Space and Space Technology: UPSC Previous Year Questions (Science and Technology)

Explanation

Statement 1 is correct: GAGAN (GPS Aided GEO Augmented Navigation) is a Satellite-Based Augmentation System (SBAS) developed jointly by the Indian Space Research Organisation (ISRO) and the Airports Authority of India (AAI). Its primary objective is to provide satellite-based navigation services with enhanced accuracy and integrity, crucial for civil aviation applications. The system improves the accuracy of GPS signals, ensuring reliable and precise navigation over the Indian airspace.

Statement 2 is correct: GAGAN facilitates more uniform and high-quality air traffic management by providing accurate navigation services across the Indian Flight Information Region (FIR). This enhancement allows for improved air traffic control, efficient flight operations, and increased safety in the aviation sector.

Statement 3 is incorrect: While GAGAN was primarily developed for aviation, its applications extend beyond this sector. The system benefits other modes of transportation and sectors such as:

Maritime Navigation: Enhancing the safety and efficiency of ship movements. Railways: Improving train tracking and management systems. Road Transport: Assisting in vehicle navigation and traffic management. Agriculture: Supporting precision farming techniques. Disaster Management: Aiding in emergency response and resource deployment.

Explanation

Microgravity research refers to scientific studies conducted in environments where the force of gravity is extremely low, causing objects and people to appear weightless. In such conditions, often found in space or simulated on Earth, researchers can observe how physical, chemical, and biological systems behave differently than they do under normal gravity. Options 1, 2, and 3 are correct:

Axiom-4 is a private mission to the ISS that will conduct around 60 scientific studies, including several led by ISRO, with a strong focus on microgravity research across various disciplines such as biology, medicine, and materials science. ISRO and ESA are collaborating on microgravity research experiments specifically for Axiom-4. SpaDeX is an ISRO technology demonstrator for in-space docking. The mission uses the PSLV’s fourth stage (POEM-4) to carry 24 payloads from academia and startups, which will utilize the microgravity environment in orbit for scientific experiments. The mission explicitly provides opportunities for in-orbit microgravity experiments for extended durations. Gaganyaan is India’s first human spaceflight mission, led by ISRO. Scheduled to send Indian astronauts into low Earth orbit, it aims to demonstrate indigenous capability in crewed space missions. Gaganyaan will also facilitate scientific research in microgravity, marking a significant milestone in India’s space exploration journey.

Explanation

Stars are classified based on their size, mass, and brightness into categories such as giant stars and dwarf stars. Giant stars are massive, highly luminous stars that burn They are often in the later stages of stellar evolution. Dwarf stars, on the other hand, are smaller, less luminous, Red dwarfs, the most common type, can burn for trillions of years, while white dwarfs are the remnants of low to medium-mass stars after they exhaust their nuclear fuel.

Statement I is incorrect: Giant stars have much shorter lifespans than dwarf stars. Giant stars burn fuel quickly because of their high mass and energy, while red dwarf stars use fuel slowly, allowing them to last billions or even trillions of years.

Statement II is correct: Giant stars have much higher core temperatures and pressures, leading to faster nuclear fusion rates compared to dwarf stars. This high rate of fusion results in a shorter lifespan.

Explanation

Pair 1 is not correct: Cepheids, also known as Cepheid Variables, are stars that periodically brighten and dim. Due to their behaviour, these objects can function as cosmic indicators, extending their usefulness as yardsticks for distances up to several tens of millions of light-years away, owing to a consistent relationship between their brightness and other factors.

Pair 2 is not correct: A nebula is a very large cloud of gas and dust in outer space. A dead star’s explosion, such as a supernova, releases gas and dust, which in turn forms certain nebulae (more than one nebula). Other nebulae are places where brand-new stars are only starting to develop. It is for this reason that some nebulae are referred to as "star nurseries."

Pair 3 is correct: Pulsars are extremely compact, rapidly km (12 miles). They are virtually entirely made of neutrons that are formed when massive stars run out of fuel and collapse.

Explanation

The term "Global Navigation Satellite System" (GNSS) encompasses any satellite network offering positioning, navigation, and timing (PNT) services either globally or within specific regions.The Quasi-Zenith Satellite System (QZSS) stands as a regional GNSS owned by the Government of Japan, aiming to bolster coverage in East Asia and Oceania while complementing GPS.

Explanation

A solar storm is a disturbance on the Sun that can release a burst of energy and particles into space. These eruptions, such as solar flares and coronal mass ejections, can impact Earth by disrupting communication systems, damaging satellites, and even causing power outages. Statements 1 and 7 are correct: These solar explosions propel bursts of particles and electromagnetic fluctuations into Earth’s atmosphere that could lead to the malfunction of satellites, which might impact high-frequency communication blackouts, satellite anomalies, GPS scintillations, airline communication.

