27 February 2017

A 1964 Proposal for a Small Lifting-Body Shuttle with "Staged Reentry"

Image credit: NASA
A lifting body is an aircraft that relies for lift on the shape of its fuselage, not on protruding wings. Many early lifting bodies were triangular as viewed from above and "tubby" as viewed from the side. The latter characteristic earned some of them the sobriquet "flying bathtubs."

Theoretical work on lifting bodies began in the United States in the 1950s at National Advisory Committee for Aeronautics (NACA) laboratories. Early lifting bodies took the form of horizontal half-cones with rounded noses and flat tops. They were viewed mainly as steerable reentry bodies for nuclear warheads launched on Intercontinental Ballistic Missiles. By the end of the 1950s decade, however, as the 1958 Space Act transformed NACA into NASA and transferred to it most Department of Defense space facilities and projects, some engineers began to propose that lifting bodies serve as piloted reentry vehicles.

NASA opted to launch its astronauts in conical capsules rather than lifting bodies, but the lifting-body concept was by no means abandoned. In fact, it became a common element of U.S. space planning. In 1961, for example, both The Martin Company and the Convair Division of General Dynamics gave their proposed Earth-orbital/circumlunar Apollo spacecraft design lifting-body Command Modules.

Cutaway view of The Martin Company's lifting-body Apollo Command Module with portions of adjoining components visible (left - the Launch Escape Propulsion System; right - housing for the tunnel leading to the the Mission Module). This Command Module configuration, which Martin called Model 410, measured 12.5 feet long from its dome-shaped nose to its flat aft bulkhead and 12.5 feet across the widest part of its flat top. Image credit: The Martin Company/NASA
The same year, the U.S. Air Force, as part of its LUNEX study, proposed a piloted moonship comprising a landing stage with a lifting body stacked on top. In 1963, Philco Aeronutronic designed a lifting-body piloted Mars lander on contract to NASA's Manned Spacecraft Center in Houston.

Also in 1963, engineers and test pilots at the NASA Flight Research Center (FRC - later Dryden FRC; now Armstrong FRC) at Edwards Air Force Base (AFB), California, began piloted test flights of the M2-F1 lifting body (image at top of post). The lightweight M2-F1, a glider with a tubular steel frame and a mahogany plywood skin, was towed aloft a total of 77 times between March 1963 and August 1966 using a souped-up Pontiac Catalina convertible or a Douglas C-47/RD4 "Gooney Bird" aircraft. During some flights, the M2-F1 included a small rocket motor.

M2-F1 test flights showed that the lifting-body concept had promise, so NASA funded a program of lifting body development and test flights at FRC. It lasted from 1966 into the 1970s.

The M2-F1 confirmed, however, what 1950s experiments had shown: that lifting bodies become increasingly unstable as their speed decreases. With this in mind, in January 1964, Clarence Cohen, Julius Schetzer, and John Sellars, engineers with the aerospace firm TRW, filed a patent application for a piloted lifting-body spacecraft design that could accomplish what they called a "staged reentry." The U.S. Patent Office granted their patent (No. 3,289,974) on 6 December 1966.

Explaining the need for their invention, the TRW trio noted that the Mercury capsule, flown for the last time in May 1963, had given its astronaut occupant essentially no ability to alter his spacecraft's course after he fired its solid-propellant deorbit rocket motors. The astronaut could control the timing of his deorbit burn; an early burn would cause his capsule to plunk into the ocean short of its planned splashdown area, while a delayed burn would cause it to overshoot its target.

The Mercury astronaut could not use the atmosphere to steer his capsule any great distance away from the ground track of its orbit. In aerospace terms, the Mercury capsule followed a ballistic trajectory from deorbit burn to splashdown and had very limited cross-range capability. The ballistic trajectory subjected the Mercury astronaut to a deceleration load equal to about eight times the pull of Earth's gravity.

The Gemini and Apollo reentry capsules, under development at the time Cohen, Schetzer, and Sellars filed their patent, would each feature an offset center of gravity about which they could roll while they moved at high speed through Earth's upper atmosphere. This would provide some lift and cross-range capability and help to limit deceleration loads. Both capsules would, however, become unsteerable and lose lift as they lost speed. Neither could be guided toward a specific touchdown point after their parachutes deployed. Steerable triangular parawings had been proposed for both, but such systems were judged to be too complex, heavy, costly to develop, and prone to failure.

