Cosmic Ray Update: New Results from the Moon | Hacker News Reader

Cosmic Ray Update: New Results from the Moon

spaceweatherarchive.com

55 pointsthrowaway362723 comments

As a layperson, I found this article about protecting spaceships from cosmic rays, from many years ago, to be very informative. I had seen the interview with Eugene Parker from the BBC "The Planets" not long before finding this article, so I was quite excited to find something written by him!

https://www.dartmouth.edu/~sshepherd/research/Shielding/docs...

“We can’t stop the highest energy cosmic rays, however. They penetrate the walls of any spacecraft.”

I was gonna say, we better bring spare parts with us, but imagine you just installed a new eyeball in your skull and it was full of dead pixels when you fired it up.

again, radiation absorbed dose from cosmic rays is different from that radiation of solar flares and coronal mass ejections. Cosmic radiation has been decreasing over time. Even a Mars mission at solar minimum would not expose the astronauts to significantly more radiation than they would have in orbit

http://www.srl.caltech.edu/ACE/ASC/DATA/bibliography/ICRC200...

Solar flare activity can be as hazardous to commercial air passengers

https://eos.org/research-spotlights/solar-flares-increase-ra...

In any event, we truly live in the goldilocks zone where a balance of cosmic factors enable us to enjoy life. Yet we continue to do our best to screw it all up because we can only think of one thing at a time. We should do more to increase the earth's ability to tolerate us.

Something not mentioned in the article: more shielding isn't always better when it comes to high energy cosmic rays. A single cosmic may pass straight through a person without interacting at all, but if you add shielding, that particle can create a shower of less energetic particles which can be ultimately more harmful.

Does it effect us on earth? Could it increase DNA and computer errors?

Cosmic rays do reach earth, and they can cause bit flips in memory. Generally any damage to human cells is repaired by cell reproduction. Cosmic rays are primarily protons so they get generally channeled by the magnetic field to one of the poles, and the air provides some shielding as well, but even with all of that you can build a cosmic ray detector[1] and get the occasional ping.

Generally it isn't something to worry about. Should we have a star nearby go super nova on us, or if a gamma ray burst occurred nearby (from a black hole eating a big chunk of matter for example) it would be more problematic.

[1] Cosmic rays are distinguished from "regular" solar flux by the energy of their particles (not all of them have higher energy, but the ones that do are much more likely to be of cosmic rather than solar origin). A simple cosmic ray detector can be constructed by shielding a cloud chamber such that shielding blocks any events below your desired cut off level. Detection events are then most likely cosmic rays.

IIRC most turn into muons or electron/positiron showers, depending on the incident angle. Recall a physics lab long ago playing with NaI scintillators and photomultipliers at 10kV to detect the muons from the showers.

Yeah, rather than reaching earth’s surface directly, it’s far more likely that a given cosmic ray will collide with molecules in the atmosphere, creating a particle shower [1].

Extremely high-energy cosmic rays are sometimes detected, however. The so-called “Oh-My-God particle“, detected in 1991, apparently carried as much energy as a baseball moving at 58 mph [2].

[1]: https://en.wikipedia.org/wiki/Particle_shower

[2]: https://en.m.wikipedia.org/wiki/Oh-My-God_particle

You are correct, the cosmic rays you see in a cloud chamber are typically muons (and its pretty easy to make one with stuff you can get at the drug store (or apothecary if you're outside the US :-)). If you want to see the higher energy ones then shielding helps.

On a more positive note, cosmic ray flux and the ensuing daughter products are used by geologists to date how long a particular rock has been buried or exposed.

https://en.m.wikipedia.org/wiki/Surface_exposure_dating

More or less, how often is “occasionally”? Can this be used as a source of randomness, like for example time as a Poisson?

> More or less, how often is “occasionally”? Cosmic ray fluxes vary depending on the energy of the photon you're talking about, but the number of events is, on a human scale, surprisingly large.

> Can this be used as a source of randomness, like for example time as a Poisson?

Yes. Although from an electronics point of view, lower energy photons are _much_ easier to deal with. That's how random.org started -- https://www.random.org/history/

A good example of "bad things" happening would be Quantas Flight 72 [1], an event in 2008 in which an Airbus A320 made a series of uncommanded movements, because of a particularly strange design bug in one of its flight computers, the air reference data unit one. Despite being repeated in triplicate, a timing bug occasionally resulted in pitch down movements being voted on as the 'correct' thing to do. Unlike MCAS in the 737, these were _not_ repeated and ultimately the pilots were able to fly in 'alternate law', and land safely.

Subsequent investigations believe that a cosmic ray induced bit flip is the most likely explanation.

[1] https://en.wikipedia.org/wiki/Qantas_Flight_72

Try looking it up in search engines first:

https://en.wikipedia.org/wiki/Cosmic_ray#Effect_on_electroni...

https://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays...

Please don't be a jerk on this site. The threads are supposed to be conversations, and that question was just the sort of thing one asks in conversation.

https://news.ycombinator.com/newsguidelines.html

I’m pretty sure I have seen a cosmic ray flash a couple of times over the past 20 years, lying in bed with eyes closed. It’s a sudden, bright flash caused by a cosmic ray hitting the optic nerve. I read that Astronauts get them frequently, causing sleep difficulties.

Citation https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena

We've evolved with this rate of radiation and are adapted to it. It's even possible that we need it for something.

Yes. Both.

My son was most likely hit by a cosmic ray in the early stages of development in the womb. It will have effected only a small number of cells (maybe even a single one) but the error replicated and caused a malformation in his heart.

Ok, so cosmic rays represent 20x the radiation dose of solar flares. That data is meaningless without relating the values to actual health impacts on human beings, which the authors don't even attempt to do. Would a year in space represent a 10% lifetime increase in the risk of cancer? I have no idea and neither do these authors. This is childish alarmism.

From a risk management perspective, with the little that we do know, an increase in cosmic ray dose is indeed a concern. That we don't know the exact % isn't all that relevant, we know enough to know the baseline dosage was already substantial enough, that any increase is not negligible.

I'm no radiation expert, but I have referred to https://xkcd.com/radiation/ a few times.

The symptoms they describe of a solar flare would, according to the chart, put it at around 400 - 4000 mSv.

I'm not sure it's correct to say that cosmic rays are 20x worse than solar flares since they're over a much longer period of time and the effects of radiation are related to both the intensity and duration of exposure.

Perhaps the authors of the paper made the assumption that the reader would already be familiar with the effects of ionizing radiation on humans?

For example, this presentation by NASA (https://ccmc.gsfc.nasa.gov/RoR_WWW/SWREDI/2013/Evans-SWREDIB...) on Solar Energetic Particles (or SEPs) relates how one can translate from pfu (proton flux units which are used in the article linked) and biological effects as part of the solar storm intensity scale (slide 15).

Perhaps if someone was already familiar with the NASA research into SEPs, they would read this paper/article and say "Hmm, here is some evidence that Cosmic rays are not something that can be assumed to be negligible when evaluating radiation exposure risk."

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