What it was: Two separate, competing Mars flyby/lander missions (with the same name) from OKB-1, synthesized into a Mars/Venus flyby mission that was the original purpose of the N1.
Details: Wernher von Braun was famously focused on Mars for much of his life, so it’s no surprise that there were two serious proposals to send American astronauts to our next neighbour out during his heyday at NASA. Less well-known is that Sergei Korolev was likewise enamoured of a Mars mission. When the N1 rocket was first floated in 1956, it was quite specifically intended as a launcher for Korolev’s early partner Mikhail Tikhonravov’s proposal of the MPK (марсианского пилотируемого комплекса, “Mars Piloted Complex”). The MPK spacecraft was wildly ambitious—a 1630 tonne ship requiring 20 to 25 N1 launches!—and never even got to the point of sketch plans.
The basic reason for the MPK’s enormous mass was that it was both a landing mission and relied on chemical propulsion. That implied two possible routes out of the dilemma, and in the wake of Korolev and OKB-1’s success with Sputnik, work got underway on studying both under the umbrella name of TMK (Тяжелый Межпланетный Корабль, “Heavy Interplanetary Spacecraft”). One group headed by Konstantin Feoktistov—later famous as a member of the first multi-person crew aboard Voskhod-1—studied an ion-propulsion driven landing mission, while Gleb Maksimov spearheaded a conventionally propelled flyby craft.
Feoktitsov’s TMK settled on a nuclear reactor to power a “slow but steady wins the race” approach that would spiral up, unmanned, through the Van Allen radiation belts. A conventionally launched mission would sprint through the belts and catch up, depositing cosmonauts aboard this spindly-looking ion drive-driven craft for the long journey to Mars. This arrangement initiated one “look” for Soviet and Russian long-term manned missions since then: the dangerous reactor, its engine, and the necessary cooling vanes were all arrayed along a long boom that kept them away from the fragile men aboard.
Maximov’s TMK was far more conservative from a modern perspective, and actually somewhat resembles both the MVF and Skylab. This was the option selected for moving forward. By the end of 1961 the basic parameters of the craft were settled and the mission tentatively aimed at leaving Earth on June 8, 1971 and returning on July 10, 1974—by far the longest manned mission seriously considered of which the author is aware, topping even the Triple Flyby variant of NASA’s MVF.
During coast and flyby it would have been 12 meters in length and weighed 35 tonnes—prior to Mars injection this would have been 75 tonnes including propellant, hence accounting for the lifting capability of a single N1. There would have been 50 cubic meters of space inside, split evenly between habitation and work space. A visual-light telescope for astronomical observations was attached to the side, a communications antenna to the fore, and a spread of solar panels girdled it. During coast the craft would have rotated end-over-end for a bit of artificial gravity, and during flyby there was an unmanned probe to drop off for landing. At the end of the mission a return capsule, nestled in the aft end to that point, would bring the cosmonauts back to the ground.
Both life support and food would have been dependent upon a greenhouse based on Chlorella chlorophyte algae, which was calculated to give better value for mass than chemical oxygen plants: 27 kilograms of oxygen per day per kilogram of algae. The food it made would have been supplemented partly by prepared stores. Getting this plant (no pun intended) up and running was considered the key breakthrough needed for the craft, and considerable work was done through the 1960s. Three men were sealed into a close-looped simulator ecosystem based on it in 1967.
A mockup of the MAVR (MArs-VeneRa) itself—as TMK-1 was renamed once a Mars/Venus flyby path was found that was shorter than the 1000-day mission mentioned above—was begun in 1964 but foundered due to zero funding.
What happened to make it fail: MAVR was ready to roll as exactly the wrong time. Khrushchev had grown disenchanted with Korolev’s follow-up to the R-7 missile, the R-9, and instead was coming to favour the line of storable-propellant missiles developed by Mikhail Yangel. Vladimir Chelomei jumped on this and proposed his own set of manned spacecraft, one of which was for interplanetary voyages, after poaching engine designer Valentin Glushko from Korolev to build his own rockets.
By the time Korolev regained control of the Soviet manned space program he and his nation’s leaders had decided that the gauntlet thrown down by Kennedy for a race to the Moon was serious, and moreover that they should pick it up. The N1 was “stretched” to become a Moon rocket, the Mars mission was put off into the indefinite future, and the rest is history.
What was necessary for it to succeed: Getting people to Mars has turned out to be far harder than expected, so the breezy optimism that had the MAVR at Mars by the mid-1970s is hard to sustain. A lot of things went against it: the early-60s infighting in the Soviet space program, disinterest in space on the part of the Soviet military, Korolev’s egotistic insistence on going head-to-head with Apollo, the shift in the USSR’s manned spaceflight focus to shuttle and space station during the 70s…the list goes on.
One thing that would have cleaned up a lot of them, or at least softened their impact, was the transfer of the space program away from the Soviet military, in particular the GRAU which funded the rockets. They wanted missiles not launch vehicles, and so logically if Khrushchev has been serious about wanting a space program he would have accepted a proposal from Korolev made post-Sputnik that OKB-1 be reorganized as a civilian organization like NASA. It didn’t happen.
One more note: long-time readers with good memories might have noted that the initial dates selected for the mission (though it was extraordinarily unlikely that the Soviets could have hit their targets) were roughly similar to those mentioned in our discussion of the NASA Mars-Venus Flyby. As mentioned in that post, there was a tremendous solar flare in 1972 that, by NASA’s estimate, would have hit anyone outside of the Earth’s protective magnetosphere with roughly 4 grays of radiation, with death resulting in the next few weeks.
A fine image of what MAVR might have looked like as it passed Mars can be seen on the Deviantart page of Polish artist Maciej Rebisz.