Mars Expeditions Credit - © Mark Wade

Work resumed in the 1980's, led in America by private advocacy groups, and in the Soviet Union by Glushko, who saw the new Energia heavy-lift booster as the means of reaching Mars. In the late 1980's there was even a brief 'Race to Mars', with both sides putting forward designs. This unexpected revival of the space race ended with the collapse of the Soviet Union and the scrapping of the Energia booster. Despite press enthusiasm, such a project never had any high-level political support in either country.

Despite pronouncements by a succession of American presidents that a manned expedition to Mars was a long-term national goal, there has never been the political will to provide the funding necessary for such an enterprise. By 2005 NASA had funded a dizzying array of studies and iterations, all basically trading launch mass from low earth orbit for time and risk of mission failure. No compelling concept emerged. The safest way would be for an expedition to Mars being the result of a robust space infrastructure (heavy lift boosters, aerobraking space tugs, nuclear thermal engines, long-term cryogenic propellant storage) already developed and in place. But there was no prospect of such an infrastructure being funded...

	Von Braun Mars Expedition - 1952	Wernher von Braun made the first engineering analysis of a manned mission to Mars in 1948. He published his calculations in 1952, and they subsequently reached a wide audience in Collier's magazine, a series of books, and the Walt Disney television program. What is astonishing is that Von Braun's scenario is still valid today.
	MPK	This first serious examination in the Soviet Union of manned flight to Mars was made by M Tikhonravov. His Martian Piloted Complex (MPK) would have a mass of 1,630 metric tons and land a crew on Mars on a 30-month expedition.
	Von Braun Mars Expedition - 1956	Von Braun's Mars expedition presented in the 1956 book he co-authored with Willy Ley, The Exploration of Mars, was vastly reduced in scope from the 1952 version. Obviously facing incredulity at the awesome scope of the first expedition concept - 70 crew aboard ten spacecraft - Ley and Von Braun cut the expedition to just two ships, 12 crew, and cut the mass of those ships in half compared to the earlier designs.
	Stuhlinger Mars 1957	In 1954 Ernst Stuhlinger conceived the first Mars expedition using solar-electric propulsion. A nuclear reactor or solar collector would drive a turbine to provide electricity that would drive an ion engine using cesium propellant. The concept was studied at the US Army Ballistic Missile Agency from 1953 to 1959 and portrayed to a wide public in Walt Disney's broadcast of 4 December 1957. In the Disney presentation, Stuhlinger imagined a ten-ship expedition that would take 200 crew to the red planet.
	TMK-1	In 1959 a group of enthusiasts in OKB-1 Section 3 under the management of G U Maksimov started engineering design of this first fantastic project for manned interplanetary travel. The 75 metric ton TMK-1 spacecraft would take a crew of three on a Mars flyby mission. After a 10.5 month flight the crew would race past Mars, dropping remote controlled landers, and then be flung into an earth-return trajectory. The first flight to Mars of the TMK-1 was planned to begin on June 8, 1971, with the crew returning to the earth on July 10, 1974, after a voyage of three years, one month, and two days.
	Bono Manned Mars Vehicle	In 1960 Philip Bono, then working at Boeing, proposed a single-launch Mars manned expedition. Bono's scenario was the classic trade-off of weight for risk. However it was feasible, and showed that Mars expeditions need not be assembled by multiple launches in earth orbit.
	Mars Expedition NASA Lewis 1960	The first NASA study of a manned Mars expedition outlined an opposition-class, nuclear thermal rocket powered spacecraft that would take seven astronauts to the planet's surface for 40 days. Radiation protection of the crew was a major concern.
	TMK-E	Feoktistov felt that the TMK-1 manned Mars flyby design was too limited. His design group proposed in 1960 a complete Mars landing expedition, to be assembled in earth orbit using two or more N1 launches. The spacecraft would be powered by nuclear electric engines, with the reactor moved away from the crew quarters on long telescoping booms. Five landers would deliver a nuclear-powered 'Mars Train' on the surface for a one-year survey of the terrain. The design would be heavily modified as the 1960's progressed, as research showed the Martian atmosphere to be much thinner and the nuclear electric engines to be less efficient than assumed.
