28 November 2016

Rube Goldberg's Space Shuttle

By mid-1971, this was one of the two leading Space Shuttle design configurations. The first stage, bearing the letters "USA" and a single stabilizing oversized tail fin, might have been derived from the Saturn V S-IC first stage. Image credit: NASA
For Americans above a certain age, the phrase "Rube Goldberg Machine" elicits a chuckle or perhaps a sneer, depending on the context of its use. Rube Goldberg (1883-1970) was an award-winning cartoonist. His most famous drawings were of whimsical machines that accomplished a simple task in the most complex way possible.

It is not too unkind, given that most of the factors that led to its complexity were outside of NASA's control, to place the Space Shuttle in the category of a Rube Goldberg Machine. It began as a simple idea - economically deliver crews, supplies, and equipment to an Earth-orbiting Space Station - and, through conflicting, expanding demands placed on it, unwise cuts in funding for its development, and deferral of the Space Station it was meant to serve, grew into something large, complex, and costly.

Throughout the Space Shuttle design process, NASA fought a rearguard action to preserve reusability. In 1969, the U.S. civilian space agency sought a fully reusable Shuttle design with a piloted Booster and a piloted Orbiter, each carrying liquid propellants for placing the Orbiter into Earth orbit. Inadequate funding support from the Nixon White House and Congress coupled with a U.S. Air Force requirement that the Orbiter include a payload bay at least 60 feet long and 15 feet wide soon made that design untenable, however.

NASA and its contractor teams took a rapid series of cost-cutting steps during 1970-1972. The design process became messy and almost untrackable, with concepts proposed, abandoned, and proposed again in rapid succession or even simultaneously by different contractor and NASA teams.

The piloted Booster shrank after engineers tacked a pair of reusable solid-propellant rocket motors onto its tail. Then it ceased to be piloted, becoming part of what amounted to a three-stage rocket. Riding bolted to the top or side of the Booster's expendable second stage, the piloted Orbiter became in effect a reusable third stage that would complete its climb to Earth orbit by burning liquid hydrogen (LH2) fuel and liquid oxygen (LOX) oxidizer carried in tanks inside its streamlined fuselage.

In part to prevent the Orbiter from growing out of all proportion as its payload bay grew, NASA moved low-density LH2 out of the Orbiter fuselage into cheap expendable drop tanks. The move also ended worries about safe containment within the Orbiter of volatile LH2, which is prone to slow seepage even through solid metal.

The Orbiter carried LOX for its ascent to orbit inside its fuselage for a little while longer. By August 1971, however, the delta-winged Orbiter contained only enough propellants to maneuver in orbit and to slow itself so that it could deorbit and reenter Earth's atmosphere. At first, its orbital maneuvering engines were expected to burn LH2/LOX, but then NASA substituted hypergolic (ignite-on-contact) propellants.

During the same period, the preferred Shuttle stack design flip-flopped between two candidates. One (image at top of post) had two LH2/LOX stages stacked one atop the other. The first-stage engines were mounted directly beneath their stage, as on a conventional rocket. The engines for the second stage were built into the tail of the Orbiter mounted on its side. They would ignite at altitude after the first stage separated and, owing to their position on the side of the second stage, would thrust off center.

The first stage would be reusable; after depleting its propellants and separating from the second stage, it would deploy parachutes and lower to a gentle landing at sea, where it would bob with its engines pointed at the sky. A specially designed ship would then recover it and tow it to port for refurbishment. The second stage would reach orbit attached to the Orbiter, then would separate, reenter, and break up over the ocean.

The other candidate design (image below) featured a reusable Orbiter and a pair of reusable LH2/LOX boosters mounted on the sides of a single large expendable External Tank (ET). The lightweight ET's interior would be split between a small tank for LOX and a large one for LH2. Both the twin boosters and the tail-mounted Orbiter engines would ignite on the launch pad. The side-mounted boosters would expend their propellants and fall away a couple of minutes after liftoff. They would each deploy parachutes and descend to a gentle ocean landing to await recovery. Pipes leading from the ET tanks would feed propellants to the Orbiter's engine cluster throughout ascent to orbit.

That looks familiar: the other Space Shuttle stack design leading the pack by mid-1971. Note off-center thrust plumes from the delta-winged Orbiter's tail-mounted engines (lower left). Image credit: NASA
In a final cost-cutting move, NASA replaced the reusable liquid-propellant boosters with reusable solid-propellant boosters. The liquid-propellant boosters could be turned off in the event of a major malfunction; the solid-propellant boosters could not.

Mounting engines on the reusable Orbiter meant that they would be returned to Earth for refurbishment and reuse. The resulting off-center thrust troubled many engineers, however, because it meant that thrust forces would be transmitted through the Orbiter to the second stage (in the case of the first Shuttle design alternative) or the ET (in the case of the second). This would place added stress on the Orbiter, its links to the second stage or ET, and the second stage or ET. Links between the second stage/ET and the Orbiter would include propellant pipe connections, which engineers expected would be prone to leaks even without the added stress of off-center thrust.

Off-center thrust also meant that the short LOX tank, when full the heaviest part of the second stage or ET, had to be situated atop the long LH2 tank, the lightest part of the second stage or ET. Putting the dense LOX on top helped the Shuttle stack to remain stable in flight as the Orbiter's engines rapidly emptied the second stage or ET and the stack's center of gravity shifted, but it also placed added stress on the second stage or ET structure. Because the LOX at the top of the second stage/ET needed a long pipe to reach the engines on the Orbiter's tail, the arrangement also increased the risk of propellant pipe rupture.

During the 1970-1972 Shuttle design evolution, several engineers proposed and re-proposed a novel alternative to off-center thrust: a cluster of reusable engines that would operate attached to the bottom of the expendable second stage or ET. After the Orbiter reached Earth orbit and its main engines shut down, the engine cluster would be detached from the second stage or ET and, using an armature system of booms or struts, be swung into a storage compartment inside the aft end of the Orbiter fuselage.

