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Chandrayaan-3

Mar 14, 2024

Non-EO

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ISRO

Chandrayaan-3 was the third lunar mission of the Indian Space Research Organisation (ISRO), launching on the 14th July 2023 and landing on the Moon on 23rd August 2023. The mission demonstrated the first soft landing in the Southern Polar region of the Moon, as well as placing India as the fourth country to land on the Moon.

Quick facts

Overview

Mission typeNon-EO
AgencyISRO
Launch date14 July 2023

Related Resources

Chandrayaan-1Chandrayaan-2


 

Summary

Mission Capabilities

Chandrayaan-3 was the follow-on mission to Chandrayaan-2, and consisted of a Propulsion Module (PM), a Lander Module (LM), and a Rover housed inside the LM. The PM carried one instrument, the Spectro-Polarimetry of Habitable Planet Earth (SHAPE) sensor, which made spectral and polarimetric measurements of Earth from a lunar orbit.

The LM carried three instruments: the Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere - Langmuir Probe (RAMBHA-LP), Chandra’s Surface Thermo-physical Experiment (ChaSTE), and the Instrument for Lunar Seismic Activity (ILSA). RAMBHA-LP was a Langmuir probe that measured plasma density around the landing site of the LM. ChaSTE was a penetrating temperature probe that gathered temperature profiles of the lunar surface, and ILSA was an accelerometer instrument that measured seismic activity on the Moon.

The Rover carried two instruments: the Alpha Particle X-ray Spectrometer (APXS), and the Laser Induced Breakdown Spectroscope (LIBS). APXS was a spectrometer that derived chemical and inferred mineral compositions of the lunar surface, using the roving ability of the Rover to investigate lunar soil and rocks around the Chandrayaan-3 landing site. LIBS was a spectroscopic device that aimed to generate qualitative and quantitative elemental analyses, and infer mineralogical compositions of the lunar surface.

 

Mission Overview

Chandrayaan-3’s mission was operated in three phases: The Earth-centric phase, Lunar Transfer Phase, and Moon Centric Phase. The Earth Centric Phase saw the launch of Chandrayaan-3, and its deliverance to a Geostationary Transfer Orbit (GTO). After which the spacecraft separated from the launcher and Chandrayaan-3’s PM fired its thrusters in a series of Earth-bound manoeuvres to increase its orbit.

The Lunar Transfer Phase involved a Translunar Injection (TLI), whereby Chandrayaan-3 began its trajectory for the Moon after a final perigee burn by the PM. This final Earth-bound manoeuvre sent Chandrayaan-3 to the Moon in a four-day journey.

Chandrayaan-3’s Moon-centric Phase began with lunar insertion, followed by de-boosting to decrease and circularise its orbit around the Moon. The PM separated from the LM followed by further deceleration by the LM to descend to the lunar surface. Once Chandrayaan-3 successfully landed on the Moon, the Rover deployed from LM and the mission began gathering scientific data. The LM and Rover operated on the lunar surface for one lunar day, equivalent to 14 Earth days.

Space and Hardware Components

Chandrayaan-3’s PM was based on a modified I-3K platform, with a dry mass of 448 kg that carried 1696 kg of propellant. The module exceeded its three-month design life, using fuel reserves to move back to an Earth orbit following the mission’s completion, in order to make observations in support of future lunar missions.

The LM ferried 1750 kg of mass to the lunar surface, including the 26 kg Rover housed inside. The six-wheeled ‘Pragyan’ Rover is an iteration of the rover from Chandrayaan-2. The LM communicated with the Indian Deep Space Network (ISDN) on Earth, the Chandrayaan-2 orbiter, and the Rover. The PM and LM communicated over S and X band to ground stations on Earth, which supported the mission throughout its entire duration.

 

Overview

Chandrayaan-3 marks India's third lunar exploration mission, dedicated to demonstrating a soft landing on the lunar surface and roving on the lunar terrain. The name refers to ‘Chandra’ (Moon) and ‘Yaan’ (craft). 1) 2)

The mission followed on from Chandrayaan-2, and demonstrated end-to-end capabilities in the safe landing and roving on the lunar surface. The mission developed and demonstrated new technologies in support of ISRO’s future interplanetary missions. The Lander Module (LM) deployed the Rover, which aimed to perform in-situ chemical analyses of the lunar surface over its operational lifetime of a lunar day (14 Earth days). 3)

