Astronomy & Space Technology

Context: The Union Cabinet approved setting up of Indian Space Research Organisation’s (ISRO) third launch pad at the Satish Dhawan Space Centre (SDSC) in Shriharikota, Andhra Pradesh.

Relevance of the Topic: Prelims: Key facts about India’s Launch Pads. 

ISRO’s Third Launch Pad (TLP)

• The new launch pad will be built at the Satish Dhawan Space Centre (SDSC) in Sriharikota.
• Expenditure involved: Rs. 3985 Crore for the launch pad and the associated facilities.
• Estimated duration of establishment: 48 months or 4 years.
• Utility: 
  • TLP is designed to have universal configuration, such that it can support:
    • NGLV (Next Generation Launch Vehicle) and scaled up configurations of NGLV. 
    • LVM3 vehicles with semicryogenic stages. 
  • It will also act as a standby launch pad for the Second Launch Pad at Sriharikota.
• TLP will be co-located with the second launch pad (SLP), maximising the use of existing infrastructure. 

Key components of TLP

• Jet deflector systems, launch towers, and lightning suppression systems.
• Propellant storage and servicing facilities for liquid methane and cryogenic fuels.
• Advanced range systems, instrumentation, and electronic support facilities.

Significance of TLP

• Launch heavier launch vehicles like NGLV, required for future Indian human spaceflight missions, Bharatiya Antariksh Station (BAS) by 2035 & an Indian Crewed Lunar Landing by 2040 etc.
• Boost Indian Space ecosystem by enabling higher launch frequencies. Meet the growing demand for satellite launches and strengthen India’s position in the global space economy.  

India’s Launch Pads

• Presently, Indian Space Transportation Systems are completely reliant on two launch pads viz. First Launch Pad (FLP) & Second Launch Pad (SLP). 
• First Launch Pad:
  • FLP was realised 30 years ago for PSLV, and continues to provide launch support for Polar Satellite Launch Vehicle (PSLV) & Small Satellite Launch Vehicle (SSLV). 
• Second Launch Pad: 
  • SLP was established primarily for Geosynchronous Satellite Launch Vehicle (GSLV) & Launch Vehicle Mark 3 (LVM3), and also functions as standby for PSLV. 
  • SLP has been operational for almost 20 years and has enhanced the launch capacity towards enabling some commercial missions of PSLV/LVM3, along with the national missions including the Chandrayaan-3 mission. 
  • SLP is getting ready to launch the human rated LVM3 for the Gaganyaan missions.
• Third Launch Pad:
  • TLP is needed to launch NGLV, a new generation of heavier launch vehicles with new propulsion systems, which cannot be met by the existing launch pads.

Context: The Central Government has appointed Dr V Narayanan as the new chairperson of the Indian Space Research Organisation (SRO), and also as the secretary of the Department of Space. He has played a key role in the development of the indigenous cryogenic engine technology. 

Relevance of the Topic:Prelims: Key facts about Polar Satellite Launch Vehicle (PSLV); Geosynchronous Satellite Launch Vehicle (GSLV); Launch Vehicle Mark-3 (LVM3); Small Satellite Launch Vehicle (SSLV); Cryogenic Engine (CE-20). 

About Dr V Narayanan

• He has worked in the Solid Propulsion area of Sounding Rockets and Augmented Satellite Launch Vehicle (ASLV) and Polar Satellite Launch Vehicle (PSLV) at Vikram Sarabhai Space Centre (VSSC).
• He has played a key role in India's development of the cryogenic engine, a technology that was denied to the country by Russia following pressure from the US. 
• Prior to his elevation as the chairman of ISRO, he was serving as the head of the Liquid Propulsion Systems Centre (LPSC) in Kerala since 2018. 
• He is the Chairman of the National Level Human Rated Certification Board (HRCB) for Gaganyaan, India's planned human spaceflight mission.

Satellite Launch Vehicles of ISRO

1. Polar Satellite Launch Vehicle (PSLV): 

• PSLV is an expendable launch vehicle developed and operated by ISRO since its first successful launch in 1994. 
• ​​Workhorse of ISRO known for its reliability, versatility, and cost-effectiveness since 1994.
• Stages: Four-stages launch vehicle
  • First stage is powered by a solid rocket motor (strap-on motors to provide additional thrust to the rocket to overcome air resistance).
  • Second stage uses a liquid propulsion system (Vikas Engine)
  • Third stage is a solid rocket motor 
  • Fourth stage is a liquid-fueled engine 
• PSLV can deliver payloads of up to:
  • 3250 kg to Low Earth Orbit 
  • 1600 kg to Sun Synchronous Orbit 
  • 1400 kg to Geosynchronous Transfer Orbit 
• Successful launches: Chandrayaan-1 Mission (2008), Mars Orbiter Mission/Mangalyaan (2013), 104 satellites at one go (2017). 
• It has been used for launching a wide range of payloads, including Earth observation satellites, navigation satellites, communication satellites, and scientific payloads for various domestic and international customers. 

