Actually this “fatwa” makes some sense. Whoever agrees to a one way trip to a barren planet, however unique and exciting,is in essence agreeing to forfeit his or her life .Philosophically it would seem this is being done not for unique scientific knowledge but essentially as a self gratifying act. Ethically self gratifying destructive acts are immoral .However if the sacrifice can be shown to benefit others in a tangible, real sense, it may be ethical.
The muzzies don’t seem to have a problem with forfeiting their lives for whatever insane reason du jour.