The flat-bottomed DynaSoar - not a lifting body - had been designed for both steerable, low-deceleration Earth atmosphere reentry and stability and steerability at low speeds; however, the Department of Defense space plane's flat belly and narrow-edged wings and fins made it difficult to cover with heat shield materials. Protecting the triangular glider adequately from reentry heating threatened to boost its weight so much that its ability to maneuver in the lower atmosphere might be compromised.

Cohen, Schetzer, and Sellars' staged reentry spacecraft was really two vehicles: a fairly conventional (though quite compact) two-seater jet plane and a lifting-body "pod." The delta-winged jet would nest within the upper part of the pod with its bubble cockpit canopy protruding from the lifting body's flat top surface.

Partial cutaway drawing showing the small jet plane nested within the lifting-body "pod." One of the jet's pair of downturned vertical stabilizers is visible. Image credit: U.S. Patent Office/TRW
Standing atop an unspecified two-stage booster rocket on the launch pad before liftoff, the staged-reentry spacecraft would point its bulbous nose at the sky. The crew would enter through a hatch in the side of the streamlined fairing linking the lifting body to the booster, then would climb up through a drum-shaped airlock in the lifting body's flat aft bulkhead to reach acceleration couches arranged one behind the other (one above the other on the launch pad) in the lifting-body pod. The mission commander would take the front/top couch. Both couches would face control consoles.

The pod would include two abort rockets and one deorbit/abort rocket. In the event of booster malfunction during first-stage operation, the astronauts could ignite the three aft-facing rocket motors to blast their spacecraft free of the booster. The crew couches would automatically move up rails into the jet airplane cockpit and hatches would close in the plane's belly, sealing the crew inside. After the abort engines expended their propellants, the astronauts would separate from the pod in the jet and descend to a controlled landing at the launch site or at any airport within several hundred miles of the abort point.

Assuming, however, that an abort did not become necessary, the two abort rockets would eject out the back of the lifting body immediately after second-stage ignition. Cohen, Schetzer, and Sellars estimated that discarding the unused motors at that point in the flight would enable extra payload in Earth orbit equivalent to 90% of the motors' mass.

Riding the rails: TRW's method for moving astronauts between the lifting-body pod and the jet airplane cockpit is reminiscent of Gerry Anderson's Thunderbirds. Image credit: U.S. Patent Office/TRW
Once in orbit, the jet airplane canopy would provide the crew with views of the Earth and space. The crew could ride their couches up and down the rails to move between the pod and the jet airplane. In addition to living space, the pod volume would contain payload (for example, in-flight experiment gear), avionics, and life support equipment. The jet plane's belly, wing undersides, and single air intake cowl would form the "ceiling" of most of the pod living space.

The internal arrangement of the pod was, however, of little real concern to the TRW engineers; in fact, they argued that the lifting-body pod might serve merely as a "jettisonable heatshield" fitted with deorbit and abort rocket motors and avionics. In that case, the jet airplane cockpit would comprise the staged-reentry spacecraft's sole crew volume. 

TRW's staged reentry vehicle viewed from above and aft. A = jet airplane canopy; B = panel protecting jet airplane's nose; C = top surface of airplane fuselage and wings; D = lifting body top surface; E = jet airplane horizontal flap (1 of 2); F = lifting body underside; G = ejectable abort rocket motor (1 of 2); H = deorbit/abort rocket motor; I = parachute/landing aids compartment cover; J = movable control flap with actuator (1 of 4); K = flat aft bulkhead; L = airlock outer hatch. Image credit: U.S. Patent Office/TRW
Cohen, Schetzer, and Sellars envisioned that the crew would have at their disposal a display that would show landing areas on Earth as they passed within range of their orbiting spacecraft. When the desired target landing area came within range, the crew would command the computer that generated the display to orient the spacecraft using small thrusters so that its flat aft bulkhead pointed in its direction of motion. It would then ignite the deorbit rocket motor. As the spacecraft fell toward the atmosphere, the thrusters would automatically turn it so that its nose faced in its direction of motion. The crew, meanwhile, would ride their couches into the jet airplane cockpit.

