Chandrayaan 3 - (Design, Exploration, Organisations, and Companies involved)(Teachers' special)

In continuation of our blog on Chandrayaan Mission, short details of India's Chandrayaan 1, Chandrayaan 2 and Chandrayaan 3 were given. The sharp detail of Chandrayaan 3 was given before its launch. Now Chadrayaan 3 has been launched successfully by ISRO on the surface of Moon on 23rd August at 6.03 pm. Further details of Chandrayaan 3 for the benefit of students and teachers are given below:

The spacecraft launched to the moon on July 14, 2023, at 2:35 p.m. local time from the Satish Dhawan Space Center in Sriharikota, India atop the medium-lift Launch Vehicle Mark-III (LVM3) rocket. Chandrayaan-3 successfully landed near the moon's south pole on Aug. 23, 2023, at 6:03 p.m. India Standard Time.

The mission called for a propulsion module to ferry the Chandrayaan-3' Vikram' lander and the solar-powered rover named 'Pragyan' rover together to the south pole of the moon.

The Lander Vikram will explore the following on the lunar surface:

• Chandra's Surface Thermophysical Experiment (ChaSTE) to measure thermal conductivity and temperature on the surface;

• Instrument for Lunar Seismic Activity (ILSA) to detect moonquakes;

• Langmuir Probe to estimate the density and variation of plasma, or superheated gas, in the moon's environment;

• A Laser Retroreflector Array (from NASA) to measure distances using laser ranging.

The rover 'Pragyan', "is a rectangular chassis mounted on a six-wheel rocker-bogie wheel drive assembly. The rover sends its communications to Earth through the lander. Rover instruments include:

• Alpha Particle X-ray Spectrometer (APXS) to look for elements in the lunar soil and rocks;

• Laser Induced Breakdown Spectroscope (LIBS) to examine the chemical and elemental composition of the lunar surface.

The lander and rover will collect science on the surface for 14 Earth days (a single day on the moon)

The major ISRO Centres/units involved in the design, development, testing and realization of the CH-3 mission include

• U R Rao Satellite Centre, URSC, Bengaluru

• Vikram Sarabhai Space Centre, VSSC, Trivandrum

• Liquid Propulsion Systems Centre, LPSC Trivandrum & Bangalore

• ISRO Satellite Tracking Centre, ISTRAC, Bangalore

• Space Applications Centre, SAC, Ahmedabad

• Laboratory for Electro-Optics Systems, LEOS, Bengaluru

• ISRO Inertial Systems Unit, IISU, Trivandrum

• ISRO Propulsion Complex, IPRC, Mahendragiri

• Satish Dhawan Space Centre, SDSC-SHAR

• National Remote Sensing Centre (NRSC), Hyderabad

• Physical Research Laboratory, PRL

• Space Physics Laboratory, SPL

• `The U R Rao Satellite Centre (URSC) serves as the lead centre for conceptualizing, designing, developing, testing realizing, and operationalizing satellites. Experts at URSC meticulously design, test, and certify the spacecraft's structure. Further, to ensure the spacecraft's survival in extreme temperature variations in space, thermal engineering experts maintain the temperature of different parts within specified limits, using various sensors for monitoring. The thermal protection system for CH-3 is contributed by URSC and Vikram Sarabhai Space Centre (VSSC). Various mechanisms required for payload systems, Rover ramp deployment, antenna deployment, etc. and the development of Lander’s legs were carried out at URSC, while pyro systems for deployment were provided by VSSC. These elements collectively form the mechanical subsystems of the spacecraft.

• The electronic subsystems of the satellite, are powered by energy generated by solar panels and stored in batteries. Power system engineers at URSC estimate and provide suitable power generation and distribution systems. VSSC provided solar panel substrates for CH-3. Communication engineers design, test, and deliver sophisticated communication subsystems, which serve as the link between various modules of CH-3 and the ground station.

