UPSC CSE Prelims
International Space Programmes Previous Year Questions (PYQs)
Practice solved questions for International Space Programmes with detailed step-by-step solutions, key insights, and trend analysis for UPSC CSE PRELIMS.
Solved Previous Year Questions
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“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
Detailed Explanation:
Answer: Option 4 — Evolved LISA
The description of three spacecraft flying in an equilateral triangle formation with sides one million kilometres long, using lasers for measurement, uniquely identifies the Evolved Laser Interferometer Space Antenna (eLISA) mission. This is a proposed space-based gravitational wave observatory designed to detect low-frequency gravitational waves by measuring tiny distance changes between the spacecraft using laser interferometry. Voyager and New Horizons are single-spacecraft exploration missions, while LISA Pathfinder was only a technology demonstrator for testing eLISA components, not the full mission itself.
📝 Short Notes: Gravitational Wave Detection Missions
- LISA (Laser Interferometer Space Antenna): Original concept for space-based gravitational wave detection proposed by ESA and NASA.
- Evolved LISA (eLISA): Redesigned version with three spacecraft in equilateral triangle formation, each separated by ~1 million km, using laser interferometry to detect gravitational waves.
- LISA Pathfinder (2015-2017): Technology demonstration mission that successfully tested drag-free flight and precision measurement technologies required for eLISA.
- Configuration: Three identical spacecraft maintain precise formation while measuring distance changes of picometers (10⁻¹² meters) caused by passing gravitational waves.
- Target: Detection of low-frequency gravitational waves (0.1 mHz to 1 Hz) from sources like merging supermassive black holes, binary star systems, and early universe events.
- Ground-based counterpart: LIGO (Laser Interferometer Gravitational-Wave Observatory) detects high-frequency gravitational waves on Earth.
What is ‘Greased Lightning-10 (GL-10)’, recently in the news?
Detailed Explanation:
Answer: Option 1 — Electric plane tested by NASA
Greased Lightning-10 (GL-10) is an experimental hybrid-electric aircraft developed by NASA to test distributed electric propulsion and vertical take-off and landing (VTOL) capabilities.
The GL-10 is a subscale, remotely-piloted aircraft that can take off like a helicopter and transition to fixed-wing flight, demonstrating future applications in unmanned cargo transport and surveillance.
Which of the following pair is/are correctly matched?
| Spacecraft | Purpose |
|---|---|
| 1. Cassini-Huygens | Orbiting Venus and transmitting data to the Earth |
| 2. Messenger | Mapping and investigating the Mercury |
| 3. Voyager 1 and 2 | Exploring the outer solar system |
Select the correct answer using the code given below.
Detailed Explanation:
❌ Pair 1 – Incorrect: Cassini-Huygens was a mission to study Saturn and its moons (not Venus). The Huygens probe landed on Titan (Saturn's largest moon) in 2005.
✅ Pair 2 – Correct: MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) orbited Mercury from 2011 to 2015, mapping and studying its surface, composition, and magnetic field.
✅ Pair 3 – Correct: Voyager 1 and 2 were launched by NASA in 1977 to explore the outer solar system, providing data on Jupiter, Saturn, Uranus, and Neptune before entering interstellar space.
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