The year 1984 was nearly equidistant between the first moon landing of 1969 and the evocative year 2001. The Shuttle, flown first on 12 April 1981, had been declared operational by President Ronald Reagan, who, in his January 1984 State of the Union Address, had also given NASA leave to build its long-sought-after low-Earth-orbit (LEO) Space Station. Space supporters could be forgiven for believing that, after the gap in U.S. human space missions spanning from July 1975 to April 1981, a new day was dawning; that Shuttle and Station would lead in the 1990s to piloted flights beyond LEO. Surely, Americans would once again walk on the moon by 2001, and would put bootprints on Mars not long after.

There were, of course, some problems: despite being declared operational, Shuttle operations had yet to become routine. Despite some high-flung rhetoric at the time it was announced - President Reagan had talked of following "our dreams to distant stars" - the Station he agreed to fund was meant to serve as a laboratory, not a jumping-off place for missions beyond LEO. Hardware for any "space port" function it might eventually fulfill would need to be bolted on later, after some future President gave the word. In addition, NASA's robotic exploration program remained a shadow of its former self. There would, for example, be no U.S. robotic probe in the international armada to Halley's Comet in 1985-1986.

Nevertheless, with American astronauts in space again and concept artists hard at work on tantalizing visions of sprawling space stations, very few foresaw rough waters ahead. It seemed the perfect time to revive advanced planning for missions to the moon and beyond, which had been virtually moribund in the U.S. since the early 1970s.

Advanced planning revived first outside of NASA. Participants in the 1981 and 1984 Case for Mars conferences, mindful of how Apollo had left no long-term foothold on the moon, developed a plan for a permanent Mars base. The Planetary Society, with 120,000 members the largest spaceflight advocacy group on Earth, helped to pay for the Case for Mars conferences. The Planetary Society had grown rapidly following its founding in 1980 in large part because its President was planetary scientist Carl Sagan. His 1980 PBS television series Cosmos had done more to popularize spaceflight than any public outreach effort since Wernher von Braun's 1950s collaborations with Walt Disney and Collier's magazine.

In 1984, The Planetary Society paid the Space Science Department of Science Applications International Corporation (SAIC) in suburban Chicago, Illinois, to outline three piloted space projects for the first decade of the 21st century. These were: an expedition to scout out a site for a permanent lunar base; a two-year journey to 1982DB, in 1984 the most easily accessible Earth-approaching asteroid known (it remains one of the most accessible, but is now called 4660 Nereus); and, most ambitious, a three-year mission to land three astronauts on Mars for 30 days.

The projects were not meant to occur in order; in fact, any one of them could stand alone. In its report to The Planetary Society, the six-man SAIC study team declared that "any. . .would be a commanding goal for future U.S. space exploration."

The Planetary Society favored space missions of an international character; it saw in them a means of reducing geopolitical tension on Earth and of dividing the cost of exploration among the space-faring nations. In his Foreword to the SAIC report, Carl Sagan wrote of his hope that the study would "stimulate renewed interest in major international initiatives for the exploration of nearby worlds in space." The SAIC team did not, however, emphasize this; apart from the European Space Agency-provided Spacelab modules upon which the pressurized modules of its spacecraft would be based, there was little evidence of international involvement in its proposed missions.

The SAIC planners assumed that NASA would convert the Space Station into an LEO spaceport at the turn of the 21st century. The U.S. civilian space agency would use its Shuttle fleet to launch to the Station hangars, living accommodations for crews in transit to destinations beyond LEO, remote manipulators, propellant storage tanks, and auxiliary spacecraft such as Orbital Transfer Vehicles (OTVs). Parts and propellants for the team's piloted moon, asteroid, and Mars spaceships would also reach the Station on board Shuttle Orbiters.

The SAIC team wrote that it had assumed no Space Shuttle upgrades. The standard Shuttle Orbiter had a 15-by-60-foot (4.6-by-18.5-meter) payload bay and could in theory carry up to 60,000 pounds (27,270 kilograms) of cargo into LEO. Curiously, however, the team estimated the number of Shuttle flights needed to launch parts and propellants for its lunar and asteroid missions based on the assumption that the Shuttle could transport 65,000 pounds (29,545 kilograms) to LEO. Only its Mars mission assumed use of the standard "60K" Shuttle.

