Revival: A Piloted Mars Flyby in the 1990s (1985)

An Orbital Transfer Vehicle (OTV) carrying a drum-shaped Command Module aerobrakes in Earth's atmosphere in this NASA painting by Pat Rawlings. 
In the 1960s, NASA expended nearly as much study money and effort on piloted Mars and Venus flyby mission planning as it did on its more widely known plans for piloted Mars landings. Italian aviation and rocketry pioneer Gaetano Crocco had described a free-return piloted Mars/Venus flyby mission in 1956. Piloted flyby studies within NASA began with the EMPIRE study the Marshall Space Flight Center (MSFC) Future Projects Office initiated in 1962 and culminated in the NASA-wide Planetary Joint Action Group (JAG) piloted flyby study of 1966-1967.

The Planetary JAG, led by the NASA Headquarters Office of Manned Space Flight, brought together engineers from MSFC, Kennedy Space Center, the Manned Spacecraft Center (MSC), and Washington, DC-based planning contractor Bellcomm. It issued a Phase I report in October 1966 and continued Phase II study work in Fiscal Year (FY) 1967. The Phase I report emphasized a piloted Mars flyby mission in 1975, but included Mars and Venus flyby missions tailored to low-energy mission opportunities through 1981. All would be based on hardware developed for the Apollo Program and its planned successor, the Apollo Applications Program (AAP).

The piloted flyby spacecraft would carry automated probes, including one that would land on Mars, collect a sample of surface material and launch it back to the flyby spacecraft for immediate analysis. A leading point in favor of the piloted flyby mission was, in fact, the ability of the flyby crew to examine a Mars sample for signs of life less than an an hour after it left the martian surface.

Red planet off the port bow: a piloted flyby spacecraft based on Apollo spacecraft hardware releases probes as it passes Mars. Image credit: Douglas Aircraft Company.
According to Edward Clinton Ezell and Linda Neumann Ezell, writing in their 1984 NASA-published history On Mars: Exploration of the Red Planet, 1958-1978, NASA MSC was largely responsible for the demise of 1960s piloted flyby mission planning. On 3 August 1967, the Houston, Texas-based center, home of the astronaut corps and Mission Control, distributed to 28 aerospace companies a Request for Proposal (RFP) for a piloted Mars flyby spacecraft sample-returner design study. By doing this, MSC appeared to disregard warnings from Congress that no new NASA program starts would be tolerated.

In the summer of 1967, NASA was preoccupied with recovery from the 27 January 1967 Apollo 1 fire, which had killed astronauts Virgil Grissom, Roger Chaffee, and Ed White. Many in Congress felt that NASA had been lax in enforcing quality and safety standards at North American Aviation, the Apollo Command and Service Module spacecraft prime contractor, so deserved to be "punished" for the accident. Other members of Congress were angered by NASA's apparent failure to share its concerns regarding NAA's performance so they could exercise Congressional oversight. They did not, however, wish to cut Apollo funding and endanger accomplishment of Apollo's very public goal of a man on the Moon by 1970.

In addition, by August 1967, the Federal budget deficit for FY 1967 had reached $30 billion. Though negligible by modern standards, this was a shocking sum in 1967. The deficit was driven in large part by the cost of fighting in Indochina, which had reached more than $2 billion a month, or the entire Apollo Program budget of $25 billion every 10 months.

After learning of the MSC RFP, long-time House Space Committee Chair and NASA supporter Joseph Karth declared angrily that "a manned mission to Mars or Venus by 1975 or 1977 is now and always has been out of the question — and anyone who persists in this kind of misallocation of resources. . .is going to be stopped." On 16 August, the House cut all funding for advanced planning from NASA's FY 1968 budget bill and slashed the budget for AAP from $455 million to $122 million. Total cuts to President Lyndon Baines Johnson's January 1967 FY 1968 NASA budget request amounted to more than $500 million, or about 10% of NASA's FY 1967 budget total.

Though he opposed the cuts, President Johnson bowed to the inevitable and signed the budget into law. The Planetary JAG and Bellcomm tied up loose ends of the piloted flyby study during FY 1968, but most work on the concept ended within a few months of the Houston center's ill-timed RFP.

It is ironic, then, that NASA's next piloted Mars flyby study took place in Houston, at Johnson Space Center (JSC), as MSC had been re-christened following President Johnson's death in January 1973. Barney Roberts, an engineer in the JSC Engineering Directorate, reported on the study to the joint NASA-Los Alamos National Laboratory (LANL) Manned Mars Missions workshop in June 1985.

The workshop, held at NASA MSFC, was a significant step in the revival of piloted Mars exploration planning within NASA after the long drought of the 1970s. Unfortunately, in their plan for a piloted Mars flyby in the 1990s, NASA JSC engineers demonstrated little sign of awareness of the 1960s piloted flyby studies. As a result, their proposed mission was less credible than it might have been.

Roberts explained that the NASA JSC flyby plan aimed to counter a possible Soviet piloted Mars flyby. He cited a 1984 Central Intelligence Agency (CIA) memorandum that suggested (without citing much in the way of evidence) that the Soviet Union might attempt such a mission in the 1990s — possibly as early as the 75th anniversary of the Bolshevik Revolution in 1992 — in order to garner international prestige. The CIA study had been performed at the request of Apollo 17 moonwalker Harrison Schmitt, whose chief spaceflight interest in the early-to-mid 1980s was a piloted Mars mission.

NASA's piloted Mars flyby would be based on space hardware expected to be operational and readily available in the late 1990s. Space Shuttle Orbiters would deliver to NASA's Space Station an 18-ton Mission Module (MM) and a pair of expendable propellant tanks with an empty mass of 11.6 tons each. The MM, derived from a Space Station module, would carry a 3000-pound solar-flare radiation shelter, 7000 pounds of science equipment, and 2300 pounds of food and water.

Going for a ride: a piloted Mars flyby spacecraft prepares for launch from Earth orbit in the late 1990s. A = twin Orbital Transfer Vehicles (OTVs); B = twin strap-on propellant tanks; C = Command Module; D = Mission Module. Image credit: NASA/David S. F. Portree.
The MM would be docked to a six-ton Command Module (CM) and two 5.75-ton Orbital Transfer Vehicles (OTVs). The OTVs would each include an aerobrake heat shield and two rocket engines derived from the Space Shuttle Main Engine. The JSC engineers had assumed that the CM and OTVs would be in space already as part of a late 1990s NASA Lunar Base Program. The strap-on tanks would be joined to the MM/CM stack by trunnion pins similar to those used to anchor payloads in the Space Shuttle Orbiter payload bay, then Space Station astronauts would perform spacewalks to link propellant pipes and electrical and control cables.

Shuttle-derived heavy-lift rockets would then deliver a total of 221 tons of cryogenic liquid hydrogen and liquid oxygen propellants to the Space Station to fill the piloted flyby spacecraft's twin tanks. The propellants would be pumped aboard just prior to departure from Earth orbit to prevent liquid hydrogen loss through boil off. Mass of the piloted flyby spacecraft at the start of its Earth-departure maneuver would total 358 tons.

As the launch window for the Mars flyby opportunity opened, the piloted flyby spacecraft would move away from the Space Station using small thrusters on retractable arms, then the four OTV engines would ignite and burn for about one hour to put it on course for Mars. The only propulsive maneuver of the baseline mission, the burn would empty the OTV and strap-on propellant tanks. Roberts advised retaining the spent tanks to serve as shielding against meteoroids and radiation for the MM and CM during the year-long flight.

Roberts told the workshop that the flyby spacecraft would spend two-and-a-half hours within about 20,000 miles of Mars. Closest approach would bring it to within 160 miles of Mars. At closest approach, the spacecraft would be moving at about 5 miles per second.

The spacecraft would then begin its long return to Earth. Roberts provided few details of the interplanetary phases of his piloted Mars flyby mission.

As Earth grew from a bright star to a distant disk, the Mars flyby astronauts would discard the twin strap-on tanks. They would then undock one OTV by remote control and re-dock it to the front of the CM. After entering the CM and sealing the hatch leading to the MM, they would discard the MM and second OTV, then would then strap into their couches to prepare for aerobraking in Earth's upper atmosphere and capture into Earth orbit. After the OTV/CM combination completed the aerobraking maneuver, the crew would pilot it to a docking with the Space Station.

Almost home: the piloted Mars spacecraft prepares for the aerobraking maneuver in Earth's atmosphere at the end of its epic year-long interplanetary voyage. A = OTVs; C = Command Module bearing crew; D = discarded Mission Module (attached to discarded OTV). Image credit: NASA/David S. F. Portree.
Roberts told the NASA/LANL workshop that Earth return would be the most challenging phase of the piloted Mars flyby mission. The OTV/CM combination would encounter Earth's upper atmosphere at a speed of 55,000 feet (10.4 miles) per second, producing reentry heating well beyond the planned capacity of the OTV's heat shield. In addition, the crew would suffer "exorbitant" deceleration after living for a year in weightlessness.

