In News:

Findings from the Chandrayaan-3 Vikram lander's "hop" experiment, published in The Astrophysical Journal in April 2026, demonstrate significant heterogeneity in the Moon's surface composition at local scales — challenging previous assumptions about lunar soil uniformity and providing India's first in-situ geotechnical data from the lunar south polar region.

The Hop Experiment:

On 2 September 2023, engineers reignited Vikram's engines to perform a short vertical hop of approximately 50 centimetres using residual propellant. The manoeuvre was initially designed to validate re-ignition capabilities for future sample-return missions, but the engine exhaust inadvertently stripped away the top three centimetres of loose lunar dust, exposing denser material beneath — providing a unique opportunity to study subsurface regolith properties at the south pole for the first time.

The Chandra's Surface Thermophysical Experiment (ChaSTE) — equipped with temperature sensors and a heating probe that penetrated the regolith — was then redeployed at the new post-hop location, measuring thermal profiles during the twilight transition (16:25–17:30 lunar local time), a slow cooling period lasting hours due to the Moon's month-long day-night cycle.

Key Scientific Findings

Two-Layer "Cake-Like" Structure

The Moon's surface at the south pole exhibits a distinct, two-layer structure within the top few centimetres — not a uniform pile of dust as previously assumed.

Upper Layer (0–6 cm) — The "Fluffy Thermal Blanket": The top layer is hyper-porous and highly cohesive, behaving like loose flour near the surface. Bulk density increases dramatically from 750 kg/m³ at the surface to 1,600 kg/m³ at a depth of just 6.5 cm — where the material becomes significantly stiffer, behaving more like damp clay.

Thermal Behaviour:ChaSTE captured a sharp temperature drop after 17:00 lunar local time, as the absence of an atmosphere allows heat to radiate rapidly into space once the Sun's rays are blocked by local shadows — demonstrating how the hyper-porous top layer functions as a critical thermal insulator.

Supporting Evidence: 3D simulations using Chandrayaan-2's OHRC (Orbiter High Resolution Camera) high-resolution imagery confirmed the regolith's layered stratigraphy.

What is Lunar Regolith?

Scientists emphasise that the Moon's surface layer is more accurately termed "lunar regolith" rather than "lunar soil" — it consists of shattered rock fragments and jagged glass-like shards formed by billions of years of micrometeorite bombardment. Unlike terrestrial soil, it lacks organic material or water-formed minerals, and its jagged, angular particles create unusual mechanical properties — high cohesion yet extreme looseness at the surface.

Why It Matters: Five Implications

• Water-Ice Storage: The hyper-porous top layer is particularly significant for trapping water-ice molecules in the subsurface — critical for assessing the viability of in-situ resource utilisation (ISRU) at lunar south polar bases.
• Future Lunar Base Planning: The dramatic density gradient within just 6.5 cm means that drilling, foundation engineering, and habitat construction at the lunar south pole will require significantly different approaches than originally modelled — directly informing NASA's Artemis programme and ISRO's own lunar ambitions.
• Rocket Plume-Surface Interaction: Understanding how engine exhaust erodes the regolith is essential for safe landing zone design for future crewed and cargo missions — preventing landing struts from sinking into loose surface material.
• Sample Return Missions: The hop experiment validates critical engine re-ignition capabilities, setting a precedent for future sample-return missions.
• Chandrayaan-4 Design Inputs: India's upcoming Chandrayaan-4 mission — designed for lunar sample collection and return — will directly incorporate these findings in its lander design and landing site selection.

In News:

The Space Commission also approved a joint moon mission with Japan called the Lunar Polar Exploration Mission. For LUPEX, ISRO is developing a different moon lander than the one it used for Chandrayaan-3

New Space Missions and Developments

• Chandrayaan-4 (Moon Mission):
  • Type: Sample-return mission.
  • Launch: Expected by 2027.
  • Cost: ?2,104 crore.
  • Objective: Sample collection of moon soil and rock to return to Earth.
  • Mission Details: Two LVM-3 launch vehicles will launch components that will dock in Earth orbit before heading to the moon. The samples will be sent back using a bespoke canister.
• Lunar Polar Exploration Mission (LUPEX):
  • Collaboration: Joint mission with Japan.
  • Objective: Exploration of lunar poles with a new lander design, intended for potential crewed missions in future.
• Venus Orbiter Mission:
  • Launch Window: March 2028.
  • Cost: ?1,236 crore.
  • Objective: Study Venus' surface and atmosphere to understand planetary evolution in the Solar System.
• Next Generation Launch Vehicle (NGLV):
  • Development Budget: ?8,240 crore for first three development flights.
  • Objective: A new launcher developed with private sector collaboration for future space missions.

