Interstellar Probe: The 1 KG Mission

by Paul Gilster on March 31, 2014

Reading Charles Adler’s Wizards, Aliens and Starships over the weekend, I’ve been thinking about starflight and cost. Subtitled ‘Physics and Math in Fantasy and Science Fiction,’ Adler’s book uses the genres as a way into sound science, and his chapters contain numerous references to writers like Poul Anderson, Larry Niven and Robert Heinlein. On the matter of speculative propulsion systems, he lingers over fusion and describes the work of Project Daedalus back in the 1970s, when an ad hoc team of volunteer scientists and engineers put together a serious starship study.

Like the vessels written about in the science fiction of that era and before, Daedalus was simply a mammoth craft — 53 million kilograms! — but that corresponded with what SF had been telling us all along. We would travel to the stars aboard vessels not so different from ocean liners, perhaps big enough to be livable on a daily basis, or at least big enough to pack thousands of humans into cryogenic containers for a trip under suspended animation. It’s a natural enough thought: Long journeys demand big vessels. Scenarios like this burn up plenty of energy, as Adler is quick to note:

…the implication of an interstellar probe [like Daedalus]…is that we possess an extremely energy-rich society. The cost of Project Daedalus was estimated at $10 trillion. Using the rule of thumb that prices for everything double every 20 years, the estimate comes in at about $40 trillion today, dwarfing the U.S. GDP. This amount of money is about equal to the GDP of the entire world. Energetics tell us why this is so: the total energy contained in the payload is about 10% of the total world energy usage for one year. This is too expensive for any current world civilization to undertake, and it may well be too expensive for any civilization to undertake under any circumstances.

Adler, a professor of physics at St. Mary’s College in Maryland, is a lively writer who is well versed in both science fiction and fantasy, making this an entertaining volume indeed. He doesn’t mention the ongoing Project Icarus study, but it will be interesting to see how the ensuing years have modified the original Daedalus concept to produce a less costly, more viable design. Even so, the assumption is that a fusion starship as designed today is going to be a large vehicle because it has to deliver enough of a payload to make the journey to the star worthwhile.

Realm of the Small

Enter Alan Mole. A retired engineer, Mole is an aerospace stress analyst who has worked at the University of Colorado Laboratory for Atmospheric and Space Physics, and as a contract engineer for Ball Aerospace, McDonnell Douglas, Pratt and Whitney, Thiokol-ATK and other firms. A recent issue of the Journal of the British Interplanetary Society contains his paper “One Kilogram Interstellar Colony Mission,” which reverses the big starship paradigm and looks to deliver a seriously effective payload at a sharply reduced cost. Mole is, he tells me, interested not only in physically possible ways to solve difficult problems, but also in making the solutions economically feasible.

scenicmilkyway3_hepburn

Image: The Milky Way over Ontario. As we ponder a human future in the stars, can nanotech and biology breakthroughs show the way forward? Credit & Copyright: Kerry-Ann Lecky Hepburn.

The difficulty of the problem is hard to overstate. It was not some skeptical bystander but Anthony Martin himself, a major player in the Daedalus design effort, who noted the cost to the society that chose to build Daedalus: “It seems probable that a Solar System wide culture making use of all of its resources would easily be wealthy enough to afford such an undertaking.” But Alan Mole is not the first to point out that we are developing lower cost alternatives. If we can create a smaller payload and find a propulsion method that scales down to meet its requirements, we can start talking about an interstellar effort that would prove economically viable while offering choices for human expansion including interstellar colonization.

If Daedalus totalled 53 million kilograms, Mole thinks we should be looking at a single kilogram as sufficient for our colony probe. Making something like this even imaginable involves advances in artificial intelligence, computer memory, materials science, nanotechnology and biology that we can imagine continuing throughout the century, barring the kind of societal catastrophe that disrupts civilization itself. The kind of probe Mole envisions is a world in itself or, I should say, the seed of a world to come, for it uses technology to raise a human colony at destination:

Consider a one kg colony probe sent to a nearby extrasolar planet at about 0.1 c. It will land and nanobots will emerge to build ever larger robots and greenhouses etc. for colony infrastructure. The nanobots will be powered by batteries and recharged by solar cells, building larger arrays of these as work progresses. They will then hatch human embryos (millions per gram) or build humans directly from DNA formulas stored in memory (as was done for a simple bacterium in the artificial life experiments in 2010.) The probe will transmit no data to Earth but if the colony is successful it will eventually build transmitters and establish contact.

