Pulsar Fusion is creating fusion rocket able to move astronauts at 500,000 mph which is twenty times faster than the 24,791 mph speed of fastest a crewed rocket has ever flown. The company has raised over $133 million in funding across 19 funding rounds with 65 investors.
Pulsar recently partnered with aerospace R&D company Princeton Satellite Systems (PSS) for a study that will use AI to model the behavior of hot plasma in a fusion rocket engine. It has also announced that it has begun constructing an eight-meter fusion reaction chamber in the UK.
Its goal is to begin firing that chamber in 2025 and achieving fusion temperatures by 2027. The next step after that would be conducting a test firing in orbit — proving that a fusion rocket could potentially power the next era of space exploration.
The Direct Fusion Drive is a revolutionary steady state fusion propulsion concept, based on a compact fusion reactor. It will provide power of the order of units of MW, providing both thrust of the order of 10−101N with specific impulses between 10,000 – 15,000 seconds and auxiliary power to the space system.
Pulsar is developing non-fusion products that could bring in revenue. They are working on a Hall-effect electric thruster for spacecraft and a second-stage hybrid rocket engine. Pulsar Fusion is partnering with the University of Michigan to research electric Hall-effect thruster tech. The UK Space Agency is funding the collaboration.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.
A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.
OK… All I know about sustainable nuclear fusion is it’s been 10 years a way for 75+ years. Longer than I’ve been alive. (Not by too much, actually) I’ll believe it when I see it. And I will dance in the streets when that happens. (If I live long enough) Please, make my day, year, and life! Good luck to all working on this most complex of engineering projects.
Definitely should not consider DD or DT fusion, because they output most of their energy in neutrons, just fine if you are just converting neutron energy to heat for power generation but quite useless if your intention is to use momentum of very fast charged particles directly as thrust by electrically steering them; for that you need to maximize energy in fast charged particles.and absolutely mninimize energy in unstearable neutral neutrons. As aneutronic reactions go He3 fusion looks best because as noted by Brett Bellmore p-Boron has a high coulombic barrier. And although He3 is presently rare it would not take long to change He3 from unobtainium to abundant fuel. It has been long demonstrated that Tritium can be mass-produced in slightly modified FISSION reactors with lithium control rods and 5% of that tritium would spontaneously decay to helium 3 every year. I am not talking about the exotic proposed He3 breeding FUSION reactor proposed by pulsar, but a conservative fission design well proved at Watts Bar.
Wow. It never ceases to amaze me…. raising $133M with hopeless vaporware. Imagine what you could turn that money into! Just imagine $133M of farm equipment for some developing backwater… the rich are as clueless as the clones.
Tell you what: earn $133 million yourself and you can spend it on whatever charitable cause that you want rather than griping over how people spend their own money.
Well … I have to say: Chutzpah is running in high gear for these folks. And, who knows, maybe the hubris is warranted!
Boring though it may be, ‘the numbers’ also need to check out, and in particular answers to several hard questions of ultimate viability need addressing.
F = ma … where
a = Δv/Δt and
m = Δm/Δt
Setting (Δt = 1) for 1 second (its convenient, right?) then Léts the above collapse into
F = Δm⋅Δv
Which is to say, whatever the outflow of reaction mass (Δm in kg/s) times whatever its actual exhaust velocity (true of ALL — as in 100% — rocketry schemes) in m/s then gives the pushing force on the rocket’s remaining bits.
Why does it matter? All sorts of reasons!
First, you can take something like the quoted ‘10,000 to 15,000 ISP’ above and convert that to ΔV easily enough:
ΔV = ISP • G₀ … where
G₀ = 9.81 N, the ‘standard G’ of Earth’s attraction
ΔV = (10,000 … 15,000) × 9.81 → ~(100,000 to 150,00) m/s
‘They’ also quote Δm rates of … hmmm … they didn’t.
BUT, we can figure it out readily enough:
F = Δm⋅Δv
Δm = (10 to 101 N) / (100,000 to 150,000 m/s)
Δm = 67 to 1000 mg/s (milligrams/s at the extremes)
Thing is here, if we move from milligrams per second to kilograms per day (useful for such low acceleration forces), then it becomes
Δm = 5.7 to 87 kg/day (at extremes)
Doesn’t seem too bad of a ‘drip rate’, right?
