CAPTAIN MICHAEL L. COATS - TYPED LETTER SIGNED 01/28/1980 - HFSID 48389

MICHAEL COATS
He signs a typed letter containing his detailed explanation of the Space Shuttle's navigation systems.
Typed Letter signed: "Michael L. Coats", 1 page, 8½x11. Johnson Space Center, Houston, Texas, 1980 January 28. On NASA letterhead to Dennis Cooper, Olympia, Washington. In full: "The Space Shuttle Orbiter uses three basic types of navigation equipment: inertial navigation, TACAN, and Microwave Landing System (MLS). Briefly, during launch, on orbit, and during most of the entry portion of a Shuttle flight, we use three inertial measurement units (IMUs), similar to the inertial navigation sets used by most jumbo jets, to determine our position. We can update the IMU position vectors by means of star sighting alignments and, if necessary, by ground tracking systems. We have five IBM General Purpose Computers (GPCs) to monitor and update the IMUs and actually calculate position. During the re-entry into the earth's atmosphere, we start to pick up TACAN stations as we pass 80,000 feet. We can pick up most stations up to 300 nmi at that altitude. We have three TACAN sets, and the GPCs use TACAN information to update our inertial navigation. Our final approach uses MLS, which is essentially the same as an ILS. Our final approach starts at 12,000 feet on a 20º glide slope, about 6 nmi from the runway, and continues even during rollout. The hardest part may be navigating on two legs after a week or so in space - no GPCs to help out. That's a very brief and simplified description of the navigation system on the Space Shuttle. If you need or want more detailed information, let me know. Keep 'em safe. Sincerely". As a US Navy pilot, Michael Coats flew 315 combat missions in Southeast Asia (1970-1972). He was a test pilot before entering the astronaut corps in 1979. Coats traveled into space aboard the Orbiter Discovery 3 times: on its maiden flight in 1984, and on addition missions (as spacecraft commander) in 1989 and 1991. In December 2005, Coats was named Director of the Johnson Space Center. Fine condition.