Roberts proposed a "brute-force" solution to these problems: use the OTV's twin rocket motors to slow the OTV/CM to lunar-return speed of 35,000 feet (6.6 miles) per second. The braking burn would, however, increase the Mars flyby spacecraft's total required propellant load to nearly 500 tons. He calculated that, assuming that a Shuttle-derived heavy-lift rocket could be designed to deliver cargo to LEO at a cost of $500 per pound (an optimistic assumption, as it would turn out), then Earth-braking propellant would add $250 million to his mission's cost.

Roberts briefly considered partially compensating for the large mass of braking propellants by substituting an MM derived from a five-ton Space Station logistics module for the 18-ton MM. This would mean, however, that the crew would have to spend a year in cramped quarters with no exercise or science equipment.

Planners in the 1960s had wrestled with and prevailed over the same problems of propellant mass and Earth-return speed that NASA JSC engineers faced in their 1985 study. Bellcomm had, for example, proposed in June 1967 that the Planetary JAG's piloted Mars flyby mission conserve propellants through assembly of the flyby spacecraft in an elliptical orbit, not circular Space Station orbit. The elliptical assembly orbit would mean, in effect, that the flyby spacecraft would begin Earth-orbit departure even as it was being assembled.

In addition, returning the crew directly to Earth's surface in a small Apollo-type capsule with a beefed-up heat shield would greatly reduce the quantity of braking propellants required; it could eliminate the braking maneuver entirely. It would also enable an aerodynamic "skip" maneuver that would reduce deceleration stress on the astronauts.

TRW Space Technology Laboratory had proposed as early as 1964, during the EMPIRE follow-on studies, that NASA use a Venus flyby to slow spacecraft returning from Mars. Crocco had described the concept in 1956, in fact, though in a form that turned out to be unworkable because of errors he made when he calculated his flyby spacecraft's orbit about the Sun.

Exploiting a Venus flyby to reduce speed would, of course, limit Earth-Mars-Earth transfer opportunities to those that would intersect Venus on the return leg, but would also eliminate the costly end-of-mission braking burn and enable Venus exploration as a bonus. The Planetary JAG's October 1966 report described Mars-Venus and Venus-Mars-Venus flyby missions in the late 1970s. Bellcomm determined in late 1966 and 1967 that Mars/Venus flyby opportunities are not rare.

Sources

"Soviet Plans for a Manned Flight to Mars," C. Cravotta and M. DeForth, Office of Scientific and Weapons Research, Central Intelligence Agency, 2 April 1985.

"Concept for a Manned Mars Flyby," Barney B. Roberts, Manned Mars Missions: Working Group Papers, Volume 1, NASA M002, NASA/LANL, June 1986, pp. 203-218; proceedings of a workshop held at NASA Marshall Space Flight Center, Huntsville, Alabama, 10-14 June 1985.

On Mars: Exploration of the Red Planet, 1958-1978, NASA SP-4212, Edward Clinton Ezell & Linda Neuman Ezell, NASA History Office, 1984, pp. 117-118.

Humans to Mars: Fifty Years of Mission Planning, 1950-2000, Monographs in Aerospace History #21, NASA SP-2001-4521, David S. F. Portree, NASA History Division, February 2001, pp. 11-12, 15, 60-62.

More Information

After EMPIRE: Using Apollo Technology to Explore Mars and Venus (1965)

Relighting the FIRE: A 1966 Proposal for Piloted Interplanetary Mission Reentry Tests

Apollo Ends at Venus: A 1967 Proposal for Single-Launch Piloted Venus Flybys in 1972, 1973, and 1975

Triple Flyby: Venus-Mars-Venus Piloted Flyby Missions in the Late 1970s/Early 1980s (1967)

Astronaut Telescope Servicing at Earth-Sun L2 (1999)

Interplanetary space showing the positions of the Sun, Earth, Earth's orbit about the Sun, the Moon, the Moon's orbit about the Earth, and the five Earth-Sun Libration Points. Image credit: NASA.
The Earth-Moon and Sun-Earth Libration (L) points are not places in the sense that one can land on them and pick up rocks. Because of this, some space exploration planners perceive them to be unsatisfying destinations. The L points have, however, long been proposed as space transportation way stations and as radio relay and scientific instrument sites.

In 1999, the Decadal Planning Team (DPT), a secretive NASA-wide study group chartered by President William Clinton's Office of Management and Budget, identified astronomical observatories in "halo orbits" around the Sun-Earth L points as a key NASA goal for the early 21st century. These large and complex instruments would, among other tasks, seek to observe Earth-like worlds around other stars.

The NASA Exploration Team (NExT), the DPT's immediate successor, subsequently sought to incorporate the Sun-Earth L point emphasis into its piloted spaceflight planning. In a 20 December 1999 presentation to the NeXT, for example, NASA Johnson Space Center exploration planner Bret Drake examined ways that the Sun-Earth L points might aid future piloted Mars missions.

An automated solar observatory orbiting the Sun-Earth L1 point, 1.5 million kilometers from Earth in the direction of the Sun, could provide Mars crews with early warning of solar flares, Drake explained. Radio relays in halo orbit about Sun-Earth L4, 60° ahead of the Earth along its Sun-centered orbit, and Sun-Earth L5, 60° behind the Earth along its orbit, could enable continuous radio communication between Earth and crews exploring Mars during superior conjunctions, when the Sun blocks line-of-sight radio contact between the two planets.

Drake hastened to add that the Sun-Earth L points would not be good staging places for piloted Mars missions. He explained that the trip to and from a Sun-Earth L point would add almost two months to the typical duration of a roundtrip Mars voyage that started from low-Earth orbit (LEO).

Piloted missions to Sun-Earth L points might, however, serve as experience-building intermediate steps between piloted LEO missions and piloted Mars missions. Drake suggested that L point missions could enable astronauts to experience interplanetary conditions (for example, solar radiation undiminished by Earth's magnetic field), yet would have one-way trip times as short as 25 days.

Drake proposed that NASA astronauts carry out a 100-day telescope-servicing mission to Sun-Earth L2, 1.5 million kilometers from Earth in the direction opposite the Sun. The mission would employ Solar-Electric Propulsion (SEP) technologies and techniques first proposed in 1998 for NASA's Mars Design Reference Mission.

The mission would begin with the unmanned launch to LEO of a 32,975-kilogram telescope-servicing spacecraft comprising a 14,450-kilogram inflatable "mini-Transhab" crew module, a 4271-kilogram Apollo Command Module-shaped Earth Return Vehicle (ERV), and a 14,164-kilogram two-stage Chemical Propulsion Module. The spacecraft would reach LEO within the streamlined shroud of a next-generation expendable rocket called an Evolved Expendable Launch Vehicle-Heavy (EELV-H).

A Space Shuttle Orbiter would rendezvous with the telescope-servicing spacecraft in LEO so that astronauts could oversee inflation of the doughnut-shaped single-deck mini-Transhab and deployment of its twin electricity-generating solar arrays. They would install equipment and furnishings in the mini-Transhab and stock it with supplies, then would return to Earth.

A second EELV-H would place a 33,000-kilogram automated Solar-Electric Propulsion (SEP) Vehicle into LEO, where it would automatically deploy solar-array wings and dock with the telescope-servicing spacecraft. Over the next seven months, the SEP Vehicle would operate its electric-propulsion thrusters at perigee (the low point in its orbit about the Earth) to raise its apogee (the high point in its orbit).

The result of these SEP Boost Phase maneuvers would be a highly elliptical orbit loosely bound to the Earth. The SEP Vehicle would then detach from the telescope-servicing spacecraft and operate its thrusters at apogee to return to LEO for refurbishment and reuse.

Use of the SEP Vehicle to place the telescope-servicing spacecraft into a highly elliptical Earth orbit would dramatically reduce the quantity of chemical propellants required to leave LEO for Earth-Sun L2. SEP thrusters produce little thrust but can do so over long periods and expend little propellant. This approach would greatly reduce overall mission mass and the number of EELV-H and Shuttle Orbiter flights required to place the telescope-servicing spacecraft into LEO.

The telescope-servicing spacecraft would carry no crew during the SEP Boost Phase because it would pass through Earth's radiation belts repeatedly. Over time, this would subject the crew to an unacceptably high cumulative radiation dose.

Drake inserted into his telescope-servicing mission assembly-and-launch sequence an optional piloted mission that would fly only if the telescope-servicing spacecraft needed repairs following the SEP Boost Phase. A Shuttle Orbiter would deliver to LEO a maintenance crew, a small lifting-body Crew Taxi, and a chemical-propulsion rocket stage. The stage would rapidly boost the Taxi into a highly elliptical Earth orbit matching that of the telescope-servicing spacecraft.

