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Starlight: Toward an Interstellar Biology

If you could send out a fleet of small lightsails, accelerated to perhaps 20 percent of the speed of light, you could put something of human manufacture into the Alpha Centauri triple star system within about 20 years. So goes, of course, the thinking of Breakthrough Starshot, which continues to investigate whether such a proposal is practicable. As the feasibility study continues, we’ll learn whether the scientists involved have been able to resolve some of the key issues, including especially data return and the need for power onboard to make it happen.

The concept of beam-driven sails for acceleration to interstellar speeds goes back to Robert Forward (see Jim Benford’s excellent A Photon Beam Propulsion Timeline in these pages) and has been examined for several decades by, among others, Geoffrey Landis, Gregory Matloff, Benford himself (working with brother Greg) in laboratory experiments at JPL, Leik Myrabo, and Chaouki Abdallah and team at the University of New Mexico. At the University of California, Santa Barbara, Philip Lubin has advocated DE-STAR (Directed Energy Solar Targeting of Asteroids and Exploration), a program for developing a system of modular phased laser arrays that could be used for asteroid mitigation and as propulsion for deep space missions.

Out of this grew Directed Energy Propulsion for Interstellar Exploration (DEEP-IN), which homes in on using tiny wafer probes for interstellar travel. Also known as Starlight, the program is now the subject of a paper in Acta Astronautica that takes interstellar mission concepts into the realm of biology. Working with Stephen Lantin and a team of researchers at the UCSB Experimental Cosmology Group, Lubin is examining how we can use small relativistic spacecraft to place seeds and microorganisms for experimentation outside the Solar System.

Image: Initial interstellar missions will require a complete reevaluation and redesign of the space systems of today. The objective of the Wafer Scale Spacecraft Development program (WSSD) at the University of California Santa Barbara (UCSB) is to design, develop, assemble and characterize the initial prototypes of these robotic platforms in an attempt to pave a path forward for future innovation and exploration. This program, which is just one venture of the UCSB Experimental Cosmology Group’s Electronic and Advanced Systems Laboratory (UCSB Deepspace EAS), focuses on leveraging continued advances in semiconductor and photonics technologies to recognize and efficiently address the many complexities associated with long duration autonomous interstellar mission. Credit: UCSB Experimental Cosmology Group.

Biology Beyond the Heliosphere

The goal of Starlight is not to seed the nearby universe — that’s an entirely different discussion! — but to conduct what the paper calls ‘biosentinel’ experiments, sending them not to another star but to empty interstellar space to help us characterize how simple biological systems deal with conditions there. This could be seen as a step toward eventual human travel to other stars, but the paper doesn’t dwell on that prospect, wisely I think, because what we learn from such experiments is vital information in its own right and may teach us a good deal about abiogenesis and the possibility of panspermia as a way of scattering life throughout the cosmos.

We may, in other words, be able to characterize biological systems to the point where we understand how to protect human life on a future interstellar mission, but the goal of Starlight is to begin the experimentation that will tell us what is possible for living systems under a wide variety of conditions in deep space. Such missions are, in effect, scouts. Putting them onto interstellar trajectories could open up pathways to larger, more biologically complex missions depending on what they find.

I think the emphasis on biology here is heartening, for space research even in the near-term has been top-heavy in terms of propulsion engineering, obviously critical but sometimes neglectful of such critical matters as how to create closed loop life support. Even a destination as nearby as Mars forces us to ask whether humans can adapt long-term to sharply different gravity gradients, among a multitude of other questions. Thus the need for an orbital station dedicated to biology and physiology that would inform mission planning and spacecraft design.

But that kind of complex starts with humans and examines their response in nearby space. What Lubin and team are talking about is studying basic biological systems and their response to conditions outside the heliosphere, where we can begin experiments within the realm of interstellar biology. Any lifeforms we send to interstellar space will be exposed to conditions of zero-g but also hypergravity, as during the launch and propulsion phases of the flight. We would likewise be working with experiments that can be adjusted in terms of exposure to vacuum, radiation and a wide range of temperatures affecting a variety of sample microorganisms.

