  Lifetimes of super-heavy (SH) nuclei are primarily governed by alpha decay
and spontaneous fission (SF). Here we study the competing decay modes of
even-even SH isotopes with 108 <= Z <= 126 and 148 <= N <= 188 using the
state-of-the-art self-consistent nuclear density functional theory framework
capable of describing the competition between nuclear attraction and
electrostatic repulsion. The collective mass tensor of the fissioning
superfluid nucleus is computed by means of the cranking approximation to the
adiabatic time-dependent Hartree-Fock-Bogoliubov approach. Along the path to
fission, our calculations allow for the simultaneous breaking of axial and
space inversion symmetries; this may result in lowering SF lifetimes by more
than seven orders of magnitude in some cases. We predict two competing SF
modes: reflection-symmetric and reflection-asymmetric.The shortest-lived SH
isotopes decay by SF; they are expected to lie in a narrow corridor formed by
$^{280}$Hs, $^{284}$Fl, and $^{284}_{118}$Uuo that separates the regions of SH
nuclei synthesized in "cold fusion" and "hot fusion" reactions. The region of
long-lived SH nuclei is expected to be centered on $^{294}$Ds with a total
half-life of ?1.5 days.
