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Planetary Protection in an Interstellar Mode

Back in 2013, Heath Rezabek began developing a series in these pages on a proposal he called Vessel, which he had first presented at the 100 Year Starship Symposium in September of 2012. A librarian and futurist, Rezabek saw the concept as a strategy to preserve both humanity’s cultural as well as biological heritage, with strong echoes of Greg Benford’s Library of Life, which proposed freezing species in threatened environments to save them. In Heath’s case, a productive partnership with frequent Centauri Dreams contributor Nick Nielsen led to articles by both, which produced a series of interesting discussions in the comments.

I noticed in Philip Lubin’s new paper, discussed here on Friday, an explicit reference to the idea of interstellar craft as possible backup devices for living systems. Lubin singled out the Svalbard Global Seed Vault (styled by some the ‘Doomsday Vault’), which preserves seed samples numbering in the millions, with the aim of keeping them safe for centuries. Here too we have the idea of protecting fragile living systems from existential risk in the form of what Lubin refers to as a ‘genetic ark,’ meaning that while his paper looks at tiny ‘wafer’ probes capable of carrying microorganisms, future iterations might develop into another kind of Earth backup system.

Is interstellar flight in future centuries to become the vehicle for preserving our planet’s heritage and scattering copies of ideas and organisms through the universe? It’s a persuasive thought. Here’s how Lubin and team describe it:

In addition to the physical propagation of life, we can also send out digital backups of the “blueprints of life”, a sort of “how-to” guide to replicating the life and knowledge of Earth. The increasing density of data storage allows for current storage density of more than a petabyte per gram and with new techniques, such as DNA encoding of information, much larger amounts of storage can be envisioned. As an indication of viability, we note the US Library of Congress with some 20 million books only requires about 20 TB to store. A small picture and letter from every person on Earth, as in the “Voices of Humanity” project, would only require about 100 TB to store, easily fitting on the smallest of our spacecraft designs. Protecting these legacy data sets from radiation damage is key and is discussed in Lubin 2020 and Cohen et al. 2020.

Image: How much can we ultimately preserve of Earth? And if we eventually can build large-scale arks, where will we send them? Credit: Adam Benton.

Protecting Planets Beyond Our Own

I’m heartened by two things in this paper. The first is, as I mentioned Friday, the consideration of how to use deep space technologies in the service of biology, a field usually discussed in the interstellar community only in terms of biosignatures from exoplanet atmospheres. If we are at the beginning of what may eventually become an interstellar expansion, we should be thinking practically about what future technologies can do to enhance both the preservation of and adaptation of biological systems to deep space. The need for this kind of study is already apparent as we contemplate the possibility of future off-world colonies on the Moon or Mars.

It’s also heartening to see the thread of knowledge preservation mixing with thinking on biological preservation in the event of future catastrophe. If something goes desperately wrong on our home world — plug in the scenario, from nuclear war to runaway AI or nanotech — we need to be able to save enough of our species to rebuild, either here or elsewhere. If here, then archival installations in nearby space could complement those on Earth. If elsewhere, we can hope to scatter knowledge and biological materials widely enough that some may survive.

This concept, however, runs into the question of planetary protection, given that we already have a deep concern about contaminating places we visit with our spacecraft. There are guidelines in place, as the Lubin paper notes, under Article IX of the Outer Space Treaty in the form of Committee on Space Research (COSPAR) regulations. At present, these extend only to Solar System bodies, and include the problem of contamination from Earth as well as contamination from other bodies via sample return materials brought back to our planet.

If we ever reach the point where realistic travel times to other stars become possible, we’ll confront the issue in exoplanet systems as well. It’s a big topic, too big to handle here in the time allowed, but it’s interesting how Lubin and colleagues discuss it in terms of the tiny probes they contemplate sending out beyond the heliosphere. The problem may be resolved within the mission profile. From the paper:

An object with a mass of less than ten grams accelerating with potentially hundreds of GW of power, will, even if it were aimed at a planetary protection target (for example Mars), enter its atmosphere or impact the solar system body with enough kinetic energy to cause total sterilization of the biological samples on board. The velocity of the craft would thus serve as an in-built mechanism for sterilization. The mission profile does not include deceleration, so this mechanism is valid for the entirety of the mission.

We can add to this the fact that Starlight envisions craft aimed at targets outside the ecliptic, significantly lowering the chances of impact with a planet. If current requirements call for demonstrating probabilities of 99% to avoid impact for 20 years and 95% to avoid impact for 50 years, these requirements seem to be met by the kind of craft Starlight contemplates. The kinetic energy of one of these wafer craft moving at a third of the speed of light is roughly 1 kiloton TNT per gram, according to the authors, which would vaporize craft and payload.

If we go interstellar, though, other issues emerge. All that kinetic energy falls into a different light if we imagine an interstellar flyby probe slamming inadvertently into a planetary atmosphere. If the effect would be little more than that of an arriving large meteorite, we still face the question of affecting an environment. There is more to contamination than a biological question, and it’s obvious that any future interstellar capability will demand a rethinking of regulations governing how our presence makes itself known to any local life forms. We have plenty of time to ponder these matters, but it’s good to see they’re already on the radar in some quarters.

On this score, Lubin and team point to a 2006 paper in Space Policy by C.S. Cockell and G. Hornbeck called “Planetary parks-formulating a wilderness policy for planetary bodies” (abstract). Here questions of planetary protection mingle with what the authors call “utilitarian and intrinsic value arguments.” The need to preserve an exoplanet’s pre-existing environment is a major theme in this work, one that I want to explore in a future post.