Statement 2 is incorrect: Solar storms affect the Earth’s magnetosphere and ionosphere but do not directly cause tsunamis, which are triggered by seismic activity, underwater landslides, or volcanic eruptions.

Statement 3 is correct: The solar explosions propel bursts of particles and electromagnetic fluctuations into Earth’s atmosphere that could destroy transformers in power systems.

Statement 4 is correct: Energy, radiation and high energy particles emitted by solar flares can trigger intense lights in the sky, called Auroras.

Statement 5 is incorrect: Flares are electromagnetic radiation bursts rather than actual fires. They won’t start forest fires as a result. While they release high-energy radiation, it does not directly ignite fires on Earth.

Statement 6 is correct: Particles from a CME can potentially collide with a satellite’s critical electronics, causing the satellite’s systems to malfunction.

Explanation

Astronomical distances are measured in light-years to effectively express the vast distances in space using a consistent and universal unit. A light-year represents the distance light travels in one year in a vacuum, which is approximately 9.46 trillion kilometers (5.88 trillion miles). Astronomers calculate the distances of stars and other celestial objects in the time it takes for light to reach us since estimating distances in miles or kilometres is inadequate on the cosmological scale. Since the speed of light is known to be constant throughout the universe and for high precision, astronomical distances are expressed in terms of light-years. The fastest light can move is in vacuum.

Explanation

Evolved LISA (eLISA) is a planned mission by the ESA for gravitational wave detection. It will detect minute distortions in space-time caused by gravitational waves. Lasers will shine between the spacecraft to measure changes in distance. Two "Daughter" spacecraft and a "Mother" spacecraft make up the eLISA mission. These will form a triangle orbit around the Sun. The two Daughter spacecraft will be joined to the Mother satellite, and the three satellites will form a precision interferometer by 1 million km long laser beams. Options (a), (b) and (c) are incorrect:

Voyager-2: A NASA spacecraft that studied Jupiter, Saturn, Uranus, and Neptune. It was not intended for gravitational wave detection. New Horizons: The first mission to explore Pluto and the Kuiper Belt, focused on planetary exploration rather than detecting gravitational waves. LISA Pathfinder: It was the precursor mission of eLISA that successfully demonstrated the technology required for a space based gravitational wave observatory.

Explanation

Option (b) is correct: The LIGO detectors detected the first gravitational waves produced by two giant merging blackholes in 2016. Gravitational waves are ripples in spacetime’s fabric brought on by cosmic catastrophes like neutron stars or black hole collisions. These disturbances are incredibly powerful, yet their signals are feeble and difficult to detect when they travel through distant regions of space and time. In other words, it took that long for the signals to reach Earth. As a result, the observatory provides a chance to go back in time and solve puzzles about the origins of the universe. Options (a), (c) and (d) are incorrect:

A wormhole is a hypothetical structure that connects dispersed places in spacetime. It is based on a unique solution to the Einstein field equations. It is also known as an Einstein-Rosen bridge or wormhole. Although wormholes are consistent with the general theory of relativity, it is yet unknown whether they truly exist. The Higgs field, one of the fields in particle physics theory, undergoes quantum excitation to form the Higgs boson, an elementary particle in the Standard Model of particle physics. The Higgs particle is a large scalar boson with no electric charge, colour, or spin in the Standard Model. A gravitational singularity, or spacetime singularity, is a point where the values used to describe the gravitational field become infinitely large, regardless of the coordinate system used. At this point, the distinction between physical laws breaks down, and space and time lose their independent identities, merging into an indistinguishable and undefined state.

Explanation

General theory of relativity, is a geometric theory related to gravitation published by Albert Einstein in 1915 and currently defines gravitation in modern physics. A coherent account of gravity as a geometric property of space and time, or four-dimensional spacetime, is provided by general relativity, which generalises special relativity and improves Newton’s law of universal gravitation. In particular, the energy and momentum of all matter and radiation present have a direct relationship to the curvature of spacetime.

Statement 1 is correct: According to General Relativity, light travels along the curved spacetime shaped by the gravity of massive objects. This phenomenon, known as gravitational lensing, has been observed in effects such as Einstein’s Cross and the bending of starlight around the Sun.

Statement 2 is correct: General Theory of Relativity showed that space and time are malleable or flexible, and predicted that our universe was ever expanding.

Statement 3 is correct: The theory of relativity states that massive objects distort spacetime around it. And since photons travel the shortest distance between two points, light appears to be bent when it travels through the distorted spacetime of a massive object.