The final set of Space Shuttle Main Engines (SSMEs) ever to be installed on a space shuttle, had been attached onto Atlantis (OV-104) in preparation for the final Launch On Need (LON) mission, STS-335 in support of STS-134 to be flown by Endeavour (OV-105) in April 2011.
STS-335 had since just recently received approval and authorisation from the United States Congress to be converted to a full fledged final mission for the NASA Space Shuttle fleet, STS-135, scheduled to be flown with just four crew members pending a review of funds availability for the upcoming fiscal year.
I have to give Orion full credit for being that dedicated, its inspired me to be aware of the sky just a little bit more as I look for the milky way in Alice Springs next week. Got any heads up on what to look for when I'm there?