Charles Adler doesn’t suggest science fictional treatments of such ideas, but I know current authors must be working this turf, and I’d appreciate pointers from readers. I’m reminded of Robert Freitas’ ideas about self-reproducing probes, a concept I discussed in Centauri Dreams (the book) in the context of an earlier Freitas idea called REPRO, which involved probes on a Daedalus scale that built replicas of themselves and continued out into the galaxy. By reducing the probe to the size of a sewing needle, Freitas envisions sending just enough nanotechnology to turn assemblers loose at destination to build a station to take scientific measurements, report findings back to Earth and, eventually, move on to another star.

Alan Mole is likewise intrigued by the world of the small, but as the above quote demonstrates, he’s thinking in terms of biology as well. Tomorrow I want to explore the implications of Mole’s thinking, looking first at previous ideas for very small payloads from the likes of Freeman Dyson, Dan Goldin and Gregory Matloff. Then we’ll talk about the propulsion systems that could make such a concept work. For it may not be feasible to carry our propellant with us, opening the door for a variety of beamed energy concepts whose cost is far less onerous than the alternatives.

The paper we’ll be discussing for the next few days is Mole, “One Kilogram Interstellar Colony Mission, Journal of the British Interplanetary Society Vol. 66, No. 12, 381-387.

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Charlie Stross March 31, 2014 at 11:35

They will then hatch human embryos (millions per gram) or build humans directly from DNA formulas stored in memory (as was done for a simple bacterium in the artificial life experiments in 2010.)

I don’t buy this. (It’s a classic instance of the “and now a miracle happens” problem.)

Sure, it should be feasible to ship fertilized ova across interstellar distances, fix damage incurred en route or select viable survivors. But the “simple” job of incubating them to term is anything but simple. A uterus isn’t just a passive vessel that supplies oxygen and nutrients and warmth: there are a host of immunological and epigenetic interactions between mother and child that take place across the placental barrier and determine developmental processes in the embryo. And once you get to delivery the problems exponentiate. Human babies are developmentally plastic; they don’t come pre-programmed with any particular language or skill set. The big ask here is “give me a magic machine that can raise, educate, and socialize human beings”, and the solution would have to be either (a) a human being, or (b) an AI that is foster-parent-equivalent, i.e. human grade. At which point we’re veering wildly off the road into Vingean AI singularity territory. Why bother sending human seeds at all when we can just send a simpler and better-understood AI ecosystem, programmed to build laser or radio receivers and download our upgrade instructions in due course? Especially as humans are not exactly optimized for survival without extreme life support measures anywhere except about 20% of our own planet’s current surface …

CharlesJQuarra March 31, 2014 at 12:29

Needless to say, fusion rockets are a sexy concept, but they are still ruled by the oppressive dictatorship of Tsiolkovsky equation. So at best, their energy efficiency never gets above the single digit percent. But regardless of how we eventually will ‘get there’, the idea of sending the assembly line to build the payload, instead of just sending the payload, is a sound one. If the actual payload is vastly diminished, then having energy-efficient propulsion is not that important, compared to having a propulsion device that is cheaper to build and to launch

Alex Tolley March 31, 2014 at 14:14

They will then hatch human embryos (millions per gram) or build humans directly from DNA formulas stored in memory (as was done for a simple bacterium in the artificial life experiments in 2010.)

Obviously a lot of hand waving here. Creating a human requires more than DNA – a cell to transplant the DNA to, a womb to gestate the embryo, a social system to educate the child until adulthood, etc, etc. Not impossible, but this all has to be prepared from the [nanotech] ground up.

I think the general idea is a good one, but I suspect that it will work best without humans and stopping at macro robots (or even micro ones). For long range civs, just engineering microbial life for local conditions and letting evolution take its course might be the way to go.