	EMPIRE Aeronutronic	Aeronutronic's Mars flyby spacecraft design of 1962 had a total mass of 170 metric tons and would be launched into low earth orbit with a single launch of a Nova booster. The 21-month mission would be launched toward Mars during a 28 day window opening on 19 July 1970.
	EMPIRE General Dynamics	General Dynamics' manned Mars orbiter spacecraft design of 1962 had a total mass of 900 metric tons and would be launched into low earth orbit with a two launches of a Nova booster or eight launches of a Saturn V. The 15-month mission would be launched toward Mars in March 1975.
	EMPIRE Lockheed	Lockheed's manned Mars flyby spacecraft design of 1962 had a total mass of 100 metric tons. Taking advantage of Apollo technology, it would be launched into low earth orbit with a single launch of a Saturn V booster. The 22-month mission would be launched toward Mars on 24 September 1974.
	Stuhlinger Mars 1962	By 1962 Ernst Stuhlinger's ion-drive Mars expedition had evolved within the Research Projects Division into five 150 m long spacecraft, housing a total crew of 15. A much shorter 475 day mission time was planned.
	Faget Mars Expedition	NASA Houston supported a conference in May 1963 which examined a number of Mars expedition scenarios. It was found that, given the same assumptions regarding the separate lander vehicle, a Mars landing spacecraft could vary from 270 to 1140 metric tons in low earth orbit, depending on the type of propulsion and mission scenario.
	Mavr	A variation of the TMK-1 scenario by Maksimov's unit would still use a single N1 launch. However a flyby of Venus would be undertaken on the return voyage from Mars. This would reduce both flight time and the earth-return velocity. The project was given the code name "Mavr" ('Moor' or MArs - VeneRa).
	TRW Mars	In 1963 TRW designed a Mars expedition using aerobraking at both Mars and Earth, and a swingby of Venus on return. It found that this approach could reduce the expedition mass in low earth orbit by a factor of five, allowing chemical propulsion to be used.
	Project Deimos	Project Deimos was a Mars expedition proposed by Philip Bono in the mid-1960's. It would use the huge Rombus single-stage-to-orbit booster, refueled in earth orbit, as the propulsion system to Mars and back. Separate Mars landers would bring crews to explore the Martian surface.
	UMPIRE Convair	Unfavorable Manned Planetary - Interplanetary Roundtrip Expedition profiles were studied under NASA Huntsville contracts to General Dynamics and Douglas in June 1963.
	UMPIRE Douglas	Unfavorable Manned Planetary - Interplanetary Roundtrip Expedition profiles were studied under NASA Huntsville contracts to General Dynamics and Douglas in June 1963.
	MORL Mars Flyby	Near-term manned Mars flyby spacecraft proposed by Douglas in 1965 for flight as early as 1973. It differed from the contemporary NASA in-house design in using the Douglas Manned Orbiting Research Laboratory as the basis for the habitation module.
	FLEM	A Mars expedition concept where the lander would separate from a manned Mars flyby spacecraft, aerobrake directly into the Martian atmosphere, land on the surface, and then place itself into solar orbit, and rendezvous and dock with the flyby spacecraft. Since the main spacecraft would not have to brake into and out of Mars orbit, huge propellant savings were possible, making a manned Mars landing expedition possible in a single Saturn V launch.
	KK	Work on the TMK project continued, including trajectory trade-off studies and refinement of the design. In its final iteration, in May 1966, before Korolev's OKB was overwhelmed by N1-L3 development work, the design was known as the KK - Space Complex for Delivering a Piloted Expedition to Mars. Nuclear-electric propulsion was retained, but various mission designs were studied in an attempt to reduce the overall vehicle mass.
	IMIS 1968	In January 1968 Boeing issued a report that was the result of a 14 month study on manned Mars missions. The Integrated Manned Interplanetary Spacecraft represented the culmination of a decade of NASA studies and became the starting point when manned Mars studies would resume in the 1980's. The Boeing spacecraft for the Mars mission used five modular PPM Nerva nuclear thermal rocket stages to boost several unmanned probes, a manned MEM lander, a MM Mission Module crew compartment, and a biconic EEM Earth Entry Module for re-entry into the earth's atmosphere at the end of the mission. The modular, flexible IMIS design could accomplish 15 of the 20 mission opportunities to Mars and Venus in the 1975-1980 time period.