A Fleet of Interstellar Laboratories

How to experiment, and what to experiment on? Remember that we’re dealing with payloads of wafer size given our constraints on mass. The UCSB work has focused on the design of a microfluidics chamber that can provide suitable conditions for reviving and sustaining microorganisms on the order of 200 μm in length. The paper refers to performing ‘remote lab-on-a-chip experiments,’ using new materials, discussed within, that are enhanced for biocompatibility. I don’t want to go too deeply into the weeds on this, but here’s the gist:

[New thermoplastic elastomers] can be manufactured with diverse glass transition temperatures and either monolithically prepared with an imprinter or integrated with other candidates, such as glass. Polymerase chain reaction (PCR) on a chip is another area that will evolve naturally over the next decade and is one of many biological techniques that could be incorporated in designs. It is also possible that enzymes could be stabilized in osmolytes to perform onboard biochemical reactions. For the study of life in the interstellar environment, it is necessary to include experimental controls (in LEO and on the ground) and the use of diverse genotypes and species to characterize a wide response space…

The biological species best suited for this kind of investigation will have to have key characteristics, the first of which is a low metabolic rate in a chamber where, due to mass restrictions, nutrients will be limited. Also critical is cryptobiotic capability, meaning the ability to go into hibernation with the lowest possible metabolic rate. A tolerance for radiation is obviously helpful, making certain species clear candidates for these missions, especially tardigrades (so-called ‘water bears’), which are known for being ferociously robust under a wide range of conditions and are capable of reducing biological activity to undetectable levels.

We know that tardigrades can survive high radiation as well as high pressure environments; they have been demonstrated to be capable of enduring exposure to space in low Earth orbit. A second outstanding candidate is C. elegans, a multicellular animal small enough that a teaspoon can hold approximately 100 million juvenile worms. Also helpful is the fact that C. elegans has a rapid life cycle of about 14 days, and can, like tardigrades,be placed into suspended animation for later recovery. Other prospects among organisms and cell types are examined in these pages, and the authors call for near-term experiments on mammalian cells to delve into their response to space conditions.

Clearly, a high radiation environment, as found between the stars, offers the chance to study how life began by varying the degree of radiation shielding to which prebiotic chemicals are exposed:

The high radiation environment of interstellar space provides an interesting opportunity to study the biochemical origins of life in spacecraft with low radiation shielding versus those equipped with protective measures to limit the effect of galactic cosmic radiation (GCR) on the prebiotic chemicals, possibly shedding light on the flexibility in the conditions needed for life to arise.

Thus a spacecraft of this sort can also become an experiment in abiogenesis, the formation of nucleic acids and other biological molecules having heretofore been recreated only under laboratory conditions on Earth or in low-Earth orbit. Designing the equipment to make such experiments possible is part of the ongoing developmental work for Starlight.

An interstellar experimental biology probes the factors that make some organisms better adapted for space conditions, but it does hold implications for human expansion:

Selecting for species that are physiologically better fit for interstellar travel opens up new avenues for space research. In testing the metabolism, development, and replication of species, like C. elegans, we can see how biological systems are generally affected by space conditions. C. elegans and tardigrades are inherently more suited to space flight as opposed to humans due to factors like the extensive DNA protection mechanisms some tardigrades have for radiation exposure or the dauer larva state of arrested development C. elegans enter when faced with unfavorable growth conditions. However, as there is overlap between our species, like the human orthologs for 80% of C. elegans proteins, we can begin to make some predictions on the potential for human life in interstellar space.

Any time we ponder sending life forms into space, including simple bacteria that may have contaminated lander probes on other planets, we run into serious issues of planetary protection. I want to look at the paper’s discussion of those in the next post, along with a consideration of space-based biology in the context of concepts that could offer backup systems for Earth.

