23 March 2017
I've been engaged in the blogging equivalent of spring cleaning since Monday. I hadn't planned on doing this. Over the weekend, however, I discovered I'd made an error in interpretation that spread across several posts. Basically, I had come to believe that the Phase B Extension Space Station studies McDonnell and North American Rockwell performed in 1971-1972 had begun in June 1970. Phase B studies were indeed extended at that time; however, the Phase B Extension studies were something different. They started officially on 1 February 1971 and continued into late 1972.
The Phase B studies looked at single-launch core Station designs and then shifted to include Shuttle-launched modular designs; the Phase B Extension studies studied Shuttle-launched modular designs and shifted to include the "sortie lab" concept, which led to the European-built module we called Spacelab. The transition from one proposed Station concept to the next was not, however, tidy: as John Logsdon notes in his report Space Stations: A Policy History, written for NASA Johnson Space Center, NASA was in September 1970 holding workshops to educate potential users about the potential of the 33-foot-diameter Saturn V-launched core station; preparing a Statement of Work and performing in-house studies in support of the Shuttle-launched modular Station study; and preparing budget recommendations that turned the Space Station Program into a mere advanced program study for the foreseeable future.
I have repaired the damage. Along the way I discovered some other errors. Most were mere typos, but one was a howler. Did I really type that? I think my brain must have wandered off while my fingers performed a modern interpretive dance on my keyboard.
I read through all 104 posts on this blog and made corrections when I found errors. I think my spring cleaning is done now. If, however, any of you notice anything that you suspect is an error, please let me know.
Space Stations: A Policy History, John M. Logsdon, Graduate Program in Science, Technology, and Public Policy, NASA Johnson Space Center, no date (1980), p. II-32
18 March 2017
|During the STS-91 (2-12 June 1998) mission to the Russian Mir space station, the Space Shuttle Orbiter Discovery carried four pairs of GAS canisters along its Payload Bay walls. The red arrow points to one pair. Image credit: NASA|
If four engineers at the Jet Propulsion Laboratory (JPL) in Pasadena, California, had had their way, a GAS payload might have traveled far beyond LEO. In May 1987, the team proposed that an advanced-design small spacecraft be launched on board a Space Shuttle inside an Extended GAS canister and ejected into Earth orbit. The spacecraft, called Lunar GAS (LGAS), would then use electric-propulsion thrusters to spiral outward to the moon.
|Close-up of two of the STS-91 GAS canisters in Discovery's Payload Bay. Image credit: NASA|
The LGAS mission would begin up to three months before planned Space Shuttle launch with the insertion of the 149-kilogram spacecraft into its Extended GAS canister. The spacecraft would at that point enter the routine GAS payload processing flow and no one would see it again until it left its canister in LEO.
The Shuttle Orbiter bearing the LGAS spacecraft would lift off from Kennedy Space Center in Florida and enter an orbit inclined 28.5° relative to Earth's equator. The astronauts would then open its payload bay doors, exposing the closed Extended GAS canister bearing LGAS to space.
NASA required that GAS experiments place minimal demands on Shuttle expendables and astronaut time. The JPL team insisted that, despite its complexity, the LGAS mission could meet this requirement. A few hours after launch, one astronaut would flip a single switch on the Shuttle flight deck to open the motorized Extended GAS canister lid, then would flip two more to release a latch and activate a spring ejection mechanism.
|Simplified schematic of the LGAS spacecraft following deployment from its GAS canister. Image credit: JPL/NASA|
Two small chemical-propellant thrusters would turn the spacecraft to point its solar arrays and spin axis toward the Sun, then would spin its barrel-shaped body end over end at up to five revolutions per minute to create gyroscopic stability. After it had moved a safe distance away from the Shuttle, the LGAS spacecraft would switch on one of its twin electric thrusters. Mounted on opposite sides of the spacecraft body, these would take turns thrusting parallel to its spin axis. Fueled from a round tank containing 36 kilograms of compressed xenon gas, the thrusters would each be designed to withstand 3500 start/stop cycles and to operate for a total of 4500 hours (187.5 days).
|LGAS spacecraft electric-propulsion thrust and coast arcs during escape from Earth orbit. Image: JPL/NASA|
In the third arc, the second thruster would point opposite the LGAS spacecraft's direction of motion, so it would switch on to take its turn accelerating the spacecraft. In the fourth arc, which would see the spacecraft pass between the Earth and the Sun, the thrusters would again point perpendicular to its direction of motion, so would not operate.
