In Buzz Aldrin's book Encounter with Tiber, he mentions that some of the Space Shuttle's fuel tanks actually made it to orbit. Did this actually happen, and if so, for how long did they stay in orbit, and what altitude did they achieve?
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asked May 10, 2014 at 15:33
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$\begingroup$ Related: Were Space Shuttle External Tanks recoverable and reusable? $\endgroup$– called2voyage ♦May 12, 2014 at 19:10
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1$\begingroup$ Technically, some of the tanks did make it to orbit - the OMS and RCS tanks built into the orbiters. $\endgroup$– VikkiFeb 24, 2019 at 4:42
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2 Answers
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Based on this description of the Space Shuttle flight profile, no external tank would ever have completed so much as a single orbit. An external tank would achieve essentially the same orbital apogee as the orbiter itself, but that is all. The shuttle fired its OMS engines to achieve an actual orbit AFTER tank separation. This means that the tank remained on a trajectory which would intersect (re-enter) the atmosphere with no chance of ever completing an orbit.
The only way an external tank could remain in orbit would be if it was left attached until after the orbiter had completed its OMS burns to establish an orbital trajectory. To do so would increase the mass to which the OMS engines must apply the required delta-V... by more than the vehicle's payload capacity. This would require reducing, or more likely eliminating the internal payload. The upshot being that a shuttle flight in which a tank is inserted into orbit (if it were even possible) would be a mission to insert a tank into orbit and almost certainly accomplish nothing else. See this question for a more comprehensive analysis.
Aldrin has apparently exercised a bit of creative license; the title you mention is after all, a work of fiction.
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$\begingroup$ It would have been an interesting mission, regardless. You have to wonder how much the extra weight would have added to the total fuel needed. $\endgroup$– user3323May 10, 2014 at 20:41
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2$\begingroup$ @doz An empty external tank weighs about a quarter the loaded weight of the Shuttle, so to a first approximation, it'll increase the fuel requirement by 25% or so. $\endgroup$– MarkMay 11, 2014 at 1:18
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$\begingroup$ @Mark which then in turn increases the mass by... which then increases the fuel... which then incr... $\endgroup$ Aug 12, 2018 at 21:24
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1$\begingroup$ @MagicOctopusUrn, not really. Check the rocket equation: for a fixed change in velocity, a linear increase in payload mass requires a linear increase in fuel mass. Think of it this way: if a rocket with
Xfuel can throw payloadYinto orbit, then two rockets each withXfuel can throw a total payload of2Yinto orbit. $\endgroup$– MarkOct 16, 2018 at 22:36
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There are generally speaking 2 conops to get into orbit with the Space Shuttle. The first one, and most commonly used, requires two thrusts post Main Engine CutOff (MECO) to achieve orbit. This one drops the ET in the Indian Ocean. The "Direct Insert" requires only one OMS maneuver, and the tank landed in the Pacific Ocean. So the External tank might technically have been in orbit briefly, but in a reentry orbit.
answered May 11, 2014 at 15:23
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1$\begingroup$ Mneh. If PeA is negative, this isn't like being in orbit. $\endgroup$ May 11, 2014 at 17:39
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$\begingroup$ It is like ballistic orbit, according to abyss.uoregon.edu/~js/space/lectures/lec05.html or ballistic trajectory astronomycast.com/2012/11/ep-277-orbit $\endgroup$– osgxMay 12, 2014 at 12:10
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4$\begingroup$ Eh, it's an orbit, just one that happens to intersect the Earth's surface :-) $\endgroup$– TristanMay 12, 2014 at 15:16
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1$\begingroup$ I was more thinking upper atmosphere, which would drag it down enough to hit the Earth pretty quickly. $\endgroup$– PearsonArtPhoto ♦May 12, 2014 at 15:17
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1$\begingroup$ Direct insertion was the most commonly used method of space shuttle orbital insertion. $\endgroup$– VikkiFeb 1, 2020 at 0:40