Last week the spaceship made its final journey from home base Kennedy Space Center to the Smithsonian in Washington, D.C. Strapped to the top of its faithful travel companion, one of the Boeing 747s that has carried it across the continent many times, the spectacular looking pair made one last trip together.
The last ferry flight has received a lot of press coverage, so let’s take a look at the un-sung hero instead: the Shuttle Carrier Aircraft (SCA).
There are two of those behemoths with the designations of NASA 905 and NASA 911 (their tail numbers) respectively. Both Jumbo Jets had been commercial airliners before NASA acquired them to be modified into shuttle carrier craft; 905 used to fly for American Airlines until 1974 and 911 was part of the Japan Airlines fleet until 1990. In order to be retrofitted to carry a large spacecraft on their backs both aircraft were sent back to Boeing where the required modifications were carried out.
And there was a lot to be done! You can’t just stick an orbiter on top of a plane and expect it all to work. The average airplane fuselage is not designed to carry heavy loads on its back, and the orbiters aren’t exactly lightweight. Here’s what had to be done.
Three external struts with matching interior structural strengthening needed to be installed on the top of the fuselage — this is where the orbiter is attached. They also had to add two additional vertical stabilizers, one on each end of the standard horizontal stabilizer near the tail fin of the plane, to enhance stability during flight. All interior furnishings and equipment aft of the forward No. 1 doors had to be removed, and while the orbiters were still in service there was also a large amount of instrumentation used by SCA flight crews and engineers to monitor orbiter electrical loads during the ferry flights and also during pre- and post-ferry flight operations. The orbiters couldn’t just be switched off like a light, so the health of the space plane had to be constantly checked.
As complicated as the getup is it took only four crewmembers to make a ferry flight with the orbiter attached. And the orbiter itself also needed adjustments to survive the flight intact. Most noticeable is the large cone-like structure attached to the main engines at the rear of the orbiter. This cone improves the streamlining of the orbiter and allows for a smoother, less turbulent flight.
The 911 made its final ferry flight in February, the 905 has one more left: carrying Endeavour to Los Angeles in the Fall. Then both aircraft will be turned over to NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) program, carrying telescopes during their flights.
It’s a tough time for those pilots and flight engineers as well, since they have accompanied all the orbiters across the country for many years. But it’s not over, of course, because now we can all have a chance to see one of the orbiters up close in person in a museum where they’ll be carefully preserved for many generations to come.
Learn more about the two carrier aircraft from the official NASA fact sheet at www.nasa.gov/centers/dryden/pdf/355514main_FS-013_DFRC.pdf