Making Rocket Propellants from Martian Air (1978)

Water frost on Utopia Planitia as imaged by the Viking 2 lander. The horizon appears tilted because Viking 2 alighted with one of its three foot pads on a large rock. Image credit: NASA.

In the late 1970s, through the initiative of its director, Bruce Murray, the Jet Propulsion Laboratory (JPL) studied a range of possible Mars missions, including Mars Sample Return (MSR). Murray and others at the Pasadena, California-based lab were aware that funds for new Mars missions would be hard to come by; the U.S. economy was under strain and NASA, JPL's main customer, was devoting most of its resources to developing the Space Shuttle.

In addition, equivocal data from the astrobiology experiments on the twin Vikings, the first successful Mars landers, had been interpreted as negative, helping to damp public enthusiasm for the Red Planet. Would-be Mars explorers reasoned that, if an MSR mission would stand a chance of being accepted, then they would need to find technologies and techniques that could dramatically cut its anticipated cost.

In July-August 1978, two years after the Vikings landed and looked for life on Mars, three engineers at JPL — Robert Ash, a visiting faculty fellow from Old Dominion University in Virginia, and JPL staffers William Dowler and Giulio Varsi — reported on a small study they had conducted of one such cost-saving technology: specifically, making MSR Earth-return rocket propellants from martian resources. Using Earth-return propellants made on Mars would greatly reduce the mass of the MSR spacecraft at launch from Earth, permitting it to be launched on a small, relatively cheap launch vehicle.

Earlier researchers had proposed using Mars resources to make rocket propellants, but Ash, Dowler, and Varsi were the first to base their study on data collected by spacecraft on and in orbit of Mars. The Viking landers had confirmed that martian air is made up almost entirely of carbon dioxide, and had found that the planet's rusty red dirt contains an appreciable amount of water. The Viking 2 lander, at rest on the northern plain of Utopia Planitia, had imaged water frost on the surface in winter (image at top of post). In addition, the twin Viking orbiters had imaged water ice clouds high in the atmosphere and polygonal terrain resembling that found in near-polar permafrost regions on Earth.

Ash, Dowler, and Varsi examined three propellant combinations that would exploit resources the Vikings had found on Mars. The first, carbon monoxide fuel and oxygen oxidizer, could be produced by splitting ubiquitous martian atmospheric carbon dioxide. They rejected this combination, however; while easy to produce, it could yield only mediocre performance.

Hydrogen/oxygen, on the other hand, was a high-performance propellant combination with more than three times the propulsive energy of carbon monoxide/oxygen. It could be produced by collecting and electrolyzing (splitting) martian water, but Ash, Dowler, and Varsi rejected the combination because a heavy, electricity-hungry cooling system would be needed to keep the hydrogen in usable liquid form. This requirement would, they estimated, negate the mass-savings of making Earth-return propellants on Mars.

The third combination they examined was methane/oxygen, which could be produced on Mars using a process discovered in 1897 by Nobel Prize-winning chemist Paul Sabatier. Combining a small amount of hydrogen brought from Earth with martian atmospheric carbon dioxide in the presence of a nickel or ruthenium catalyst would yield methane and water.

The methane would be pumped to the MSR Earth-return rocket stage fuel tank and the water would be split using electricity to produce oxygen and hydrogen. The oxygen would be pumped to the MSR Earth-return oxidizer tank and the hydrogen would be reacted with more martian atmospheric carbon dioxide to produce more methane and water.

Ash, Dowler, and Varsi favored methane/oxygen because it would provide 80% of hydrogen/oxygen's propulsive energy, and because methane remains in liquid form at typical martian surface temperatures. They estimated that launching a one-kilogram Mars sample directly to Earth (that is, with no stop in Mars orbit to rendezvous with and transfer the sample to a Earth-fueled Earth Return Vehicle) would require manufacture of 3780 kilograms of methane/oxygen, and calculated that a Mars surface stay-time of at least 400 days would be necessary to allow sufficient time to manufacture adequate quantities of propellants.

The 1978 JPL study would inspire many other mission designers to tap resources the twin Vikings had confirmed exist on Mars. At the 1982 AIAA/AAS Astrodynamics conference, for example, Science Applications Incorporated engineers presented a paper on use of Mars resources to make propellants for automated rocket-propelled ballistic hoppers and propeller-driven airplanes. The Mars base scenario developed at the second The Case for Mars Conference (1984) relied heavily on extraction of resources from the martian atmosphere for both life-support consumables and rocket propellants.

Conceptual design of a large system for extracting propellants and life-support consumables from martian air. Image credit: C. Emmart/Boulder Center for Science and Policy.

"Feasibility of Rocket Propellant Production on Mars," R. L. Ash, W. L. Dowler, and G. Varsi, Acta Astronautica, Vol. 5, July-August 1978, pp. 705-724.

"In Situ Propellant Production: The Key to Global Surface Exploration of Mars?" AIAA-82-1477, S. Hoffman, J. Niehoff, M. Stancati; paper presented at the AIAA/AAS Astrodynamics Conference in San Diego, California, 9-11 August 1982.

The Case for Mars: Concept Development of a Mars Research Station, JPL Publication 86-28, NASA Jet Propulsion Laboratory, 15 April 1986.

More Information

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North American Aviation's 1965 Plan to Rescue Apollo Astronauts Stranded in Lunar Orbit

Apollo 15 Command and Service Module Endeavour in lunar orbit. The drum-shaped portion is the Service Module and the conical portion is the Command Module. Note the Service Propulsion System rocket engine bell at upper left and the extended probe docking unit at lower right. Image credit: NASA.

North American Aviation (NAA) became the prime contractor for the Apollo Command and Service Module (CSM) spacecraft on 28 November 1961. In July of the following year, the company received the unwelcome news that its spacecraft would not land on the Moon. NASA had favored the Lunar-Orbit Rendezvous (LOR) mode for carrying out Apollo landings over Direct-Ascent or Earth-Orbit Rendezvous, both of which would have seen the CSM reach the lunar surface.

LOR made the CSM a lunar orbiter and spawned a new spacecraft: the Lunar Excursion Module (LEM) lander. The LEM, later redesignated the Lunar Module (LM - pronounced "lem"), would transport two astronauts from the CSM in lunar orbit to a landing site on the Moon's surface and back again. The LEM comprised a descent stage with landing legs and a throttleable rocket engine and an ascent stage with a pressurized crew cabin, flight controls, a rocket engine, and a concave drogue docking unit on its roof.

LOR meant that NASA needed to develop the technologies and techniques of rendezvous and docking in lunar orbit. The LEM ascent stage would use the descent stage as a launch pad and climb to a low lunar orbit. The CSM would then move in, extend the active probe docking unit on its nose, and dock with the passive drogue on the LEM.

After the LEM crew transferred back to the CSM, the ascent stage would be cast off. The CSM would subsequently ignite its large Service Propulsion System (SPS) main engine to escape lunar orbit and begin the fall back to Earth.

This image of the Apollo 16 Lunar Module Orion shows clearly the separation plane between the descent and ascent stages. The former has legs, a ladder, and is covered with black paint and gold-colored multilayer blankets for thermal control; the latter is silver and black and has four attitude-control thruster quads (two are readily visible), a crew hatch (square with rounded corners), and a pair of triangular windows. Image credit: NASA. 

In December 1965, NAA's engineers briefed the NASA Headquarters Office of Manned Space Flight (OMSF) and Bellcomm, the space agency's Apollo planning contractor, on results of a preliminary feasibility study of a one-person CSM mission to rescue Apollo astronauts stranded in lunar orbit. The NAA engineers did not describe specific lunar-orbit rescue scenarios, though the CSM modifications they outlined offer clues about the types of rescue missions they envisioned.

The most important piece of rescue hardware they proposed was a special docking adapter ring installed on the rescue CSM's nose. Either an active probe or an active drogue could be mounted on the ring, so the rescue CSM could dock with either a LEM or a CSM. The lone rescue CSM astronaut could reconfigure the docking unit during the flight from the Earth to the Moon; this would permit adaptation to changing circumstances in lunar orbit.

NAA anticipated that a lunar-orbit rescue might require spacewalks, so provided the rescue CSM pilot with a tether and a life-support umbilical extension, a cold gas-propelled hand-held maneuvering device, and a protective "meteoroid garment" of the type Apollo astronauts would wear over their suits on the lunar surface. In addition, the rescue CSM would carry an Expandable Structures Space Rescue System (ESSRS) device. ESSRS was an inflatable "pole" meant to serve as a handrail for astronauts spacewalking between two spacecraft.

Other rescue CSM modifications would include new crew couches to accommodate up to four astronauts, a fourth umbilical so that all could link their suits to the rescue CSM's life support system, added breathing oxygen, a dish-shaped LEM docking radar antenna on an extendable boom, and new rendezvous and docking computer software. Modifications and additions would add a total of 445 pounds to the rescue CSM's weight. Removal of science equipment and other systems not required to rescue and return to Earth a crew stranded in lunar orbit would, however, reduce the rescue CSM's weight by 415 pounds, for a net weight gain of only 30 pounds.

