I seek from an SF writing point of view some much-needed clarification about solar flares, in particular their shortwave radiation components. So, given that x-rays, gammas and the like, propagate through space at light-speed - along with the rest of the electromagnetic spectrum - I take it then that this 'pure' radiation precedes, usually by a hefty margin, the charged particles aspect of a given solar flare (clumsily put, but I hope it makes sense). This in turn implies that there can be absolutely NO advance notice given about these incoming radiation emissions. . . yes? no? If the latter, then depending on the strength of these flare-based x-ray emissions (yet another conundrum for me!*) could they alone prove to be fatal for an unsuspecting astronaut, say, doing an EVA in interplanetary space? NB. Conscious as I am of having already raised this issue, I'm now presented with a plot scene in which an X-class solar flare engulfs Mars. This strike results in a high number of casulties among the (human) explorers, the primary cause here being radiation sickness. The crucial point for me, though, is this: the resulting death toll does not come from the flare's plasma cloud striking the surface of Mars; rather it's due to an earlier bombardment of intense x-ray emissions (the flare's advance stormtroopers, so to speak) for which there can be no prior warning given. Is this a halfway realistic proposition? * Yes, I'm aware that solar flares are measured by their x-ray strength; but the strong impression I get from the literature is that this high-end radiation and the flare's plasma cloud are all one thing, leastways in terms of their overall impact. Yet to me this simply isn't true. . . the various elements that comprise a solar flare are separated in time and space, often hugely so in view of the distances involved. At least that's how it seems to me. I'm just trying to get the science right, that's all.