As the spacecraft entered the atmosphere, four aft-mounted movable control flaps would adjust ("trim") the amount of lift the lifting-body shape would generate. At first, the spacecraft would descend at a shallow angle designed to limit the deceleration felt by the crew to less than twice the pull of Earth's gravity. The crew could, if required, take advantage of the lifting body's cross-range capability to steer toward landing sites far north or south of their orbit ground-track. 

The jet airplane detaches from the lifting-body pod. A = empty abort rocket compartment (1 of 2); B = experiment equipment and supplies; C = jet airplane separation rod with mounting pin (1 of 3); D = panel covering subsystems (for example, life support equipment); E = jet engine; F = vertical stabilizer (1 of 2); G = vertical control surface (1 of 2); H = rear landing skid (1 of 2). Image credit: U.S. Patent Office/TRW
Twelve minutes after the start of reentry, at an altitude of about 50,000 feet, the staged-reentry spacecraft would drop below supersonic speed, after which "staging" - separating the jet airplane bearing the crew from the plummeting lifting-body pod - could occur at any time. Separating the jet would open the pod crew volume to the outside environment. The pod would then deploy a parachute and other landing aids (for example, a flotation system) from an aft-mounted compartment and descend nose-down almost vertically to a splashdown or land landing. The problem of lifting-body instability at low speed would thus be eliminated.

In some ways, this approach resembled the Soviet Vostok land landing method. Vostok, the first piloted orbital spacecraft, was a modified spy satellite. Its spherical reentry capsule landed at too high a speed for the cosmonaut inside to escape injury, so he or she ejected low in the atmosphere, deployed a personal parachute, and descended separate from the capsule.

The TRW engineers expected that the astronauts could land safely in the lifting-body pod if they could not separate from it in the jet plane. Assuming, however, that they separated as planned, they would glide away from the pod in the jet. After they ignited the jet's engine, they would fly around the landed pod to locate it for recovery personnel, then land at a predesignated airport. The subsonic jet would carry enough fuel to permit the astronauts to reach backup airports if, for example, weather conditions became uninviting at the predesignated landing site.

By the time the U.S. Patent Office granted Cohen, Schetzer, and Sellars their patent in December 1966, NASA FRC had begun flights of the M2-F2, an all-metal lifting body built by the Northrop Corporation. It was the first of NASA's "heavyweight" lifting bodies. The research aircraft was designed to be borne aloft beneath the wing of a specially modified B-52 and released so that it could glide to a landing on a dry lake bed runway at Edwards AFB. After it proved itself in gliding flight, pilots would ignite the M2-F2's single four-chamber XLR-11 rocket engine for high-speed and high-altitude tests.

NASA's M2-F2 heavyweight lifting body (left) flies beside an F-104 chase plane, 16 November 1966. Image credit: NASA
Perhaps because lifting bodies had a reputation for being difficult to fly, engineers and test pilots were slow to acknowledge that the M2-F2 had significant, correctable control problems. Specifically, it was "soft" (slow) in responding to pilot control inputs, and prone to wild pilot-induced roll oscillations. On 10 May 1967, on its 16th flight, these problems caught up with the M2-F2. With Bruce Peterson at its controls, the M2-F2 crashed onto the Edwards AFB dry lake bed and flipped end over end six times. Miraculously, Petersen survived. Just as miraculously, so did NASA's lifting body research program.

Over the next three years, the M2-F2 was redesigned and rebuilt as the M2-F3, which included a third vertical stabilizer. The new centrally mounted fin markedly improved the aircraft's control characteristics.

The M2-F3 lifting body in 1970. Image credit: NASA
Between 2 June 1970 and 20 December 1972, the M2-F3 flew 27 times. After three unpowered gliding flights, William Dana lit up the M2-F3's XLR-11 rocket engine after release from the B-52 to accomplish its first powered flight (25 November 1970). During its 26th flight (13 December 1972), with Dana at the controls, the M2-F3 reached its fastest speed (Mach 1.6, or 1.6 times the speed of sound). On its final flight, John Manke took the aircraft to its highest altitude (71,500 feet). A year later, NASA transferred the M2-F3 to the collections of the Smithsonian Institution in Washington, DC, for display.

