Editing Space Shuttle (section)

===External tank===
{{main|Space Shuttle external tank}}
[[File:External_Tank.jpg|right|thumb|The ET from [[STS-115]] after separation from the orbiter. The scorch mark near the front end of the tank is from the SRB separation motors.]]
The Space Shuttle external tank (ET) carried the propellant for the Space Shuttle Main Engines, and connected the orbiter vehicle with the solid rocket boosters. The ET was {{convert|153.8|ft|m|sigfig=2|abbr=on|order=flip}} tall and {{convert|27.6|ft|m|sigfig=2|abbr=on|order=flip}} in diameter, and contained separate tanks for liquid oxygen and liquid hydrogen. The liquid oxygen tank was housed in the nose of the ET, and was {{convert|49.3|ft|m|sigfig=2|abbr=on|order=flip}} tall. The liquid hydrogen tank comprised the bulk of the ET, and was {{convert|96.7|ft|m|sigfig=2|abbr=on|order=flip}} tall. The orbiter vehicle was attached to the ET at two umbilical plates, which contained five propellant and two electrical umbilicals, and forward and aft structural attachments. The exterior of the ET was covered in orange spray-on foam to allow it to survive the heat of ascent.{{r|jenkins|p=421–422}}

The ET provided propellant to the Space Shuttle Main Engines from liftoff until main engine cutoff. The ET separated from the orbiter vehicle 18 seconds after engine cutoff and could be triggered automatically or manually. At the time of separation, the orbiter vehicle retracted its umbilical plates, and the umbilical cords were sealed to prevent excess propellant from venting into the orbiter vehicle. After the bolts attached at the structural attachments were sheared, the ET separated from the orbiter vehicle. At the time of separation, gaseous oxygen was vented from the nose to cause the ET to tumble, ensuring that it would break up upon reentry. The ET was the only major component of the Space Shuttle system that was not reused, and it would travel along a ballistic trajectory into the Indian or Pacific Ocean.<ref name=jenkins />{{rp|422}}

For the first two missions, STS-1 and [[STS-2]], the ET was covered in {{convert|595|lb|kg|sigfig=2|abbr=on|order=flip}} of white fire-retardant latex paint to provide protection against damage from ultraviolet radiation. Further research determined that the orange foam itself was sufficiently protected, and the ET was no longer covered in latex paint beginning on STS-3.<ref name=jenkins2016 />{{rp|II-210}} A light-weight tank (LWT) was first flown on STS-6, which reduced tank weight by {{convert|10300|lb|kg|sigfig=2|abbr=on|order=flip}}. The LWT's weight was reduced by removing components from the hydrogen tank and reducing the thickness of some skin panels.<ref name=jenkins />{{rp|422}} In 1998, a super light-weight ET (SLWT) first flew on [[STS-91]]. The SLWT used the 2195 aluminum-lithium alloy, which was 40% stronger and 10% less dense than its predecessor, 2219 aluminum-lithium alloy. The SLWT weighed {{convert|7500|lb|kg|sigfig=2|abbr=on|order=flip}} less than the LWT, which allowed the Space Shuttle to deliver heavy elements to ISS's high inclination orbit.<ref name=jenkins />{{rp|423–424}}