Rescue CSMs would be advanced Block II spacecraft of the type earmarked for Apollo lunar missions. In late 1965, NAA expected to build a total of six Block I and Block II CSMs per year beginning in late 1966. Block I CSMs would be used in Apollo testing and Apollo Extension System (AES) Earth-orbital missions. AES, a proposed program intended to apply Apollo hardware to new missions, became a predecessor to the Apollo Applications Program, which subsequently evolved into the Earth-orbital Skylab Program. In the event, only Block II CSMs carried astronauts; work on Block I CSMs ceased following the deadly AS-204 (Apollo 1) fire of 27 January 1967.

NAA offered two plans for providing rescue CSMs for the Apollo Program. The first, Rescue Vehicle Program "A," would see CSM-110 and CSM-113 converted into rescue CSMs; that is, diverted from lunar exploration missions. They would be flight-ready in early 1969 and mid-1969, respectively. Starting in mid-1970, one of the lunar CSMs NAA produced annually would be built as a rescue CSM; the first of these would be designated CSM-119.

Rescue Vehicle Program "B" would see NAA produce nine CSMs per year. The company's representatives told NASA that this approach would guarantee "non-interference with basic Apollo or AES." The first rescue CSM of Program "B," designated CSM R-1, would be ready for flight at the end of 1968, between AES CSM-109 and lunar CSM-110. Program "B" rescue CSMs R-2, R-3, and R-4 would be completed in mid-1969, early 1970, and late 1970, respectively.

NAA assumed that during every Apollo lunar mission a rescue CSM would stand by atop a three-stage Saturn V rocket on one of the two Launch Complex (LC) 39 pads at Kennedy Space Center (KSC), Florida. The lunar mission would launch from the other LC 39 pad.

The rescue CSM Saturn V would be outwardly nearly identical to the lunar mission Saturn V. The rescue rocket would, however, carry no LEM in the tapered Spacecraft Launch Adapter shroud that would link the aft end of the rescue CSM to the ring-shaped Instrument Unit atop the Saturn V S-IVB third stage. In addition, the Boost Protective Cover that protected the conical Command Module during the first part of ascent would need to be modified slightly to make room for the special docking ring.

On the launch pad, the Saturn V rocket bearing the rescue CSM would have appeared nearly identical to one bearing a lunar landing mission CSM Saturn V. The Boost Protective Cover, visible near the top of the image, would have had a slightly more bulbous nose. Internally, the most significant difference would have been the lack of a Lunar Module within the segmented Spacecraft Launch Adapter, the white tapered housing linking the bottom of the CSM to the ring-shaped Instrument Unit on top of the Saturn V S-IVB third stage. Image credit: NASA. 

The rescue CSM and Saturn V would stand by on the launch pad until the Apollo lunar landing mission CSM safely departed lunar orbit and began its fall back to Earth, then would be rolled back to KSC's cavernous Vertical Assembly Building for storage until the next Apollo lunar mission. A single rescue CSM could be prepared for flight three times and mothballed twice; this meant that it could stand by during three lunar missions, then would need to be replaced.

NAA did not explain what would be done with unused rescue CSMs; presumably they would be scrapped, though perhaps some systems could be salvaged for use in other CSMs. Neither did the company explain what would happen to unused rescue Saturn V rockets.

The company assumed that in most cases the rescue CSM would launch immediately after NASA learned that a crew had become stranded in lunar orbit. Because it would not wait, in most cases it would not be able to rely on Earth launch geometry to help it to match orbits and carry out a rendezvous with the stranded spacecraft.

NAA determined that launching the rescue CSM immediately could create complications. It might, for example, increase the rescue mission's duration. NAA calculated that the time needed to reach a spacecraft stranded in lunar orbit and return to Earth could in fact exceed the Block II CSM's anticipated 240-hour (10-day) operational lifetime by up to 52 hours in the worst case. NAA recommended that NASA delay the rescue CSM's launch until launch geometry could ensure that its mission duration would not exceed 10 days.

When the rescue CSM reached the Moon's vicinity, it would ignite its SPS main engine to place itself into an elliptical "catch up" lunar orbit. At apolune (lunar orbit high point), the pilot could ignite the SPS again to line up the rescue CSM's orbital plane with that of the stranded CSM. At perilune (lunar orbit low point), the pilot would fire the SPS a third time to lower the rescue CSM's apolune, circularizing its orbit and placing it near the stranded spacecraft.

NAA estimated that Rescue Vehicle Program "A" would add a total of $86 million to the cost of the Apollo Program per year. An 18-month program of development and testing would cost $50 million, $6 million would pay for modifications to two Apollo lunar CSMs, and four new rescue CSMs would cost $38 million each. The company provided no cost estimate for its Rescue Vehicle Program "B."

The NAA engineers did not discuss how astronauts stranded in lunar orbit might eke out their limited supplies of consumables — for example, breathing oxygen — while they awaited rescue. This would be particularly worrisome in the case of a LEM stranded in lunar orbit by a catastrophic CSM failure, for at the time of the NAA study the LEM was expected to keep two astronauts alive for at most one or two days. Neither did they assess the risks of a one-person CSM mission to lunar orbit, nor the technical problems of running two lunar missions simultaneously.

Perhaps because of these difficulties, NASA chose not to make preparations for astronaut rescue in lunar orbit. This did not stop Bellcomm from considering the problems of lunar orbit survival three years later, in December 1968, shortly after the Apollo 8 CSM became the first piloted spacecraft to return from lunar orbit (see link under "More Information" below).

Source

4-Man Apollo Rescue Mission, AS65-36, M. W. Jack Bell, et al., North American Aviation, November 1965; presentation at NASA Headquarters, 13 December 1965.

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What If Apollo Astronauts Became Marooned in Lunar Orbit? (1968)

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

All alone in the gray: the Apollo 17 Lunar Module Challenger photographed by its crew from a distance of about two miles. Image credit: NASA.

The early piloted Apollo missions were a rapid series of test flights. Apollo 7 (11-22 October 1968), the first manned Apollo, saw a Command and Service Module (CSM) spacecraft and its three-man crew put through their paces in low-Earth orbit. Apollo 8 (21-27 December 1968), originally planned as a test of the CSM and the Lunar Module (LM) in high-Earth orbit, might have been postponed because the LM was not yet ready; instead, Apollo 7's success and the perceived threat to American prestige of a Soviet manned circumlunar mission induced NASA managers to make it a lunar-orbital CSM test and a trial run for the Apollo tracking and communications network.

Apollo 9 tested the CSM, LM, and the Apollo space suit in low-Earth orbit (3-13 March 1969). Apollo 10 (18-26 May 1969) tested the CSM and LM in lunar orbit and rehearsed the Apollo lunar descent procedure down to an altitude of 50,000 feet.

Apollo 11 (16-24 July 1969), the first lunar landing attempt, was also a test flight, though it is seldom seen that way today. In an effort to make that first landing as easy as possible, engineers directed the Apollo 11 LM Eagle to the northern Sea of Tranquility, one of the flattest stretches of lunar equatorial terrain scientists could find. It was, however, also a U.S. victory in the Cold War with the Soviet Union and the first time humans had explored an alien world first-hand. Scientists and engineers fought a running battle over the degree to which scientific exploration should play a role in Apollo 11, and President Richard Nixon telephoned moonwalkers Neil Armstrong and Edwin "Buzz" Aldrin to read a celebratory speech as they stood next to the U.S. flag.

Eagle landed downrange of its planned landing site. Its overworked computer might have flown it into boulder-filled West Crater had it not been for the quick thinking of former X-15 rocket plane test-pilot Armstrong. Apollo 12 (14-24 November 1969) thus became a test of the Apollo system's ability to make a pinpoint landing. The ability to reach a predetermined spot on the moon was important to scientists planning Apollo geologic traverses. It also helped to ensure safety. The Apollo 12 LM Intrepid landed on the Ocean of Storms, another flat plain, just 600 feet from its target, the derelict Surveyor 3 lander, which had preceded it to the site on 20 April 1967.

Any Apollo mission might have failed catastrophically far from Earth, a point driven home by the explosion on board the CSM Odyssey during Apollo 13 (11-17 April 1970). Hollywood scriptwriters notwithstanding, failure was an option during Apollo missions. Apollo pushed the limits of 1960s technology to do extraordinary things.

The Apollo Program had, in fact, claimed lives before the first Apollo spacecraft left Earth: the AS-204 (Apollo 1) fire killed Gus Grissom, Ed White, and Roger Chaffee during a launch pad training exercise on 27 January 1967, barely a month before their planned launch. Because the Apollo 1 fire occurred on the ground, engineers could take apart the AS-204 CSM piece by piece to try to trace the fire's cause. Even so, they never conclusively identified its ignition source.

A December 1964 report by R. Moore of the Project RAND think-tank anticipated that accidents taking place on the moon would be even more difficult to analyze. Moore proposed that NASA continue the Ranger lunar probe series to enable photography of lunar crash sites. The last four Rangers each carried a battery of six television cameras intended to return images to Earth as the spacecraft plummeted toward destructive impact.

