The Moon, the nearest celestial object to Earth, has sparked a greater sense of wonder and fascination than any other element in the sky. Exploring the Moon offers a valuable opportunity to unravel the early development of both the solar system and our own planet.
O Moon! We should be able to know you through our intellect,
You enlighten us through the right path.
Àgveda Part – I/91/1
(About 2000 years B.C)
Early Curiosity in Moon:
Our ancestors used its positions and phases to mark the passage of time. Around 450 B.C., the idea that the Moon’s surface was not perfectly smooth emerged. Greek astronomer Hipparchus made remarkable advancements, precisely measuring the distance to the Moon and the Sun using observations and mathematical formulae. During the Vedic period (1500-500 B.C.), Indian astronomers made precise determinations of the Moon’s orbit and developed the lunar calendar, which is still in use today. Indian astronomer Aryabhatta (500 A.D) accurately determined the Moon’s size and distance, leaving a lasting impact on lunar research.
In the early 17thcentury, Galileo, using his newly invented telescope, provided a closer look at the Moon, revealing its uneven surface with dark lowland areas and bright highlands. Lunar photography, facilitated by a 5-inch reflector telescope in 1840, became an established branch of astronomical research by 1890.In 1946, scientists used radar to receive a reflected signal from the Moon, opening up new possibilities for lunar exploration and study.
Selenography is the study and science of the surface features, characteristics, and topography of the Moon. It involves the observation, mapping, and analysis of lunar landscapes, including the examination of craters, mountains, valleys, plains, and other geological formations on the Moon’s surface.
Major Lunar Missions:
| Name | Nation | Year | Type | Results |
| Pioneer 0 | USA | 1958 | Orbiter | Unsuccessful |
| Luna 1 | USSR | 1959 | Orbiter | Partial Successful |
| Luna 2 | USSR | 1959 | Impact | Successful, first spacecraft to impact the moon |
| Luna 3 | USSR | 1959 | Orbiter | Successful, first picture of the lunar far side |
| Ranger 7 | USA | 1964 | Impact | Successful, first US close-up pictures of the moon |
| Zond 3 | USSR | 1965 | Flyby | Successful |
| Surveyor 5 | USA | 1967 | Lander | Successful |
| Apollo 10 | USA | 1969 | Orbiter | Successful |
| Apollo 11 | USA | 1969 | Orbiter | Successful, first humans to land on the moon |
| Chang’e 1 | China | 2007 | Orbiter | Successful |
| Chandrayaan 1 | India | 2008 | Orbiter | Successful |
| Chang’e 2 | China | 2010 | Orbiter | Successful |
| Chang’e 4 | China | 2018 | Lander | Successful |
| Beresheet | Israel | 2019 | Lander | Unsuccessful, first lunar landing by a private company |
Read more about Luna 25 and Luna mission of USSR
Chandrayaan-1
Chandrayaan-1, India’s first mission to the Moon was launched on 22 October 2008.It was launched from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota, Andhra Pradesh using the Polar Satellite Launch Vehicle (PSLV-C11).
Primary science objective of the mission –
- To prepare a three dimensional atlas of both near and far side of the Moon
- To conduct chemical and mineralogical mapping of the entire lunar surface with high spatial resolution.
NASA’s role in Chandrayaan-1:
- Locating Chandrayaan-1: NASA’s Jet Propulsion Laboratory (JPL) successfully located ISRO’s Chandrayaan-1 spacecraft, which was found orbiting about 200 km above the lunar surface.
- Ground-based Radar Technology: The achievement was made possible using ground-based radar technology, where microwave beams were sent towards the moon, and their echoes were received to precisely track the lost spacecraft’s position.
- Utilizing NASA’s 70-meter Antenna: NASA’s 70-meter antenna at the Goldstone Deep Space Communications Complex in California was employed to transmit a powerful microwave beam directed at the moon.
- Receiving Radar Echoes with Green Bank Telescope: The radar echoes from the lunar orbit were received using the 100-meter Green Bank Telescope in West Virginia.
- Application to Voyager-I Spacecraft: This same radar technology has been effectively used by NASA to communicate with the Voyager-I spacecraft, which has ventured to the outermost regions of the solar system.
Findings of Chandrayaan-1:
- Hematite Discovery at Lunar Poles: Moon Mineralogy Mapper (M3) indicates the presence of hematite(form of iron oxide) at the lunar poles. While the moon’s surface is recognized for its abundance of iron-rich rocks, there is currently no evidence of water and oxygen, the two elements required to facilitate the interaction with iron and form rust.
- Discovering Abundant Metals in Moon’s Subsurface: NASA found evidence that the Moon’s subsurface might have greater quantities of metals such as iron and titanium than thought before.
- Discovery of Hydroxyl (OH) and Water (H2O) Molecules: It made a groundbreaking revelation of the presence of hydroxyl and water molecules on the lunar surface.