	MEK	The Mars Expeditionary Complex (MEK) was designed to take a crew of from three to six to Mars and back with a total mission duration of 630 days. Primary spacecraft propulsion was to be 15 MW nuclear-electric engines with liquid fuel auxiliaries.
	Von Braun Mars Expedition - 1969	Von Braun's final vision for a manned expedition to Mars was a robust plan that eliminated much of the risk of other scenarios. Two ships would fly in convoy from earth orbit to Mars and back. They were entirely reusable for future expeditions, the only element being expendable being the Mars Excursion Module used to visit the planet's surface. This was Von Braun's last attempt to convince the American government to finance his dream. Five months later he would be sidelined to a dead-end headquarters job at NASA, and leave the Agency two years after that.
	NASA Mars Expedition 1971	Final NASA Mars expedition before the 1980's. The spacecraft would use shuttle hardware, including SSME engines in the rocket stages.
	MK-700	Chelomei was the only Chief Designer to complete an Aelita draft project and present it to the Soviet government. He proposed two launches of the enormous UR-700M launch vehicle to assemble a 1400 metric ton MK-700 spacecraft in earth orbit. Nuclear thermal stages allowed a net functional payload (living quarters, Mars landers, earth return capsule) of 250 metric tons. A government expert commission reviewed the preliminary draft project for the UR-700M launch vehicle and MK-700 spacecraft in 1972. Based on the decades worth of development and tens of billions or rubles required, the state commission recommended that further work on manned Mars expeditions be deferred indefinitely.
	Mars 1986	NPO Energia resumed study of a Mars project once development began of the new Energia booster in place of the cancelled N1. The 1978-1986 study used some of the ideas and technical results of the 1969 study, but modified according to technical developments of the period.
	Mars via Solar Sail	In 1982 a minimum-mass approach to a Mars expedition was proposed, using aerocapture at Mars and the use of a long-duration solar sail cargo transport.
	Planetary Society Mars Expedition 1983	Chemically-powered Mars flyby-rendezvous landing mission designed by SAIC under contract to the Planetary Society in 1983. The risky scenario involved only one chance for the crew to rendezvous and dock with an unmanned Earth Return Vehicle as it whizzed by Mars. The 1096 day mission would depart on 5 June 2003.
	Case for Mars II	The Case for Mars II Mars expedition plan was presented at a conference on 10-14 July 1984. This proposed the establishment of a permanent space infrastructure to ensure safe and economical exploration of Mars. It pulled together all of the elements proposed by Mars enthusiasts to minimize spacecraft mass and eliminate expendable hardware: aerobraking, a flyby-rendezvous mission scenario, Mars Cyclers, and in-situ resource utilization (ISRU) to produce propellants on the Martian surface.
	Lagrangian Interplanetary Shuttle Vehicle	A Lagrangian approach to Mars exploration was proposed in June 1985. This would use the L1 sunward point of equal Earth/Moon/Sun gravity to assemble and refuel a large Interplanetary Shuttle Vehicle spacecraft.
	Pioneering the Space Frontier	In 1984 a National Commission on Space was formed, with ex-NASA Administrator Thomas Paine at its head. Its report, Pioneering the Space Frontier, was therefore similar to the ambitious plans Paine had proposed in 1969. The cost of just establishing the infrastructure in the 1995-2020 period leading to a Mars expedition in 2026 was estimated at $700 billion. As with Paine's 1969 effort, all of this was much too ambitious, and the plan was never remotely considered by anyone in the legislative or executive branches of government.
	Ride Report	Former astronaut Sally Ride was asked to head a task force to formulate a new NASA strategic plan in August 1986. The Ride Report was issued in August 1987, and proposed a Mars Exploration Plan that took an evolutionary approach leading to the first Mars landing in 2005.