Image: SAIC

SAIC's lunar base site survey mission closely resembled one it had presented in its December 1983 report to the National Science Foundation. The mission - for which SAIC gave no starting date - would need a total of 12 Shuttle launches and four manned and unmanned "sorties" to the moon.

SAIC planners assumed that the Station would normally include in its fleet of auxiliary vehicles two reusable OTVs, each with a fully fueled mass of about 70,400 pounds (32,000 kilograms). These would suffice for the company's lunar project, but more OTVs - including some expendable ones - would be needed for its asteroid and Mars missions.

At the start of each lunar mission, a "stack" comprising a lunar payload, OTV #2, and OTV #1 would move away from the Station. OTV #1 would fire its twin RL-10-derived engines at perigee (the low point in its Earth-centered orbit) to push OTV #2 and a lunar payload out of LEO into an elliptical orbit. OTV #1 would then separate and fire its engines at next perigee to lower its apogee (the high point in its Earth orbit), recircularizing its orbit so that it could return to the Space Station for refurbishment and refueling. OTV #1 would burn 59,870 pounds (27,215 kilograms) of propellants.

OTV #2 would fire its engines at next perigee to place the lunar payload on course for the moon. Depending on the nature of the payload, OTV #2 would then either fire its engines to slow down and allow the moon's gravity to capture it into lunar orbit or would separate from the lunar payload and adjust its course so that it would swing around the moon and fall back to Earth.

The SAIC team envisioned that OTV #2 would be fitted with a reusable aerobrake heat shield. After returning from the moon, it would skim through Earth's upper atmosphere to shed speed, then would adjust its attitude relative to its center of mass using small thrusters so that it would gain lift and skip up out of the atmosphere. At apogee, it would fire its twin engines briefly to raise its orbit's perigee out of the atmosphere. OTV #2 would then rendezvous with the Station, where it would be refurbished and refueled for a new mission.

The SAIC team's lunar project would begin with unmanned Sortie #1. A pair of nearly identical 15,830-pound (7195-kilogram) pressurized rover-trailer combinations would reach the moon on a one-way lander. OTV #2 would swing around the moon after releasing the lander and rover-trailers, which would descend directly to a soft landing in the proposed lunar base region.

For Sortie #2, OTV #2 would enter a 30-mile-high (50-kilometer-high) lunar orbit and release an unmanned, unfueled single-stage Lunar Excursion Module (LEM) lander. OTV #2 would then fire its twin engines to depart lunar orbit. After aerobraking in Earth's atmosphere, it would return to the Station.

Image: SAIC

The first manned sortie, Sortie #3, would see OTV #2 deliver to lunar orbit four astronauts in a pressurized crew module. They would pilot the OTV #2/crew module combination to a docking with the waiting LEM. The crew would board the LEM, load it with propellants from OTV #2, then undock. OTV #2 would fire its engines to depart lunar orbit, then would fall back to Earth, aerobrake on the atmosphere, and return to the Station.

The astronauts, meanwhile, would descend in the LEM to a landing near the one-way lander and twin rover-trailers. They would divide up two per rover-trailer and commence a 30-day survey of candidate base sites within the 30-mile-wide (50-kilometer-wide) proposed lunar base region. In addition to providing living quarters, the rover-trailers would each carry 2640 pounds (1200 kilograms) of science instruments for determining surface composition, seismicity, and stratigraphy at candidate base sites, plus a scoop or blade for moving large quantities of lunar dirt. They would rely on liquid oxygen-liquid methane fuel cells for electricity to power their drive motors.

The rover-trailers would travel together for safety; if one broke down and could not be repaired, the other could return all four astronauts to the waiting LEM. Travel in harsh sunlight would be avoided. SAIC assumed that the rover-trailer combinations would spend most of the two-week lunar day parked at a "base camp" under reflective thermal shields, from which they would venture out for only a few 24-hour excursions. They would travel continuously during the two-week lunar night, however, their way lit by headlights and earthlight.

