Context: Chandrayaan-3's ChaSTE provided crucial temperature data from the Moon's high-latitude regions, enhancing the understanding of potential water-ice deposits.
Relevance of the Topic: Prelims: Key facts about Chandrayaan Mission 3; Chandra’s Surface Thermophysical Experiment (ChaSTE).
ChaSTE is an instrument aboard the Vikram lander to measure temperaturesin situ near the moon’s south pole.
ChaSTE became the first mission to successfully penetrate the soil of a celestial body to deploy a thermal probe for in-situ measurement of the surface temperature.
The ChaSTE probe features 10 temperature sensors spaced about 1 cm apart along its length.
The probe was pushed into the lunar soil using a rotation-based deployment mechanism.
ChaSTE tunnelled into the soil to a final depth of 10 cm, then collected the measurements throughout the Chandrayaan-3 mission lifespan (1 lunar day).
Observations:
In-situ temperature measurement: The peak surface temperature at Shiv Shakti landing site was measured to be 355 K (82°C) — 25 K higher than the expected 330 K, predicted by earlier observations.
The observations indicate that the lunar surface temperatures show a significant spatial variability at high latitudes, unlike at the equatorial regions.
Scientists used the data from ChaSTE to report that water ice is more prevalent on the moon than expected. Water-ice prospecting is a crucial step in unlocking the Moon’s potential for supporting human habitat and furthering exploration.
Context: Recently, astronomers have located 128 new moons orbiting Saturn using the Canada France Hawaii telescope. Saturn now officially has 274 confirmed moons, the highest for any planet in the Solar System. Saturn is followed by Jupiter with 95 known moons.
Relevance of the Topic:Prelims: Key facts about Saturn; Saturn’s Moons.
Key facts about Saturn
Saturn is the sixth planet from the Sun. It is the second-largest planet in our Solar System, after Jupiter.
Saturn is a gas giant dominated by hydrogen and helium. Its atmosphere contains hydrogen, helium, methane, ammonia, and other gases, giving it a yellowish-brown appearance. The planet is thought to have a rocky core.
Saturn's average density is 0.69 g/cm³, making it the only planet less dense than water by about 30%. Its low density is due to its vast gaseous atmosphere.
Saturn's rapid rotation gives it an oblate shape. It is flattened at the poles and bulging at the equator. Saturn's rings are made of ice, dust, and rock.
Saturn orbits the Sun at an average distance of 9.59 astronomical units (AU), or roughly 1,434 million kilometers. The orbital period is about 29.45 Earth years.
Saturn is known for its large and intense storm systems, such as the Great White Spot. This massive storm occurs roughly once every Saturnian year (about 29 Earth years). These storms can last for months and cover vast areas.
Saturn’s Important Moons
Saturn has 274 moons recognised by the International Astronomical Union.
Titan:
Titan is Saturn's largest moon and is one of the most Earth-like bodies in the Solar System. Titan is larger (though less massive) than Mercury.
It is the only moon in the Solar System with a dense atmosphere.
Nitrogen and methane extend around the moon 10 times as far into space as Earth's atmosphere, sometimes falling to Titan's surface as methane rain.
It has liquid hydrocarbon lakes in the polar region. Cassini-Huygens spacecraft landed on Titan in 2005.
Enceladus:
Enceladus is an icy Saturnian moon that has a liquid ocean of water beneath its crust, making it one of the most promising places to look for signs of life beyond Earth.
It has the whitest, most reflective surface in the solar system.
The strange moon spews its ocean out into space. In 2005, NASA's Cassini spacecraft found icy water particles gushing from the surface at approximately 400 meters per second.
Nanograins of silica have been found in Saturn's E-ring, which suggests the presence of hydrothermal vents within Enceladus' ocean.
Context: Physicists from the US have successfully demonstrated a new way to detect radioactive materials from a distance using carbon-dioxide lasers.
Relevance of the Topic: Prelims: Basics of the technology and potential applications.
Avalanche-Based Laser for Radiation Detection
The researchers used a carbon-dioxide laser to detect the alpha particles from a radioactive source (Caesium-137) located 10 m away.
Mechanism:
Radioactive decay: When radioactive material undergoes radioactive decay it releases charged particles (alpha, beta & gamma radiation). These charged particles ionise the air around it, i.e. separate its positive and negative charges, and create a state of matter called plasma.
Avalanche breakdown: The negative charges (or electrons) can be accelerated to collide with other atoms of air, and release even more electrons. This is avalanche breakdown.
Laser-based detection: The researchers used a carbon-dioxide laser emitting long wave infrared radiation to accelerate the electrons, and making them emit light (optical backscatter). The sensors placed near the laser were able to detect the alpha particles from the radioactive source.