Leon March 31, 2014 at 14:53

I think that the way to start is with a small probe to scout out and find potential targets for later, larger probes or possibly manned missions. A small probe of 500 kg or less would be far easier to get up to speed than a multi million kg payload. However, even if we had a propulsion system that could get a small probe up to 1/10 light speed, there are several MAJOR problems to overcome during the journey.

Problem one is that if a fleck of dust weighing just 1 gram were to hit the probe at that speed it would probably turn the probe into a growing ball of shrapnel headed towards the destination star system or at least render it inoperable. This means that a detection, clearing and/or deflection system(s) would be required if the probe were to have any chance of actually arriving in one piece.

Problem 2 is that of communications. Do we have the technology to send data from a planetary system over 4 light years away?

Problem 3 is that even if we have the communications system in place (see problem 2 above) it will likely be a one way process from the destination star system to Earth because of the round trip times involved. This means that the probe will have to have the intelligence to decide on where and what the targets are for exploration. It will have to decide how long to observe a given target and when to move on. It would be a shame for the probe to be sending pictures back from a planet that actually has rudementary intelligent life and then after a year move on to the next target, rather than continuing to study that intelligent life. Transmitting a signal from Earth to the probe to continue the study wouldn’t work because of the round trip time of the signal.

Keep in mind that is IF we actually had a propulsion system that could get a probe up to 1/10 c, which, unfortunatly, we don’t.

I seldom see any information or studies on how to overcome the problems I have listed above. Perhaps Centauri Dreams could do a write up on what is being studied to over come these problems.

Paul Gilster March 31, 2014 at 16:48

Leon writes:

I seldom see any information or studies on how to overcome the problems I have listed above. Perhaps Centauri Dreams could do a write up on what is being studied to over come these problems.

Leon, you’ll want to check into the archives here, as these are issues we discuss frequently. The communications issue, for example, gets us into a variety of articles about interstellar communications solutions from JPL’s James Lesh to more recent work from David Messerschmitt and others. The propulsion concepts rotate through frequently, so try searching under various keywords. Here are pointers to specific articles as starters, but the archives hold more under each topic:

On dust and collisions: http://www.centauri-dreams.org/?p=22515

On communications with an interstellar probe: http://www.centauri-dreams.org/?p=26219

On propulsion there are numerous options. Here’s one piece on beamed sails: http://www.centauri-dreams.org/?p=20962

And one on Bussard ramjets: http://www.centauri-dreams.org/?p=22274

Anyway, check the archives for the backlog. We’re up to close to 3000 posts now over the past ten years, and issues like these are a major component of what this site is all about.

Gerry March 31, 2014 at 19:55

tl;dr : When it comes to micro-starships with molecular assemblers for colonization, if you are advanced enough to send embryos to ‘hatch’ and raise, just send ‘uploaded’ minds instead.

When it comes to growing biological human colonists from embryos, I think there are both practical and ethical questions to consider. These might overlap somewhat with the questions that are raised by the notion of generation ships. Do we have the right to consign future generations to carrying out a colonization project chosen by us, on their behalf? A lifetime possibly confined to a starship or, in this case, a life-supporting habitat in a hostile alien environment? If it’s a question of avoiding human extinction, then perhaps the answer would be yes. But lacking such a clear imperative, a careful weighing of the issues is warranted.

Also, we know from psychological research that a child’s environment and upbringing, the formation of healthy social bonds and emotional attachments, are important foundations of adult functioning. Even if artificial wombs were possible, would there be a crew of AI android parents (presumably constructed from nanotech assemblers) on hand to help raise and socialize these kids? To cuddle them as babies? Remember the difficulties faces by the Romanian orphans in the 1990′s.

Ultimately, if you have the capability of creating a seed which can produce android parents and the rest of the complex infrastructure to raise humans from embryos to adults, why not just send a host of human-based minds (so-called “uploads”) on the tiny ship, and let them grow whatever kinds of bioborg/cyborg bodies the target world and their whims dictate, and forget about the embryos altogether?