Overcoming drag from Earth's atmosphere would require about one-third of the LGAS spacecraft's thrust early in the departure spiral, the team calculated, but drag would taper off quickly as the spacecraft raised its orbital altitude by up to 20 kilometers per day. Starting about three months after launch from the Shuttle, the LGAS spacecraft would spend between 100 and 150 days inside the Earth-girdling Van Allen Belts. High-energy particles in the Belts would gradually degrade the twin wing arrays, reducing their electricity output.
|Image credit: JPL/NASA|
The xenon-fueled thrusters would then resume alternating operation with their 90° thrust arcs centered over the moon's polar regions; this time, however, the thrusters would point in the spacecraft’s direction of motion when they operated, gradually slowing the LGAS spacecraft so that it would spiral in toward the moon.
The spacecraft would achieve a 100-kilometer-high, two-hour lunar polar orbit about two years after it departed its Extended GAS canister. In its orbit over the moon's poles, the moon would rotate beneath it about once per month, enabling it to eventually overfly the entire lunar surface. Irregularities in the moon's gravity field would mean that the electric thrusters would need to adjust the spacecraft's orbit about every 60 days.
The LGAS spacecraft would have room for only one science instrument: a 15-kilogram gamma-ray spectrometer (GRS) for charting the composition of the moon's crust. The JPL engineers proposed that the unflown Apollo 18 GRS be mounted on the LGAS science boom. Lunar-orbital science operations would continue for about one year.
"Lunar Get Away Special (GAS) Spacecraft," AIAA-87-1051, K. T. Nock, G. Aston, R. P. Salazar, and P. M. Stella; paper presented at the 19th AIAA/DGLR/JSASS International Electric Propulsion Conference in Colorado Springs, Colorado, 11-13 May 1987
"Getaway Special," Wikipedia,
https://en.wikipedia.org/wiki/Getaway_Special (accessed 18 March 2017)
The Eighth Continent
On the Moons of Mighty Jupiter (1970)
Cometary Explorer (1973)
Catching Some Comet Dust: Giotto II (1985)
06 March 2017
One-Man Space Station (August 1960)
Space Station Gemini (December 1962)
Space Station Resupply: The 1963 Plan to Turn the Apollo Spacecraft Into a Space Freighter (November 1963)
"Assuming That Everything Goes Perfectly Well in the Apollo Program. . ." (January 1967)
"A True Gateway": Robert Gilruth's June 1968 Space Station Presentation
McDonnell Douglas Phase B Space Station (June 1970)
From Monolithic to Modular: NASA Establishes a Baseline Configuration for a Shuttle-Launched Space Station (July 1970)
An Alternate Station/Shuttle Evolution: Spirit of '76 (August 1970?)
A Bridge from Skylab to Station/Shuttle: Interim Space Station Program (April 1971)
Skylab-Salyut Space Laboratory (June 1972)
What If a Crew Became Stranded On Board the Skylab Space Station? (October 1972)
Reviving and Reusing Skylab in the Space Shuttle Era: NASA Marshall's November 1977 Pitch to NASA Headquarters
Evolution vs. Revolution: The 1970s Struggle for NASA's Future (1978)
Bridging the Gap Between Space Station and Mars: The IMUSE Strategy (July 1985)
Naming the Space Station (1988)
The 1991 Plan to Turn Space Shuttle Columbia Into a Low-Cost Space Station (July-September 1991)
NASA's 1992 Plan to Land Soyuz Lifeboats in Australia (November 1992)
A Chronological Presentation: The Apollo-to-Shuttle Transition 1.0
27 February 2017
|Image credit: NASA|
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.
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|
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|
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.
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.
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|
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|
Patent No. 3,289,974, "Manned Spacecraft With Staged Re-Entry," C. Cohen, J. Schetzer, and J. Sellars, TRW, 6 December 1966
Wingless Flight: The Lifting Body Story, R. Dale Reed with Darlene Lister, NASA SP-4220, The NASA History Series, 1997
08 February 2017
|Image credit: NASA|
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|
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|
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|
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|
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|
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.
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|
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|
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.
