The military is making its mark on the fourth flight of Columbia. Consider, for instance, this mysterious order given by NASA mission control to the shuttle crew:
''You have a go to implement TTR (teleprinter) message 1-7 Charlie at the published time.'' That message, NASA officials say, relates to secret military experiments and will not be explained.
The Air Force's Paycom voice from California also speaks to the astronauts in prearranged codes: ''We would like you to go to panel L11 and watch the cover, and its open LED. If you see either the cover open or its open LED, we would then like you to select cover override on -- that's the up position -- and each one of these two times will consume a little bit less than seven minutes of your time.''