	Mars Evolution 1988	In 1988 NASA made four case studies of a rapid response to the threat of a Soviet manned expedition to Mars. The Mars Evolution case study built a capability that would lead to the development of a self-sufficient, sustained human presence beyond low-Earth orbit. This was accomplished in two phases: the establishment of a permanently staffed facility on the Moon, progressing to the establishment of a similar outpost on Mars. A substantial infrastructure would include production of oxygen on the moon and rocket propellants on Phobos and Deimos. Electric Cargo Vehicles would move payloads from low earth orbit to the moon, and from the moon to Mars. Only after a substantial infrastructure was built up in Mars orbit, would landings take place, at around 2010.
	Mars Expedition 88	In 1988, in response to a perceived Soviet plan to start a new space race to Mars, NASA made in depth case studies of a rapid US response. The primary objective of the Human Expedition to Mars three-mission set was to send the first human explorers to the Martian surface in order to capture early leadership in the piloted exploration of the solar system. Once there, the crew would conduct local geological reconnaissance, emplace long-lived geophysical instruments, and collect samples for return to Earth. An additional key objective was to conduct ancillary exploration of the Martian moons, Phobos and Deimos.
	Phobos Expedition 88	Human Expedition to Phobos was one of four in-depth NASA case studies in 1988 in response to a perceived imminent Soviet manned Mars program. A primary objective of the mission was the establishment of early leadership in the human exploration of the solar system. To that end, baseline vehicles were designed for minimum dependence on advanced technology, and human presence was extended only to Mars orbit and the surface of Phobos. The study found that the Phobos mission could be an excellent precursor to a piloted Mars landing mission. Most importantly, it allowed a "Mars class" mission to be accomplished by 2003, four and a half years before the first Mars landing of the all-up Mars expedition case.
	90 Day Study	Following the Ride Report, the Bush administration indicated a willingness to support a new manned space initiative after completion of the space station. To provide alternates for presidential consideration, NASA management completed a 90-day study in October 1989. This estimated the cost of going to Mars as $ 258 billion (including $141 billion contingency). The plan used the then-current collection of planned NASA infrastructure hardware - Space Station Freedom, Orbital Transfer Vehicles, aerobraking to accomplish the mission.
	Mars 1989	In 1989 yet another Mars project was proposed by NPO Energia. The spacecraft hardware was essentially that of the 1986 design, in place of the nuclear reactor of previous designs power would be generated by huge farms of solar panels, developed from those on the Salyut 7 and Mir stations.
	Mars Evolution 1989	In 1989 NASA's Mars Evolution case study examined one approach to develop a permanent, largely self-sufficient Mars outpost with significant scientific research capability. Ground rules for this case study stipulated that space transfer vehicles would be assembled at a free-flying man-tended assembly fixture co-orbiting with Space Station Freedom in low Earth orbit, and aerobraking techniques would be used at both Mars and Earth. Artificial gravity would be provided in the spacecraft that transport the crew to and from Mars.
	Mars Expedition 89	The primary objective of the 1989 Mars Expedition case study was to determine how to accomplish a single human expedition to the surface of Mars as early in the 21st century as practical. The preferred option was now an "all-up" approach in which the crew and all the cargo were dispatched on one vehicle. The 1989 Mars expedition case study ground rules included: a single expendable vehicle would be launched to low Earth orbit; a zero-gravity vehicle would be used; three crew members would descend to the surface for 20 days; and aerobraking would be used at Mars.
	Mars Direct	In 1991 Martin Marietta and NASA Ames (Zubrin, Baker, and Gwynne) proposed 'Mars Direct' - a Mars expedition faster, cheaper, and better than the standard NASA plan.
	Mars Semi-Direct 1991	Mars Semi-Direct was a NASA concept bridge between Zubrin's Mars Direct and NASA's Design Reference Mission 1.0. It was essentially a low-cost version of Boeing's STCAEM.
	STCAEM Cryogenic AeroBrake	The STCAEM cryogenic / aerobrake (CAB) concept was used as the NASA reference vehicle. It offered conceptual continuity with the mainstream Mars transportation studies performed over the previous several years. Its only major new technology development was high-energy aerobraking (HEAB) for planetary capture, but the concept also required a high-thrust cryogenic space engine. Being able to land on Mars using the CAB concept required a successful rendezvous between separately captured vehicles in Mars orbit. The vehicle consisted of three main elements: the Mars Excursion vehicle (MEV), the Mars Transfer Vehicle (MTV) and the Trans-Mars Injection Stage (TMIS).
