To figure out what secrets the moon may still be hiding, scientists are excited to get their hands on new rock samples. The Change-5 sample return mission \u201cno doubt will have additional rock types that we havent sampled yet,\u201d says planetary scientist David Blewett of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. \u201cIf you came to the Earth and landed in Great Britain and made all your conclusions about the Earth from what you saw \u2026 you really wouldnt have the whole picture.\u201d<\/p>\n
Journey to the dark side[hhmc]
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The Change-4 spacecraft includes a lander and a rover that were originally built as backups for the 2013 Change-3 mission, which marked Chinas first moon landing<\/a> \u2014 and the first moon landing at all since the 1970s (SN Online: 12\/16\/13). The uncrewed Change-3 lander-rover duo touched down in a vast lava plain in the north known as Mare Imbrium, where the craft measured the composition and thickness of the lunar soil and discovered what might be a new type of basalt, or lava-based rock<\/a>.<\/p>\n This time, China has its sights set on lunar regions never before explored. Change-4 is aiming for the moons largest, deepest and possibly oldest known feature created by an impact, the South Pole\u2013Aitken basin, on the lunar farside, which always faces away from Earth. The whole basin, which is 2,500 kilometers wide and up to 8.2 kilometers deep, is too big for the rover to explore. So Change-4 is shooting for the 186-kilometer-wide Von K\u00e1rm\u00e1n crater within the larger basin for a cosmic hole in one.<\/p>\n The enormous impact that formed the South Pole\u2013Aitken basin is thought to have excavated parts of the lunar mantle, the once-molten layer of denser rock that sits below the crust. Exploring the crater could offer a window into the moons interior.<\/p>\n \u201cTheres a big argument about the composition of the lunar mantle,\u201d Xiao says. For instance, is the mantle \u201cwet\u201d<\/a> and full of hydrated minerals, or dry? If it is wet, how did water survive the colossal impact thought to have formed the moon? Change-4 wont solve those mysteries, but its measurements can help calibrate future remote observations.<\/p>\n Three cameras, an infrared spectrometer and two ground penetrating radars, like those used in the Change-3 mission, will help the spacecraft conduct its investigation of Von K\u00e1rm\u00e1n crater. Change-4 also carries some newer tech: a Swedish instrument to study how charged particles from the sun interact with the lunar surface; a German instrument to gauge radiation levels, which could be important for future astronauts; and a container with seeds and insect eggs to test whether plants and insects, if they hatch, can grow together on the moon.<\/p>\n Because the moon always shows the same face to Earth, astronomers on the ground wont be able to communicate directly with Change-4. So in May, the Chinese space agency launched a transmission relay satellite<\/a> to a point beyond the moon to bounce data and communication signals back and forth between the lunar surface and Earth (SN Online: 5\/20\/18). That satellite, called Queqiao, is named after the mythical bridge of magpies that spans the Milky Way once a year to enable a tryst between two lovers.<\/p>\n Sometime in 2019, the Change-5 craft will visit a region on the near side of the moon that no spacecraft or astronaut has been to before. And that mission will give scientists something they havent had in more than four decades \u2014 new lunar rock samples.<\/p>\n So far, scientists have studied rocks from lava fields formed early in the moons history, about 3.5 billion years ago. Those were brought to Earth by the U.S. Apollo missions, which ended in 1972, and the Soviet Luna missions, ending in 1976. Together, those missions brought back more than 380 kilograms of moon material.<\/p>\n Change-5s lander will scoop surface rocks and dig two meters deep in a 58,000-square-kilometer area called the R\u00fcmker region thats strewn with minerals dating to a variety of periods of volcanic activity. The craft will then bundle up to two kilograms of material into a rocket, which will launch to meet Change-5s orbiter and return to Earth.