Recently, a team of Chinese researchers announced the creation of a satellite orbiting the moon’s surface. This satellite has a period (time it takes to complete one orbit) of around one hour.
This is an astonishing achievement, as most satellites orbiting the moon have much longer periods. The earlier Chinese satellites had orbits that took twenty hours to complete!
How did they do it? By putting their satellite very close to the moon’s surface- only a few kilometers above the surface. This made for a quicker orbit, which shortened the satellite’s period.
The difficulty in designing and constructing such a satellite comes from understanding how gravitational pull affects your object. If you put your object too close to the gravitational field (like on the surface of the moon), it will not stay in orbit and will plunge to the earth or moon.
How it works
NRO has launched two experimental satellites orbiting the moon. The first was called Lunar Reconnaissance Orbiter and it launched in 2009.
It circled the moon for several years, gathering data and photographs of the lunar surface. A second satellite, LRO Satellite 2, was launched in 2018 as a successor to the original LRO.
Both satellites had very low orbits around the moon, just above its surface. This allowed them to gather more detailed data on the lunar surface than any previous satellites. It also put them at risk of crashing into the moon’s surface due to gravitational pull from the lunar body itself!
Satellite 3 will take over for LRO Satellite 2 and will have an even lower orbit than its predecessors. It is expected to launch in 2021 and will help with research on potential lunar resources such as water ice.
Applications of technology
The advance in space technology is not limited to the satellite itself. The launch into space and the orbiting of the moon’s surface is just as, if not more, important.
With this new satellite, researchers will be able to study gravitational waves with greater precision. Previously, researchers had to rely on data from LIGO (the Laser Interferometer Gravitational-wave Observatory) on Earth, which limited their ability to make precise predictions. With Synchro-link Research Satellite in orbit around the moon, they will have a better view of the lunar surface. This means they can better predict when gravitational waves will occur and how they will affect the moon’s surface.
This new technology could have other applications as well. Companies could use this technology to monitor assets on the lunar surface or within facilities on the moon. It could also be used to monitor spacecraft for potential collisions with objects on or around the lunar surface.
Confirm a theory about the Moon
As mentioned before, the main reason we explore space is to further our understanding of the world, even if it’s beyond our atmosphere or beyond our planet.
Exploring space allows us to confirm theories about the universe and our surroundings. For example, we have theories about how gravity works, how planets rotate and orbit each other, and how moons orbit their parent planets.
By sending satellites to photograph the Moon’s surface and its features, we can confirm that these theories are correct. If there is something unusual on the surface of the Moon, we can investigate what it is due to images taken from satellites.
Satellites also allow us to investigate other bodies in the universe, such as asteroids and Mars. We can determine whether these bodies have water or if they could support life using satellite images.
A remarkable scientific achievement
On Saturday, China launched a mission to place a satellite in orbit around the moon. The launch was from the country’s new launch facility, the Wenchang Satellite Launch Centre in Hainan.
The Chang’e-4 probe — named after a lunar goddess in Chinese mythology — will orbit within about 2 miles (3 kilometers) of the moon’s surface. This will be the first such close orbital probe of the moon in history.
The mission includes a rover that will conduct scientific experiments on the moon’s surface. The landing is planned for January next year.
This is an remarkable achievement for China, and for humanity as a whole — we have placed a satellite into such an close orbit around another celestial body! It is only the fifth satellite to be in such an orbit, after ones that were placed around Earth and our Moon.
Who did this?
The first satellite orbiting the moon was launched by China in 2007. It was called Chang’e 1 and it took pictures of the moon’s surface and transmitted them back to Earth.
Since then, a number of countries have sent satellites orbiting the moon, including Japan in 2010 (Hayabusa), India in 2013 (Chandrayaan-1), Iran in 2014 (Omid) and Brazil in 2015 (Apis).
In 2018, Israel launched its first lunar spacecraft, called Beresheet, which means “in the beginning” in Hebrew. Unfortunately, Beresheet crashed into the lunar surface after technical difficulties.
China plans to launch another probe next year to collect samples from the moon and return them to Earth. This mission will be China’s fifth and likely its last lunar probe for the near future.
Helium gas tank
In 2017, China launched a satellite into orbit around the moon. It was the first spacecraft to explore the lunar far side, and its mission includes landing on the moon’s surface and collecting samples.
The spacecraft is called Chang’e-4, which is named after a mythical goddess of the moon in Chinese mythology. It consists of two parts: a small stationary satellite orbiting near the surface of the moon and a mobile explorer that will land on the lunar surface.
Chang’e-4 launched on December 2, 2018, with two days of separation between its launch and that of Chang’e-4 Lander. The separation occurred at about 10:00 am Beijing time (03:00 UTC). The separation was confirmed by officials at China’s space agency just over an hour later.
One part of Chang’e-4 is a small helium gas tank that weighs only one kilogram (2.2 pounds), but can hold more than one cubic meter (more than one cubic yard) of helium gas.
Only one pass per location possible
An interesting fact about the moon is that no satellite can orbit it for long due to the rotation of the moon. There is only one place where a satellite can orbit the moon and have a stable orbit.
That place is called the quasi-satellite orbits and they have a period of 27 days. These orbits are very unstable and there is no chance of having a satellite in one for an extended period of time.
Satellites in these orbits have to move very quickly to avoid crashing into the moon’s surface. Due to this, there are only a few satellites that can maintain these kinds of orbits and they have to constantly move.
Quasi-satellites are interesting because they have two distinct orbital periods so they switch back and forth between orbiting the Earth or the Moon every 27 days.(www.sciencealert.
Sensors and cameras
The next thing that the Kaguya-2 contains is sensors and cameras. The sensors help the module determine its position in space as well as its position relative to the Moon’s surface.
These sensors also help the module detect whether it is facing the Moon’s surface or away from it. This is important because it enables the satellite to gather data from both sides of the lunar surface.
The cameras aboard Kaguya-2 capture high-resolution images of the lunar surface. There are two cameras, one on each side of the module, that each have a 1-megapixel resolution. These are not very high resolution compared to modern day cameras, but for a space camera, they are impressive.
These cameras were specifically designed with durability in mind due to radiation exposure and potential bumps during deployment on orbit.
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