	STCAEM NEP	The STCAEM Nuclear Electric Propulsion (NEP) Mars transfer concept offered advantages of a reusable, extremely high Specific Impulse (Isp = 10,000 sec) system; a fully propulsive capture at Mars and Earth which avoided the need for high energy aerobraking; great mission flexibility (relative insensitivity to mission opportunity, capture orbit astrodynamics, or changes in payload mass); and low resupply mass (the argon propellant amounted to roughly a third of total vehicle mass). Disadvantages of the concept were its high technology development cost with a complex, high-performance power system and large, liquid-metal radiator system.
	STCAEM NTR	The STCAEM nuclear thermal rocket (NTR) concept offered advantages of higher Isp than cryogenic concepts, fully propulsive capture at Mars and Earth to avoid high energy aerobraking, and the potential for recovery and re-use of the expensive transfer habitation system. NTR represented a proven technology; early versions were extensively tested in the 1960s and early 1970s.
	STCAEM SEP	The solar electric propulsion (SEP) Mars transfer concept was the only non-nuclear advanced propulsion option in the STCAEM study. It offered advantages of the lowest IMLEO of the four reference vehicles; a reusable, extremely high Isp (5,000 sec) system; a fully propulsive capture at Mars and Earth which avoided the need for high energy aerobraking; good mission flexibility (relative insensitivity to mission opportunity, capture orbit astrodynamics, or changes in payload mass); and low resupply mass (the argon propellant required amounted to roughly a third of total vehicle mass). Disadvantages included uncertainty of the cost of production of acres of solar arrays, and the need to deploy and control a relatively fragile vehicle, which was bigger than six football fields, in space.
	Synthesis Study	On 11 May 1991 President Bush declared that he would support a Space Exploration Initiative program leading to a Mars Landing by 2014. To coincide with the announcement, the SEI Synthesis Group issued a report America on the Threshold that foresaw Mars expeditions based once again on nuclear thermal propulsion.
	ERTA	ERTA (Elecktro-Raketniy Transportniy Apparat) was a nuclear-electric space tug designed to be boosted on medium boosters and provide both propulsion and electrical power for unmanned planetary probes.
	Design Reference Mission 1	The Design Reference Mission 1.0 was the Space Exploration Initiative's last gasp. The plan, unveiled in May 1993, was a NASA version of Zubrin's Mars Direct, using larger spacecraft, but compensating for this by using nuclear thermal instead of chemical propulsion. Six crew would be sent on a conjunction class trajectory to Mars, with propellant for the return trip being obtained by an ISRU propellant plant on the surface.
	Mars 1994	Soviet / Russian design for a Mars expedition powered by RD-0410 bi-modal nuclear thermal engines. A crew of five would complete the trip to Mars and back in 460 days.
	Mars Together	In 1994-95, RKK Energia, and NASA's Jet Propulsion Laboratory analyzed the project 'Mars Together'. This studied the use of spacecraft using solar arrays or nuclear reactors of up to 30 to 40 kW for insertion into Martian orbit and operation of a side-looking radar to digitally map the surface. As a preliminary step a demonstration launch was proposed of a spacecraft with a mass of 120 to 150 kg, a solar panel area of 30 square meters and engines with a thrust of 3 kW. Objectives of the experiment would be understanding of the changing of the orbital altitude with continuous work of the ion engine for several hundred hours.
	Athena	In 1996 Robert Zubrin proposed a new version of a manned Mars flyby mission, dubbed Athena. Unlike previous fly-by concepts, Athena would remain in the vicinity of Mars for a year while the crew remotely operated probes of the Martian surface and atmosphere. This would eliminate the round-trip radio time lag of ten to forty minutes in trying to operate such probes from the earth.