That would make for a cool sci-fi setting; a tiny computronium spaceship crewed by uploads who, for reasons of nostalgia and entertainment, inhabit a virtual environment made up to resemble an Enterprise-like ship, with clean shiny halls, and sexy uniforms in bright primary colors…

James Benford March 31, 2014 at 20:40

Most of interstellar propulsion thinking is oriented toward rockets: huge expendable rocket, small payload. But the one-vehicle approach to exploring a new planetary system results in an enormous payload, such as the 150 ton Icarus payload spec. (I’ve always thought it was strange idea that starship had to have a payload that was 415 times that of the entire mass of Voyager 2.)

This highlights one of the key advantages of sailships: they and their payloads can have small mass. That’s because many such sailships can be sent, sub-divided into payloads of much lower mass than the all-eggs-in-one-basket rocket (so the project degrades gracefully if we lose this month’s sailship). That’s because the cost per ship is very small compared to rockets, the major cost having been left behind: the Beamer. It’s back in the solar system, could launch as often as perhaps once a week, or whatever the assembly and deployment time is for sailships.

For comparison, look at the key parameters of the two Icarus designs from the October meeting, a US supercarrier and a sailship:

Firefly 0.7 km, 19,000 tons, 40 T$, 4.6%c, magsail mass 1/300
Ghost 1km, 154,000 tons, 0.02-34 T$, 6%c
Carrier 0.3 km, 105,000 tons, 0.01 T$
Sailship 10 km, 10 tons, 40 T$, 10%c [cost of electricity to drive the beamer at today’s rate (0.1 $/kw-hr) is 0.5 T$.]

With the Rocket approach the infrastructure, necessary to build such huge vessels and supply nuclear fuel, is thought of as a fixed cost, but is not estimated in these designs, but should be. The final stage the only part of the rocket that actually reaches the objective. It’s perhaps better to think of most of the rocket itself as infrastructure cost. Then that infrastructure cost of rockets is actually quite huge. That’s because the rocket is expendable: almost all of the expensive system is discarded to get the payload into the new stellar system.

Sailships, in contrast, have a quantifiable infrastructure cost in the Beamer, and the entire sail, minus its decelerating magsail, arrives in the new stellar system. In this sort of comparison, the rocket “infrastructure” is actually quite large and so sailships may in fact be substantially cheaper per payload.

From the nearer-term point of view, it’s cheaper for civilization to build sailships infrastructure and then launch many probes from it. From the longer point view, the continuing high cost of constantly-replaced rockets will make sailships seem even more economical once there are being sent in large numbers, exploring several nearby solar systems.

Leon March 31, 2014 at 23:14

Thanks for the response Paul. Much appreciated.

I am fairly well versed on the propulsion ideas to date. Some of the stuff on communications I had read but it had slipped my mind. The stuff on space dust I had not read but found that I had some of the same ideas for detecting and clearing the path ahead of the probe.

Thanks again,
Leon

Alan Mole March 31, 2014 at 23:26

Mr. Stross writes:
____________________
I don’t buy this. (It’s a classic instance of the “and now a miracle happens” problem.)

Sure, it should be feasible to ship fertilized ova across interstellar distances, fix damage incurred en route or select viable survivors. But the “simple” job of incubating them to term is anything but simple. A uterus isn’t just a passive vessel that supplies oxygen and nutrients and warmth: there are a host of immunological and epigenetic interactions between mother and child that take place across the placental barrier and determine developmental processes in the embryo. And once you get to delivery the problems exponentiate. Human babies are developmentally plastic; they don’t come pre-programmed with any particular language or skill set. The big ask here is “give me a magic machine that can raise, educate, and socialize human beings”, and the solution would have to be either (a) a human being, or (b) an AI that is foster-parent-equivalent, i.e. human grade. At which point we’re veering wildly off the road into Vingean AI singularity territory. Why bother sending human seeds at all when we can just send a simpler and better-understood AI ecosystem, programmed to build laser or radio receivers and download our upgrade instructions in due course?
_________________________

I cover some of this in the paper. Goat embryos have been grown to birth — almost.