If, for example, Eagle had crashed in West Crater, then NASA would have dispatched a Ranger to image the site. Ranger seemed well suited to aiding accident investigators: Ranger 7, which struck the Ocean of Storms on 31 July 1964, had imaged features as small as 18 inches wide in its final seconds before impact.

Ranger 7, 8, and 9 were designed for close-up photography of the lunar surface. Image credit: NASA.

NASA did not act on Moore's proposal, but the concept of Apollo accident site investigations was not forgotten (or, just as likely, it was discovered again). In November 1967, C. Byrne and W. Piotrowski of Bellcomm, NASA's Washington, DC-based Apollo planning contractor, wrote a memorandum in which they looked at whether a Command Module Pilot (CMP) whose moonwalking colleagues had suffered a fatal mishap on the moon might assist investigators by photographing the accident site from the CSM in lunar orbit.

They began by acknowledging that telemetry could provide valuable accident data: they added, however, that "certain types of failure can be imagined which would not permit enough data to be transmitted to support a diagnosis." In those cases, they wrote, observation from lunar orbit might be the only way to collect data that could guide engineers in their efforts to redesign the Apollo system to avoid similar accidents.

Byrne and Piotrowski then looked at the image resolution necessary to make useful observations of an accident site on the moon. To locate and identify an intact LM, which measured a little more than 20 feet tall, images showing details as small as 10 feet across would be needed. Eight-foot resolution would be needed to determine the status of the LM's 12-foot-tall ascent stage; for example, if it had lifted off from the descent stage and then crashed on the surface. Four-foot resolution would suffice to determine whether the LM had tipped over.

The ability to resolve features as small as a yard across would enable engineers to assess landing site roughness and slope. Two-foot resolution would, they estimated, be adequate to discern astronaut bodies on the surface. One-foot resolution would reveal whether the LM landing gear had failed, "hazardous sinkage" had occurred, the LM ascent stage crew cabin lay open to vacuum, or an explosion in the LM had scattered "litter" around the landing site.

Byrne and Piotrowski then took stock of the cameras and telescopes expected to be on board the CSM during a normal lunar mission and their performance if the CSM were orbiting 80 nautical miles (n mi), 40 n mi, or 10 n mi above the accident site. They suggested that CSM propellants budgeted for rescue of astronauts on board an LM ascent stage that attained only a low orbit could be used to lower the CSM's altitude for accident site observations.

The CSM's scanning telescope would, despite its name, not magnify objects, so would be of "no value" as a diagnostic tool, Byrne and Piotrowski judged. The sextant, on the other hand, could magnify objects 28 times. The Bellcomm engineers found that the sextant would offer 8.6-foot resolution at an orbital altitude of 80 n mi, 4.3-foot resolution at 40 n mi, and 1.1-foot resolution at 10 n mi. (Apollo CMPs did in fact use the sextant to spot LMs — or at least the shadows they cast — on the lunar surface.)

The sextant was, however, designed to superimpose a pair of star images, could not be used to photograph objects, and, with a field of view only 1.8° wide, would require a highly skilled operator to spot an LM at all. This would be the case especially at lower altitudes, when the CSM would be moving fastest relative to the surface. Byrne and Piotrowski estimated that an astronaut searching the surface with the sextant at an altitude of 10 n mi would at most have 10 seconds in which to find and observe an accident site.

Apollo 12 Command Module Pilot Richard Gordon trains with cameras and lenses in a Command Module simulator before his November 1969 flight to the moon. Image credit: NASA.

Byrne and Piotrowski wrote that NASA planned to include among the Apollo CSM experiment equipment a Swedish-built Hasselblad 500EL camera with 80-millimeter (mm) f/2.8 and 250-mm f/5.6 lenses. Used with S0-243 film and the 250-mm lens, the Hasselblad 500EL could in theory take photos of the lunar surface with a resolution of 13 feet at 80 n mi of altitude, 6.5 feet at 40 n mi, and 1.6 feet at 10 n mi.

Other constraints would, however, conspire to reduce camera performance. In particular, there was the problem of image motion compensation. Experience gained through Earth photography during the Gemini V mission (21-29 August 1965) showed that astronaut movements were jerky, not smooth, when tracking and photographing targets. Jerky tracking would cause image "smear," reducing resolution.

Byrne and Piotrowski recommended that the CMP mount the Hasselblad 500EL securely in a new-design clamp or bracket at either the CSM hatch window or one of the side windows after he located the LM site. He would then fire the CSM's Reaction Control System thrusters to roll the spacecraft and keep the surface target in his camera's field of view as the CSM passed over it. This form of image motion compensation was unlikely to be perfect; for one thing, roll rate would be affected by factors beyond the CMP's control, such as the distribution and movement of liquid propellants in the CSM's tanks.

As with the sextant, time-over-target would pose a constraint. The Bellcomm engineers assumed that the CMP would need at least 30 seconds to locate the LM on the moon, 15 seconds to prepare the camera and roll the CSM, and 15 seconds for photography.

For a CSM at an altitude of 80 n mi, an LM on the lunar surface would remain in view for two minutes and 24 seconds. This was ample for photography, but at that altitude resolution would be inadequate — no better than 10 feet. At 40 n mi of altitude, the CMP could keep the LM in view for 90 seconds. At 30 n mi, he would have about 60 seconds — the minimum necessary — to find and photograph his target. Byrne and Pietrowski thus selected 40 n mi as the optimum altitude for accident site photography.

The Bellcomm engineers looked at adding a special cartridge of high-contrast film and a 500-mm f/8 lens for the Hasselblad 500EL, and at replacing the Hasselblad 500EL with the Zeiss Contarex Special 35-mm camera and 200-mm f/4 and 300-mm f/4 lenses. These had already reached space on board Gemini V. They noted that both cameras would yield a resolution of about one yard at an altitude of 40 n mi with a secure mounting bracket and adequate image motion compensation. In the end, they favored the Hasselblad 500EL with 500-mm f/8 lens and high-contrast film because it would be about eight pounds lighter than the Zeiss camera.

Byrne and Piotrowski noted that the camera system and techniques they proposed would have uses other than accident site investigation. They might, for example, be used to photograph the landing site after a successful LM landing. This would, among other things, enable scientists to precisely locate the post-deployment position of the Advanced Lunar Scientific Experiment Package, a suite of instruments the moonwalkers would deploy some distance away from the LM. Images of the landing site might also assist geologists in understanding the context of the samples the moonwalking astronauts would return to Earth.

Sources

"A Suggestion for Extension of the NASA Ranger Project in Support of Manned Space Flight," Memorandum RM-4353-NASA, R. C. Moore, The RAND Corporation, December 1964.

"Diagnostic Observation of Lunar Surface Accidents – Case 340," C. Byrne & W. Piotrowski, Bellcomm, Inc., 7 November 1967.

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"Assuming That Everything Goes Perfectly Well in the Apollo Program. . ." (1967)

Humans on Mars in 1995! (1980-1981)

Space: 1995? A stylized schematic of NASA's Integrated Program Plan scenario, proposed in 1969, in the form it might have taken in the 1990s. Image credit: NASA.

NASA's Space Shuttle was conceived in the late 1960s as a fully reusable transport spacecraft for reducing the cost of Earth-orbiting space station logistics resupply and crew rotation. By the time of the first piloted moon landing in July 1969, it came to be seen as an element in an expansive Integrated Program Plan that also included upgraded expendable Saturn V rockets, reusable manned Space Tugs and Nuclear Shuttles, Earth-orbital and lunar-orbital space stations, a lunar surface base, and manned Mars expeditions — all by the mid-1980s. This vision of America's future in space found little favor in either the Executive Branch or Congress, however. By 1972, only the Space Shuttle survived, and then only in a partially reusable form.

For a time, the European Space Research Organization (ESRO) sought to provide NASA with a reusable Space Tug that would reach low-Earth orbit in the Shuttle Orbiter payload bay and travel to orbits that the Shuttle could not reach. In August 1973, however, NASA and ESRO agreed that the latter should develop Spacelab, a system of segmented pressurized modules and unpressurized pallets that would operate in the Orbiter payload bay to provide an interim short-duration space station capability. ESRO joined with the European Launcher Development Organization to form the European Space Agency (ESA) in 1975.

Concept art of Space Shuttle Orbiter with cutaway of European-built Spacelab module in its payload bay. Image credit: NASA.

When the semi-reusable Shuttle first reached space in April 1981, NASA anticipated launching Earth-orbiting satellites and planetary probes beyond the Orbiter's operational altitude using a modest flock of expendable auxiliary rocket stages. The largest and most powerful of these would be the Centaur G-prime, a chemical-propulsion stage with a troubled development history. Centaur G-prime was tapped as NASA's main upper stage for boosting planetary probes — for example, the Galileo Jupiter Orbiter and Probe — onto interplanetary trajectories.