Sortie #4 would see OTV #2 and the crew module return unmanned to lunar orbit. The crew, meanwhile, would park the rover-trailers under the base camp thermal shields, load the LEM with samples, photographic film, and other data from their rover-trailer traverses, and ascend in the LEM to lunar orbit to rendezvous and dock with the OTV #2/crew module combination. They would then undock from the LEM, depart lunar orbit, aerobrake in Earth's atmosphere, and rendezvous with the Station. The SAIC planners proposed that the orbiting LEM and parked rover-trailers be put to work again during the initial phase of lunar base buildup.

For its second early 21st-century manned space project, SAIC considered eight mission plans and four asteroid targets (three of which were hypothetical, reflecting the fact that new potential targets were being found all of the time). It settled on a two-year voyage that would include a wide swing out into the Main Belt of asteroids between Mars and Jupiter. There the spacecraft would fly past asteroid 1577 Reiss. The main target of the mission would, however, be the Earth-approaching asteroid 1982DB. Nine upgraded ("65K") Shuttle Orbiters would launch parts and propellants for the spacecraft and the OTVs necessary to launch it from Earth orbit.

Following assembly and checkout, the manned asteroid mission spacecraft/OTV stack would move away from the Station. A total of five OTVs would be needed to launch the asteroid mission spacecraft out of Earth orbit. OTV #1 would ignite at the stack's perigee to raise its apogee. It would then separate and fire its engines at next perigee to lower its apogee, recircularizing its orbit so it could return to the Station. OTV #2 would ignite at next perigee to boost the stack's apogee higher, then would detach and aerobrake in Earth's atmosphere to return to the Station. OTV #3 and OTV #4 would do the same.

The time between perigees would increase with each burn: the five-burn sequence would need about 48 hours, with nearly 24 hours separating the OTV #4 and OTV #5 perigee burns. On 5 January 2000, OTV #5 would fire its engines at perigee until it exhausted its propellants, launching SAIC's asteroid mission spacecraft out of Earth orbit and onto a Sun-centered path toward 1577 Reiss and 1982DB. OTV #5 would then be discarded.

Image: SAIC/David S. F. Portree

The crew would next spin up their spacecraft. Twin 81.25-foot-long (25-meter-long) hollow arms, each carrying a solar array and a radiator panel, would link twin habitat modules to a cylindrical central hub. Habitats, booms, and hub would spin three times per minute to create acceleration in the habitats, which the crew would feel as a continuous pull of 0.25 Earth gravities.

SAIC lacked data on whether 0.25 gravities would be sufficient to mitigate the deleterious effects of weightlessness (indeed, such data do not exist at this writing). The team explained that its choice of 0.25 gravities constituted "a compromise between the desire to have a near normal gravity, a short habitat arm length, and a slow spin rate."

A logistics supply module and two propulsion systems would link to the central hub's aft end. The main propulsion system, which would burn liquid methane and liquid oxygen, would be used for course corrections during the long trip from Earth to 1982DB and for departure from 1982DB. The storable-bipropellant secondary system would perform 1982DB station-keeping maneuvers and course corrections during the short trip from 1982DB to Earth.

The hub's front would have linked to it an experiment module with a 16.25-foot (five-meter) radio dish antenna for high-data-rate communications, an "EVA station" for spacewalks, and a conical Earth-return capsule with a 37.4-foot (11.5-meter) flattened cone ("coolie hat") aerobrake. The modules on either end of the hub would spin as a unit in the direction opposite the hub, arms, and habitats, so would appear to remain motionless. Astronauts inside them would experience weightlessness.

Image: SAIC

The crew would point the Earth-return vehicle's aerobrake and the asteroid spacecraft's twin solar arrays toward the Sun, placing radiators, propulsion systems, logistics module, hub, hollow arms, experiment module, EVA station, and Earth-return capsule in protective shadow. In the event of a solar flare, the crew would use the spacecraft's structure as radiation shielding: they would retreat to the logistics module, placing aerobrake, Earth-return capsule, EVA station, experiment module, hub, and logistics module structure and contents between themselves and the erupting Sun.

