♪ Oh Venus ♫
The Soviet probe Venera 4 is successfully launched. On October 18, 1967, it will enter Venus’ atmosphere where it will become the first space probe to successfully return atmospheric data from another planet
Venera 4 (Russian: Венера-4 meaning Venus 14), was a probe in the Soviet Venera program for the exploration of Venus. It was the first successful probe to perform in-place analysis of the environment of another planet. It may also have been the first probe to land on another planet, with the fate of its predecessor Venera 3 being unclear.
Venera 4 provided the first chemical analysis of the Venusian atmosphere, showing it to be primarily carbon dioxide with a few percent of nitrogen and below one percent of oxygen and water vapors. The station detected a weak magnetic field and no radiation field. The outer atmospheric layer contained very little hydrogen and no atomic oxygen. The probe sent the first direct measurements proving that Venus was extremely hot, that the atmosphere was far denser than expected, and that Venus had lost most of its water long ago.
The mission was considered a complete success, especially given several previous failures of Venera probes. The first successful landing on Venus was achieved by Venera 7 in 1970.
The main hub of Venera 4 stood 3.5 meters high, its solar panels spanned 4 meters and had an area of 2.5 m². The hub included a 2 meter long magnetometer, an ion detector, a cosmic ray detector and an ultraviolet spectrometer capable of detecting hydrogen and oxygen gases.
The devices were intended to operate until entry into the Venusian atmosphere. At that juncture, the station was designed to release the probe capsule and disintegrate. The rear part of the hub contained a liquid-fuel thruster capable of correcting the flight course. The flight program was planned to include two significant course corrections, for which purpose the station could receive and execute up to 127 different commands sent from the Earth.
The front part of the hub contained a nearly spherical landing capsule 1 meter in diameter and weighing 383 kg. Compared to previous (failed) Venera probes, the capsule contained an improved heat shield which could withstand temperatures up to 11000 °C. Instead of the previous liquid-based cooling design, a simpler and more reliable gas system was installed.
The capsule could float in case of a water landing. Considering the possibility of such a landing, its designers made the lock of the capsule using sugar; it was meant to dissolve in liquid water, releasing the transmitter antennas. The capsule contained a newly developed vibration-damping system and its parachute could resist temperatures up to 450 °C.
The capsule contained an altimeter, thermal control, a parachute and equipment for making atmospheric measurements. The latter included a thermometer, barometer, hydrometer, altimeter and a set of gas analysis instruments. The data were sent by two transmitters at a frequency of 922 MHz and a rate of 1 bit/s; the measurements were sent every 48 seconds. The transmitters were activated by the parachute deployment as soon as the outside pressure increased to 0.6 atmospheres, which was thought to occur at the altitude about 26 km above the surface of Venus. The signals were received by several stations, including the Jodrell Bank Observatory.
The capsule was equipped with a rechargeable battery with a capacity sufficient for 100 minutes of powering the measurement and transmitter systems. To avoid becoming discharged during the flight to Venus, the battery was recharged using the solar panels of the hub. Before the launch, the entire Venera 4 station was sterilized to prevent possible biological contamination of Venus.
Ten probes from the Venera series successfully landed on Venus and transmitted data from the surface, including the two Vega program and Venera-Halley probes. In addition, thirteen Venera probes successfully transmitted data from the atmosphere of Venus.
Among the other results, probes of the series became the first man-made devices to enter the atmosphere of another planet (Venera 4 on October 18, 1967), to make a soft landing on another planet (Venera 7 on December 15, 1970), to return images from the planetary surface (Venera 9 on June 8, 1975), and to perform high-resolution radar mapping studies of Venus (Venera 15 on June 2, 1983).
So, the entire series could be considered highly successful. Unfortunately the surface conditions on Venus are extreme, which meant that the probes only survived on the surface for a duration of 23 minutes (initial probes) up to about two hours (final probes).
Pictures from Venus from later Venera Missions
For My Sis