The second stage or ET would then be cast off. In the case of the ET, vented residual propellants would cause it to tumble, rapidly reenter the atmosphere, and break up. When the astronauts on board the Orbiter completed their mission in Earth orbit, the engine cluster would return to Earth with them, where it would be removed from the compartment, refurbished, and mounted on a new second stage or ET.

The NASA Manned Spacecraft Center – renamed the Lyndon B. Johnson Space Center (JSC) in February 1973 – managed Space Shuttle development. Shuttle engineers were quick to reject the swing-engine design. They did this mainly because its armature system seemed overly complex and thus prone to malfunctions.

The Rube Goldbergian swing-engine concept would not die, however. In March 1974, in fact, JSC chief of engineering Maxime Faget (co-designer of the Mercury capsule and a 1969 all-reusable Shuttle) and JSC engineers William Petynia and Willard Taub filed an application to patent the swing-engine design. By then, the decision to settle on the second stack configuration described above was two years old (NASA Administrator James Fletcher announced the choice on 16 March 1972).

The JSC engineers proposed three swing-engine design approaches. The U.S. Patent Office granted their patent on 30 December 1975.

All of their design approaches would, they argued, eliminate stress on the Shuttle stack caused by off-center thrust, enable transposition of the ET LOX and LH2 tanks, and improve stack flight characteristics during ascent through Earth's atmosphere. The results would include a lighter Orbiter and ET, more payload, and greater safety.

As a bonus, the swing-engine system would enable the Orbiter to adjust its center of gravity after it released or took on an orbital payload, thus improving its reentry and atmospheric gliding flight characteristics. It would do this by shifting the engine cluster forward toward the back of the Orbiter payload bay using the same mechanical armature system that would swing the engines away from the bottom of the ET. The armature system would also serve to gimbal (swivel) the engines to steer the Orbiter/ET stack during ascent to orbit.

Other benefits would spring from the swing-engine design. The ET and engine cluster could be tested together without an Orbiter attached. All piping linking the Orbiter and the ET would be eliminated. Separable links between the ET and the engine cluster would be required, of course. The engine cluster would, however, be quite small and light compared to the Orbiter; this meant that it could be easily mounted on the ET, tested for leaks, and (if necessary) removed and repaired before flight.

First method for transferring engine cluster from aft end of the ET to storage in the Orbiter aft fuselage. 1 = ET; 2A = mounting ring for four engines (in thrust position on ET); 2B = mounting ring for four engines (in stored position in Orbiter aft fuselage); 3 = joint linking lower armature to engine ring (1 of 2); 4 = lower armature strut (1 of 2); 5 = upper armature strut (1 of 2); 6 = joint linking upper armature to Orbiter aft fuselage (1 of 2); 7 = trailing edge of wing (1 of 2); 8 = opening in aft fuselage for engine cluster storage; 9 = solid-propellant ascent abort rocket (1 of 2); 10 = vertical stabilizer. Image credit: NASA/U.S. Patent Office
The JSC engineers' first swing-engine design, illustrated above, assumed a quartet of Shuttle engines, a single vertical stabilizer, and a door-shaped aft fuselage opening. The armature system would swing the engines into the fuselage so that their engine bells pointed aft.

The second design, illustrated below, assumed three Space Shuttle engines in a vertical row and an Orbiter with twin out-splayed vertical stabilizer fins. The armature system would swing the engines up and over the aft end of the Orbiter fuselage and lower them into a rectangular slot between the fins. After a horizontal landing on Earth, their engine bells would point skyward.

Second method for transferring the Space Shuttle engine cluster from the aft end of the ET to the storage space in the Orbiter aft fuselage. 1 = Orbiter payload bay; 2 = LOX tank in aft end of ET; 3 = ET; 4 = vertical stabilizer (1 of 2); 5A = engine cluster in thrust position on aft end of External Tank; 5B = engine cluster in stowed position in Orbiter aft fuselage; 6A = centerline of engine cluster in thrust position; 6B = centerline of engine cluster in stowed position; 7A = armature strut for transferring engine cluster (thrust position) (1 of 2); 7B = armature strut for transferring engine cluster (stowed position) (1 of 2); 8 = center armature joint (1 of 2); 9 = path of center armature joint (8) during engine cluster transfer to stowed position. Image credit: NASA/U.S. Patent Office
The JSC engineers' third swing-engine design also assumed three engines arranged in a vertical row, but could be used with either single or double vertical stabilizer Orbiter configurations. The armature system would tilt the engine cluster 45° and slide it on rails into a rear-facing opening in the aft fuselage. As with their second design, the engine bells would point upward after the Orbiter glided to a landing.

Orbital Flight Test-1 (OFT-1), also known as Space Transportation System-1 (STS-1), the first flight of the Space Shuttle. Columbia lifted off from Launch Complex 39A at Kennedy Space Center, Florida, on 12 April 1981, and landed at Edwards Air Force Base, California, two days later. Veteran astronaut John Young was Commander and rookie Robert Crippen was Pilot. Image credit: NASA
The swing-engine concept had, of course, become a mere curiosity well before the U.S. Patent Office granted Faget, Petynia, and Taub their December 1975 patent. Following the March 1972 selection of the Shuttle stack configuration, NASA awarded Rockwell International the contract to build Space Shuttle Orbiters on 26 July 1972. The company built a total of five space-worthy Orbiters, each with three Space Shuttle Main Engines mounted in a triangle on their aft fuselages, over a span of more than 20 years.

The Orbiters functioned admirably, though they needed far more costly refurbishment and maintenance than NASA envisioned when it proposed its all-reusable Space Shuttle design in 1968-1969. Booster system malfunctions claimed two Orbiters and their seven-person crews, however. Challenger was destroyed on 28 January 1986 when a solid-propellant booster joint burned through, leading to ET structural failure and Orbiter break-up 73 seconds after launch. Columbia, the first Orbiter to orbit Earth (12-14 April 1981), was lost after foam insulation on the ET it rode broke loose during ascent and struck and damaged its wing leading edge. This led to wing structural failure and Orbiter breakup during reentry on 1 February 2003, at the end of a 16-day mission.


