The question of when to launch an interstellar mission has occupied us many times in the past. Specifically, how long do we wait so that travel times are reduced to something like the lifetime of a researcher working on the project? But there is another approach to all this. Someone is going to launch an interstellar mission that will be the first human effort to send a payload to another star. It’s all about intentionality and the choice of targets.
A symbolic act? Sure, but don’t write the idea off. We can learn a lot from symbolic acts, and if we only have, at our current level of technology, the ability to reach Voyager-like speeds, we can still work on issues like equipment lifetimes, self-healing technologies, navigational issues and more. We can also work to refine existing AI tools to achieve the most efficient design.
If we give ourselves 80,000 years to reach Alpha Centauri, we have to contend with the fact that the system is constantly moving. On this timeframe, by the time the craft would arrive, Centauri A and B would be a bit over 6 light years from the Sun as opposed to their current 4.365 light years. Trajectory analysis going this far into the future is going to be an interesting challenge.
I mention all this because a call to mount such a mission has now arisen. It bears the name Fermi Explorer, and according to its new website, its intention is to get a spacecraft with a 1 kilogram, 10X10X10 cm payload to the barycenter of the binary Centauri A and B system. In other words, the target is not either star itself but the common center of mass between the two as they orbit.
Some particulars: The mission should launch before the end of 2029 if the effort succeeds, and is intended to cost less than $15 million to design, build, launch and operate. Mission co-founder Philip Johnston is going to have his hands full.
As to departure, Fermi Explorer would take a year and a half moving out of Earth orbit. Then, using a series of Oberth maneuvers taking it to within 0.42 AU of the Sun, the craft would rely upon what the site calls a ‘perihelion pump,’, which involves multiple close solar flybys over 12 years to build the energy to achieve an escape trajectory that, after climbing out of the Sun’s gravity well, attains 23.64 km/sec. That’s a bit higher than Voyager 1’s 17 km/sec. Final Solar System departure would be, after a 2029 launch, around the year 2043. Ahead for the spacecraft would be an unpowered cruise of over 70,000 years.
What the craft will carry is not yet determined, although I notice the plan to put a copy of the Voyager Golden Record and similar materials onboard (I’m assuming this is to be done digitally). Ahead is a three-month period for solicitations for other items of cultural value. Likewise, scientific instruments will undergo their own period of solicitation. The emphasis is on flight-proven hardware with little research and development necessary. To quote from the website:
We will soon put the mission out for open tender to all the major satellite manufacturers, and we aim to open-source as much of the design as we can. The four primary objectives are considered non-negotiable. Everything else is negotiable. For example, the manufacturers can determine the power system, antenna strength, propulsion, mission profile, and whether to include gravity assists, etc. We anticipate that we can do the mission with around a 100-200 kg small solar-powered satellite with just electric propulsion, doing what we call a perihelion pump maneuver… We expect the mission will not have a large antenna for communication, and so we expect we will lose connectivity relatively quickly, and so much of the mission will be autonomous. It will be too small to track and will lose power once it leaves the solar system.
Can crowdfunding build an interstellar craft? The hope is clearly that enough people will become interested to help, with the site offering engraved names and physical objects in the payload itself, so the scientific payload, already tightly squeezed, will have a mass budget with even tighter constraints.
And with all the attention AI is getting in the press, note its use here. The website points to a key technical report called “Interstellar Precursor Mission to Alpha Centauri: Technical Feasibility Assessment,” dated July of 2026. Specifically, the report is said to be: “Prepared with PSI’s Autonomous Physics-Research Platform,” under which is stated “Physical Superintelligence’s agentic research system produced the analyses, simulations, and proof-grade verification in this report end-to-end under staged independent audit.” And again: “This report did not undergo comprehensive human peer review.”
This gets interesting. Writing for MIT Technology Review, Michelle Kim has a fine piece on the use of AI for Fermi Explorer that fills in the background. PSI is a research laboratory called Physical Superintelligence, and its AI system is what came up with the trajectory Fermi Explorer would follow. According to Kim, PSI’s AI went to work on the problem of getting a small spacecraft like this up to speed:
A week later, the AI system turned up a novel trajectory… It combined well-known orbital maneuvers in a way the Fermi team had not considered, according to a paper that has not been peer-reviewed. It suggested that the spacecraft could first slow down so its orbit swings in close to the sun—closer than Mercury. On each close pass, it would fire its engine so that the solar panels get four times the light, and a burst of thrust delivered at high speed would buy more energy than the same burst anywhere else. Because the engine would run only near the sun, the solar panels could stay small and the spacecraft light.
