Mission Background
The mission was originally scheduled to be flown by Columbia; STS-118 would have marked that orbiter's 29th flight and its first visit to the International Space Station. However, the Space Shuttle Columbia disaster altered the planned flight schedules, and the mission was rescheduled for Endeavour. STS-118 served as Endeavour's return to flight after a planned orbiter re-fit and maintenance period that resulted in over 200 modifications to the orbiter.
One of the most important modifications that debuted during STS-118 is an upgraded power-distribution module, the Station-Shuttle Power Transfer System (SSPTS). SSPTS allows Endeavour to tap into the ISS power supply, converting up to eight kilowatts of electrical power from 120-volts direct-current (120VDC) ISS main voltage to the 28VDC system used by the orbiter. SSPTS was outfitted to the ISS Pressurized Mating Adapter-2 (PMA2) during STS-116. These upgrades will allow orbiters to remain docked at the station for an additional three to four mission days by saving cryogenic liquid hydrogen and oxygen needed to run the fuel cells which generate electricity aboard the orbiter; oxygen and hydrogen tank capacity is a major factor limiting the duration of orbiter free flights. Other systems debuting on this flight were a three-string GPS system, which replaces the three Tactical Air Navigation-units, used to guide the shuttle and calculate its position during reentry and landing and the new Advanced Health Management System which keeps an eye on the three main engines (SSMEs) during liftoff and will shut them down before any catastrophic damage might develop. (All SSMEs had their own computers to regulate, monitor, and shut them down in case of trouble; the new system extends and improves the monitoring capability for increased safety.) Endeavour also received several systems that the other orbiters had already been equipped with, such as a glass cockpit, improved wing leading-edge sensors and the OBSS.
STS-118 included mission specialist Barbara Morgan, the first Mission Specialist Educator. Morgan trained as the backup to Christa McAuliffe, NASA's Teacher in Space candidate from 1985 to 1986. McAuliffe was killed in the space shuttle Challenger accident on 28 January 1986. While McAuliffe and Morgan were classified as spaceflight participants and not as mission specialists in 1986, after the Teacher in Space Project was canceled, Morgan assumed the duties of Teacher in Space Designee and continued to work with NASA’s Education Division until her selection as NASA's first Mission Specialist Educator in 1998. Morgan completed two years of training and evaluation and began official duties in 2000. An Educator Astronaut is a fully trained astronaut who performs all the same duties that a regular astronaut does. Morgan became the first Mission Specialist Educator in space on STS-118, and will share what she learned from the experience with students during and after her flight.
| “ | Whether you’re teaching school, or whether you’re training as an astronaut, you put all you can into it, and get the most out of it. – Barbara Morgan | ” |
The mission marked:
- 150th manned US space launch
- 119th Space Shuttle flight
- 22nd International Space Station assembly mission
- 20th flight of Endeavour
- 94th Post-Challenger mission
- 6th Post-Columbia mission
- First flight with SSPTS
Read more about this topic: STS-118
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