Yesterday, crowds gathered around the Wenchang Spacecraft Launch Site to witness the liftoff of the Long March 5B rocket carrying the Chang’e-6 mission.
On May 3rd at 5:27 PM, the Chang’e-6 probe was successfully launched by the Long March 5B rocket from China’s Wenchang Spacecraft Launch Site. It precisely entered a translunar orbit, embarking on humanity’s first mission to ‘treasure-hunt’ on the far side of the Moon. Approximately 37 minutes into its flight, the probe separated from the rocket and was directed into its predetermined translunar orbit, with a perigee of 200 kilometers and an apogee of about 380,000 kilometers from Earth.
This mission is notable for its long duration and numerous engineering innovations.
The Chang’e-6 probe is composed of an orbiter, a reentry capsule, a lander, and an ascender. Supported by ground-based controls and the Queqiao No. 2 relay satellite, the probe will go through stages including translunar injection, lunar orbit insertion, and soft landing on the moon’s surface. Once on the far side of the Moon, the planned tasks include collecting lunar rock and soil samples and conducting scientific surveys. After the sampling is completed, the ascender will take off from the lunar surface and transfer the samples to the orbiter in lunar orbit; the reentry capsule will then travel back to Earth, reenter the Earth’s atmosphere at velocities close to the second cosmic velocity, and return the precious lunar samples to our planet.
In 2004, China officially approved the Lunar Exploration Project, led by the National Space Administration. Over the past 20 years, China has steadily advanced its lunar exploration from capturing a full-moon image with Chang’e-1, achieving humanity’s first soft landing on the far side of the Moon with Chang’e-4, bringing back lunar samples with Chang’e-5, and now successfully launching Chang’e-6.
To date, all of humanity’s lunar sample return missions have been to the near side of the Moon. The landing site preliminarily chosen for Chang’e-6 is the South Pole-Aitken basin, one of the Moon’s three largest geophysical features with high scientific research value.
The Chang’e-6 mission is expected to last approximately 53 days. Compared to the Chang’e-5, which conducted a sample-return mission from the near side of the Moon in 2020, the current mission is longer, possesses more engineering innovations, holds greater risk, and is more challenging. It necessitates breakthroughs in areas such as cislunar retrograde orbit design and control, rapid and intelligent lunar sampling, and ascension from the lunar surface. The precious lunar samples Chang’e-6 will collect are likely to deepen our understanding of the Moon’s origins and its evolutionary history.
Chang’e-6 also carries four international payloads, including instruments from the European Space Agency (ESA), France, Italy, and Pakistan, for conducting simultaneous research on the far side of the Moon.
Traveling 380,000 Kilometers to the Moon’s Far Side: How?
The Moon lies approximately 380,000 kilometers from Earth, always showing the same face to our planet. The journey to the far side to ‘treasure-hunt’ is unprecedented!
To reach the far side, Chang’e-6 first had to enter a translunar orbit, with a perigee of 200 kilometers and an apogee of about 380,000 kilometers, from Earth. Weighing 100 kilograms more than Chang’e-5, it required the most experienced and capable “escort,” the Long March 5 rocket. After numerous design optimizations and process improvements, the veteran rocket was successfully “slimmed down” to meet the needs of the “passenger.”
“If the launch time window is missed, the mission to the Moon could be impacted,” explained Li Pingqi from the China Aerospace Science and Technology Corporation First Academy. Researchers applied “narrow window multi-trajectory” launch technology to design ten trajectories to the Moon within the two-day launch window, each lasting 50 minutes per day, to improve the probability and reliability of the launch.
To reach and operate on the far side of the Moon, communication issues also had to be addressed. The massive bulk of the Moon would block signals from Chang’e-6 to Earth-based command centers, which is where the Queqiao No. 2 relay satellite comes in, acting as an “ear to the wind” and building a “communication bridge.”
Completing the 53-Day Cosmic Express Delivery:
The whole journey of Chang’e-6’s “business trip”