Samplers, rovers and orbiters
When Luna 15 was smashed to pieces in the Sea of Crises in July 1969, Russia’s plan to upstage Apollo by the first automatic recovery of lunar soil came unstuck. But the Soviet Union permitted the programme to continue, for two reasons: first, because the series could produce a credible automatic programme for the exploration of the moon; and, second, because the series was important if the Soviet man-on-the-moon programme were to be completed after all. Such hopes still existed in reality up to the summer of 1974 and on paper for another two years.
Luna 15 was the first of the Ye-8-5 soil sampler missions to leave the Earth, one earlier mission having failed on launch. Some considerable work was still required for such a mission to be successful. A number of lessons had arisen from the troubled experience of Luna 15. There had been considerable difficulties controlling the craft. Luna 15’s original orbit had been far from that intended. The radar had presented problems. Despite delaying the final landing manoeuvre, the final burn had not proved to be sufficiently precise. In the months that followed the loss of Luna 15, the Lavochkin engineers made the adjustments that they felt sure could guarantee success the next time.
The Lavochkin engineers were convinced that the basic design was sound. Although the three missions had been launched hastily, the basic Ye-8 design, originally intended for lunar rovers, had a lengthy and careful design over many earlier years. The sample return spacecraft consisted of three parts: a descent stage, ascent stage and return cabin.
Ye-8-5 lunar sample return spacecraft
Height 3.96 m
Weight on launch 5,750 kg
on moon 1,880 kg
KT descent stage
For radio communications, the lander carried a cone-shaped antenna on a long boom, working on 922 MHz and 768 MHz. Uplink was received on 115 MHz. A dish-shaped radar was located on the bottom of the spacecraft.
The Lavochkin bureau still had another three sample return spacecraft available. All were duly launched in the period following the Apollo 11 landing, on 23rd September 1969 (Cosmos 300), 22nd October 1969 (Cosmos 305) and 6th February 1970. On Cosmos 300, there was a leak in the oxidizer tank of block D, which depleted the entire supply during Earth orbit injection and could not fire out to the moon, leaving the spacecraft to crash back to Earth four days later. On Cosmos 305, the attitude control system failed and block D did not get into the right attitude to fire to the moon, crashing back near Australia. With the February 1970 launching, Proton’s first-stage engines were erroneously turned off at 127 sec and it cratered downrange.
Of the first five attempts, only one had left Earth orbit. A second batch of sample return spacecraft was now constructed and there was a delay until the first of the new spacecraft could be available. In the meantime, concerted efforts were applied to attempt to fix the appalling record of the Proton rocket. Proton’s unreliability had not only cost the moon programme dearly, but dogged the interplanetary programme, destroying two of a new series of Mars probes in March 1969. Eventually, Georgi Babakin persuaded the minister responsible for the space programme, Sergei Afanasayev, to introduce a requalification programme. This took place over spring and summer 1970, culminating in a suborbital test on 18th August 1970. This led to a swift and radical improvement in performance, but Soviet space histories might have been happier, had these changes been introduced sooner.