Digital Preservation deals with the long-term storage, access and maintenance of digital objects. Preservation experts are faced with an almost overwhelming variety of preservation actions and tools but, as individuals, lack the time and resources required to build the evidence base that an informed decision process requires. As one of the core developments of the Planets project, the Planets Testbed offers a scientific research environment to perform and document experiments for digital long term preservation. This paper provides an overview on the Planets Testbed and provides a case study demonstrating how the Testbed can be used to perform complex experiments using Planets preservation services, large datasets and the automated evaluation of results.