Chandrayaan-3 became the first mission to demonstrate a soft landing on the unexplored Southern Polar region of the Moon, with India becoming the fourth country to ever land on the Moon.  India’s lunar journey began with Chandrayaan-1 in October 2008, which focused on the South Pole of the Moon. The mission consisted of an orbiter with 11 payloads designed to study mineral composition, water-ice at the poles, chemical composition of rocks, and to gain understanding of the Moon’s evolution. As well as capturing global imagery of the Moon, the mission made the groundbreaking discovery of finding traces of water on the lunar surface, as well as Magnesium, Aluminum and Silicon.  4)

Following on from the success of Chandrayaan-1, India launched their second lunar mission in July 2019, Chandrayaan-2. This mission was designed to provide continuity to Chandrayaan-1, this time with a Lander and Rover to demonstrate a soft landing on the Moon and conduct in-situ experiments on the surface. The Lander lost contact with the just 2.1 km above the lunar surface before the planned touchdown. The Chandrayaan-2 orbiter is still operational and supported Chandrayaan-3 as a backup for communications. 5)

India launched its third mission, Chandrayaan-3, in July 2023 to succeed Chandrayaan-2 and complete its unfinished task of achieving a soft landing on the Moon. Chandrayaan-3 was expected to provide valuable insights into the Moon’s origin, evolution, potential for resources, and to develop India’s space capabilities as a leading player in the global space race. 6)

The mission objectives of Chandrayaan-3 were:

  • To demonstrate safe and soft Landing on Lunar Surface
  • To demonstrate Rover roving on the moon and
  • To conduct in-situ scientific experiments.
Figure 1: Chandrayaan-3 in the clean room (Image credit: ISRO)

A brief history of the Chandrayaan missions to the Moon, and an introduction to Chandrayaan-3 with its objectives, payloads, and preparation video can be viewed through this link.

Spacecraft

The Chandrayaan-3 spacecraft consisted of a Propulsion Module (PM) coupled with a Lander Module (LM), the latter which houses a lunar rover that aimed to develop and demonstrate novel technologies for interplanetary missions. The PM carried the LM and rover from a lunar injection orbit into a 100 km altitude lunar orbit before the LM’s descent to the surface.

Propulsion Module (PM)

The primary function of the PM was to carry the LM from a launch vehicle injection orbit down to a low altitude before separation. PM was based on the ISRO I-3K (INSAT 3000) platform, which is also shared by ISRO’s INSAT-3A (Indian National Satellite) as well as NISAR (NASA-ISRO Synthetic Aperture Radar) missions.

Table 1: PM Specifications 2)

Parameter

Specification

Orbit

From 170 km x 36500 km Earth orbit to lunar polar orbit

Platform

Modified I-3 K

Dry Mass (kg)

448.62

Propellant Mass (kg)

1696.39

Total PM Mass (kg)

2145.01

Power Generation (W)

738 (assuming bias and during Summer Solstice)

Communication

S-Band

Attitude Sensors

CASS (Coarse Analogue Sun Sensor),  IRAP (Inertial Reference unit and Accelerometer Package), Micro star sensor

Propulsion

Bi-Propellant (Monomethylhydrazine [MMH] and 3% Mixed oxides of Nitrogen [MON3])

 

Lander Module (LM) ‘Vikram’ and Rover ‘Pragyan’

The LM was nicknamed ‘Vikram’, sanskrit for ‘valour’, and the Rover was named ‘Pragyan’, sanskrit for ‘wisdom’. The Chandrayaan-3 Vikram lander was an improved version of the Chandrayaan-2 Vikram lander, with more fuel and one less throttleable engine. 3)

The Pragyan Rover was a new iteration of the Rover onboard Chandrayaan-2; a six-wheeled solar-powered vehicle that deployed from the LM. Pragyan was capable of travelling up to 500 m at 1 cm per second. Differential steering controlled the Rover’s motion, with each wheel driven by independent brushless electric motors, cushioned by a rocker-bogie suspension system.