During their two-year mission, the crew would spend about 23 months doing "cruise science." Four hundred and forty pounds (200 kilograms) of the asteroid mission spacecraft's 1650-pound (750-kilogram) cruise science payload would be devoted to studies of human physiology in space, and 375 pounds (170 kilograms) would be used to perform solar observations and other astronomy and astrophysics studies. In addition, the spacecraft would carry 55 pounds (25 kilograms) of long-duration exposure samples on its exterior. These swatches of spacecraft metals, foils, paints, ceramics, plastics, fabrics, and glasses would be retrieved by spacewalking astronauts before the end of the mission.

SAIC's asteroid mission spacecraft would fly past 1577 Reiss at a speed of 2.8 miles (4.7 kilometers) per second on 2 March 2001, 14 months into the mission, and would intercept 1982DB six months after that, on 12 September 2001. It would spend 30 days near 1982DB, during which period Earth would range from 55 million miles (90 million kilometers) distant on 12 September to 30 million miles (50 million kilometers) away on 12 October.

While close to 1577 Reiss, the crew would use the "asteroid science" equipment packed in their spacecraft's experiment module for the first time. They would bring to bear on the asteroid a 220-pound (100-kilogram) package of remote-sensing instruments, including a mapping radar and instruments for determining surface composition. They would also image 1577 Reiss using high-resolution cameras with a total mass of 110 pounds (50 kilograms).

These instruments would again be put to use as the spacecraft closed on 1982DB. During approach, the crew would locate the 1600-foot-wide (500-meter-wide) asteroid precisely in space, determine its spin axis and spin rate, and perform long-range mapping. They would then halt a few hundred miles/kilometers from 1982DB to perform detailed global mapping. This would enable selection of sites for in-depth investigations.

The astronauts would move their spacecraft closer to 1982DB, halting a few tens of miles/kilometers away to commence in-depth exploration. They would then move their spacecraft even closer, to within a few miles/kilometers of the asteroid, at least 10 times (that is, every three days). During these close approaches, two astronauts would each don a Manned Maneuvering Unit (MMU) in the EVA station module, then would depart the asteroid spacecraft to land at a site of interest on 1982DB. They would spend up to four hours away from their spacecraft each time. After the crew returned from the surface, the spacecraft would resume its position several tens of miles away from 1982DB.

Mission to asteroid 1982DB. Image: Michael Carroll/

The astronauts would deploy four small and three large experiment packages on 1982DB and collect a total of 330 pounds (150 kilograms) of samples. The 110-pound (50-kilogram) small experiment packages would each include a seismometer and instruments for measuring temperature and determining surface composition. The 220-pound (100-kilogram) large packages would include a "deep core drill," a sensor package for insertion into the core hole, and a mortar. After the surface crew returned to the safety of the spacecraft, they would fire the mortars to send shockwaves through 1982DB. The small-package seismometers would register the shockwaves, enabling scientists to chart the asteroid's interior structure.

The SAIC team noted that 1982DB would have "negligible gravitational attraction," so the asteroid mission spacecraft would be unable to orbit it in a conventional sense. Spacecraft and asteroid would instead share nearly the same orbit around the Sun. 1982DB would, meanwhile, rotate at some unknown rate. The asteroid's rotation would mean that astronauts at a site of interest on its surface would tend to be carried away from their spacecraft. In fact, if 1982DB rotated quickly enough, astronauts on its surface might pass out of sight of the spacecraft during their four-hour "asteroid-walks."

The SAIC planners judged that loss of radio and visual contact between spacecraft and surface crew would be undesirable, so they proposed that the shipboard astronaut perform station-keeping maneuvers to match 1982DB's rotation; that is, that the astronaut keep his or her shipmates in sight by maintaining a "forced circular orbit" around 1982DB. The team budgeted enough storable propellants for a station-keeping velocity change of 32.5 feet (10 meters) per second per surface visit.

