Space Shuttle
The Space Shuttle was a spacecraft operated by NASA as part of the Space Shuttle program. Its official program name was Space Transportation System (STS), taken from its original designation as the Orbital Vehicle 103 (OV-103). The first of four operational orbiters built, Columbia entered service in 1981 and completed 27 missions before disintegrating during reentry on February 1, 2003. Challenger, OV-099, also delivered successfully on its maiden flight on April 4, 1983; it carried out nine missions until it exploded shortly after liftoff on January 28, 1986. Following an extensive investigation and modifications to prevent further disasters of this type, Endeavour was ready for launch in May 1992. It flew 25 times before being retired in 2011. Discovery became the third operational orbiter in December 1984 and made 39 flights before being retired in March 2011. Atlantis was the fourth and final shuttle built; its maiden voyage took place in October 1985. During STS-132 mission flown on May 11–24 2010 it became the oldest operational spacecraft at that time having surpassed Columbia’s record by nearly 9 years. It had previously set several other records including those for longest single spaceflight by an orbiter (STS-123 at 17 days 15 hours) and most total time spent docked to ISS by any vehicle. Upon completion of STS-135 mission flown July 8–21 2011, Atlantis had logged a cumulative total of 307 days 8 hours 19 minutes 53 seconds—just over one year—in space over 33 flights since 1985. All together there have been 135 shuttle launches, two were test launches without crews aboard: Enterprise which flew free air drop tests prior to Columbia’s first orbital flight, and Challenger which broke apart 73 seconds into STS 51-L with loss of all seven crew members aboard that day. Of these 135 launches 133 were successful resulting in a 98% success rate including 2 partial losses due largely to weather effects that prevented planned landings following both STS 107 and STS 121 respectively. There were also two catastrophic failures resulting in loss of crews: Challenger which broke apart 73 seconds into her tenth flight STS 51-L, and Columbia which disintegrated 16 minutes prior to scheduled landing while returning from her twenty eighth mission STS 107 due to damage sustained during ascent from foam debris striking her left wing. One launch attempt resulted not only in scrubbing but destruction when high winds damaged Enterprise’s external tank while still attached at Kennedy Space Center LC39A prior to planned rollout for STSS 010/011 point TO point aborts test series – thus never reaching orbit nor carrying any astronauts or even payloads intended for them!+ The three remaining shuttles were each decommissioned upon completion of their final missions – Discovery on March 9 2011, Atlantis on July 21 2011,and Endeavour shown here rolled out from OPF bay 3 for SSPTS move late August 2012 – officially retired September 20 2012 after flying 25 times covering 122 million miles (196 million km) over 299 day 13 hour 18 minute careers.,,,,, At least one more will be preserved as museum displays per requirements specified within their retirement agreements with NASA however their final locations have not yet been determined as this is written early 2013..
All four shuttles were designed for reuse with minimal refurbishment between flights allowing each one to fly an average 100 times over their estimated 30 year lifespan though some sources estimate up 50% more depending upon maintenance schedules & techniques employed plus actual usage rates & requirements versus what was originally projected back when they were new.. However despite best efforts & intentions no reusable system is perfect & things do eventually wear out or break so that number has proven somewhat optimistic given repairs often take longer than expected thereby eating into potential flight opportunities. Also spares become increasingly difficult -& expensive! -to find or fabricate as time goes by thereby limiting his flexibility should something unexpected happen.. As such once decision was made postColumbia disaster focus shifted towards finishing assembly International Space Station then retiring shuttles per earlier mentioned agreement effective end FY2011 leaving only Soyuz & Progress vehicles capable rendezvous/docking plus Russian built ATV supply ship currently under construction Europe able reach ISS should need arise although latter unlikely enter service before mid late 2015 given ongoing problems getting components delivered timely fashion..+
In addition devoting significant amount resources towards continuing development SpaceX Dragon cargo craft revealed major deficiencies design manifested themselves during COTS Demo Flight 1 launched Falcon 9 rocket June 4 2010 just shy 3 months behind schedule. Though cause initial delay related mostly engine component issues SpaceX team quickly identified problem areas needing improvement then implemented changes necessary ensure success subsequent flights.. As result second demonstration mission accomplished all primary objectives set forth agreement signed September 2008 between company & NASA Ames Research Center Moffett Field California enabling move forward Commercial Orbital Transportation Services program now known popularly simply commercial resupply services or CRS. Under terms CRS contract SpaceX must complete minimum 12 cargo transport missions ISS using Dragon spacecraft mounted atop Falcon 9 rocket deliver various supplies equipment requested NASA Science Mission Directorate helping offset gradual phasing out capability provided venerable space shuttle fleet whose last flight occurred July 8 21 2011 signifying end era reliable low cost reusable access space enjoyed United States since inception Apollo program early 1960s…