The View from Yutu 2

The View from Yutu 2

China’s lunar rover Yutu-2 rolled off of the Chang’e-4 lander today (Eastern Standard Time) giving the first view of the far side of the Moon from the surface.  Although the far side has been imaged by orbiters for decades, this is the first time a spacecraft has soft landed there.  Chang’e-4 arrived last night, setting down in the Moon’s South Pole-Aitken Basin at a place called the Von Kármán crater, a place of great scientific interest.

This is China’s second lunar lander.  The first, Chang’e-3 and its rover Yutu, have been on the near side of the Moon since December 2013.  The Chang’e-3 lander is still transmitting data back to Earth, but Yutu suffered mechanical problems and could not complete its planned trek.

Chang’e is the name of China’s mythological goddess of the Moon.  Yutu is her pet jade rabbit.

Chang’e-4 was designed as a backup to Chang’e-3. Despite the problems with Yutu, China considered that mission a success so decided to use Chang’e-4 for the riskier farside mission.   The far side always points away from Earth, but, like the near side, gets 14 days of sunlight and 14 days of darkness.

Mission controllers cannot communicate with a spacecraft on the surface of the far side because there is no line of sight back to Earth.  China launched a communications satellite, Queqiao, which is in a special lunar orbit that is in constant view of both Earth and Chang’e-4 relaying signals back and forth.

Beijing is 13 hours ahead of Eastern Standard Time (EST).  Chang’e 4 landed on January 2 at 9:26 pm EST, which was January 3 at 10:26 am Beijing Time.

One of the first images returned from Chang’e-4 showed its landing site at 177.6 degrees east longitude, 45.5 degrees south latitude in the Von Kármán crater.  The far side is more heavily cratered than the near side and a small crater is visible close to the lander.

Photo provided by the China National Space Administration on Jan. 3, 2019 shows the first image of the moon’s far side taken by China’s Chang’e-4 probe. China’s Chang’e-4 probe touched down on the far side of the moon Thursday, becoming the first spacecraft soft-landing on the moon’s uncharted side never visible from Earth. The probe, comprising a lander and a rover, landed at the preselected landing area at 177.6 degrees east longitude and 45.5 degrees south latitude on the far side of the moon at 10:26 a.m. Beijing Time (0226 GMT), the China National Space Administration announced. (Xinhua)

Like Chang’e-3, Chang’-4 has a rover, but China did not announce its name until after the spacecraft landed safely.  The name is — Yutu-2.

It rolled off the lander and onto the lunar surface as shown in this photo tweeted by @cosmicpenguin and attributed to China’s CCTV as posted on Weibo, a Chinese blogging website, but does not appear to be on the CCTV website itself.  The CCTV caption says it was deployed at 22:22 January 3, which presumably is Beijing time, which would be 11:22 am EST today.

The landing site in the Von Kármán crater is part of the oldest, largest and deepest impact basin on the Moon.  It stretches across a quarter of the Moon and is 8 kilometers deep.  Instruments on U.S. and Indian spacecraft have confirmed that water ice exists in permanently shadowed craters at both of the Moon’s poles, deposited by impacts from comets and asteroids over eons and preserved in the darkest and coldest locations.  Scientists are eager to obtain more data about that part of the Moon.

The crater is named after Theodore von Kármán (1881-1963), a Hungarian-American mathematician, engineer and physicist who helped found the Jet Propulsion Laboratory (JPL), which is now operated for NASA by the California Institute of Technology and builds many of NASA’s planetary spacecraft.  Xinhua pointed out today that two men considered the fathers of the Chinese space program, Qian Xuesen and Guo Yonghuai, were students of von Kármán.

This is the first spacecraft to land on the far side of the Moon and its predecessor, Chang’e-3, is still partially operational on the near side so China has two operational rovers on the Moon at the same time.  Despite this impressive achievement, China provided little information about when the landing would take place, saying only that it would be early in January.

Last night, China’s CGTN network tweeted just after 10:00 pm EST that Chang’e-4 had landed, but immediately deleted the tweet sparking concern among those eagerly awaiting news that something had gone awry.  It was not until an hour later than CGTN tweeted the news a second time and special segments about the successful landing aired on that channel and CCTV.  The landing was at 9:26 pm EST, so the original tweet was already more than 30 minutes after the event took place.

China’s lack of transparency was irksome, especially when compared with how NASA and the New Horizons team shared information about the flyby of Kuiper Belt Object (KBO) Ultima Thule on New Year’s Day.  In that case cameras were in the room showing mission controllers receiving the signals that indicated whether or not the spacecraft was healthy and had collected data.  That was in addition to several press conferences held before and after the flyby and a New Year’s celebration party including the media as the flyby took place at 12:33 am January 1, a date and time announced far in advance.


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