Space and Defence Technology important part of science and its syllabus. Previous Year Question (PYQ) papers are invaluable resources for aspirants preparing for competitive exams like the Union Public Service Commission (UPSC) examinations. In this article we present important PYQ on Space and Defence Technology.
PYQ on Space and Defence Technology
Q- Which one of the following statements best reflects the idea behind the “Fractional Orbital Bombardment System” often talked about in media? (2022)
(a) A hypersonic missile is launched into space to counter the asteroid approaching the Earth and explode it in space.
(b) A spacecraft lands on another planet after making several orbital motions.
(c) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
(d) A spacecraft moves along a comet with the same surface. speed and places a probe on its
Answer- Option C
EXPLANATION
The concept behind the Fractional Orbital Bombardment System (FOBS) involves placing a warhead into a stable orbit and then deorbiting it over the intended target. By aligning the target with the launch position, the warhead completes a circular trajectory as it orbits the Earth. Despite the Earth’s movement during this process, the warhead’s horizontal movement is adjusted to ensure it passes over the target. Essentially, this method allows a missile to be directed straight to the target or launched in the opposite direction, circling the planet before reaching the target from the opposite direction.
Q- Which one of the following is a reason why astronomical distances are measured in light-years? (2021)
(a) Distance among stellar bodies do not change
(b) Gravity of stellar bodies does not change
(c) Light always travels in straight line
(d) Speed of light is always same
Answer- Option D
EXPLANATION
A light-year represents the distance that light travels in one year, equivalent to approximately 5.88 trillion miles (9.46 trillion kilometers). Light moves swiftly through interstellar space at a constant speed of about 186,000 miles (300,000 kilometers) per second.
The use of light-years for measuring astronomical distances is preferred because conventional units like kilometers and miles are inadequate for conveying the immense scale of the universe. Moreover, the speed of light, which serves as the basis for this measurement, remains both finite and consistent, with a value of approximately 2.998 x 10^8 meters per second. Hence, option 4 is the correct choice.
Q- The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometres long, with lasers shining between the craft.” The experiment in question refers to (2020)
(a) Voyager-2
(b) New Horizons
(c) LISA Pathfinder
(d) Evolved LISA
Answer- Option D
EXPLANATION
LISA, short for Laser Interferometer Space Antenna, is a space-based observatory designed to detect gravitational waves using laser interferometry. The system comprises three spacecraft placed in heliocentric orbit, with each arm extending over a million kilometers. eLISA, a mission geared towards exploring the Gravitational Universe from space, involves collaboration among scientists from eight European countries including Denmark, France, Germany, Italy, The Netherlands, Spain, Switzerland, and the UK, along with support from several organizations based in the US.
Q- Recently, scientists observed the merger of giant ‘blackholes’ billions of light-years away from the earth. What is the significance of this observation? (2019)
(a) ‘Higgs boson particles’ were detected.
(b) ‘Gravitational waves’ were detected.
(c) Possibility of intergalactic space travel through ‘wormhole’ was confirmed.
(d) It enabled the scientists to understand ‘singularity’.
Answer- Option B
EXPLANATION
Millions of light-years distant from Earth, a collision occurred between two black holes, resulting in the formation of a larger one. Gravitational waves are generated when two black holes orbit and combine. The resultant black hole has a mass exceeding 80 times that of the Sun. The energy released during this process takes the form of gravitational waves as the two black holes gradually drew closer to each other.
Q- Consider the following phenomena (2018)
(1) Light is affected by gravity.
(2) The Universe is constantly expanding.
(3) Matter warps its surrounding space-time.
Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media ?
(a) 1 and 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer- Option D
EXPLANATION
Gravitational lensing is a phenomenon where the bending of light by gravity results in the appearance of multiple images of a distant celestial object in the sky. Albert Einstein first proposed the concept of gravitational waves in 1916 as part of his general theory of relativity.