Sources

Patent No. 3,289,974, "Manned Spacecraft With Staged Re-Entry," C. Cohen, J. Schetzer, and J. Sellars, TRW, 6 December 1966

Apollo Final Report: Configuration, ER 12004, The Martin Company, June 1961

Wingless Flight: The Lifting Body Story, R. Dale Reed with Darlene Lister, NASA SP-4220, The NASA History Series, 1997

International Rescue Thunderbirds Agents' Technical Manual, Sam Dunham with Graham Bleathman, Haynes Publishing, 2012

08 February 2017

NASA Johnson Space Center's Shuttle II (1988)

Image credit: NASA
Although the fact is mostly forgotten today, NASA launched plans to augment or replace the Space Shuttle even before the first Shuttle reached orbit on 12 April 1981. Much - though by no means all - of this planning occurred as part of joint Department of Energy/NASA Solar Power Satellite studies.

In 1985, U.S. President Ronald Reagan signed a directive ordering the U.S. civilian space agency to develop a Space Shuttle successor. Notably, this occurred before the 28 January 1986 Challenger accident laid bare the Shuttle system's many frailties.

One proposed Shuttle successor was called Shuttle II. Most Shuttle II design work took place at NASA's Langley Research Center (LaRC) in Hampton, Virginia. Shuttle II first achieved prominence in 1986 in the high-level National Commission On Space report Pioneering the Space Frontier.

LaRC's Shuttle II design evolved - for a time it was to have been a single-stage-to-orbit vehicle. The favored design included a winged manned Orbiter and a winged unmanned Booster, both of which would take off vertically and land horizontally on runways. Both the Booster and the Orbiter would be entirely reusable. LaRC's Shuttle II Orbiter fuselage was meant to be crammed full of propellant tanks, so would tote cargo in a sizable hump on its back.

NASA Langley Research Center's dumpy Shuttle II, 1987. Image credit: NASA
Shuttle II was intended mainly as a crew transport complementing a "mixed fleet" of launchers that would have included unmanned heavy-lift rockets capable of placing from 50 to 100 tons into space. LaRC envisioned that its Shuttle II would transport a small amount of cargo - perhaps 10 tons - and up to 25 astronauts, of whom only three would be considered Shuttle II crew members. The remainder would be passengers bound for a large advanced Space Station or a Transportation Node station where they would board spacecraft bound for the moon or Mars.

Although a good case can be made for calling LaRC's Shuttle II the Shuttle II, it was in fact not the only proposed Shuttle II design. The Advanced Programs Office at NASA Johnson Space Center (JSC) in Houston, Texas, put forward the sleek Shuttle II design depicted in the last seven images of this post. They portray JSC's Shuttle II as it would appear over the course of a typical mission.

The LaRC design was favored by NASA Headquarters and is relatively well documented. Neither can be said for JSC's design.

In flight: the Evolved Shuttle climbs toward space, probably sometime in the 1990s. Image credit: Eagle Engineering/NASA
Model of proposed Evolved Shuttle showing major components. Image credit: NASA
Engineers in Houston envisioned that their Shuttle II might develop from an Evolved Space Shuttle. In the Evolved Shuttle, Liquid Replacement Boosters stood in for the Shuttle's twin Solid Rocket Boosters. The Evolved Shuttle would retain the Shuttle's expendable External Tank and, with minor modifications, the reusable Orbiter's Space Shuttle Main Engines (SSMEs). Like the Space Shuttle, the Evolved Shuttle stack would ride to its Launch Complex 39 pad atop a creeping crawler-transporter with its nose aimed at the sky.

Winglets on the tips of the Evolved Shuttle's modified delta wings would replace the Shuttle's single vertical tail fin. Redesigned Orbital Maneuvering System (OMS) engines based on the venerable RL-10 engine would draw liquid hydrogen/liquid oxygen propellants from insulated tanks built into the Evolved Shuttle Orbiter's wings.