	Design Reference Mission 3	This July 1997 DRM was a subscale version of the original, with a scrub of the original payloads to reduce mass wherever possible. An integral pressure structure and heat shield was proposed for the lander, requiring the use of lighter composite structural materials. The stages would be launched without the spacecraft, meaning more launches would be required, but development of a monster heavy lift vehicle would not be needed. There would be 8 launches of a shuttle-derived vehicle with an 85 metric ton payload, consisting of three nuclear stages and three spacecraft on the first launch opportunity. At the next opportunity two more launches would put a fourth nuclear stage and the manned spacecraft in orbit. The total mass hurled toward Mars would be 303 metric tons, 75 metric tons less than the 1993 DRM.
	Combo Lander Mission	During the spring of 1998, NASA conducted a special study to design a human Mars mission that could be accommodated for launch by three heavy-lift launch vehicles. The design team was directed to employ a solar electric propulsion (SEP) stage for delivering the Mars mission elements to a high apogee Earth departure orbit and to not employ nuclear propulsion for any maneuvers. The study was unusual in the approach of designing to a fixed constraint for Earth launch mass. The most significant result was the identification of the technology challenges that had to be met to achieve the launch mass goal.
	Design Reference Mission 4 NTR	The design reference mission 4.0 took into account all of the changes in payload masses as a result of further study of individual elements. Overall mass required in low earth orbit was reduced only slightly, by 2.5%. The use of NTR bimodal propulsion, with a single nuclear reactor that provided both propulsion and electrical power during space operations, in lieu of a separate power source, was made baseline. Cryo/aerobrake and solar electric options were retained.
	Design Reference Mission 4 SEP	In 1998 NASA Lewis studied a Solar Electric Transfer Vehicle for use in a Mars Expedition. This would never leave earth orbit yet provide most of the delta-V to send a spacecraft toward Mars. Only five shuttle-derived vehicles would be required to put the expedition into low earth orbit versus eight required in the 1997 Design Reference Mission. Removing the backup habitat lander saved two of these launches. The other launch was saved by eliminating the four nuclear thermal rocket stages needed in the 1993 and 1997 DRM's and replacing them with SETV's and three chemical stages.
	Dual Lander Mission	After some discussion within NASA, in the Combo Lander mission was found to be too lean. It was again reformulated as a Design Reference-Mission type with two landers, six crew sent on two different opportunities, and ISRU production on the surface, and split cargo/crew landers to provide more redundancy. Even with the mass-saving advanced technology assumptions of the Combo Lander study, this drove the total mass required in Low Earth Orbit back to 600 metric tons, and the number of heavy lift launch vehicle launches to 12.
	Mars Society Mission	In 1999 the Mars Society, noting certain defects in NASA's Design Reference Mission, requested California Institute of Technology to develop an alternative scenario to meet these concerns. Crew was reduced from six to five. The mission design featured increased commonality to reduce the number of new spacecraft to be developed; redundancy to improve mission safety; a heavy-lift launch vehicle family based on newer Delta-IV technology; improved trajectories; no more than one earth-orbit rendezvous; and no nuclear rocket development (although nuclear power on the Martian surface was still proposed).
	Marpost	In December 2000 Leonid Gorshkov of RKK Energia proposed a manned Mars orbital expedition as an alternative to Russian participation in the International Space Station. The expedition would also provide the means for reviving Russian ascendancy in space. The Marpost (Mars Piloted Orbital Station) spacecraft would have a total mass of 400 metric tons and be assembled in low earth orbit from components assembled in four launches of a revived Energia launch vehicle.
	European Mars Mission	In 2005 the Mars Society Germany proposed a European Mars Mission (EMM) that could be launched using an improved version of the Ariane 5 booster. The split mission approach was adopted to allow launch of payloads launched directly by this booster from Earth to Mars. Cargo elements would be transferred on low energy, longer transit time trajectories, with only the crew element being sent on a high-energy, fast-transit trajectory. The launches needed to support a mission were spread across two launch windows to allow the Mars surface infrastructure to be pre-positioned and checked out prior to committing crews to the mission.
	Mars Oz	2001 design study by the Mars Society Australia that incorporated many innovative elements to produce a minimum-mass non-nuclear Mars expedition concept.