If 1982DB were found to rotate slowly, then the velocity change needed to maintain the spacecraft in its forced orbit would be reduced. In that case, the only limitations on the number of surface visits would be astronaut stamina, the supply of gaseous nitrogen MMU propellant, and the mission's planned 30-day stay-time near the asteroid.

On 12 October 2001, the crew would depart 1982DB and bend their trajectory so that it would almost intersect Earth. Three months later, they would load their samples, film, and other data into the conical Earth-return capsule and undock. On 13 January 2002, almost exactly two years after Earth departure, the crew would aerobrake their capsule in Earth's atmosphere and pilot it to a rendezvous with the Space Station. Meanwhile, the abandoned asteroid mission spacecraft would swing by Earth and enter orbit around the Sun.

Image: SAIC

SAIC's third proposed project, the first piloted Mars landing, would employ a single crew of four astronauts and two separate spacecraft. The largest spacecraft, the tripartite Mars Outbound Vehicle (MOV), would comprise the Interplanetary Vehicle, the Mars Orbiter, and the conical Mars Lander. The Mars Orbiter and Mars Lander together would comprise the Mars Exploration Vehicle.

The Interplanetary Vehicle would resemble the SAIC team's asteroid mission spacecraft, though it would lack an Earth-return capsule and would move through space with its logistics module pointed toward the Sun. The Interplanetary Vehicle's hub, twin hollow arms, and twin habitats would revolve independently of the rest of the MOV at a rate of three times per minute. Its EVA station would link it to the Mars Orbiter, a bare-bones, non-rotating vehicle made up of a single habitat module and hollow arm, a solar array, a radiator, a radio dish antenna, an EVA station, an unspecified propulsion system, and the conical Mars Departure Vehicle (MDV). The Mars Orbiter EVA station would link it to the Mars Lander ascent stage. The lander would include a 175.5-foot-diameter (54-meter-diameter) flattened-cone aerobrake.

SAIC's second, smaller Mars mission spacecraft, the Earth Return Vehicle (ERV), would resemble the asteroid mission spacecraft even more than would the Interplanetary Vehicle. It would, like the asteroid spacecraft, move through space with its Earth-return aerobrake pointed toward the Sun.

The unmanned ERV would depart Earth ahead of the MOV, on 5 June 2003, but would follow a path that would cause it to reach Mars after the MOV, on 23 January 2004. A total of five Shuttle Orbiters would launch ERV and OTV parts and propellants to the Station, then three OTVs (the two based at the Station plus one assembled at the Station specifically for the Mars mission) would launch the ERV toward Mars.

Each OTV would ignite its engines at perigee to increase the ERV/OTV stack's apogee. OTV #1 would use its engines to return to the Station after separating from the ERV/OTV #3/OTV #2 stack. OTV #2 would rely on its aerobrake heat shield to return to the Station. OTV #3 would expend all of its propellants to place the 94,600-pound (43,000-kilogram) ERV on course for Mars, then would be discarded. The three-orbit ERV Earth-orbit departure sequence would last about six hours.

The MOV with four astronauts on board would leave Earth orbit 10 days later, on 15 June 2003. Thirteen Space Shuttle launches would place MOV and OTV parts and propellants into Earth orbit. A total of seven OTVs would perform perigee burns over the space of a little more than two days to boost the 265,300-pound (120,600-kilogram) MOV toward Mars. Following separation, OTV #1 would ignite its engines at perigee to return to the Station; OTVs #2 through #6 would return to the Station after aerobraking; and OTV #7 would exhaust its propellants and be discarded.

The MOV would follow a slightly faster Earth-Mars trajectory than would the ERV, so would arrive at Mars on 24 December 2003, 30 days ahead of the ERV. Assuming that telemetry from the unmanned ERV showed that it remained able to support a crew, the MOV astronauts would cast off the Interplanetary Vehicle (top image above), strap into the Mars Lander ascent capsule, and aerobrake in Mars's atmosphere. The abandoned Interplanetary Vehicle, meanwhile, would swing past Mars and enter solar orbit.

