Abstract
We review progress to date on analysis of the 1 million second Chandra Very Large Project (VLP)observation of the Cassiopeia A supernova remnant. We explore the possibility that Casexploded into a ``bubble''. The red supergiant wind into which its blast wave is currently expanding, was possibly followed by a short period of fast tenuous Wolf-Rayet wind prior to explosion, leaving a low density region at the center, surrounded by higher density red supergiant wind. We also review the current state of hard X-ray observations and determination of the mass of 44Ti thought to have been ejected in the explosion, with a view to the constraints this places on the nature of the explosion itself, and where in the remnant 44Ti decay products are likely to be found.