Figure 2: Chandrayaan-3 Vikram Lander (Image credit: ISRO)

Table 2: LM and Rover mission and hardware specifications. 2)

 

Lander

Rover

Design Life

1 Lunar day (14 Earth days)

1 Lunar day

Mass (kg)

1749.86 with Rover

26.00

Power (W)

738 (at Winter Solstice)

50

Payloads

3

2

Dimensions (mm3)

2000 x 2000 x 1166

917 x 750 x 397

Communication

Indian Deep Space Network (ISDN), Chandrayaan-2 Orbiter, Rover

LM

Landing site

69.367621 S, 32.348126 E

 

The LM housed a bi-propellant propulsion system to power its descent to the surface, consisting of Monomethylhydrazine (MMH) and Mixed Oxides of Nitrogen (MON-3). The craft had four throttleable engines each providing 800 N of thrust, and eight further engines each providing 58 N. 3)

The LM housed a suite of sensors onboard to guide its descent to the lunar surface, including the Laser Inertial Referencing and Accelerometer Package (LIRAP); Ka-Band Altimeter (KaRA); Lander Position Detection Camera (LPDC); LHDAC (Lander Hazard Detection & Avoidance Camera); Laser Altimeter (LASA); Laser Doppler Velocimeter (LDV); Lander Horizontal Velocity Camera (LHVC); a Micro Star sensor; and Inclinometer and Touchdown sensors.

Figure 3: Pragyan Rover diagram (Image credit: ISRO)

 

Launch Vehicle Mark 3 (LVM3)

LVM3 is ISRO’s largest and heaviest operational launch vehicle, with a successful flight heritage marking its fourth operational flight with Chandrayaan-3. The launcher carried Chandrayaan-3 to a Geostationary Transfer Orbit (GTO) of 36,500 km x 170 km. LVM3’s stages include two S200 strap-on motors, a liquid core stage, a cryogenically-cooled upper stage, and a five metre oversized payload fairing (OPLF).

Table 3: LVM3 stage specifications. 2)

Stage

Strap-Ons (2 x S200)

Core (L110)

Upper (C25)

Length (m)

26.2

21.4

13.5

Propellant Type

Solid - HTPB (Hydroxyl-terminated polybutadiene)

Liquid - UH25 (Unsymmetrical Dimethylhydrazine) + N2O4 (Nitrogen Tetroxide)

Cryo - LH2 (Liquid Hydrogen) + LO (Liquid Oxygen)

Propellant Mass (kg)

204.5 (each)

115.8

28.6

 

 

Figure 4: LVM3 preparing for the launch of Chandrayaan-3 (Image credit: ISRO)

 

Mission Phases

1. Earth Centric Phase

Phase one of Chandrayaan-3’s mission consisted of pre-launch procedures, the launcher’s liftoff and ascent, and a series of Earth-bound manoeuvres to increase its orbit away from Earth.

Phase 1 Timeline

  • 14th July 2023: Chandrayaan-3 launched from the Satish Dhawan Space Centre in Sriharikota Range (SDSC SHAR), India, onboard ISRO’s LVM3 (Launch Vehicle Mark-3). The time of launch was 09:05 UTC.

 

Figure 5: LVM3 lifting off from SDSC SHAR carrying Chandrayaan-3 (Image credit: ISRO)

A little over 15 minutes later, at 09:21 UTC, Chandrayaan-3 separated from LVM3 after being placed in a parking orbit of approximately 550 km in altitude.

  • 15th July 2023: The first orbit-raising manoeuvre is performed by ISRO’s Telemetry Tracking and Command Network (ISTRAC), placing the spacecraft in a highly elliptical 41762 km (apogee) x 173 km (perigee) orbit. Three further Earth-bound perigee firings were completed on the 17th, 22nd and 25th of July. 3)

https://twitter.com/i/status/1679785630501588993

 

2. Lunar Transfer Phase

Phase two for Chandrayaan-3 involved the spacecraft leaving Earth’s orbit and starting a trajectory for the Moon, with a translunar injection (TLI). The TLI allowed the spacecraft to escape Earth’s gravitational pull through a number of precisely timed burns from the PM when at perigee (closest point to Earth in elliptical orbit).  2) 8)

The series of Earth-bound manoeuvres placed Chandrayaan-3 in an increasingly elliptical orbit while building speed for the TLI. The PM fired its thrusters at perigee, where the spacecraft also received a gravitational slingshot from the Earth. This acceleration was sufficient to send Chandrayaan-3 into a Translunar orbit, where its apogee extended far enough that it could be captured by the Moon’s gravity and enter a lunar orbit. It took four days for Chandrayaan-3 to reach the Moon after its final Earth-bound manoeuvre. 9)

Timeline

  • 1st August 2023: TLI is performed, placing Chandrayaan-3 into 288 km x 369,328 km lunar orbit.
Figure 6: Chandrayaan-3’s trajectory to the Moon, with the TLI manoeuvre (Image credit: ISRO)

 

3. Moon Centric Phase

The third phase of Chandrayaan-3 began with a Lunar-Orbit Insertion (LOI), during which the spacecraft transitioned from its translunar orbit as it was captured by the gravitational influence of the Moon. Several Moon-bound manoeuvres were required to decrease the eccentricity of the lunar orbit, which were the product of several retrograde (opposing direction of motion) burns performed at perilune (closest point to the Moon). These manoeuvres have the opposite effect to the Earth-bound manoeuvres, as its orbit circularises from a decreased velocity.

