China sets out for the far side of the moon

first_imgThe moon’s far side has a thick, old crust and is pockmarked by many deep craters. China sets out for the far side of the moon By Dennis NormileNov. 29, 2018 , 12:00 PM Chang’e-4 will explore a 12-kilometer-deep lunar crater likely formed by a giant asteroid impact. Sign up for our daily newsletter Get more great content like this delivered right to you! Country CNSA Click to view the privacy policy. Required fields are indicated by an asterisk (*) SHANGHAI, CHINA—China’s ambitious program of lunar exploration is about to attempt a spacefaring first: On 8 December it will launch a probe intended to land on the far side of the moon. Besides boasting rights, the Chang’e-4 lander and rover are expected to produce a host of new insights into the moon’s composition and history. “Chang’e-4 is an historical mission,” says Bernard Foing, director of the European Space Agency’s (ESA’s) International Lunar Exploration Working Group in Noordwijk, the Netherlands.Remote observations have shown that the far side of the moon, invisible from Earth, has a much thicker, older crust and is pockmarked by more and deeper craters than the near side, where large dark plains called maria, formed by ancient lava flows, have erased much of the cratering. The big difference “is still a mystery,” Foing says, and Chang’e’s trip “can give clues.”China started its lunar program 3 decades after the United States and the Soviet Union ended theirs. Chinese geologists eager to study the moon convinced the government to establish the Lunar Exploration Program under the China National Space Administration (CNSA) in 2004. The agency launched Chang’e-1 and Chang’e-2, named after a Chinese moon goddess, in 2007 and 2010, respectively; both produced “a lot of good science,” including high-resolution lunar images and new altimetry measurements, says planetary scientist James Head of Brown University. Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe In 2013, Chang’e-3 became the first craft to land on the moon since the Soviet Union’s Luna 24 sample return mission in 1976. The lander and the small rover it carried gathered data on the moon’s topography, mineralogy, and elemental abundance. In a first, the rover was equipped with a ground-penetrating radar that profiled buried lava flows and regolith, the broken up rock and dust that makes up the lunar soil.Chang’e-4 was designed as an identical backup to Chang’e-3, but when that mission proved successful, China’s planners became more ambitious. Going to the far side promised “unique and original science” as well as a chance to “develop China’s deep space observational capabilities,” says Li Chunlai, deputy director-general of the Chinese Academy of Sciences’s National Astronomical Observatories of China (NAOC) in Beijing, which advises CNSA on the program’s science objectives. Because the moon will block direct radio contact with the lander and rover, Chang’e-4 will rely on a communications relay satellite, launched in May. Called Queqiao, it’s traveling in a loop 65,000 kilometers beyond the moon at Earth-moon Lagrange Point 2, a gravitational balance point. Chang’e-4 itself will land in the Von Kármán crater within the South Pole–Aitken basin. Likely formed by a giant asteroid impact, the basin is roughly 2500 kilometers across and 12 kilometers deep. “It’s the moon’s largest, deepest, and oldest impact structure,” says planetary geoscientist Xiao Long of the China University of Geosciences in Wuhan.The impact may have brought material from the moon’s upper mantle to the surface, a scenario that data from a visible and near-infrared imaging spectrometer might be able to verify. The imaging spectrometer will also explore the geochemical composition of far-side soil, which is likely to differ from the near side because of the same processes that produced the difference in crust thickness.The rover’s ground-penetrating radar—similar to that on Chang’e-3—will provide another look down to about 100 meters beneath the surface, probing the depth of the regolith and looking for subsurface structures. Combining the radar data with surface images from cameras on the lander and rover might advance scientists’ understanding of the cratering process.Going to the far side also opens “a totally new window for radio astronomy,” says Ping Jinsong, a NAOC radio astronomer. On Earth, and even in near-Earth space, natural and humanmade interference hampers low-frequency radio observations. The moon blocks this noise. So the mission carries a trio of low-frequency receivers: one on the lander, one—a collaboration with the Netherlands—on Queqiao, and a third on a microsatellite released from Queqiao into a lunar orbit. (Contact with a second microsatellite carrying a fourth receiver has been lost.) The receivers will listen for solar radio bursts, signals from aurorae on other planets, and the faint signals from the primordial clouds of hydrogen gas that coalesced into the universe’s first stars.China’s ambitious lunar program will continue with Chang’e-5, a sample return mission, due for launch next year. It will retrieve up to 2 kilograms of soil and rock from the Oceanus Procellarum, a vast lunar mare on the near side untouched by previous landings, and one of the moon’s youngest volcanic flows. “It’s a great objective and will potentially yield some fantastic science,” says Bradley Jolliff, a planetary scientist at Washington University in St. Louis, Missouri, who has urged the United States to launch its own lunar sample return mission.If China continues its tradition of developing moon missions in pairs, a second sample return mission, Chang’e-6, might follow. Head notes that NASA, ESA, Japan, Russia, and India have all taken a renewed interest in our planet’s companion, which holds clues to Earth’s own history. “Chang’e-4 and 5 are a major part of this renaissance,” Head says, “and in many ways are the current vanguard.” Email NASA/GODDARD/ARIZONA STATE UNIVERSITY last_img read more