At the very top of the satellite, a package of science instruments designed to register ultraviolet and x-ray radiation was mounted. Inside the SP-65 instrument, three photo multiplier cells spaced at 120 degrees from each other were designed to register solar radiation. Lyman alpha (1216 angstrom units) and X-ray segments of the solar spectrum would be isolated by optical filters. Varying intensity of solar radiation would be derived as electrical energy from the photo-multiplier tube, amplified and downlinked to the ground. (148)
A special truss structure held main elements of Sputnik-2 together. A payload fairing protected the satellite during the launch and it would be jettisoned at the end of the powered flight, apparently leaving it in orbit along with the satellite.
A special timer was installed onboard the satellite with the task of turning on the scientific payload when spacecraft overflew the Soviet ground control stations and turning it off again, as the satellite went out of range. (248) The main purpose of this feature was to conserve onboard power supply, although secrecy was also a consideration. (262)
Sputnik-2's Tral telemetry system was configured to transmit following information to the ground:
Intensity of solar radiation in various ranges of electromagnetic spectrum;
Variation of intensity of space radiation;
Movements of the dog relative to its tray;
Frequency of dog breath;
Dog's cardiovascular pressure;
Temperature data from 12 locations around the satellite;
In addition, some sources claim, the dog cabin was equipped with a slow-scan TV camera, capable of transmitting 10 frames per second with 100 lines per frame. The imagery was channeled via the Tral telemetry system, using its frequency. (262) However according to the developer of the television system, it was not ready until first test launches of the Vostok spacecraft.
According to the flight program, the satellite was to enter orbit with the altitude of a perigee (lowest point) 223 kilometers above the Earth surface and apogee (highest point) 945-1,555 kilometers.
The scientific equipment was designed to transmit data for at least seven days. (A secret note No. SK-3/2468 to the Central Committee promised operations of payloads during 5-7 days.) After radio transmitters onboard would stop working, ground control hoped to use optical and radar systems for further tracking of the satellite.
The mass of the Sputnik-2 reached 508.3 kilograms, however including the empty core stage of the launch vehicle, it remained attached to, the total mass of the orbiting vehicle was 7.79 tons. (248)
Modifying the rocket
A number of modifications were introduced to the launch vehicle, intended to carry Sputnik-2 into orbit. Last but not least, a number of steps were made on the ground to prepare for tracking the second satellite in orbit and capturing its scientific data.