Patent No. 3,929,306. Space Vehicle System, Maxime A. Faget, William W. Petynia, and Willard M. Taub, NASA Johnson Space Center, 5 March 1974 (filed), 30 December 1975 (granted)

Space Shuttle: The History of the National Space Transportation System, the First 100 Missions, Dennis R. Jenkins, 3rd Edition, 2008

Wikipedia: Rube Goldberg Machine - https://en.wikipedia.org/wiki/Rube_Goldberg_machine (accessed 28 November 2016)

More Information

George Landwehr von Pragenau's Quest for a Stronger, Safer, Better Space Shuttle

Series Development: A 1969 Plan to Merge Saturn V and Shuttle to Spread Out Space Program Cost

Where to Launch and Land the Space Shuttle? (1971-1972)

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

23 November 2016

An Apollo Landing Near the Great Ray Crater Tycho (1969)

Splat! Tycho crater (lower center) is the the most prominent bright surface feature in this NASA image of the full Moon. Linear rays originating at the crater can be traced outward for hundreds of kilometers.
Of the seven automated Surveyor spacecraft NASA launched to the Moon between May 1966 and January 1968, only the last, Surveyor 7, aimed for a target selected specifically for its scientific value. Surveyors 2 and 4 failed, while Surveyors 1, 3, 5, and 6 soft-landed at flat mare (basalt plain) sites in the "Apollo Zone," the near-equatorial band readily accessible to piloted Apollo Lunar Module (LM) spacecraft. The successful Apollo Zone Surveyors performed valuable scientific investigations, but their main purpose was to image their landing sites and test soil bearing strength to help assure mission planners that the lunar terrain was smooth and stable enough to permit Apollo astronauts to land safely.

Surveyor 7, by contrast, aimed for the rugged northern flank of Tycho crater, one of the most prominent features on the Moon's Earth-facing nearside hemisphere. The 85-kilometer-wide asteroid impact scar, centered at 43° south latitude in heavily cratered highlands terrain, is surrounded by an extensive system of bright rays best viewed when the Moon is full. The rays are made up of ejecta blasted out when Tycho formed about 110 million years ago. As ejecta fell back onto the Moon, it stirred up more material, generating a ray cascade extending up to 1500 kilometers from Tycho.

Surveyor 3 (above) served as a pinpoint landing target for Apollo 12 astronauts Charles Conrad and Alan Bean in November 1969. During their second Moonwalk, they stopped by the derelict lander to collect parts and take pictures for engineering analysis. Surveyor 7 resembled Surveyor 3, but included noticeable differences; most obvious was the addition of the deployable alpha-scattering instrument. Image Credit: NASA
Hand-laid mosaic of images from Surveyor 7 illustrating the rocky, rolling nature of the terrain north of Tycho. Image credit: NASA/USGS
Surveyor 7 lifted off from Cape Kennedy atop an Atlas-Centaur rocket on 7 January 1968. It landed on 10 January at 40.9° south latitude, 11.4° west longitude, just 2.5 kilometers from its intended target and 30 kilometers from Tycho's rim, on the ejecta blanket surrounding the crater. Less than an hour after touchdown, the three-legged solar-powered lander returned the first of more than 21,000 images it would beam to Earth. Some of these were stereo pairs, enabling scientists to precisely locate the many varied rocks and boulders visible in the field of view of Surveyor 7's scanning camera. Other images were assembled into panoramic mosaics that show lunar landscape features up to 13 kilometers away from the lander.

Among the features most intriguing to lunar scientists were so-called "lakes" of relatively dark material. They lay in depressions and had relatively flat surfaces. Curving, branching trenches etched many of these small dark plains. Some scientists interpreted the lakes as signs of recent volcanic activity, the "holy grail" of 1960s lunar exploration.

Tycho, its ejecta blanket, and the Surveyor 7 landing site as imaged and labeled by the Lunar Reconnaissance Orbiter Camera (LROC) team at Arizona State University (ASU). LROC is a multispectral imager on NASA's Lunar Reconnaissance Orbiter spacecraft, which entered lunar polar orbit in June 2009. The ejecta surrounding the crater partly covers and "blurs" lunar surface features that existed before Tycho was formed. Image credit: NASA/ASU
Surveyor 7 carried more scientific apparatus than any of its predecessors. Besides its camera, Surveyor 7 carried an alpha-scattering device for determining the composition of rocks and dirt and an arm-mounted digger. The former had flown previously on Surveyor 5 and Surveyor 6; the latter on Surveyor 3. At first, the alpha-scattering device failed to deploy, but flight controllers were able to direct the digger to push it down into contact with the lunar surface. They later used the arm/digger to position the alpha-scatterer on a rock and in a trench the digger had excavated. They found that the dirt at Surveyor 7's highlands landing site contained more aluminum than did dirt at the mare sites the other Surveyors explored.

Controllers were unable to place the alpha-scatterer in contact with boulders on a low ridge near Surveyor 7, some of which might have been blasted from kilometers below the lunar surface by the Tycho impact. They were far beyond the digger's 1.52-meter maximum reach. Nor were controllers able to move the instrument to the dark material of the lakes, the nearest of which lay about a kilometer from the lander. When the Surveyor 7 mission ended on 21 February 1968, much was known about its complex landing site, but much else remained mysterious.

Lunar Orbiter image of the Surveyor 7 landing area. The two dotted lines originating at the Surveyor 7 ("S.VII") touchdown point indicate the limits of the field of view of the lander's scanning camera. North is toward the top. Prominent in the right half of the image is a dark lake-like feature, the "shore" of which is located about a kilometer away from Surveyor 7. Image credit: NASA
The lakes and the tantalizing variety of rocks near Surveyor 7 caused some lunar scientists to call for an Apollo mission to the site. It was far outside the Apollo Zone, but could be reached during certain times of year if conservative Apollo mission design rules were relaxed.

In August 1969, less than a month after Apollo 11, the first piloted Moon landing mission, U.S. Geological Survey (USGS) scientists worked with Bellcomm, NASA's Apollo planning contractor, to rough out the surface portion of an Apollo Tycho mission. It would begin with a pinpoint LM landing a kilometer southeast of Surveyor 7.

