The Large High Altitude Air Shower Observatory, or LHAASO, in China has just detected an extremely high energy particle from some unknown particle accelerator in the galaxy, 140 times more powerful than can be produced by the Large Hadron Collider.

These particles can be focussed and directed using electromagnetic 'lens'.

Three months later, they confirmed that the mysterious space traveler was from the Milky Way Galaxy and was packing a staggering energy level of 1.4 PeV. That is 140 times higher than what can be achieved by the Large Hadron Collider, which is near Geneva and is the most powerful particle accelerator on Earth. It is the highest recorded energy photon to reach Earth to date.

This proved that PeVatrons, or PeV accelerators, exist in our home galaxy, but exactly where and what they are remains a mystery, according to the study. Within 11 months last year, LHAASO found a total of 12 potential PeVatron candidates in the Milky Way.

If some future technology is developed such that these galactic accelerators are discovered and able to be harnessed, how can the energy from these particles be converted to useable energy to power a huge generation-type space habitat?

I am thinking something like 'solar panels' that are able to handle these extremely energized particles.

I am not concerned about efficiencies. The reason for using such a method over any other energy source is a plot contrivance, and beyond the scope of the question. Assume that there are very good plot reasons for wanting to use this energy source.

Clarification Edit

The intent is to use these high PeV particles themselves, not their byproducts, until they reach the ship. These particles can be directed and channeled through EM fields to properly 'aim' them at the ship as it moves. Gamma rays/particles can't.

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    $\begingroup$ Are you looking to generate power from the high-energy protons produced by a PeVatron, or from the high-energy photons those protons subsequently produce? As a side note - it seems like the title and body of your post ask different questions (propulsion vs. simply energy generation). $\endgroup$
    – HDE 226868
    May 30, 2021 at 16:09
  • $\begingroup$ Surely if you wanted to use one for propulsion you'd just point it backwards and hold on? $\endgroup$
    – JeffUK
    May 30, 2021 at 19:07
  • $\begingroup$ @HDE 226868 I am hoping for enough energy to propel the spaceship as well as power it. What I do not want is for the impact of the particles themselves to propel the spaceship like a sail. I also do not want the mechanism for propelling the ship, just the method to convert the particles to useable power. $\endgroup$ May 31, 2021 at 1:38
  • $\begingroup$ Cosmic rays are already have gone well past this. en.wikipedia.org/wiki/Oh-My-God_particle As an energy transfer mechanism it will be comically inefficient. $\endgroup$
    – puppetsock
    May 31, 2021 at 17:04

4 Answers 4


Your solar panel idea will work; it simply won't produce a whole lot of energy. But it will certainly give you some electricity.

I think it's important to point out that the particles detected by that observatory were gamma rays - not the original cosmic rays accelerated by the source. In the supernova remnant model of PeVatrons, high-energy protons obtain their energies through a phenomenon known as diffusive shock acceleration. As they leave the region in which they were accelerated, some collide with dust or gas, forming gamma rays of slightly lower energies. It's those gamma rays that were detected by the LHAASO group - and it's those gamma rays that would likely be best for us to exploit.

We can certainly generate electricity from gamma rays of certain energies; as I wrote in another answer, physicists were able to create semiconductor cells not unlike solar panels that generated electricity from some flux of gamma rays (Hashizume et al. 2011). The big issue is that these cells aren't very efficient, converting only ~1% of the gamma ray energy to electricity, compared to the 25% efficiency that we see in many typical high-quality solar panels. This means that even if a 1 PeV cosmic ray transfers its entire energy into gamma rays, and even if those are all received by this gamma ray solar cell, you'll only get 0.1 TeV of energy. WolframAlpha describes that as 10% of the kinetic energy of a flying mosquito. Bear in mind that the PeV gamma ray flux from any PeVatron is nowhere near the flux of, say, the Sun at visible wavelengths. After all, it's not like LHAASO was bombarded with gamma rays. They had a single detection.

On the plus side, gamma ray semiconductor cells are also going to receive lower-energy photons, which is one saving grace of this scenario. Gamma ray sources don't just emit photons at one energy, but across a spectrum, as you might expect - in the case of PeVatrons, not all of the accelerated protons have the same amount of energy. There are far more protons - and by extension gamma rays - with lower energies. So you're going to get a few PeV-level photons every once in a while and a lot more photons in the ~0.1-1 TeV range. Those low-energy photons should actually dominate the energy flux.

As a side note, I know you said you want PeVatrons to be your energy source, but just bear in mind that they aren't exceedingly bright. For example, as seen from Earth, SNR G106.3+02.7, the likely source of the LHAASO gamma rays, has a gamma ray brightness of only 5% that of the Crab Nebula, the brightest gamma ray source in the sky. Add onto that the fact that the Crab is twice as far away as SNR G106.3+02.7, and the inverse square law tells us that the PeVatron is actually intrinsically two orders of magnitude dimmer than the Crab - it's only 1% as luminous in gamma rays at 1 TeV and up. Albert et al. 2020 and Hillas et al. 1998 have spectra of the sources if you want a more detailed comparison; you can see that the flux from the Crab is an order of magnitude higher at 10 TeV, and much greater than that at lower energies. So if we're truly being realistic, considering pointing your gamma ray cells at a brighter source when possible.

