Actually the halo rings obliterates all sentient life down to the atomic level. It doesn't attack the nervous system only. It simply reduces humans and every other form of sentient life into gas and dust. So yea......I think that if, you take every single sentient being in the galaxy, they would weight a lot more than Mars and probably more than any terrestrial planet. And those shields are specifically made around certain outposts to keep the effects of the halo out I border to re-seed the Galaxy. So just any old shield won't do. It has to be made with the technology of halo on mind.