The maintenance crew would rendezvous and dock with the telescope-servicing spacecraft. After completing the needed repairs, they would undock, fire the Crew Taxi's rocket motors at apogee to lower its perigee into Earth's atmosphere, perform reentry, and glide to a landing.

If, however, flight controllers on Earth determined that the telescope-servicing spacecraft in highly elliptical Earth orbit was healthy and that no repairs were needed, the Crew Taxi would deliver a four-person crew to the telescope-servicing spacecraft. After casting off the Taxi, they would ignite the telescope-servicing spacecraft's first chemical-propulsion stage at perigee to escape their loosely bound highly elliptical orbit and begin the 25-day voyage to Sun-Earth L2. They would then cast off the spent stage.

In the Sun-Earth L2 Operations Phase, the telescope-servicing spacecraft would enter a "halo parking orbit" centered on Sun-Earth L2. For 50 days the astronauts would service large next-generation telescopes in halo orbits around Sun-Earth L2, much as Space Shuttle crews in 1993, 1997, 1999, 2002, and 2009 serviced the Hubble Space Telescope in LEO. Drake suggested that during their down time between servicing calls they might conduct unspecified scientific research.

Their mission completed, the astronauts would ignite the second stage of the telescope-servicing spacecraft's Chemical Propulsion Module to begin return to Earth. About 25 days later, they would strap into the ERV capsule, undock from their home of the previous 100 days, reenter Earth's atmosphere, and parachute to a landing. The other components of the telescope-servicing spacecraft would burn up in Earth's atmosphere.

Even as Drake presented his Earth-Sun L2 servicing mission concept, NASA engineers conceived of a Gateway space station in halo orbit about Earth-Moon L1 as a base for observatory servicing and as a stepping stone to points all over the lunar surface. They envisioned that observatories needing servicing would ignite small thrusters to begin a slow transfer from their Earth-Sun L1 and L2 halo orbits to the vicinity of the Gateway. Once at Earth-Moon L1, they would be serviced by spacewalking astronauts, "cherry picker" booms, and teleoperated systems.

Flying formation with teleoperated systems, an advanced space telescope arrives in the vicinity of the Earth-Moon L1 Gateway. The twin red spheres carry imagers that supply information on the telescope to astronauts inside the Gateway. As they escort the telescope, a boxy teleoperated robot with several jointed appendages moves into the shadow cast by its multi-layer sunshield. Partially silhouetted against the Moon, the Gateway includes six solar arrays, a doughnut-shaped pressurized mini-Transhab habitat module, multiple docking ports, servicing equipment, and three rocket stages for unspecified missions. Please click on the image to enlarge. Image credit: NASA.
Cislunar space showing the positions of Earth, the Moon, the Moon's orbit about Earth, and the five Earth-Moon Libration Points. Image credit: NASA.
In January 2004, in the aftermath of the STS-107 Columbia Space Shuttle accident (1 February 2003) and at the start of the 2004 election cycle, President George W. Bush called for a new NASA program to take humans to the Moon and Mars. At first, the Vision for Space Exploration (VSE), as it became known, incorporated many elements of DPT/NExT.

Soon after Michael Griffin became NASA Administrator on 13 April 2005, however, the VSE veered away from DPT/NExT and toward the Constellation Program, which Griffin called "Apollo on steroids." Bush showed little interest in the VSE after he announced it, so did not intervene to keep his program on track.

Constellation and the VSE were mostly abandoned in 2009-2010 under President Barack Obama. The global economy was in crisis following the collapse of the U.S. housing market in 2008 and the near-collapse of the global financial system. Spaceflight, rarely a high priority, took a distant back seat to repairing the U.S. economy.

When Obama unveiled a new space plan in 2010, it resembled DPT/NExT more than Constellation. The Bush Administration's decision to cancel the Space Shuttle led to the most significant deviation from the DPT/NExT architecture: retention of Constellation's large rocket under the name Space Launch System. Resembling an oversized EELV-H, SLS replaced the Shuttle Orbiter and the solar-electric tug of the DPT/NExT plan. The Orion Crew Exploration Vehicle (CEV) replaced the lifting-body taxi.

Meanwhile, China launched a program to explore the Moon using robots. Chang'e 1 orbited the Moon in 2007-2009; Chang'e 2 orbited the Moon in 2010-2012 before leaving lunar orbit for a flyby of the Near-Earth Asteroid 4179 Toutatis; and Chang'e 3 landed on the Moon in late 2013.

Chang'e 4, targeted for the lunar farside hemisphere, landed successfully in January 2019. It transmits radio signals to Earth via the Queqiao satellite, which reached a halo orbit around Earth-Moon L2 in June 2018. In addition to relaying signals from Chang'e 4 and its rover to Earth, Queqiao also serves as a radio observatory remote from the radio noise of Earth.

A radio-relay satellite in Earth-Moon L2 halo orbit enables communication with spacecraft out of line-of-sight radio contact on the hidden farside hemisphere of the Moon. Image credit: NASA.
Sources

"Future Missions for Libration-point Satellites," R. Farquhar, Astronautics & Aeronautics, May 1969, pp. 52-56.

"Strategic Considerations for Cislunar Space Infrastructure," IAF-93-Q.5.416, W. Mendell and S. Hoffman; paper presented at the 44th Congress of the International Astronautical Federation, 16-22 October 1993.

"Representative Human Missions to the Sun-Earth Libration Point (L2) '100' Day Class Mission," SEL2 Ver. R, Bret G. Drake, NASA Johnson Space Center, presentation materials, 20 December 1999.

"'Invisible Planets' Gain Favor as Real Estate in Space," L. David, Space.com, 19 January 2000.

More Information

Solar Flares and Moondust: The 1962 Proposal for an Interdisciplinary Science Satellite at Earth-Moon L4

Lunar GAS (1987)

Apollo Science and Sites: The Sonett Report (1963)

Apollo 17 Lunar Module Pilot Harrison Schmitt, a geologist, was the only professional scientist to reach the Moon. Image credit: NASA.
The Apollo Program was driven by the perceived national need to decisively demonstrate American technological prowess in the face of early Soviet space victories. Scientific lunar exploration was a secondary concern. In fact, some engineers saw lunar science as a distraction from the already daunting task of landing a man on the Moon and returning him safely to Earth.

The community of lunar scientists was small in May 1961, when President John F. Kennedy put the U.S. on the road to the Moon. Nevertheless, lunar science had its energetic proponents. In early 1962, they saw to it that NASA's Office of Manned Space Flight (OMSF) asked NASA's Office of Space Science (OSS) to outline an Apollo science program. OSS appointed NASA physicist Charles Sonett to head up an ad hoc working group and OMSF provided the group with guidelines for its deliberations.

The Sonett group's 12 members and nine consultants included U.S. Geological Survey geologist (and aspiring astronaut) Eugene Shoemaker, astronomers Gerard Kuiper and Thomas Gold, NASA geophysicist Paul Lowman, and chemist (and Nobel Laureate) Harold Urey. They circulated their July 1962 draft report at the National Academy of Science's 10-week Iowa City meeting (17 June-31 August 1962) and within NASA, receiving, they reported, "general endorsement" for their recommendations.

The final version of the Sonett report, published in December 1963 and labeled "for internal NASA use only," was the first in a series of influential Apollo planning documents that called for ambitious scientific exploration of the Moon. Its recommendations touched on many aspects of Apollo mission planning.

The Sonett group called for all proposed Apollo landing sites to be photographed by automated Lunar Orbiter spacecraft before final site selection. Lunar Orbiter photographs would be used to make detailed geological maps of planned landing sites. This, the Sonett group's members argued, would save precious time during Apollo landing missions, because it would enable astronauts to begin geological field work without first mapping their landing site.

They urged that every two-person Apollo landing crew include a scientist-astronaut with a Ph.D. in geology and from five to 10 years of field experience. Geologists on Earth would explore the Moon vicariously through his descriptions and through real-time television transmitted from a camera mounted on his space suit.

They acknowledged that Kennedy's end-of-decade deadline for reaching the Moon meant that Apollo scientist-astronauts would probably be drawn from the community of scientists already at work in 1962-1963. They assumed, however, that Apollo would be merely the first U.S. program of piloted lunar exploration, so urged that "graduate students and young post graduate scientists. . .be brought into the field of lunar science as potential astronauts as soon as possible."

OMSF had advised the Sonett group that the Apollo lunar surface space suit would "limit the crew's ability to act, particularly in performing precise manipulations." In their final report, the group's members, undaunted by anticipated technological limitations, urged early development of surface suits that would "permit a close approximation to unsuited limb, arm, and digital [finger] movements."