2. Geosynchronous Satellite Launch Vehicle (GSLV):

• Stages: Three-stage launch vehicle
  • First Stage: Uses four strap-on solid boost motors (HS200).
  • Second Stage: Liquid core stage (L110) powered by two Vikas liquid engines. 
  • Third Stage: Cryogenic Upper Stage with cryogenic engine using liquid Hydrogen and liquid Oxygen for high specific impulse and efficiency.
• GSLV can carry more than 2,200 kg to geostationary orbits, and over 6,000 kg to LEO. Ideal for large communication satellites.
• Issues: GSLV has a patchy track record, has flown 16 times of which 4 are unsuccessful (high failure rate for any rocket). The problems have mainly been with the cryogenic engine used by GSLV that is reverse-engineered on a Russian design. 

3. Launch Vehicle Mark-3 (LVM3):  

• LVM3 (previously referred to as Geosynchronous Satellite Launch Vehicle Mark III, GSLV Mk III) is a three-stage medium-lift launch vehicle developed by ISRO.
• Stages: Three-stage launch vehicle
  • First stage: Solid fuel S200 stage.
  • Second stage: Liquid fuel L110 stage. (Vikas Engine)
  • Third stage: Cryogenic fuel C25 stage (uses 25 tonnes of a mixture of liquid Hydrogen and Liquid oxygen). This upper stage (CE-20 cryogenic engine) is developed entirely in India. 
• Payload capacity (one of the most powerful rockets in ISRO's fleet):
  • 4,000 kilograms to geosynchronous transfer orbit (GTO).
  • 10,000 kilograms to low Earth orbit (LEO). 
• Primarily designed to launch communication satellites into geostationary orbit. 
• Successful launches: Chandrayaan-2, Chandrayaan-3. Human-rated LVM-3 is due to launch crewed missions under Gaganyaan Mission. 

4. Small Satellite Launch Vehicle (SSLV):

• New small satellite launch vehicle developed by ISRO to launch small satellites to Low Earth Orbit (LEO) on ‘launch-on-demand’ basis. 
• Three-stage Launch Vehicle configured with three Solid Propulsion Stages and liquid propulsion based Velocity Trimming Module (VTM) as a terminal stage.
• Can launch Mini, Micro, or Nanosatellites (10 to 500 kg mass) up to 500 km in LEO.
• Capable of multiple orbital drop-offs i.e., launch multiple microsatellites in one launch. 
• SSLVs will cost 1/10th of a PSLV and will need only 72 hours for launch in comparison to 45 days for PSLV. 

ISRO’s Cryogenic Engine (CE-20)

• ISRO has used three cryogenic engines over the years: KVD-1, CE-7.5, and CE-20.
  • KVD-1 was supplied to India in the 1980s by Russia (the Soviet Union).
  • CE-7.5, and CE-20 are India-made, although the design of the CE-7.5 is based on the KVD-1.
  • The GSLV Mk II launch vehicle uses CE-7.5 engines to power the third stage of its ascent.
• CE-20 is an indigenous cryogenic engine ISRO developed to use with the GSLV Mk III (LVM3 launch vehicle). It represents an improvement on the CE-7.5 cryogenic engine.
• Fuel: Liquid hydrogen and liquid oxygen as propellants stored at extremely low temperatures (around -253°C for hydrogen and -183°C for oxygen).
• Advantages:
  • Cryogenic propellants have a high energy density, high fuel efficiency and high specific impulse (more thrust per kilogram of propellant). This allows rockets to carry less fuel, reduces their overall weight and can carry heavier payloads or travel further. 
  • Cryogenic engines are throttleable (ability to vary/adjust their thrust levels during flight). This capability is essential for precise control during ascent, orbit insertion, manoeuvring, and controlled re-entry of a rocket.
• Challenges: 
  • They require complex and expensive infrastructure to store and handle extremely cold propellants. E.g., Hydrogen in liquid form needs to be maintained at -253 degrees C (and the liquid oxygen at -184 degrees C) and leaks very easily.
  • The initial development process of cryogenic engines and maintenance is expensive.
• Note: ISRO accomplished the human rating of its cryogenic engine (CE-20), which will power the cryogenic stage of the human-rated LVM3 launcher for India’s first human space flight mission (Gaganyaan). 