Le’s see if this works ‘backwards’ from the advertised velocity numbers. 500,000 mph.
500,000 mph ÷ 3600 s/hour → 139 mi/s × 1610 m/mi → 224,000 m/s.
Making an assumption or two about how much mass is invested (say 66%?) then Tsiolkovsky’s Rocket Equation is helpful:
ΔV = ISP • G₀ ln( 1 / (1 – burnup) )
ΔV = 15,000 × 9.81 ln ( 1 / ( 1 – 0.66 ) )
ΔV = 162,000 m/s
Hey! That’s pretty good! If the guess were 75% burnup (saving say another 15% for slow-down), then the numbers come up to 200,000 m/s.
WHICH is about exactly the claim. Assuming a before-fusion-turns-on ΔV of 25,000 m/s.
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So, the numbers seem to work out pretty well indeed. Does one need a rocketry PhD? Nope, not for these High School equations. Yah, sure, gotta remember them of course. But still, they vet out.
One could go further I suppose and ask how many days of acceleration needed. Tsiolkovsky’s equation doesn’t help in that regard, except to tell us that ⅔ of the original rest-mass of the rocket needs burning up. From the 5.7-to–87 kg/day equation, we COULD figure it out, if only we knew the starting absolute mass. Which we don’t. So, we’re stumped in a way.
The Wild âhss Guess WAG would be, there’s no way to make a big old superconducting fusion platform without a whole lot of magnet coils, cryogenic bottles to hold the precious gasses, big ol’ electrical systems (utilizing a LOT of power to ionize the gasses, if nothing else). Lots … of stuff. 20, 30 tons? Well, helpfully, the burn-up mass of ⅔ then tells us the rest mass is 100 tons at the outset. And that 66 tons is expendable fuel. And at 5.7 kg/day, would take some 11,700 days. 31 years. Ouch. Well, at the faster rate, 87 kg/day we get 2.1 years. MUCH better.
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The ‘hard question’ is, what fuel? Clearly, proton-boron aneutronic sounds awesome if possible. But its energetics are so far removed from what has been researched (to death) in the last 75 years, that really only some variation on deuterium-deuterium (cheapest, by far) or deuterium-tritium (supposing big new facilities to breed the stuff) come into being.
The TOTAL amount of tritium, intentionally produced between 1956 and 1996 (according to Wikipedia) was 225 kg. Since there’s no practical way to recycle the tritium from a D-T gas mixture running the fusion core, it becomes precious reaction mass. The aforementioned 66 tons of fusion fuel would need to be approximately 40 tons of tritium. Wow. Not this week!!!
So, supposing that this is a non-starter, then D-D becomes much more realistic. Seawater is ¹⁄₇₀₀₀ deuterium-to-hydrogen ratio. Variations on precision distillation of water to enrich deuterium, followed by selective electrolysis can produce immense amounts (with a LOT of input energy) over fairly short periods of time. Heavy water, and all that.
All this then puts light on the very attractive p-B proton-boron angle. Boron is almost as cheap as dirt, and of course hydrogen (protons) have no limit of readiness. We drink kilograms of it every day. H₂O!
Other hard questions are along the lines of where’s all the oxygen coming from for the astronauts. I guess plants, algae could be used to recycle it from carbon dioxide. Would have to, for a multi-year mission. And there’d be plenty of light from fusion itself, albeit not necessarily in the helpful wavelengths for algae. Oh well. Gene splicing!
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⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
There already is a solution (if the machine works out).
Helion Power, well funded now, patented a process for H3 and tritium production from DD fusion. They would both use and sell these products. For their own power production operation they plan on using one machine for production of tritium and H3 as that machine would become radioactive during use, as it is neutron rich. The other machines would fuse D and H3, aneutronic energy production. They have a nice 30minute video showing the plant detailing the machine and patent. (Find on YouTube, “A New Way to Achieve Nuclear Fusion: Helion” by “real engineering”, 30 min.)