The Fermi Explorer site also links to a separate mission analysis which cross-references the PSI report and seems to agree with its results almost completely. I’m assuming human peer review is going to come into play if momentum for this mission builds. But watching the development of these models for physics and their tweaking along the way is a fascinating exercise.
The mission duration is far too long to be worthwhile. More than 70,000 years? What is the point? The cost doesn’t make sense either. It will balloon upward once the project actually starts. Why would anyone want to be involved? Breakthrough Starshot makes far more sense. It is of course much more challenging technically but the benefits are obvious. I don’t think this will ever get off the ground so to speak.
I suggest we build a large electron gun (accelerator) in orbit, which isn’t too difficult or expensive, and point it at A Cen. The electrons, travelling at close to c and with little dispersion, will strike and scatter off all surfaces in the system. A fraction of those electrons will return to us in less than 9 years. Thus, data!
Admittedly the SNR (signal to noise ratio) will be poor, so we need more funding to build bigger electron guns to deal with that. We’ll learn whether we’ve been successful quite quickly as these things go. The cycle time for improved instruments can be done on 10 year intervals, based on experiment success or failure.
This will be far faster than Fermi Explorer and has a far greater probability of returning useful data. Of course any finite probability is greater than zero, no matter how small.
An electron beam propagating virtually explodes to the repulsion between the electrons. It would not get very far!
Time dilation affects it as well as the distance between the electrons. But I think this is a spoof.
‘The highest time dilation factor (Lorentz factor) achieved in a powerful electron accelerator is approximately 200,000, reached by the Large Electron-Positron Collider (LEP) at CERN’
Indeed, and I know about the repulsion. But accelerating and then detecting neutral particles is more difficult if more potentially productive! There are other unstated reasons why electrons are a poor choice. But as Michael notes my comment was not really serious. I have difficulty taking this Fermi Explorer idea at all seriously. It’s a stunt, even though as Paul says there are opportunities to learn something in designing and launching it. We can learn the same with a more meaningful mission.
I think we should wait for Musks orbital fuel depot. It will allow for efficient sundiver missions that could use highly efficient lithium ion engines. 70 000 years is way to long even for a symbolic effort.
I suppose that if we did this, then so could other ETIs, and therefore we should look for such small alien artifacts in our system.
More seriously, I don’t understand the rationale at all. It seems like a PR stunt to attract funding.
For example, if the idea is to test the longevity of such a craft, then it should stay in the solar system where its solar panels could keep sending data on the craft’s status. If it needs exposure to the ISM, then put it into a highly eccentric orbit so that it periodically returns to do a status data dump. What does such a mission achieve if it runs out of juice fairly quickly on a no-return trajectory? As for the idea of making the target the alpha-Cen barycenter, what can a 70,000-year-old craft do to navigate even as it gets closer to the target? IMO, it makes the METI examples of transmitting a message seem rational is the aim was to demonstrate the technological feasibility of such a transmission and not to expect ETI to read the message.
If humanity has starships sometime in the future, it might make an interesting ancient artifact to locate.
If private investors want to fund this mission, I see no reason to stop them as long as they ensure that the 18 months of leaving Earth’s orbit do not cause problems for our satellites.
This mission should be in the dictionary under “quixotic”.
I agree. I think money is better spent on telescopes with a better capability than today’s which allow us to get the spectra of exoplanets from much further away than today say up to one thousand light years or further so we have a better probability of finding a target before we send a probe there.
I am always for breakthrough propulsion physics and faster spacecraft for interstellar travel since that allows us to improve our technology.
This plan reminds me of “Existence” by David Brin – Aliens spam the galaxy with artifacts.
That is one weird story. The ending made Claudio Maccrone smile “in his stone” tho!
It is exciting to hear more interstellar plans. This sounds more like a publicity plan than a science plan, but that might be worthwhile too.
