When you last took a look at the Moon, did you think about the active spacecraft currently out there? Or could you even name them? Well, I can’t. So let us take a look at the spacecrafts and missions are currently operating around and on the Moon. Let’s start with the oldest spacecrafts.
The THEMIS-ARTEMIS spacecrafts
On 17 February 2007 a Delta II rocket soured into the sky above Cape Canaveral. It carried the five spacecraft of the THEMIS mission. The goal of the mission was to study energy releases from Earth’s magnetosphere. As well as magnetic phenomena that intensify auroras near Earth’s poles. Therefore, the spacecrafts were placed into a highly elliptical orbit. The perigee altitude was at 470 kilometers and the apogee altitude was at 87330 kilometers. But where does the Moon come into play, you ask?
In 2008 NASA extended the mission and approved moving two of the spacecrafts (THEMIS B and THEMIS C) into lunar orbit. Due to the new goals, NASA renamed the mission of these two spacecraft to “ARTEMIS”. Where ARTEMIS stands for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun. The spacecrafts also were renamed ARTEMIS P1 (THEMIS B) and ARTEMIS P2 (THEMIS C). To prevent conflicts with the new lunar exploration program, NASA in 2019 again renamed the mission to THEMIS-ARTEMIS.
From October 2009 to July 2011 both spacecraft moved from earth orbits into orbits around the Moon. While in between doing science at the Lagrange points between Earth and Moon. How exactly the orbits were changed, can be found in detail on the orbit’s page of the mission website.
By now, both spacecraft have arrived in stable lunar orbits. And they are expected to operate for a long time. Therefore, NASA is planning to use them to support the Artemis lunar exploration program. For example, they can provide real-time measurements of highly energetic particles at the Moon. This data can in this case be used for early warnings about incoming storms and a broader understanding of the environment. The data will help to protect future spacecrafts, vehicles and astronauts around and at the surface of the Moon.
The Lunar Reconnaissance Orbiter (LRO)
Two years later, NASA launched the Lunar Reconnaissance Orbiter. A mission dedicated to exploring the Moon. It was launched into earth orbit on top of a ULA Atlas V on 18 June 2009. Later it transferred to a lunar orbit, which it entered on 23 June 2009. The exploration mission started on 15 September 2009.
The full name “Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite missions” is a clue about the goals of the missions. In this case, to performed two different missions with one spacecraft. It started with the Exploration mission. The focus of the mission was to support the extension of human presence in the solar system. This was achieved by helping to identify sites close to potential resources with high scientific value. As well as locating favorable terrain and environments for safe future robotic and human exploration.
The Exploration mission finished on 15 September 2010. Responsibility for the spacecraft was then transferred to NASA’s Science Mission Directorate. This started a two-year science mission. The mission has since been extended. Until today, LRO is transmitting data for:
- Day-night temperature maps
- A global geodetic grid
- The moon’s UV albedo
- High-resolution color imaging
The lander of the Chang’e 3 mission
In 2004 China started the Chinese Lunar Exploration Program also known as Chang’e Project. The project is named after Chang’e, the goddess of the Moon in Chinese mythology. It is split into four phases. Phase I, with the missions Chang’e 1 and Chang’e 2, has already been completed successfully. Chang’e 3 hence is the third mission in this program and the first mission of Phase II.
It incorporates China’s first lunar lander and first lunar rover (named Yutu). The spacecrafts were launched on 1 December 2013 by a Long March 3B. The mission achieved lunar orbit on 6 December 2013. It then landed successfully on 14 December 2013. In doing so, it became the first spacecraft to soft-land on the Moon since 1976.
The technological goals of the mission were to soft land and drive around on the Moon. As well as to demonstrate and develop technologies for future missions. The scientific goals of the mission are studding the lunar environment as well as lunar-based astronomical observations. This includes:
- Lunar surface topography and geology survey
- Lunar surface material composition survey
- Resource survey
- Sun-Earth-Moon space environment detection
It will attempt to perform the first direct measurement of the structure and depth of the lunar soil. In this case, down to a depth of 30 m. And it will investigate the lunar crust structure down to several hundred meters depth.
