Posted on Feb 9, 2017
Among the unexplored mysteries of the lunar far side is a giant mound near the south pole that appears to be a volcanic structure unlike any other found on the Moon’s surface. The formation, known as Mafic Mound, stands about 800 meters (2,600 feet) tall and 75 kilometers (47 miles) across, smack in the middle of a giant impact crater known as the South Pole-Aitken Basin, largest known impact crater in the solar system, nearly 2,500 kilometers wide and 13 kilometers deep. A new study suggests that the mound is the result of a unique kind of volcanic activity set in motion by the colossal impact.
“If the scenarios that we lay out for its formation are correct, it could represent a totally new volcanic process that’s never been seen before,” said Daniel Moriarty, at Brown University’s Department of Earth, Environmental and Planetary Sciences and the study’s lead author.
“There has been no surface exploration of the far side,” Clive Neal, chair of the Lunar Exploration Analysis Group affiliated with NASA, confirmed that China’s 2018 lunar mission will be unprecedented. It is “very different to the near side because of the biggest hole in the solar system — the South Pole-Aitken basin, shown above, which may have exposed mantle materials — and the thicker lunar crust”.
The top image below is the South Pole-Aitken basin taken by the Lunar Reconnaissance Orbiter’s Wide Angle Camera.
NASA/Goddard/Arizona State University. The lower image is from the Lunar Orbiter Laser Altimeter. Mafic Mound is the reddish splotch in the middle -Red is high ground, blue is low. (NASA/Goddard/MIT/Brown University).
China aims to be the first to reach the far side of the moon. According to a white paper released in 2016, revealing plans to land a rover on the far side of the moon, a world first, as soon as 2018. The Chang’e-4 probe — named for the goddess of the moon in Chinese mythology — will be launched to the moon in 2018, the official Xinhua news agency has reported. “The Chang’e-4’s lander and rover will make a soft landing on the back side of the moon, and will carry out in-place and patrolling surveys,” according to the country’s lunar exploration chief Liu Jizhong.
The future Chang’e 4 lunar farside landing mission is rapidly taking shape. A relay orbiter will launch in 2018 for the Moon-Earth L2 point and a lander and rover will follow six months later. To the surprise of geologists in the international lunar science community, the package does not seem to include an instrument dedicated to studying the elemental chemistry of those never-before-sampled farside rocks.
The Apollo basin, the mission’s most likely target, is a large, flat double-ring impact basin on the lunar farside. A huge dark area covering much of the southern hemisphere is the south pole-Aitken basin.
New scientific payload instruments will include “a Lunar Dust Analyser (LDA) for lunar dust physical characteristics measurements, an Electric Field Analyser (EFA) to measure magnitude of electric field at different elevations, a Plasma and Magnetic Field Observation Package (PMFOP), a Lunar Seismometer (LS) for lunar internal structure and impact investigations, [and] a VLF Radio Interferometer (VRI) for radio astronomical observation.”
There will also be a neutron dosimeter to take measurements relevant to future human exploration, to be contributed by Germany for the lander. According to the Kiel University press release, the dosimeter is a thermal neutron spectrometer and therefore could measure water content of the regolith beneath the lander.
The rover will carry three of the four Yutu instruments, including panoramic camera, ground-penetrating radar, and an infrared spectrometer. It will, however, not carry an alpha-particle X-ray spectrometer.
New instruments include “an Active Source Hammer (ASH) for active source seismic experiments, and a second VLF Radio Receiver (VRR).” There will also be an energetic neutral atom analyzer, to be contributed by Sweden for the rover.
Lunar geologists worldwide have been pushing for a landing on the lunar farside — and, even better, sample return — for a long time. Much of the farside is covered by a feature called the South Pole-Aitken Basin. It is an enormous impact basin, stretching between the south pole and Aitken crater, that is the oldest discernible feature on the Moon and among the largest impact basins in the whole solar system.
Analysis of data from orbital missions suggests that its rocks are unique and have likely not been sampled by any previous lunar landing. The rocks may have a unique composition because they have sampled lunar mantle, or because they represent the composition of what would have been an enormous sheet of impact melt, or some other reason.
Chang’e 4’s robust science package has more of a physics focus than a geochemistry focus. It may have a seismology station with a mobile roving hammer, and ground-penetrating radar to look at the subsurface, and several instruments focused on the farside space environment, taking advantage of the bulk of the Moon to shield its sensitive radio instruments from radio frequency interference from Earth. Hopefully Chang’e 4 can set a precedent for farside lunar landings.
The moon’s far hemisphere is never directly visible from Earth and while it has been photographed, with the first images appearing in 1959, it has never been explored. Earlier reports from the Xinhua news agency hinted that China may be considering the construction of a pioneering radio telescope on the moons virgin far side, which will give it an unobstructed window on the Cosmos that was confirmed June, 2016 when an agreement was announced between the Netherlands and China, that a Dutch-built radio antenna will travel to the Moon aboard the Chinese Chang’e 4 satellite and usher in a new era of radio astronomy allowing for the study of objects that might otherwise be invisible or hidden in other parts of the electromagnetic spectrum.
“Radio astronomers study the universe using radio waves, light coming from stars and planets, for example, which is not visible with the naked eye,” commented Heino Falke – a professor of Astroparticle Physics and Radio Astronomy at Radboud University. “We can receive almost all celestial radio wave frequencies here on Earth. We cannot detect radio waves below 30 MHz, however, as these are blocked by our atmosphere. It is these frequencies in particular that contain information about the early universe, which is why we want to measure them.”
Beijing sees its military-run, multi-billion-dollar space program as a marker of its rising global stature and mounting technical expertise, as well as evidence of the ruling Communist Party’s success in transforming the once poverty-stricken nation.
But for the most part it has so far replicated activities that the US and Soviet Union pioneered decades ago. “The implementation of the Chang’e-4 mission has helped our country make the leap from following to leading in the field of lunar exploration,” Liu added.
In 2013, China landed a rover dubbed Yutu on the moon and the following year an unmanned probe completed its first return mission to the earth’s only natural satellite. Beijing has plans for a permanent orbiting station by 2020 and eventually to send a human to the moon.
Space flight is “an important manifestation of overall national strength”, Xinhua cited science official Qian Yan as saying, adding that every success had “greatly stimulated the public’s… pride in the achievements of the motherland’s development.”
The Daily Galaxy via NASA, planetary.org, Beijing (AFP), agu.org, Xinhua News Agency, and the The Harvard Gazette