The pinpoint landing would be required if the astronauts were to follow the geologic traverse routes the Bellcomm/USGS team planned. The LM descent stage would carry enough propellants to enable the Tycho mission crew to at least partly compensate if their LM missed its designated touchdown point. This was deemed an especially important capability because the Apollo 11 LM Eagle had landed off course at the edge of its landing ellipse.

On the basis of Surveyor 7 and Lunar Orbiter V images, the Bellcomm/USGS team judged that the Tycho site was too rocky for a jeep-like lunar rover to navigate. They suggested that the astronauts explore on foot within an operational radius of about 2.5 kilometers centered on their LM. Proposed new "constant volume" hard suits tougher and more flexible than the mostly fabric Apollo suits would, they anticipated, make possible speedy hikes over rugged terrain. The new suits would also permit the astronauts to operate on the surface for up to seven hours at a stretch. They would spend 54 hours at the Tycho landing site, providing enough time for three seven-hour traverses.

LROC image of the Surveyor 7 landing area. Please refer to the previous image for a scale bar. The arrow points to the derelict lander, which is just visible because of the shadow it casts on the surface. Technology advancement means that the image is sharper than the previous Lunar Orbiter image: individual boulders about the size of the lander are clearly seen, as are details of the lake-like melt "pond" and small impact craters. Image credit: NASA/ASU
The Bellcomm/USGS team planned that, during Traverse I, one astronaut would deploy an Apollo Lunar Scientific Experiment Package (ALSEP) about 1.1 kilometers east of the LM. The ALSEP would include a passive seismometer. In addition to establishing a "far southern" station in the Apollo seismic network, the instrument would exploit natural moonquakes and asteroid impacts to chart Tycho's subsurface structure. The ALSEP might also include a heat-flow experiment (to help scientists determine whether volcanism had occurred recently at the site), a laser retroreflector, a magnetometer, and a gravimeter.

The other astronaut, meanwhile, would walk along the low ridge visible from Surveyor 7 and sample the boulders there. The two Moonwalkers would then meet up and return to the vicinity of the LM. Traverse I would total about 3.5 kilometers.

During Traverse II, at about 6.25 kilometers the longest of the Tycho mission Moonwalks, the astronauts would strike north together to the "shore" of a prominent kilometer-wide dark lake. They would photograph and sample the branching trenches, then walk to a point 2.6 kilometers from their LM to sample "dark flow dome material." On the way back to the LM, they would visit Surveyor 7 to collect samples of lunar materials it had examined and salvage parts of the robot lander for engineering analysis.

The final traverse of the Apollo Tycho mission would see the astronauts walk south about 1.3 kilometers to sample another dark lake, then travel a further 1.4 kilometers to sample subsurface material exposed by a small fresh impact crater. They would then hike half a kilometer to a raised "flow levee" surrounded by "late smooth flow materials." Traverse III would total 5.25 kilometers. In all, the astronauts would walk 15 kilometers and collect between 100 and 200 pounds of samples during their three Moonwalks.

The Bellcomm/USGS team acknowledged that the Tycho site presented challenges beyond its position outside the Apollo Zone. It was rugged and undulating, so the astronauts were likely to lose line-of-sight contact with their LM's radio antennas as they walked. The LM would relay signals from their space suit radios, so they would temporarily lose radio contact with Earth. In addition, the site had not been imaged from orbit at the same high resolution as other candidate Apollo sites.

The team suggested that, if no high-resolution orbital images of the site could be obtained and if this continued to be considered a major drawback, then the Apollo Tycho mission could land closer to Surveyor 7, where the surface had been well characterized. This would, however, create its own problems. The most serious of these would be to place much of the Traverse III loop beyond the planned 2.5-kilometer operational radius of the mission's Moonwalks.

This map of the landing sites of all the successful Surveyors shows how far south Surveyor VII landed. No other spacecraft has soft-landed so far from the Moon's equator. Image credit: NASA
During 1970, in the aftermath of the near-disastrous Apollo 13 mission, NASA engineers, mission planners, managers, and astronauts, never enthusiastic about the Tycho site proposal, rejected the region as too rugged for a safe Apollo landing. Some scientists were, however, not easily deterred: they continued to sing the site's praises as late as 1972. They pointed to the fact that Surveyor 7 had successfully landed without the precise terminal guidance an astronaut would provide. They hoped that Apollo 16 or 17 might be diverted to Tycho. In the end, however, no Apollo mission visited Surveyor 7, leaving to it the honor of the highest-latitude/farthest-south landing site of any spacecraft that has soft-landed on the Moon.

The dark lake-like features observed near Tycho are known today to be patches of melt material that flowed and was thrown outward from Tycho during its explosive formation, not signs of recent volcanic activity. Impact melt flows are found inside and around many large young impact craters. Melt flow features are rare close to older craters because the steady rain of micrometeoroids and small asteroids that strikes the moon splinters them into Moon dust and boulders and gradually renders them indistinct.


Surveyor VII: A Preliminary Report, NASA SP-173, NASA Surveyor Program Office, May 1968

Surveyor Program Results, NASA SP-184, Surveyor Program, NASA, 1969

"Tycho - north rim," H. Masursky, G. Swann, D. Elston, and J. Slaybaugh, 14 August 1969 (revised 15 August 1969)

Memorandum, J. Slaybaugh to J. Llewellyn, "Tycho Rim Engineering Evaluation - Case 320," Bellcomm, Inc., 28 August 1969

To A Rocky Moon: A Geologists' History of Lunar Exploration, Don E. Wilhelms, The University of Arizona Press, 1993, pp. 242, 287, 312

More Information

"Essential Data": A 1963 Pitch to Expand NASA's Robotic Exploration Programs

If an Apollo Lunar Module Crashed on the Moon, Could NASA Investigate the Cause? (1967)

"A Continuing Aspect of Human Endeavor": Bellcomm's January 1968 Lunar Exploration Program

18 November 2016

"Essential Data": A 1963 Pitch to Expand NASA's Robotic Exploration Programs

The derelict Surveyor 3 lander (left) became a pin-point landing target for Apollo 12 in November 1969. Image credit: NASA
The Apollo Program dominated NASA in the 1960s. Its chief aim was to place a man on the moon ahead of the Soviet Union and before 1970. In December 1963, three of NASA's four approved robotic exploration programs – Ranger, Surveyor, and Lunar Orbiter - focused on the moon. The fourth, Mariner, aimed at Mars and Venus. Apollo requirements - the need to find safe landing sites and to understand lunar conditions well enough to design the Apollo Lunar Excursion Module lander - dominated the moon programs. Beating the Communists to Venus and Mars was a major motivator for Mariner. In short, Cold War geopolitics ruled, not scientific exploration.