The most dramatic changes were, however, reserved for the Evolved Shuttle's crew compartment. JSC engineers designed it so that it could separate from the Evolved Shuttle in the event of catastrophic failure and operate as an independent spacecraft. Canard winglets meant to improve the Evolved Shuttle's aerodynamic characteristics would separate with the crew compartment and become its wings.

JSC gave no timeline for the evolution of Shuttle to Evolved Shuttle. If, however, JSC's Shuttle II was to become operational in the same timeframe as LaRC's Shuttle II (the early 21st century), then one may assume that the Evolved Shuttle would have made its debut in the 1990s.

Shuttle II ready for a tow to its launch pad. A round panel covering an extendable docking adapter is visible just above the American flag on the fuselage. Image credit: NASA
JSC's Shuttle II was meant to be towed horizontally on its tricycle landing gear from a hangar to its launch pad just four hours before planned launch. Unlike the Space Shuttle and Evolved Shuttle, JSC's Shuttle II would have no need of Kennedy Space Center's Vehicle Assembly Building, the massive cuboid structure built in the 1960s for the assembly of Apollo Saturn V heavy-lift rockets.

Nor would it use the twin Launch Complex 39 pads, which were built in the 1960s to launch Saturn V rockets and rebuilt in the 1970s to launch the Space Shuttle. Shuttle II would instead lift off from a new-design pad, and Complex 39 would be given over once again to heavy-lift rocket launches. In fact, JSC's Shuttle II would make a complete break from the massive-scale Apollo-era infrastructure upon which the Space Shuttle relied.

JSC's Shuttle II in launch configuration. The round panel covering the extendible docking adapter is again visible; it leads to a crew access tunnel that runs the length of the spacecraft. Image credit: NASA
At the launch pad, crew and passengers would board JSC's Shuttle II, then it would be tipped up to point its dome-shaped nose at the sky. Its landing gear doors would be closed, then its ground crew - small compared with the army of personnel that serviced the Space Shuttle - would load it with three kinds of propellants: liquid hydrogen fuel, liquid hydrocarbon (kerosene or propane) fuel, and liquid oxygen oxidizer.

For safety, most of the volatile fuels would be pumped into Shuttle II's four expendable over-wing tanks, while an integral, reusable tank within the spacecraft would carry most of the dense liquid oxygen. Fully loaded with propellants and payload, Shuttle II would weigh about 550 tons, or a little more than a quarter of the Shuttle's weight at SSME ignition.

JSC designers hoped to minimize Shuttle II's weight in part by building it from advanced materials. The Space Shuttle Orbiter, with an empty mass of about 85 tons, had a more-or-less conventional load-bearing aluminum-titanium airframe clad in lightweight thermal-protection materials. These included thousands of uniquely shaped ceramic tiles and Reinforced Carbon-Carbon (RCC) wing leading edges. Shuttle II, with an empty mass of 50 to 75 tons, would also rely on RCC, "but in larger, load-bearing, monolithic panels." The over-wing tanks would be made from lightweight welded aluminum-lithium alloy.

At launch, Shuttle II's single Space Transportation Main Engine (STME) and twin Space Transportation Boost Engines (STBEs) would ignite simultaneously. The former, designed to burn liquid hydrogen and liquid oxygen, was envisioned as a second-generation SSME. The latter would burn hydrocarbon fuel and liquid oxygen and employ liquid hydrogen as engine coolant. The STME and STBEs would together generate about 30% more thrust than the Space Shuttle's three SSMEs - between 1.3 and 1.6 million pounds.

Climb to orbit: JSC's Shuttle II following detachment of its outboard tanks and its STBEs. Image credit: NASA
When it reached a velocity of between two and three kilometers per second, JSC's Shuttle II would shed its depleted outboard over-wing tanks and the STBEs. Dropping the STBEs would improve Shuttle II's flight performance by shifting its center of gravity forward. The tanks would break up and fall into the sea, but NASA would recover the twin engines for reuse. JSC engineers envisioned that they would descend in reentry shells, deploy maneuvering parachutes, and land in arresting nets aboard recovery ships.