According to Einstein, gravity is the result of the curvature of both space and time caused by massive objects. In 1917, Einstein extended his theory to describe the structure of the entire universe. He concluded that his equations predicted either a contracting or expanding universe, which was not supported by observational evidence at the time.
To account for this, Einstein introduced the cosmological constant to maintain a static universe. This adjustment resulted in a model known as Einstein’s world or Einstein’s static universe, where the universe was hypothesized to be stable and closed in curvature based on his interpretation of Mach’s principle.
Q- With reference to the Indian Regional Navigation Satellite System (IRNSS), consider the following statements : (2018)
(1) IRNSS has three satellites in geostationary and four satellites in geosynchronous orbits.
(2) IRNSS covers entire India and about 5500 sq. km beyond its borders.
(3) India will have its own satellite navigation system with full global coverage by the middle of 2019.
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) None
Answer- Option A
EXPLANATION
IRNSS, comprising eight satellites forming the NavIC constellation, includes three satellites positioned in geostationary orbit and four in geosynchronous orbits. Its primary objective is to deliver precise position information services within India and up to 1500 km beyond its borders. Thus, Statement 2 is inaccurate.
An Extended Service Area extends beyond the primary service area and spans between latitudes 30 degrees South and 50 degrees North, and longitudes 30 degrees East to 130 degrees East. IRNSS offers two service types: the Standard Positioning Service (SPS), accessible to all users, and the Restricted Service (RS), which is encrypted and exclusive to authorized users.
The applications of IRNSS encompass terrestrial, aerial, and marine navigation, disaster management, vehicle tracking, integration with mobile phones, precise timing, mapping, geodetic data capture, terrestrial navigation for hikers and travelers, and visual and voice navigation for drivers.
Q- With reference to India’s satellite launch vehicles, consider the following statements: (2018)
(1) PSLVs launch satellites useful for Earth resources monitoring whereas GSLVs are designed mainly to launch communication satellites.
(2) Satellites launched by PSLV appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth.
(3) GSLV Mk III is a four-staged launch vehicle with the first and third stages using solid rocket motors; and the second and fourth stages using liquid rocket engines.
Which of the statements given above is/are correct.?
(a) 1 only
(b) 2 and 3
(c) 1 and 2
(d) 3 only
Answer- Option A
EXPLANATION
The Polar Satellite Launch Vehicle (PSLV) serves as India’s third-generation launch vehicle and has earned the moniker “Workhorse of ISRO” due to its consistent success in delivering various satellites into Low Earth Orbits. It is a four-stage launch vehicle, with its second and fourth stages employing liquid rocket engines, while the first and third stages utilize solid rocket motors. PSLV is specifically engineered to deploy earth-observation or remote-sensing satellites weighing up to approximately 1750 Kg into Sun-Synchronous circular polar orbits ranging from 600 to 900 Km altitude.
On the other hand, the Geosynchronous Satellite Launch Vehicle (GSLV) is designed and operated by ISRO with a primary focus on delivering communication satellites. GSLV Mk 3, a three-stage heavy lift launch vehicle, features two solid strap-on boosters, a core liquid booster, and a cryogenic upper stage. Its capability enables it to transport satellites weighing up to four tons to Geosynchronous Transfer Orbit (GTO) or approximately 10 tons to Low Earth Orbit (LEO). The geosynchronous nature of satellites placed in these orbits ensures that they appear fixed in the same position in the sky when observed from a specific location on Earth.
Q- The terms ‘Event Horizon’, ‘Singularity’, `String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of (2017)
(a) Observation and understanding of the Universe
(b) Study of the solar and the lunar eclipses
(c) Placing satellites in the orbit of the Earth
(d) Origin and evolution of living organisms on the Earth
Answer- Option A
EXPLANATION
The standard model of particle physics is a mathematical framework that explains electromagnetism, the strong and weak nuclear forces, and the Higgs mechanism. String theory is a concept in quantum physics aimed at comprehending quantum phenomena. A black hole is fundamentally characterized by a singularity obscured by an event horizon, where the escape velocity surpasses the speed of light, leading to objects being permanently trapped. Thus, all these terms are associated with the observation and comprehension of the universe.