Following aerobraking, the two-part Mars Exploration Vehicle would climb to an apoapsis (orbit high point) of 600 miles (1000 kilometers). Once there, the Mars Orbiter and Mars Lander would separate. One astronaut would remain on board the Mars Orbiter. He or she would ignite the Mars Orbiter's propulsion system at apoapsis to raise its periapsis (orbit low point) to 600 miles (1000 kilometers), giving it a circular orbit about Mars. The three astronauts in the Mars Lander, meanwhile, would fire its engine briefly at apoapsis to raise its periapsis to an altitude just above Mars's atmosphere.

As the planet rotated beneath the Mars Lander, the three astronauts would prepare for atmosphere entry and landing. As the target Mars landing site came into view, they would ignite the Mars Lander's engine at apoapsis, lowering their periapsis into the atmosphere. They would cast off the aerobrake after atmosphere entry and lower to a soft landing using the Mars Lander descent engine.

Immediately after touchdown, the crew would deploy a teleoperated rover. Trailing power cables, the rover would carry a small nuclear reactor to a point a safe distance away from the Mars Lander and bury it. The crew would then remotely activate the reactor to supply their encampment with electricity.

SAIC's Mars mission would, of course, have a range of cruise, Mars orbital, and Mars surface science objectives. The study team explained that, during the six-month Earth-Mars cruise, the astronauts would have at their disposal on board the Interplanetary Vehicle a cruise science payload identical to that on the asteroid mission spacecraft. Human physiology studies during Earth-Mars cruise would focus on keeping the Mars landing crew in good shape for a strenuous 30 days on the planet. The astronauts would also observe the Sun.

At Mars, they would perform Mars Orbiter and Mars Lander science. The "primary duty" of the lone astronaut on board the Mars Orbiter would be to support the surface team, the SAIC planners explained. Four hundred and forty pounds (200 kilograms) of remote sensors would enable him or her to spot threatening weather conditions near the landing site and to generate detailed maps of landing site terrain and surface composition for the surface crew and for scientists and mission planners on Earth.

The surface astronauts would have as "a major goal" the selection of a future Mars base site, the SAIC team explained. They would have at their disposal 1980 pounds (900 kilograms) of science equipment, including a 220-pound (100-kilogram) Mobile Geophysics Lab rover, 110 pounds (50 kilograms) of high-resolution cameras, four small deployable science packages with a mass of 110 pounds (50 kilograms) each, and three large deployable science packages with a total mass of 880 pounds (400 kilograms) each.

The small packages would measure temperature, Mars quakes, and surface composition, while the large packages would include a 440-pound (200-kilogram) deep-core drill, a 220-pound (100-kilogram) sensor package for insertion down core holes, and a mortar for generating shock waves that the seimometers in the small packages would register, permitting scientists on Earth to understand the landing site's subsurface structure. The surface crew would also set up an inflatable "tent" in which they would begin examination of the 550 pounds (250 kilograms) of Mars samples they would collect for return to Earth.

Image: SAIC

As the ERV approached Mars, the surface crew would transfer their samples, film, and other data to the Mars Lander ascent stage and blast off to rendezvous with the Mars Orbiter. The nuclear reactor they left behind might power equipment long after they departed. The SAIC team suggested that it drive a system that would extract oxygen from Mars's atmosphere and cache it for future Mars base builders.

After docking with the Mars Orbiter, the four astronauts would transfer their surface and orbital Mars data to the MDV, then would undock from the Mars Orbiter in the MDV and set out in earnest pursuit of their ride home. Because launching it back onto an interplanetary path after crew recovery in Mars orbit would demand considerable quantities of propellants, the ERV would not enter Mars orbit. Instead, to reduce overall Mars mission mass (and thus the number of Shuttle launches needed to launch it into LEO and and the number of OTVs needed to place it on course for Mars), the crew would rendezvous with the ERV as it raced past the planet on a free-return trajectory that would take it back to Earth after 1.5 orbits around the Sun and 2.5 years of flight time. This approach, which SAIC termed Mars Hyperbolic Rendezvous (MHR), resembled the Flyby Landing Excursion Mode put forward by Republic Aviation engineer R. Titus in 1966 (though they did not reference his pioneering work).

