From the beginning of American spaceflight, missions were numbered sequentially. Mercury-Redstone 3 (Al Sheppard) followed Mercury-Redstone-1A (uncrewed) & Mercury-Redstone 2 (Ham the chimpanzee). Gemini 3 (Gus Grissom & John Young) was followed by Gemini IV (Jim McDivitt & Ed White), the Roman numerals continuing all the way through Gemini XII (Jim Lovell & Buzz Aldrin). After the Apollo 1 tragedy, there was no Apollo 2 or Apollo 3, but the uncrewed Apollo 4, Apollo 5, & Apollo 6 were followed by the manned Apollo 7 (Wally Schirra, Donn Eisele, & Walt Cunningham) all the way through Apollo 17 (Gene Cernan, Ron Evans, & Jack Schmitt).
The early Space Shuttle flights followed this pattern. The Space Shuttle was the only part of the ambitious Space Transportation System (S.T.S.) architecture to be built, & so flights were numbered S.T.S.-X: S.T.S.-1 was followed by S.T.S.-2, all the way through S.T.S.-9. But all that changed when S.T.S.-9 was not followed by "S.T.S.-10," but by S.T.S.-41-B. That's an exaggeration, not everything changed: the S.T.S. prefix remained. Let's unpack the new & different "41-B."
"41" is no longer a sequential number, but a code, telling us specific things about the flight. Though read as forty-one, the four & the one refer to different traits. "4" refers to 1984, not the calender year 1984 but N.A.S.A.'s fiscal year 1984. "B" is the sequential part of the code, indicating that S.T.S.-41-B was the second Space Shuttle flight of fiscal year 1984. N.A.S.A.'s fiscal year 1984 began in October 1983; so, under the new system, November-December 1983's S.T.S.-9 would have been designated "S.T.S.-41-A." The Space Shuttle was still flying in 1994 & 2004 (though grounded in that latter year in the aftermath of the Columbia tragedy); it is unknown how those years would have been represented in this scheme. Would 1994 missions have been S.T.S.-141-X & 2004 missions S.T.S.-241-X? Or S.T.S.-941-X & S.T.S. 041-X? We'll never know. The use of the alphabet for sequential designation would allow for up to twenty-six flights per year, A through Z. The highest number of Shuttle flights in a single year was nine, in 1985.
The second digit in "41" refers to the launch site. "1" indicates the Kennedy Space Center in Cape Canaveral, Florida. S.T.S.-41-B was thus the second Space Shuttle flight of fiscal year 1984, launched from K.S.C. But wait, weren't all Space Shuttle flights launched from K.S.C.? Yes, they were. But there weren't always planned to be. Throughout the 1970s, N.A.S.A. needed the support of the Department of Defense to secure the funding necessary to develop a spacecraft as advanced as the Space Shuttle Orbiter. D.O.D. requirements influenced the design of the Orbiter Vehicle, such as the size of the payload bay. Lots of interesting missions could be flown from Cape Canaveral, but certain military missions required higher inclination orbits than could realistically be achieved by launching from Florida. "2" would have indicated Space Launch Complex (S.L.C.-6, "Slick Six") at Vandenberg Air Force Base in Santa Barbara County, California. Vandenberg was an ideal location for launching missions into polar orbit, a useful orbit for many military applications. The inaugural launch from S.L.C.-6, S.T.S.-62-A, was planned for July 1986, but cancelled in the aftermath of the Challenger tragedy.
This peculiar mission designation system willl be with us for the rest of 1984, all of 1985, & into 1986, fifteen missions overall. Adding to the confusion, with the post-Challenger Return to Flight, Shuttle flights returned to sequential numbering, S.T.S.-26 in 1988 through S.T.S.-135 in 2011. So, having just explored S.T.S.-41-B & looking forward to S.T.S.-41-C, down the road, we also have an S.T.S.-41, S.T.S.-51, & S.T.S.-61 in our future.
No comments:
Post a Comment