The paper on Starlight is Lantin et al., “Interstellar space biology via Project Starlight,” Acta Astronautica Vol. 190 (January 2022), pp. 261-272 (abstract).

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{ 10 comments… add one }
  • Alex Tolley October 26, 2021, 10:24

    We should be very cautious in making assumptions that DNA, or even frozen eggs/embryos can be used to recreate species. Mammals, birds (possibly/probably dinosauria), and any species requiring parenteral or group culturing cannot be ressurrected in isolation. Humans are the prime example, and would require android “parents” to be given the needed upbringing. In practice animals also need genetic diversity in a wild environment so more than one genome must be stored if the genetic approach is used. Frozen fertilized eggs and simple organisms can be used where the species requires no parenting, so perhaps organisms as complex as reptiles might work. However there is also the complication of microbiomes and environmental bacteria. For example legumes need nitrogen fixing bacteria . Abyssal living squid with bioluminescent organs need certain bacteria to attract prey and mates. Put a squid in a sterile exoplanet ocean and it would quickly die even if food prey was also present.

    Noah’s mythical ark would be a better method than storing DNA or frozen eggs/embryos for seed ships as the ark could theoretically recreate ecosystems which seed ships would only have a very limited ability to do.

    • DCM October 27, 2021, 4:06

      Any newly made world would have to start with the simplest organisms.
      The process will take a long time and of course life there will continue to evolve. But it should be done.

      • Alex Tolley October 27, 2021, 11:02

        Either you are missing my point or side-stepping it by moving the goal posts. I am not saying that we could quickly create a terrestrial ecosystem like the claims in the Biblical story of Genesis. What I am saying is that we cannot create ecosystems by mimicking those on volcanic islands where plants and animals from elsewhere arrive. My point is that a seed ship is not the equivalent of that external biosphere. It cannot create some life forms unless it contains higher animals in some state – IOW it is no longer a seed ship. A ship carrying just DNA strands and relevant food sources, or even worse a digital reference and DNA strand constructor.

        We see this fantasy in movies where clones can be made ( with convenient rapid aging) that have the same memories as the original. We see it in the movie “Forbidden Planet” where there are manufactured terrestrial animals on Altair IV (by Morbius’ use of the Krell technology?).

        We can jump start a biosphere with complex organisms but even here, insects that require no parenting may require the correct foods to survive. Many insect species are adapted to specific food sources, and others require certain environmental conditions – day length, seasons, a moon, etc., etc. volcanic islands build their own ecosystems with time based on the plants and animals that are not too specialized, but evolve specialized forms much later, after millions of years.

        If humanity does embark of a life seeding program in the galaxy, it will be a very long term project, probably longer than biological humans exist. Without some unforeeable new technology, I don’t see how we could recreate suitable terraformed planets within 1-10 millennia unless we can accept very simplified ecosystems absent the charismatic megafauna that we often associate with terrestrial ecosystems.

        • charlie October 27, 2021, 17:51

          ” We see it in the movie “Forbidden Planet” where there are manufactured terrestrial animals on Altair IV … ” (they weren’t manufactured, they were brought there by the Krell ).

          • Alex Tolley October 27, 2021, 21:31

            Thank you for the correction. It proves my point regarding megafauna – they must be brought already nurtured, not as eggs or embryos.

  • Ricardo L. Garcia October 26, 2021, 14:19

    Interesting theme, as usual. And it definitely picked my curiosity to see your “Now Reading” book–I think I may try it. Meanwhile, I used a https://www.amazon.com/time-phoenix-man-ricardo-garcia/dp/1492809993/ref=pd_rhf_dp_p_img_2?_encoding=utf8&psc=1&refrid=h31hbcsvrhs9q97511c1different concept in my TIME OF THE PHOENIX MAN, t.e. nanobots.

  • Thomas R Mazanec October 27, 2021, 10:41
  • Geoffrey Hillend October 27, 2021, 17:31

    Wafer like objects with less than ten grams don’t have much of a shield against the cosmic rays and x and gamma rays. The DNA might get damaged. I don’t t think that sending DNA or eggs can be of any harm even if they did somehow slowdown and survive re entry and impact. The idea of cloning a fertilized egg without a womb may be impossible. Even hardy Viruses might not make the trip, so the ship should really be a lot larger for radiation shielding which is briefly mentioned. Consequently, the spacecraft has to be much larger for radiation shielding, so we might as well send live animals and people.

  • FrankH October 28, 2021, 14:45

    “Existence” by David Brin has alien artifacts launched by various civilizations in attempt to preserve their culture and individuals… although in the story they’re closer to interstellar spam.

  • gbaikie October 28, 2021, 19:09

    We don’t know if human life can live on Mars.
    Or do humans need Earth’s gravity.
    We don’t know if artificial gravity is the same as natural gravity.
    We should test if artificial gravity is equal to effects of gravity.
    Since NASA plans to send humans to Mars, NASA should build a station with an artificial gravity of Mars and have it crewed for months and see what the effects are. Because it’s going to send crew to Mars “fairly soon”. It could be that the results are not conclusive- artificial gravity of Mars, might be same as living on Mars with Mars gravity. But it could be “close enough” and if crew stay on station for 3 or 6 month, one can compared it to 3 or 6 months stays on ISS.
    If Mars natural gravity is close enough to Earth gravity and Mars has a lot underground areas, it seems Mars could be used as Ark for life on Earth. And if low gravity of Moon, works, the Moon also have lots natural underground spaces. Of course another thing is developing life that live in low lunar gravity condition and/or live in artificial gravity environments.

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