Context: Indian Space Research Organisation’s (ISRO) PSLV-C60 mission is scheduled to be launched on December 30, 2024. 

Relevance of the Topic: Prelims: Space Docking Experiment (SpaDeX); PSLV Orbital Experimental Module

Major Highlights:

• The mission will demonstrate the complex art of satellite docking in space with the Space Docking Experiment (SpaDeX).
  • The PSLV rocket will carry two satellites named Chaser (SDX01) and Target (SDX02). Each weighs 220 kg. 
  • After launch and orbit insertion, the two satellites will attempt to dock at an altitude of 470 kilometers above the Earth.
• The mission will also leverage the PSLV's fourth stage (POEM-4) to host 24 scientific experiments, designed by various ISRO centres, academic institutions, and Indian private companies. 

Read More: SpaDeX: Space Docking Experiment 

Why does SpaDeX matter for India?

• The mission is a strategic step towards several ambitious space objectives, including:
  • Preparing for the Gaganyaan human spaceflight program
  • Enabling Chandrayaan-4 lunar sample return missions
  • Developing the Bharatiya Antariksh Station (BAS), India's proposed space station. 

PSLV Orbital Experimental Module (POEM)

• Developed by: Vikram Sarabhai Space Centre (VSSC).
• POEM is an experimental mission or space platform to perform in-orbit experiments using the final (otherwise discarded) stage of ISRO’s PSLV.
  • PSLV is a four-stage rocket where the first three spent stages fall back into the ocean, and the final stage (PS4) — after launching the satellite into orbit — often ends up as space junk. 
  • In POEM, the spent final stage will be utilised as a stabilised platform to perform experiments. 
• POEM has a dedicated Navigation Guidance and Control (NGC) system to act as the platform’s brain for attitude stabilisation with specified accuracy. 
• POEM will derive its power from solar panels mounted around the PS4 tank, and a Li-Ion battery. It will navigate using four sun sensors, a magnetometer, gyros & NavIC.

POEM-4’s Payloads:

• POEM-4 carries 24 payloads: 14 contributed by various ISRO centres and 10 by academia and private industry. POEM-4 will begin operations after satellite separation. 

Some important payloads include:

• Relocatable Robotic Manipulator-Technology Demonstrator, a.k.a. ‘Walking Robotic Arm,’ developed by ISRO Inertial Systems Unit (IISU), is expected to demonstrate a robotic arm that can move to defined targets on the POEM using an inchworm walking technique.
• Debris Capture Robotic Manipulator to capture tethered space debris with a robotic manipulator. 
• Compact Research module for Orbital Plant Studies to study the germination and growth of eight cowpea seeds in a five- to seven-day experiment in a controlled environment.
• Amity Plant Experimental Module in Space (APEMS) payload. It will compare growth-related changes in plant callus cells using spinach plants in microgravity and earth gravity.
• RVSat-1 payload. It will measure the growth of the gut bacterium (Bacteroides thetaiotaomicron) in space. The experiment is expected to provide data to understand human physiology in space and astronaut health during crewed missions.
• BGS Amateur Radio Payload for Information Transmission (ARPIT). It can transmit audio, text, and images from a satellite to the ground with frequency modulation in the VHF band. It is designed to provide amateur radio satellite services worldwide.
• RUDRA 1.0 HPGP will test a green propulsion system with a thrust of 1 newton and a specific impulse of 220 seconds. 
• VYOM 2U developed by Manastu Space will test a monopropellant as a safer and better performing alternative to hydrazine (the most widely used propellant in the Indian space programme at present). VYOM has a thrust of 1.1 N and a specific impulse greater than 250 seconds.

Context: Black holes are some of the most fascinating objects in space. Recent research has suggested a new way to measure the properties of black holes (mass, spin) by analysing the echoes of light produced when light interacts with Black Holes. 

Relevance of the Topic: Prelims: Black Holes; Terms related to Black Holes; General Theory of Relativity.  