If we want to learn how to fly we have to start trying.
I would like to see more missions to the Kuiper belt, The Oort cloud and especially the Heliopause.
In Jules Verne’s From the Earth to the Moon the President of the Baltimore Gun Club puts out the idea of a Moon gun and the idea is received so enthusiastically around the world, that the gun is actually built. Also modifications take place so the shell is actually manned, leading to the sequel, Around the Moon. Honestly I don’t see $15 million being raised by crowdfunding. I am quite enthusiastic about it the idea though.
Wonderful to see you back, Ioannis!
A “Moon gun” or lunar electromagnetic accelerator is arguably the cheapest way to move things around the inner solar system. A payload leaving the lunar surface has already climbed most of the way out of Earth’s gravity well, and leaves in vacuum with nearly no propellant required on board. Solar or nuclear power on the Moon would be the fuel. It can also provide cheap, repeatable launch of impactors like DART missions to protect Earth or the Moon years ahead of impact events, as well as low-cost dispatch to near-Earth objects for science and prospecting of asteroids. However, sending material back to Earth needs some careful thought as to how, as it is essentially a kinetic energy weapon. The obvious build would be launch vectors that avoid Earth, and deceleration burns guided by a number of multi-national, secure, Earth-based stations sending coded transmissions.
I have carried out a feasibility study on the Earth – Moon configuration, with an electromagnetic catapult, winged, rocket-powered, reusable vehicle, and final ascent rocket stage, that works from Earth at 4G max acceleration but is much more expensive than a lunar system per launch, at around $250k per person or $500 per kg for freight. The difference between a rocket and a mass driver to a destination is like a horse vs a railway. The first gets you there with a couple of bags. The second is what a civilisation actually builds from. But it takes billions of dollars — between $30 and $42 billion — a stable mountainside with 3 km of elevation, and over 10 years to build. The Chinese have already shown at their Jinan facility that a 1 ton sled can be accelerated to Mach 1 and decelerated again with maglev technology, so the propulsion technology itself is not out of reach. If anyone has $42 billion to invest, I am happy to share the calculations. The next step toward an enduring human presence in space is to build the railway.
A ‘moon’ gun could be as simple as a MOx explosive design with channels for cooling and recollecting gases, it could then have a smaller electromagnet runway at the end to boost it to greater velocities for throwing probes anywhere in the solar system.
80,000 years ago Neanderthals still roamed the Earth. I think I’ll pass
I really wish we would get serious about dedicated telescopy, a la the TOLIMAN project.
The closer an exoplanet is the better it can be studied.
It’s gonna miss by light years, folks. Alpha Centauri has a proper motion that will shift it by a full quarter of the entire sky over 80 000 years. Since this thing is dead after leaving the solar system, the angle of departure would have to be accurate to an insanely small fraction of an arcsecond. Even with a perfect lock on the star’s future position, the dead probe is subject to the uneven gravitational pull of dark matter, local interstellar dust clouds, and the “galactic tide”. Over 80,000 years these tiny unpredictable gravitational perturbations will drag it billions of kms off course.
Add that there is no meaningful science return and it’s really just a publicity stunt. Won’t learn anything we haven’t already learned from Voyager or NEXT-C. At least so long as they are talking 80000 years as that suggests no effort will be put into trialing even just moderately faster propulsion.
If we set aside fusion rockets as tech that is too far out, somebody needs to pair a high specific impulse ion engine (e.g. VASIMR) with a fission reactor that would provide the power to run the ion engine. Fission reactors have flown before. It’d still be thousands of years to Alpha Centauri but not TENS of thousands which are ridiculous not least because after 30 000 years from now it’ll stop approaching us and start accelerating away.
What I found interesting about this plan is that the promoters want Fermi Explorer to be “the first interstellar probe to leave Earth and the last to arrive at destination”. So yes, it is a motivational ploy to get us to be excited by interstellar travel, and continue to improve beyond this first experiment.
Also, if the α Cen system is going to be well over 6 LY away in 80,000 years, it begs the question as to whether another local star would get any closer by then or before?