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


{ 31 comments… add one }
  • Dmitry Novoseltsev October 22, 2021, 6:46

    We remind you that our company “D-Start” is developing pulse engines for such as femto-class: file:///C:/Users/user/AppData/Local/Temp/SRIC3-SDE-2.2-02.003.pdf. Soon we will be able to offer the first samples based on spacecraft with engines of the “Impulse-A” or “Block” type as such laboratories, for launching beyond the radiation belts of the Earth and then further. It is especially important that similar organisms tolerate high overloads well with a single-pulse maneuver with a large speed increment. All interested are invited to contact: danovoseltsev@mail.ru .
    And in the future, this project is in good agreement with our project “Catalysis”

    • Andrew Palfreyman October 22, 2021, 9:01

      File sharing made easy :)

    • Alex Tolley October 22, 2021, 13:46

      I’m afraid file sharing like this does not work. You are a tech person, right? Andrew P says this far better than I with his comment. ;)

  • Antonio October 22, 2021, 10:11

    I don’t really see the point of this experiment. It seems that it could be done, to a decent approximation, in interplanetary space instead of interstellar space, and certainly it doesn’t need ships travelling at 0.2 c. If we had such ships I could imagine much better uses for them than this.

    • Alex Tolley October 22, 2021, 13:53

      I think most of it could be done on Earth without needing to go into space at all. (see my longer comment). While these experiments don’t necessarily justify building GW phased laser arrays, the point is that these experimental conditions haven’t even been thought of before. They might be very much more important for observing survival rates for a future life seeding program, although one cannot seed sterile worlds with a few organisms (no ecosystem web) and living worlds should probably be left alone and undisturbed by possible invasive organisms (or because the biology is fundamentally different and the seed organisms promptly expire). As for getting clues about human effects of spaceflight at such velocities…

    • Ron S. October 22, 2021, 14:05

      It’s worse than that. Many of these experiments have already been done in the lab, with tardigrades, bacteria and more. Stick the organisms in a vacuum chamber and bombard them the particles and radiation flux that is known to exist out there. I haven’t read the paper so I hope that there is a better justification for redoing the experiments in this fashion. Perhaps I’m being overly critical when I say that this strikes me as a solution in search of a problem.

    • Andrei October 23, 2021, 13:15

      Thank you for your post Antonio.
      And my reaction was exactly the same, that this can be done in a lab. While such miniature craft travelling at 0,2 C is unlikely to be retrieved. The result can be quite better with studied in a lab after simulation, even then I see little point for such an experiment.
      We do not know what our motivation and possible goal we might have in bioforming a world orbiting another star. But if that day arrive, I am certain the engineers and scientists who make the transport vessel will make certain the cargo is very well protected.

  • Alex Tolley October 22, 2021, 13:43

    I’m biased. but I was very enthused by this paper. The focus on biology, the miniaturized tech (lab-on-a-chip with thin film plastics is a long way from the first versions 2 decades ago that I recall. PCR analysis similarly miniaturized – the spin-off possibilities are very interesting for research and medicine).

    The choice of organisms to study is good too, especially the model organism C. elegans. The only addition I would make is possibly zebra fish eggs/embryos.

    What I am not so sure about is the science that can be achieved. Looking at effects as one thing, but what do they tell us? It is somewhat disconcerting to read that multiple variables are good, when this is teh very antithesis of doing controlled experiments. As all the organisms experience hyper-gravity first, who is to say how much of the effect is due to this alone, and certainly influencing other effects.

    Lastly, apart from the relativistic GCRs grazing or hitting the organisms during flight, which of the experiments could be done better on Earth, using ultra centrifuges, vacuum, desiccation, particle impacts from an accelerator, etc., etc.?

    But overall, I love the aim to achieve the extreme miniaturization. Even if they achieve that but don’t get to fly such a mission, the results may well be worth it.

  • ljk October 22, 2021, 14:35

    The Lifetime of Spacecraft at the Solar Gravitational Lens

    This is a guest post by Stephen Kerby, a graduate student at Penn State.

    Imagine you are a galaxy-spanning species, and you need to transmit information from one star to another. You can just point your radio dish at the other star, but space is big, and your transmission is weak by the time it reaches its destination. What if you could use the gravitational lensing of a nearby star to focus your transmission into a tight beam while monitoring local probes? What if you could use this nice yellow star right here, the locals call it the Sun? What if the locals notice your transmitting spacecraft from their planet right next to the star?

