China on Monday published photos of the Earth and Moon together taken by the orbiting service module of the country's returned unmanned lunar orbiter.
The photos were taken Sunday by the service module at a point 540,000 km from Earth and 920,000 km from the Moon after it was separated from the return capsule of China's test lunar orbiter on Nov. 1, ending its eight-day mission.
It was the world's first mission to the Moon and back in some 40 years, with China becoming the third nation to do so after the Soviet Union and the United States.
The service module went back into orbit and conducted more tests after the Nov. 1 separation about 5,000 km above Earth, said a statement from China's State Administration of Science, Technology and Industry for National Defense, which released the photos.
Launched Oct. 24, the orbiter traversed 840,000 km in eight days in a mission that saw it go around the far side of the Moon. One of the biggest challenges was a "bounce" during the orbiter's re-entry as it made its way home, as the orbiter must enter the atmosphere at a very precise angle. An error of 0.2 degrees would have rendered the mission a failure.
To help it slow down, the craft is designed to "bounce" off the edge of the atmosphere before re-entering again. The process has been compared to a stone skipping across water, and can shorten the "braking distance" for the orbiter, according to Zhou Jianliang, chief engineer with the Beijing Aerospace Command and Control Center.
The program is a test run for the final chapter of the country's three-step lunar program, which includes orbiting, landing and returning.
The latest mission is to obtain data and validate re-entry technology such as the heat shield and trajectory design for a future landing on the Moon as part of the Chang'e-5 mission, expected to be launched around 2017 to collect lunar samples and return to Earth. If successful, China will become the third nation to do so.