Now, my only question for Pulsar Fusion is…. How are they planning to power the magnets before fusion kicks in? How much juice do they actually need for the squeeze? Did they explain this somewhere outside of investor-only info?
I must say, fusion is advancing rapidly in this very interesting decade. We could have commercially relevant working demonstrators in the next five years. The masses of some of these fusion devices and ancillaries are within Starship range.
Actually, these fusion components, reactors, ancillary cooling mediums, cooling components (especially in space, radiative cooling only) and shielding and plumbing amounts to a MINIMUM of several thousand metric tons, and some of the components are NOT divisible (do not lend well to assembly in orbit as they are one piece, like the reactor itself (250 metric tons). Starship Heavy is NOT enough.
Besides, fusion for commercial power is not just 10 or even 30 years off. It’s MORE. Fusion for space use is further off in time than commercial fusion for power is. A fission reactor of several hundred megawatts is MUCH more feasible; but even so, with such low thrust, on a trip to the moon, existing chemical rockets would be faster, no contest. Mars would not save much time if any, due to the low accelerations. To Jupiter and to the outer planets, it would save some time, but with only several hundred pounds of thrust, and a multi hundreds of ton spacecraft, your looking at many months just for the acceleration phase, and many months to decelerate to allow standard planet of moon capture.
Fusion for power generation is a crackpot idea. Direct fusion propulsion, where momentum of fast charged particles is used directly for thrust, is a far more practical, far easier application of fusion energy. Power generation is not a preliminary step. If fusion for power generation ever beats breakeven, many decades after fusion for propulsion is commonplace, it will still be the very worst possible way making heat for steam turbines. Fission power is the solution for that application.
Yes, the calculations mainly show that the thrust and resulting acceleration rates to the closer planets, mean a chemical rocket is still faster. Oh yes, and its worse than you stated for the spacecraft mass. 100 metric tons is far to light. That’s like trying to build a 500 KG Tesla Plaid S. Its not happening, this century. The fusion components are just too heavy. The reactor system, the plumbing, the shielding and the cooling system (which for space use is a bigger headache than Earth based fusion, or fission systems, because only radiative cooling is possible in space). With everything, your looking at least 1,000 to 1,500 tons. The reactor system would require hundreds of negawatts minimum to make it work, and at least 15,000 to 25,000 lbs of thrust, and even at that, its still months of acceleration intervals to accelerate, then decelerate. Also, nuclear fissiin reactors are much more feasible, commercial fusion is not just 10 years away like has been reported. More like 50+.
Well, of course it is all presupposing a whole lot of scientific magic. Serious amounts of it. Yew and elm wands!
There are so many ‘well … there’s that’ issues that it can make one’s head nod.
THE MAGNETS – superconducting? Just about the only way to make them light-weight enough and low-power enough to not become as a group the totality of the empty mass of the vehicle. But (drumroll), superconducting magnets generally need to be kept ridiculously cold. How cold? On the order of liquid-hydrogen cold.
So you say, but Goat! There’s tons and tons of liquid deuterium aboard! Yah, and so what. What happens when we use that LD₂ to cool the necessarily always-being-heated-by-neutrons magnets? It evaporates. Will that be at the convenient 87 kg/day rate? Mmmm… no, actually much higher.
So following those crumbs, how does one reliquify the deuterium? Cryogenics, of course. Bulky, requiring either motors or acoustic coolers or both. Lots of radiators. Did I mention ‘total mass’ issues? Yep, radiators.
More crumbs. Radiators have so-called working fluids. You know, hot in, cold out fluids. They might be as simple as helium gas, or the deuterium gas itself (why not? right?), or more indirect, since it’s all about getting rid of the compressed heat of the deuterium gas BEFORE it expands back to a liquid state. Cryogenics. Complicated stuff.
The downside for using compressed helium as a working fluid is that it leaks out of everything not welded closed. In a multiyear trip, such leakage is death. You can NOT go to the party store and buy more helium along the way. Nope. Moreover, whizzing around the Solar System at 500,000 m/s means that even the ittiest-bittiest particles of space dust intercepting (“hitting”) our radiator plates make big gashing holes in them. And there goes your helium. In minutes. Gone.
