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Does the radiation from a GRB have enough energy to move something as big but as light as a solar mirror off of its orbital path and destabilize it?

If it helps these mirrors are meant for terraforming several planets within our solar system, Venus and Mars respectively. I still need to do research on how big those would have to be but if that can give you guys some help in the numbers department then it's there for reference.

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    $\begingroup$ Then question has the hard-science tag. To get a hard-science answer you should really give us some details about the size, mass and position (orbit) of that mirror, could you edit those details in? $\endgroup$
    – Escaped dental patient.
    Commented Sep 15 at 14:13
  • $\begingroup$ This really depends on what the space mirror is orbiting. A gamma ray burst from an object many light years away will have so few photons that it wouldn't. $\endgroup$
    – David R
    Commented Sep 15 at 14:24
  • $\begingroup$ Can it? Yes... if the conditions are right $\endgroup$
    – Kilisi
    Commented Sep 16 at 3:26
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    $\begingroup$ In principle yes, but a burst close enough to affect a mirror’s orbit would have other much more major effects, like destroying most life on Earth. $\endgroup$
    – Mike Scott
    Commented Sep 17 at 6:20
  • $\begingroup$ Well that is actually the point. This GRB is what triggers my settings Post Apocalyptic Era by wiping out a good chunk of Humanity that's spreading out all across the Galaxy by this point in time. $\endgroup$
    – Altarious
    Commented Sep 17 at 10:51

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Extremely improbable, for the reasons given in the other answers --

IF

-- you want it to do it directly.

However, having the gamma ray burst do damage to the control system is much simpler because it is a matter of damage, not motion, and because the affected area is so much smaller. Then the damaged control system can knock the space mirror out of orbit.

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    $\begingroup$ Excellent point, gamma is not great for electronics. $\endgroup$
    – Escaped dental patient.
    Commented Sep 15 at 16:27
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    $\begingroup$ Ahh, that makes a lot more sense! Thank you!! $\endgroup$
    – Altarious
    Commented Sep 15 at 18:58
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Probably not. My reasoning is this:

  1. Mirrors have a reflection ratio of maybe 99%. Not too much - that means that 1% of the incoming energy is swallowed by the material and heats it.
  2. Gamma Ray Bursts are mostly gamma rays. Sometimes they have also a visible light component, but it is a minority.
  3. There is no known matter capable of reflecting gamma rays. We could say the reflection ratio of practically everything is practically 0 for gamma rays.
  4. If the mirror is thin, it will be transparent to gamma rays. Exactly how, that depends mostly in the proton number of its atoms (as far as I can remember, it depends roughly on the fourth or fifth power of its proton count - the result being that lead is practically black for gamma rays while aluminium is transparent).
  5. Swallowed photon energy is also transferred as an impulse based on the $P=\frac{E}{c}$ formula. That is also known as light pressure. That $c$ is very big, the speed of light. A surprising coincidence: it is exactly the same energy (and thus, destructive effect) as if no relativity existed, but instead tiny balls were being shot at the mirror at the speed of light.
  6. Gamma ray bursts are short. The longest of them exists maybe for a minute.

We need to consider

  • The energy swallowed by the mirrors in a short time,
  • The impulse given to these mirrors, and
  • The time until the mirrors evaporate.

I could calculate it, and I will do it on a challenging comment, but the practical reality is that the light pressure is very little. Thus, for light pressure to have a considerable effect requires a huge amount of light (gamma radiation).

If the GRB is close enough or strong enough, then the mirrors will evaporate or not shield at all. To have an astronomically meaningful effect, that would likely need a much longer exposure where the mirror can also cool from the back.

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  • $\begingroup$ Sounds good. One thing that pops into mind is the question of what accompanies GRBs, is there also an ejection of charged matter sufficient to be of concern? $\endgroup$
    – Escaped dental patient.
    Commented Sep 15 at 15:50
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    $\begingroup$ @Escapeddentalpatient. GRBs are produced by relativistic jets. However, the particle component will lag behind the gamma rays, if it's not blocked or scattered beyond recognition by the interstellar medium. $\endgroup$
    – Christopher James Huff
    Commented Sep 15 at 16:24
  • $\begingroup$ @Escapeddentalpatient. Probably yes. But they are coming slower as the photons, and the billions of light years is enough for them to disperse. Sometimes we experience particles with unthinkable energy: en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray $\endgroup$
    – Gray Sheep
    Commented Sep 15 at 16:40
  • $\begingroup$ Wow. Interesting wiki, glad I've read that now - in itself that's the basis for a plot-point and questions here. $\endgroup$
    – Escaped dental patient.
    Commented Sep 15 at 16:47
  • $\begingroup$ (1) and (3) seem to be at odds. Talking about reflection ratios of mirrors, then later saying that no materials are known to reflect gamma rays. I agree on the general idea, just that using both together doesn’t make so much sense to me. $\endgroup$
    – fyrepenguin
    Commented Sep 16 at 0:10
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It depends: gamma ray bursts are mostly made of gamma photons. From Wikipedia