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
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)
31 January 2017
As Gemini Was to an Apollo Lunar Landing by 1970, So Apollo Would Be to a Permanent Lunar Base in 1980 (1968)
|Cutaway of the Apollo Lunar Module (LM) showing its ascent stage (top) and descent stage (bottom). A total of six descent stages were left on the lunar surface at six separate sites between July 1969 and December 1972. Image credit: NASA|
NASA then ramped up Apollo exploration by stretching lunar surface stay time to three days, upgrading the Apollo lunar suits to permit moonwalks of about seven hours, and providing the astronauts with a Boeing-built lunar "jeep" - the Lunar Roving Vehicle (LRV) - to extend their exploration range. Apollo 15 (26 July-7 August 1971) exploited these new capabilities to survey Hadley-Apennine, a complex site between mountains and a winding rille (canyon). Apollo 16 (16-27 April 1972) was the only mission to land in the heavily-cratered lunar highlands. Apollo 17 (7-19 December 1972) concluded the Apollo Program with a visit to Taurus-Littrow, where Harrison Schmitt, the only professional geologist to explore the moon, found tiny orange glass beads - remnants of ancient volcanic fire fountains - with his feet.
In addition to intensively exploring the selected site, the astronauts would have performed engineering and life sciences experiments, assessed the lunar environment for radio and optical astronomy, and experimented with resource exploitation. The single site revisit missions would have played the role for a permanent lunar base that Project Gemini played for Apollo; that is, it would have enabled NASA to acquire operational skills needed for its next step forward in space.
The Sub-Group's report began by declaring that a 12-man "International Lunar Scientific Observatory" in 1980 could become a new "Major Agency Goal" for NASA following Apollo. The single site revisit missions, it continued, would pave the way to the new lunar goal by demonstrating the value of a permanent base on the moon. The Sub-Group then examined four options for carrying out its single site revisit program, which it labeled 0, A, B, and C. All would employ spacecraft and standard Saturn V launch vehicles the space agency had already ordered for Apollo.
The first of the four options, Option 0, would employ the basic Apollo Lunar Module (LM), which could support two men on the moon for 24 hours and deliver 300 pounds of cargo to the lunar surface. Three Option 0 missions would visit the single site, where their crews would perform a total of six moonwalks on foot and minimal exploration and technology experimentation. The Sub-Group rejected this option out of hand because it would provide NASA with insufficient experience ahead of the 1980 lunar base.
The first Option A mission, scheduled for the fourth quarter of 1971, would see two astronauts conduct from four to six moonwalks and up to four traverses using a rocket-propelled Lunar Flying Unit (LFU) fueled using residual propellants in the ELM-A descent stage. In addition to exploring the single site's geology, the astronauts would set up a "technology package" to assess the moon's "optical environment" for astronomy. They would also deploy exposure samples to test the effects of the lunar environment on materials and coatings that might be used to build the 1980 moon base. When they left the single site in the ELM-A ascent stage to rejoin their lone comrade on board the orbiting Apollo Command and Service Module (CSM), they would leave behind for the next crew tools, the LFU, the exposure samples, and the optical environment package.
The second Option A mission would take place in the second quarter of 1972. The astronauts would carry out six moonwalks and, after servicing the LFU, up to four flying traverses. The LFU would amount to a exposure experiment; it would need to work reliably after being parked at the single site for six months (that is, through six lunar day-night cycles). The astronauts would also set up an "advanced" Apollo Lunar Scientific Experiment Package (ALSEP) and a technology package to assess the lunar environment's suitability for radio astronomy. Between moonwalks, they would perform unspecified biology experiments in the ELM-A cabin. Finally, they would retrieve for return to Earth some of the exposure samples left behind by the first Option A crew.
The third and final Option A mission would reach the single site in the fourth quarter of 1972, six months after the second. Its crew would perform six moonwalks, fly the LFU three or four times on geologic traverses, and observe the Sun using a small telescope they would bring with them to the site. They would also retrieve for return to Earth the remaining exposure samples left behind by the first Option A crew. If necessary, they would service the advanced ALSEP instruments deployed by the second Option A crew.
