The UK nuclear propulsion startup Pulsar Fusion has dreams of propelling rockets to destinations from the Moon to the outer solar system — but first, they’re headed to Texas. Why? Get closer to potential US clients and investors, of course. For over a decade, Pulsar has been studying, developing, and testing its nuclear propulsion tech. It's getting to be time to step up the level of efforts.
Pulsar’s nuclear fusion spacecraft—Sunbird—consists of a dual direct fusion drive (DFDD), and eight Hall-effect thrusters. Together, these should provide the massive thrust capable of reaching speeds of 329,000 mph, and the smaller pulses needed for precise maneuvers.
If you're used to reading about the speeds of probes we send up, 329,000 miles per hour sounds pretty fast; for example, when the Parker solar probe dove close to the sun last December, its speed peaked at 211,194 mph and that was fast. The speed of light, though, is 186,000 miles per second. There's 3600 seconds in an hour, multiplying that 186,000 by 3600 seconds per hour results in light speed equating to 670,000,000 miles per hour. Speeds like 329,000 mph might shave whole digits off the flight to outer planets in years, but is dreadfully slow of what would be needed to go to other star systems.
That said, their DFDD engine appears to be actual nuclear fusion and not a clever renaming of some other phenomenon.
Pulsar plans to test its nuclear fusion tech in space by 2027, and is expected to test components of the Sunbird’s power system in orbit as soon as this year. In the meantime, the company is ramping up its ground-based tests.
- Pulsar is test-firing its Hall-effect thrusters to demonstrate their technical capabilities; it has also signed an MoU with Thales Alenia Space, which has shown interest in the electric propulsion tech.
- Pulsar also recently built two space grade vacuum chambers in England—the largest of their kind in the UK—which it will use to conduct endurance tests for its Hall-effect thrusters, and its Sunbird fusion spacecraft.
Here and now: Nuclear fusion propulsion has long felt out of reach, but thanks to AI, Pulsar officials say they have been able to refine the complicated propulsion technology to make it an operational reality. The company is using AI to help make their nuclear fusion reactors smaller, more intelligent, more precise, and ultimately, more practical.
Pulsar’s MarsEffect 10kW thruster, which has been test-fired under a UK Space Agency grant for Nuclear Electric Propulsion. Image: Pulsar Fusion
Perhaps converting to horsepower might be useful: 1 HP = 746 watts so these 10,000 W thrusters reduce to 13.4 HP
Sorry for my ignorance here but is this a reactionless drive?
ReplyDeleteReaction mass limits has always been a limit.
I tried looking up hall effect but it was unclear at best.
Not an inertialess drive. Hall effect thrusters are a variety of ion engine. Should be pretty high specific impulse, so efficient, but in any ion drive the thrust you get is generally pretty low compared to the mass of the thruster.
DeleteThat's what I was gonna ask, specific impulse data, anyone?
DeletePsyche used Hall effect thrusters. Here is an explanation.
Deletehttps://psyche.ssl.berkeley.edu/2018/01/19/electric-thrusters-psyche-spacecraft-work/
John Wilder? Thee John Wilder?
DeleteHere you go. (pdf warning)
https://electricrocket.org/IEPC/35_2.pdf
About 3000s ... Not bad.
DeleteThe problem is the same as any electric thruster, though - thrust goes with momentum of the exhaust. The momentum goes as the square root of the thruster's operating voltage, but power to run it goes linear with the voltage. So all else equal, doubling the power to the thruster gives only a ~40% increase in thrust.
Rick, and Anon - or Anons - Thanks for answering that. I find this ... interesting. The answer to "not much thrust" is to run low thrust continuously. It has been talked about forever, but that's all I know about it.
DeleteMuch like refueling in space, reusable rockets, slinging payloads out of a giant centrifuge and other things we're seeing regularly now.
RE: low thrust
DeleteRun continuously, or made more efficient.
My understanding of the Hall effect is through ionization, the particles are more confined, or narrowed, in a stream. The result is increased efficiency.
Hi, SiG, same anon here as the above two.
DeleteRefuelling is a fun problem. With ion thrusters the upside is you need only transfer a single propellant, and it's probably not corrosive or explosive. The downside is, if something like xenon, it's likely to be even harder to produce (or, extract would be a better word choice) when at the destination than conventional fuels.
Rick: it's not confinement as such, the exhaust stream can spread out as much as it wants after it leaves the nozzle - the thrust has already been delivered at that point. The thrust you get per unit mass of propellant consumed is proportional to the speed of the propellant as it leaves your ship.
In a conventional rocket engine you get that speed through heating the propellants via combustion. In an ion engine, you ionize the propellant and then use an electric field to accelerate it. That can give you a higher exhaust speed than a chemical rocket, so, more efficient in terms of thrust per unit mass spent.
Conventional propellant engines are really good at tossing out lots of mass per unit time, which translates to lots of thrust in absolute terms. It's the spaceflight equivalent of "no replacement for displacement."
They probably left the UK in order to escape the regulations and the political climate, which, today, is not friendly for innovation or anything nuclear.
ReplyDeleteNow, is that speed the top speed or are they talking about acceleration?
Top speed, which is probably based on the speed of the ions/particles exiting the thruster. Top speed for space thrusters is pretty meaningless in actual use Isp and thrust to weight (including all thruster systems including propellant). Without information on the nuclear propulsion (Hall Effect thrusters are common on satellites) I think that to get something up to that speed would not be feasible for a real spacecraft - you would have to fire the thrusters for a very long time, and expel a large mass of propellant (then you need bigger thrusters to accelerate a spacecraft with larger propellant tanks with more propellant, and also larger structure to support the larger tanks and propellant...
ReplyDeleteAs a side note, I don't like start-ups that use a bunch of techno-babble to fool potential investors and customers while not providing any real information on the progress and promise of the startup (remember Theranos and Elizabeth Holmes?). After going to the Pulsar Fusion web site they don't provide the truly useful information (on nuclear propulsion) that would allow and assessment of feasibility and real world performance.
Thanks for the addition. On not liking startups that use a bunch of techno-babble, my impression is that it's hard to find startups that don't do that. I looked around on Pulsar Fusion's website for a while and didn't get much out of it.
DeleteThe success or failure of a startup is in that gap between getting the first idea to pass the first test and then scaling up to the goal. The saying that keeps playing in my head is the "uncanny valley" in robotics, but it isn't exactly that only similar. What peaked my interest was the term "direct fusion drive" being thrown around. In my mind, fusion is tightly coupled to the term "hydrogen bomb" which makes me think of lots of energy being released, but I can't find anything that explains what they mean.
There has been talk for decades about fusion drive that would periodically emit a small fusion bomb. Is that what they mean? I don't think so.
I seem to recall reading about laser pumped fusion, maybe something like the national ignition facility at livermore was pursuing. If that is what they are doing, then the propulsion system has considerable support mass: high power system, lasers, etc. I wouldn't invest my money in this startup. I have a friend who funded a bunch of new technology projects, he and I disagreed on the approach to new technology - I want to list all the difficult issues, and figure out a plan of attack where the biggest/hardest are prioritized. He thought that pursuing the easier issues first was better, you can be seen to making progress, you don't kill off you project early because you run into an intractable issue, and you can continue your funding stream (at least for a while). It also has the advantage of giving you more time to solve the hardest problems. Most startups purse the later (provides larger, longer funding streams, the teaching the horse to sing approach (see: the mote in god's eye"), while internal investment in existing companies more regularly uses the first approach (saves money, resources)
Delete