In 15 years of data taking the Pierre Auger Observatory has observed no events beyond 10 11.3 GeV. This null result translates into an upper bound on the flux of ultrahigh-energy cosmic rays implying J(> 10 11.3 GeV) < 3.6 × 10 −5 km −2 sr −1 yr −1 , at the 90%C.L. We interpret this bound as a constraint on extreme-energy photons originating in the decay super-heavy dark matter (SHDM) particles clustered in the Galactic halo. Armed with this constraint we derive the strongest lower limit on the lifetime of hadronically decaying SHDM particles with masses in the range, 10 14 M X /GeV 10 16 . We also explore the capability of future NASA's POEMMA mission to search for SHDM signals.2 Investigations in String Theory have applied a statistical approach to the enormous "landscape" of vacua present in the theory [37]. Remarkably, these huge number of metastable vacua, O(10 500 ), can also accommodate the more severe fine-tuning required to characterize the SM with a small cosmological constant [40,41].