    Recently, there has been renewed interest among human scientists in using the solar gravitational lens (SGL) to focus light for telescopic observations (as in the FOCAL mission) or for interstellar communication (as described in Maccone 2011). A spacecraft positioned >500 AU from the Sun could collect focused light bent by the Sun’s gravitational field, dramatically increasing the magnification of a telescope or the gain of a transmitter for a point on the exact opposite side of the Sun (the antipode). The picture below shows how the SGL could be used for transmission of an interstellar signal, and the arrangement can be reversed to focus light onto a telescope.

    Full article here:


    • Antonio October 22, 2021, 15:54

      Mmm the article doesn’t seem to address the first point that came to my mind before reading it: could such a spacecraft be really detected from Earth?

      A giant planet at roughly the same distance, like Planet Nine, is on the limit of detectability for our best optical telescopes. How much power does such a small spacecraft need to transmit to be detectable in radiowaves?

      • Mike Serfas October 23, 2021, 10:02

        For purposes of brainstorming it sometimes pays to look at Wikipedia, and this time someone there delivered: https://arxiv.org/ftp/arxiv/papers/2005/2005.08940.pdf This is the Breakthrough Starshot systems director arguing he can get 288 photons from Alpha Centauri to a 30-meter telescope on Earth. He has 700 Watts for the transmitter from a “hydrogen beam” (interstellar medium) hitting the main reflector used at launch. Now how he expects to aim that thing at a telescope on Earth … I don’t understand how he did the decibel calculation, and he does suggest a very severe attenuation, so maybe it doesn’t have to be that precise? I don’t yet understand if the probes have to have an interstellar medium battered reflector that is somewhere between Hubble and JWST in terms of imaging quality, when every solar sail I’ve heard of comes out looking more like a craft project with aluminum foil.

    • Jeff Wright October 22, 2021, 21:51

      Just this past week’s phys.org stories has articles on fresnel like membrane lenses-and last week tiny craft were pushed about by the pressure of light. I wonder if these organisms can be gene wired to become other things at destination…

  • Alex Tolley October 22, 2021, 15:58

    What if the locals notice your transmitting spacecraft from their planet right next to the star?

    The minimum surface area to search for the probe in the dark is 4*pi*r^2, where r = 550 AU => 8.55E22 sq km. That is a large area to search, or 1.7E14 x the area of Earth. Now add in the gravitational focus is a line extending towards infinity, the volume to search is even larger.

    I am sure that in one reason the Benfords don’t suggest looking for “lurkers” in the outer dark. One would really want to have identified an extra solar target system to drastically lower the area/volume to search for a probe.

    • Eniac October 23, 2021, 11:51

      To be efficient, a gravitational focus communicator would aim their signal at the Einstein ring around the sun. Thus, if the position is known, it is easy to compute where to position a detector to maximize the probability of detecting such a signal. If we are looking for a galactic communication network, the most likely connections are to nearby stars, which gives us a fairly short list of positions to check out. I think this could be a worthwhile project. It would require a sensitive radio-telescope to be sent on a trajectory through the inner solar system that intercepts as many of the hypothesized signals as possible. Not the most expensive mission, ever.

  • Geoffrey Hillend October 22, 2021, 16:12

    I think it is important that we know how well microorganisms, bacteria, viruses, can survive in space. We have to be careful though that the seeding of space does not become the seeding of another planet which might be harmful for it’s indigenous life and is unethical.

    The same problems for long distance interplanetary travel as for interstellar travel for humans; the loss of bone mass and muscle for long term exposure to the zero gravity environment of deep space. Artificial gravity has to be made by spinning the spacecraft unless we figure out how to make a gravity control device which emits gravity waves.

    Ljk, gravitational microlensing won’t work for radio transmissions since they are not as nearly as bright as stars which is why we can see them gravitationally lens for lightyears. One can’t make a telescope out of that lensing.

  • Steve McDaniel October 23, 2021, 8:05

    I agree that these same experiments can be generally accomplished without establishing an “interstellar lab,” per se. But, there is much to be learned in such far-flung experimental locations that may not directly relate to the core experimental purpose (i.e. how to prevent planet-bound spacecraft from forward and backward contamination). Our company has been keenly aware of the potential for forward and backward contamination on spacecraft surfaces for some time. We address the problems (yes, it’s not just microbes but also their nucleic acids with which we must contend) using bio-based functional coatings.