“3.There has been progress in growing an embryo into a baby. In 1989 Japanese scientists incubated a goat fetus in an artificial womb for many days and it grew to birth size. It did not come to life and breathe on its own but the technology seems to have been close to success.[8] If direct construction does not work this may be an alternative.

Regarding the ethics of sending embryos into danger, today in-vitro fertilization for fertility treatments creates millions of human embryos each year, most of which are frozen and eventually destroyed. If instead some parents donate their embryos to the project, those embryos will have at least some chance at life. Opinions will vary over whether this is ethical but since the present practice is allowed so should this be.”

I would indeed use human minds in android bodies to raise the children. You are right that the androids would be almost as good as humans in the flesh. In cases where only asteroids or airless bodies orbited the particular star, we might stop with androids, which would be better suited in such a case.

Andrew Palfreyman April 1, 2014 at 0:35

Especially if the destination is Alpha Centauri, it would be a good idea to get those assemblers busy building a beamer in situ, because there are two more stars relatively close by that could conveniently explored. Alternatively, a late course correction for two thirds of the lightsail swarm so we get three birds with one stone

Antonio April 1, 2014 at 6:25

I think this is a very bad idea:

(1) Mission is too slow. Apart from travel time, we have to wait until an entire civilization and biosphere develops in the target planet before we have the first data about it!

(2) We can’t decide if we will colonize the target world, since we have no data. A single computer must find out wether the planet hosts life or not (something we never did before and barely have any idea how to do) and make such important decision as to whether colonize or not.

coacervate April 1, 2014 at 6:59

3D print a larval bionaut on arrival. There is a lot of ice there. Tailor the larvae to withstand harsh conditions(water bear motif?), find a mineral rich comet, harvest raw materials. Grow, store a larder and then trigger metamorphosis to viable maturity. Think like photosynthetic wasps. but don’t upset the neighborhood.

swage April 1, 2014 at 9:47

Wonderful.

“I don’t buy this.”

Well, blatantly put it is possible and i mean guaranteed possible, because we know – at least for all we know at this time – all biology on Earth arose from the Last Universal Common Ancestor. So strictly speaking we have direct evidence that such “technology” exists and is possible, even if we are not able to reproduce it at this time. This is a fact and there is no way around it: such an approach is IS possible, it MUST be or we wouldn’t exist which we evidently do.

“the “simple” job of incubating them to term is anything but simple”

Certainly, but evidently not impossible because it already happened from a certain point of view. All we see here on this planet is within the potential capabilities of this one, little microorganism, right? Yes, it takes time, for all we know billions of years and yes it is complex but it MUST be feasible.

“The big ask here is “give me a magic machine that can raise, educate, and socialize (…)”

You have to have thrust in their capabilities to figure that out for themselves. Maybe they would do better than we did ourselves.

“Why bother sending human seeds at all when we can just send a simpler and better-understood AI ecosystem (…)”

Indeed.

“(…) humans are not exactly optimized for survival without extreme life support measures anywhere except about 20% of our own planet’s current surface (…) ”

Exactly. Complex biogenic systems must evolve from the ground up for their environment. There will be different solutions for different environments, but evolution is pretty good at figuring out what works best completely on its own. Technically you don’t even need a computer.

“If the actual payload is vastly diminished, then having energy-efficient propulsion is not that important (…)”

It may be possible to totally omit a propulsion system if the microbes ca be kept viable long enough which basically comes down to radiation shielding. Regarding the viability there are numerous reports of microbes having been reanimated after staying dormant for millions of years. There is no need for high speed, but there is a need for quantity to ensure arrival of at least a few viable specimens.

“Not impossible, but this all has to be prepared from the [nanotech] ground up. ”

I don’t think so. You cant take into account all possible circumstances. You need an adaptive system to begin with.

“the way to start is with a small probe to scout out and find potential targets for later, larger probes or possibly manned missions”

I think we can do that very well via spectroscopy without sending any probes (barring manned missions) at all. Actually we just need to do the targeting.

