The space shuttle has been around so long now that it's easy to forget one of its original claims to fame: it's a spacecraft that can also fly in the atmosphere like an airplane. That's only in its unpowered descent back to Earth, though.
The shuttle does require help getting off the ground. It rides a rocket when it's heading into outer space. And when it needs to make an aerial transit here in the earthly realm, it relies on the Shuttle Carrier Aircraft.
Actually, there are two of the shuttle-toting aircraft, both of them modified Boeing 747 jumbo jets that once served as commercial carriers. Here, in September 2009 following a mission to the International Space Station, one of the jets ferries the shuttle Discovery--which just yesterday lifted off on its final mission--from its landing strip at Edwards Air Force Base in California back to the Kennedy Space Center in Florida.
Along with the struts that attach a shuttle to the 747, another key modification to the jumbo jet is the addition of a pair of rectangular vertical stabilizers to the tail wings (aka horizontal stabilizers). At the aft end of the shuttle, meanwhile, the rocket exhausts are hidden by a streamlined cover meant to reduce turbulence. Seen here from above is the shuttle Columbia in March 2001.
The space shuttles measure 57 feet tall and 122 feet long, with a wingspan of 78 feet. The Shuttle Carrier Aircraft, by contrast, is 63 feet tall and 232 feet long, with a wingspan of 196 feet.
The typical cruising speed for the Shuttle Carrier Aircraft is about 250 knots, according to NASA, and the typical cruising altitude with the spacecraft attached is about 13,000 to 15,000 feet, with a range of roughly 1,000 nautical miles.
The first of NASA's two Shuttle Carrier Aircraft, NASA 905, starts an early morning ascent in December 1990 with Columbia on its back. The space agency acquired the jet from American Airlines in 1974 as it progressed toward the first test flights of a space shuttle prototype. (The second aircraft, NASA 911, was acquired from Japan Airlines in 1989 and delivered to the space agency in November 1990.) The Columbia was the debut member of NASA's orbiter fleet, making the first shuttle flight into orbit in April 1981.
This is the cockpit of one of the shuttle carrier 747s, seen in August 2005.
Flying the tandem arrangement is no easy feat; extra attention, for instance, has to be paid during takeoff and in-flight turns. "It's obvious [the orbiter] is up there, because there's a constant rumble that you can feel because of the wake of the orbiter hitting the vertical stabilizer of the 747," SCA pilot Gordon Fullerton said in a NASA article from 2005. But otherwise, he said, "it handles remarkably the same" as an unencumbered 747.
Even with a stripped-down interior, a Shuttle Carrier Aircraft weighs in excess of 250,000 or even 300,000 pounds, while the shuttle that it's toting can weigh upward of 176,000 pounds. That payload means the SCA can burn 40,000 gallons of fuel per hour, double what it expends when unburdened.
"It's brute force that keeps us flying," Larry LaRose, an SCA flight engineer, said in the 2005 NASA article. "When we're carrying an orbiter, we have to use twice the power and a lot more fuel to maintain flight."
How does NASA get the shuttle on and off the 747? It uses a structure called the Shuttle Mate-Demate Device. Here, the shuttle Endeavour rides the carrier aircraft to the MDD at Kennedy Space Center in December 2008.
A cantilevered substructure is used to control the lifting and lowering of the shuttle. Three hoists do the hard work, two attached to the aft portion of the lift beam and one to the forward portion. Their combined lifting capacity is 240,000 pounds (120 tons). This June 2009 image from the Kennedy Space Center shows the shuttle Atlantis.
Here we see the Discovery ensconced in the Kennedy Space Center MDD in August 2005. After the shuttle is lifted off the 747 and the aircraft is rolled away, the shuttle is lowered to the ground to be towed to the Orbiter Processing Facility for inspection, testing, and refurbishing. (Or vice versa: the MDD at Edwards AFB is used to lift the shuttle onto the 747 before the flight to Florida.)
This aerial shot from September 2000 gives an overview of the Shuttle Landing Facility at the Kennedy Space Center. The Mate-Demate Device is at right. (Those aren't Shuttle Carrier Aircraft on the tarmac; rather, they're Grumman Gulfstream 2 aircraft that serve as shuttle trainers; their cockpits were modified to resemble those of the actual shuttles.)
It's hard to resist a gratuitous celebrity photo, so we digress for a moment with this April 1981 snapshot of Clint Eastwood. In the background is the Mate-Demate Device at Edwards AFB, enveloping the shuttle Columbia, which had just returned from the first-ever shuttle flight into orbit. (Standing with him is Ike Gillam, the director of NASA's Dryden Flight Research Center at the time.)
If you'll bear with us, though, there is a tenuous connection between star and spacecraft. Nearly 20 years later, Eastwood directed and starred in the adventure movie "Space Cowboys," a story in which aging astronauts fly a mission in a space shuttle.
Before the initial Shuttle Carrier Aircraft settled into its route of ferrying the orbiters across the country, it first helped demonstrate that the shuttle could fly, period. In a series of test flights in 1977, the prototype shuttle Enterprise went through captive ground and flight testing attached to the 747, then eventually made five free flights--this is one of them--between August and October of that year.
Updated:Caption:Jon SkillingsPhoto:NASA Dryden Flight Research Center (NASA-DFRC)
Test pilots in 1977
The forward windows of the Enterprise show flight commander Joe Engle (right) and pilot Richard Truly in the shuttle's cockpit in September 1977, as the shuttle sits atop its 747 in the Mate-Demate Device ahead of takeoff.
In December 2010, for the first time in its more than three decades of service with NASA, the Shuttle Carrier Aircraft carried something other than a space shuttle. The tiny aircraft riding the SCA on this occasion was the Boeing Phantom Ray, a prototype unmanned aircraft being ferried from Boeing's Phantom Works facilities in St. Louis to the Dryden Flight Research Center in California.