Q- With reference to `Astrosat’, the astronomical observatory launched by India, which of the following statements is/are correct? (2016)
(1) Other than the USA and Russia, India is the only country to have launched a similar observatory into space.
(2) Astrosat is a 2000 kg satellite placed in an orbit at 1650 km above the surface of the Earth.
Select the correct answer using the code given below.
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer- Option D
EXPLANATION
Astrosat stands as India’s pioneering multi-wavelength space observatory, distinguishing itself by facilitating simultaneous observations across various wavelengths using a single satellite. Contrary to statement 2, Astrosat, weighing approximately 1513 kg, was launched into a 650 km orbit by the PSLV-C30, dismissing its inaccuracy. Statement 1 is refuted as well; preceding India, space agencies such as NASA, the European Union, Japan, and Russia had already deployed similar facilities into space.
The scientific goals of the Astrosat mission encompass comprehending high-energy phenomena within binary star systems housing neutron stars and black holes, estimating magnetic fields of neutron stars, investigating star birth regions and high-energy processes in systems beyond our galaxy, identifying new transient X-ray sources, and conducting a limited deep field survey of the Universe in the Ultraviolet region.
Q- Consider the following statements: The Mangalyaan launched by ISRO (2016)
(1) is also called the Mars Orbiter Mission
(2) made India the second country to have a spacecraft orbit the Mars after USA
(3) made India the only country to be successful in making its spacecraft orbit the Mars in its very first attempt
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer- Option C
EXPLANATION
Mangalyaan, also known as the Mars Orbiter Mission, was launched on November 5, 2013, by ISRO, making India the first Asian country to successfully insert a spacecraft into Mars’ orbit on its maiden attempt. The primary objective of the mission is to study methane levels in the Martian atmosphere. This achievement marked India’s distinction as the fourth space agency globally, after the Soviet space program, NASA, and the European Space Agency, to send a satellite to Mars. Therefore, statements 1 and 3 are correct, while statement 2 is incorrect.
Q- In which of the following activities are Indian Remote Sensing (IRS) satellites used? (2015)
(1) Assessment of crop productivity
(2) Locating ground water resources
(3) Mineral exploration
(4) Telecommunications
(5) Traffic studies
Select the correct answer using the code given below
a) 1, 2 and 3 only
b) 4 and 5 only
c) 1 and 2 only
d) 1, 2, 3, 4 and 5
Answer- Option A
EXPLANATION
The initiation of remote sensing in India can be traced back to the launch of the Bhaskar 1 satellite in 1979, marking the beginning of this era. Following this, Bhaskar 2 was launched in 1981. However, it was the successful deployment of the IRS 1A satellite in 1988 that formally established the Indian Remote Sensing satellite system. Today, the Indian Remote Sensing satellite constellation stands as the largest civilian network of its kind globally. Offering diverse capabilities, it delivers imagery with varying levels of spatial, spectral, and swath resolutions. Utilized across a wide spectrum of applications, these satellites aid in tasks such as crop area estimation, drought monitoring, flood risk assessment, and hydro-geomorphologic mapping for identifying subterranean water resources. Additionally, they facilitate land use mapping, forest surveys, coastal studies, environmental impact analysis, and wetland mapping, among other purposes.
Q- In the context of modern scientific research, consider the following statements about ‘IceCube’, a particle detector located at South Pole, which was recently in the news : (2015)
(1) It is the world’s largest neutrino detector, encompassing a cubic kilometre of ice.
(2) It is a powerful telescope to search for dark matter
(3) It is buried deep in the ice.
Which of the statements given above is/are correct?
a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3 only
Answer- Option D
EXPLANATION
The IceCube Neutrino Observatory, also known as IceCube, stands as the pioneering detector of its kind, specifically engineered to observe celestial phenomena from the depths of the Antarctic ice at the South Pole. This validates Statement 1.