“if a fleck of dust weighing just 1 gram were to hit the probe at that speed it would probably turn the probe into a growing ball of shrapnel headed towards the destination star system or at least render it inoperable”

We just need to send more seeds. A percentage should have a decent chance to reach the target, increasingly so if the quantity of seeds is upped. This also would account for targeting inaccuracy.

“a detection, clearing and/or deflection system(s) would be required if the probe were to have any chance of actually arriving in one piece”

Too complex. It just increases the seed payload.

“Problem 2 is that of communications. Do we have the technology to send data from a planetary system over 4 light years away?”

Strictly taken, communication is not a necessity. But yes, we do have the technology to send data over 4 Ly and there is a chance they will, too after a couple of billion years evolutionary development. But is that really of primary importance?

“it will likely be a one way process from the destination star system to Earth because of the round trip times involved”

Probably, which further raises the question if this is a necessity.

“the probe will have to have the intelligence to decide on where and what the targets are for exploration”

Even microorganisms do explore their environment. Its quasi a built in property of life.

“It would be a shame for the probe to be sending pictures back from a planet that actually has rudimentary intelligent life and then after a year move on to the next target, rather than continuing to study that intelligent life.”

Once established it WILL stay as long as environmental conditions permit it and most likely also start sending signals – as we do – but there is a good chance it will also expand to other planets, because that is within its capabilities, as well. So both, really. No need to worry. But it will take a long time, so that is probably a moot point unless we can speed up the development process. But intuitively i feel there will be risks and tradeoffs involved in that, too.

“just send ‘uploaded’ minds instead”

That is certainly a possibility but there are ethical problems involved, as well as information preservation questions. You don’t want to impose corrupted ancient mind programming on a blooming start up civilization, would you? Perhaps a less invasive, fragmentary approach could be justified to give a little hint here and there.

“Do we have the right to consign future generations to carrying out a colonization project chosen by us, on their behalf?”

As means for ensuring the continued presence of life in the galaxy i would gravitate towards a “Yes”, but not without thoroughly studying the involved process and give them the best possible chance of success. Sending microbes is one thing (they are pretty good at confining themselves here on Earth), sending humans a totally different league (perhaps in a very huge habitat – but that is for various reasons highly impractical).

“If it’s a question of avoiding human extinction, then perhaps the answer would be yes.”

In the long run it certainly is.

“To cuddle them as babies?”

They certainly need parents. An evolutionary approach takes care of this problem, too.

Michael April 1, 2014 at 12:44

@Andrew Palfreyman April 1, 2014 at 0:35

‘Alternatively, a late course correction for two thirds of the lightsail swarm so we get three birds with one stone’

An early course correction will be needed as the power beam gets dimmer the further you get away. Splitting a sail after the acceleration phase so one goes to Proxima and the other to Alpha Centauri makes sense.

Notsoreal April 1, 2014 at 16:28

I have seen a few stories that deal with the subject. Unfortunately I cannot remember. Maybe a story as part of an anthology from Pournelle or Card? From 80s or 90s so may be a little dated. If I can track it down I will post an update.

Notsoreal April 1, 2014 at 16:43

Of course 5 minutes after I post.
See examples in Fiction Section.
http://en.m.wikipedia.org/wiki/Embryo_space_colonization

The one I was trying to remember was James P Hogan’s Voyage From Yesteryear.

Skotch Vail April 6, 2014 at 22:09

This talk of AI’s that can raise children leaves me just a bit perplexed. Bringing the smarts and seed equipment to build humans has to be a significant cost on the total mission, so there must be some value to bringing that extra baggage.

If the AI’s can raise children, teach them complex skills, make them emotionally secure and loved, establish strong cultural traditions, extensively modify an environment, build other generations of AI’s, and build all of the needed infrastructure, then why raise the children at all? Why not just raise dogs or dolphins or nothing instead?

I am trying to think of a single thing that humans could bring that is special and unique in comparison to AI’s that can do all of that. What quality would we have that would make us worth the cost / benefit analysis?

They sound like they would be more humane than humans. Honestly, if the AI is that capable, they are probably better off without our flaws impeding their project of spreading culture and intelligence across the cosmos.

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