The Ye-8-5 was a variant of the basic Ye-8 lunar rover spacecraft developed by the Lavochkin design bureau. This particular version, whose development began in 1968, was designed to recover a small portion of soil from the lunar surface and return it to Earth.
It shared the basic lander stage (KT) as the rover variant (built around a structure comprising four spherical propellant tanks linked together in a square), which was now installed with a robot arm to scoop up lunar soil. The rover was replaced by a new ascent stage that was built around three spherical propellant tanks that consisted of a main rocket engine (the S5.61) to lift off from the Moon, a pressurized compartment for electronics, and a small 86-pound (39-kilogram) spherical capsule which would detach from the stage and reenter Earth’s atmosphere with its valuable payload of lunar dust.
On the first launch attempt of the Ye-8-5 robot scooper, the first three stages of the Proton worked without fault, but the Blok D fourth stage, which was to fire to attain orbital velocity, failed to ignite due to a disruption in the circuit of its guidance system. The payload reentered over the Pacific Ocean without reaching Earth orbit.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.