<\/p>\n Moon rocks brought back by the Soviet Unions Luna missions (yellow) and NASAs Apollo missions (blue) in the 1960s and 70s all came from ancient lava flows mostly clustered around the moons equator. In 2013, Chinas Change-3 (red square) landed in a different zone of old flows farther north, but brought back no samples. The Change-5 mission will return volcanic rocks from an area that has never been sampled before (outlined in red).<\/p>\n Studying samples from this region could reveal if the moon has been geologically active more recently than previously thought. \u201cAccording to the study of Apollo samples, people think the moon was dead\u201d for the last 3 billion years, Xiao says. But observations from previous orbiters suggest that R\u00fcmker includes basalt from lava flows that are less than 1.4 billion years old. \u201cIf the young mare basalt were confirmed, we would rewrite the heat history of the moon\u201d \u2014 in other words, when the moons hot liquid rock cooled and hardened<\/a> (SN: 8\/5\/17, p. 7).<\/p>\n Understanding the moons volcanic history could shed light on competing ideas about how the moon came to be. For instance, scientists still dont agree on whether our neighbor formed from one giant impact with Earth in the early days of the solar system, around 4.5 billion years ago, or from about 20 small ones, or something else. Finding evidence for more recent geologic activity could be a ding for the single impact hypothesis.<\/p>\n Whats more, the returned samples would also be stored and preserved \u201cso that future scientists who arent born yet can answer future questions we havent asked yet, with tools we havent invented yet,\u201d says astrochemist Jamie Elsila of NASAs Goddard Space Flight Center in Greenbelt, Md. She would know: Born nearly two years after the last Apollo mission, Elsila published a study in 2016 that used modern techniques to show that Apollo soil samples contain amino acids<\/a> mostly derived from Earth.<\/p>\n The prospect of studying those new rocks has excited NASA researchers and other scientists. Sample return is \u201cthe gift that keeps on giving,\u201d says former Apollo astronaut Harrison \u201cJack\u201d Schmitt, the only geologist to walk on the moon. \u201cAll of my colleagues who work directly with the samples certainly would like to get their hands on [those new rocks].\u201d<\/p>\n But U.S. scientists face roadblocks to studying the new samples, thanks to the Wolf Amendment, a 2011 federal budget clause that requires congressional approval before U.S. scientists can collaborate with China or any Chinese-owned company.<\/p>\n \u201cIn terms of space science, I think with the Wolf Amendment, the United States took very careful aim and shot ourselves in the foot,\u201d says space policy analyst Joan Johnson-Freese of the U.S. Naval War College in Newport, R.I. \u201cWeve made it very difficult for American scientists to work with otherwise unobtainable data.\u201d<\/p>\n Difficult, but not impossible. American scientists could join scientists from other countries who can work directly with China, using their colleagues as a sort of go-between. The United States could also trade Apollo samples for Change-5 samples, says space policy analyst Scott Pace, the executive secretary of the U.S. National Space Council.<\/p>\n \u201cI think the U.S. and Russia would certainly be open to being part of a sample exchange process,\u201d Pace says. \u201cFrom a purely science standpoint, wed love to have that. Whether the politics allows it, well have to see.\u201d<\/p>\n From China, Xiao agrees that collaboration is essential to understanding the moons history. \u201cWe dont want this kind of thing to badly impact the science.\u201d<\/p>\n <\/a><\/strong> <\/a><\/p>\n","protected":false},"excerpt":{"rendered":" China is about to make space history. In December, the country will launch the first spacecraft ever..<\/p>\n","protected":false},"author":1,"featured_media":99136,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[],"class_list":["post-99135","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science"],"yoast_head":"\nDelving into geologic history[hhmc]
\n<\/h4>\nMarking the spot[hhmc]
\n<\/h4>\n![\"moon](\"https:\/\/www.sciencenews.org\/sites\/default\/files\/images\/110218_lg_moon_inline_map_730_rev.jpg\" "\\"~~")
<\/p>\nTricky access to new moon rocks [hhmc]
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