Chinese scientists are in the course of developing a recoverable lunar robotic spacecraft Chang'e 5 that is to reach the Moon by 2017 with a mission to deliver samples of rock and soil back to Earth, according to Space Industry News.

"The development of Chang'e 5 is proceeding smoothly," a China State Administration of Science, Technology and Industry spokesman Wu Zhijian was cited as saying by an online media publication China Topix.

The creation of Chang'e 5 is part of the Chinese Lunar Exploration Program also known as the Chang'e program created by the country's National Space Administration, which is divided into three operational phases.

First phase covered orbital missions with the first and second lunar orbiters of the series successfully completing their respective missions.

Second phase concentrates on soft landers and rovers and has not yet been completed. Chang'e 3, carrying a lunar rover designed to explore and map the Moon's surface in a three-month mission, successfully landed on the natural satellite in December, 2013.

Within the framework of the program, a younger generation test vehicle, Chang'e 4, is scheduled to take off later this year to pave the way for the third phase sample-return mission. The lunar test orbiter has already arrived at the Xichang launch site in the southwestern province of Sichuan in China.

Its initial purpose was to back-up the Chang'e 3, however, because of the third mission's success, the configuration of the orbiter changed to testing new equipment including its abilities in flight sequence control, allowing scientists to perfect orbit design of lunar vehicles, and practicing to keep the unmanned spacecraft orbitally stable.

"Scientists believe we need to launch the spacecraft to prove that our current technical plan can actually bring Chang'e 5 home safely," Chief Designer of the Chang'e 5, Hu Hao was cited as saying by Space Industry News.

Upon returning to Earth with lunar rock and soil samples, the Chang'e 5 will be falling through the planet's atmosphere at an escape velocity of 11.2 kilometers per second. China's spacecraft have never before re-entered the atmosphere at such high speeds and, according to Hu, no simulation test is able to recreate such an event. "The re-entry speed means the return capsule could overheat or prove difficult to track and control," Hu said.

Phase three is aimed at lunar sample return missions, with the Chang'e 5 comprising of the second generation orbiter base structure, a lander, an ascender and a returner.

The lander will carry equipment enabling it to preform soft landings as well as to collect lunar rock and soil samples from as deep as 2 meters below the Moon surface. The explorer is set to return to Earth before 2020, according to China Daily.

"The program's third phase will be more difficult because many breakthroughs must be made in key technologies, such as moon surface takeoff, sampling encapsulation, rendezvous and docking in lunar orbit, and high-speed Earth re-entry," China Topix cited Zhijian.