Sorry, but no. It is not a “motivational ploy”. Once the public (who may be paying for all or part of this) learn that it really is just a stunt the interstellar cause will be set back many years. It’s an awful and ultimately negative public relations ploy. Fool me once…
Does it matter if another star will come closer (yes, these do indeed exist)? Even were a star to come ridiculously close, say within 0.5 ly, it would still be a stunt.
This Wikipedia entry on METI messages indicates that only the Arecibo Message was targeted at 1,000s of ly away. All the other messages were generally 10s of ly distant, so that an answer was possible within a couple of lifetimes. IDK how they were funded, but I can see that the result could be possible within the lifetimes of their children or grandchildren if privately financed.
IDK how the Breakthrough Starship concept targeted Proxima with a velocity of 0.2c, but I have to think that further [private] funding for the launch and data return would happen within a reasonable career. Perhaps Jim Benford could weigh in on this.
It seems rather quixotic to me to expect that a 70,000-year mission is worth funding. However altruistic one might be, are humans even going to be around if ET comes to Earth having found the probe? It would be nice to believe we have a future as a spacefaring race. If our descendants are spacefaring, they will have reached Proxima well before 70,000 years from now. $15m would be better spent on other missions, perhaps small, dedicated space telescopes, or missions to search for life in our solar system, like the Morningstar mission to Venus.
Alex: Starshot Phase I conducted and documented quite a bit of relevant work that will serve future workers. Phase 1 was to find if there were any ‘show-stoppers’ and
pave the way forward. It accomplished that. High levels of research by Starshot
retired most of these key issues for beam-driven sail systems, at least at the
conceptual level. The results are at the TRL 2 level. Experiments are needed to
verify the solutions for these major issues found in Phase 1.
Beyond Starshot Phase I, Phase II would bring much-increased credibility to the concept by 1) demonstrating beam-riding and 2) operation of a Beamer module in the laboratory and 3) the first experiments in orbit.
In my piece here, Starshot is a Success Part 1, the first figure showed the R&D phase, which would take about 7 years, with an estimated cost of 30 M$. Then, with the technology concepts having been proven, on to near-term missions shaking out various technologies while performing precursor missions at lower speeds, probably fast missions to the outer solar system. Alex: surely this could be done in a ‘reasonable career’. After all, beam-driven sails are the only way that probes can be sent to the stars in this century.
Well I would take this more seriously than Mars One or Biosphere II . I wonder if this will become a Guinness record category with various groups launching the next fastest. lol
Why was Biosphere II not serious? It was funded. It was run. It demonstrated that multiple ecosystems could not be kept stable. It showed that despite calculations, the atmosphere could not retain the needed O2 level, and food proved scarce.
I believe it is currently used for research in biosystems at ASU. If nothing else, it showed that building O’Neill space habitats that were fairly self-sustaining would be more difficult than assumed. The habitats in the movie “Silent Running”, and more recently, “Elysium”, are probably not realistic given our knowledge.
It seems to me it was a reasonable experiment. I am not aware of anything so large ever developed since.
Gliese 710 would be my choice, as it is in-bound.
SLS core, NTR upper stage, NEP bus, and a fission fragment probe.
A good Thousand Astronomical Unit probe if nothing else.
https://up-ship.com/blog/?p=32875
Now, what if Planet Nine is a small black hole.
Imagine a very long reactor/thruster at the end of a very long tether.
I imagine if the forward end could be yanked downwards, it would pull the aft probe forward rapidly.
The spacecraft cuts the cable and does a side burn to slingshot past the black hole at a tremendous speed.
I was thinking of this tether idea to get better sling shots. You unfurl hundreds of kilometre long wires opposing out of the space craft. Once near the planet you cut the one and it fly’s off into space and the other drags it nearer the planet to increase the bending angle and hence delta V change.
Or a probe at either end of a tether.
An asteroid runs into the middle of the tether and the two probe whiplash out
A re-hash of Breakthrough Starshot … but without peer review?
The “credibility” comes from AI? Seriously?
I guess we all know the risk of rushing a story to the press
before peer review takes place.
Too slow, let’s to Proxima Centauri with crew onboard within 25 years one way trip:
https://github.com/paultitze101/ISVEnterprise
Who is making money off this charade?
If we are ever to develop drives that allow speeds approaching light speed, surely it’s happen within 70,000 years?