Advantages of the Laser-based detection Technique
Detecting low concentration radioactive source: The ability of lasers to induce (initiate) electron avalanches can be utilised to detect even very low concentration of ionisation. The lasers can be scaled to detect gamma rays that travel much farther in air than alpha particles, and have low density of ionisation.
Scalability: The researchers are scaling up the current detection capabilities to detect radiation from distances over 100 metres.
Potential Applications
National security: Detection of illicit possession or smuggling of radioactive substances, especially at airports or borders.
Nuclear safety: Detection of radiation leakage from Nuclear reactors and installations.
Environmental monitoring: Tracking radioactive contamination in air, water, soil, mines, space etc.
Exploration of naturally occurring radioactive materials.
Context: Recently, researchers from China have transplanted a gene-modified liver from a miniature piginto a human recipient diagnosed with brain death. The transplantation was carried out to evaluate the performance of the transplanted organ over a 10-day observation period.
Relevance of the Topic: Prelims: Key facts about Xenotransplantation.
What is Xenotransplantation?
Xenotransplantation is any procedure that involves the transplantation, implantation or infusion into a human recipient:
live cells, tissues, or organs from a non-human animal source.
human body fluids, cells, tissues or organs that have had ex vivo contact with live non-human animal cells, tissues or organs. Essentially, it is the use of animal cells and organs to heal humans.
Need: To bridge the need for a limited supply of organs and cells for clinical transplantation, and address the shortage of organs from human donors.
Source:Pigs are the most commonly considered animals due to their size compatibility and organ similarities with humans.
Natural lifespan of a pig is 30 years, they are easily bred and can have organs of similar size to humans.
Gene editing in organs from pigs can reduce immune rejection, and can make organ transplants to humans possible.
Limitations
Successful xenotransplantation faces challenges such as organ rejection, risk of cross-species infections and social acceptance.
In 2022, the first xenotransplantation of a genetically-modified pig heart was done. However, the patient passed away after two months.
In 2024, the first recipient of a modified pig kidney transplant passed away, around two months after the surgery was carried out.
The latest development
Six genes had been edited in the transplanted liver. The gene edits included removal of genes that mediate rejection and the insertion of human transgenes to facilitate compatibility. The liver produced bile and albumin, maintained stable blood flow and showed no signs of rejection.
These findings suggest that gene-modified pig livers can survive and function in human bodies. This can pave the way for using gene-edited organs for xenotransplantation.
However, the study was limited to a 10-day observation period, and only basic liver functions were measured. Further research is needed to evaluate long-term outcomes.
Context: A recent research paper has pitched two efficient ways of producingHydrogenfrom biomass, through — Rapid pyrolysis and Microwave-assisted pyrolysis.
Relevance of the Topic: Prelims: Key facts about Hydrogen production through Pyrolysis.
Biomass Pyrolysis and Hydrogen Production
Pyrolysis is a thermochemical process of degradation of biomass by heat in the absence of oxygen. This results in the production of bio-charcoal, bio-oil, and syn gas (rich in Hydrogen).
Agricultural waste is heated at high temperature without burning it.
This heating breaks down the biomass into different products.
Pyrolysis can help:
Produce Hydrogen and help India meet its renewable energy goal.
Produce biomass charcoal, which helps capture carbon and improves soil health.
Utilise large amounts of biomass available in the country (burning of which otherwise produces greenhouse gases).
Advanced Pyrolytic Methods:
1. Rapid Pyrolysis:
Rapid pyrolysis requires 400–600 degree C temperature and heating rate of 10–100 degree C per minute.
Rapid pyrolysis processes the raw material in merely 0.5–2 seconds, compared with at least 30 minutes in conventional pyrolysis, and is more efficient.
The yield from fast pyrolysis includes 35–50% bio-oil, 20–30% biochar, and 15–25% syngas.
2. Microwave Pyrolysis:
Microwave pyrolysis uses electromagnetic waves to instantly heat biomass. It is usually carried out in a low-oxygen or oxygen-free environment at 500-700 degree C.
The primary goal is to improve energy transfer and hydrogen production rate using biomass. It provides fine heating control and focused energy absorption, thereby making it more efficient.
In microwave pyrolysis, heat transfer occurs directly within the feedstock through convection rather than conduction, eliminating the need for external drying of biomass.
Challenges:
Ensuring regular supply of biomass feedstock from agriculture and forestry. Proper controls and different feedstocks are needed to reduce product variation.
Tailoring Reactor design, operating conditions, and catalysts to suit Indian biomass resources to optimise hydrogen production.