The scientific research at IceCube is conducted by an international consortium of scientists known as the IceCube Collaboration, comprising around 300 physicists from 53 institutions across 12 nations. The University of Wisconsin–Madison spearheads the operation and maintenance of the detector, while the global team oversees the scientific endeavors, with many members contributing to its design and construction. This affirms Statement 3. IceCube, covering a volume of one cubic kilometer within the ice, is dedicated to detecting neutrinos, which are nearly massless subatomic particles. These neutrinos serve as invaluable messengers from high-energy astrophysical sources such as supernovae, gamma-ray bursts, and phenomena involving black holes and neutron stars, confirming Statement 2.
IceCube, along with its surface array IceTop and the dense infill array DeepCore, serves as a versatile experiment, addressing fundamental questions in physics like dark matter and neutrino properties. This underscores Statement 2. Additionally, IceCube monitors cosmic rays interacting with Earth’s atmosphere, revealing perplexing structures yet to be fully understood. Ongoing research efforts by the collaboration are unlocking new avenues for exploring the universe, echoing the sentiments expressed in the provided statements.
Q- Which of the following pair(s) is/are correctly matched? (2014)
| Spacecraft | Purpose |
| Cassini-Huygens | Orbiting the Venus and transmitting data to the Earth |
| Messenger | Mapping and investigating the Mercury |
| Voyager | Exploring the outer solar system |
Select the correct answer using the code given below.
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer- Option B
EXPLANATION
The Cassini-Huygens mission marked the fourth space probe dispatched to Saturn. Comprising the Cassini orbiter and the Huygens probe, it commenced its journey to Saturn and arrived at the planet in July 2004. Its objectives encompassed studying various aspects of Saturn, including the dynamics of its rings and its atmospheric conditions at cloud level, among other scientific goals.
Messenger, the seventh Discovery-class mission, became the inaugural spacecraft to orbit Mercury, aiming to analyze the planet’s geology, magnetic field, and chemical composition primarily.
Launched in 1977, Voyager 1 and 2 embarked on their missions primarily to explore Jupiter and Saturn. Voyager 2 extended its exploration to Uranus and Neptune subsequently. Both spacecrafts ventured into interstellar space, probing the outer boundary of the heliosphere.
Q- Which reference to Agni-IV Missile, which of the following statements is/are correct? (2014)
(1) It is a surface-to-surface missile.
(2) It is fuelled by liquid propellant only.
(3) It can deliver one-tonne nuclear warheads about 7500 km away.
Select the correct answer using the code given below.
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer- Option A
EXPLANATION
The Agni-IV Missile, classified as a nuclear-capable long-range ballistic missile, possesses a strike range extending to 4,000 km, rendering Statement 3 inaccurate.
Employing a two-stage solid propellant system, it deviates from Statement 2, which is incorrect. Serving as a surface-to-surface missile, it aligns with Statement 1, which is deemed correct. Measuring 20 meters in length and weighing 17 tonnes, it is the fourth installment in the Agni series of missiles and has the capacity to deliver one-tonne nuclear warheads.
Q- The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is/are the importance/ importance of discovering this particle? (2013)
- It will enable us to under- stand as to why elementary particles have mass.
- It will enable us in the near future to develop the technology of transferring matter from one point to another without traversing the physical space between them.
- It will enable us to create better fuels for nuclear fission.
Select the correct answer using the codes given below.
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer- Option A
EXPLANATION
The Higgs particle, famously discovered by British physicist Peter Higgs during the 1960s, is also referred to as the “God Particle.” Its discovery was pivotal in understanding the origin of mass in elementary particles. The Higgs-Boson particle is a component of the invisible energy field known as the Higgs field, which permeates the universe. As a fundamental particle, it imparts mass to other particles, thereby contributing to the formation of celestial bodies like stars and planets. The absence of mass provided by the Higgs field would result in the absence of gravity and consequently, life.