Phase three followed with PM and LM separation, followed by de-boosting and a pre-landing phase for the LM before it touched down on the lunar surface. Once landed, the LM and onboard Rover began their one lunar day normal phase in which they performed experiments on the surface.

Phase 3 Timeline

  • 5th August 2023: Chandrayaan-3 is successfully inserted into lunar orbit, of 164 km (apolune) x 18,074 km (perilune). 3) 10)

Here is a video footage of Chandrayaan-3 during lunar orbit insertion.

The PM then performs a series of burns to reduce Chandrayaan-3’s orbit, bringing itself closer to the lunar surface ready to detach from the LM.

Table 4: LOI PM retrograde burns timeline

Moon-bound manoeuvre date (August 2023)

Orbit achieved (apolune x perilune) [km]

5th (LOI)

164 x 18,074

6th

160 x 4313

9th

174 x 1437

14th (orbit circulation)

151 x 179

16th

153 x 163

 

  • 17 August 2023: Chandrayaan’s LM separates from the PM, and will be followed by deboosting for lunar descent. The first de-boosting finishes on the 19th August placing LM in a 113 km x 157 km orbit.
  • 23rd August 2023: Chandrayaan-3’s lander module successfully touched down on the Moon’s Southern polar region following a powered descent. Chandrayaan-3 sends its first message after landing: “India, I reached my destination and you too”. The entire landing can be watched here. 3)

The landing site of Chandrayaan-3 is located at 69.367621 °S, 32.348126 °E. The chosen landing site of Chandrayaan-3 was of eight considered sites, of which two sites were decided (primary and alternate/backup landing site). The landing site of Chandrayaan-3 is approximately 42 km away from the planned landing site of Chandrayaan-2, and lies between the Manzius U and Boguslawsky craters. The planned landing sites are highland regions with relatively flat terrains. 11)

The selection of this landing site was very carefully decided, and was governed by many factors among regional and local topography for safe landing and roving, illumination, temperature, composition, geology, and local environment for science.

Figure 7: (a) Proposed landing sites (S-1 to S-8) for Chandrayaan-3 (b) Selected primary (PLS) and alternate (ALS) landing sites. Imagery was acquired by NASA’s Lunar Reconnaissance Orbiter (LRO) (Image credit: NASA, 11)
  • 24th August 2023: Chandrayaan-3’s Rover descended the LM’s ramp onto the lunar surface.

Animation depicting the LM’s ramp and Rover deployment, followed by stunning camera visuals from the LM as the Rover ‘Pragyan’ roves about the surface and demonstrates an in-place turn can be viewed here.

With the Pragyan Rover, India will carry out the first ever in-situ experiments at a high-latitude location on the Moon. 4)

 

