  Gamma Ray Bursts (GRBs) are intense narrowly-beamed flashes of gamma-rays of
cosmological origin. They are among the most scientifically interesting
astrophysical systems, and the riddle concerning their central engines and
emission mechanisms is one of the most complex and challenging problems of
astrophysics today. In this article we outline our petascale approach to the
GRB problem and discuss the computational toolkits and numerical codes that are
currently in use and that will be scaled up to run on emerging petaflop scale
computing platforms in the near future.
  Petascale computing will require additional ingredients over conventional
parallelism. We consider some of the challenges which will be caused by future
petascale architectures, and discuss our plans for the future development of
the Cactus framework and its applications to meet these challenges in order to
profit from these new architectures.