Sonett working group member Eugene Shoemaker models a pressure suit proposed for advanced Apollo Extension System lunar exploration missions. He stands outside the hatch of a mockup long-range lunar rover. Image credit: U.S. Geological Survey.
OMSF also told the group that a space-suited Apollo astronaut would probably be unable to walk more than a half-mile from his lunar lander, but raised the possibility of a rover or other mobility aids. The Sonett group declared that
. . .reconnaissance beyond a one-half mile radius of the spacecraft will be a necessity. . .For example, a lunar ray, a feature of great interest, is probably a poor place to land, yet the capability of traveling to a ray area is clearly indicated. . .For scientific purposes, therefore, there should be the capability of reaching areas some 50 miles from a landing site.
In 1962-1963, OMSF considered development of an automated lander capable of delivering to the Moon up to 15 tons of equipment and supplies. In addition to a beacon for guiding an Apollo Lunar Excursion Module (LEM) piloted lander to a safe touchdown nearby, it would carry one or more rovers and expendables — for example, liquid and gaseous oxygen — for extending LEM electricity-generation and life-support capabilities. The Sonett group urged OMSF to proceed with cargo lander development, noting that the LEM as planned would carry supplies and equipment inadequate to accomplish "even the modest scientific program recommended."

The Apollo LEM lander and lunar surface space suit as envisioned in 1964. Image credit: NASA.
OMSF informed the Sonett working group that the first Apollo lunar surface mission would probably spend only four hours on the Moon. The group urged OMSF to double that stay time so the astronauts could budget four hours for operational activities (for example, checking out their LEM before departing the Moon) and four hours for exploring the lunar surface. During their lunar traverses, they would take turns moving beyond the immediate vicinity of the LEM, collect up to 100 pounds of rocks, test soil strength, and study whether solar heating caused Moon dust to flow like a highly viscous liquid, as hypothesized by Sonett group member Thomas Gold.

The group acknowledged that "an accident" might limit surface exploration during the first Apollo landing mission to one hour. In that case, a single moonwalker would hurriedly collect about 50 pounds of geological samples near the LEM.

The group's members envisioned a five-day Apollo mission with four days of uninterrupted exploration, during which the two astronauts would drive a rover up to 10 miles from their landing site. They would also drill a hole up to 20 feet deep and insert a heat probe, collect samples "for biological purposes," and emplace a seismometer, a micrometeorite detector, and other instrument packages. They expected that the instruments would be linked by cables to a "central station" containing a radio transmitter. This would use a nuclear source to generate electricity so that it could relay data from the instruments to Earth for months or years.

OMSF asked the Sonett working group to assume "more than one but less than ten" Apollo landings. Apollo landings would, OMSF explained, be limited to sites near the equator on the side of the Moon that faces Earth. The Sonett group recommended that the first Apollo piloted lander set down near Copernicus crater.

Sonett group member Eugene Shoemaker was probably behind the Copernicus site choice; he had spent a great deal of time studying the crater starting in the late 1950s as part of his effort to resolve the debate over whether lunar craters were primarily the result of volcanism or of asteroid impacts and to establish the stratigraphic sequence of the Moon's geologic units. The latter was a requirement if the history of the lunar surface would be deciphered.

Copernicus, a leading Sonett group Apollo landing site candidate, as portrayed in an early 1960s map. Moon maps in this series, based on photos from Earth-based telescopes, were the best available at the time the Sonett Group wrote its report. Image credit: Lunar and Planetary Institute. 
In keeping with their conviction that lunar exploration should continue beyond Apollo, the Sonett group scientists offered two lists with a total of 28 candidate landing sites. All sites were selected using photographs taken using Earth-based telescopes.

The first list of 15 sites, compiled in June 1962 by Eugene Shoemaker and R. E. Eggleton, another U.S. Geological Survey geologist, took into account "possible landing conditions and trafficability, and prospects of discovering natural shelter and potential water supplies."
  • 9.8° North (N), 20.1° West (W), near the Copernicus central peaks
  • 13.1° N, 31° W, on a "typical lunar dome" near the crater Tobias Mayer
  • 20.4° N, 3° W, on the southeast edge of Mare Imbrium, near Mt. Huyghens in the Apennine Mountains
  • 12.6° N, 2° W, in Alphonsus crater, site of suspected on-going lunar volcanism
  • 7.7° N, 6.3° East (E), within four-mile-wide Hyginus ("one of the largest craters of likely volcanic origin"), located at a potentially significant bend in Hyginus Rille
  • 37.9° N, 16.4° W, near a "possible flow" in Mare Imbrium
  • 40.9° South (S), 11.1° W, on the "rubbly" north flank of the great ray crater Tycho
  • 50.6° S, 60.8° W, in Wargentin, an odd lava-filled crater
  • 85° S, 45° E, in the south polar crater Amundsen, where, it was believed, permanently shadowed areas might preserve ice deposits
  • 12.7° S, 49.8° W, on a "very bright" plateau north of the crater Billy
  • 41.7° N, 57.5° W, on Oceanus Procellarum north of the Rumker Hills
  • 5.6° S, 26.6° W, near a "small irregular depression" 35 miles southeast of the crater Hortensius
  • 5.1° N, 14.2° W, on dark material about 140 miles southeast of the center of Copernicus
  • 35.3° N, 5.5° W, on Mare Imbrium near the "mountainous block" Spitzbergen
  • 9.1° S, 16.1° W, on the north flank of crater Parry A, a natural drill hole exposing ancient dark material
The Sonett working group's second list was compiled by geochemist Duane Dugan of NASA's Ames Research Center.
  • 3° S, 44° W, in the middle of the Flamsteed Ring, a mostly submerged crater north of Flamsteed crater
  • 13° S, 2.3° W, in Alphonsus
  • 23.4° N, 43.3° W, near bright Aristarchus crater, flat-floored Herodotus crater, and sinuous Schröter's Rille (a region of suspected on-going lunar volcanism and many apparent volcanic features)
  • 23° N, 51.45° W, inside Herodotus
  • 20.3° N, 3.4° W, on Mare Imbrium west of Mt. Huyghens
  • 28° N, 12° E, on Mare Serenitatis near the unusual crater Linne, site of suspected on-going lunar volcanism
  • 19.3° S, 40.2° W, on safe, flat ground in Mare Humorum near the south wall of dark-floored Gassendi crater
  • 5.5° N, 14.3° W, in a "black" surface area east of Fauth crater
  • 5° S, 28.1° W, in the Ural and Riphaeus Mountains, near "old ghost rings" (submerged craters)
  • 9° S, 2° W, on the floor of Ptolemaeus crater, site of ridges, "craterlets," and a "crater cone" of "remarkable" whiteness
  • 15° N, 22° E, between crater Plinius and the Haemus Mountains, a place "with access to the color discontinuity between Mare Tranquillitatis and Mare Serenitatis"
  • 24.3° S, 43.4° W, in Mare Humorum east of the crater Liebig (site of "an interesting scarp" that cuts through craters)
  • 4.5° S, 25.5° E, in southern Mare Tranquillitatis, at the base of Theophilus crater rim west of Torricelli crater (a "very complex" region with "shading" reminiscent of "one of the terrestrial continental shelves")
That the Shoemaker-Eggleton and Dugan lists had in common only Alphonsus, the dark region near 5.5° N, 14.3° W, and Huyghens-Appenine reflected the wide range of attractive candidate lunar landing sites. Some of the proposed sites, such as Amundsen, lay beyond the equatorial zone OMSF had said Apollo could reach. The working group asserted that "there is no question that sites of the greatest scientific interest lie outside the equatorial belt," and urged that NASA develop the "capability of landing in the equatorial belt, at the poles, and elsewhere."

Alphonsus crater made both the Shoemaker-Eggleton and Dugan lists of candidate Apollo landing sites. Image credit: Lunar and Planetary Institute.
NASA paid attention to the Sonett report and other advice it received from scientists as it planned Apollo missions, but the complex interplay of competing technical, political, and scientific requirements meant that the space agency could give scientists no more than a small fraction of what they desired. Most notably, only one scientist-astronaut reached the Moon: geologist Harrison Schmitt (image at top of post), who explored the Taurus-Littrow valley east of Mare Serenitatis with Eugene Cernan during the Apollo 17 mission (7-19 December 1972).

Schmitt and Cernan spent three days on the Moon. They wore A7LB space suits which restricted their movements, but which were an improvement over the A7L suits worn by Apollo 11, 12, and 14 moonwalkers. They collected drill cores, deployed instruments and a heat-flow probe attached by cables to a nuclear-powered central station, and drove 35.9 kilometers using a jeep-like Lunar Roving Vehicle. All of their equipment arrived stowed on board the Apollo 17 Lunar Module Challenger; NASA developed no automated cargo lander. Apollo 17 returned 110.5 kilograms of geologic samples to researchers on Earth.

Astronauts explored few of the sites Shoemaker, Eggleton, and Dugan selected. The reasons for this were manifold: the U.S. flew only six successful Apollo lunar landing missions; NASA never became capable of landing men very far beyond the Nearside equatorial belt; new knowledge of the Moon from robotic missions and orbiting Apollos made some of the sites appear less scientifically significant than had been believed or less attractive than newly found candidate sites; and no follow-on lunar landing program materialized.