• The satellite's orientation in space is determined by sensors such as sun sensors, star sensors, laser-based altimeters and velocimeters, which were provided by the Laboratory for Electro-optics Systems (LEOS). Space Applications Centre (SAC) provided the CH-3 Lander Imager cameras, Ka-band altimeter, hazard avoidance sensors and Rover imagers along with their data processors.

• Inertial elements such as wheels, accelerometers, and gyroscopes, which provide attitude and velocity information as well as correction of attitude errors, were delivered by ISRO Inertial Systems Unit (IISU).

• Further, all these systems are controlled and monitored by an onboard computer. Engineers with expertise in Control electronics and Digital electronics sub-systems contribute to the Attitude & Orbit Control Systems, Onboard Computers and different software catering to Navigation, Guidance and control, baseband telemetry, telecommand, data handling and storage functions.

• Once the spacecraft is deployed by the Launch Vehicle, it is the responsibility of tracking and mission engineers to ensure on-orbit operations. Tracking expertise is offered initially by SDSC-SHAR, Sriharikota and later by ISRO Tracking and Command Network, ISTRAC, Bengaluru. In interplanetary missions such as the Mars Orbiter Mission (MOM), Chandrayaan-2 (CH-2) or Chandrayaan-3 (CH-3), they occupy the driving seats during orbit insertion or final landing phases.

• Once placed into the orbit, the satellite experiences a constant drag and drifts towards the earth or celestial body that it orbits. The propulsion system is used for restoring the satellite to its orbit. Propulsion engineers offer dedicated modules for the purpose, along with the propellants. While the Liquid Propulsion Systems Centre (LPSC), Valiamala offers the engines, thrusters, and valves with associated electronics, LPSC, Bengaluru realizes the propulsion system comprising propellant tanks, control components and sensors. The engines and thrusters are all tested at the dedicated facilities at ISRO Propulsion Complex (IPRC), Mahendragiri.

• For CH-3, the integrated hot test with propulsion, sensors, Navigation, Guidance & Control and flight software was conducted at SDSC-SHAR, Sriharikota. National Remote Sensing Centre (NRSC), Hyderabad supported the ground-testing of on-board sensors with references and aerial imaging. The Indian Air Force provided a helicopter for the integrated sensors and navigation testing called the Integrated Cold Test at Chitradurga.

• Several Lander drop tests with different touch-down conditions, simulating the lunar environment, were conducted at URSC. The mechanical hardware was mainly provided by Hindustan Aeronautics Limited (HAL), with the Titanium Tanks delivered by Bharat Heavy Electricals Limited (BHEL). Further, a large number of private firms have also contributed to CH-3, in terms of mechanical and electronic fabrication. Those contributed to mechanical systems include DUCOM Aerospace, Smart Technologies, Artha Technologies, Multi Teck Engineering Solutions SLN CNC Tech, Southern Electronics, Systems control technology solutions, and Avasarala Technologies while those for electronic systems include Ananth Technologies, Centum Electronics, Data Patterns, Kaynes, Keltron, Newtech Solutions, etc.

• The integration and testing of each subsystem are conducted rigorously to ensure functionality and reliability. Dedicated teams of engineers work on the Assembly, Integration, Testing and Checkout of subsystems to create a fully functional spacecraft, ready to be integrated with the launch vehicle. These activities for CH-3 were undertaken at URSC.

Know about the companies behind India's historic Moon mission:

Larsen and Toubro (L&T)

L&T supplied various components for the spacecraft, including the heat shield, the propulsion system, and the landing gear.

Hindustan Aeronautics Limited (HAL)

HAL manufactured the Vikram lander, which is part of the spacecraft that will land on the moon.

Bharat Heavy Electricals Limited (BHEL)

BHEL supplied the power system for the spacecraft.

Paras Defence and Space Technologies

Paras Defence supplied the navigation system for the spacecraft.