During Shuttle development in the 1970s, NASA budgets were tight, and planning for advanced missions — for example, humans on Mars — ceased within the U.S. civilian space agency. According to some within NASA, talk of Moon bases and piloted Mars missions was tantamount to professional suicide. When planning for NASA piloted Mars missions resumed, it did so first outside of NASA. Mars exploration advocates outside the agency hoped that the Shuttle would inexpensively launch Mars spacecraft components, propellants, and crews, and also serve as a source of hardware that could be modified at modest cost to assemble piloted Mars spacecraft.

Robert Parkinson, an engineer with the Propellants, Explosives, and Rocket Motor Establishment in Great Britain, was among the first individuals to write about a NASA piloted Mars mission based on Shuttle and Shuttle-related hardware. Inspired by the writings of Arthur C. Clarke and Wernher von Braun, Parkinson had joined the British Interplanetary Society in 1956. In a series of papers spanning 1980-1981, he wrote of a capable chemical-propulsion NASA Mars expedition plan which he dubbed "Mars in 1995!"

Parkinson inventoried Shuttle-derived and Shuttle-related hardware which he believed would become available by 1990 as part of NASA's planned Earth-orbital operations. Development of such systems, he opined, "probably only awaits freeing of funding currently tied up in [development of] the Shuttle."

His long list of useful hardware included, in addition to the Space Shuttle, three systems designed mainly for rocket propulsion: a powerful Heavy Lift Vehicle (HLV) capable of launching into low-Earth orbit payloads larger than the Shuttle Orbiter's payload bay could accommodate; a Heavy Boost Stage (HBS) roughly the size of the S-IVB stage NASA used in the late 1960s/early 1970s to launch Apollo spacecraft out of Earth orbit toward the moon; and a drum-shaped high-performance Orbital Transfer Vehicle (OTV) with an optional crew cabin.

Parkinson's inventory also included important systems not related to propulsion: an extendable solar array for generating up to 25 kilowatts of electricity; Spacelab modules capable of operating in free-flyer mode (that is, outside of a Space Shuttle payload bay); closed-cycle Space Station life-support systems; and androgynous docking units resembling those which linked together Soviet and American spacecraft during the July 1975 Apollo-Soyuz Test Project mission.

Because such systems would be developed for Earth-orbital operations regardless of whether NASA planned a Mars expedition, a Mars expedition which employed them could be carried out in the 1990s with essentially no development cost. The piloted Mars lander would be the only wholly new piloted spacecraft developed for the Mars expedition.

Parkinson placed the cost of his expedition at just $3.3 billion in his first "Mars in 1995!" paper, of which developing and testing the Mars lander would account for about $740 million. He raised the total cost to $4.844 billion in a subsequent paper, of which $2.359 billion would be spent on the lander. Even this higher cost figure was, he noted, only five times the cost of the twin robotic Viking missions which landed on and orbited Mars in 1976. He added that "given the right circumstances, it is actually cheaper to send men [to Mars] than to try to do the same thing with dozens of robot expeditions."

Parkinson's 1995 NASA Mars expedition would begin with eight Space Shuttle launches in September-October 1994. Reflecting early Shuttle-era optimism, Parkinson estimated that each of the eight weekly Shuttle launches would cost just $28.75 million. Assembly of the expedition's three Orbital Assembly (OA) spacecraft — in reality, a single spacecraft system launched from Earth orbit in three parts — would take place in a 400-kilometer-high circular Earth orbit. The eighth Shuttle Orbiter would deliver the five Mars astronauts and stand by to observe the beginning of their departure from Earth orbit. In the event of trouble before the beginning of Earth-orbit departure, the Shuttle could recover the Mars astronauts and return them to Earth.

The view from Orbital Assembly 1: A rear-facing porthole displays the setting Sun and OA 2 and OA 3 during departure from Earth-orbit. OA 2 is the nearer of the two. From fore to aft, it comprises the docking module with stowed twin rectangular solar arrays; a Spacelab-derived crew module; an unpressurized pallet with extended medium-gain dish antennas; a Mars-orbit departure/Earth-orbit capture OTV; a Mars-orbit capture OTV; and a Heavy Boost Stage. OA3 from fore to aft comprises the Lander Module; a stores module; an OTV with a crew cabin; and a Heavy Boost Stage. Image credit: © David A. Hardy/http://www.astroart.org

Two OAs, which Parkinson also designated "Orbiters," would at launch from Earth orbit each comprise an HBS, a pair of 30-ton OTVs (one for Mars orbit capture and one for Mars orbit departure/Earth-orbit capture), and a Spacelab-derived pressurized module with an aft-mounted unpressurized pallet and a forward-mounted androgynous docking unit. The Spacelab-derived modules would provide living and working space for the crew, as well as protection from the six solar flares Parkinson said the crew could expect during their 18-month Mars expedition.

Orbiter 1, with a crew of three and a mass at launch from Earth orbit of 211.3 metric tons, would have stowed on its unpressurized pallet a deployable six-meter-diameter high-gain dish antenna for high-data-rate radio communication with Earth and two 2.5-meter-diameter Venus atmosphere entry probes. Orbiter 2, with a mass of 210.9 metric tons and a crew of two, would include attached to its forward-mounted androgynous unit a 1750-kilogram cylindrical docking module with three unoccupied androgynous docking ports and two extendable solar arrays. Either Orbiter could support the entire crew in an emergency.

OA 3, the unmanned Lander Assembly (LA), would have at launch from Earth orbit a mass of only 193.5 metric tons. In addition to an HBS, it would comprise an OTV; a three-meter-diameter drum-shaped OTV crew cabin with an androgynous docking unit; a drum-shaped stores module; and the 7.6-meter-diameter, 15.98-metric-ton Lander Module, which would transport three astronauts from Mars orbit to a preselected landing site on the martian surface. The stores module would partially cover the Lander Module to shield it from meteoroids.

Parkinson's stores module had a central tunnel running from its aft-mounted androgynous docking unit — linked to the OTV/crew cabin — to its forward-mounted androgynous docking unit. The forward unit would link to the Lander Module's lightweight "skeleton" androgynous unit. The module would carry supplies for the expedition's Mars-bound leg; three 1225-kilogram automated Mars sample-returner landers; a 938-kilogram propulsion package that would enable one Mars sample-returner to change its orbital plane from near-equatorial to near-polar and back so that it could reach and return a sample from one of the martian polar ice caps; six 31-kilogram penetrator hard-landers; and a 473-kilogram Mars-orbiting radio-relay satellite to enable Mission Control on Earth to remain in continuous contact with the crew on the surface of Mars.

On 8 November 1994, the three OAs would ignite their HBS engines to begin Earth-orbit departure. Over the course of several revolutions about the Earth, they would fire the HBS rocket motors at their perigee (Earth-orbit low point) to raise their apogee (Earth-orbit high point). A maneuver at final apogee would tweak the plane of the expedition's Sun-centered Mars-intersecting orbit, then a final perigee burn would push the three OAs out of Earth's gravitational grip.

After escape from Earth, the OAs would cast off their spent HBSs and dock to form the Earth-to-Mars cruise configuration. The crew would first dock Orbiter 1 and Orbiter 2 nose-to-nose with the docking module between them. The LA OTV/crew cabin would undock from the stores module/Lander Module, then the former would dock at one of the docking module's lateral (side) ports. The stores module/Lander Module would dock automatically at the other lateral port, opposite the LA OTV/crew cabin. The crew would then extend the twin solar arrays mounted on the docking module. After they finished assembling their spacecraft, the five astronauts would have available 1125 cubic meters of living space.

The OAs would reach Mars on 10 June 1995. Shortly before arrival, the crew would retract the solar arrays to protect them from deceleration stress during the Mars capture maneuver. Orbiter 1 would undock from the docking module on Orbiter 2, and the LA OTV/crew cabin and stores module/Lander Module would both undock from the docking module lateral ports and redock with each other.

The two Orbiters would then ignite their Mars orbit capture OTV engines to slow down so that martian gravity could capture them into a 23,678-by-3748-kilometer Mars-centered orbit with a period of 13.5 hours. The single LA OTV would perform an identical maneuver. Parkinson proposed the high elliptical orbit as a propellant-saving measure; relatively loosely bound to Mars, it would enable an economical Mars escape when time came to begin the return to Earth.

Parkinson's "Mars in 1995!" spacecraft in Mars orbit. Spacelab-derived crew modules are labeled "NASA" and "esa." Numerals on the twin Mars orbit departure/Earth-orbit capture OTVs identify the Orbiters of which they are part. The Lander Module is at upper right, docked with the stores module, which is in turn docked with the Orbiter 2 docking module. Extended solar arrays place the LA OTV/crew cabin (labeled "3") in shadow. The painting shows a deorbit rocket pack strapped to the Lander Module heat shield; Parkinson also proposed using the Lander Module Reaction Control System thrusters for the deorbit maneuver ahead of landing on Mars. Image credit: © David A. Hardy/http://www.astroart.org

The two Orbiters would cast off their spent Mars orbit capture OTVs and redock to form their Mars orbital configuration. The Lander Assembly would split as before so that its components could resume their places at the docking module lateral ports. Because the Lander Assembly would be less massive than the two Orbiters, its OTV would retain about 7000 kilograms of nitrogen tetroxide/hydrazine propellants after its Mars orbit capture burn and would not be cast off.