Option B mission 1 would last six days, during which time its crew would carry out from six to 10 moonwalks and up to four LFU geologic traverses. In addition to twin LFUs, the ELM-B would deliver an advanced ALSEP, geology tools, unspecified "biological colonies," and environment and technology exposure samples. As with the Option A missions, lunar environment experiments would focus on optics and radio.
Option B mission 2 would land in the fourth quarter of 1972 for a three-day stay. Its crew would perform six moonwalks and up to four LFU traverses. The three-day stay time would mean that the ELM-B could carry 750 pounds of cargo; this would include a solar telescope, plant and animal packages, and bioscience supplies. The crew would also examine the exposure samples left by the first Option B crew and service any equipment at the site that needed it.
The third Option B mission would land in the second quarter of 1973 and last for either three or six days depending on the results obtained during missions 1 and 2. Its crew would perform from six to 10 moonwalks and three or four LFU traverses. In addition to technology and astronomy experiments, the astronauts would retrieve and prepare technology and biology packages and exposure samples for return to Earth.
A 2000-pound cylindrical shelter capable of supporting two men on the lunar surface for from 12 to 14 days would constitute the heaviest LPM cargo item. In addition, the LPM would carry a pair of LFUs, tanks of LFU propellants, a "dual-mode" Lunar Roving Vehicle (LRV) capable of being driven by either astronauts on the moon or flight controllers on Earth, a solar furnace for technology and lunar resource exploitation experiments, a 12-inch reflecting telescope, laboratory equipment, bioscience packages, lunar environment exposure sample packages, and an advanced ALSEP.
While the Single Site Working Sub-Group called their unmanned LM an LPM, in fact it more closely resembled an LM derivative Grumman, the LM prime contractor, called an LM Truck. Grumman proposed two LM Truck types - one would carry only cargo atop a descent stage, while the other would carry cargo and a cylindrical shelter. Grumman's LPM would include an LM ascent stage to house the astronauts on the lunar surface, not a cylindrical shelter. Despite this, I will in this post continue to refer to the Sub-Group's unmanned LM derivative for Option C as an LPM.
The first of four Option C missions would see a piloted CSM deliver the LPM to lunar orbit at the beginning of 1973. The Single Site Working Sub-Group wrote that, in general, little CSM orbital science would occur in the single site revisit program. This was because much CSM orbital science was meant to support selection of multiple Apollo landing sites, which the single site revisit missions would make unnecessary. The LPM-delivery CSM would, however, remain in lunar orbit for some unspecified period after the LPM undocked. During that time, its crew would turn a suite of remote sensors toward the moon's surface and deploy a science subsatellite.
Option C mission 2, launched just one month after the LPM delivery mission, would employ a modified ELM designed to remain "quiescent" on the lunar surface while its crew lived in the LPM shelter. Grumman called the quiescent ELM the LM Taxi. Because most of its systems would be made dormant after landing, it would need fewer expendables than an ELM-B, permitting it to carry up to 750 pounds of cargo despite its 12-to-14-day lunar surface stay time. Cargo would include an LFU for transporting the two-man crew to and from the LPM in the event that navigational error caused them to land beyond walking distance.
The Option C mission 2 crew would perform many tests and experiments over the course of from 12 to 20 moonwalks, up to 14 LFU flights, and up to eight LRV traverses during their 12 to 14 days on the moon. Basically, they would accomplish all of the tasks planned for the three Option B missions and more; they would, for example, not only collect rock samples for return to Earth, they would also analyze them in the manner astronauts would at the 1980 moon base. Before returning to the quiescent ELM and blasting off to rejoin the CSM Pilot in lunar orbit, they would reconfigure the LRV for remote-controlled operation and turn it loose under guidance from controllers on Earth to travel tens or hundreds of miles across the lunar surface in a loop that would end back at the single site.
Option C mission 3, in the third quarter of 1973, would see an ELM-B land near the LPM with 750 pounds of cargo. The astronauts, who would live in the ELM-B would conduct from six to 10 moonwalks, four LFU flights, and up to four LRV traverses. In their most notable experiment, they would attempt to extract water from lunar dust and rocks using the solar furnace; if successful, this could lead to production of life support consumables and rocket propellants on the moon, slashing the cost of lunar base resupply. Before they left the moon, they would reconfigure the dual-mode LRV for remote-control operation.