The rover has stopped transmitting data in March 2015. But the lander and its telescope are still operational as of September 2020. And it might be active for a long time, as its power source could last for 30 years.
The Chang’e 4 mission
After the successful landing of Chang’e 3, China launched Chang’e 4 on 7 December 2018. Like Chang’e 3 the spacecraft consists of a lander and a rover. In fact, it was originally built as a backup for Chang’e 3. And later was modified to meet the new mission requirements. More on these later.
The lander performed the first soft-landing on the far side of the Moon on 3 January 2019. It landed in the Von Kármán crater. This is a large crater within the moon’s South Pole-Aitken basin. It formed because of an ancient collision event. The crater was selected because an impact of this size might have exposed the deep lunar crust and interior. It is roughly 2,500 km in diameter and 13 km deep. It therefore is the single-largest impact basin on the Moon and one of the largest in the Solar System. By studying the craters’ scientist want to find out more about the history of the Moon and Earth.
But wait a minute, as the far side of the Moon is always facing away from Earth, how does the communication work? To control the rover and communicate with the lander, China launched a relay satellite to the Earth-Moon L2 Point. About which I will talk in a later post.
Back to the instruments aboard the lander and rover. Which include international instruments, for example a particle detector from Germany and an ion detector from Sweden. The goals of the mission are to measure:
- The chemical compositions of lunar rocks and soils
- The temperature of the lunar surface
The unique location on the far side of the Moon allow for some unique science, like low-frequency radio astronomy. This is possible because the Moon is shielding the lander from sources located on Earth. Aside from astronomical observations, the goals include the study of cosmic rays as well as observation of the solar corona.
The Chandrayaan-2 mission
On 22 July 2019 ISRO from India launched the Chandrayaan-2 mission. Like the Chang’e 4 mission from China, the spacecraft consists of an orbiter, lander and rover. As well as representing a significant technological leap for IRSO compared to the previous mission. The orbiter-lander-pair entered lunar orbit on 20 August 2019. Unfortunately, the lander and rover crashed into the Moon on 6 September 2019 while trying a soft-landing on the surface.
So, it was left to the orbiter to fulfill the mission goals. Which are to map and study the variations in lunar surface composition, as well as the location and abundance of lunar water. Therefore, the orbiter is equipped with 8 instruments:
- Terrain Mapping Camera – 2 (TMC-2)
- Orbiter High Resolution Camera (OHRC)
- Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS)
- Solar X-ray Monitor (XSM)
- Imaging Infra-Red Spectrometer (IIRS)
- Dual frequency Synthetic Aperture Radar (DFSAR)
- Chandra’s Atmospheric Composition Explorer–2 (CHACE-2)
- Dual Frequency Radio Science Experiment (DFRS)
The orbiter of the Chang’e 5 mission
After the successful Chang’e 4 mission, China on 23 November 2020 launched another mission to the Moon. Consequently, the mission name is Chang’e 5. It is the second mission of phase three of the China Lunar Exploration Program. The first mission of phase three was a test of the atmospheric re-entry.
The Chang’e 5 spacecraft consists of four modules, an orbiter, a lander, an ascender and a returner. After the launch, the spacecraft transferred to a lunar orbit. There, the lander and ascender separated and shortly after softly landed on the surface of the Moon on 1 December 2020. The lander later used a robotic arm to collect samples from the surface. It then delivered them to the ascender. Which later lifted of from the surface and docked again to the orbiter in lunar orbit. The ascender eventually transferred the samples to the returner. The orbiter and returner separated from the ascender and left lunar orbit to return to earth.
A few thousand kilometers away from earth, orbiter and returner separated. The returned later entered the atmosphere and landed successfully on 16 December 2020. The orbiter continued on and visited the Sun-Earth Lagrange point 1. It recently returned to the Earth-Moon system.
The mission delivered the first lunar samples since the Soviet Union’s Luna 24 in 1976. With an age of around 2 billion years, the samples are the youngest so far returned to earth. The scientific results of the mission are available under https://moon.bao.ac.cn/ce5web/moonGisMap.search.
More about the spacecrafts on and at the Moon
Do you want to know more about the spacecrafts? Take a look at the websites listed below.
Want to learn more related to the Moon? Click here for a list of posts with the tag Moon.