On 2 December 1963, NASA Lunar and Planetary Program staffers briefed NASA top brass (Administrator James Webb, Deputy Administrator Hugh Dryden, and Associate Administrator Robert Seamans) with the aim of shifting NASA’s robotic program priorities toward science.

In his introductory presentation, Lunar and Planetary Program Director Oran Nicks solicited funding to enhance the four extant programs with new science-focused missions. He also sought funding to initiate the new Voyager Mars/Venus program.

Nicks reminded Webb, Dryden, and Seamans that Mariner II had scored an impressive first by flying past Venus in December 1962. He noted that, one year after achieving world's first successful planetary flyby, NASA's entire approved planetary program consisted of just two Mars flybys (Mariners III and IV, set for launch in November 1964). Mariner missions planned after 1964 were, he stressed, "not firm." He blamed funding cuts and persistent problems with the finicky cryogenic liquid hydrogen/liquid oxygen Centaur upper stage for this surprising failure to follow up on Mariner II's success. Nicks then turned the briefing over to his Lunar and Planetary Program managers.

By the time Ranger Program Manager N. William Cunningham stood before Webb, Dryden, and Seamans, Rangers I through V had failed. Ranger I (launched 23 August 1961) and Ranger II (launched 18 November 1961), "Block I" vehicles meant to gather data on micrometeoroids, radiation, solar plasma, and magnetic fields in high elliptical Earth orbit, had fallen victim to Atlas-Agena B rocket malfunctions, as had Ranger III (launched 26 January 1962), a Block II spacecraft meant to rough-land on the moon a spherical balsa-wood capsule bearing a seismometer. Ranger IV (launched 23 April 1962) and Ranger V (launched 18 October 1962), also Block IIs, had suffered electrical failures.

The Block II Ranger spacecraft with spherical balsa-wood "lunar capsule." The solid-propellant retrorocket was intended to ignite during the final seconds of the spacecraft's flight, slowing the capsule so that it could make a survivable rough landing on the moon. Image credit: NASA 
Cunningham began his presentation by telling Webb and his deputies that Ranger VI, a Block III spacecraft designed to snap photos of the moon while plummeting toward destructive impact, would launch in January 1964. He assured them that his engineers had made "many changes in. . .the spacecraft. . .in an effort to improve its chances for success."

Four Block IIIs (Rangers VI through IX) were expected to photograph the moon by August 1964, then six Block Vs (Rangers X through XV) would fly in 1965-1967. Cunningham noted that NASA planned to spend $92.5 million on Block V Rangers. Much like the Block IIs, Block V Rangers would attempt to rough-land capsules containing instruments, including possibly a TV system for beaming to Earth images from the moon's stark surface. Cunningham called the Block Vs "the only backup" the U.S. had in place for the Surveyor Program, then urged Webb and his lieutenants to add $50 million to the Block V Ranger development budget.

Surveyor 1 Atlas-Centaur rocket liftoff, 30 May 1966. The three-legged Surveyor soft-landed on 2 June 1966 within the Flamsteed Ring, an ancient crater mostly inundated by lava flows that formed the moon's Oceanus Procellarum. The lander returned data during lunar daylight periods, when its single solar panel could make electricity to operate its instruments and radio. Surveyor 1 outlasted its expected lifespan: contact was not lost until 7 January 1967. Image credit: NASA
Surveyor Program Manager Benjamin Milwitzky took the floor next. He told Webb, Dryden, and Seamans that his program's main purpose was to gather "essential data about the lunar surface. . .needed for manned landings." An Atlas-Centaur rocket would launch the first Surveyor soft-lander in 1965. Milwitzky reported that Surveyor had been intended to carry 300 pounds of science instruments, but that Centaur upper stage problems had forced a cut to between 70 and 100 pounds. He told them that, while the reduced payload would be adequate for scouting Apollo landing sites, many lunar science opportunities would have to be abandoned - unless NASA took action.

Milwitzky proposed that Surveyor's science payload be restored by adding the corrosive element fluorine to the Atlas rocket's liquid oxygen propellant. He urged Webb, Dryden, and Seamans to spend $40 million in 1964-1966 to develop this energetic oxidizer mix for the Atlas.

If they agreed to beef up the Atlas, then the first advanced science-focused Surveyor could fly in 1967. A typical advanced Surveyor lander might include a Radioisotope Thermoelectric Generator to provide its instruments with long-term electricity, a drill for subsurface sample collection, on board sample analysis gear, a geophysical probe that could be lowered down the drill bore hole, a seismometer, a mast-mounted TV system for imaging a large area around the lander in stereo, and a small rover for exploring the landing site and emplacing explosive seismic experiment packages a safe distance away from the lander.

Milwitzky ended his presentation by proposing that NASA increase the number of planned Surveyor missions from 17 to 29. He estimated that the 17-mission program would cost $425.5 million; adding 12 more missions would cost an additional $352 million.

Milwitzky then handed off to Lee Scherer, Lunar Orbiter Program Manager. Scherer began his presentation by reminding Webb and his deputies that Lunar Orbiter missions 1 through 5 had been approved for 1966-1967, and that Lunar Orbiters 6 through 10, while not yet formally approved, were planned for 1967-1968. Lunar Orbiter spacecraft would, he said, aim "to obtain, initially, scientific data about the moon and its environment of special importance to the Apollo mission." The approved Lunar Orbiters were intended mainly to photograph areas of the lunar surface accessible to Apollo spacecraft (that is, close to the equator on the Nearside, the lunar hemisphere that forever faces Earth).