The first Apollo lunar landing mission, Apollo 11 (16-24 July 1969), spent about 21 hours on Mare Tranquillitatis, not in Copernicus; in fact, Copernicus remains unvisited today. Huyghens-Apennine became Hadley-Apennine; visited by Apollo 15 (26 July-7 August 1971), it is widely considered to be the most scientifically significant Apollo site.

Robots explored Alphonsus (Ranger 9, March 1965), the Flamsteed Ring (Surveyor 1, May-July 1966), and Tycho (Surveyor 7, January 1968). The lunar south pole and Aristarchus, as yet unvisited, are frequently mentioned as candidate landing sites for NASA's eventual return to the Moon.

Source

Report of the Ad Hoc Working Group on Apollo Experiments and Training on the Scientific Aspects of the Apollo Program, 15 December 1963. 

More Information

Plush Bug, Economy Bug, Shoestring Bug (1961)

Harold Urey and the Moon (1961)

Apollo Extension System Flight Mission Assignment Plan (1965)

Apollo Extension System Flight Mission Assignment Plan (1965)

NASA piloted spacecraft as conceived in 1964. The rockets at left are the Apollo-Saturn V, the Gemini-Titan, and the Mercury-Atlas. The spacecraft at right are the Apollo CSM/Apollo LEM, Gemini, and Mercury. At the time this was painted, only the one-man Mercury (lower right) had carried an astronaut into orbit. Note the round hatch on the front of the LEM ascent stage (upper right); a square hatch replaced this late in the year. Image credit: D. Meltzer, National Geographic Society/NASA.
On 30 January 1964, President Lyndon Baines Johnson asked NASA Administrator James Webb for a comprehensive list of candidate post-Apollo piloted space programs. At the time, NASA was between Project Mercury, its first piloted program, and Project Gemini, its second. The longest U.S. piloted mission at the time was Mercury-Atlas 9 (15-16 May 1963), which had lasted for 34 hours and 19 minutes. The space agency's top priority was to achieve the goal of a man on the Moon by the end of the 1960s decade.

Webb's response might have included a large Earth-orbiting space station, a lunar base, and a Mars expedition. NASA and its contractors had studied all three by 1964. Instead, his list included just one item: modification of Apollo Command and Service Module (CSM) and Lunar Excursion Module (LEM) spacecraft to provide Earth-orbital and lunar capabilities beyond those planned in the Apollo Program. Because its aim was to extend planned CSM and LEM capabilities, the proposed program was dubbed the Apollo Extension System (AES).

Using spacecraft derived from existing spacecraft to accomplish new missions was, of course, not a new idea. Gemini prime contractor McDonnell proposed a steady stream of Gemini-derived spacecraft beginning in 1962. Gemini had, in fact, started out as a Mercury derivative called "Mercury Mark II."

In 1963, CSM prime contractor North American Aviation (NAA) studied a six-man CSM derivative for delivering space station cargo and changing out station crews. That same year, LEM prime contractor Grumman studied a two-man LEM-derived reconnaissance spacecraft that could fly free of the CSM in lunar orbit, turn cameras toward the lunar surface, and dispense small landing probes.

NASA managers expected that, if all went well, they would have Apollo CSM and LEM spacecraft left over after they achieved Apollo's goal. Surplus Apollo lunar spacecraft would become available for AES missions.

At a press conference, Webb told reporters that he expected NASA's annual budget to climb to about $5.25 billion during Apollo and subsequently remain close to that amount. Funding freed up as Gemini and Apollo wound down would, like the surplus Apollo spacecraft, be shifted to AES, making no new infusion of funds necessary.

Though AES was generally ignored in the rush to develop approved programs like Gemini and Apollo, the proposed post-Apollo program had its critics. Some felt that it was not ambitious enough. The fact was, though, that NASA had enough to do in 1964-1965 without starting a new ambitious program.

Others believed that AES would do nothing in space that needed to be done. In testimony on the Fiscal Year 1966 NASA budget before the House Committee on Space and Astronautics on 18 February 1965, Associate Administrator for Manned Space Flight George Mueller sought to assure legislators that AES was not a "make-work" program. He explained that the Apollo-based program would enable NASA "to perform a number of useful missions. . .in an earlier time frame than might otherwise be expected."

On 29 January 1965, eighteen planners with Bellcomm, NASA's Washington, DC-based Apollo planning contractor, completed an interim report on their study of AES spacecraft and missions. Their eight-part report included a tentative Flight Mission Assignment Plan (FMAP).

In the FMAP, missions were assigned to specific months for planning purposes with the proviso that they would eventually be given precise dates determined by mission objectives, launch constraints, target lighting, and other factors. A chronological list of missions in the January 1965 AES FMAP can be found at the end of this post.

NASA had provided Bellcomm with a preliminary (hence vague) list of AES planning "ground rules" for its study. The first two ground rules taken together were clear: AES should not interfere with or compete with the Apollo Program.

NASA ground rules aimed to contain AES costs by placing restrictions on Apollo spacecraft modification. For example, they specified that CSMs and LEMs manufactured for AES missions were to be delivered to NASA configured for Apollo missions. Spacecraft modification and experiment installation for AES missions would occur outside the NAA and Grumman plants where the CSMs and LEMs were manufactured. In addition, no major facility construction or modification would be allowed; Apollo spacecraft would be converted into AES spacecraft inside buildings where Apollo spacecraft processing occurred.

NASA assured Bellcomm that eight Apollo spacecraft, along with six Saturn IB rockets and six Saturn V rockets, would be available for AES flights each year in the 1969-1971 period. The two-stage Saturn IB was designed for Apollo test missions in low-Earth orbit; the three-stage Saturn V, for boosting Apollo spacecraft to the Moon.

Bellcomm developed additional "guidelines" which it considered "not as firm" as the NASA-provided ground rules. For example, the Bellcomm team decided that all eighteen AES Saturn Vs launched in 1969-1971 should carry astronauts. Of the eighteen, six would launch crews to geosynchronous or polar Earth orbit and the rest would launch crews to the Moon.

The FMAP described 23 AES missions of three types — Earth orbital, lunar orbital, and lunar surface — spanning the period from March 1968 through December 1971. The team proposed eight mission classes within the framework of the three types. Earth-orbital missions included Earth-Oriented, Astronomy, Biomedical/Behavioral, and Operations/Technology classes. Lunar-orbital missions included Equatorial, Inclined, and Polar classes. Lunar-surface missions were of just one class: 14-Day Stays.

Mission difficulty would increase gradually and enough time would be allotted to enable data from one mission of a given class to be used to "optimize" the next mission of that class. Bellcomm cautioned that its list was not meant to include all possible classes, adding that the "catalog of suggested areas of investigation is expanding almost daily."

The Bellcomm engineers expected that, when AES began to fly modified Apollo spacecraft, the program would need one derivative of the Apollo CSM and three Apollo LEM derivatives. The CSM derivative was the Extended CSM (XCSM), the AES workhorse spacecraft. The XCSM would be capable of operating for up to 45 days in space without resupply. Bellcomm saw the XCSM as a "general purpose spacecraft" able to support any AES mission without additional modifications.

Bellcomm noted that design of workable LEM derivatives was problematic. The LEM was evolving rapidly in 1964-1965. In addition, the LEM was inherently more specialized and had more limited design margins than the CSM. Bellcomm described a LEM-Lab, LEM-Shelter, and LEM-Taxi in its January 1965 report, but cautioned that all three derivatives needed more study. Though they put a brave face on it, the Bellcomm engineers were clearly not confident that LEM hardware could be adapted to support all the missions they described.

LEM-Lab with legless descent stage from an October 1965 Grumman study document. The two large structures on either side of the ascent stage are components of a large-format stereo camera. The image at left depicts the LEM-Lab within the segmented Spacecraft Lunar Module Adapter (SLA) shroud. The position of the CSM engine bell within the SLA relative to the top of the LEM-Lab is indicated as an outline. Image credit: Grumman Aircraft Engineering Company.

LEM-Lab without descent stage as depicted in the 1965 Grumman study document. Image credit: Grumman Aircraft Engineering Company. 
The LEM-Lab would have two forms: "ascent-stage-alone" and "ascent-stage-with-descent-stage." Both would depend entirely on the docked XCSM for life support and electricity. In the ascent-stage-with-descent-stage case, the LEM descent engine would augment XCSM propulsion but not attitude control; ascent-stage-alone would rely entirely on the XCSM for propulsion and attitude control. In the text that follows, LEM-Labs are ascent-stage-alone unless otherwise indicated.

At the time the Bellcomm engineers completed their interim study, the LEM ascent stage was expected to include 180 cubic feet of free pressurized volume. To form the LEM-Lab, most LEM ascent stage systems would be stripped out to free up an additional 60 cubic feet of pressurized volume for instruments and experiments in the LEM pressure vessel.

