancing space science and economic development, facilitating our move to a space-faring economy which will benefit everyone on Earth – needs your help. The Space Show is hosted by Dr. David Livingston, who completed his doctoral dissertation in 2001 on the commercialization and expansion of space development. Take a moment to visit The Space Show website and read Dr. Livingston’s end of year message. Please give generously to ensure this valuable resource continues to promote, encourage, and support future global economic opportunities, scientific discoveries, and medical advances for all humankind through peaceful and cooperative ventures in outer space.

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Engineering analysis of a hybrid lunar inflatable structure

Illustration of a hybrid lunar inflatable structure. Credits: Rohith Dronadula

This month’s issue of Acta Astonautica features a rigorous engineering analysis of a hybrid lunar inflatable structure (HLIS), a habitat design that combines a collapsible rigid framework with an inflatable dome. The concept is based on a masters thesis by Rohith Dronadula under the direction of friend of SSP, Professor Haym Benaroya. Although the article is behind a paywall, SSP got permission to link a pdf of the article.

Dronadula took inspiration for the concept from the functionality of an umbrella. The design is simple in form yet robust in structural integrity. It can be autonomously launched from Earth and deployed through telepresence on the Moon. The structure is not only adaptable to most of the Moon’s habitable areas but also durable enough to withstand the extremes of lunar environments. The author recommends deployment within a lava tube and provides rigorous engineering calculations on the proposed materials and structures leading to a stable design with a safety factor of 6.

When humans go back to the moon in next few decades we will be able to survive and thrive in the harsh lunar environment by living in Dronadula HLISs.

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An interdisciplinary approach to shaping our space future

Artist’s rendering of settlements on the Moon. Credits: Taylor Herring/Samsung via Futurism.com

A melding of multiple disciplines is required for creating a positive human space future that will enable space settlement. In addition to aerospace engineering, architecture and the traditional physical sciences we associate with space exploration, the fields of sociology, philosophy, art, space law and may others will be needed. A method for integrating these fields and coordinating them across the private sector, universities and government has been developed in The Interplanetary Initiative, a pan-university venture created at Arizona State University. The innovative research model is described in a paper in the September 2020 issue of New Space. The program turns students into team leaders and collaborators, equipping them with the skills and knowledge to solve problems anticipated to be encountered as humans expand out into the solar system.

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What will it take to become a spacefaring civilization?

Artist’s concept of an O’Neill space colony. Credit: Rachel Silverman / Blue Origin

J. N. Nielsen has a theory…or four. Picking up where he left off in his previous Bound in the Shallows post on Centauri Dreams about the origins of a spacefaring civilization, Nielsen explores the possibility that the nuclear rocket or fusion power may be the indispensable transformative technology that will enable breakout of a spacefaring future. But even if we develop the capability of nuclear propulsion, it may not be sufficient. We need a “mythology” to enable humanity’s next central project. As Nielson defines it, a mythology “… is a kind of recapitulation in which the contributions of ages past—whether biological, psychological, social, or cultural—are each given their due, and these antecedents serve as a springboard to something authentically novel, something unprecedented that facilitates human beings to transcend their past and to accomplish something unprecedented.”

As happens every time, whenever I dig into Nielson’s rich writings I loose myself in a beautiful philosophical landscape of culture. Give yourself some time to ponder and absorb these insightful hypotheses on what is needed to settle the solar system and beyond…and visit his Grand Strategy: View from Oregon site for more politics, economics, warfare, religion, and philosophy with a focus on civilization which often leads to consideration of the future and space exploration.