Timeline: ISS, U.S. Shuttle Program's Symbiotic Relationship

When Space Shuttle Endeavour roared off the launch pad one last time, it headed up for one more rendezvous with the International Space Station (ISS) before the venerable space-truck retires to museum status. The historic mission drew worldwide attention, and not just for the launch.

Arizona Congresswoman Gabrielle Giffords, wounded in the Tucson shooting tragedy Jan. 11, was able to attend the launch. Her husband, Mark Kelly, commands the flight. Husband and wife both worked to get her to Florida. Giffords is achieving a folk hero persona, fighting back admirably from her near-mortal wound.

The current Endeavour mission (STS-134) is going up to the ISS to bring service and maintenance parts and deliver yet another exciting manifestation of scientific curiosity: the Alpha Magnetic Spectrometer. Endeavor has a history with the ISS - she was the first shuttle to begin assembly work in orbit on the space station.

Following is a timeline of other historic interactions between the shuttle fleet and the International Space Station.

Dec. 4, 1998 - NASA launches Endeavour (STS-88) on a 12-day mission to bring components of the ISS together for the first time

The crew first docked with the U.S.-built Unity module, then rounded up the Russian-built Zarya control module and mated it to Unity. After that was accomplished, according to "Human Spaceflight" by Joseph A. Angelo, spacewalks were constructed to connect cabling and other components. After the successful connecting operations, astronauts and cosmonauts went into the modules, marking the first human occupation of the ISS.

Feb. 1, 2003 - Columbia disintegrates on re-entry, places future of ISS in question

While Columbia wasn't coming back from a mission to the ISS when it came apart upon re-entry, the loss of a shuttle put the continuation of the ISS program under stress. It would be July 26, 2005, before another shuttle flight. When cameras discovered a missing piece of protective foam from the skin of Discovery, the program went on hiatus again.

The next flight came July 4, 2006, when Discovery once again blasted into orbit. The shuttle delivered supplies to the ISS, but It would take until Sept. 9, 2006, for construction to resume on the space station. With the launch of Atlantis on a building mission, the ISS once again moved forward.

The Columbia disaster, Hubble Space Telescope, and the ISS as a safety refuge

After Columbia was lost while attempting to land in 2003, the scheduled servicing mission for the Hubble Space Telescope was initially canceled. According to CNN, astronaut safety was the main concern. Missions going up to the ISS could use the station as a lifeboat should damage occur that would prevent a shuttle from safe re-entry.

The Hubble, however, is in a higher orbit than ISS and a shuttle servicing it would have to return to Earth. If something went wrong, a shuttle could not reach and maintain a lower orbit, but would have to re-enter once it committed to doing so. Eventually, NASA changed plans and the servicing was conducted successfully. The next American spacecraft to reach the ISS may be commercial.

STS 135, scheduled for June 28, is last Space Shuttle mission, and it's going to the ISS

When shuttle Atlantis makes the final shuttle flight for the U.S. space program, it will be taking more supplies and parts up to the ISS. It's a fitting end to a symbiotic relationship. After Atlantis, the ISS will have to depend on Russian Soyuz capsules for crew transportation and unmanned Russian, European, and Japanese craft.