Technicians at NASA’s Kennedy Space Center in Florida are preparing space shuttle Discovery before they install the shuttle’s three main engines next week. Some of the most efficient machines ever built, the reusable main engines operate during the launch phase to push the shuttle into orbit. They are removed and inspected after each flight. The shuttle’s S-band radio system is another focus for the technicians as they continue Discovery’s standard processing work for the STS-133 mission. The S-band system links the shuttle to the ground by relaying telemetry and other information through NASA’s Tracking and Data Relay System satellites. The satellite constellation allows almost-constant communications with shuttles without relying on an assortment of ground stations spread all over the globe. Workers also installed and connected Discovery’s drag chute Wednesday. That won’t be used until landing, when it helps slow the shuttle as it moves down the runway. As for the astronauts slated to take Discovery into space, they are going through rendezvous training in the fixed-based simulator at NASA’s Johnson Space Center in Houston. STS-133 is targeted for launch in September on a mission to take the Permanent Multipurpose Module, along with supplies and equipment, to the International Space Station.