India’s Chandrayaan-2 and China’s Chang’e-4: A detailed comparison

Chang’e 4 is a very special mission of China who had made a history and became the first country to land a spacecraft on the far side of the moon. And the same is expected to be repeated soon by India with Chandrayaan-2. The far side of the moon is known as ‘South Pole-Aitken Basin’ which is still a mystery among space scientists and by sending space probe there is a historical achievement.

About Chang’e-4 Mission

Chang’e 4 mission is the China’s lunar fourth mission in series which is being named after the Chinese moon goddess. It follows the success of the Chang’e-1, Chang’e-2 and Chang’e-3 missions in 2007, 2010 and 2013. The launched mass of Chang’e-4 spacecraft was around 3,780 kg while the lander has a mass of around 1,200 kg and the rover has a mass of 140 kg. The mission is made up of two distinct elements namely the lander and the rover and also consists of relay satellite. The lander is equipped with a radioisotope thermoelectric generator (RTG) to power the lunar operations. The energy generated will be used to power the scientific payload to seven instruments and cameras. The rover will explore the surface of the moon after departing the lander and is equipped with a solar panel to power the vehicle during the mission. The landing site of the Chang’e-4 is the Von Karman crater in the South Pole-Aitken basin. It covers nearly a quarter of the moon’s surface.

About Chandrayaan-2 Mission

Chandrayaan-2 is India’s second Moon mission after Chandrayaan-1. It will be launched from Satish Dhawan Space Center at Sriharikota on-board GSLV Mk-III on 15th July 2019. It will be injected into an earth parking 170 x40400 km orbit. Chandrayaan-2 mission consists of three elements namely the Rover, the Lander and the Orbiter. When it will land on the Moon, the lander will separate from the Orbiter and then perform a series of complex manoeuvres comprising of rough braking and fine braking. Imaging of the landing site region prior to landing will be done for finding safe and hazard-free zones. On 6 September, 2019, the lander-Vikram will finally land near South Pole of the moon. Subsequently, Rover will roll out and carry several experiments on the surface of the Moon for a period of 1 lunar day which is equal to 14 Earth days. Further, Orbiter will continue its mission for duration of one year.

Mostly it is said that both the missions so far has the same objectives.

Chang’e-4 and Chandrayaan-2 Mission: Objectives

The objectives of Chang’e-4 are as follows:

– To measure the chemical compositions of lunar rocks and soils.

– To measure the temperature at the lunar surface.

– Chang’e-4 consists of low-frequency radio astronomical observation.

– To survey the terrain and land reforms.

– To detect the mineral composition and measuring the neutron radiation and neutral atoms to study the environment on the far side of the moon.

– To study the cosmic rays.

The objective of Chang’e-4 was also to expose the lunar mantle which is the region just below the moon’s crust but above the core.  The main aim is to learn more about the early solar system, lunar activity, how moon was formed and also how Earth was formed.

The objectives of Chandrayaan-2 Mission are as follows:

• The primary objective of Chandrayaan-2 is to demonstrate the ability to soft-land on the surface of the Moon and to operate a rover on the surface.
• To study the surface of the moon.
• To study the density of the electrons in the Moon’s ionosphere that is the uppermost part of the atmosphere that is ionised by radiation. To identify or to find out the minerals and indicators of hydroxyl and water molecules.

So, we can say that scientific goals of Chandrayaan-2 is to study lunar topography, mineralogy, elemental abundance, the lunar exosphere and signatures of hydroxyl and water ice.

The Chandrayaan-2 mission is completely an indigenous as all payloads and all parts are developed by India.

How Chang’e -4 is different from Chandrayaan-2?

• Chandrayaan-2 will have an Orbiter which will go around the moon while Chang’e-4 will use relay satellite to halo orbit that is to orbit an empty point in space at the L2 Lagrange Point.
• Chang’e-4 consists of 4 payloads namely relay satellite, orbiting microsatellite, lander and rover. The relay satellite work is to perform radio astronomy; lander and Yutu-2 rover will study the geophysics of the landing zone. Whereas Chandryaan-2 consists of three payloads namely the lander, the rover and the orbiter.
• Chang’e-4 carries international payloads which were developed by Germany, Sweden, the Netherland and Saudi Arabia. But Chandrayaan-2 mission is completely indigenous mission that is completely developed in India only.
• Spacecraft properties of Chang’e-4: Launch mass: Lander- 1200 kg and Rover 140 kg.
• Spacecraft properties of Chandrayaan-2: Launch mass Combined: 3,877 kg. Also, Payload mass: Orbiter- 2,379 kg, lander-1,471 kg and rover- 27 kg.

Chang’e-4 Lunar Lander results: After few hours of landing on 3rd January, 2019, the temperature of biosphere’s was adjusted to 24 degree Celsius and the seeds were watered. Further, on 15 January, 2019, it was reported cottonseed, rapeseed and potato seeds had sprouted but images of cottonseed were released. And on 16 January the experiment was terminated due to drop in the external temperature. Therefore, the experiment was terminated after nine days instead of 100 days but valuable information was obtained. On the other side lunar rover will reveal how solar wind interacts with the lunar surface and help in determining the process behind the formation of lunar water.

On a concluding note we can say that both China and India are competing to race ahead in the space exploration with targeting Chandrayaan-2 mission and other space mission in coming years. Like China, India also developed its own indigenous GPS. Chandryaan-2 mission is completely indigenous mission of India which itself is an achievement. Best wishes to Chandrayaan-2, the second India’s moon mission.

 Source:- Jagran Josh