Cabinet Approvals for Space Initiatives

• Human Spaceflight Programme (Gaganyaan):
  • Four new missions under Gaganyaan, including an uncrewed Gaganyaan flight.
  • Focus on developing technologies for India’s first space station, Bharatiya Antariksh Station (BAS), planned by 2028.
• Space-Based Surveillance (SBS) Missions:
  • Phase 3: Approval for building 21 ISRO satellites, with 31 additional satellites by private companies.
  • Total Cost: ?26,968 crore.
• Development of a Third Launch Pad:
  • To support the NGLV and additional space missions at Sriharikota.

Upcoming Satellite Missions

• NISAR (NASA-ISRO Synthetic Aperture Radar):
  • Launch: Early 2025 on a GSAT launch vehicle.
  • Purpose: Earth observation using advanced radar technology.
  • Issue: Protective coating added due to high temperatures during testing.
• Proba-3 (European Space Agency):
  • Launch: November 29, 2024, aboard PSLV-XL.
  • Objective: Study the Sun’s corona using two satellites in formation, mimicking an eclipse to capture unique solar data.

Private Sector Involvement

• Manastu Space & Dhruva Space:
  • Collaboration: Testing green propulsion technology for the LEAP-3 mission.
  • Technology: Hydrogen-peroxide-based green propulsion system.
  • Launch: LEAP-3 mission in 2025.
• Bellatrix Aerospace:
  • Project: Prototype satellite for ultra-low earth orbit at 200 km altitude.
• Ananth Technologies:
  • Achievement: First private company to assemble, integrate, and test Space Docking Experiment (SpaDEx) satellites for ISRO.

Space Science and Research Updates

• Chandrayaan-3:
  • Findings: The crater where Chandrayaan-3 landed is older than the South Pole-Aitken Basin (4.2-4.3 billion years old).
  • Data Source: Optical High-Resolution Camera (Chandrayaan-2) and Pragyaan rover (Chandrayaan-3).
• Astrosat (India’s First Space Observatory):
  • Mission Life: Expected to last two more years (originally planned for 5 years).
  • Significance: Contributed to over 400 published papers based on multi-wavelength space observatory data.

Why is it in the News?

Scientists have brought the Propulsion Module (PM) of the Chandrayaan-3 mission , which initially brought the Vikram lander to within 100 km of the Moon's surface before detaching and executing a historic controlled descent on August 23, back into Earth orbit.

What is a Propulsion Module in Chandrayaan-3?

• The Propulsion Module is a rectangular component of the Chandrayaan-3 spacecraft, equipped with solar panels for power.
• Its primary purpose was to transport the Lander module to the lunar polar circular orbit and facilitate its separation.
• Following separation, the SHAPE payload within the Propulsion Module was activated.
• Initially intended for a three-month operation during the mission, the ISRO announced on December 4th that the Chandrayaan-3's Propulsion Module had been manoeuvred out of lunar orbit.
• Placed high above Earth for an additional mission, the module is currently sustained by residual fuel.
• This bonus mission will showcase technologies crucial for future lunar sample retrieval, according to ISRO.
• As of now, the ISRO has not disclosed its plans for the spacecraft once it depletes its fuel.

Importance of Propulsion Module's Return to Earth's Orbit:

• ISRO highlighted the key achievements resulting from the return manoeuvres conducted on the Propulsion Module (PM) in connection to upcoming missions:
• Planning and executing the trajectory and manoeuvres for the return journey from the Moon to Earth.
• Developing a software module for planning such manoeuvres, along with its initial validation.
• Planning and executing a gravity-assisted flyby around a planet or celestial body.
• Preventing uncontrolled crashing of the PM onto the Moon's surface at the end of its life, aligning with the requirement of avoiding debris creation.

What is Chandrayaan-3 Mission?

Why in the News?

The TransLunar Injection (TLI) was performed successfully from ISRO Telemetry, Tracking and Command Network (ISTRAC) in Bengaluru recently.

What is the TransLunar Injection (TLI)?

• TransLunar Injection (TLI) is a crucial space mission maneuver, propelling spacecraft from Earth's orbit to a trajectory aimed at reaching the Moon.
• An essential step in lunar missions, TLI allows spacecraft to break free from Earth's gravity and commence their journey toward the Moon.
• TLI is executed when the spacecraft reaches the perigee, the closest point to Earth in its orbit.
• During TLI, the spacecraft's propulsion system ignites its engines, accelerating the craft and providing the necessary speed to escape Earth's gravitational pull.
• The thrust and duration of the TLI burn are determined by factors like spacecraft mass, Earth's orbital velocity, and specific mission objectives.
• Following a successful TLI, the spacecraft is directed onto a lunar trajectory, continuing its autonomous journey to the Moon without further reliance on Earth's propulsion.
• Subsequent to TLI, the spacecraft enters a transfer orbit, an elliptical path that intersects with the Moon's orbit.
• The spacecraft traverses this highly eccentric orbit until it reaches the lunar surface.
• As the spacecraft approaches the Moon, additional maneuvers like lunar orbit insertion (LOI) may be executed to enter lunar orbit or facilitate landing, based on the mission's objectives.
• TLI has been effectively utilized in numerous Moon missions, including Apollo, Chang'e, and Artemis missions.