Chang'e 5

Chang'e 5 is a robotic mission of the Chinese Lunar Exploration Program. Like its predecessors, the spacecraft was named after the Chinese moon goddess, Chang'e. It was launched on 23 November 2020 at 20:30 UTC from Wenchang Spacecraft Launch Site on Hainan Island and landed on the Moon on 1 December 2020, followed by returning to Earth with lunar samples on 16 December 2020, at 17:59 UTC.

Chang'e 5 was China's first sample return mission, which aimed to return at least 2 kilograms (4.4 pounds) of lunar soil and rock samples back to Earth and the first lunar sample-return mission since Luna 24 in 1976. By completing the mission, China became the third country to successfully obtain samples returned from the Moon after the United States and the Soviet Union.

Overview
The Chinese Lunar Exploration Program is designed to be conducted in four phases of incremental technological advancement: The program aims to facilitate a crewed lunar landing in the 2030s and possibly build an outpost near the lunar south pole.
 * 1) The first was simply reaching lunar orbit, a task completed by Chang'e 1 in 2007 and Chang'e 2 in 2010.
 * 2) The second is landing and roving on the moon, as Chang'e 3 did in 2013 and Chang'e 4 in 2019 (launched in December 2018, landed on the far side of the Moon in January 2019).
 * 3) The third phase is collecting lunar samples from the near side and sending them to Earth, a task for the Chang'e 5 and the future Chang'e 6 missions.
 * 4) The fourth phase consists of the development of a robotic research station near the Moon's south pole.

Components
The mission consists of four modules or components: The estimated launch mass is 8200 kg, the lander is projected to be 1200 kg and the ascent vehicle is about 500 kg.
 * The lander collected about 2 kg of samples from 2 m below the surface and placed them in an attached ascender that was launched into lunar orbit on 3 December 2020.
 * The ascender made an automatic ascent, rendezvous and, docking with an orbiter that then transferred the samples into a sample-return capsule for their delivery to Earth.
 * The orbiter began the roughly 4.5-day trip back to Earth and released the reentry capsule just before arrival. The reentry capsule performed a skip reentry to bounce off the atmosphere once before reentering.
 * The returner received samples from the ascender and brought them back to the Earth.

Unlike Chang'e 4 which was equipped with a radioisotope heater unit to survive the extreme cold of lunar night, the Chang'e 5 landing and sampling needed to take place within a single, 14-Earth-day lunar daytime. The total mission lasted a total of 23 days until landing in Dorbod Banner, Inner Mongolia, on 16 December 2020. Samples were transferred to specially developed facilities for handling, analyzing, and storing the lunar material.

Lander science payload
The lander carries landing cameras, a panoramic camera, a spectrometer to determine mineral composition, a soil gas analytical instrument, a soil composition analytical instrument, a sampling sectional thermo-detector, and a ground-penetrating radar.

For acquiring samples, it is equipped with a robotic arm, a rotary-percussive drill, a scoop for sampling, and separation tubes to isolate individual samples.

Mission profile
The Chang'e 5 consists of a service module, lunar lander, ascender, and a sample-return vehicle. This probe was planned to be launched in November 2017 by a Long March 5 rocket from the Wenchang Satellite Launch Center on Hainan Island; however, a July 2017 failure of the referenced carrier rocket forced a delay to the original schedule. On 27 December 2019, the Long March 5 successfully returned to flight operations, thereby allowing the current mission to proceed.

Launch
The Chang'e 5 probe was launched on 23 November 2020 at 20:30 UTC, by a Long March 5 rocket from the Wenchang Satellite Launch Center on Hainan Island. Sunrise over Mons Rümker occurred on 27 November 2020, ahead of the landing.

Selenocentric phase
On 28 November 2020 at 12:58 UTC, the probe fired its engine for 17 minutes and braked into orbit around the Moon at an altitude of 400 km. On the morning of 30 November 2020, the lander, with the ascender, separated from the lunar orbiter in preparation for landing.

Landing site
The lander and ascender landed on the Moon on 1 December 2020 at 15:11 UTC. The mission's landing zone is near Mons Rümker in Oceanus Procellarum (Ocean of Storms), located in the northwest region of the Moon's near side. This area contains geological units around 1.21 billion years old, compared to the Apollo samples that were between 3.1 and 4.4 billion years old. The location is a large, elevated volcanic mound 70 km in diameter that features a strong spectroscopic signature of basaltic lunar mare material. It is hoped that the young age of the samples collected will allow scientists to improve calibration techniques for estimating the ages of geological surfaces on planets, moons and asteroids throughout the Solar System.

