The Spiral project was not cancelled with the decision to proceed with the large Buran spaceplane. Instead flight test of the orbiter continued but the launcher design was rethought. The ambitious Mach 4 air-breathing first stage was abandoned in favour of launch from an existing subsonic heavy transport. The first iteration of the new design was undertaken in 1977-1978 as the AKS project at the Scientific Research Institute 'Rosa'. This used the second rocket stage and orbiter stage of Spiral, designated RUOS in this study. This design was the starting point that would evolve through the System 49 and Bizan designs, finally resulting in the MAKS of 1988.

The System 49 design had the same arrangement as Spiral. The rocket stages and the Spiral orbiter were mounted on the back of an An-124 subsonic transport. By the time of the design, the Spiral configuration had been proven in the MiG-105-11 and BOR-4. The combined orbiter and rocket stages, weight 200 tonnes, would be launched at an altitude of 10 km and a speed of Mach 0.7. Effective velocity gain compared to a vertical launch from the ground was 270 m/s.

The first stage would use Lox/Kerosene propellants and 2 NK-43 / 11D112 engines. The second stage was equipped with a single RD-57M / 11D57M engine burning Lox/LH2 propellants. Two rocket stage layouts were studied: a traditional tandem scheme, and a 'piston' / 'wrap around' concept, where the toroidal propellant tanks of the first stage surrounded the second stage.

The orbiter would have a mass of 13 tonnes, and could deliver a payload of 4 tonnes to orbit in a 27 cubic metre payload compartment (dimensions 6.0 m long x 2.8 m x 1.6 m). Orbits from 120 to 1000 km altitude, and 45 to 94 degrees inclination could be achieved thanks to the flexibility of airborne launch. The orbiter was flown by a single pilot, had sufficient consumables for 5 to 12 hours of on-orbit operations, and was designed for 100 reuses. It could achieve up to 1000 km cross-range during re-entry and landed at a speed of 300 to 310 km/hr.

The design was found to be feasible but to have little growth potential. Greater payload could only be achieved by the completely different 49M using a new super-heavy carrier aircraft and orbiter. Therefore it was succeeded in the design studies by the 'Bizan' concept.

High resolution photo reconnaissance satellite; returned film capsule; maneuverable. References: 1 , 2 , 6 .

Acquisition of meteorological information needed for use by the weather service. References: 1 , 2 , 5 , 6 .

Boeing 747 shuttle carrier aircraft delivered to Edwards References: 15 .

Area survey photo reconnaissance satellite; returned film capsule. References: 1 , 2 , 6 .

Military navigation satellite. References: 1 , 2 , 5 , 6 .

Complete aft fuselage assembly on dock, Palmdale (STA-099) References: 15 .

Spacecraft engaged in practical applications and uses of space technology such as weather or communication (US Cat C). References: 1 , 2 , 5 , 6 .

Mass simulated SSMEs on dock, Palmdale, Enterprise (OV-101) References: 15 .

Radar calibration mission. References: 1 , 2 , 5 , 6 .

Enterprise (OV-101)/shuttle carrier aircraft mate start References: 15 .

Docked with Salyut 5. A busy, successful mission, accomplishing nearly as much as the earlier Soyuz 21's 50 day mission. Recovered February 25, 1977 9:38 GMT. Landed 37 km NE Arkalyk. References: 1 , 2 , 6 , 32 , 33 .

High resolution photo reconnaissance satellite; returned film capsule; maneuverable. References: 1 , 2 , 6 .

Continued operation of the long-range telephone and telegraph radio-communication system within the Soviet Union and transmission of USSR central television programmes to stations in the Orbita and participating international networks (international coope ration scheme). References: 1 , 2 , 5 , 6 .

Investigation of the upper atmosphere and outer space. References: 1 , 2 , 5 , 6 , 99 .

Complete Enterprise (OV-101)/shuttle carrier aircraft mated References: 15 .

Conduct first inert captive flight, Edwards (2 hours, 5 minutes), Enterprise (OV-101) References: 15 .

Tentative name before launching: MS-T3. Launching organization: Institute of Space and Aeronautical Science, University of Tokyo. Radio frequencies: 136.725 MHz, tracking; 400.500 MHz, telemetry. Active life: two weeks. Function: (1) Test of the overall p erformance of the newly developed launch vehicle, M-3H-1. (2) Experiment of magnetic stabilization. (3) Observation of ultraviolet radiation. References: 1 , 2 , 5 , 6 .

Military navigation satellite. References: 1 , 2 , 5 , 6 .

Conduct second inert captive flight, Edwards (3 hours, 13 minutes), Enterprise (OV-101) References: 15 .

High resolution photo reconnaissance mission. References: 279 .

High resolution photo reconnaissance mission. References: 42 .

Engineering test satellite. Engineering Test Satellite Type II (ETS II), Kiku 2. Launch by N launch vehicle no 3. Geographical longitude of the geostationary orbit: 130 deg E. Preliminary experiments to acquire technologies to launch,track, and control geostationary satellites. P ropagation experiment of millimetre and quasi-millimetre waves. Characteristics: Weight at launch 245 kg. Configuration: cylindrical. Height 191 cm including antenna. Diameter 141 cm. Attitude control: spin stabilization. Expected life at least 6 months. References: 1 , 2 , 5 , 6 .

Conduct third inert captive flight, Edwards (2 hours, 28 minutes), Enterprise (OV-101) References: 15 .

The Earth Return Capsule serial number 11F76-0505 was successfully recovered. During the 1990's it was auctoned off at Sotheby's for $48,875.

Conduct fourth inert captive flight, Edwards (2 hours, 11 minutes), Enterprise (OV-101) References: 15 .

Conduct fifth inert captive flight, Edwards (1 hour, 39 minutes), Enterprise (OV-101) References: 15 .

Photo surveillance; returned film capsule; maneuverable. References: 1 , 2 , 6 .

Switzerland ratified the nuclear non-proliferation treaty and ended its under-funded nuclear program.

High resolution photo reconnaissance satellite; returned film capsule; maneuverable. References: 1 , 2 , 6 .

Spacecraft engaged in practical applications and uses of space technology such as weather or communication (US Cat C). References: 1 , 2 , 5 , 6 .

KH-8 type satellite. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). References: 1 , 2 , 5 , 6 .

Area survey photo reconnaissance satellite; returned film capsule; separated science capsule. References: 1 , 2 , 6 .

Continued operation of the long-range telephone and telegraph radio-communication system within the Soviet Union and transmission of USSR central television programmes to stations in the Orbita and participating international networks (international coope ration scheme). Uncertain if Molniya-1T model was Molniya-1 or Molniya-1T. References: 1 , 2 , 5 , 6 .

Replaced Cosmos 437. Possible ELINT satellite. References: 1 , 2 , 5 , 6 .

Investigation of the upper atmosphere and outer space. References: 1 , 2 , 5 , 6 .