Lunar exploration continues to expand everyday, from small private-sector contracts to new missions developing spacecrafts and robotic platforms to study the surface of the Moon. Recently, humanity took another step forward to returning humans to the Moon and learning more about its late geologic history. On November 24th, 4:30 am CST, the Chinese National Space Administration (CNSA) started the third stage of its lunar exploration mission and launched its fifth Chang'e mission to the Moon. The CNSA launched Chang'e 5 on a Long March 5 rocket system from the Wenchang Space Launch Center in the Hainan Province. The aim of the mission is to return pristine lunar samples from the Mons Rumker volcanic complex in the Oceanus Procellarum region on the lunar nearside. If all goes according to plan, Chang'e 5 will be the latest robotic mission to have returned lunar samples since the 1970s.
Video Credit: DW News
The last time lunar samples were returned to Earth for analysis was from the Soviet Union mission Luna 24, a lander and rover mission sent to sample regolith on the lunar nearside. Chang'e 5, will be collecting samples that will arguably be the youngest lunar rocks ever returned. The Apollo and Luna missions brought back some of the earliest dated material on the Moon, providing us with unprecedented information and data about the processes that occurred during the formation of the solar system and the early Earth-Moon system. Gaps in our research were events and geologic processes that have occurred during the last 1-2 billion years. This time period is within the timeframe when multi-cellular life arose on Earth, so understanding what occurred on the Moon during this time will help us better understand how the surface of the Earth evolved 1-2 billion years ago.
Chang'e 5 Spacecraft and Mission Timeline
The Chang'e 5 mission comprises four spacecraft components: a lunar orbiter, re-entry capsule, a lander, and an ascent vehicle. The spacecraft weighs ~18,100 lbs (~8,200 kg) and is planned to enter lunar orbit around the 28th of November. Once the spacecraft has entered lunar orbit, the lander and ascent vehicle will be released from the orbiter and descend down to the Mons Rumker volcanic complex on the lunar surface. Using solar system, the lander will measure its surrounding environment using a variety of high-resolution cameras, a ground-penetrating radar and a spectrometer. The cameras will image the surrounding terrain to provide new geologic context of Mons Rumker's surface and take before and after images of sample sites. The ground-penetrating radar will map the subsurface of the volcanic deposit, detecting and mapping lava flow surfaces and determine the depth of the lunar regolith. The spectrometer will analyze the mineral composition of the regolith and drill core samples and calculate how much water is locked in the lunar soil.
Graphics of the launch system, Chang'e 5 spacecraft and lander drill core sampling system. Credit: Planetary Society.
The lander can only operate during a lunar day and therefore, must complete its analysis and sample collection, deposit the samples into the ascent vehicle and launch it before lunar night falls over the study site. As a note, one lunar day is ~14 Earth days so this part of the mission only has a two week window, which is small for space exploration. The science team will need to be make fast decisions on what samples to return to Earth for further analysis. The ascent vehicle will rendezvous with the orbiter and attach itself to the re-entry vehicle. Afterwards, the orbiter will adjust its orbit on a return path back to Earth. The orbiter will release the re-entry vehicle just before it reaches Earth. The re-entry vehicle will not enter Earth's atmosphere the same way service modules re-enter from low-Earth orbit. Orbiters and modules returning from the Moon travel 3 km/s faster than low-Earth orbit. The Chang'e 5 re-entry vehicle will re-enter Earth's atmosphere by performing a "skip re-entry" method, bouncing off the atmosphere once to slow down the vehicle before descending down to the Earth's surface. The re-entry vehicle is planned to touchdown at a landing site in Inner Mongolia.
Illustration of the "Skip Re-entry" method. Spacecraft returning from the Moon will going through a first-entry and bounce off the atmosphere, decelerating its speed. The spacecraft skips over the atmosphere and reenters before landing back onto the surface of the Earth. Credit: ChinaDaily Asia site.
Why Mons Rumker?
The CNSA selected Mons Rumker as the landing site for Chang'e 5 because it contains lunar rocks with geologic ages around 1.21 billions years. Mons Rumker is a volcanic complex that is 70 km in diameter and has strong spectroscopic signatures of basaltic lunar mare material. It is centered at 301.9°E, 40.7°N and comprises a plateau with an area of ~4000 km². Smith (1974) identified over 30 volcanic domes, classifying them into three categories based off shape, diameter and stratigraphic relationship. Radar studies of the Mons Rumker interpret that the surface is covered in a rock-poor, fine-grained regolith deposit (Campbell et al., 2009). This returned moderate radar scatter signatures that reflect the surfaces of volcanic domes and lava flows beneath the fine-grained regolith cover. The domes are believed to have formed during low effusion volcanic eruptions, with magma fed by a dike situated at the base or beneath the lunar crust (Wöhler et al., 2007). The geologic history and volcanic activity of this region of the Moon is still poorly understood, and until 2017 (Zhao et al., 2017), no systematic study had been conducted on Mons Rumker. The lack of information about the geologic history of Mons Rumker and its surrounding region, and potential sampling of young lunar samples made this location the official landing site for Chang'e 5.
Location of the Mons Rumker volcanic complex in Oceanus Procellarum on the Moon. The background image is from the United States Geological Survey lunar airbrushed shaded relief map. Map is in a simple cylindrical projection (https://webgis.wr.usgs.gov/pigwad/down/moon_airbrushed_shadedrelief_warp.htm). The red box is the boundaries of the Mons Rumker image below.
An image of the Mons Rumker volcanic complex taken by the Lunar Reconnaissance Orbiter Wide-Angle Camera. The background image is a global morphology mosaic with a resolution of 100 m/pixel (https://astrogeology.usgs.gov/search/map/Moon/LRO/LROC_WAC/Lunar_LRO_LROC-WAC_Mosaic_global_100m_June2013)
If you want to find more information about the Chang'e 5 mission, you can visit these websites:
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References
Campbell, B. A., B. R. Hawke, and D. B. Campbell (2009), Surface morphology of domes in the Marius Hills and Mons Rümker regions of the Moon from Earth‐based radar data, J. Geophys. Res., 114, E01001, doi:10.1029/2008JE003253.
Smith, E. I. (1974), Rümker Hills: A lunar volcanic dome complex, Moon, 10(2), 175– 181, doi:10.1007/BF00655718.
Wöhler, C., R. Lena, and K. C. Pau (2007a), The lunar dome complex Mons Rümker: Morphometry, rheology, and mode of emplacement, Lunar Planet. Sci., Abstract 1091.
Zhao, J., Xiao, L., Qiao, L., Glotch, T. D., & Huang, Q. (2017). The Mons Rümker volcanic complex of the Moon: A candidate landing site for the Chang'E‐5 mission. Journal of Geophysical Research: Planets, 122(7), 1419-1442. https://doi.org/10.1002/2016JE005247
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