In 1962, Sergey Korolev, the head of the Soviet rocket program, wrote a report entitled “A Plan for the Mastery of Mars and Venus”. In the previous two years, his team had made several unsuccessful attempts to send “automatic stations” to Mars and Venus. Now he tasked Maksimov’s design team with the problem of sending men on orbital missions to the nearby planets.

Gleb Maksimov had designed Luna-3 and Venera-1. The Mars-1 spacecraft was an example of his modular spacecraft system, able to perform photographic fly-bys of Mars or Venus or to deliver a landing capsule. Although very young at the time, Maksimov had earned the respect of Korolev’s team and the academic scientists who designed experiments for planetary probes.

Maksimov’s manned spacecraft design became known as TMK, the heavy interplanetary ship (Tyazhely Mezhplanetny Korabl ). The 75 ton spacecraft would have to be assembled in space from pieces launched by the as yet unbuilt N-1 moon rocket.

A subsequent version would include crew quarters and a hydroponic greenhouse to supply food and oxygen and artificial gravety generated by the rotation of the spacecraft around the longitudinal axis. The ZBTK (Closed Biological-Technical Complex) was developed and ground tested, wth several Russian scientists spending a year inside a sealed environment — long before the infamous Biosphere experiments in the west.

The ship was to be propelled by the YaERD-2200, an 8.5 ton-thrust electro-plasma engine. With a specific impulse 20 times higher than chemical rocket engines, the craft would be able to travel to Mars or Venus, enter orbit, leave orbit and return to Earth. The thrust was relatively low, and the craft would begin by spirally out from low earth orbit, the crew flying up and getting onboard once the ship was safely above the Van Allen radiation belts.

Ion engines were an idea that appeared earlier than many people realize. Robert Goddard had built experimental ion engines as early as 1916, before the first flight of a liquid-fueled rocket. In 1964, the Soviet Mars probe Zond-2 had tested the first plasma engines in space. Russia developed the technology of Hall-effect acceleration of plasma, still used today for satellite orientation and on the European SMART-1 lunar probe.

The YaERD-2200 engine would have been powered by a 2200 kilowatt nuclear reactor, using thermionic emission to generate electricity directly from incandescent uranium oxide fuel elements. The Russians later did develop smaller thermionic reactors such as Topaz-1, which was orbited and tested in combination with ion engines. The program became controversial after a nuclear satellite reentered the atmosphere and crashed in Canada.

Today, the technology of building large, long-lasting structures in low earth orbit is much better understood. A perminent mobile laboratory, powered by nuclear fission and ion propulsion could be built and used to roam the solar system. But many technical problems remain, including the protection of the crew during solar radiation outbursts.

Recently, the American astronaut Buzz Aldrin has been calling for work to begin on an a modern version of the TMK concept, which he calls the Exploration Module or XM.