Most of this energy is released in gamma rays, although some GRBs have extremely luminous optical counterparts as well.

a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime

Solar mirrors are not optimized for reflecting gamma rays, so a gamma ray burst which has low optical component would either pass through the mirror or get absorbed and damage it. The resulting vaporization of the mirror surface would probably have some effect on the attitude of the mirror and in the long term also perturbate its orbit, if enough of it remained.

If the optical component is significant, it is possible that also the orbit is affected by the mirror reflecting them, as the momentum associated with all those photons is decently sized.

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  • $\begingroup$ Oooooh, ok now that is cool. I didn't think about that and that actually makes it even better, if the mirrors are damaged then that'll mean that whatever functions they were preforming, in this case Terraforming several planets will be in jeopardy which is actually great for the story. $\endgroup$
    – Altarious
    Commented Sep 15 at 14:25
  • $\begingroup$ There is no known matter what could reflect gamma rays. Maybe neutron star material. Our current technology ends with a very costly, very ineffective reflexion of soft Roentgen. Above that, science stops. No one has even an idea, where to even start the research. $\endgroup$
    – Gray Sheep
    Commented Sep 15 at 15:51
  • $\begingroup$ ((If you had an idea, that could enable us to create million times faster chips. You would be billionaire already from the patent. It is one of the current edge researches of chemistry.)) $\endgroup$
    – Gray Sheep
    Commented Sep 15 at 15:58
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Simple test:

Space mirrors for energy redirection are thin. Very, very thin. Just about all the gamma energy is just going to go through. But they are set up to reflect most of the visible light hitting them.

If a tiny percent of the energy of the GRB can move it enough to knock it out of orbit then the energy of the GRB has to have a few extra zeroes on the energy level compared to the solar incident energy. At that point the loss of your mirror is small potatoes. (And I find myself strongly doubting that it could be knocked out of orbit without at least being melted.)

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  • $\begingroup$ This is the right answer. If the GRB imparts enough momentum to knock around a solar mirror, the Earth just melted $\endgroup$
    – thegreatemu
    Commented Sep 18 at 0:04
  • $\begingroup$ @thegreatemu The Earth is thick, it's not going to be melted. My memory is that most of that energy is going to be dumped in the atmosphere--I don't think you're going to want to be breathing that atmosphere. $\endgroup$
    – Loren Pechtel
    Commented Sep 18 at 16:00
  • $\begingroup$ fair enough, exaggeration on a science-based question is a bad idea. Definitely apocalypse scenario though. $\endgroup$
    – thegreatemu
    Commented Sep 18 at 16:57
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This really depends on how close the gamma-ray burst is, and on whether "vaporized" counts as "knocking out of orbit." From the Wikipedia article:

A GRB would be able to vaporize anything in its beams out to around 200 light-years.

If there's a GRB closer than that, not just the mirror but also Earth might be destroyed. So there is plenty of energy to vaporize anything you want!

But suppose you want to push the mirror out of orbit without vaporizing it. Here what matters is how much momentum can be imparted. As the name suggests, the GRB is mostly very high-energy photons - gamma rays. Gamma rays do not penetrate very deeply into solid materials; they will deposit most of their energy in the top few inches of the object. So, if the object is thicker than a few inches, the top layer of the object facing the GRB can rapidly vaporize, producing a reaction force (like a rocket engine) on the rest of the object, which could remain solid and not too damaged. This could be sufficient to push the mirror out of orbit mostly intact, provided the mirror is thicker than a few inches.

The effects would be similar to a nuclear weapon going off in space, which also deposits much of its energy as gamma rays. The GRB lasts a lot longer than the nuclear weapon detonation, but the end result should be similar. See this answer, which includes Python code to calculate the momentum change for a spaceship from its outer hull vaporizing due to incoming radiation.

A burst sufficient to de-orbit a satellite by partially vaporizing it would be very damaging to life on Earth, and would change the orbit of not just the mirror but all smaller objects throughout the solar system.

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Others have said, better than I can, "not likely." But the mirrors would probably serve to detect the GRB even if no one was looking for one. That would give your civilization an "uh-oh!" moment, if the burst were close enough that massive particles (coming well behind the gamma flash) could cause your civilization crash. Perhaps just enough time to throw up some hasty leaky shielding, hunker down and ride it out?

I thought of Anderson's "Day of Burning", which focuses on problems of nationalism in time of a System-scale crisis.

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