Major Highlights:

• Gravitational lensing: When light passes near a black hole, it bends due to the immense gravitational pull of the black hole. This phenomenon is called gravitational lensing. 
• Creation of light echoes: Gravitational lensing can create light echoes.
  • Light passing around a black hole can take different paths: Some beams of the light may take a direct route to the viewer, while others may pass around the black hole a few times, before getting back on its original path. 
  • This causes the light emitted from a distant object to reach Earth at different intervals. This phenomenon is called a light echo (the beam to arrive second will be an echo of the beam that arrived first).
• Long-baseline interferometry: Scientists theorised that they can use light echoes to measure masses and spins of black holes. The study proposes the use of a technique called long-baseline interferometry (which aims to detect the interference pattern between the light beams arriving at different times) to study characteristics of black holes. 
• Albert Einstein’s general theory of relativity has also predicted the phenomenon of light echoes.

Black Holes

Black holes are the regions of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, has enough energy to escape. The boundary of no escape is called the event horizon. 

• Formation: A black hole forms when a massive star (at least three times the mass of our Sun), exhausts its fuel, explodes in a supernova, and collapses under gravity into an incredibly dense core called a singularity.

Types of Black Holes:

• Stellar Black Holes: 
  • Formed by the collapse of a single massive star at the end of its life cycle. 
  • Mass typically ranges between 3 to 100 times mass of the Sun. 
• Intermediate Black Holes:
  • Formed through merger of stellar black holes or collapse of massive star clusters.
  • Mass between 100 and 1,00,000 times that of the Sun.
• Supermassive Black Holes:
  • Found at the centres of most galaxies, including our Milky Way. Their origin is not exactly understood, but may involve accretion of matter, merger or collapse of massive gas clouds. 
  • Masses range from millions to billions of times the sun’s mass.

Are Black Holes Observable?

• Black holes are not directly observable with telescopes that detect X-rays, light, or other forms of electromagnetic radiation. 
• However, their presence can be inferred through their effects on surrounding matter, and the gravitational waves they produce. E.g.,
  • Emission of X-rays and powerful Gamma rays: If a black hole passes through a cloud of interstellar matter or if a star passes close to a black hole, it will draw matter inward in a process known as accretion. As the attracted matter accelerates and heats up, it emits X-rays and powerful gamma ray bursts that radiate into space. This reflects the presence of black holes.
  • Gravitational waves: Merger of two blackholes produces powerful gravitational waves. The detection of these gravitational waves (Laser Interferometer Gravitational-Wave Observatory, LIGO) can confirm the existence/ location of the black holes. 

Common Terms related to Black Holes: 

1. Supernova: 

• Supernovae are incredibly powerful explosions that occur when a massive supergiant star reaches the end of its life (exhausts its fuel). 
• These explosions release an astonishing amount of energy, up to 10^44 joules.

2. Singularity: 

• The centre of a black hole is a gravitational singularity, a point where the general theory of relativity breaks down, i.e. where its predictions do not apply. 
• A black hole’s great gravitational pull emerges as if from the singularity.

3. Event Horizon (a point of no return): 

• The event horizon is like a boundary around a black hole (around the singularity). Once anything (matter, energy, light) crosses this boundary, it can not escape unless it travels faster than the speed of light (which is impossible). 
• This means nothing, not even light, can escape the black hole's strong gravity because the speed needed to escape at the event horizon should be greater than the speed of light.

4. Ergosphere: 

• The Ergosphere is a bigger sphere, outside the event horizon of a black hole, where matter can enter and then return (escape the black hole's gravitational pull), if they are moving with speeds very close to the speed of light.
• Rotating (Kerr) black holes have an ergosphere. In the Ergosphere, spacetime is dragged along with the rotation of the black hole. 
• Ergosphere derives its name from the fact that energy can be extracted from the black hole via the Penrose process.
  • Researchers have proposed the concept of directing objects into the ergosphere of a black hole, allowing it to accelerate there along the black hole’s direction of rotation, resulting in an increased velocity upon exiting. 

5. Accretion Disc: 

• An accretion disc is a flat, rotating structure of matter (such as gas, dust, or other material) that forms around a black hole. 
• The material in the accretion disc spirals inward due to gravitational attraction of the black hole. 
• As it spirals inward, the material often heats up due to friction and gravitational forces, emitting various forms of electromagnetic radiation, including visible light, X-rays, gamma rays and radio waves. 

6. Spaghettification: 

• Spaghettification refers to the effect of extreme gravitational pressure on any particle or body of matter, in particular, when exposed to the extreme forces of the black hole. 
• When a particle draws too close to the event horizon, it is stretched into long thin shapes. E.g., If an astronaut falls into the event horizon, as the gravity is inversely proportional to distance, the pull on the falling astronaut’s legs will be substantially greater than the pull on his or her upper torso. Subsequently, stretching him like spaghetti (pasta). 