Godrej Aerospace

Godrej Aerospace is an Indian aerospace company. It has been involved in the development of several components for the Chandrayaan-3 mission, including the lander's heat shield and the rover's landing gear.

MTAR Technologies

MTAR Technologies is an Indian aerospace and defense company. It has manufactured several components for the Chandrayaan-3 mission, including the lander's propulsion system and the rover's navigation system.

Ananth Technologies

Ananth Technologies is an Indian space technology company. It has developed several sensors for the Chandrayaan-3 mission, including the lander's camera and the rover's proximity sensor.

Sri Venkateswara Aerospace

Sri Venkateswara Aerospace is an Indian aerospace company. It has manufactured several structural parts for the Chandrayaan-3 mission, including the lander's legs and the rover's chassis.

Midhani

Midhani is an Indian engineering company. It has supplied critical alloys for the Chandrayaan-3 mission, including the lander's heat shield and the rover's wheels.

Himson Industrial Ceramic

Himson Industrial Ceramic is an Indian ceramic company. It has supplied components to safeguard the equipment of the Chandrayaan-3 mission from extreme temperatures.

Indian Space Research Organisation (ISRO)

ISRO is the Indian government agency responsible for space research and exploration. ISRO was responsible for the overall planning and execution of the Chandrayaan-3 mission under the Chairmanship of Shri S. Somnath.

The overall specifications for Chandrayaan-3 are provided below:

Parameters and Specifications

1. Mission Life (Lander & Rover) -

One lunar day (~14 Earth days)

2. Landing Site (Prime)-

4 km x 2.4 km 69.367621 S, 32.348126 E

3. Science PayloadsLander:

1. Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA)

2. Chandra’s Surface Thermophysical Experiment (ChaSTE)

3. Instrument for Lunar Seismic Activity (ILSA)

4. Laser Retroreflector Array (LRA) Rover:

5. Alpha Particle X-Ray Spectrometer (APXS)

6. Laser-Induced Breakdown Spectroscope (LIBS) Propulsion Module:

7. Spectro-polarimetry of HAbitable Planet Earth (SHAPE)

4. Two Module Configuration

1. Propulsion Module (Carries Lander from launch injection to Lunar orbit)

2. Lander Module (Rover is accommodated inside the Lander)

5. Mass

1. Propulsion Module: 2148 kg

2. Lander Module: 1752 kg including Rover of 26 kg

3. Total: 3900 kg

6. Power generation

1. Propulsion Module: 758 W

2. Lander Module: 738W, WS with Bias

3. Rover: 50W

7. Communication

1. Propulsion Module: Communicates with IDSN

2. Lander Module: Communicates with IDSN and Rover. Chandrayaan-2 Orbiter is also planned for contingency link.

3. Rover: Communicates only with Lander.

8. Lander Sensors

1. Laser Inertial Referencing and Accelerometer Package (LIRAP)

2. Ka-Band Altimeter (KaRA)

3. Lander Position Detection Camera (LPDC)

4. LHDAC (Lander Hazard Detection & Avoidance Camera)

5. Laser Altimeter (LASA)

6. Laser Doppler Velocimeter (LDV)

7. Lander Horizontal Velocity Camera (LHVC)

8. Micro-Star sensor

9. Inclinometer & Touchdown sensors

9. Lander ActuatorsReaction wheels –

4 nos (10 Nms & 0.1 Nm)

10. Lander Propulsion SystemBi-

Propellant Propulsion System (MMH + MON3), 4 nos. of 800 N Throttleable engines & 8 nos. of 58 N; Throttleable Engine Control Electronics 11. Lander Mechanisms

1. Lander leg

2. Rover Ramp (Primary & Secondary)

3. Rover

4. ILSA, Rambha & Chaste Payloads

5. Umbilical connector Protection Mechanism,

6. X- Band Antenna

12. Lander Touchdown specifications

1. Vertical velocity: ≤ 2 m / sec

2. Horizontal velocity: ≤ 0.5 m / sec

3. Slope: ≤ 120