After they surveyed prospective landing sites from orbit at periapsis (orbit low-point) over several days, the astronauts would ready the Lander Module for descent to Mars's surface. Three astronauts would strap into couches in its cramped ascent module capsule and undock from the stores module. At apoapsis (orbit high-point), they would fire the Lander Module's Reaction Control System thrusters to lower its periapsis to 50 kilometers, where Mars atmosphere entry would begin. A bowl-shaped heat shield modeled on the Viking lander aeroshell design would protect the Lander Module during its fiery descent through the thin martian atmosphere.

The Lander Module would slow to Mach 2.5 by the time it fell to an altitude of 10 kilometers, then a 20-meter-diameter ballute ("balloon-parachute") would deploy to slow it to subsonic speed. Five kilometers above Mars, the ballute would separate and a parachute would deploy. At the same time, the Lander Module heat shield would fall away, exposing its four landing engine clusters and three landing legs. A downward-pointing camera would enable the Lander Module pilot to observe the planned landing site for the first time since leaving Mars orbit. The landing engines would ignite 800 meters above Mars; then, moments later, the parachute would separate. The pilot would then guide his craft to a safe landing.

Parkinson's Lander Module design, which resembled conical lander designs put forward beginning in the mid-1960s, included in its lower section a two-by-three-meter crew cabin. Soon after landing, the crew would climb down through a tunnel into the cabin and don Mars surface suits. After depressurizing the crew cabin, they would open a door-like hatch, walk down a short ramp, and put the first human boot prints on another planet.

At the Mars landing site. Image credit: © David A. Hardy/http://www.astroart.org

Parkinson called for a 20-day Mars surface stay, during which the three astronauts would explore using 500 kilograms of science equipment and a 500-kilogram unpressurized electric-powered rover more capable than the Lunar Roving Vehicle used during the Apollo 15, 16, and 17 missions. As they explored, they would collect up to 350 kilograms of Mars rock and dirt samples for return to laboratories on Earth.

The two astronauts on board the docked OAs, meanwhile, would deploy the mission's cargo of automated Mars probes. The 2.5-meter-diameter automated sample-returners would each collect and launch up to a kilogram of rock and soil (ice, in the case of the polar sample-returner) into a 350-kilometer circular Mars orbit.

When the time came to leave Mars's surface, the three astronauts would resume their places in the Lander Module ascent capsule and ignite three engines similar to the Apollo Lunar Module ascent-stage engine. The ascent capsule would blast free of the Lander Module's lower section, leaving behind the crew cabin. During the first-stage burn, four strap-on propellant tanks would feed the three engines. After first-stage shutdown, the tanks and two outer engines would detach; then, after a brief coast, the remaining engine would reignite to place the ascent capsule into a 350-kilometer circular Mars orbit.

As the docked OAs neared apoapsis, one astronaut would board the Lander Assembly OTV/crew cabin and undock from the docking module, then would ignite the OTV's rocket engine to descend to a rendezvous with the Lander Module ascent capsule. The OTV/crew cabin would link up with the ascent capsule, then the surface crew would transfer with their Mars samples.

After the Lander Module ascent capsule was cast off, the OTV/crew cabin would rendezvous with and recover the three orbiting sample-returner sample capsules. The OTV/crew cabin pilot would then fire its engine at periapsis to raise its apoapsis so that it could return to the docked OAs. Parkinson calculated that, even after this series of maneuvers, the OTV/crew cabin would retain enough propellants for two astronauts to carry out a 10-day sortie to Phobos, the  innermost and largest martian moon.

On 25 July 1995, the expedition would depart Mars orbit. Before departure, the astronauts would cast off the OTV/crew cabin and depleted stores module, retract the twin solar arrays, and undock Orbiter 1 from Orbiter 2. Each would then ignite its remaining OTV engine at periapsis to escape Mars orbit and begin a five-month journey to Venus. After OTV shutdown, the crew would redock the two Orbiters and extend the solar arrays. With the stores module gone, the astronauts would rely on supplies packed along the walls of the Spacelab-derived crew modules; these would have served as radiation shielding during the Mars-bound voyage and in Mars orbit.

The Venus detour, Parkinson explained, would accelerate the spacecraft toward Earth. Without the gravity-assist from Venus, the round-trip Mars voyage would need three years; with it, the Mars expedition could be completed in half that time. During the Venus swingby, the crew would deploy the twin Venus probes mounted on Orbiter 1's unpressurized pallet. The probes would be modeled on the Large Probe from the 1978 Pioneer Venus Multiprobe mission.

NASA's first Mars expedition would return to Earth 10 months after departing Mars, on 16 May 1996. The astronauts would again undock the Orbiters and retract the twin solar arrays on the Orbiter 2 docking module. They would ignite the OTV engines for the final time to capture into a 77,687-by-6800-kilometer Earth orbit with a period of 24 hours, then would redock and extend the solar arrays.

A Space Shuttle Orbiter, meanwhile, would transport into low-Earth orbit an OTV/crew cabin, which would climb to a rendezvous with the waiting Mars spacecraft and dock with the docking module. The Mars crew would board with their samples, then the OTV/crew cabin pilot would undock and fire his craft's motor to return to the waiting Shuttle Orbiter. The abandoned docked OAs would remain in Earth orbit as a long-lived monument to the early days of U.S. piloted Solar System exploration. The Shuttle Orbiter would deorbit to deliver the Mars astronauts, physically weakened by 18 months in weightlessness, to a hero's welcome on Earth.

NASA human spaceflight would follow a path very different from any Parkinson and other optimistic early 1980s space planners anticipated, though until early 1986 they could be forgiven for holding onto their dreams. In July 1982, President Ronald Reagan declared the Space Shuttle operational. The first Spacelab flight, STS-9/Spacelab 1 in late 1983, saw an ESA astronaut join American astronauts in Earth orbit for the first time. In his January 1984 State of the Union address, Reagan called for a Space Station and invited European, Canadian, and Japanese participation. The Shuttle-launched station was to be completed by 1994.

Reagan's station was meant to serve as a relatively low-cost laboratory. Such an orbital facility would have no need of the heavy-lift rockets, large in-space stages, and OTVs Parkinson had assumed would become available by 1990. NASA hoped that the lab station might be designed as a foot in the door leading eventually to a more ambitious and costly "shipyard" station, but the January 1986 Challenger accident meant that such schemes came under close scrutiny and were found wanting. At the same time, systems such as the Centaur G-prime stage were judged to be too volatile to carry on board a piloted spacecraft.

The cost of Shuttle operations was also a major factor in the death of optimistic early 1980s space plans. The Nixon Administration had made decisions that ensured low Shuttle development cost and high operations cost. NASA, a part of the Executive Branch, felt obligated despite this to continue to tout Shuttle economy.

The U.S. space agency was, however, cagey about how much it actually spent on Shuttle missions. For a time, a figure of $110 million per flight was used in Shuttle payload cost calculations. Independent cost estimates placed the per-flight cost of the Shuttle as high as $1.5 billion; even assuming that the true cost was "only" $1 billion per flight, the Earth-to-orbit transportation cost of Parkinson's Mars expedition would have reached $9 billion, or about double his highest cost estimate for his entire expedition.

The third, fourth, and fifth images of this post are © David A. Hardy/http://www.astroart.org. Used by kind permission of the artist.

Sources

"Is Nuclear Propulsion Necessary? (or Mars in 1995!)," AIAA-80-1234, R. Parkinson; paper presented at the AIAA/SAE/ASME 16th Joint Propulsion Conference in Hartford, Connecticut, 30 June-2 July 1980.

"Mars in 1995!" R. Parkinson, Analog Science Fiction/Science Fact, June 1981, pp. 38-49.

"A Manned Mars Mission for 1995," R. Parkinson, Journal of the British Interplanetary Society, October 1981, pp. 411-424.

"Mars in 1995!" R. Parkinson, Spaceflight, November 1981, pp. 307-312.

More Information

Evolution vs. Revolution: The 1970s Battle for NASA's Future

Gumdrops on Mars (1966)

Dyna-Soar's Martian Cousin (1960)

Astronaut Sally Ride's Mission to Mars (1987)

Astronaut Dr. Sally Ride on board the Space Shuttle Orbiter Challenger during STS-7 (June 1983), her first flight into space. Image credit: NASA.

Dr. Sally Ride was a member of the 1978 astronaut class, the first selected for Space Shuttle flights. During mission STS-7 (18-24 June 1983), she became the first American woman in space. Ride flew one more Shuttle mission — STS-41G (5-13 October 1984) — and served on the Rogers Commission investigating the 28 January 1986 Shuttle Challenger accident before James Fletcher, in his second stint as NASA Administrator, made her his Special Assistant for Strategic Planning on 18 August 1986.