The STME, meanwhile, would extend its telescoping exhaust nozzle to its full length and diameter to improve its performance in vacuum. Following separation of the outboard tanks and STBEs, the spacecraft would burn only liquid hydrogen/liquid oxygen propellants.

Immediately following STME cutoff, the engine's nozzle would retract and the inboard over-wing tanks would be cast off. Upon reaching apogee (the highest point in its orbit about the Earth), Shuttle II's twin OMS engines would ignite to raise its perigee (the lowest point in its orbit) out of the atmosphere. This would place it into a circular "Space Station rendezvous orbit" 485 kilometers high inclined 28.5° relative to Earth's equator. The inboard tanks, meanwhile, would intersect Earth's atmosphere as they reached perigee and be destroyed.

The Shuttle II OMS would comprise a pair of new-design Advanced Space Engines or RL-10-derived engines. RL-10 had the advantage of a long flight history; derivatives of that engine have propelled upper stages and spacecraft since the 1960s. Liquid hydrogen and liquid oxygen for both Shuttle II's OMS and the Reaction Control System (RCS) thrusters would be stored in double-walled, heavily insulated tanks in Shuttle II's tail section. Some propellants from the tail section would be combined in next-generation fuel cells to generate electricity and water for the spacecraft.

A crew access tunnel would run aft from the forward crew compartment for most of the length of the fuselage. Midway along the tunnel, on its left side, Shuttle II's docking adapter for linking up with the Space Station would be stowed behind a streamlined panel. The round panel is visible near the American flag in images that display the Shuttle II model's left side. Prior to rendezvous with the Space Station, the panel would hinge out of the way, then the crew would extend the cylindrical docking adapter.

The image above shows Shuttle II in its orbital configuration with inboard tanks in place; this is apparently a photographer's error, since image captions make plain that the inboard tanks would separate immediately after STME cutoff, before the crew opened the payload bay. Image credit: NASA
JSC engineers chose a novel method for exposing Shuttle II payloads to space: the crew would disable the OMS engines, vent and disconnect hoses that had linked the over-wing tanks to the STME, disengage locks, and hinge the tail section downward using electric motors. RCS thrusters in the tail would continue to operate; to minimize flexible wiring links between the main fuselage and the tail section, engineers proposed that the astronauts control the RCS thrusters via a short-range radio link.

Hinging the tail section down would expose a large round window and the open aft end of the 15-foot-wide-by-30-foot-long cylindrical payload bay. Astronauts at an aft work station would look out through the window as they extended the cradle bearing their mission's payload. The photo captions do not name specific Shuttle II payloads, but it is logical to assume that these would include experiment packages for mounting on the Space Station and reusable Station logistics modules packed full of supplies and equipment. The payload bay would contain an airlock for spacewalks and a pair of robot arms.

Unlike the Space Shuttle and Evolved Shuttle payload bays, the Shuttle II bay would normally not include radiators for dissipating heat generated by onboard equipment and astronaut exertions. Instead, Shuttle II's radiators would be built into the top surface of its wings. Supplemental radiators would be mounted on the payload cradle only "for special purpose, high heat load conditions."

Before return to Earth, the astronauts would retract the payload cradle, then hinge shut the tail section. Shuttle II would include triple-redundant electric motors and a mechanical backup system for closing the payload bay "to assure that the vehicle configuration for entry [would] not have paths for hot plasma to enter the vehicle interior." During the first few Shuttle II flights, an astronaut would exit through the docking adapter and clamber over the fuselage to inspect the hinge area and seam between the tail section and the rest of the spacecraft. He or she might carry a repair kit "to fill any voids."

Reentry would occur as in the Space Shuttle Program; that is, Shuttle II would turn so that its aft end pointed in its direction of flight, then its OMS engines would ignite to reduce its orbital velocity. The spacecraft would then flip to point its nose forward as it fell toward the atmosphere. Following reentry, Shuttle II would glide to a runway landing.

JSC's Shuttle II in landing configuration. Image credit: NASA
Unlike the Space Shuttle, which even after the Challenger accident included few realistic options for crew escape in the event of catastrophic failure, Shuttle II could in theory protect its crew through all phases of its mission. Like the Evolved Shuttle, Shuttle II would include a separable crew compartment; after separation, Shuttle II's canard fins - proportionately larger than those of the Evolved Shuttle - would become the crew compartment's wings.