  • $\begingroup$ Interesting. I was hoping for an energy source for a ship far from any star, where solar power was simply not an option. The idea was to build a facility that greatly increase the production of these particles, enhancing the process of howsoever they are created, and focus then in a tight beam, to permanently power a ship in the middle of 'no-where'. A souped-up laser beam on steroids type of thing. I am actually after the particles themselves, not the gamma particles, since they obviously exist even if not directly detected. $\endgroup$ May 31, 2021 at 1:53


Photodisintegration... is a nuclear process in which an atomic nucleus absorbs a high-energy gamma ray, enters an excited state, and immediately decays by emitting a subatomic particle. The incoming gamma ray effectively knocks one or more neutrons, protons, or an alpha particle out of the nucleus.

Photodisintegration is endothermic (energy absorbing) for atomic nuclei lighter than iron and sometimes exothermic (energy releasing) for atomic nuclei heavier than iron.

For spacecraft, a photodisintegration engine serves two purposes. Exothermic fission of heavy elements makes energy to power the ship which is like any fission reactor that makes energy.

Waste heat is a huge problem with spacecraft because traditionally the only way to lose waste heat is to radiate it into space. The catalysis of endothermic fission of light elements by photodisintegration can consume heat, cooling the ship. Photodisintegration plays this role in some dying stars.

As the star reaches the end of its life, it reaches temperatures and pressures where photodisintegration's energy-absorbing effects temporarily reduce pressure and temperature within the star's core. This causes the core to start to collapse as energy is taken away by photodisintegration...

I was thinking about how it was lame to have to bring uranium along. Is there not some way to use the high PeV particles to make fission fuel? I think there is. Consider these super energetic particles. Why are they so energetic? It is not because they are so fast because lots of cosmic rays travel nearly at the speed of light. It must be because they are both very fast and massive.


There is evidence that these highest-energy cosmic rays might be iron nuclei, rather than the protons that make up most cosmic rays

Slamming an iron nucleus moving at near the speed of light into another heavy particle is how superheavy elements are made with particle accelerators, which is what your PeV accelerator is!. Your particle generator makes its own fission fuel in this way, the energy of the particle being consumed in fusion of the two heavy nuclei to make uranium, plutonium and other elements more massive than iron.

I will add that the fabulous energy of the PeV accelerator also allows new undiscovered superheavy elements to be synthesized. These include willkium and awesomium, which I have alloyed together and used to make this electric guitar.

  • $\begingroup$ An elegant solution. I will definitely have to research it. Some particles used for energy, others to cool the ship, depending on what material they strike. It begs the question, however, that instead of reaction mass, do you end up consuming 'fission' mass? Can you use fusion to undo the process? $\endgroup$ May 31, 2021 at 1:46
  • $\begingroup$ @JustinThymetheSecond - fusing heavy elements requires so much energy as to be wildly impractical. All the heavy elements were forged in supernovae, because that's the energy levels required. $\endgroup$
    – jdunlop
    May 31, 2021 at 14:09
  • $\begingroup$ @jdunlop Yet here we are developing fusion reactors on Earth. Yet we are hoping that they will be exothermic. $\endgroup$ May 31, 2021 at 15:39
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    $\begingroup$ I rather like Will's second idea, partly because it does happen in nature with lighter cosmic rays - it's called cosmic ray spallation. Not sure how much research has been done on spallation due to more massive atoms, but it's certainly quite possible. $\endgroup$
    – HDE 226868
    Jun 1, 2021 at 2:03
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    $\begingroup$ @JustinThymetheSecond - no. Fissionable elements' decay chains have them wind up at lead. But you really need to read up on fission and fusion, as uranium can't be used for nuclear fusion, and with high-powered gamma rays, you don't need a reactor, because you're fissioning heavy elements for energy without a critical mass. $\endgroup$
    – jdunlop
    Jun 1, 2021 at 14:32

As has been said, the energy density simply isn't there. However, frameshift:

The Bussard ramjet shows up now and then in science fiction. It unfortunately has a theoretical speed limit of 12% of lightspeed and in practice the limit is almost certainly much lower as that assumes you can somehow build a fusion reactor that works on the interstellar medium concentrated and flowing through it at 12% of lightspeed.

However, lets build a different kind of ship. You have some handwavium power source and these super accelerators on your ship--you gather up the interstellar medium, feed it into the accelerators and use that as your "rocket". Low acceleration but your speed is limited only by time and whatever your power source needs.

  • $\begingroup$ The idea is that this civilization is able to increase the energy density of the flow sufficiently by harnessing these sources like we harness rivers by building dams. $\endgroup$ May 31, 2021 at 13:40

I thought of two approaches a black body engine. Imagine a sphere of perfect blackness placed behind a perfect white body surface. As you heat up your engine using the high energy particle fired from earth, it heats up and at sufficient heat it starts to emit the EM radiation from one side of its body (the back side radiation is reflected from the white body surface). Energy radiated in one direction will then act as a sort of a propellant as E=hf=0.5mv^2.

Alternatively your idea of solar panels is a good one. Your ship is collecting spare particles as it floats through space. You use the PN junction specifically designed for high energy photon absorption. You then take whatever ions you collected on your interstellar journey accelerate it using the energy from PN junction and fire it backwards.


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