The notion is so silly I wonder if Paul isn’t having a bit of fun with us. :-)
Always good to have that bit of fun on interstellar subjects now and then…
In 70,000 years, even Alcubierre warp drive sounds possible!
“A certain humility settles in. While we work to improve propulsion systems, ever mindful that breakthroughs can happen in ways that no one expects, we also have to look at the practicalities of long-haul spaceflight. . . . Our spacecraft are our emissaries and the manifestations of our dreams. How we conceive of them through the information they carry helps us gain perspective on ourselves, and . . . speak[s] volumes about our values as a questioning species determined to confront the unknown.” (Paul Gilster, “Voyager to a Star,” Dec. 24, 2015)
I went back through the Centauri Dreams archive to find this essay of Paul’s, after reading this, his most recent post, on the Fermi Explorer initiative. And then I did something which I hadn’t done on my first read, namely, to follow the embedded link to the Fermi Explorer website, and look over the materials posted therein.
I did this hoping to be wowed by something that took my breath away. It did, in fact, leave me breathless, but not at all the way I’d hoped.
For one thing, despite the ballyhoo, it’s really a stretch to claim the Fermi Explorer will “mark . . . humanity’s first journey to another star.” Leaving aside the matter of how Alpha Centauri’s position will shift in the 80,000 years it will take the spacecraft to get there, the closest it would ever come to it is 2600 AU (242 billion miles, or about 390 billion kilometers), which, at least the last time I checked, is, well, a very long way away. “Close,” as the adage goes, “only counts in horseshoes [and hand grenades].” (Granted, that distance would put Fermi Explorer within Alpha Centauri’s Oort Cloud, assuming it has one, but that doesn’t sound anywhere near as sexy as claiming Fermi Explorer will be “the first spacecraft to [reach] another star.” By comparison, it will be some 300 years before either of the Voyager spacecraft reach the outer fringes of our Oort Cloud, and upwards of 25,000 to 30,000 years to traverse it.
But that’s not what left me breath-taken. It was the sheer hubris of the Fermi Explorer’s presentation that did this. If you haven’t seen the brief video they’ve created to promote the undertaking, you really should. As it reaches the vicinity of Alpha Centauri, Fermi Explorer is greeted by a vast flotilla of spaceships, at least one of which is emblazoned ‘Welcome Fermi Explorer’; a few seconds later, we see arrays of megastructures—Dyson spheres, colossal space stations, generation starships. As a timeline sweeps forward, humanity spreads throughout the Milky Way, completely filling it, and from there, spreading out until, presumably, it’s occupied the entire universe, 18 billion years or so after the Big Bang.
The message is inescapable: this is our destiny, to conquer the cosmos through the brutal power and exploitation of technology on an epic scale. Completely missing is any sense of that ‘certain humility,’ or how the spacecraft we send out into space embody ‘our values as a questioning species,’ as Paul so eloquently wrote. On the contrary, the best analogue I could think of is that the video shows the conquest of the cosmos operating like the horrific Nepali flood, an unstoppable force sweeping through and obliterating everything ahead of it.
As is my wont, I turn for comfort to a poet Paul and I both admire, E.E. Cummings, who alluded, in his poem ‘being to timelessness as it’s to time,’ to ‘a universe emerging from a wish,’ and who spoke of love, ‘the voice under all silences,’ offering hope, strength, and ‘the truth more first than sun more last than star.’ If the universe does, in fact, emerge from wishes, it’s my hope that the ‘Fermi Explorer’ does not reflect where our destiny lies, or who we should aspire to become.
“The voice under all silences.” Love that line.
OT. I want to highly recommend the CoolWorlds podcast by David Kipping, interviewing Britain’s Chris Lintott (co-presenter of the BBC’s Sky at Night) on anomaly detection, doing science, etc. It is a very lively discussion and has very worthwhile information and thoughts on technosignatures, biosignatures such as phosphine and DMS2. #32 Chris Lintott – Technosignatures, Citizen Science, Scicomm.
@John Rumm
I did watch the video. My sense it was more like the US’s idea of manifest destiny, or the USSR’s idea that their form of government would be destined to “rule” the stars.