  • Michael Fidler October 23, 2021, 10:07

    A new type of EM Drive that corrects the problems of the microwave and piezoelectric EM drives.

    EM propulsion drive

    Larry Reed
    2020, Quantum Wave Mechanics
    81 Pages

    EM propulsion drive technology road map. Matter in motion exhibits internal Lorentz-contracted moving standing waves (de Broglie matter waves). The inverse effect of self-induced motion of matter may be potentially realized by utilizing synthesized red- and blue-shifted Lorentz-Doppler waves in a phase conjugate four-wave mixing process modulating a standing wave signal to generate a matter wave producing self-induced motion of a wave system without expulsion of reaction mass. A simplified impulse drive may be constructed with a standing wave cavity resonator excited by two-counter-propagating traveling waves with independent phase and frequency control.


    • Alex Tolley October 23, 2021, 12:17

      That is one large document, full of bafflegab, flying saucers, and…no indication that violates known physics.

      As a retired aerospace engineer, it really shouldn’t be that hard for him to pull together the finance from a few friends, build the device, and show that it actually works. It might even be easier that compiling the document. Mr. Reed looks rather young to be “retired” and seems to passed his retirement publishing many new physics ideas. The only thing this has done is further reduce my interest in Academia.edu as a site that has pushed a number of suspect documents into my email polluting the better papers that occasionally emerge.

      No “reactionless drive” has even been shown to unambiguously work. [ I even had a friend who deluded himself into thinking his version worked despite all the evidence it did not and their resistance to doing a proper experiment. ] It wasn’t that long ago that there were attempts to explain some “new physics” that might be in operation to make the EM Drive work. In due course the idea died.

      Marc Millis has done some excellent work testing space drives and I recommend [re]reading his post on CD ( Marc Millis: Testing Possible Spacedrives.

      • Michael Fidler October 24, 2021, 3:15

        Response from Larry Reed, Alex on your comments;

        Thanks again for the Messen papers. They are very interesting, however, rather terse and sketchy.

        Lorentz Doppler shift, de Broglie matter waves, travelling waves, standing waves, inverse Doppler effect, electromagnetics, gravitomagnetics, coupled oscillator interaction, vector potential, phase conjugation, etc are well-established known physics not bafflegab as Mr. Tolley asserts.

        Russian scientists at Neila-Tech under direction of Dr. Y. N. Ivanov have already experimentally demonstrated propulsion using moving standing waves. R.C. Jennison et al have previously experimentally demonstrated self-referral dynamics of standing wave radiation trapped in phase-locked cavity resonators in motion using microwaves and lasers. As previously noted, Shawyer made a good start, but unfortunately, relied on single-frequency excitation of a resonant cavity in an attempt to induce motion. This only results in standing waves with fixed nodal endpoint regardless of the resonant Q-factor. Motion of matter requires dissonance at resonator endplates which results from radiation pressure imbalance due to interference of red- and blue-shifted counter-propagating travelling waves. At lease two sources of excitation are required of disparate frequency. Dissonance corresponds to Fibonacci ratios while consonance corresponds to Pythagorean ratios. Resonator velocity is proportional to phase difference while acceleration is proportional to frequency difference. Resonator motion involves push-pull dynamics, a fundamental property of trapped radiation within a cavity resonator which explains the underlying basis for Newton’s 2nd law of motion.

        Alex, you may learn something if you read his book “Quantum Wave Mechanics” – Third Edition with 724 pages including references and a good index. The great astronomer R.C. Jennison is the key…

      • Robert October 25, 2021, 13:25

        Woodward and Fearn are now getting some recent results that seem a bit less ambiguous and stronger that earlier results. Time will tell.

        • Michael Fidler October 26, 2021, 21:26



          Experiments were carried out with a boat that moved in a pool due to the phase shift of interfering waves emitted from two piezo emitters installed on the hull of the boat. For this experiment, a plastic boat was utilized, on the bottom of which two counter-directed piezoelectric emitters were placed.

          On the upper part of the hull, a two-channel signal generator was placed, which generated signals for the piezoelectric emitters. After that, the boat was placed in the water and both piezo emitters were given signals which were in phase and with the same frequency.