The LEM-Shelter would reach lunar orbit docked to a piloted Apollo CSM, land on the Moon automatically, hibernate on the surface for several months, then provide a two-man crew arriving in a LEM-Taxi with living quarters and exploration equipment for a 14-day lunar surface stay. The LEM-Taxi would be outwardly almost identical to the Apollo LEM, but could be placed in hibernation on the lunar surface for 14 days.

In an attempt to avoid interference with Apollo missions, the Bellcomm engineers built its AES FMAP around an "unofficial" Apollo schedule that saw the first unpiloted Apollo Saturn IB rocket test in January 1966. Bellcomm designated the test SA-201. Two additional Saturn IB test flights would occur, then astronauts would ride to Earth orbit in an Apollo CSM  for the first time atop a Saturn IB in October 1966. Bellcomm called the flight SA-204.

The FMAP also included nine "unassigned" missions for which Saturn rockets were expected to be manufactured, but which would, based on NASA's ground rules, have no Apollo spacecraft to launch. These brought the potential AES mission total to 32.

The first unassigned flight, SA-208, might occur as early as November 1967. Bellcomm explained that the SA-208 Saturn IB might remain in the Apollo Program or might be used to launch a "cislunar" version of the Pegasus micrometeoroid-detection satellite in the AES Program. At the time Bellcomm conducted its study, NASA had on its launch docket for 1965 three Pegasus launches. The first reached orbit less than a month (16 February 1965) after the Bellcomm team completed its AES report.

The next unassigned flight was SA-212 in December 1968. The Bellcomm engineers saw it as another candidate cislunar Pegasus mission. It would be the first cislunar Pegasus mission if SA-208 stayed in the Apollo Program. Other unassigned missions were SA-216 (July 1969), SA-217 (September 1969), SA-220 (April 1970), SA-222 (July 1970), SA-223 (September 1970), SA-224 (November 1970), SA-225 (January 1971), and SA-226 (March 1971).

The original Apollo "buy" included 12 Saturn IB rockets and 15 Saturn V rockets, which meant that SA-212 would be the last flight of an Apollo Saturn IB rocket. NASA would need to order new rockets in 1966 if six Saturn IBs and six Saturn Vs were to be available per year in 1969, 1970, and 1971.

The Bellcomm engineers included five Saturn IB-Centaur upper stage missions in the AES FMAP because Saturn IB-Centaur was nominally under AES management at the time they completed their study. They did not, however, see them as AES missions; they were included for planning purposes. All would carry as payloads automated Voyager Mars/Venus exploration spacecraft (see "More Information" below).

The first Saturn IB-Centaur mission, designated SA-210, would be a Voyager test. It would depart Cape Kennedy in June 1968. The first operational Voyager missions (SA-213/SA-214) would launch to Mars in February/March 1969. A second Voyager pair (SA-227/SA-228) was scheduled for Mars launch in May/June 1971.

The first piloted flight of the AES program would be SA-209 in March 1968. The mission to near-equatorial low-Earth orbit would include two or three astronauts, an unmodified Apollo CSM, and an unmodified Apollo LEM ascent stage with no descent stage. The mission would last from 10 to 14 days. Its crew would focus on engineering experiments, such as pumping propellants in weightlessness and performing spacewalks to test new tools. SA-209 was the first mission in the AES Operations/Technology class.

The first unpiloted Saturn V test (SA-501) would take place as part of the Apollo Program in January 1967. On its third flight (SA-503) in October 1967, the Saturn V would launch its first Apollo crew to Earth orbit.

The first Apollo lunar landing attempt would occur during mission SA-506 in August 1968. If it was successful, then its backup mission (SA-507) might become the first Saturn V-launched AES mission in November 1968. The AES SA-507 mission would see unmodified Apollo CSM and Apollo LEM spacecraft launched to geosynchronous or polar Earth orbit for from 10 to 14 days. Because SA-507 reassignment was tentative, Bellcomm did not specify the mission's class.

If SA-507 stayed within the Apollo Program, then the first AES Saturn V flight (SA-509) would take place in April 1969. Two or three men, an unmodified Apollo CSM, and an unmodified Apollo LEM ascent stage would be launched to geosynchronous Earth orbit for a 10-to-14-day "subsystems development" (Operations/Technology class) mission in preparation for SA-211.

SA-211 in September 1968 would see the first flight of the XCSM and LEM-Lab. The three-man flight in near-equatorial low-Earth orbit, scheduled to last for from 30 to 45 days, would emphasize biomedical/behavioral experiments and would test lunar survey instruments ahead of mission SA-511.

Bellcomm explained that all AES missions would include a biomedical/behavioral component, and all Biomedical/Behavioral-class missions would include at least one other activity. It noted also that AES missions that studied the effects of long-duration spaceflight on astronauts were the most important for future NASA piloted programs.

The Bellcomm engineers might have transferred all Apollo hardware to AES after SA-506 or SA-507 — whichever mission became the first successful Apollo lunar landing mission — but they opted instead to schedule SA-508, SA-510, and SA-512 as Apollo lunar landing missions in February, June, and October 1969. Sandwiched between the February and June Apollo flights, the team scheduled SA-215, an Earth-orbital Apollo CSM/Apollo LEM ascent stage mission intended to test Earth survey instruments (Earth-Oriented class). Between the June and October flights, it scheduled SA-511 (August 1969), the first AES Lunar Orbital Survey mission.

During SA-511, three astronauts would image the Moon from near-equatorial lunar orbit using instruments mounted in a LEM-Lab with a descent stage. The descent stage would help the SA-511 XCSM/LEM-Lab stack maneuver so that it could pass over important lunar surface targets. Bellcomm envisioned that the SA-511 LEM-Lab might release small lunar probes derived from planned Surveyor robotic landers. The mission would last about 35 days, of which about 30 days would be spent in lunar orbit.

In December 1969, a pair of AES missions would lift off, but only one would conclude. SA-513 (Apollo CSM/Apollo LEM ascent stage) was an Operations/Technology-class subsystems development mission like SA-509. It would include three astronauts and operate for from 10 to 14 days in polar Earth orbit. SA-218, on the other hand, would continue — and greatly extend — the biomedical research SA-211 began.

The SA-218 crew would attempt to remain in space for from 60 to 90 days on board an XCSM/LEM-Lab in near-equatorial Earth orbit. They would take an occasional break from gathering data on their own reactions to long-duration spaceflight by testing a "zero-g lab."

In January 1970, NASA would launch SA-219, a three-man XCSM/LEM-Lab mission meant to rendezvous with and resupply SA-218. The Bellcomm team provided little information on how resupply would take place. The SA-218 crew would not return to Earth until March (for the 60-day mission) or April (for the 90-day mission).

Just as SA-218/SA-219 would support a giant leap in space biomedical knowledge, so would SA-514/SA-515 support a giant leap in lunar knowledge. Launched in February 1970 with a crew of two or three, it would see an Apollo CSM transport a LEM-Shelter to the Moon. After insertion into lunar orbit, the LEM-Shelter would separate from the CSM without a crew on board, land automatically at a complex exploration site, and put itself into hibernation.

LEM-Shelter as depicted in the 1965 Grumman study document. Note the rover at right shown in stowed and deployment positions. To the left of the descent stage engine bell, a deep drill is shown in deployed position. Image credit; Grumman Aircraft Engineering Company.
Stylized depiction of the LEM as envisioned in 1964. This image can stand in for the 1964 LEM-Taxi; outwardly, the Apollo LEM and the LEM-Taxi designs were very similar. Image credit: NASA.
In April 1970, SA-515 would reach lunar orbit. The mission would use the last of the 15 Saturn V rockets ordered for Project Apollo. Its payload would comprise an XCSM, LEM-Taxi, and a crew of three.

Two men would descend to a landing near the LEM-Shelter in the LEM-Taxi, then would put the LEM-Taxi in hibernation and transfer to the LEM-Shelter. The LEM-Shelter would carry a small rover, enabling longer geologic traverses than could be achieved during Apollo missions (at the time Bellcomm performed its study, no Apollo mission was expected to carry a rover).

The LEM Shelter would include analysis equipment to enable the astronauts to decide which geologic samples should be returned to Earth (Bellcomm assumed that the astronauts would collect more samples than the LEM-Taxi could carry to lunar orbit, so some form of "discrimination" would be required). After 14 days on the Moon, they would abandon the LEM-Shelter, revive the LEM-Taxi, and return to the XCSM in lunar orbit in the LEM-Taxi ascent stage. Mission duration would total about 20 days.

Bellcomm noted that astronauts living in the LEM-Shelter for 14 days stood a 28% chance of exceeding their allowed mission radiation dose. Passing the limit would force them to terminate their surface mission early. Beefing up radiation protection would dramatically increase LEM-Shelter weight. They determined that, combined with other modifications required for months-long hibernation and a 14-day surface stay — for example, replacement of Apollo LEM batteries with fuel cells and insulated tanks containing cryogenic liquid oxygen/liquid hydrogen fuel cell reactants — the LEM-Shelter might put on so much weight that its landing legs would collapse (unless, of course, they were also modified).