Oh well, that just means you gotta store a whole lot more aboard. Dead weight. And a lot of space-rated superglue and duct tape. (SMILE!)
So, taking all that into account, we might be able to keep those superconducting electromagnets cold enough for days at a time, weeks. But then the problem as (BRETT BALMORE) says, is the the inevitable wash of high-energy fusion neutrons (from all the unavoidable side-reactions) upon the exquisite superconductor ‘stuff’ (through cladding and everything, being neutrons and all) changes our superconductor to not-a-super-conductor. Which is a BIG damp squib in the whole scheme.
Hmmm… the only way out of that corner is to have manufacturing-in-space facilities to melt down the now crudded-up superconductor, purify it, recast it into new wire, and fabricate new coils every few weeks. That’s going to be some magic right there. Powerful magic. Jackie Chan magic.
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Note — we haven’t even gotten off the practicalities of superconducting magnets yet. Or the remarkable power systems to re-energize them once they fail. Batteries? Yep, a lot of them. Think Teslas per-car mass: and that’s only 100 kWh, and it takes 600 kg or ⁶⁄₁₀ of a ton. Your basic 12 tesla (not capitalized!) car-sized magnet holds no less than 75 kJ per liter. Given the volumes (as shown) involved, we’re looking at thousands of liters. Space-ship sized. 250 MJ … per magnet. And there’s what, 10+ magnets? A lot of power.
Anyway. Enough for now.
⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
Helion is close to commercial fusion using similar FRC concept with no superconducting.
Even just using deuterium fuel is super-expensive. >$1million a tonne. Given fusion alone can have Isp’s >1000000m/s it seems likely they are also using cheap hydrogen as added diluting reaction mass -maybe injecting orders of magnitude more than fusion fuel into fusion products to increase thrust after it has been used to provide cooling.
P-B fusion is really only attractive if you don’t look too closely. It’s got a terrible cross section, 500 times worse than D-T fusion, and the ignition temperature is almost ten times that of D-T fusion, because the Coulomb barrier is very high due to Boron having a +5 charge when fully ionized.
When you consider that thermal radiation is T^4, and that charge makes Boron radiate like mad, achieving P-B fusion outside of an optically dense plasma seems like a non-starter.
P-Li would be much more plausible as an aneutronic reaction, and it’s not even easy.
Seriously, if you’re doing a fusion rocket, might as well use the easiest reactions, and just accept that it’s going to have a limited run time before it kills itself with neutron activation.
I mean, I love LLP’s research, for instance, but going for aneutronic fusion out of the starting gate seems a bit much.
Pulsar has to be aneutronic. Neutrons are fine for power generation where their energy is just converted to heat, but quite useless for pulsars concept of using the momentum of superfast reaction products directly for thrust by stearing them electromagnetically, those products must be charged. As you say p-B has a high coulomb barier so He3 fusion (WITHOUT deuterium) is more promising. Helium 3 is now unobtainium but can become an abundant fuel by mass producing tritium in fission reactors equipped with lithium control rods, proven at Watts Bar, and just letting it decay spontaneously to He3 at 6% per year.
At least it’s not another mindless and brutish nuclear thermal design.
The way they assemble the rocket on the ascent, they must have found rocketry’s Holy Grail of chemical single-stage to orbit or designed chemical engines so versatile that they can be throttled with high precision while still maintaining considerable thrust to be able to take the payload out of the Earth’s gravity well. Fusion propulsion is promising but this flick is just ridiculous. Why not just assemble the spacecraft in orbit and let it stay in orbit, and just shuttle resources and crew to and from it?
What rate of acceleration and deceleration is this rocket capable of? Is it 0.001 g like an ion rock? Or is it something respectable like 0.1g?
The Thrust listed is rated in newtons, which is kg of force, so converting to lbs makes their estimate about 22 to 222 pounds of thrust, not a lot but you can trust the thrust to keep thrusting throughout days, weeks, months, possibly years, which reallllly gets fast.
Think of it this way, with a chemical rocket you can get say 100,000 pounds of thrust for a minute.
Or with something like this you could get 100 lbs of thrust continually for a week, which ends up to be about ten times more thrust over time.