Chandrayaan-3 experiments and beyond

Timeline

  • 27th August 2023: LM ChaSTE (Chandra’s Surface Thermo-physical Experiment) instrument makes its first observations, measuring the temperature profile of the lunar regolith around the South Pole to gain understanding of the thermal behaviour of the lunar surface. ChaSTE gathers the first such profile for the lunar South Pole. 12)
Figure 8: Temperature variations of lunar surface with depth, measured by ChaSTE’s temperature probe and its controlled penetration mechanism. (Image credit: ISRO)
  • 28th August 2023: The lunar rover confirms the presence of Sulphur on the lunar surface through in-situ experiments with LIBS (Laser Induced Breakdown Spectroscope). These mark the first ever in-situ measurements of the composition of the lunar surface near the South Pole, with its feat not achievable by instrumentation onboard the orbiters. 13)
Figure 9: LIBS emission spectrum of the lunar surface, revealing the presence of Aluminium, Sulphur, Calcium, Iron, Chromium, and Titanium. Further measurements revealed Manganese, Silicon, and Oxygen.
  • 30th August 2023: The Pragyan Rover captures stunning Anaglyph of the Vikram Lander on the lunar surface. This anaglyph highlights terrain topography in 3D, using composite imagery from the Rover’s NavCam imagers. 14)
Figure 10: The Pragyan Rover gathers stereo imagery of the Vikram Lander on the lunar surface to create an anaglyph. Three channel imagery acquired by Pragyan consisted of a red channel image from the (suitably named) NavCam-Left, and an image of both blue and green channels from NavCam-Right. The observed parallax between images creates a stereo effect that can be observed through 3D glasses. (Image credit: ISRO)
  • 31st August 2023: Vikram’s ILSA (Instrument for Lunar Seismic Activity) payload listens to movements around its landing site. ILSA is the first Micro Electro Mechanical Systems (MEMS) based instrument on the Moon, and since deployment has recorded vibrations due to the Rover and other payloads. ILSA’s objective is to measure seismic activity from moonquakes, impacts, and artificial events.
Figure 11: ILSA records vibrations in the lunar surface due to the Rover’s movement on August 25th, 2023 (Image credit: ISRO)
Figure 12: ILSA detects potential natural seismic activity on the lunar surface on August 26th, 2023. The source of the event in question is under investigation (Image credit: ISRO)

Vikram also makes its first in-situ measurements of the surface-bound lunar plasma over the Southern polar region, with RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere - Langmuir Probe). The initial assessment indicates a sparse distribution of plasma over the lunar surface, between five to 30 million electrons per cubic metre. RAMBHA-LP observations are important for investigating the charging of the near-lunar surface region, particularly in response to space weather. 15)

Figure 13: Shadow of RAMBHA-LP and Rover on the lunar surface taken by Vikram (Image credit: ISRO)
Figure 14: Preliminary measurements of plasma density around the near-surface region (Image credit: ISRO)
  • 3rd September 2023: Vikram performs a ‘Lander hop experiment’ in which the module lifted off from its landing spot and then touched down again. This feat was done to demonstrate the LM’s capability to lift off from the lunar surface, which in future may be used to return samples from the Moon to India. The experiment was not a part of the mission plan, but a ‘bonus objective’ executed by the LM’s onboard computer, which validated the lander’s attitude control, structural integrity, and intelligence while paving the way for future missions.

Chandrayaan-3 LM conducted a ‘hop experiment’ in which it lifted off from its landing site and flew 50 metres in ten seconds before touching back down. A video clip can be viewed through this link.

  • 4th September 2023: The LM and Rover enter sleep mode, and plan to wake on the 22nd September. 3)
  • 22nd September 2023: ISRO attempts to establish communication with the LM and Rover, but are unsuccessful and fear the harsh cold lunar nights (14 Earth days) have affected their batteries. The LM and Rover were designed to survive for one Lunar day, as ISRO already knew of the potential threat of the lunar night. 16)

Former Chandrayaan mission scientist, Manish Purohit, states "Vikram and Pragyan were expected to wake up after braving the harsh lunar nights where temperatures dip to minus 180 degrees Celsius. The chances of revival were totally dependent on the batteries surviving the long lunar nights. Currently, the team is continuously trying to get a connection to the lander and the rover, and waiting for the temperatures to rise as the lunar day progresses. Since we do not have any radioisotope heating unit, we can only wait and watch."

Regardless, the Chandrayaan-3 mission is deemed a complete success as its mission objectives have been met.

  • 4th December 2023: Chandrayaan-3’s PM moves from lunar orbit into an Earth orbit. The PM’s primary objective was to carry the LM from GTO to a circular lunar polar orbit and separate from it. The satellite’s Spectro-polarimetry of HAbitable Planet Earth (SHAPE) instrument was planned to operate for three months during its design life. However due to the precise orbital injection by LVM3 and optimal burns, the PM finished its first month of operations with over 100 kg of fuel in reserve. This presented the opportunity to gather additional information for future lunar missions and demonstrate operations for a sample return mission. 17)

ISRO decided to re-insert the PM to a suitable Earth orbit in order to continue the operation of SHAPE for Earth observation. The outcomes of the PM’s return manoeuvers include the planning and execution of returning from Moon to Earth; development of a software module to plan such a manoeuver; planning a gravity-assisted flyby; avoiding uncontrolled crashing of the PM on the lunar surface at its end of life (EOL) and adhering to the no debris-creating requirement.