Option C mission 4, a near-carbon copy of mission 3, would land in the first quarter of 1974. The crew would complete any on-going experiments at the LPM, observe the Sun, and retrieve biological colonies and exposure samples. They would also dispatch the dual-mode LRV on its longest remote-controlled traverse yet; because it would not again be driven by astronauts, it would not need to return to the LPM site and thus might wander for hundreds of miles across the lunar surface under the direction of controllers on Earth.
The Sub-Group then summed up "Major Conclusions" of its brief study. Only a few are noted here. The Sub-Group confided that the single site revisit missions could be portrayed as a part of the Apollo Program, not as a costly new program, thus avoiding possible political roadblocks. It also claimed that the single site revisit program would be "strongly identifiable with the public interest," though it did not specify how. Finally, the Sub-Group explained that the program would meaningfully exploit uniquely human capabilities: these included on-the-spot judgement; skilled observation (for example, rapid recognition of significant geological relations); and complex tool-using skills.
|Shortly after liftoff: the descent stage of the Apollo 17 LM Challenger abandoned in the Taurus-Littrow valley. Image credit: NASA|
They also contemplated where NASA might establish its 1980 moon base; the only specific sites they mentioned, however, were the two lunar poles. This was in keeping with the main body of their report, which provided no candidate sites for the single site revisit program. Finally, they sought guidance as to how they should proceed if the single site revisit option received no funding in NASA's Fiscal Year 1970 budget.
Some small movement toward including the single site revisit concept in NASA's Fiscal Year 1970 budget took place; however, most work on the concept ended with the Sub-Group's 4 June 1968 revised report to the LEWG. In retrospect, it seems likely that the concept would have split the lunar science community between those eager for data from as many landing sites as possible as soon as possible and those prepared to wait (perhaps in vain) for the enhanced exploration capabilities that would become available after the 1980 lunar base was established. In any case, it appears unlikely that an Apollo planning option that laid the groundwork for a costly long-term lunar presence could have gained much traction in Washington in 1968; by the time the Single Site Working Sub-Group began its deliberations, the Congress had already displayed a marked lack of enthusiasm for expansive post-Apollo space goals.
Report of the Lunar Exploration Working Group to the Planning Steering Group, revised 30 April 1968
Report of the Single Site Working Sub-Group to the Lunar Exploration Working Group, 22 May 1968 (revised 4 June 1968)
Memorandum with attachment, MTX/Chairman, Lunar Station Subgroup, to Distribution, "Meeting of the Lunar Station Subgroup," 7 May 1968
Memorandum with attachment, MAL/Director, Apollo Lunar Exploration Office to MTX/Rodney W. Johnson, "Lunar Single Site Working Subgroup," 7 May 1968
Apollo News Reference, Public Affairs Office, Grumman, 1969, pp. LMD-4, LMD-6-8
Conversations with Paul D. Lowman, NASA geophysicist and participant in the Single Site Working Sub-Group, at and around NASA Goddard Space Flight Center, Greenbelt, Maryland, Summer 2000
Early Apollo Mission to a Lunar Wrinkle Ridge (1968)
Robotic Rendezvous At Hadley Rille (1968)
"A Continuing Aspect of Human Endeavor": Bellcomm's January 1968 Lunar Exploration Program
Rocket Belts and Rocket Chairs: Lunar Flying Units
An Apollo Landing Near the Great Ray Crater Tycho (1969)
29 January 2017
Apollo fulfilled a perceived national need: specifically, to assert U.S. technological primacy in the Cold War with the Soviet Union. SEI, by contrast, seemed to fulfill no purpose commensurate with its projected cost. President John F. Kennedy called for Apollo at the Cold War's height; Bush proposed SEI as the Eastern Bloc disintegrated. Though Bush, a Republican, apparently felt genuine enthusiasm for space exploration, he distanced himself from SEI by the beginning of 1991, when it had become an obvious political liability.
The initiative continued with minimal funding until Democratic President William Jefferson Clinton took office in January 1993. By May of that year, when the Case for Mars V conference convened in Boulder, Colorado, NASA's moon and Mars exploration planning apparatus was in the process of being dismantled. The Case for Mars V became SEI's wake.
