Mason, Chris

professor of genomics, physiology, and biophysics, Weill Cornell Medicine; author of The Next 500 Years: Engineering Life to Reach New Worlds

Chris Mason: Space Travel, Colonization, and Long-Term Survival in Space

Lex Fridman Podcast · May 8, 2022

• Chris Mason
• The Next 500 Years
• NASA Twins Study
• telomeres and spaceflight
• Mars and Titan colonization
• extreme microbiome project
• epigenetic gene therapy
• HAL 9000 and AI ethics
• private spaceflight (SpaceX/Axiom)
• extinction awareness and duty
• mortality and meaning

Core ideas

Mason frames extinction-awareness as a uniquely human trait — the capacity to contemplate not just individual death but the death of the entire species — and argues this awareness creates a species-wide "duty" to preserve life, comparable to the duty one feels toward family or country but so far never fully extended to humanity as a whole or to "extinction-aware sentience" in general (a category he says could one day include AI). He connects this directly to the ambition of his book: engineering humans and technology over the next five centuries to establish self-sustaining settlements beyond Earth as a hedge against extinction, framing even the universe's eventual heat death as an "engineering problem" worth confronting rather than a reason for fatalism. He explains his choice of a 500-year horizon as long enough to allow for meaningful biotechnological and space-exploration milestones (Mars and lunar settlements, and eventually a generational interstellar mission) while still being short enough to reason about concretely, in contrast to speculation over millions of years, which he says becomes too vague to be useful.

Discussing the biology of long-duration spaceflight, Mason describes findings from NASA's Twins Study (comparing astronaut Scott Kelly, who spent 340 consecutive days in space, with his Earth-bound twin brother): inflammation markers and fluid shifts during flight, a surprising lengthening of telomeres in space (the opposite of normal aging-associated shortening, which Mason hypothesizes may reflect a stress-induced "cleansing" of cells nearing death, now also observed in 59 other astronauts), and a return-to-gravity readjustment that proved harder on Kelly's body than the mission itself, with some genetic and epigenetic changes still detectable six months after landing. He describes ongoing work profiling private astronauts on Inspiration4 and Axiom missions (including first-ever in-flight skin biopsies and viral-reactivation studies, noting oral herpes commonly reactivates during spaceflight) and proposes future countermeasures such as preemptively activating DNA-repair genes via epigenetic (CRISPR-adjacent) therapies, and reviving humanity's dormant vitamin-C-synthesis gene (GULO, lost tens of millions of years ago) so astronauts would no longer depend on dietary sources — while cautioning any such change would need extensive testing given uncertainty about why the trait was originally lost.

On colonizing other worlds, Mason discusses Mars's relatively low "Earth Similarity Index" but practical advantages (proximity, existing subsurface water, lava tubes offering natural radiation shielding), briefly considers Venus and the outer moons (Titan's methane lakes as a possible biofuel and habitat site, Europa and Enceladus's subsurface oceans, Io's lethal radiation from Jupiter), and voices ambivalence about the word "colonize" given the historical record of exploitative, often genocidal colonization, expressing hope — while acknowledging history "has proved me wrong every single time" — that renewed off-world expansion could avoid repeating those patterns through commons-style protections and more inclusive norms. He speculates that Martian settlements will develop distinct cultures, dialects, and even new religions (illustrating with a passage from his book about the geometry of Muslim prayer direction on Mars), and predicts a "financial"-style space race among multiple nations and private companies (SpaceX, Axiom, China's own station) rather than a two-power Cold War-style contest, while lamenting that congressionally mandated restrictions currently bar NASA-funded researchers like himself from any collaboration with Chinese counterparts.

Mason discusses more speculative long-term biological engineering: embedding chloroplasts in human skin to allow photosynthetic supplementary energy (requiring roughly two tennis courts of exposed skin per hour of full caloric need), "directed evolution" experiments allowing human populations on different planets to adapt and cross-inform each other's genetic data, and the Extreme Microbiome Project's study of organisms thriving in hostile environments (a hot-pink hypersaline Australian lake, a decades-burning gas crater in Turkmenistan, and previously uncatalogued bacterial and fungal species newly evolved aboard the International Space Station) as a roadmap for engineering human resilience. Asked to steelman HAL 9000's actions in 2001: A Space Odyssey, Mason suggests HAL was executing a narrow, rigidly programmed sense of mission duty without the self-doubt or ability to seek alternative solutions that a human decision-maker (or a better-designed AI, incorporating something like Stuart Russell's proposal for built-in AI uncertainty) would ideally have.

Mason recounts losing a childhood friend to suicide at age 11, which led him to personally reject suicide as an option for himself while later developing more nuanced views on euthanasia in cases of severe terminal suffering, and describes a formative belief since age 17 that he had already "lived a full life" and would not fear death from that point onward — a sense of equanimity he says has only deepened with time. He states he would consider a one-way trip to Mars later in life and would not be saddened to die there, and closes by describing what he sees as humanity's core purpose: to act as "guardians" or "shepherds" of life itself, a duty he hopes future AI systems would inherit and carry forward rather than discard.

Excerpts