Fletcher charged Ride with drafting a new blueprint for NASA's future. She had help from a small staff, a 12-member advisory panel led by Apollo 11 astronaut Michael Collins, and a six-member space mission design team at Science Applications International Corporation (SAIC) in Schaumburg, Illinois. The result of her 11-month study was a slim report called Leadership and America's Future in Space.

On 22 July 1987, Ride testified before the U.S. House of Representatives Subcommittee on Space Science and Applications about her report. She told the Subcommittee that the "civilian space program faces a dilemma, aspiring toward the visions of the National Commission on Space, but faced with the realities of the Rogers Commission Report." The National Commission on Space (NCOS), mandated by Congress and launched by President Ronald Reagan on 29 March 1985, had been meant to blueprint NASA's future until about 2005. The NCOS counted among its members such luminaries as Neil Armstrong, Chuck Yeager, Gerard O'Neill, Kathryn Sullivan, physicist Luis Alvarez, planetary scientist Laurel Wilkening, and former U.S. Ambassador to the UN Jeane Kirkpatrick.

Headed by Thomas Paine, NASA Administrator from 1968 to 1970, the NCOS had exceeded its mandate. Its report, titled Pioneering the Space Frontier, was a wide-ranging 50-year master plan for "free societies on new worlds" that would have been dismissed as unrealistic even had it not been unveiled in the chaotic aftermath of Challenger. By some accounts, Paine dominated the NCOS process to such an extent that some of its less patient members — for example, Chuck Yeager — ceased to attend meetings.

The Ride Report. Image credit: NASA.

Ride's study aimed to produce a more realistic blueprint of NASA's future. Whereas the NCOS report urged immediate adoption of its expansive (and expensive) "vision," Ride outlined four much more limited "Leadership Initiatives." They were, she explained, meant to serve "as a basis for discussion." They included a piloted Mars program; "Mission to Planet Earth," which aimed to study Earth from space using satellites; "Mission from Planet Earth" (exploration of the Solar System using robotic spacecraft); and construction and operation of a permanent outpost on the Moon.

Each of Ride's proposals could occur in isolation; none necessarily depended on or followed from the others. By Fletcher's command all would rely to some degree on NASA's planned low-Earth orbit (LEO) Space Station.

SAIC began design of the Ride Report's piloted Mars program in January 1987. The company presented its final report to the Office of Exploration (nicknamed "Code Z" for its NASA Headquarters mail code) in November of that year. James Fletcher created Code Z in June 1987 and placed Ride in charge as his Acting Assistant Administrator for Exploration. By then, Ride had announced that she would leave NASA in August. John Aaron, who replaced her as Code Z chief, made SAIC's report the basis for piloted Mars and Phobos mission "Case Studies" in Fiscal Year 1988.

SAIC employed a split/sprint Mars mission design. The company credited a 1985 joint University of Texas/Texas A & M student design project with originating the split/sprint concept, though similar concepts can be traced back to the 1950s. The split/sprint mission would use a pair of spacecraft: an automated one-way cargo spacecraft "slowboat" launched first followed by a piloted "sprint" spacecraft. Both would burn chemical propellants and employ aerobraking.

The cargo spacecraft would follow a propellant-saving low-energy path to Mars. It would transport to Mars orbit propellants for the piloted spacecraft's return to Earth. The piloted sprint spacecraft would leave LEO only after the cargo spacecraft had arrived safely in Mars orbit.

So that its six-person crew would be exposed to weightlessness, radiation, and isolation for as short a time as possible, the piloted spacecraft would follow a roughly six-month path to Mars, remain at the planet for only one month, and then return to Earth in about six months. This would yield a piloted Mars mission duration of no more than 14 months.

Shuttle-derived heavy-lift launch vehicle. Image credit: M. Dowman/Eagle Engineering.

In common with most other post-Challenger piloted Mars plans, the SAIC team abandoned the Space Shuttle as its primary means of launching spacecraft components and propellants to LEO. In the Shuttle's place, it proposed a heavy-lift rocket based in part on Shuttle hardware. The new rocket would debut in 1996 with a launch capability of 36 metric tons to LEO, then would evolve by 2002 to carry 91 metric tons to LEO.

Though it featured a piloted mission of short duration — which in most cases would imply large propellant expenditure — the SAIC split/sprint mission design provided substantial propellant savings by refueling the crew spacecraft in Mars orbit. This would in turn slash the number of costly heavy-lift rockets required to launch spacecraft components and propellants to the Space Station for assembly.

Launching a single round-trip combined crew/cargo sprint spacecraft would, SAIC calculated, need 25 heavy-lift rockets, while the two-spacecraft split/sprint design would need only 15. In addition, because the cargo and crew spacecraft would depart Earth more than a year apart, heavy-lift launches could be spread out over a longer period, making launch vehicle, payload, and launch pad preparations less sensitive to delays caused by weather or rocket malfunctions.

By the time the heavy-lifter attained its maximum launch capability in 2002, Phase I of SAIC's three-phase Mars program would be ended and Phase II would just have begun. Phase I, starting in 1992, would comprise a series of robotic precursor missions. Mars Observer, in 1987 already an approved NASA mission, would map Mars from orbit beginning in 1993; then, in 1995, Mars Observer 2 would establish and act as radio relay for a planet-wide network of hard-landed penetrator sensor stations. Orbital mapping and the seismic/meteorological net would help scientists and engineers to select landing sites for automated Mars Sample Return (MSR) and piloted Mars missions.

Mars Rover Sample Return concept. Image credit: NASA.

A pair of MSR spacecraft would depart Earth in 1996 to collect Mars surface samples and return them to high-Earth orbit (HEO) in 1999. A reusable Orbital Maneuvering Vehicle (OMV) based at the LEO Space Station would retrieve the samples from HEO and deliver them for quarantine and initial study to an "isolation half-module" added to the Station in 1998. The samples would enable scientists to identify hazards in Mars surface materials and would aid engineers in the design of spacecraft, rovers, habitats, space suits, and tools.

Phase I would also include biomedical research on board the Space Station, which Ride assumed would reach Permanent Manned Configuration (PMC) in 1994. Almost immediately after it achieved PMC, NASA would add a Life Science Module. A six-person crew would then conduct a Mars mission simulation on board the Station that would last for the planned piloted sprint mission duration of 14 months.

If the astronauts remained healthy after the simulation, which would be conducted in weightlessness, then in 1996 NASA would begin development of a Mars sprint spacecraft lacking any provision for artificial gravity (that is, no part of it would rotate to create acceleration which the crew would feel as gravity). A module for housing Mars spacecraft assembly crews would join the Station in 2002, kicking off Phase II of SAIC's Mars program. The cargo spacecraft for the first split/sprint mission would depart LEO during the favorable 2003 low-energy Earth-Mars transfer opportunity.

If, on the other hand, biomedical researchers determined that the simulation crew had suffered harm from their long stay in weightlessness, then NASA would add a "variable-gravity module" to the Station in 2001. Crews would conduct simulations in the spinning module to determine the minimum level of artificial gravity required to safeguard astronaut health. Development of an artificial-gravity sprint spacecraft would not commence until after the simulations ended in 2004. If the artificial-gravity sprint spacecraft needed as much development time as its no-gravity counterpart, then the first piloted Mars mission might not leave Earth until 2013. SAIC largely ignored this possibility.

SAIC's automated cargo spacecraft (right) in Earth-orbit launch configuration with large Orbital Transfer Vehicle (OTV). The conical vehicle at the center of the cargo spacecraft's dish-shaped aeroshell is the piloted Mars Lander. Spherical tanks around the Mars Lander contain Earth-return propellants for the piloted sprint spacecraft. Image credit: Science Applications International Corporation.

Launching parts and propellants from Earth's surface for the 238.5-metric-ton cargo spacecraft and a single 349.6-metric-ton reusable Orbital Transfer Vehicle (OTV) would require seven heavy-lift rocket launches. The cargo spacecraft would carry at the center of its 28-meter-diameter bowl-shaped Mars Orbit Insertion (MOI) aerobrake heat shield the mission's two-stage, 60-metric-ton Mars Lander.

Spherical tanks surrounding the Lander would hold the 82.5 tons of cryogenic liquid hydrogen/liquid oxygen propellants the piloted sprint spacecraft would need for return to Earth. The cargo spacecraft would also carry 4.2 metric tons of propellants for correcting its course during flight from Earth to Mars and 16.4 metric tons of propellants for circularizing its Mars-centered orbit after it aerobraked in the martian atmosphere. A 9.1-metric-ton refrigeration system would prevent the propellants from boiling and escaping.

On 9 June 2003, the 30.5-meter-long cargo spacecraft/OTV stack would move away from the Space Station using small thrusters. The OTV would then ignite its main engines to push the cargo spacecraft out of LEO. After sending the cargo spacecraft on its way, the OTV would separate, turn end over end, fire its engines to slow itself, aerobrake in Earth's upper atmosphere, fire its engines to circularize its orbit, and return to the Station for refurbishment, refueling, and reuse.

