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GS Paper IUPSC Prelims 2020
Space & ISRO
Question No. 104Interactive Test Mode
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Q104. "The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometers long, with lasers shining between the craft." The experiment in question refers to

"The experiment will employ a trio of spacecraft flying in formation in the shape of an equilateral triangle that has sides one million kilometers long, with lasers shining between the craft." The experiment in question refers to

Select the correct option below (or cross out options to eliminate)
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Official Answer Key & Detailed Solution

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Official UPSC Answer KeyUPSC Prelims 2020 • Science and Technology

Correct Answer: Option (D) — Evolved LISA

Concept & Option Breakdown

Standard Reference Verified

Option D is correct: The evolved Laser Interferometer Space Antenna (eLISA / LISA) is an ESA-led space mission designed to detect low-frequency gravitational waves using three spacecraft flying in an equilateral triangular constellation separated by million-kilometer laser links.

LISA Pathfinder was a single-spacecraft technology testbed precursor, while Voyager-2 and New Horizons were planetary exploration probes.

Elimination Heuristic & Exam Approach

The question describes the full operational constellation ('trio of spacecraft... one million kilometers long'), which refers to the full-scale observatory mission eLISA rather than the precursor single-satellite demonstrator LISA Pathfinder.

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Question Specifications & Syllabus Mapping

Examination & YearUPSC Civil Services Preliminary Examination 2020 (Q104)
Paper & Marking SchemeGS Paper I • 2 Marks (-0.66 Negative for incorrect response)
Syllabus Subject & TopicScience and Technology → Space & ISRO
Official Answer KeyOption (D) — Evolved LISA

Related & Repeated Prelims PYQs (1)

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2017 • Q10984% Match

What is the purpose of the ‘evolved Laser Interferometer Space Antenna (eLISA)’ project?

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Frequently Asked Questions — UPSC Prelims 2020 Q104

What is the official answer for UPSC Prelims 2020 GS Paper I Question 104 (Science and Technology)?

The official UPSC answer key for this 2020 Science and Technology (Space & ISRO) question is Option (D): "Evolved LISA". Correct attempts carry 2 Marks with -0.66 Negative penalty for wrong answers.

Which UPSC Prelims syllabus topic does this 2020 question belong to?

This question belongs to GS Paper I under the subject "Science and Technology" and micro-topic "Space & ISRO". You can explore all repeated questions from Space & ISRO in Acme AI's 3D Prelims PYQ Realm or practice 50 full-length and sectional tests in the APT Prelims Test Series.

How can I solve this Space & ISRO UPSC Prelims question using option elimination?

The question describes the full operational constellation ('trio of spacecraft... one million kilometers long'), which refers to the fullscale observatory mission eLISA rather than the precursor singlesatellite demonstrator LISA Pathfinder.

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