Context: India’s Space Journey which began modesty six decades ago has now transitioned into an era of global collaboration and private-sector participation. It is a testimony to the country’s expanding space ecosystem. 

The Historical Context: 

• November 1963: Indian scientists launched a Nike-Apache sounding rocket from Thumba, Kerala. These rockets helped the Indian Space Research Organisation (ISRO) master solid propellant technology,  a foundation for India's launch vehicle capabilities.

Evolution to Global Participation:

Fast forward to 2024, India not only launches satellites for domestic needs but also collaborates internationally. 

• GSAT-N2 satellite launch:
  • Recently, India launched GSAT-N2 satellite aboard a SpaceX Falcon 9 rocket from Florida, the US.
  • The satellite, weighing 4700 kg, exceeded the payload capacity of India’s most powerful rocket, the Launch Vehicle Mark 3 (LVM-3), necessitating its launch aboard a SpaceX Falcon 9.
  • It is a Ka-band high-throughput satellite to enhance broadband services in underserved areas, including the northeast, Andaman & Nicobar Islands, and Lakshadweep. It will also support services like in-flight internet connectivity and the Smart Cities Mission.
  • The satellite is built by ISRO and will be placed in the geostationary orbit.  
• Upcoming PSLV-C59 Mission: PSLV-C59 mission scheduled for December 4, 2024. It will carry the European Proba-3 spacecraft to study the Sun, using extended length configuration of ISRO’s trusted Polar Satellite Launch Vehicle (PSLV-XL).
• Indian Astronauts in Training: India’s astronaut-designate Shubhanshu Shukla, who is set to fly to the International Space Station in 2025, is undergoing training at the European Space Agency’s European Astronaut Centre.
• India Joins SKAO: In 2024, India became a full member of the Square Kilometre Array Observatory (SKAO). SKAO is an international effort to build the world’s most advanced radio telescope in Australia and South Africa. India will contribute financially as well as in advanced electronics and engineering for telescope components in exchange for scientific data collected by the telescope.

Recent Scientific Advancements:

• India’s first Space Analog Mission: 
  • Indian Space Research Organisation (ISRO) has announced the launch of its first analog space mission at Leh in Ladakh, simulating lunar and Martian conditions. 
  • This setup will help study the challenges astronauts will face in a base station beyond Earth and gather critical data that will support India’s Gaganyaan program and future missions.
• Biological Experiments on Bharatiya Antariksh Station: The Departments of Space and of Biotechnology have signed agreements to conduct biological experiments aboard India’s forthcoming Bharatiya Antariksh Station, marking a leap in interdisciplinary research.
• Breakthroughs from Aditya-L1: A team led by researchers at the Indian Institute of Astrophysics, Bengaluru, used data from Visible Emission Line Coronagraph (VELC) instrument onboard Aditya-L1 to accurately predict the time of a coronal mass ejection, demonstrating India's capability in space weather research.

Private Sector Participation:

• Pixxel’s Fireflies (India-American firm): A set of six hyperspectral satellites are expected to be launched early next year. Each satellite weighs around 50 kg, has a native 5 m spatial resolution, and scans 40-km swaths for data in more than 150 spectral bands. These satellites constitute the first batch in a proposed constellation of 24 satellites. These satellites will provide data that can help detect crop diseases, water-stressed areas, real-time deforestation, and ocean pollution early.
• GalaxEye Space’s Tech Demo: A payload on board the PSLV’s Orbital Experimental Module (POEM) platform. The Tech Demo will test subsystems of a synthetic aperture radar (SAR).
• PierSight Space’s Varuna Mission: A payload on PSLV POEM called ‘Varuna’, which will demonstrate a deployable reflectarray antenna and test SAR and aeronautical information service avionics in orbit.
• HEX20’s Nila Satellite: A 5-kg cubesat satellite to be launched on SpaceX’s Transporter 13 mission in February 2025. The cubesat will host different payloads and provide data-processing services. A ground station will be built in Thiruvananthapuram, Kerala, to control and receive data from the satellite.
• SatSure: SatSure is working with the Ministry of Electronics and Information Technology (MEiTY) to map rural property across over two lakh villages. ‘Svamvita’ programme will capture images of 3-5 cm resolution and SatSure will use its machine-learning tools developed for satellite data to extract and classify the relevant features (building footprints, roof type, roads, and water bodies).