The cargo spacecraft's course would intersect Mars on 29 December 2003. It would aerobrake in the upper atmosphere of Mars to slow itself so that the planet's gravity could capture it into orbit. The cargo spacecraft would rise to its orbital apoapsis (high point), then fire its rocket engines to raise its orbit periapsis (low point) out of the martian atmosphere and circularize its orbit. Flight controllers would then begin careful checkout and monitoring of the cargo spacecraft and its cargo, paying special attention to the propellants the piloted sprint spacecraft would need for return to Earth.

Partial cutaway view of SAIC's piloted sprint Mars spacecraft. A = bowl-shaped Mars Orbit Insertion aerobrake heat shield; B = cylindrical habitat modules (2); C = cylindrical logistics module; D = cylindrical "bridge" tunnel; E = cylindrical tunnel linking docking unit (right), bridge tunnel, and Earth Recovery Vehicle; F = drum-shaped Earth Recovery Vehicle; G = flattened conical aerobrake heat shield; H = engines (2); I = spherical liquid hydrogen tank; J = spherical liquid oxygen tanks (2). Not shown: cylindrical command module, cylindrical airlock module, and one spherical liquid hydrogen tank. Image credit: Science Applications International Corporation/DSFPortree.

SAIC offered a piloted spacecraft design with 4.4-meter-diameter Station-derived pressurized crew modules connected in a "race track" configuration; that is, in a square with each module linked by short tunnels at or near their ends. A pair of 12.2-meter-long habitat modules, each with a mass of 15.5 metric tons, would form two sides of the square; a 12.2-meter-long, 10.8-metric-ton logistics module would form the third side; and an 8.5-metric-ton command module and a 3.2-metric-ton airlock module would together make up the fourth.

A pressurized "bridge" tunnel would cross the inside of the square, linking directly the two habitat modules. Another tunnel would pierce the center of the bridge tunnel vertically. Its forward end would link with the top of the drum-shaped, 11.9-metric-ton Earth Recovery Vehicle (ERV), while its aft end would carry a docking unit. The ERV, situated deep within the spacecraft's structure, would double as the crew's solar flare "storm shelter."

Four spherical tanks holding a total of 91.9 metric tons of cryogenic liquid hydrogen/liquid oxygen propellants and two rocket engines with a combined mass of 4.6 metric tons would be mounted atop the crew modules. The vertical tunnel's docking unit would protrude beyond the sprint spacecraft's twin engine bells.

The ERV/storm shelter would be mounted at the center of a one-metric-ton, 11.4-meter-diameter flattened conical aerobrake heat shield. ERV, ERV aerobrake, crew modules, tunnels, propellant tanks, and engines would nest within a bowl-shaped, 25-meter-diameter, 16.1-metric-ton MOI aerobrake. Except during propulsive maneuvers and aerobraking, four solar arrays capable of generating a total of 35 kilowatts of electricity at the piloted spacecraft's maximum distance from the Sun (that is, in Mars orbit) would extend beyond the edge of the MOI aerobrake. During maneuvers and aerobraking, the arrays would be folded out of harm's way atop the crew modules. Fully assembled and loaded with propellants, the piloted spacecraft's mass would total 193.7 metric tons.

An assembly crew at the Space Station would link a newly assembled small (197.4-metric-ton) OTV to the piloted spacecraft, then would attach the larger OTV used to launch the cargo spacecraft to the new OTV. This would create a 48-meter-long, 738.7-metric-ton Earth-departure stack.

SAIC's piloted sprint spacecraft (right) in Earth-orbit launch configuration with large and small reusable OTVs. Image credit: Science Applications International Corporation.

The stack would move away from the Space Station on 21 November 2004. Shortly thereafter, the first OTV would ignite its engines to start the second OTV and the piloted sprint spacecraft on their way. Its work completed, it would then separate, aerobrake in Earth's atmosphere, and return to the Station for reuse. The second OTV would repeat this performance, then the piloted sprint spacecraft would burn nearly all of its propellants to place itself on course for Mars.

The piloted spacecraft would aerobrake in the martian atmosphere and fire its engines to circularize its orbit on 3 June 2005. Almost immediately after MOI, the crew would rendezvous with the waiting cargo spacecraft. Three astronauts would board the Mars Lander, deorbit, and land at the pre-selected landing site. They would explore the site for between 10 and 20 days.

The other three astronauts, meanwhile, would transfer the Earth-return propellants stored on board the cargo spacecraft to the piloted spacecraft's empty tanks. They would also discard the piloted spacecraft's MOI aerobrake.

SAIC noted that the ideal trajectory for a sprint Mars mission launched as soon as possible after the cargo spacecraft arrived at Mars on 29 December 2003, would have the piloted spacecraft depart Earth on 8 January 2005, reach Mars on 2 August 2005, depart Mars on 1 September 2005, and return to Earth on 8 January 2006. SAIC's Earth-departure date, a little more than a month ahead of the ideal date, would increase piloted mission duration by almost two months (that is, to 14 months).

Launching the piloted sprint spacecraft early would, however, add an abort option to the mission. For example, if the sprint spacecraft were en route to Mars and the cargo spacecraft propellant refrigeration system failed, allowing the sprint spacecraft Earth-return propellants it kept liquid to turn to gas and escape, then the crew could use the propellants they would have used to circularize their orbit around Mars after aerobraking to cause their spacecraft to skim through Mars's uppermost atmosphere on 3 July 2005. This aero-maneuver, if properly executed, would nudge the piloted spacecraft's course enough that it would intersect Earth on 15 January 2006.

SAIC's Mars crew lander would reach Mars orbit 18 months ahead of its three-person crew. It would become the surface crew's base of operations during a Mars surface stay lasting up to 20 days. Image credit: P. Hudson/NASA.

SAIC envisioned that NASA would launch a series of three split/sprint missions by the end of the first decade of the 21st century. While the first crew explored the surface of Mars and worked in orbit to prepare their spacecraft for the trip home, the cargo spacecraft for the second Mars crew would depart LEO boosted by the same large aerobraking OTV the first mission's cargo and piloted spacecraft had used. The second crew would leave Earth orbit in early 2007 and return from Mars in early 2008. The final crew in the series would depart for Mars in early 2009 and return home in early 2010.

After the third Mars expedition, establishment of a Mars base — Phase III of SAIC's program — could begin. The company provided few details of Phase III.

With their surface mission completed, the first Mars explorers would lift off in the Mars Lander ascent stage. SAIC calculated that the ascent stage would make up about half the mass of the Lander. The piloted spacecraft would rendezvous and dock with the ascent stage in Mars orbit to collect the surface crew and their samples of Mars rocks, sand, and dust. On 2 August 2006, shortly after casting off the spent ascent stage, the astronauts would fire the piloted spacecraft's twin engines to begin their five-month return to Earth.

As Earth loomed large ahead of what remained of the sprint spacecraft, the astronauts would enter the ERV capsule with their samples. The ERV, which would resemble the early "hat box" design of NASA's planned Space Station lifeboat, would slide out of a radiation shield housing that would remain behind on the crew spacecraft. The abandoned sprint spacecraft would then fire its engines a final time to miss Earth and enter orbit about the Sun.

SAIC based its ERV configuration on this NASA design for a Space Station lifeboat. Image credit: NASA.

The ERV would aerobrake in Earth's atmosphere, then an automated OMV from the Space Station would retrieve it. After physical examinations and a period of quarantine on board the Station, the first Mars crew would return to Earth on board a Space Shuttle.

SAIC wrote that its piloted split/sprint Mars mission could support international space cooperation. Other countries, both allies and rivals, could contribute money, services such as propellant delivery, crew members, robotic precursor missions, spacecraft components, and even entire spacecraft. For all the countries involved, piloted Mars missions would "provide an effective catalyst for significant advances in automation, robotics, life sciences[,] and space technologies. . .[and], through direct experience, address and answer key questions about long-duration human space flight and the role of human beings in space exploration."

NASA did not much care for the Ride Report; in fact, the agency at first refused to publish it. Ultimately NASA printed about 2000 copies — an unusually small number for such a high-level report. Perhaps this was because Ride acknowledged that NASA could not hope to lead in all areas of space endeavor. In addition, Ride proposed a manned Mars program after the Space Station was built with no intervening manned Moon program, placed robotic programs on a par with their piloted counterparts, and implied that NASA might not need a new piloted space initiative after it finished building the Space Station.

Her matter-of-fact tone seems also to have annoyed some within NASA. Ride was nearing the end of her nine-year NASA career, so felt free to express herself. She was quick to point out when NASA's actions apparently belied its enthusiasm for piloted missions beyond LEO; for example, when she noted the uncomfortable fact that NASA boss Fletcher had committed only 0.03% of the agency's budget to funding the new Office of Exploration. This, Ride noted, gave the appearance that Code Z had been established merely to quell critics who complained that NASA had no long-term goals.