Inadequate infrastructure (poor road networks and transportation systems) can limit supply-chains and thus increase project cost.
Uranium Enrichment is the process of increasing the concentration of Uranium-235 (U-235) in natural Uranium, in order to use the isotope for production of nuclear power and nuclear weapons.
Relevance of the Topic:Prelims: Key facts about Uranium Enrichment; Uses of Enriched Uranium.
Need for Uranium Enrichment
Natural Uranium consists of three major isotopes:
Uranium-238 (99.284% natural abundance)
Uranium-235 (0.711%)
Uranium-234 (0.005%)
U-235 is the only nuclide existing in nature (in appreciable amount) that is fissile with thermal neutrons. The production of nuclear energy in atomic reactors is from the ‘fission’ or splitting of the U-235 atoms.
Since the natural Uranium does not have a high enough concentration of U-235, Uranium enrichment is needed to create an effective nuclear fuel. In Enriched Uranium, the percent composition of U- 235 is increased through the process of isotope separation.
Uranium Enrichment Process
The enrichment centrifuge is a device used to extract U-235 isotope from a sample of natural Uranium.
Conversion to gas: Natural Uranium is converted into a gas (Uranium hexafluoride, UF6) and flowed into the centrifuge.
Centrifuge separation: The centrifuge spins the gas at extremely high speeds (~50,000 revolutions per minute). U-238 is slightly more dense than U-235, so it moves outwards. U-235 (lighter) collects towards the centre.
Multiple stages of Enrichment: The process of repeated through multiple centrifuges to further separate U-238 out. Over multiple stages, the sample becomes more enriched in U-235.
Material used in centrifuge: The spinning component is made of strong lightweight material (like carbon fibre) that does not disintegrate during such extreme motion.
Uses of Enriched Uranium
Enriched Uranium is a critical component for both civil nuclear power generation and military nuclear weapons.
Nuclear power reactors need the Uranium fuel to contain 3-5% U-235, depending on the reactor design.
Nuclear weapons need U-235 to be enriched to around 90%.
What is Centrifugal Force?
Centrifugal force is an outward force that is experienced by an object moving in a circular path. It is directed away from the center of the circle of rotation.
Centrifugal force is directly proportional to the mass of an object. That is the reason why U-238 (heavier) experiences a stronger outwards force than U-235 (lighter). This allows the separation between the two isotopes (U-238 & U-235).
Context: In March 2025,NASA's Parker Solar Probe performed its latest flyby, passing within 8 million miles (6.1 million kilometers) of the surface of the sun. Flying at a record-breaking speed of 692,000 kilometers per hour, it shattered its own previous record made in December last year.
Relevance of the topic: Prelims: Key facts about the Parker Solar Probe.
Major Highlights:
On 24 December 2024, the Parker Solar probe made its closest approach to the Sun, coming to a distance of 6.1 million km (0.04 AU) from the surface.
Its beacon signal was received on 26 December, showing that it had survived the passage through the corona (survived the heat).
The spacecraft has become the closest ever artificial object to the Sun.
Significance: The flyby is a major step forward in understanding the Sun and its impact on our solar system.
About Parker Solar Probe
The Parker Solar Probe was launched in 2018 to make observations of the Sun's outer corona.
Mission of: National Aeronautics and Space Administration (NASA).
Aim:
Trace the flow of energy that heats the solar corona and accelerates the solar wind.
Determine the structure and dynamics of the plasma and magnetic fields.
Explore mechanisms that accelerate and transport energetic particles.
The spacecraft has become the closest ever artificial object to the Sun. It has circled gradually closer to the sun, flying past Venus in order to use the planet’s gravity to move it into a tighter orbit.
The spacecraft's systems are protected from the extreme heat and radiation near the Sun by a solar shield.
The solar shield is mounted on the Sun-facing side of the spacecraft.
It is made from reinforced carbon–carbon composite with a carbon foam core.
It is designed to withstand temperatures outside the spacecraft of over 1370 °C.
The mission represents a huge step forward in our understanding of the Sun. Scientists are hopeful that the information it provides will help us learn not only about our star but also about how other stars in the universe work.
Context: Recently, the Defence Research and Development Organisation (DRDO) successfully tested the indigenously-developed Vertically Launched Short-Range Surface-to-Air Missile (VLSRSAM), in collaboration with the Indian Navy at the Integrated Test Range (ITR) Chandipur, Odisha.
Relevance of the Topic:Prelims: Key facts about VLSRSAM (Vertically Launched Short-Range Surface-to-Air Missile).
About VLSRSAM
VLSRSAM (Vertically Launched Short-Range Surface-to-Air Missile) is a ship-borne surface-to-air missile.
