Science and Technology: December 2023 UPSC Current Affairs | Science & Technology for UPSC CSE PDF Download

Web Browsers

Context: Web browsers serve as our digital gateways to the expansive realm of the internet, simplifying our ability to navigate and reach web pages effortlessly through a simple click.

What are Web Browsers?

• Web browsers are application software designed for navigating the World Wide Web (www), serving as an interface between users and web servers. They send requests to servers for web documents and services, interpreting HTML (Hypertext Markup Language) to display webpages.
• When browsing, the browser loads web pages composed of HTML, incorporating text, links, images, stylesheets, and JavaScript functions. Examples of web browsers include Google Chrome, Microsoft Edge, Mozilla Firefox, and Safari.
• The origins of web browsing trace back to Tim Berners-Lee's introduction of the World Wide Web in 1990, alongside the first web browser, 'WorldWideWeb.' The revolutionary Mosaic browser in 1993 introduced images to web pages, transforming user interaction. Subsequent browsers like Netscape Navigator and Internet Explorer brought innovations such as bookmarks and user-friendly features, sparking competitive 'Browser Wars.'
• Mozilla Firefox in 2004-2005 revolutionized browsing with tabbed browsing and add-ons, challenging Internet Explorer's dominance. Google's Chrome emerged in 2008 with speed and simplicity, reshaping the browser market. Other browsers like Apple's Safari and Microsoft Edge evolved, offering diverse user-oriented options.
• Web browsers function by initiating website visits through digital communication, receiving HTML, CSS (Cascading Style Sheets), and JavaScript files. HTML outlines webpage structure, CSS adds style and aesthetics, while JavaScript enables interactivity. Browsers render web pages by interpreting these elements, manage browsing data via cookies and cache, and implement security measures like encryption protocols (HTTPS) to protect users from potential threats.

What is the Future of Browsing?

• As technology hurtles forward, web browsers evolve in tandem. They are embracing cutting-edge technologies like WebAssembly, a format that enables near-native performance within the browser environment.
• Support for Virtual Reality (VR) and Augmented Reality (AR) experiences is also on the horizon, promising immersive online interactions.
• Additionally, privacy features are being bolstered, providing users with greater control over their digital footprint.
• Web browsers are the unsung heroes of our digital endeavours, translating code into the dynamic web pages that form the backbone of our online experiences.
• By unravelling the intricate tapestry of processes that underlie their operation, we gain a newfound appreciation for the seamless magic they conjure with every click.

Chandrayaan-3 Propulsion Module Returns to Earth’s Orbit

Context: In recent news, scientists accomplished the retrieval of the Propulsion Module (PM) from the Chandrayaan-3 mission, responsible for transporting the Vikram lander within 100 km of the Moon's surface before detachment.

• This significant achievement involved a controlled descent to the lunar surface followed by a successful return to Earth's orbit.

What is the Chandrayaan Mission?

India has initiated three Chandrayaan Missions - Chandrayaan-1, Chandrayaan-2, and Chandrayaan-3.

Chandrayaan-1:

• Chandrayaan-1 marked India's inaugural mission to the Moon, successfully launched in 2008. Its primary objective was to orbit the Moon and conduct observations using its onboard instruments.

Key Discoveries of Chandrayaan-1:

• Confirmed the existence of water on the lunar surface.
• Uncovered evidence of lunar caves formed by ancient lava flows.
• Identified indications of past tectonic activity on the Moon's surface.
• Discovered faults and fractures that could potentially be attributed to prior internal tectonic events combined with meteorite impacts.

Chandrayaan-2:

• Chandrayaan-2 comprised an integrated spacecraft comprising three components: an orbiter circling the Moon, Vikram (named after Vikram Sarabhai) the lander, and Pragyan (meaning wisdom) the rover. Each was equipped with scientific instruments for lunar studies.

Launch Date: July 22, 2019

• Lander Vikram: Intended for stationary study of the moon’s atmosphere and seismic activity upon landing.
• Rover Pragyan: A solar-powered, six-wheeled vehicle designed for surface exploration, observations, and data collection.
• Chandrayaan-2's lander encountered a hard landing or crash on the lunar surface due to high velocity. Nevertheless, the orbiter remains operational and will establish communication with Chandrayaan-3's lander.

Chandrayaan-3:

• India's third lunar mission, Chandrayaan-3, was the second endeavor to achieve a soft landing on the moon's surface.
• Launch Date: July 14, 2023

Objectives:

• Demonstration of Safe and Soft Landing on the Lunar Surface
• Testing Rover mobility on the moon's surface
• Conducting in-situ scientific experiments
• It comprises an indigenous Lander Module (LM), Propulsion Module (PM), and Rover. The mission aims to develop and demonstrate new technologies required for interplanetary missions.

What is the Chandrayaan-3 Propulsion Module?