The crew compartment aft end would include launch escape/deorbit rocket rocket engines, a crew hatch, and a deployable aerodynamic flap. Following separation in orbit, the crew compartment could support 11 astronauts for up to 24 hours. This endurance was meant to ensure that Earth's rotation could bring into range a suitable landing site on U.S. soil. The crew compartment would touch down and slide to a halt on extendable skids.

Crew cabin separation on the launch pad or during ascent. Image credit: NASA
Crew cabin separation in orbit or during reentry. Image credit: NASA
JSC engineers acknowledged that wind-tunnel testing might show that the Shuttle II crew compartment shape was not flight-worthy in all abort situations. They proposed that inflatable or extendable structures "be employed to obtain an acceptable configuration for hypersonic, supersonic, and subsonic controlled flight."

They also proposed that the Shuttle II crew compartment become the Space Station's Crew Emergency Rescue Vehicle (CERV). The CERV was conceived as a "lifeboat" for use if the Space Station had to be evacuated rapidly, if a crew member became seriously ill or injured and needed hospital treatment on Earth, or if Shuttle II became grounded due to malfunction or accident and could not retrieve a Space Station crew.

The JSC engineers noted that the Shuttle II crew compartment/CERV, like Shuttle II itself, would subject its occupants to no more than three gravities of acceleration or deceleration. This would help to ensure that, during return to Earth, it would not inflict additional harm on a sick or injured Space Station crewmember.

NASA continued to attempt to develop a Shuttle successor - a winged spacecraft that would enable it to apply the lessons learned from the Shuttle Program. Some proposed complex new vehicles employing scramjets; others, vehicles smaller and less capable than the Shuttle tailored mainly for Space Station crew rotation and crew escape. Unfortunately, The space agency's budget was not expanded to permit simultaneous ongoing Shuttle operations, Space Station development and assembly, and development of a Shuttle successor.

By the mid-1990s, many in the Shuttle Program had changed their tactics; they declared that the Shuttle should continue to fly at least until 2010. In 2001, Boeing proposed that the Shuttle should fly until 2030.

The 2003 Columbia accident ended such plans. When the Shuttle was retired in 2011, a new NASA Shuttle design was as far away as it had been during Shuttle II planning in the late 1980s.

Sources

Caption Sheet, NASA Photo S88 29029, Shuttle II Candidate Configuration, 1988

Caption Sheet, NASA Photo S88 29035, Shuttle II Launch Configuration, 1988

Caption Sheet, NASA Photo S88 29032, Shuttle II Post-Boost Flight Configuration, 1988

Caption Sheet, NASA Photo S88 29028, Shuttle II Orbital Flight Configuration, 1988

Caption Sheet, NASA Photo S88 29026, Shuttle II Entry and Landing Configuration, 1988

Caption Sheet, NASA Photo S88 29024, Shuttle II Pad Abort Crew Escape, 1988

Caption Sheet, NASA Photo S88 29030, Shuttle II Crew Escape System, 1988

Caption Sheet, NASA Photo S89 34837, Evolved Shuttle, 1989

"Shuttle II Progress Report," T. Talay, NASA Langley Research Center; paper presented at the 24th Space Congress, 21-24 April 1987, Cocoa Beach, Florida

Pioneering the Space Frontier: the Report of the National Commission on Space, Bantam Books, 1986

"At 15, A Safer, Cheaper Shuttle," J. Asker, Aviation Week & Space Technology, 8 April 1996, pp. 48-51

"Boeing upgrade would keep Space Shuttle flying to 2030," G. Warwick, Flight International, 8-14 May 2001, p. 37

More Information

Electricity from Space: The 1970s DOE/NASA Solar Power Satellite Studies

What If a Space Shuttle Orbiter Had to Ditch? (1975)

What Shuttle Should Have Been: NASA's October 1977 Space Shuttle Flight Manifest

One Space Shuttle, Two Cargo Volumes: Martin Marietta's Aft Cargo Carrier (1982)