Still observing the Earth after 25 years—22 beyond its three-year primary mission lifetime—Landsat 5 collects valuable scientific data daily. Some attribute the satellite's longevity to over-engineering. Others say it's a long run of good luck. Whatever the reason, no one who attended the satellite's March 1984 launch could have expected it would still be working today.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0