 

Sensor Complement

PM Payload (SHAPE)

Spectro-polarimetry of Habitable Planet Earth (SHAPE)

SHAPE was the singular instrument onboard Chandrayaan-3’s PM, and made spectral and polarimetric measurements of Earth from a lunar orbit. The instrument characterised Earth’s disc-integrated spectrum and polarisation signatures at various phase angles acquired from lunar orbit. 2) 18)

Observations made from the Moon simulate the observations of exoplanets. The spectral information obtained by SHAPE provided insight on the chemical composition of the planetary atmosphere and surface, while polarimetric measurements will characterise clouds. SHAPE made observations in the Near-Infrared (NIR) waveband, from 1 - 1.7 μm.

Figure 15: Illustration of SHAPE’s observations aboard the Chandrayaan-3 Propulsion Module, and the different phase angles (φ) it will achieve as the Moon orbits Earth. (Image credit: ISRO)

SHAPE broadened our knowledge of exoplanets in reflected light, and investigated what an Earth-like exoplanet’s disc integrated spectra and polarisation look like, and how they might change with rotation and revolution. Future observations of small Earth-like exoplanets with the knowledge acquired by SHAPE will help us identify planets with habitability.

Figure 16: Annotated image of Chandrayaan-3’s SHAPE (Spectro-polarimetry of HAbitable Planet Earth) instrument (Image credit: ISRO)

The SHAPE instrument consisted of an Acousto-optic Tunable Filter (AOTF) -based dispersive element driven by a Radio Frequency (RF) source and two Indium Gallium Arsenide detectors. SHAPE was designed by the Space Astronomy Group (SAG) of the U. R. Rao Satellite Centre (URSC), Bengaluru.

LM Payloads (RAMBHA-LP, ChaSTE, ILSA)        

RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere - Langmuir Probe)

RAMBHA-LP of Chandrayaan-3’s LM measured plasma density around the lunar surface, and investigated how it changes over a lunar day. The Langmuir probe (named after Irving Langmuir) was a device used to characterise ions and electrons (plasma). The instrument consisted of a 5 cm metallic spherical probe attached to a 1 m boom connected to the LM’s upper deck. This boom ensured the probe’s operation was unobstructed by the Lander’s body and allowed RAMBHA-LP to make observations of undisturbed lunar plasma. 2) 15)

The probe was deployed after the Lander’s touchdown with a hold-release mechanism, and detected minute return currents of the order of pico-amperes, with a dwell time of 1 ms. A sweeping bias from -12 to +12 V applied to RAMBHA-LP enabled the accurate measurement of ion and electron densities as well as their energies.

RAMBHA-LP’s development was led by ISRO’s Space Physics Laboratory (SPL) at the Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, India. 15)

ChaSTE (Chandra’s Surface Thermo-physical Experiment)

ChaSTE was a temperature probe onboard the LM that carried out measurements of the thermal conductivity and gathered temperature profiles of the near-polar lunar surface. The instrument had a controlled penetration mechanism capable of deriving temperature gradients down to 10 cm below the surface from the landing site. ChaSTE was equipped with ten individual temperature sensors to measure the thermophysical properties of a high latitude region of the Moon, for the first time. 2) 3) 12) 19)

ChaSTE was developed jointly by the Physical Research Laboratory (PRL), Ahmedabad and the Space Physics Laboratory (SPL), VSSC, and Trivandrum.

Figure 17: Illustration of ChaSTE configurations onboard the Vikram Lander (Image credit: PRL)

ILSA (Instrument for Lunar Seismic Activity)

ILSA was an instrument onboard the LM that aimed to measure seismicity around the landing site, allowing scientists to characterise moonquakes and other natural lunar phenomena, and build understanding of the lunar crust and mantle. The payload was the first instance of a micro-electro mechanical system (MEMS) used on the Moon, and consisted of six high-sensitivity accelerometers innovatively joined with Silicon micromachining. The sensing element of ILSA was a spring-mass system with comb-structured electrodes. Any vibrations that reached the instrument deflected the mass and caused a change in capacitance between electrodes, which was converted to a voltage signal. 2) 20)

ILSA was developed at the Laboratory for Electro-Optics Systems (LEOS), Bangalore, alongside private entities. ILSA’s deployment mechanism was developed by U.R. Rao Satellite Centre of Bengaluru.