Scherer proposed that NASA fly five science-oriented Lunar Orbiters in 1968-1969. These might enter orbits inclined to the lunar equator, enabling them to pass over scientifically interesting surface features beyond the equatorial Apollo landing zone. They might also enter lunar polar orbit for whole-moon mapping. Gamma-ray spectrometers and infrared sensors might be used to map lunar mineralogy. Scherer also proposed a mission dedicated to exploring moon/Sun plasma interactions and any lunar magnetic field that might exist. Lunar Orbiters 1 through 10 would cost $198 million; Scherer estimated that adding Lunar Orbiters 11 through 15 would boost the program's cost by $95 million.

The Jet Propulsion Laboratory (JPL) in Pasadena, California, first proposed the ambitious Voyager Mars/Venus robotic spacecraft series in 1960. In December 1963, Voyager was not yet an approved NASA program, though studies continued at JPL and NASA Headquarters. According to Donald Hearth, the Lunar and Planetary Program Office staffer responsible for Voyager, NASA had allotted $7.1 million for Voyager studies in 1962-1963. Of this, all but $1.3 million had been shifted to cover funding shortfalls in other programs.

The Voyager spacecraft design as of mid-1967. The lander, bundled up in a conical black Mars atmosphere entry capsule and a back-shell, is visible on the spacecraft at upper right. Solar arrays form a flat ring around Voyager's protruding rocket motors and a skeletal high-gain radio antenna points toward Earth. Image credit: NASA
Assuming that Congress approved its development, the Voyager spacecraft would comprise three parts: a 2000-pound orbiter with a 2000-pound retro stage and a 2500-pound lander. These would leave Earth together on a two-stage Apollo Saturn IB rocket augmented by a Centaur third stage. For Mars missions, the Voyager lander would separate from its orbiter during approach to the planet, enter the atmosphere directly from its interplanetary trajectory, and land within 500 kilometers of a target site. It would explore its landing site for six months. After lander separation, the Voyager orbiter would fire the retro stage to slow down so that Mars's gravity could capture it into orbit.

Hearth told Webb, Dryden, and Seamans that the Voyager 1969 Mars lander would carry an impressive suite of 38 science instruments, including two TV cameras, a sample-collection drill, biology detectors, a microscope, a seismometer, a microphone, and meteorology sensors. Voyager 1969 Mars orbiter instruments would include multicolor stereo TV cameras, an infrared spectrometer for determining surface composition over wide areas, a magnetometer for charting the martian magnetic field, a cosmic dust detector, and a solar X-ray detector.

Though more capable than any other U.S. lunar or planetary spacecraft, the Saturn IB/Centaur-launched Voyagers would pale next to planned Saturn V-launched Advanced Voyagers. Hearth reported that the Saturn V rocket could launch to Mars a 3100-pound orbiter and one or more direct-entry landers weighing a total of 33,000 pounds.

These "large lander laboratories" might include rovers, balloons, and hovercraft to enable exploration beyond their landing sites. Alternately, the Advanced Voyager orbiter might carry a large retro stage that would enable it to retain its lander until after it achieved Mars orbit. Lander descent from Mars orbit would improve landing accuracy, Hearth explained.

Hearth estimated that the Voyager Program would cost $2.9 billion over 11 years. Assuming timely approval, NASA could launch Voyager test flights in 1967 and 1968, Voyager Mars missions in 1969, 1971, and 1973, Voyager Venus missions in 1970 and 1972, and Advanced Voyager Mars missions in 1973 and 1975.

Within a week of the 2 December 1963 briefing, James Webb informed Oran Nicks that NASA could not afford to expand its robotic lunar and planetary programs in support of science. In fact, by 13 December, when NASA Associate Administrator for Space Sciences and Applications Homer Newell announced that the Block V Ranger development was cancelled, it had become clear that NASA would cut back its robotic lunar programs, sharply limiting opportunities for science-focused missions. Ranger, Surveyor, and Lunar Orbiter became victims of their own success; almost as soon as they proved themselves to be capable scientific exploration machines by providing the data Apollo engineers and planners needed, NASA top brass opted to end them and move on.

In all, scientists were granted just four robotic missions specifically for scientific lunar exploration. Though Ranger VI was an embarrassing failure, Rangers VII and VIII succeeded, and the program concluded with the successful science-focused Ranger IX mission to Alphonsus crater in March 1965. All were Block III spacecraft. Five Lunar Orbiters mapped the moon between August 1966 and January 1968. Lunar Orbiters 4 and 5 were science-focused missions in a near-polar lunar orbits. Surveyor ended with its seventh flight, a science-focused mission to a site just north of the bright ray crater Tycho in January 1968.

After Apollo, NASA received data from instruments left behind on the moon by the Apollo astronauts. These were turned off in September 1977. The U.S. civilian space agency then largely abandoned the moon, scene of its greatest triumph, until 1994, when it conducted the Clementine mission in cooperation with the Department of Defense Ballistic Missile Defense Organization. Clementine, a technology test-bed, orbited the moon for about 10 weeks. It shared little or no design heritage with earlier NASA lunar spacecraft.

Mariner 9 carried a large propellant supply (hidden beneath the white cover) so that it could slow down and capture into Mars orbit. It left Earth on an Atlas-Centaur rocket on 30 May 1971 and became the world's first planetary orbiter on 14 November 1971. Image credit: NASA
Mariner 10 left Earth on 3 November 1973 and flew past Venus on 5 February 1974. Using Venus's gravity and orbital motion, it performed the world's first gravity-assist planetary flyby. This placed it on course for a trio of Mercury flybys in 1974-1975. Image credit: NASA
The 1960s and 1970s saw a total of seven successful Mariners and four successful Mariner-derived planetary spacecraft. In July 1965, Mariner IV became the first spacecraft to fly past Mars. No Mariner ever carried an atmosphere probe, but Mariner 9 (May 1971-October 1972) became the first Mars orbiter (and, indeed, the first planetary orbiter in history). Mariner 10, officially the last spacecraft of the Mariner series, became the first to fly past Mercury (in fact, it flew by the planet three times, in March 1974, September 1974, and March 1975).