SA-221 (May 1970) was a three-man, 30-to-45-day XCSM/LEM-Lab mission in near-equatorial low-Earth orbit dedicated to meteorology, agricultural remote sensing, and oceanography, placing it in the Earth-Oriented mission class. The Bellcomm engineers stressed that astronauts on board would serve as "trained observers" and "data filters," functions that automated satellites were unable to perform. The following month, SA-516 (XCSM/LEM Lab, 30-45 days, geosynchronous orbit) would test an astronomy payload.

SA-517 (August 1970), the second Lunar Orbital Survey mission, would see an XCSM/LEM-Lab/descent stage stack enter an orbit inclined steeply relative to the lunar equator, enabling it to pass over a larger portion of the lunar surface than its predecessor SA-511. SA-518 in October 1970, an XCSM/LEM-Lab, would survey the Earth from polar orbit using instruments tested during SA-215. SA-519 (December 1970) would round out the year by delivering a LEM-Shelter to a new complex landing site on the Moon.

The first mission of the AES program's last year would be the February 1971 SA-520 LEM-Taxi mission to the LEM-Shelter delivered during SA-519. Next up would be Earth-Oriented SA-521 (April 1971), which would see three astronauts in an XCSM/LEM-Lab study meteorology and oceanography from geosynchronous orbit for up to 45 days. Bellcomm noted that AES meteorological studies might lead to an "economical" weather satellite system or even "eventual control of the weather."

In June 1971, NASA would launch to lunar polar orbit SA-522 (XCSM/LEM-Lab/descent stage), the third and final AES Lunar Orbital Survey Mission. In polar orbit, the spacecraft would pass over the lunar polars on every orbit and fly over the entire lunar surface in daylight over a period of about a month.

SA-523 (XCSM/LEM-Lab) would be a long-duration Earth-orbital astronomy mission with a substantial biomedical/behavioral component (August 1971). SA-229 (XCSM/LEM-Lab) would rendezvous with and resupply SA-523 in September 1971.

SA-524 (October 1971) would deliver to the Moon the third and last LEM-Shelter of Bellcomm's AES FMAP. The same month, SA-230 (XCSM/LEM-Lab) would rendezvous with and resupply the ongoing SA-523 mission in Earth orbit. The final scheduled AES FMAP mission, SA-525 in December 1971, would see astronauts in a LEM-Taxi descend from an XCSM in lunar orbit to land near the SA-524 LEM-Shelter for 14 days of exploration.

The Bellcomm engineers argued that AES could accomplish many more types of missions if NASA's ground rules were relaxed. They suggested, for example, that another LEM derivative, the LEM-Truck, be developed to deliver large lunar surface payloads, such as more capable rovers, to the surface of the Moon in the period after 1971. The LEM-Truck would enable planners to abandon entirely the restrictive confines of the LEM ascent stage, permitting maximum exploitation of descent stage payload capacity. Grumman had studied the LEM-Truck since 1962.

The LEM-Truck was a LEM descent stage that included ascent stage systems required for landing on the Moon. Cargo would replace the LEM ascent stage. The image shows cargo volume available atop the LEM-Truck. Image credit: Grumman Aircraft Engineering Company.
In March 1965, against a backdrop of budget hearings in Congress, President Johnson made a surprise visit to NASA Headquarters. He received a briefing on Mariner IV, which had left Earth for Mars on 28 November 1964. Along with Vice President Hubert Humphrey's visit to Cape Kennedy a few days earlier, this was widely seen as a show of support for programs in the Fiscal Year 1966 NASA budget, including AES.

In August 1965, with the Fiscal Year 1966 budget in effect since 1 July, George Mueller established the Saturn/Apollo Applications Office at NASA Headquarters. The following month, AES became the Apollo Applications Program (AAP). The name changes signalled that NASA managers had learned an important lesson during the Fiscal Year 1966 budget cycle; that extending Apollo had less appeal than applying Apollo to new tasks with benefits for people on Earth.

Webb and Mueller remained outwardly enthusiastic about minimally modified Apollo spacecraft and long-duration missions; during August 1965 visits to the NASA Manned Spacecraft Center (MSC) in Houston, Texas, for example, Webb reiterated that AAP should use "off-the-shelf" spacecraft with minimal modifications. Mueller, for his part, raised the possibility of a 135-day XCSM/LEM-Lab AES Earth-orbital mission in a 27 August 1965 letter to MSC director Robert Gilruth.

Bellcomm, Grumman, and NASA in-house studies had, however, by August 1965 raised questions about the practicality of using modified Apollo spacecraft for long-duration flights. On 20 August 1965, NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama, home of the Saturn rocket family, began an in-depth in-house study of an orbital "workshop" based on the 21.7-foot-diameter S-IVB stage. The S-IVB was the second stage of the Saturn IB and the third stage of the Saturn V.

At the end of November, MSFC planners briefed Mueller on their results as part of the lead-up to NASA's Fiscal Year 1967 budget request. On 1 December 1965, Mueller gave MSFC director Wernher von Braun authority to establish the S-IVB Workshop Project Office.

Apollo and AES Flights in the January 1965 AES FMAP (includes Voyager)
  1. 1/66 - SA-201 - Apollo
  2. 4/66 - SA-202 - Apollo
  3. 7/66 - SA-203 - Apollo
  4. 10/66 - SA-204 - Apollo, CSM test
  5. 1/67 - SA-205 - Apollo, CSM/LEM test
  6. 1/67 - SA-501 - Apollo
  7. 4/67 - SA-206 - Apollo
  8. 5/67 - SA-502 - Apollo
  9. 7/67 - SA-207 - Apollo
  10. 10/67 - SA-503 - Apollo
  11. 11/67 - SA-208 - Apollo or AES, unassigned
  12. 2/68 - SA-504 - Apollo
  13. 3/68 - SA-209 - AES, Apollo CSM/Apollo LEM ascent stage
  14. 5/68 - SA-505 - Apollo
  15. 6/68 - SA-210 - Voyager, Saturn IB/Centaur
  16. 8/68 - SA-506 - Apollo, lunar landing 1
  17. 9/68 - SA-211 - AES, XCSM/LEM-Lab
  18. 11/68 - SA-507 - Apollo, lunar landing (SA-506 backup), or AES, Apollo CSM/Apollo LEM
  19. 12/68 - SA-212 - AES, unassigned
  20. 1/69 - SA-213 - Voyager, Saturn IB/Centaur
  21. 2/69 - SA-508 - Apollo, lunar landing 2
  22. 2/69 - SA-214 - Voyager, Saturn IB/Centaur
  23. 4/69 - SA-509 - AES, Apollo CSM/Apollo LEM ascent stage
  24. 5/69 - SA-215 - AES, Apollo CSM/Apollo LEM ascent stage
  25. 6/69 - SA-510 - Apollo, lunar landing 3
  26. 7/69 - SA-216 - AES, unassigned
  27. 8/69 - SA-511 - AES, XCSM/LEM-Lab/descent stage
  28. 9/69 - SA-217 - AES, unassigned
  29. 10/69 - SA-512 - Apollo, lunar landing 4
  30. 12/69 - SA-513 - AES, Apollo CSM/Apollo LEM ascent stage
  31. 12/69 - SA-218 - AES, XCSM/LEM-Lab
  32. 1/70 - SA-219 - AES, XCSM/LEM-Lab
  33. 2/70 - SA-514 - AES, Apollo CSM/LEM-Shelter
  34. 4/70 - SA-220 - AES, unassigned
  35. 4/70 - SA-515 - AES, XCSM/LEM-Taxi
  36. 5/70 - SA-221 - AES, XCSM/LEM-Lab
  37. 6/70 - SA-516 - AES, XCSM/LEM-Lab
  38. 7/70 - SA-222 - AES, unassigned
  39. 8/70 - SA-517 - AES, XCSM/LEM-Lab/descent stage
  40. 9/70 - SA-223 - AES, unassigned
  41. 10/70 - SA-518 - AES, XCSM/LEM-Lab
  42. 11/70 - SA-224 - AES, unassigned
  43. 12/70 - SA-519 - AES, Apollo CSM/LEM-Shelter
  44. 1/71 - SA-225 - AES, unassigned
  45. 2/71 - SA-520 - AES, XCSM/LEM-Taxi
  46. 3/71 - SA-226 - AES, unassigned
  47. 4/71 - SA-521 - AES, XCSM/LEM-Lab
  48. 5/71 - SA-227 - Voyager, Saturn IB-Centaur
  49. 6/71 - SA-228 - Voyager, Saturn IB-Centaur
  50. 6/71 - SA-522 - AES, XCSM/LEM-Lab/descent stage
  51. 8/71 - SA-523 - AES, XCSM/LEM-Lab
  52. 9/71 - SA-229 - AES, XCSM/LEM-Lab
  53. 10/71 - SA-524 - AES, Apollo CSM/LEM-Shelter
  54. 10/71 - SA-230 - AES, XCSM/LEM-Lab
  55. 12/71 - SA-525 - AES, XCSM/LEM-Taxi
Sources

Final Technical Presentation: Modified Apollo Logistics Spacecraft, Contract NAS 9-1506, North American Aviation, Inc., Space and Information Systems Division, November 1963.

