Everybody knows and loves the Antonov An-225 Mriya, the world’s heaviest and arguably largest aircraft. Many know about its primary purpose – the airplane was originally designed to transport the Buran, the Soviet space shuttle. But that was not the only space-related function the behemoth of the skies was intended to perform. It could also act as an aerial launch platform.

The spaceplane intended for it often gets undeservedly overlooked. It was developed under the project called Multipurpose Aerospace System (MAKS), and if its designers could really do everything they promised, it had somewhat of a potential to revolutionize space travel.

Designing the miniature shuttle

The Soviet space plane building efforts were kick-started in the early 1960s, after their intelligence revealed the American plans to build the Boeing X-20 Dyna-Soar, which would have become the first reusable space vehicle. Spaceplanes had a lot of military potential, as they allowed not only rapid deployment and retrieval of satellites, but could function as genuine orbital bombers. Project Spiral followed, mainly run by the Molnia design bureau. 

A lot of research was conducted and several prototypes were constructed, but none of the numerous tests were very successful. They paved the way for the Buran though, and in the 70s the Spiral was canceled in its favor. But the idea to have a smaller, more flexible space plane never went away. As soon as the Buran was finished, the Molniya design bureau started working on its small sibling.

Already in the 60s, when thinking of their answer to the X-20, Soviet scientists decided that launching spaceplanes with hypersonic reusable aircraft would be a lot more efficient than using conventional rockets. Due to the lack of hypersonic engines at the time, the first real candidate to aerially launch the Spiral was the Sukhoi T-4 supersonic bomber, but it too never materialized, which – in part – contributed to the failure of the Spiral program.

So, something less ambitious would have to be used. Energia already had a candidate for that: the An-225, which – under development at Antonov at the time – was already adapted for carrying heavy loads on its back. The only requirement was to include a possibility to detach those loads mid-flight.

MAKS mock-up
Mock-up of the MAKS spaceplane. Late 80s. (Image: testpilot.ru)

Big promises

By 1988, the conceptual design phase of the MAKS was complete, and the Mriya – which performed its maiden flight the same year – was ready. The space plane was a direct descendant of the Spiral project and its many designs, but included all the advancements made while developing the Buran.

It was supposed to come in three variants: the MAKS-OS-P, a spaceplane capable of carrying a crew of two and 7 tons of cargo, coupled with a disposable fuel tank attached to the nose of the aircraft; the MAKS-T, a robotic variant with a payload capacity of 14 tons, and the MAKS-M, a fully-reusable variant without the disposable fuel tank. 

The last variant did not receive a lot of attention and was eventually abandoned, but the first two reached the stage of a mockup, and if not for the collapse of the Soviet Union, would have likely become the workhorse of the Soviet space program. 

Of course, they were a far cry from the Space Shuttle and the Buran with their payload capacities of 25 tons and 30 tons respectively. But the MAKS had its fair share of advantages.

The aerial launch meant an ability to launch to any orbit, at any time, from any airfield large enough to accommodate the An-225. The system was much more compact and therefore much more flexible, negating the need to wait for a launch window. It would also not depend on weather conditions, as the launch of the spacecraft would be performed way above the clouds. 

In a routine launch, the An-225 would carry the MAKS up to the altitude of approximately 11,000 meters (36,000 ft), at which point the spaceplane would detach and ignite its liquid-fuel thrusters. The fuel tank would be detached upon reaching the required orbit, and after the mission is complete, the spaceplane would return to the airfield. 

It could be used for both deploying and retrieving satellites, repairing them, delivering people and payload to space stations, and in general doing anything full-sized space shuttles do, but on a smaller scale and a lot quicker. 

The price was another huge selling point. By a recent estimate, it would cost approximately $1,200 to deliver a kilogram of payload on MAKS to a low-earth orbit: ten times less than with the Space Shuttle at the time, and twice less than with the SpaceX Falcon 9 today. Of course, there is always a question if such a figure could be trusted, as it seems a bit too small to be realistic. But there is no denying that aerial launch, especially if the platform is already operational, can be relatively cheap. 

Mriya launches MAKS
Antonov An-225 Mriya launches MAKS. Artist's impression. (Image: Вадим Лукашевич / Владимир Некрасов / Buran.ru)

The last days

The entire Soviet industry went into a deep crisis after the dissolution of the Soviet Union, when the economy plummeted and government funding ran dry. But in many cases, the designers did not lose spirit. 

The MAKS program ran through the entire decade, being shown off at numerous airshows and collecting at least several engineering prizes. The spaceplane itself remained relatively unchanged through the process, but the plans regarding the aerial launch platform were a lot less stable.

Even in the late 80s, the An-225 was considered as an interim solution to the problem of aerial launches: it was, after all, just a heavy transport plane manufactured by deeply modifying the An-124 Ruslan. A dedicated aircraft would suit a lot better, and the Soviet and post-Soviet aircraft industry had no shortage of plans for those.

The prime contender was the An-325, a further evolution of the Mriya, more powerful and better adapted for launching spacecraft. It would have had two additional engines, an enlarged and improved airframe, additional fuel tanks, and an option for aerial refueling. This super-Mriya never reached the advanced design stage, but its story is still an interesting one and deserves to be told at another time.

There also was the Molnia-1000 Heracles, a twin-fuselage monstrosity that could double as a transport aircraft and even as an airliner with a special pod attached. Also, a twin-fuselage Mriya was in the works for some time: possibly the craziest modification of the venerable Ukrainian plane. Of course, neither of them were built. 

By the late 90s the only flying Mriya was abandoned, and Antonov lost all hope to finish the second one. Purpose-built motherships were out of the option too, so, it was considered to use other options – the Tupolev Tu-160 and Tu-22M supersonic bombers, the Myasishchev M-55 research aircraft, even the MiG-31 fighter jet. Some of them were by far too small to carry the MAKS in its original configuration and would have probably necessitated substantial modification.

Through the 90s and the early 2000s, various Russian research institutions spent $1.5 billion on the program, showing that it was really taken quite seriously, but that was not enough. It reappeared briefly in 2012, when Molnia offered it as a space tourism platform, but failed to find investors. 

It is very unlikely the MAKS will ever be resurrected in the nearest future, with the rise of conventional reusable rockets and the death of other aerial launch projects, such as Scaled Composites StratoLaunch (which recently got turned into a testing platform for hypersonic research). But looking back at it, it really looks like the miniature Buran had a lot of potential. Maybe, just maybe, at some point in time somebody will remember the amount of money and research that went into the project and dust it off.