Designed To: Neutralise airborne threats including- aircraft, helicopters, drones, and other incoming missiles, particularly at short ranges.
Key details of VLSRSAM:
Launch Mode: Fired from a land-based vertical launcher.
Weight: ~170 kg, and is powered by a solid propellant.
Maximum speed: Mach 4.5
Maximum altitude: 16 km,and has a range sufficient to engage high-speed targets.
Guidance System:
Mid-course phase: Uses a fibre-optic gyroscope-based inertial guidance system, ensuring stable flight towards the target.
Terminal phase: Switches to active radar homing for precise target acquisition and guidance. Can engage targets with high accuracy even at low altitudes.
Recent Successful flight-Test
Near-Boundary-Low Altitude Capability: Demonstrated the missile’s ability to operate effectively at low altitudes.
Technological aspects: The missile successfully destroyed the target, exhibiting:
High turn rate for engaging close-range threats.
Pin-point accuracy and reliability in operation.
Key components tested: Indigenous Radio Frequency (RF) Seeker; Multi-Function Radar; Weapon Control System. All elements performed as expected in combat configuration.
Significance:
Tested for reliability and accuracy. Demonstrates agility and precision in targeting, making it highly effective against fast-moving, low-flying aerial threats.
Force multiplier for the Indian Navy, significantly enhancing its air defence capabilities, particularly in protecting high-value assets in the maritime domain.
Enhances India's self-reliance in defence technology.
Context: Public Accounts Committee has raised concerns over the underutilisation of six transponders in GSAT-18. It has recommended that the Department of Space be more economically prudent while planning future space projects.
Relevance of the Topic: Prelims: GSAT-18; Communication satellites.
About GSAT-18:
GSAT-18 is a communication satellite launched by Indian Space Research Organisation (ISRO) in 2016.
Launched using: Heavy-duty Ariane-5 rocket from Kourou, French Guiana.
Weight: 3404 kg (Ariane-5 was used because GSLV Mk-III was not operational, at that time)
Mission Life: 15 years (until 2032)
Location: Geostationary Orbit
Transponders: 48 communication transponders (Extended C-band, Normal C-band, and Ku-band)
Services provided: DTH broadcasting, Telecommunications, VSAT, broadband internet services.
It strengthens ISRO’s operational fleet of 14 telecommunication satellites, and ensures continuity of communication services by replacing ageing satellites.
Highlights of the PAC report
Economic viability concern: Presently, six transponders in GSAT are kept idle till the year 2027 (would be utilised from 2027-2032). The non-ulilisation of six transponders for 11 years (since 2016) raises concerns about the cost-effectiveness of the mission.
Loss of revenue: This non-utilisation has led to a financial loss of ₹117 crore.
The Department of Space has clarified that the GSAT-18’s extra transponders acted as a backup in case of any failure in transponders, to provide continuity in services.
Context: The Ministry of Defence has signed contracts with Armoured Vehicle Nigam Limited for the acquisition of the Nag Missile System (NAMIS) Tracked version of the anti-tank weapon platform.
Relevance of the Topic: Prelims: NAMIS (Tr) anti-tank weapon platform.
NAMIS (Tracked)
NAMIS (Tracked) is a sophisticated anti-tank weapon system, which serves as a mobile platform to launch Nag anti-tank guided missiles.
Purpose: To greatly enhance the Mechanised Infantry's strength and enhance Indian Army’s operational readiness across a varied spectrum of operations.
Developed by: Defence Research and Development Laboratory (DRDO).
Key Features of NAMIS (Tr):
Armed with Nag ATGM: It is equipped with Nag missile, an all-weather, fire-and-forget, lock-on after launch, anti-tank guided missile (ATGM). It can deploy multiple Nag missiles in succession.
Thermal Imaging: It is equipped with an advanced sighting system to engage targets even in low visibility conditions and for enhanced firepower and lethality.
Significance: The system is part of India's push for self-reliance in defense manufacturing, aligning with the Atma Nirbhar Bharat initiative, which aims to bolster indigenous capabilities in military technology.
Context: The European Space Agency (ESA) has shut down its Gaia Space Observatory in March 2025. Gaia used its thrusters for the final time to slowly drift into its “retirement orbit” around the Sun.
Relevance of the Topic: Prelims: Key facts about Gaia Space Observatory.
About Gaia Space Observatory
GAIA (Global Astrometric Interferometer for Astrophysics) is a space astrometry mission of ESA.
Launched: 2013
Location: Lagrange point 2 (around 1.5 million kilometres ‘behind’ the Earth, when viewed from the Sun)
Aim: To create the most precise, three-dimensional map of the Milky Way galaxy.