 

Rover Payloads (APXS, LIBS)

APXS (Alpha Particle X-ray Spectrometer)

APXS was a spectrometer instrument onboard the Pragyan Rover with the objective to derive the chemical composition and inferred mineral compositions of the lunar surface. 2) 3)

The instrument performed spectroscopy using X-ray fluorescence with the in-situ excitation of Curium-244, which emitted both X-rays and α particles. These sources excited the target whereby the production of characteristic X-rays were emitted (through particle-induced X-ray emission [PIXE] and X-ray fluorescence [XRF]). These X-rays were then detected by the novel Silicon Drift Detector (SDD), which enabled APXS to detect all major rock forming elements such as Sodium, Magnesium, Aluminium, Silicon, Calcium, Titanium, and Iron. 21)

LIBS (Laser Induced Breakdown Spectroscope)

LIBS was a spectroscopic device with the objective to generate qualitative and quantitative elemental analyses, and infer mineralogical compositions of the lunar surface. LIBS was a spectroscopy technique that involves the analysis of material compositions through their exposure to high energy laser pulses. A laser is focused on the surface of a piece of lunar material such as rock or soil, which generates an extremely hot and localised plasma. This plasma has a characteristic spectral fingerprint unique to the elemental composition of the target. The LIBS instrument was developed at the Laboratory for Electro-Optics Systems (LEOS)/ISRO, Bengaluru. 3) 13) 22)

Ground Segment

Alongside ISRO’s Indian Deep Space Network (IDSN), Chandraayaan-3 received support from ground stations around the world, coordinated by ESA and NASA. ISRO’s 32-metre DSN tracking station in India allowed them to conduct Telemetry, Tracking and Command (TT&C) operations with the spacecraft, which was continued by other ground stations as its line of sight moved while orbiting the Earth. ESA’s Estrack DSN supports its partners with TT&C for spacecraft almost anywhere in the solar system through the ESOC mission control centre in Germany. 1) 23) 24)

ESA’s 15 m antenna in Kourou, French Guiana, tracked Chandrayaan-3 in the recent days after launch to help ensure the spacecraft suffered no issues during liftoff, and was clear to begin its Earth-bound manoeuvres. As the spacecraft accelerated away from Earth, ESA coordinated with Goonhilly Earth Station Ltd. (GES), UK to support TT&C operations alongside Kourou. Goonhilly supported Chandrayaan-3’s PM and LM simultaneously with a combination of X and S band frequencies, a vital feature of their 32 m DSN antenna, as well as supporting the LM during its operations on the lunar surface. TT&C support for the LM while on the lunar surface was crucial to ensure that science data acquired from both the Lander and Pragyan Rover were delivered safely to ISRO. Chandrayaan data from Kourou and Goonhilly was first forwarded to ESOC before passed onto ISRO.

Tracking from these two stations was supported by NASA’s and ISRO’s respective DSNs, to ensure Chandrayaan-3 was never out of sight throughout the entirety of the mission’s duration.

Figure 18: Chandrayaan-3 Ground station map, including contribution from ISRO, ESA, GES, and NASA (Image credit: ESA, 23)

 

References  

1) “India’s Chandrayaan-3 successfully lands on the Moon,” ESA, August 23 2023, URL: https://www.esa.int/Enabling_Support/Operations/India_s_Chandrayaan-3_successfully_lands_on_the_Moon

2) “LVM3-M4/Chandrayaan-3 Moon Mission Brochure,” ISRO, URL: https://www.isro.gov.in/media_isro/pdf/Missions/LVM3/LVM3M4_Chandrayaan3_brochure.pdf

3) “Chandrayaan-3,” ISRO, September 26 2023, URL: https://www.isro.gov.in/Chandrayaan3.html

4) Kumar A, Mehfuza M. “INDIA’S JOURNEY TOWARDS MOON: FROM CHANDRAYAAN-1 TO CHANDRAYAAN-3,” International Research Journal of Modernization in Engineering Technology and Science, August 2023.

5) Annadurai, Mylswami; Nagesh, G.; Vanitha, Muthayaa (28 June 2017). "Chandrayaan-2: Lunar Orbiter & Lander Mission,” 10th IAA Symposium on The Future of Space Exploration: Towards the Moon Village and Beyond, Torin, Italy, 28 June 2017, URL: https://archive.org/details/IAAFSE170602Annadurai/IAA-FSE-17-04-01-Nagesh/

6) Biswas, Som, and Srirupa Biswas. "Chandrayaan 3 and Other Moon Missions: An Update and Review." Available at SSRN 4553155 (2023).