Following her departure from NASA, Ride worked briefly at Stanford University, her alma mater. In 1989, she became a physics professor at the University of California, San Diego. She led space public outreach projects for NASA, co-founded the Sally Ride Science education company in 2001, participated in the Columbia Accident Investigation Board in 2003, and co-authored several science books for children. In early 2011, she was diagnosed with pancreatic cancer. She died at age 61 on 23 July 2012.

Sources

"Piloted Sprint Missions to Mars," AAS 87-202, J. Niehoff and S. Hoffman, The Case for Mars III: Strategies for Exploration - General Interest and Overview, Carol Stoker, editor, 1989, pp. 309-324; paper presented at the Case for Mars III conference in Boulder, Colorado, 18-22 July 1987.

Leadership and America's Future in Space, Sally K. Ride, NASA, August 1987.

Piloted Sprint Missions to Mars, Report No. SAIC-87/1908, Study No. 1-120-449-M26, Science Applications International Corporation, November 1987.

Humans to Mars: Fifty Years of Mission Planning, 1950-2000, David S. F. Portree, Monographs in Aerospace History #21, NASA SP-2001-4521, NASA History Division, February 2001.

More Information

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Gumdrops on Mars (1966)

The Collins Task Force Says Aim for Mars (1987)

The Apollo 11 crew of Neil Armstrong (left), Michael Collins, and Edwin Aldrin. Image credit: NASA.

The January 1986 Challenger Space Shuttle accident laid bare many shortcomings of the U.S. space program. NASA, which only 14 years before had soared to the Moon, had suffered chronic underfunding since the truncated Administration of President Richard Nixon (1969-1974). At the same time, expectations for the Shuttle grew, until, in January 1984, President Ronald Reagan called upon NASA to use its Shuttle fleet to build an Earth-orbiting Space Station within a decade.

NASA had eagerly encouraged such expectations. The Shuttle, it promised, would fly cheaply and often, permitting it to replace all U.S. expendable rockets and fly commercial payloads for domestic and foreign customers. It would fly so inexpensively that Shuttle astronauts would economically service Earth-orbiting satellites. The Shuttle would reliably launch all U.S. robotic planetary missions, saving so much money that a new era of planetary exploration could begin. By conducting secret military missions — many launched from California into near-polar orbits — it would help to ensure U.S. national security. It would be safe enough that it would carry non-astronaut passengers — researchers, teachers, journalists, and others — and its crews would fly without pressure suits.

The Space Shuttle would also open the door to new space programs. The Space Station, NASA declared, was "the next logical step" after the Shuttle. That implied other, unspecified steps after the Space Station, in the 1990s and beyond.

Even before the Challenger accident called many of NASA's promises into question, Reagan had come under pressure to give the space agency a long-term goal that would provide a clear rationale and context for the Shuttle and Station programs. In late 1984, in fact, Congress mandated that the White House appoint an independent commission to study NASA's long-term options and offer recommendations for its future direction.

The Space Shuttle was developed in a dangerously constrained funding environment. Despite this, NASA sought to promote a bold vision of a Shuttle-launched future. Image credit: NASA.

The National Commission on Space (NCOS) began its planned year-long study on 29 March 1985. Reagan tapped Apollo-era NASA Administrator Thomas Paine to head up the Commission. Among its commissioners were such aviation and spaceflight luminaries as first moonwalker Neil Armstrong, Chuck Yeager, the first person to fly faster than sound, and Kathryn Sullivan, the first U.S. woman to walk in space.

The NCOS report, titled Pioneering the Space Frontier, reached the news media in March 1986. Paine formally presented it to the White House and Congress on 22 July 1986. It called for a 50-year program that included fully reusable shuttles, heavy-lift rockets, an Earth-orbiting spaceport, a variable-gravity space station for biomedical research, lunar oxygen mines, cycling Mars liners, an outpost on inner martian moon Phobos, and a science base on Mars. It touched on topics as wide-ranging as self-replicating space factories, submersibles for the hypothetical world-ocean of Uranus, and U.S. involvement in the International Space Year of 1992.

Set against the backdrop of the Challenger accident and NASA's revealed weaknesses, the NCOS program appeared at best grandiose. The Reagan Administration quietly shelved the NCOS report.

Concern over NASA's long-term direction had, however, not abated. If anything, it had increased, in part because the Soviet Union had launched its long-awaited Mir core space station (20 February 1986). Many feared that the U.S. civilian space agency had lost not only its sense of direction, but also its place as the world leader in spaceflight.

On 18 August 1986, less than a month after the NCOS report reached Congress and the White House, NASA Administrator James Fletcher appointed Sally Ride, the first U.S. woman in space, as his Special Assistant for Strategic Planning. He charged her with preparing a new blueprint for NASA's future — one more focused and readily achievable than the NCOS blueprint — that would emphasize specific ways that NASA could demonstrate U.S. leadership in space.

Robotic Mars missions would have played significant roles in both the Collins Task Force piloted Mars program and Sally Ride's robotic Solar System exploration "leadership initiative." Image credit: NASA.

While drafting her report, Ride received input in the form of a three-and-a-half-page paper from the NASA Space Goals Task Force, a 12-member group appointed by NASA Advisory Council chairman Daniel Fink and chaired by Apollo 11 Command Module Pilot Michael Collins. The Council gave the Collins Task Force final report its blessing during its 3-4 March 1987 meeting, and Fink submitted the report to Fletcher to pass on to Ride on 16 March.

The Space Goals Task Force declared that a "bold goal, clearly stated" would help the space agency to "focus and clarify" its long-term objectives. Mars, the Task Force report continued, stood out as "the one entity most likely to capture widespread enthusiasm and support, while pulling considerable scientific and technical capability in its wake." It called for a public declaration that astronauts "exploring and prospecting on Mars" would henceforth become NASA's "primary goal."

The Task Force then outlined "preliminary steps" that the U.S. would need to take before Americans could take steps on Mars. First, the Space Shuttle would need to resume operations and new expendable rockets would need to be developed to supplement it. This would help to ensure uninterrupted U.S. space access. Funding for space technology research would need to be increased to reverse the "serious erosion of our technology base" that began during the Nixon Administration. In addition, an "aggressive" program of robotic Mars missions would be required.

NASA would also need to complete the Space Station as soon as possible so that it could serve as a test-bed for the development of Mars Program technologies and a laboratory for studying long-duration spaceflight effects on human physiology. "The Space Station is an element of human expansion [into space] in its own right," the Task Force declared, "but it is far more important because of its essential role in building the capability to conduct programs that achieve and demonstrate [space] leadership."

One of many piloted Mars lander designs proposed in the mid-to-late 1980s — the "molly bolt" configuration. Image credit: Eagle Engineering/NASA.

When Americans set foot on Mars, the Task Force continued, it should be as part of a "peaceful enterprise done in the name of all humankind." It asserted, in fact, that American Mars explorers should, "[u]nder appropriate conditions," be accompanied by astronauts of other "qualified nations," including the Soviet Union.

The Task Force called for "a realistic schedule" for its Mars Program that would ensure "stable planning and execution of a studied, orderly, progressive series of events." As part of the effort to develop a schedule, NASA, the President, and the Congress would need to decide "whether the Moon should be used as stepping stone to Mars, or should be bypassed."

It concluded by considering commercial opportunities that the Mars Program might create. NASA would "pull" commercial space ventures into existence through its revitalized research programs, the Collins Task Group report argued, adding that the "history of this Nation is replete with examples of successful commercial activity stimulated by the technologies resulting from the exploration of new frontiers." "The technical challenges associated with a program of human exploration of Mars are of such a magnitude," it continued, that they would "certainly provide many direct and indirect stimuli to American industry."

The Space Goals Task Force report influenced Sally Ride's August 1987 report Leadership and America's Future in Space, though she gave equal emphasis to four leadership initiatives (Earth studies, robotic Solar System exploration, an outpost on the Moon, and humans to Mars). She argued that the U.S. could not demonstrate space leadership in all areas of spaceflight endeavor, so should choose one or two and excel in them. She also stated - in testimony before Congress on her report - that she believed that NASA should return astronauts to the Moon before accepting the greater challenge of astronauts on Mars.

Collins, probably the most articulate of the astronaut writers, subsequently sought to build support for the Mars-centered Space Goals Task Force program. In a prominent article in the November 1988 issue of the widely circulated National Geographic magazine and in his 1990 book Mission to Mars, he called upon NASA to bypass the Moon and launch humans to Mars as early as 2004.

Sources

Letter with enclosure, Daniel J. Fink to James C. Fletcher, "NASA Space Goals Task Force Final Report," 16 March 1987.

"Mission to Mars," Michael Collins, National Geographic, Volume 174, November 1988, pp. 732-764.

Mission to Mars: An Astronaut's Vision of Our Future in Space, Michael Collins, Grove Press, 1990.

Humans to Mars: Fifty Years of Mission Planning, 1950-2000, David S. F. Portree, Monographs in Aerospace History #21, NASA SP-2001-4521, February 2001, pp. 68-69.

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