• Chandrayaan-3: It utilized a lightweight Propulsion Module for the lander's journey to the Moon instead of a complete orbiter.
• SpectroPolarimetry of Habitable Planet Earth (SHAPE): The Chandrayaan-3 propulsion module carried a single instrument called SHAPE.
  • It was an experimental payload designed to study Earth's characteristics that make it habitable, aiming to identify habitable exoplanets.
• Pragyaan Rover: The propulsion module separated from the lander, which carried the Pragyaan rover. It was anticipated to orbit the Moon for an additional six months, with SHAPE observing Earth.

How Does the Propulsion Module Return to Earth Orbit?

• The experiment allows ISRO to work towards developing a software module to plan going forward.
• Taking fuel availability and safety into account, designed the best trajectory for the Earth return.
• The SHAPE payload is operated whenever Earth is visible, including a special operation.

Six Exoplanets Found Orbiting Around HD 110067

Context: A recent discovery has identified six exoplanets orbiting a bright star (HD 110067) situated in the Coma Berenices constellation nearby.

About HD110067

• HD 110067 is a star known to host six sub-Neptune exoplanets. Positioned in the Coma Berenices constellation, near Virgo in the northern sky, this star is located approximately 100 light-years away from Earth.
• The six planets orbiting HD 110067 follow a distinct pattern. They form a "resonant chain" characterized by successive pairs of planets in ratios of 3:2, 3:2, 3:2, 4:3, and 4:3.
• NASA's Transiting Exoplanet Survey Satellite (TESS) observed a decrease in the star's brightness in 2020, indicating the passage of planets in front of the star.

What are Exoplanets?

• Exoplanets are celestial bodies that orbit stars outside our solar system. Initially confirmed in 1992, over 5,000 exoplanets have been identified to date. Scientists speculate that planets might outnumber stars in the universe, with each star potentially hosting at least one planet. 
• These exoplanets exhibit diverse characteristics, ranging from gas giants larger than Jupiter to rocky planets as small as Earth, and can possess a wide range of temperatures, from extremely hot to extremely cold.

Discovery:

• Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit.
• So, astronomers use other ways to detect and study exoplanets such as looking at the effects these planets have on the stars they orbit.
• Scientists rely on indirect methods, such as the transit method, which is measuring the dimming of a star that happens to have a planet pass in front of it.
• Other detection methods include gravitational microlensing– Light from a distant star is bent and focused by gravity as a planet passes between the star and Earth. The same method could hypothetically use our Sun to see exoplanets.

Significance:

• Studying exoplanets not only broadens our understanding of other solar systems but also helps us piece together information about our own planetary system and origin.
• However, the most compelling reason to learn about them is to find the answer to one of the most profound and thought-provoking questions of humankind — are we alone in this universe?
• Another important element of the study is finding out the distance between an exoplanet and its host star.
• This helps scientists determine if a discovered world is habitable or not. If an exoplanet is too close to the star, it might be too hot to sustain liquid water. If it’s too far, it might only have frozen water.
• When a planet is at a distance that enables it to have liquid water, it is said to be in the “Goldilocks zone” or the habitable zone.

A massive exoplanet closely orbits a very low-mass star

• The detection of a Neptune-mass exoplanet orbiting the ultra-low-mass M dwarf star LHS 3154 presents a challenge to existing theories of planet formation. This planet, with a mass approximately 13 times that of Earth, orbits closely around a star that is nine times less massive than the Sun. 
• This discovery suggests that smaller stars may have the capacity to host larger planets, challenging previous assumptions. While several substantial planet candidates have been identified around a limited number of very low-mass dwarfs, this finding further expands our understanding of planetary systems in such stellar environments.

Global Positioning System

Context: The Global Positioning System (GPS) stands out among everyday technologies for its revolutionary impact across civilian, military, scientific, and urban domains, fundamentally reshaping our understanding of location and influencing various sectors worldwide.

What is the Global Positioning System (GPS)?

Overview:

• The GPS, established by the U.S. Department of Defense in 1973, comprises three primary components:
• Space: Involving the space segment, 24 satellites orbiting in six orbits ensure comprehensive global coverage, permitting receivers to access signals from at least four satellites simultaneously—an essential requirement for precise positioning.
  • All six orbits are positioned at an altitude of 20,200 km above Earth, with four satellites in each orbit at all times. Each satellite completes two orbits within a day.
• Control: The control segment, overseen by ground-based stations, monitors satellite performance and signal accuracy, adhering to the Standard Positioning Service (SPS) standards introduced in 2020. Key stations worldwide manage and maintain the system's integrity.
  • The SPS standard provides guidance to application developers and users worldwide on the GPS system's capabilities.
• User: The user segment spans various sectors, from agriculture to military operations, with an estimated 6.5 billion Global Navigation Satellite System (GNSS) devices globally in 2021, projected to rise to 10 billion by 2031, indicating its pervasive impact.