7) Sharmila Kuthunur, “India on the moon! Chandrayaan-3 becomes 1st probe to land near lunar south pole,” SPACE.com, 23 August 2023, URL: https://www.space.com/india-chandrayaan-3-moon-landing-success

8) “What is the Translunar Injection (TLI)?,” Vajiram & Ravi, 1 August 2023, URL: https://vajiramias.com/current-affairs/what-is-the-translunar-injection-tli/64c8b68a9c96bc05cc1c1237/

9) Biesbroek R, Janin G. “Ways to the Moon,” ESA bulletin. 2000 Aug 1;103:92-9, URL: https://www.esa.int/esapub/bulletin/bullet103/biesbroek103.pdf

10) “Chandrayaan-3 Mission: Update,” ISRO, 5 August 2023, URL: https://www.isro.gov.in/Ch3_Lunar_Orbit_Insertion_Press_Release.html

11) K Durga Prasad, Megha Bhatt, Amitabh , G Ambily, Sachana Sathyan, Dibyendu Misra, Neeraj Srivastava, Anil Bhardwaj, Contextual characterization study of Chandrayaan-3 primary landing site, Monthly Notices of the Royal Astronomical Society: Letters, Volume 526, Issue 1, November 2023, Pages L116–L123, URL: https://doi.org/10.1093/mnrasl/slad106

12) “The first observations from the ChaSTE payload onboard Vikram Lander,” ISRO, September 18 2023, URL: https://www.isro.gov.in/Ch3_first_observation_ChaSTE_Vikram_Lander.html

13) “LIBS confirms the presence of Sulphur (S) on the lunar surface through unambiguous in-situ measurements,” ISRO, August 39 2023, URL: https://www.isro.gov.in/LIBSResults.html

14) “Chandrayaan-3 Image gallery,” ISRO, URL: https://www.isro.gov.in/chandrayaan3_gallery.html

15) “RAMBHA-LP on-board Chandrayaan-3 measures near-surface plasma content,” ISRO, September 18 2023, URL: https://www.isro.gov.in/Ch3_Rambha-LP_near-surface_Plasma.html

16) Radifah Kabir, “Chandrayaan-3: Why Did Vikram And Pragyan Not Wake Up At Lunar Sunrise? Know If They Will In Future,” abp live,  October 1 2023, URL: https://news.abplive.com/science/chandrayaan3-vikram-lander-pragyan-rover-did-not-wake-up-at-lunar-sunrise-will-they-wake-up-in-future-1633125

17) “Returns to home Earth: Chandrayaan-3 Propulsion Module moved from Lunar orbit to Earth's orbit,” ISRO, December 11 2023, URL: https://www.isro.gov.in/Ch3_Propulsion_Module_moved_from_Lunar_orbit_to_Earth_orbit.html

18) “Chandrayaan-3: SHAPE,” ISRO U. R. Rao Satellite Centre, 2024, URL: https://www.ursc.gov.in/shape.jsp

19) “Chandra’s Surface Thermo-physical Experiment (ChaSTE),” Physical Research Laboratory (PRL), Planetary Instrument Development Section (PIDS), URL: https://www.prl.res.in/~pids/ChaSTE.html

20) “ILSA listens to the movements around the landing site,” ISRO, September 18 2023, URL: https://www.isro.gov.in/Ch3_ILSA_Listens_Landing_Site.html

21) M. Shanmugam, S. V. Vadawale et al., “Alpha Particle X-Ray Spectrometer (APXS) On-board Chandrayaan-2 Rover - Pragyan,” Physical Research Laboratory, Ahmedabad, URL: https://arxiv.org/ftp/arxiv/papers/1910/1910.09232.pdf

22) A. S. Laxmiprasad, R. V. L. N. Sridhar, et al, “Laser Induced Breakdown Spectroscope on Chandrayaan-2 Rover: a miniaturized mid-UV to visible active spectrometer for lunar surface chemistry studies,” Laboratory for Electro-Optics Systems, Indian Space Research Organisation, Bengaluru 560 058, India, URL: https://www.currentscience.ac.in/Volumes/118/04/0573.pdf

23) “ESA ground stations support Chandrayaan-3 Moon mission,” ESA Operations, 13 July 2023, URL: https://www.esa.int/Enabling_Support/Operations/ESA_ground_stations_support_Chandrayaan-3_Moon_mission

24) “Estrack ground stations,” ESA Ground Stations, URL: https://www.esa.int/Enabling_Support/Operations/ESA_Ground_Stations/Estrack_ground_stations

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