- Other scientific results:
- Subsurface Water-Ice Deposits in Craters
- Possible Water Molecules in Lunar Environment
- Validation of Lunar Magma Ocean Hypothesis
- Reflection of Solar Wind Protons
- Presence of Metals such as Mg, Al, Si, and Ca on Lunar Surface
- 3D Conceptualization of Lunar Craters
Chandrayaan-2
India launched its second lunar exploration mission, Chandrayaan-2, on 22 July 2019 from the Satish Dhawan Space Centre in Sriharikota.
Chandrayaan-2 is an integrated 3-in-1 spacecraft comprising of an Orbiter of the Moon, Vikram (lander) and Pragyan (rover) launched using GSLV MK III M1. The Orbiter will orbit from 100 km away, while the Lander and Rover modules will separate and make a soft-landing on the surface.
Objective:
- To map the location and abundance of lunar water.
- The composite module of Chandrayaan 2 comprises technology and software developed across the country, includes a wholly indigenous rover and India’s first lander capable of executing a ‘soft landing’.
Vikram Lander:
It isnamed Vikram after Dr.Vikram A Sarabhai, the Father of the Indian Space Programme.It is designed to function for one lunar day, which is equivalent to about 14 Earth days. Vikram has the capability to communicate with IDSN, the Orbiter and Pragyan rover. The lander is designed to execute a soft landing on the lunar surface at a touchdown velocity of 2 metres per second. After landing, it will remain stationary and primarily focus on studying the moon’s atmosphere while also monitoring for any seismic activity.
Pragyan Rover:
It is a 6-wheeled robotic vehicle named Pragyan, which translates to ‘wisdom’ in Sanskrit. It can travel up to 500 m at a speed of 1 centimetre per second, and leverages solar energy for its functioning. It can communicate with the lander. It will analyze the surface composition in the vicinity of the lunar landing site, assessing the presence and abundance of different elements.
Orbiter:
The Orbiter, equipped with 8 instruments, was scheduled to stay in orbit for 1 year. The mission is equipped with a variety of cameras to generate high-resolution 3D maps of the lunar surface. It aims to investigate the moon’s mineral composition, atmospheric properties, and the presence of water resources.
What went wrong?
On August 20, 2019, the spacecraft reached the Moon’s orbit and started preparing to land the Vikram lander. The plan was for the lander and rover to land on the Moon’s near side in the south polar region. Unfortunately, during the early hours of September 7, the lander and rover crash-landed on the Moon’s surface. The reason for the crash was a problem with the software that caused the spacecraft to tilt too much, in the wrong direction, instead of landing properly as intended.
Chandrayaan 3
Chandrayaan-3 is India’s 3rd lunar mission, aiming for a soft landing on the moon’s surface, making it the country’s 2nd attempt at achieving this feat. The mission launched from the Satish Dhawan Space Center (SDSC) in Sriharikota on July 14, 2023, at 2:35 pm. It comprises an indigenous Lander module (LM), Propulsion module (PM), and a Rover. The primary objective of Chandrayaan-3 is to develop and demonstrate new technologies essential for future interplanetary missions.
Objectives –
- Probe the elemental and mineral composition of lunar surface.
- Study the charge and ion activity in the lunar atmosphere close to surface.
- Find out the structure of Lunar mantle and crust by studying moonquakes.
- Measure thermal conductivity and temperature profile of the lunar surface.
- Prepares the way for future planetary missions by demonstrating safe landing and rover maneuver.
Scientific Payloads in Chandrayaan 3:
Chandrayaan-3’s lander (Vikram) and rover payloads (Pragyan) are identical to those used in the Chandrayaan-2 mission. However, the propulsion module of Chandrayaan-3 includes a new experiment named Spectro-polarimetry of Habitable Planet Earth (SHAPE).
SHAPE (Spectro-polarimetry of HAbitable Planet Earth): An experimental payload to study the spectro-polarimetric signatures of the habitable planet Earth in the near-infrared (NIR) wavelength range (1-1.7 μm).
| Feature | Chandrayaan-2 | Chandrayaan-3 |
| Landing Area Flexibility | Limited designated zone | Expanded designated area |
| Fuel Capacity | Standard | Increased for longer-distance travel |
| Solar Panels | On two sides | On all four sides |
| Utilization of Chandrayaan-2 Orbiter | High-resolution images used for landing location | Physical ModificationsMade to enhance stability and sturdiness |
| Additional Navigational Instruments | —- | Laser Doppler Velocimeter for speed measurement |
What Next?
Chandrayaan-3 was successfully launched using the LVM3 M4 launcher. About 16 minutes after liftoff, the spacecraft separated from the rocket and entered an elliptic parking orbit (EPO). The entire journey of Chandrayaan-3 is expected to take around 42 days, with the landing planned for August 23, 2023, during the lunar dawn.
The mission duration for the lander and rover is limited to one lunar day, which is approximately 14 Earth days, as they rely on solar energy for their operations. The chosen landing site for Chandrayaan-3 is located near the lunar south pole.