Voyager became an official NASA program in 1965, just in time to see its design scrapped and its estimated cost nearly doubled. Mariner IV was the culprit: it revealed that the planet's atmosphere was 10 times thinner than expected. Because of this, Voyager would need heavy landing rockets in addition to parachutes.

The star-crossed program lingered on until August 1967, when Congress refused to fund its continued development. NASA then proposed a cut-price Mariner-derived Mars landing program, called Viking, which received approval in 1968 from a Congress increasingly aware of Soviet claims of plans to explore the Solar System with automated rovers and sample-returners . Two Viking orbiter-lander pairs explored Mars beginning in 1976. The name Voyager was subsequently resurrected for twin Mariner-derived outer planets flyby spacecraft - originally named Mariner Jupiter-Saturn - which departed Earth in 1977.

Viking Orbiter 1 releases Viking Lander 1 in Mars orbit, 20 July 1976. The Lander (below) is stowed inside an aeroshell; a bioshell for protecting the Lander from terrestrial contamination after it was sterilized remains attached to the Orbiter, which resembles Mariner 9. Image credit: NASA
Of all the Mariner-derived spacecraft launched, only the most distant remain functional. Voyager 1 flew past Jupiter (1979) and Saturn (1980); Voyager 2 conducted a grand tour of Jupiter (1979), Saturn (1981), Uranus (1986), and Neptune (1989). At this writing, Voyager 1 is located 137.6 Astronomical Units (AU) from Earth, while Voyager 2 is 113.3 AU from Earth. (An AU, the distance from the Sun's center to the Earth's center, iapproximately 149.6 million kilometers.) Image credit: NASA


"Briefing for the Administrator on Possible Expansion of Lunar and Planetary Programs," NASA Headquarters, 2 December 1963

Astronautics and Aeronautics, 1963, NASA SP-4004, 1964, p. 477

Lunar Impact: A History of Project Ranger, NASA SP-4210, R. Cargill Hall, NASA, 1977

The Voyage of Mariner 10: Mission to Venus and Mercury, NASA SP-424, James A Dunne & Eric Burgess, NASA, 1978

On Mars: Exploration of the Red Planet, 1958-1978, NASA SP-4212, Edward Clinton Ezell & Linda Neuman Ezell, NASA, 1984

Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, NASA SP-2002-4524, Monographs in Aerospace History Number 24, Asif A. Siddiqi, 2002, pp. 88-90, 105-106, 110-112

Voyager: The Interstellar Mission - http://voyager.jpl.nasa.gov/ (accessed 19 November 2016)

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08 November 2016

One-Man Space Station (1960)

Final Mercury: the black Mercury-Atlas 9 spacecraft and its gleaming Atlas booster rocket in October 1963. Image credit: NASA
Probably the prize for "smallest space station design ever proposed" should go to McDonnell Aircraft's One-Man Space Station. On 24 August 1960, engineers with St. Louis-based McDonnell, the Mercury spacecraft prime contractor, described the mini-station to members of the Space Task Group (STG) at NASA's Langley Research Center in Hampton, Virginia.

A 10-foot-long, six-foot-wide pressurized cylinder with dome-shaped ends, the One-Man Space Station was meant to be launched stacked between a single-seat Mercury on top and an Agena-B upper stage below. The assemblage would be launched atop an Atlas-D rocket similar to that tapped to launch standard Mercury-only orbital missions.

The Atlas-Agena rocket was an early workhorse of lunar and planetary exploration. This image shows the launch of the Mariner 1 Venus probe on 22 July 1962. Less than five minutes later, the Atlas first stage veered off course. The range safety officer transmitted a self-destruct command and the Atlas, Agena upper stage, and Mariner 1 were destroyed. Image credit: NASA
One might be excused for calling the One-Man Space Station a mission module that enhanced Mercury spacecraft capabilities rather than a bona fide space station. It was meant to be occupied for just 14 days by the single astronaut launched with it in the Mercury spacecraft, then permanently abandoned when the astronaut separated from it in the Mercury to return to Earth.

The group of NASA engineers that heard McDonnell's presentation shared some traits with the proposed One-Man Space Station: it was small and meant to be only temporary. The STG was founded on 5 November 1958, a little more than a month after NASA opened for business. Based at NASA's Langley Research Center in Hampton, Virginia, the STG's aim was to carry out Project Mercury, the U.S. effort to launch a man into space ahead of the Soviet Union.

Though President Dwight Eisenhower took a dim view of what he saw as "space stunts" - for example, launching men into space - he became, along with Senate Majority Leader Lyndon Baines Johnson, one of NASA's chief architects. Eisenhower made no commitment to piloted spaceflight after Mercury. He insisted that Mercury be conducted as a civilian program to keep it separate from the serious military business of developing battlefield and intercontinental missiles and launching reconnaissance and early-warning satellites.

Atlas-D - a modified intercontinental ballistic missile - was not by itself powerful enough to place the Mercury/One-Man Station/Agena-B combination into Earth orbit. McDonnell proposed that the General Dynamics-built Agena-B ignite after the Atlas-D exhausted its propellants and separated. The Agena-B would then insert itself, the Mercury, and the One-Man Space Station into a 150-nautical-mile-high orbit inclined 30° relative to Earth's equator. The Agena-B would remain attached after orbit insertion: it was restartable and would retain enough propellants to maneuver in Earth orbit.

It is probable that the One-Man Space Station was the civilian version of a proposed piloted spy satellite. With its integral Agena-B stage for Earth-orbit injection and orbital maneuvers and its separable Mercury spacecraft for Earth return, McDonnell's station outwardly resembled the Discoverer automated satellites, the first of which was launched in January 1959. "Discoverer" was a cover name for the Corona spy satellite series. Atlas-launched Discoverer/Corona satellites employed an integral Agena for Earth-orbit injection and orbital maneuvers and a reentry capsule for exposed film return. An aircraft would capture the capsule as it descended on a parachute.