Gaia has tracked over 2 billion stars and space objects. The spacecraft is fitted with three instruments – an astrometer, a photometer and a spectrometer – that help interpret the location and motion of stars and other objects.
Lagrange points are positions in a moving two-body system where the combined gravitational forces of two large bodies (such as the Sun and Earth or Earth and the Moon) acting on a third body of smaller mass cancel each other out.
While absolute neutralisation is not achievable due to the influence of other celestial bodies (such as Moon, Mars, and Venus etc.), they provide a stable position where a spacecraft may be "parked" to make observations.
There are five Lagrange points located along the line connecting the two larger celestial bodies.
L1 point: Located roughly 1.5 million kilometres from Earth. It provides an uninterrupted view of the Sun (the satellite can view the Sun without eclipses).
L2 point: Provides an unobstructed view of the Universe and is stable enough for long-duration observations. Location for space-based observatories (James Webb Space Telescope).
L3 point: Lies behind the Sun, opposite to Earth. Offers the potential to observe the far side of the Sun. Possible location for a future space-based observatory.
L4 and L5 point: Stable locations but are relatively farther from Earth than L1.
Achievements of GAIA
Data allowed recreation of a precise 3D map of the Milky Way galaxy; Help understand the shape of our galaxy.
Uncovered a new kind of black hole – including one close to the Earth. Black holes were previously discovered by light emitted by materials falling in, but those discovered by Gaia can only be detected by their gravitational effects.
Detected over 1,50,000 asteroids and projected their orbits, including those that may pose a threat to the Earth in the future.
Context: A recent study carried out by the US researchers has found that toxic dust on Mars would make a future mission to the red planet extremely hazardous for astronauts.
Relevance of the Topic:Prelims: Key facts about Mars; Mars Missions.
Major Highlights of the Report
Fine dust: The size of a Martian dust particle is quite small (it is about 4% the width of a human hair). The fine particles of the dust could penetrate deep into the lungs and enter the bloodstream and cause respiratory issues.
Toxic elements in Martian dust: Silica, gypsum, perchlorates, chromium, arsenic and nanophase iron oxides. The impact of these toxins could be more significant due to microgravity and radiation on Mars.
Dust storms: Every Martian year (which lasts ~687 Earth days), the planet witnesses regional dust storms. Every three Martian years, these storms grow into planet-encircling dust storms.
The use of air filters, self-cleaning space suits and electrostatic repulsion devices (remove dust particles) can limit exposure to dust.
Facts about Mars
Fourth planet from the Sun and second-smallest planet in the Solar System. Mars is about half the size of Earth.
Similarity to Earth (Orbit and Rotation):
Mars rotates every 24.6 hours, which is very similar to one day on Earth (23.9 hours).
Mars' axis of rotation is tilted 25 degrees with respect to the plane of its orbit around the Sun. Earth’s axial tilt is 23.4 degrees.
Like Earth, Mars has distinct seasons, but they last longer than seasons on Earth since Mars takes longer to orbit the Sun.
Red Planet: Mars looks reddish due to oxidation or rusting of iron in rocks, and dust of Mars.
Mars has a thin atmosphere made up mostly of carbon dioxide, nitrogen and argon gases.
Mars has no magnetic field, but certain areas of Martian crust in the southern hemisphere are highly magnetised, indicating traces of a magnetic field.
Mars has two small moons, Phobos and Deimos, that may be captured asteroids.
Mars has the largest volcano in the solar system i.e., Olympus Mons. It is 3 times taller than Earth's Mt. Everest.
Martian Missions:
The Soviet Union in 1971 became the first country to carry out a Mars landing, Mars-3. The second country to reach Mars’s surface is the USA.
India’s Mars Orbiter Mission (Mangalyaan) was launched from Satish Dhawan Space Centre in Andhra Pradesh by ISRO in 2013.
Reasons for fascination with Mars:
Mars has several Earth-like features– such as clouds, polar ice caps, volcanoes, and seasonal weather patterns.
Life may have evolved on Mars in the past. Conditions on early Mars were very similar to that of Earth. It was once warm enough to allow water to flow through it. It had a thick atmosphere, which enabled stability of water on the surface of Mars.
Mars is the only planet that humans can visit or inhabit in the long term. Mars is comparatively hospitable in terms of temperature, with an approximate range between 20 degrees Celsius at Equator to minus 125 degrees C at poles.
However, no human has set foot on Mars because the atmosphere on Mars is very thin, consisting of mostly carbon dioxide with no breathable oxygen, making it difficult for astronauts to survive there.