          As a result of interference between the emitters, standing waves were created. If the emitters worked in phase, the boat maintained a state of rest on the water. But if the generator created a small phase shift of several degrees, the boat began to move on the water surface.



          • Alex Tolley October 27, 2021, 10:28

            Unless you believe that space contains an Ether to react against, this boat experiment has no relevance to reactionless space drives.

            • Paul Gilster October 27, 2021, 10:38

              In any case, let’s get back to topic, which is biological experimentation in deep space, as enabled by a particular class of mission. If we start pulling up all the reactionless drives out there, we’ll wander far from Project Starlight.

  • Neil October 23, 2021, 15:33

    We need to think hard about scattering objects traveling at 0.2c around the neighborhood. Maybe they would be guaranteed to slow down to sub-relativistic speeds soon due to friction effects but if a few thousand little objects traveling at relativistic speeds came through the solar system, some hitting Earth, one possibly taking out a space mission (unlikely but possible) or a multi-billion dollar space telescope, or just being somehow detected as they approach and smash into a planet or so, I think we would take it as an aggressive act or at a minimum an irresponsible act. That’s no way to introduce ourselves.

  • Geoffrey Hillend October 23, 2021, 16:15

    I agree with Alex Tolley about the reactionless drive which needs a space warp and negative energy to work. We don’t know how to make negative energy or even the positive energy of a gravity control device. Until we do, there won’t be any reactionless drives. EMR alone can’t make a space warp.

    • Robert October 26, 2021, 14:41

      Physicists Jack Sarfatti and Keith Wanser believe warp effects can be achieved with meta-materials and do not require exotic forms of negative energy. It would be nice if that were to be confirmed.

  • Robin Datta October 24, 2021, 1:49

    Sort of like mounting the experiment on an Indy 500 racer or a Kentucky Derby thoroughbred.

    If we’re looking at/for biology, there is plenty in biology itself. Even among humans, adaptive changes are noted: bigger lungs and erythron (total red blood cell mass) among the residents of the Himalayas/Tibet and the Andes. That took 5+ millennia of natural selection in a rarefied atmosphere. A bit long if one considers modifying humans for other environments “quickly”, and a bit harsh if strict adherence to natural selection is implied: we’re here because our direct ancestors didn’t become dinner for their then-contemporary predators.

    Sending our microfauna for a ride or to seed other worlds involves way too many variables (known unknowns & unknown unknowns): the results may have educational value whether or not within the realm of our expectations. But some may contend that experiments could be better designed.

    Looking for variant DNA subunits and molecular chiralities could be revealing, but we have to lay our “hands” on the stuff first. Similar stuff may already be here in meteorites or deep in fissures in the earth’s crust.

    Gathering data from elsewere could be focused on such aspects as biosignatures and astro-archeology. Until we are in possession of representative samples.

  • Gregory Benford October 24, 2021, 14:47

    The “n laboratory experiments at JPL,” should include the experiments we did at UCI on stabilizing cone-shaped sails under microwave pressure, too–NASA funded.

    • Jeff Wright October 26, 2021, 5:00

      Cone shapes would be less limber-less prone to flap. If the nose has a hole, maybe a brake vent?

  • Joe H. October 30, 2021, 11:49

    “You could put something of human manufacture into the Alpha Centauri triple star system within about 20 years.” This is a big half-truth. The light sail wouldn’t STAY in the Alpha Centauri system more that a few days without some way to slow down.

    • Mike Serfas October 31, 2021, 9:38

      Why did they use the phrase “triple star system”? Because Proxima Centauri is 0.2 light-years away from the other two! So the probe, moving something under than 0.2 c apparently, should be in the “triple star system” for about a year. :) No, that doesn’t mean we can expect close-up pictures, but someone can issue a NFT for every day of presence of a human artifact in the alien star system. It could be worth a fortune! :)

      Apparently there *is* a plan: pulling 14 soccer fields’ worth of solar sail out of the Starshot probe. ( https://www.sciencealert.com/scientists-have-figured-out-how-to-actually-stop-an-interstellar-spacecraft ) If a performance artist would do this at a theater, it would be very impressive.

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