Return of samples to Earth
On 3 December 2020, the Chang'e 5 ascender lifted off from Oceanus Procellarum at 15:10 UTC and, six minutes later, achieved lunar orbit. The ascender docked with the orbiter–returner combination in lunar orbit on 5 December 2020 at 21:42 UTC, and the samples were transferred to the return capsule at 22:12 UTC. Undocking of the ascender from the orbiter–returner combination took place on 6 December 2020 at 04:35 UTC. After completing its role in the mission, the ascender was commanded to deorbit on 7 December 2020, at 22:59 UTC, and crashed into the Moon's surface at 23:30 UTC, in the area of (~30°S, 0°E). On 13 December 2020 at 01:51 UTC, from a distance of 230 kilometers from the lunar surface, the orbiter and returner successfully fired four engines to enter the moon-Earth Hohmann transfer orbit.

The electronics and systems on the Chang'e 5 lunar lander were expected to cease working on 11 December 2020, due to the Moon's extreme cold and lack of a radioisotope heater unit. However, engineers expected the Chang'e 5 lander to be damaged and stop working after acting as the launchpad for the ascender module on 3 December.

On 16 December 2020 at around 18:00 UTC, the roughly 300-kilogram return capsule performed a ballistic skip reentry, in effect bouncing off the atmosphere over the Arabian Sea before re-entry. The capsule, containing around 2 kilograms of drilled and scooped lunar material, landed in the grasslands of Siziwang (Dorbod) Banner in the Ulanqab region of south central Inner Mongolia. Recovery vehicles located the capsule shortly afterwards.

Lunar sample research
Verifying the age of the samples would provide data on the hypothesis that some areas of the Moon experienced late-stage volcanism, and compositional analysis could provide insights into the reasons behind it. Katherine Joy of the University of Manchester considers that the samples might represent some of the last lunar lava flows to have erupted. "If so, they not only tell us about the Moon's thermal history but these are also vital samples to help us calibrate the Moon's impact history." Dating this relatively young part of the Moon's surface would provide an additional calibration point for estimating the surface ages of other Solar System bodies. Wu Yanhua (吴艳华), deputy director of the China National Space Administration (CNSA) announced that the new samples will be shared with the UN and international partners for space research purposes.

Chang'e 5-T1
Chang'e 5-T1 is an experimental robotic lunar mission that was launched on 23 October 2014 to conduct atmospheric re-entry tests on the capsule design that was planned to be used in the Chang'e 5 mission. Its service module, called DFH-3A, remained in orbit around the Earth before being relocated via Earth–Moon L2 to lunar orbit by 13 January 2015, where it is using its remaining 800 kg of fuel to test maneuvers critical to future lunar missions.

International collaboration
The European Space Agency (ESA) has supported the Chang'e 5 mission by providing tracking via ESA's Kourou station, located in French Guiana. ESA has tracked the spacecraft during the launch and landing phases while providing on-call backup for China's ground stations throughout the mission. Data from the Kourou station has helped the mission control team at the Beijing Aerospace Control Centre to determine the spacecraft's health and orbit status. Chang'e 5 was returned to Earth on 16 December 2020. During the landing phase, ESA used its Maspalomas Station, located in the Canary Islands and operated by the Instituto Nacional de Técnica Aeroespacial (INTA) in Spain, to support the tracking efforts.

International reactions
Science journalist Bob McDonald discussed Chang'e 5 in comparison to the Soviet Luna program, which involved Luna 15, Luna 16, and Luna 24 being sent to the Moon. Luna 15 attempted to grab a sample of lunar soil and return it to Earth before the American Apollo 11 astronauts Neil Armstrong and Buzz Aldrin got back in July 1969. It crashed during its landing attempt, hence losing the opportunity for a "propaganda coup". The Luna 16 mission successfully returned about 100 grams of lunar soil a year later and two other sample return missions succeeded in subsequent years, the most recent being Luna 24 in 1976. McDonald considers that China has entered another Moon race.

Bradley Perrett, Asia-Pacific Bureau Chief of Aviation Week Network, opined that the Moon race between the Soviet Union and the United States in the 1960s was driven by propaganda: a message to the world about their strength. Perrett noted that the Chang'e project was also driven by propaganda utility, but primarily for the internal audience – the reason that the Chinese government funded this mission was to show the Chinese people that "the Chinese can do it".

Simon Sharwood, APAC Editor of The Register, observed that the mission was a success that went off without a hitch, with even the damage to the lander when the ascender lifted off not unexpected. Sharwood said that Chinese youths already have a lot to aspire given that China plans to build a space station and moon base in the future, but "such opportunities will only be possible if their social credit score... marks them out as suitable for such honors".