Geoffrey Landis, a NASA Lewis Research Center (now NASA Glenn Research Center) engineer and award-winning science-fiction author, presented a plan for recovery from SEI at The Case for Mars V. He subsequently published it in The Journal of the British Interplanetary Society. He began his paper by declaring that SEI was "politically dead" - it had, he wrote, come to be "viewed as an expensive Republican program with no place in the current era of deficit reduction." Landis then asked, "how can we advocate Mars exploration without appearing to be attempting to revive SEI?"
Landis's solution was a new piloted Mars program that would take into account lessons taught by Apollo ("If you accomplish your goal, your budget will be cut") and the Space Shuttle ("if you do the same thing over and over, the public will focus on your failures and forget your successes"). Landis's program was a 14-year series of incremental "footsteps" which, he said, would be in keeping with NASA Administrator Dan Goldin's "faster, better, cheaper" philosophy of spaceflight (at the time of The Case for Mars V, this philosophy was still in its infancy). The footsteps would, he argued, provide a series of interesting milestones that would maintain public enthusiasm for the program at least until a piloted Mars landing took place.
Landis's first footstep, which he optimistically asserted could occur "immediately," was a piloted Mars flyby mission based on existing U.S. and Russian launch vehicles and space station hardware. The 18-month mission would test a potential design for a piloted Mars transfer vehicle and demonstrate long-duration interplanetary flight and high-speed Earth-atmosphere reentry.
While close to Mars, the astronauts would take advantage of short radio signal travel time to teleoperate a rover on the planet. The rover would be launched to Mars on a separate launch vehicle ahead of the piloted flyby spacecraft. Teleoperations would enable planetary quarantine to be maintained until the debate over whether life exists on Mars could be resolved.
The second footstep in Landis's plan would be a piloted landing on Deimos. Landis noted that, with the possible exception of a few near-Earth asteroids, Mars's outer moon was the most accessible object beyond Earth orbit in terms of the amount of energy required to reach it. The mission would demonstrate Mars orbit insertion, Mars orbital operations, and Mars orbit departure. Deimos, Landis added, might contain water that could be split using electricity into hydrogen and oxygen, which could serve as chemical rocket propellants.
The third footstep was a piloted landing on Phobos, Mars's inner moon. "From Phobos," Landis declared, "the view of Mars will be spectacular." He proposed that an unmanned version of the piloted Mars lander be test-landed on Mars during the Phobos expedition. The lander might be used to collect a Mars surface sample and blast it back to Phobos for recovery by the astronauts and return to Earth laboratories for analysis.
Landis's fourth footstep would encompass several piloted Mars lander tests in Earth orbit and on the moon (incidentally returning Americans to the moon for the first time since Apollo 17 in December 1972). This would set the stage for the fifth footstep, a piloted landing during summer on one of Mars's polar ice caps.
Landis wrote that the martian ice caps contained readily accessible water that could be melted and split into hydrogen and oxygen propellants. In addition, the summer pole would receive continuous sunlight. Landis, a space power system engineer, noted that this would make highly efficient the use of electricity-generating solar arrays. Because the Sun would not set, the expedition would need neither batteries nor the extra solar arrays required to charge them for periods when the Sun was below the horizon.
The Mars temperate landing, the sixth footstep, would mark the culmination of Landis's program. Successfully accomplishing a landing in the martian mid-latitudes would, Landis predicted, result in budget cuts and Mars program cancellation within two years.
His seventh footstep was, thus, designed to postpone the inevitable. He argued that a landing in Valles Marineris, Mars's equatorial "Grand Canyon," would provide a spectacular coda exciting enough to forestall program cancellation.
Landis wrote that finding easily exploitable resources on Deimos, Phobos, and Mars might lower costs, enabling piloted Mars exploration to continue on "a shuttle-scale budget." He echoed science popularizer and planetary scientist Carl Sagan when he proposed that Mars replace the Cold War as a driver for Western aerospace, adding that the Soviet Union's collapse in 1991 had made available Russia - with its Energia heavy-lift rocket, Mir space station modules, and long-duration spaceflight experience - as a cooperative partner. Landis concluded by urging an immediate start to his Mars program, arguing that "despite indications, there is no better time to act."
"Footsteps to Mars: An Incremental Approach to Mars Exploration," Geoffrey Landis, Journal of the British Interplanetary Society, Vol. 48, September 1995, pp. 367-372; paper presented at The Case for Mars V conference in Boulder, Colorado, 26-29 May 1993