Pratt & Whitney Rocketdyne today began testing its rocket engines in Mississippi and Florida. The tests, which will continue through Friday, are significant for the company because they combine both development and production engines, said Jim Maser, president of the Canoga Park-based rocket engine developer and manufacturer. “We’d like every week to be this way,” Maser said. Pratt & Whitney Rocketdyne engines have been used in four launches this year by the United Launch Alliance. The next launch using the company’s engines on an Atlas V rocket takes place in mid-June, Maser said. A development RS68A engine will be tested at the Stennis Space Center in Mississippi today. On Wednesday, a test of a J2X engine at Stennis will focus on a modified nozzle extension that dissipates heat that is generated by the engine. The seven-second test is the first of 16 taking place throughout the summer months, Maser said. An Atlas V rocket engine on Thursday will go through the standard acceptance test in West Palm Beach. Another J2X test takes place at Stennis on Friday; the goal is to push to the limits the gas generator and turbo machinery to see how they operate and meet engineering expectations, Maser said. Mark Madler