As might be expected, the SAIC team felt it necessary to study possible contingency modes for crew recovery in the event that MHR failed. If, for example, the unmanned ERV malfunctioned en route to Mars before the crew discarded the Interplanetary Vehicle and aerobraked the Mars Exploration Vehicle into Mars orbit, the astronauts could perform a powered Mars swingby maneuver using the Mars Lander and Mars Orbiter propulsion syetms, bending their course so that they would intercept Earth 2.5 years later. The crew would separate in the Mars Lander near Earth and use its aerobrake to capture into Earth orbit.

Assuming, however, that all went as planned, the MDV would dock with the ERV a few hours after leaving Mars orbit. As Mars shrank behind them, the astronauts would transfer to the ERV with their samples and data, cast off the spent MDV, and spin the ERV's hub, arms, and habitats to create acceleration.

During the 2.5-year cruise home to Earth, the astronauts would use a science payload identical to that carried on board the Interplanetary Vehicle and the asteroid mission spacecraft to study human physiology during long-term spaceflight, the Sun, and astrophysics. The SAIC planners suggested that they might also continue study of the samples they had collected on Mars, though they did not indicate how this would be accomplished in the absence of an isolation lab and the necessary instruments and tools.

On 5 June 2006, three years to the day after they left Earth, the crew would undock in the 9750-pound (4430-kilogram) Earth-return capsule, aerobrake in Earth's atmosphere, and rendezvous with the Space Station. The abandoned ERV, meanwhile, would swing past Earth and enter solar orbit.

SAIC offered preliminary cost estimates for its three projects and compared them with the cost of the Apollo Program, which encompassed 11 manned missions, six of which landed two-man crews on the moon. A dispassionate observer might be forgiven for seeing the team's cost estimates as unrealistically low. Partly this was the result of Shuttle cost-accounting. Taking its lead from NASA, the SAIC team calculated that the 18 Shuttle flights needed for its Mars mission would cost only $2 billion, or about $110 million per flight.

The lunar base site survey would, the SAIC planners calculated, cost only $16.5 billion, or about a quarter of the Apollo Program's $75-billion cost in 1984 dollars. The asteroid mission would be slightly cheaper, coming in at $16.3 billion. The Mars mission, not surprisingly, would be the most costly of the three. Even so, it would only cost about half as much as Apollo; SAIC gave it a pricetag of just $38.5 billion.

Less than two years after SAIC turned over its study to The Planetary Society, the optimistic era of piloted mission planning that had begun with the launch of the first Space Shuttle drew to a close. Following the loss of the Shuttle Orbiter Challenger on 28 January 1986, at the start of the 25th Shuttle mission, advance planning did not stop; in fact, it expanded as part of efforts to demonstrate that NASA's Shuttle and Station Programs had worthwhile long-term objectives, and thus should continue in spite of Challenger.

The rules, however, had changed. After Challenger, few planners assumed that the Space Station President Reagan had called for in January 1984 would ever become an LEO spaceport, and even fewer assumed that Shuttle Orbiters alone would suffice to launch the components and propellants needed for piloted missions beyond LEO. Post-Challenger plans would call for a purpose-built LEO spaceport to augment the Station and Shuttle-derived heavy-lift rockets to augment the Shuttle. Both of these would increase the estimated cost of piloted exploration beyond LEO.

Thanks to artist/writer Michael Carroll () for providing the color images that illustrate this post.

References:

Manned Lunar, Asteroid, and Mars Missions - Visions of Space Flight: Circa 2001, A Conceptual Study of Manned Mission Initiatives, Space Sciences Department, Science Applications International Corporation, September 1984.

"Visions of 2010 - Human Missions to Mars, the Moon and the Asteroids, Louis D. Friedman, The Planetary Report, March/April 1985, pp. 4-6, 22.

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