China heads over to the dark side of the moon
CHANG’E 4 TO OFFER FIRST CLOSE-UP LOOK AT A PART ETERNALLY OUT OF VIEW FROM EARTH
China’s space agency has not announced a landing date, though some expect that will be the first week of January, when the sun will be shining over the far side of the moon, an important consideration because Chang’e-4 is solar-powered.
China has collaborated with other countries. One instrument was developed at Kiel University in Germany; another was provided by the Swedish Institute of Space Physics.
China is aiming to go where no one has gone before: the far side of the moon. A rocket carrying the Chang’e-4 lunar lander blasted off at about 2.15am local time yesterday from Xichang Satellite Launch Centre in southern China.
Exactly when it will set down at its destination has not yet been announced — possibly in early January — but Chang’e-4 will provide the first close-up look at a part of the moon that is eternally out of view from earth.
Chang’e-4 includes two main parts: the main lander weighing about 1,089 kilograms and a 136kg rover. By comparison, Nasa’s Opportunity rover on Mars weighs about 181kg, and the Curiosity rover there is much bigger, at 907kg.
The spacecraft is largely a clone of Chang’e-3, which landed on the moon in 2013. Indeed, Chang’e-4 was built as the backup in case the first attempt failed. With the success — the first soft landing of any spacecraft on the moon since 1976 — the Chinese outfitted Chang’e-4 with a different set of instruments and decided to send it to a different location.
The rover will land in the 177km-wide Von Karman crater. It is on the far side of the moon, which is always facing away from earth. (The moon is what planetary scientists call “tidally locked” to the rotation of the Earth. That is, its period of rotation — its day — is the same as the time it takes to make one orbit around earth.)
Over to the dark side
The crater is within an area known as the South Pole-Aitken basin, a gigantic, 2,575kmwide crater at the bottom of the moon, which has a mineralogy distinct from other locations. That may reflect materials from the inside of the moon that were brought up by the impact that created the basin.
The far side is also considerably more mountainous than the near side for reasons not yet understood.
The suite of instruments on the rover and the lander include cameras, groundpenetrating radar and spectrometers to help identify the composition of rocks and dirt in the area. And China’s space agency has collaborated with other countries.
One instrument was developed at Kiel University in Germany; another was provided by the Swedish Institute of Space Physics.
The instruments will probe the structure of the rocks beneath the spacecraft, study the effects of the solar wind striking the lunar surface. Chang’e-4 will also test the ability of making radio astronomy observations from the far side of the moon, without the effects of noise and interference from Earth.
According to the Xinhua News Agency, Chang’e-4 is also carrying an intriguing biology experiment to see if plant seeds will germinate and silkworm eggs will hatch in the moon’s low gravity.
Because the moon blocks radio signals from our planet, the Chinese launched a satellite — called Queqiao — in May. It is circling high over the far side of the moon, and will relay messages between Earth and the Chang’e-4 lander.
There has been no announcement of live coverage of the launch. China’s space agency has not announced a landing date, though some expect that will be the first week of January, when the sun will be shining on the far side of the moon, an important consideration because Chang’e-4 is solar-powered.
Zhang Xiaoping, an associate professor from Space Science Institute/Lunar and Planetary Science Laboratory of Macau University of Science and Technology, said that the spacecraft would follow the Chang’e-3’s trajectory. That means it would arrive in three to five days and then orbit the moon for several days (13 in the case of Chang’e-3) while preparing for the landing, he said. The far side is not dark all the time.
The first new moon of 2019 is January 6. That’s when you cannot see the moon because the dark side — the side that is in shadow facing away from the sun — is facing Earth. And when the near side of the moon is dark, the far side is awash in bright sunshine.
Chang’eing up
Chinese officials have talked about Chang’e-4 in public, but their interactions with journalists more resemble the carefully managed strategy used by the Soviet programme during the Cold War rather than the more open publicity by Nasa and many other space agencies. That way, the Chinese, like the Soviets, could boast about the successes and downplay any failures.
In Chinese mythology, Chang’e is the deity of the moon. Other missions have been named after her, too.
The next step in China’s moon programme is for the Chang’e-5 robotic spacecraft to land on the moon and then bring rock samples back to Earth for additional study.