The image above shows the culmination of the Chinese space agency’s Chang’e 4 mission to the dark side of the Moon. In the photo, the mission’s Jade Rabbit 2 lunar rover can be seen rolling off its Chang’e 4 parent craft. Consequently, it has now become the first man-made object to land on the side of the Moon that we cannot see directly from Earth. The illumination in this image is provided by the lander.
CNSA, the Chinese space agency, is the first to admit that its space technology lags far behind that of America and Russia. Nevertheless, its Chang’e 4 mission has managed to do what the worlds’ major space agencies could not, which is to land a spacecraft successfully on the so-called dark side of the Moon. The historic event took place on the 3rd of January 2019. Moreover, the engineers who designed and built the lander also programmed the craft to pick its own landing spot, which is another world first.
However, as impressive as the autonomous landing was, there were sound reasons for attempting it, even though NASA claimed that it could not be done when that agency considered a similar proposal eight years ago. As a practical matter, the problem of landing the craft involved the fact that it could not be seen directly, and that there was therefore no way to communicate with it directly before and during the landing. Although CNSA had placed a relay satellite in orbit around the Moon in May of 2018, it proved impossible to synchronise its orbit with the position of the lander during the approach and landing, hence the decision to allow the craft to pick its own landing spot.
Named After Chinese Moon Goddess
Appropriately, Chang’e is named after the Chinese Moon goddess, with the first Chang’e 1 lunar orbiter launched back on 24 October 2007. The Chang’e 4 robotic lander and its Yutu 2 (“Jade Rabbit No. 2”) rover were subsequently launched on 7 December 2018 before entering the Moon’s orbit on 12 December 2018. The robotic Chang’e 4 lander is now in a relatively flat spot near a small crater in the South Pole-Aitken Basin, which is not only among the largest impact basins in the solar system, but also among the oldest. It is thought to have been created during the Late Heavy Bombardment epoch’.
The Late Heavy Bombardment occurred between about 3.9 billion, and about 4.4 billion years ago, and was a particularly violent period in the solar systems’ early history. Orbital and dynamical instabilities of the gas giants caused huge changes in orbital resonances between nascent dwarf planets and asteroids at this time, which resulted in many massive bodies being flung into the inner solar system, and it is believed that the South Pole-Aitken Basin was formed when such a body crashed into the Moon.
Chang’e 4 Mission Objectives
One of the experiments aboard the Chang’e 4spacecraft is designed to analyse the soil in the impact basin not only to test the impact hypothesis, but also to investigate the chemical composition of the putative body that crashed into the Moon. According to planetary scientists from across the world, these findings might fill in some of the gaps in their knowledge about conditions in the solar system’s early history.
Although standard models of planetary formation provide partial explanations on why, how, and when planetary systems form, many questions remain, and it is hoped that the Chinese mission will provide some of the answers. These would be particularly helpful not only in the search for exoplanets, but also in the search for multiple-planet exo-solar systems.
One other major mission objective involves low frequency radio astronomy experiments. Since the dark side of the Moon always faces away from Earth, that side of the Moon is completely shielded from radio interference that originates on Earth, which means that radio telescopes on the far side of the Moon will be able to look much further back into time than Earth-based instruments can. In fact, radio astronomers are confident that a dark-side based instrument should be able to look back to within about 50 to 100 million years after the Big Bang, which should shed some more light on the conditions in the Universe when the first stars started to form.
Biological Experiment Onboard
When viewed objectively purely as an engineering feat, the current Chinese mission represents not only several world-firsts, but also a huge leap forward in lunar exploration. Interestingly, the Chinese lander also hosts a biological experiment, the purpose of which is to see if silkworm larvae and plants can form a simple synergy within a small container. In essence, the silkworms would produce CO2 and the plants (if the seeds germinate) would produce oxygen, and it is hoped that if the experiment is successful, the results could be used as the basis for plans to develop life support systems for humans on long space fights.
While manned deep space flights are still a long way off, all journeys start with the first step, which in the case of the Chang’e 4 mission is a bigger one than usual.