Is the detection of optical activity in extraterrestrial samples a safe indicator for life?

Since Pasteur's times it has been accepted that optical activity and life are intimately correlated with each other, i.e. the one could not exist without the other. This argument logically allows the following speculation related to interplanetary exploration: detection of optical activity in an extraterrestrial sample would be the most straightforward proof of the existence of living matter outside the earth. On the other hand it has been shown that spontaneous production of optical activity can be achieved without the help of living matter, so that the close association of optical activity with life is not necessarily true. The paper discusses the possibilities which allow a proof of some sort of life on other planets by polarimetric methods.