GPS Functionality:

• GPS operates through satellite-transmitted radio signals at specific frequencies (L1 and L2 frequencies at 50 bits/second), received and triangulated by GPS receivers, enabling precise determination of location in three dimensions of space and time.

Accuracy and Corrections:

• Error corrections, including relativistic effects on satellite clocks and relative velocities, are accounted for to enhance accuracy, highlighting the meticulousness of GPS calculations.
• Satellites maintain accurate time for GPS usage by employing atomic clocks, critical for preventing substantial location errors resulting from even minute timing discrepancies.

Do Other Countries Utilize GNSS?

• Numerous nations have established their independent Global Navigation Satellite Systems (GNSS) in addition to the GPS. Such systems are currently managed by Australia, China, the European Union (EU), India, Japan, South Korea, Russia, and the U.K.
  • Among these, Russia's GLONASS, the EU's Galileo, and China's BeiDou systems are globally operational.
• India introduced its indigenous Indian Regional Navigation Satellite System in 2006, later renamed Navigation with Indian Constellation (NavIC). Its space component comprises seven satellites: three in geostationary orbits and four in geosynchronous orbits.
  • As of May 2023, the minimum satellite number (four) facilitates ground-based navigation. The main control facilities are situated in Hassan, Karnataka, and Bhopal, Madhya Pradesh.
  • NavIC satellites utilize rubidium atomic clocks and transmit data in the L5 and S bands, with newer satellites also transmitting in the L1 band.
• India also manages the GPS-Aided Geo Augmented Navigation (GAGAN) system, developed and established by the Indian Space Research Organisation (ISRO) and the Airports Authority of India.
  • GAGAN's primary objective is to provide "safety-of-life civil aviation applications for the Indian airspace" and deliver "correction and integrity messages for GPS."

Fast Radio Bursts

Context: Scientists are currently exploring a new dimension of Fast Radio Bursts (FRBs), enigmatic radio signals originating from galaxies far away.

• The Laser Interferometer Space Antenna (LISA), slated for launch in the early 2030s, is poised to facilitate the investigation of FRBs and other enigmatic radio signals.

What are Fast Radio Bursts (FRBs)?

• Fast Radio Bursts (FRBs) are powerful and brief bursts of radio frequency emissions originating from deep space. These mysterious and intense signals last only milliseconds but release an amount of energy comparable to hundreds of millions of suns.
• Astronomers have proposed that magnetars, a type of neutron star formed from the remnants of exploding stars, could be a probable origin for FRBs.
• The rotation of magnetars is comparatively slower than that of other neutron stars.
• Neutron stars are formed when a massive star collapses. The very central region of the core collapses, crushing together every proton and electron into a neutron. These newly-created neutrons can stop the collapse, leaving behind a neutron star.
• A magnetar possesses a magnetic field over a thousand times stronger than that of other neutron stars, and it is a trillion times more powerful than Earth's magnetic field.

How Do Neutron Stars Play a Role in the Origin of FRBs?

• The genesis of Fast Radio Bursts (FRBs) could be associated with the collision involving two neutron stars.
• Such a collision event might produce two distinctive signals: gravitational waves, inducing distortions in space-time, and FRBs.
• Historically, the merging of neutron stars has been linked to accompanying electromagnetic signals.
• In a momentous discovery in 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) in the United States and the Virgo instrument in Italy detected gravitational waves emanating from the collision of two neutron stars.

Understanding Laser Interferometer Space Antenna (LISA)

• LISA represents a forthcoming space-based observatory dedicated to observing gravitational waves, jointly led by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA).
• Its design involves detecting and studying gravitational waves by gauging minute alterations in the distance between three spacecraft forming a triangular constellation, influenced by the passage of gravitational waves through the expanse of space.
• This space-centric observatory holds promise in offering invaluable insights into cosmic phenomena, such as the merging of colossal black holes and other celestial occurrences, thus enriching our comprehension of the cosmos.

What is LIGO?

About:

• LIGO stands for Laser Interferometer Gravitational-Wave Observatory.
• It is a groundbreaking observatory designed to detect and study gravitational waves.
• It is providing a new way to explore the universe by observing the ripples in space-time caused by events such as the collision of black holes or neutron stars.

First Detection of Gravitational Waves:

• The LIGO in the US first detected gravitational waves in 2015, which led to a Nobel Prize in Physics in 2017.
• These gravitational waves were produced by the merger of two black holes, which were about 29 and 36 times the mass of the Sun, 1.3 billion years ago.
• Black hole mergers are the source of some of the strongest gravitational waves.

Conclusion

Scientists are investigating Fast Radio Bursts (FRBs), brief and powerful signals from distant galaxies. Magnetars, dense remnants of exploded stars, are proposed sources. Neutron star collisions may generate both FRBs and gravitational waves, as observed by LIGO and Virgo. The upcoming Laser Interferometer Space Antenna (LISA) aims to deepen our understanding of cosmic phenomena.