A piloted spy satellite must have seemed attractive by the summer of 1960, for the Discoverer/Corona program had suffered failure after failure. Not until Discoverer 14 - launched on 18 August 1960, just six days before McDonnell's presentation to the STG - did the program succeed in returning to Earth a capsule containing exposed film showing Earth-surface targets.

The One-Man Space Station's hull would encompass a total of 282 cubic feet of pressurized volume, of which 182 cubic feet would constitute living and working space. The astronaut would work inside the station in shirt-sleeves, not a pressure suit. A "laboratory test payload" - a suite of experiments which could be changed from flight to flight - would take up 40 cubic feet of the interior volume, while support equipment - for example, fuel cells capable of producing up to 1500 watts of electricity - would take up 60 cubic feet at the domed bottom end of the station.

Schematic of the "Tunnel Access" One-Man Station design with a human figure for scale. A = Mercury spacecraft; B = adapters for linking (from top to bottom) the Mercury spacecraft and the One-Man Space Station, the One-Man Space Station and the Agena stage, and the Agena stage and the top of the Atlas booster; C = inflatable tunnel linking the Mercury hatch with a similar hatch on the One-Man Space Station; D = pressurized work area; E = life support and electricity-generating equipment; F = One-Man Space Station laboratory test payload; G = Agena-B stage; H = Tunnel Access cover in launch position; I = Tunnel Access cover in deployed position; J = top of the Atlas-D rocket. Image credit: McDonnell Aircraft/David S. F. Portree
McDonnell proposed two possible designs for its One-Man Space Station. The method the astronaut would use to move between the attached Mercury spacecraft and the One-Man Space Station pressurized volume would distinguish the two designs. McDonnell dubbed them "Tunnel Access" and "Hinged Lab."

Tunnel Access would need fewer Mercury spacecraft modifications than Hinged Lab. An inflatable fabric tunnel would reach Earth orbit folded against the Mercury and One-Man Space Station under a streamlined metal cover. Upon reaching orbit, the astronaut would inflate the tunnel to create a passage between the standard-design 24-inch Mercury side hatch and a 24-inch hatch on the Station's side. The metal cover would remain attached to the tunnel to stiffen it and partly shield it from meteoroid punctures.

When time came to return to Earth, the astronaut on board the Tunnel Access Station would don his protective pressure suit, return to his cramped seat in the Mercury spacecraft, seal the Mercury hatch, and fire pyrotechnic bolts or cord to sever the inflatable tunnel. He would then separate his Mercury spacecraft from an adapter linking it to the Station, turn it so that its broad aft end faced in its direction of motion, and ignite a single solid-propellant retrograde motor to begin atmosphere reentry.

The Hinged Lab design would see the Mercury spacecraft swing on a hinge so that a modified Mercury side hatch could link up with a hatch on the side of the One-Man Space Station. When time came to return to Earth, the astronaut would seal the Mercury hatch, then swing his spacecraft back to its Earth launch position on top of the Station. He would fire explosive bolts to separate the Mercury from the hinged adapter, then would begin reentry.

"Hinged Lab" One-Man Space Station. A = hinge; B = ring-shaped adapter; C = transfer tunnel linking modified Mercury spacecraft hatch with One-Man Space Station hatch. Image credit: McDonnell Aircraft/David S. F. Portree
The presence of the Agena-B stage permitted McDonnell to delete the standard Mercury 24-pound solid-propellant posigrade motor set, which in Mercury-only flights would ignite to propel the spacecraft away from its spent Redstone or Atlas booster. Other modifications would include the aforementioned revised hatch designs, which would add 16 pounds to both the Tunnel Access and Hinged Lab One-Man Space Station designs; deletion of the astronaut-monitoring camera from the standard Mercury telemetry & recording system (a savings of 28 pounds); storage space in the Mercury spacecraft cabin for returning to Earth 28 pounds of experiment results generated on board the Station; and addition of seven pounds of water to the Mercury environmental control system.

A new-design adapter would link the broad base of the Mercury spacecraft with the top of the One-Man Space Station. This would weigh 97 pounds for the Tunnel Access design, which could get by with a relatively simple adapter, and 129 pounds for the more complex Hinged Lab adapter.

The Tunnel Access One-Man Space Station without Mercury and Agena-B would weigh 3344 pounds; for the Hinged Lab Station, the weight total was 3309 pounds. The Hinged Lab Station would include an additional 22 pounds of attitude-control propellant - necessary because of the difficulty of stabilizing the out-of-balance side-mounted Mercury configuration. The Tunnel Access Station, for its part, would add 50 pounds for the inflatable tunnel cover and 135 pounds for the tunnel itself.

McDonnell told the STG that the Atlas-D/Agena-B combination could inject 6076 pounds into the One-Man Space Station's planned orbit. Subtracting the combined weight of the modified Mercury, Agena-B, and Station left 1234 pounds for experiment equipment on the Tunnel Access Station and 1342 pounds on the Hinged Lab Station. The company listed as possible One-Man Space Station research projects the study of human adaptation to 14-day weightless missions; monitoring of "long-time equipment performance" on board spacecraft; "lunar probe navigation equipment" testing; radiation, geophysical, and astrophysical measurements; and, by using the Agena-B rocket motor, development of orbital rendezvous techniques.

McDonnell suggested that One-Man Space Stations might also be devoted to single-purpose missions: for example, one might be equipped to carry out communications research, the next might serve as an astronomical observatory, and yet another might enable detailed observations of Earth's weather. The company also suggested that a One-Man Space Station might revert to its likely original purpose: that is, high-resolution imaging of objects on Earth's surface.


One Man Space Station, McDonnell Aircraft, 24 August 1960

NASA's Origins and the Dawn of the Space Age, Monographs in Aerospace History #10, David S. F. Portree, NASA History Office, September 1998

More Information

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A True Gateway: Robert Gilruth's June 1968 Space Station Presentation

Re-Purposing Mercury: Recoverable Space Observatory (1964)

Space Station Gemini (1962)