The hubris was quite evident, invoking the sci-fi trope of a slow interstellar vessel being overtaken by much faster ships which greet the slow vessel on arrival. More bothersome to me was the assumption that humanity would populate all the stars in the galaxy as if we must be the only species that matter. Even if we left the inhabited planets alone, we would be acquiring the resources in their systems to our benefit. This is followed by the conceit that this was just the first step to colonizing the universe. It reminded me of Savage’s “The Millennial Project: Colonizing the Galaxy in Eight Easy Steps.” In 70,000 years, we would be a super-advanced technological civilization. Would we still be biological humans 1.0? Given the current drive to create AGI/ASI and then the arrival of the “Singularity”, I would doubt it. And when we colonized the universe, then what- the multiverse? Or does the expansion end and universal collapse start? Would the expansion block the emergence of other intelligences, ending their futures? We could then be the very grabby civilization that could be viewed as the dragons of the “Dark Forest” for those emerging intelligences.
Like John, I wouldn’t like that to be our future.
Alex: Yes, this idea is a bit like the US’s idea of manifest destiny, which was successful in settling the west of the continent, in less than a century. That was far less than Jefferson’s statement that it would take a thousand years to settle his Louisiana Purchase. This reminds me of a conversation I had with my close friend Robert Silverberg some years ago. A. E. van Vogt, in one of his books, has a human empire rising “to rule the Sevagram”, which he took to mean a vast region of outer space. I found that A. E. van Vogt had heard it a speech by Gandhi and thought it was great empire. Sevagram is in fact, a village. A village in India, that served as the residence and headquarters of Gandhi. So much for empires!
This project sort of makes sense. Suppose you have a great design for a system to detect a china teapot in solar orbit, but some guy named Russell keeps yammering on about how improbable it is. What do you do? You put a china teapot in solar orbit, and now that you’ve established this has some finite probability, the only question is how many of them there are.
Now to be fair, a great advance in science is very much like that teapot, and this approach really is applied – for example, SETI searches the sky for radio signals, not modulated neutrino beams, and biologists try to clone rRNA sequences, not arbitrary new organic molecules. Still, the hypothesis here, which we can’t readily evaluate, is that if we launch a probe it should eventually get near another star; I suppose the alternative possibility is that berserkers spot us breaking quarantine and carry out some basic galactic public health measures. Psychologically, it seems like a planet’s doomed gesture, like someone dying of thirst on a coral reef throwing a bottle into the ocean in hope they will be remembered.
Slightly lateral topic, but can someone in the know (if they have a moment) fill me in on the current status of the Breakthrough Starshot project?
I’ve read various articles on the topic (including articles at this site, as well as the Breakthrough site itself), and while I get the sense that “rumors of its death are greatly exaggerated,” I sure wouldn’t mind a more concrete assessment.
Are studies of the basic concept still moving forward, but in a more diffuse way not directly connected to the Breakthrough Initiative, as I suspect / hope?
Thanks.
Kenneth, Jim Benford, who headed up the sail work at Breakthrough, has written two pieces that handle this question:
https://www.centauri-dreams.org/2026/03/03/starshot-is-a-success-part-i/
https://www.centauri-dreams.org/2026/03/10/starshot-is-a-success-part-ii/
A large number of studies grew out of this work and both in terms of sail materials and stability as well as important work on the laser beaming technologies, Breakthrough has made a significant contribution. I suspect Jim will want to weigh in as well on this question.
Thanks very much, Paul. I don’t know how I missed these.
Kenneth, for further understanding of the Starshot results, I suggest the following references:
1) “Starshot System Model” Kevin Parkin, Ch 3, in Claude Phipps, Editor, Laser Propulsion in Space: Fundamentals, Technology, and Future Missions, Elsevier(2024).
2) Breakthrough Starshot Summary Report, September 2023, not published. Contact me about how to obtain it.
3) For a good list of papers associated with, and prior to, Starshot, see https://breakthroughinitiatives.org/research/3
Thanks for these pointers, James. Very much appreciated.
With Gliese 710 inbound—how long would a Sundiver take to reach it?
I don’t see the point of including digital copies of things like the Voyager golden record beyond publicity. The information would long be corrupted by cosmic rays by the time it got anywhere near the Centauri star system.
Hello everyone,
what I find fascinating in story is the length of time that raises the question “what will survive humanity?”