Study of LEM for Lunar Orbital Reconnaissance, ASR 323D-1, Grumman Aircraft Engineering Company, 23 September 1963.


"LBJ Wants Post-Apollo Plans," H. Taylor, Missiles and Rockets, 4 May 1964, p. 12.

"Interim Report for AES Flight Mission Assignment Plan — Part I: Summary," Bellcomm TM-65-1011-7, T. Powers, 29 January 1965.

"Interim Report for AES Flight Mission Assignment Plan — Part III: Extended CSM Spacecraft," Bellcomm TM-65-1011-2, K. Martersteck, 29 January 1965.

"Interim Report for AES Flight Mission Assignment Plan — Part IV: LEM Derivatives," Bellcomm TM-65-1011-3, J. Waldo, 29 January 1965.

"Interim Report for AES Flight Mission Assignment Plan — Part VII: Scheduling Constraints and Alternative Schedules," Bellcomm TM-65-1011-6, P. Gunther, 29 January 1965.

"Top-Level Space Support," W. Coughlin, Missiles and Rockets, 8 March 1965, p. 46.

"NASA to Decide Key AES Issues in June," W. Normyle, Aviation Week & Space Technology, 24 May 1965, pp. 16-17.

LEM Utilization Study for Apollo Extension System Missions, Final Report - Volume I: Summary, Design 378, Grumman Aircraft Engineering Company, 15 October 1965.

Skylab: A Chronology, R. Newkirk and Ivan Ertel with Courtney Brooks, NASA, 1977, pp. pp. 28-29, 35-43, 47-55.

More Information

Space Station Resupply: The 1963 Plan to Turn the Apollo Spacecraft into a Space Freighter

The First Voyager (1967)

Riccioli Outpost (1990)

The red oval at left marks Riccioli crater, Paul Lowman's candidate site for a lunar geology/astronomy outpost. The crater is approximately round, but appears foreshortened because it is near the lunar limb. Image credit: NASA.
NASA held a workshop in August 1990 to examine candidate lunar base sites as part of the Space Exploration Initiative (SEI). U.S. President George H. W. Bush had announced SEI on 20 July 1989, the 20th anniversary of the Apollo 11 Moon landing. SEI aimed to return American astronauts to the Moon to stay and to carry out the first piloted Mars expedition. For most of its first year, SEI lacked a timetable, though in November 1989, The 90-Day Study, NASA's initial SEI blueprint, scheduled the return to the Moon for as early as 2001. On 11 May 1990, Bush called for American astronauts on Mars by 2019.

One candidate lunar base site was 156-kilometer-wide Riccioli crater. Riccioli is located southwest of Oceanus Procellarum, near the edge of the Moon's disk as viewed from Earth, just west of prominent dark-floored Grimaldi basin. Named by 17th-century astronomer-priest Giovanni Battista Riccioli for himself, the crater includes slumped crust blocks (graben) overlain with ejecta from the impact that blasted out the nearby multi-ringed Orientale basin, the youngest large basin on the Moon.

Heavily degraded Riccioli crater. The red oval marks a possible outpost site on the interior uplift. Light-colored ejecta from Mare Orientale (out of shot to the lower left) is discernible over much of the crater. Image credit: NASA.
Riccioli's ancient, complex geology and its position near the Moon's equator and western limb had drawn the gaze of geologist Paul Lowman. At the August 1990 workshop, he advocated for the crater's irregular interior uplift as the site for a geoscience outpost and astronomical observatory. In places, the interior uplift stands more than 800 meters above the crater floor.

Paul Lowman. Image credit: NASA
NASA put Lowman on its payroll in 1959. By some accounts, he was the agency's first geologist. He worked at NASA Headquarters in Washington, DC, then moved to the newly built NASA Goddard Space Flight Center in Greenbelt, Maryland, a Washington suburb. He trained Mercury, Gemini, and Apollo astronauts to identify and photograph Earth's geologic features from Earth orbit and participated in the development of Apollo lunar geology experiments. He wrote about future lunar mining as a member of the interagency Working Group on Extraterrestrial Resources; he also took part in an internal NASA study of a temporary lunar outpost based on Lunar Module spacecraft and other Apollo technology (please see "More Information" below).

After Apollo, Lowman participated in Skylab Earth observation experiments and the Landsat Program. The Earth-orbiting Landsat automated satellites sought resources and monitored the environment on Earth.

Lowman assumed that geologist-astronauts at Riccioli outpost would have at their disposal several rovers equipped as campers. He planned three traverses within Riccioli, each about 100 kilometers long with multiple stops. The traverses would each last several days.

Traverse 1 would begin with a sample stop just outside the outpost's front door. Lowman believed that the Riccioli interior uplift might include some of the oldest lunar crust. From there, the geologist-astronauts would drive across the dark mare to sample light plains material — probable ejecta from the Orientale basin — on Riccioli's northeast rim. The Orientale ejecta, he asserted, could contain pieces of mantle material from deep within the Moon.

Lowman's Traverse 2 would explore criss-cross grabens and rilles (canyons) in search of recent volcanism. Lowman hoped that the explorers might uncover water-rich minerals they could mine.

During Traverse 3, they would sample craters with dark haloes along the Riccioli southeast rim about 50 kilometers from the outpost. Lowman believed that the dark haloes could be signs of relatively recent volcanism; that the craters they surround could be volcanic vents and the haloes erupted volcanic material. Alternately, the impacts that blasted out the craters might have exposed ancient dark deposits buried beneath Orientale basin ejecta.

Lowman expected that geologist-astronauts would build on the exploration experience they gained in Riccioli crater to rove beyond its degraded walls. Riccioli is located in the Moon's "wild west," a region of complex geology that even today is in many ways mysterious. Lowman named as geologic exploration targets within a few hundred kilometers of Riccioli the ring mountains and small mare plains of Mare Orientale; the Reiner Gamma swirls, a prominent magnetic anomaly; the Marius Hills volcanic complex, a highly ranked Apollo candidate landing site; and bright Aristarchus crater.

Astronomers based at near-equatorial Riccioli outpost could, Lowman added, observe nearly the entire celestial sphere every month. He suggested that the generally level Riccioli crater floor could provide a stable platform for groups of sensitive astronomical instruments that needed to be kept carefully aligned to function properly. A cluster of carefully aligned small telescopes could, he noted, act as a single large telescope.

Riccioli crater's near-limb location meant that Earth would stand low in the eastern sky; low enough that at some locations the crater rim and central uplift could hide the home planet from view. Radio telescopes built out of sight of Earth could, he explained, operate without interference from terrestrial artificial and natural radio sources.

Lowman revealed a playful side when he proposed that Riccioli outpost might include a bright strobe light. This could be activated when the Moon was at first-quarter phase, when it stands high and half-lit immediately after sunset for observers on Earth. The Sun would not yet have risen at Riccioli crater, so the blinking strobe would stand out against the dark part of the first-quarter lunar disk.

SEI excited many space scientists, engineers, and enthusiasts, though neither the public nor the Congress supported it. The U.S. economy fell into recession in 1990; set against a backdrop of economic hardship, the Moon and Mars program appeared frivolous. SEI ended soon after President Bush left the Oval Office in January 1993. NASA, meanwhile, redoubled its efforts toward building the International Space Station in low-Earth orbit in cooperation with its long-time International Partners Europe, Canada, and Japan and with its old rival Russia.

Lowman, for his part, never stopped advocating for a lunar outpost, and Riccioli crater remained his favorite candidate outpost site. In 1996, taking into account new miniaturized space technology and capable robots, he proposed a mostly automated astronomy outpost in Riccioli crater built up using small, cheap automated landers. Lowman passed away a week after his 80th birthday on 29 September 2011.

Sources

A Site Selection Strategy for a Lunar Outpost — Science and Operational Parameters: Determining the Impact of Science and Operational Parameters for Six Sites on the Moon by Simulating the Selection Process, Conclusions of a Workshop, 13-14 August 1990, Solar System Exploration Division, NASA Johnson Space Center, Houston, Texas, pp. 31-36.

"Remembering Paul Lowman," Landsat Science (https://landsat.gsfc.nasa.gov/remembering-paul-lowman/ — accessed 30 December 2019).

"Paul Lowman: NASA's 76-Year-Old Maverick," NASA Goddard Space Flight Center, 11 September 2007 (https://www.nasa.gov/centers/goddard/news/series/moon/lowman_intro.html — accessed 30 December 2019).

More Information

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Harold Urey and the Moon (1961)

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