Question 19 from UPSC CSE 2020 - S&T

Question

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

A

Voyager-2

B

New Horizons

C

LISA Pathfinder

D

Evolved LISA

IASCODEX · Accepted Answer

Correct Option: D. Evolved LISA

Strategy: The strategy focuses on identifying unique features: three spacecraft in an equilateral triangle formation, each side one million kilometers, and the use of lasers. Other missions like Voyager-2, New Horizons, and LISA Pathfinder are eliminated due to their distinct configurations (single-probe, planetary missions, or much shorter baselines). Only Evolved LISA (eLISA) perfectly matches this specific configuration for space-based gravitational wave detection.

Key Info: ## About LISA (Evolved Laser Interferometer Space Antenna)

The Evolved Laser Interferometer Space Antenna (eLISA, now commonly referred to as LISA) is a planned European Space Agency (ESA) space-based gravitational wave observatory. It will consist of three spacecraft arranged in an equilateral triangle, with each side spanning about one million kilometers. These spacecraft will utilize laser interferometry to precisely measure variations in the distances between free-floating test masses housed in each satellite.

The project aims to detect low-frequency gravitational waves originating from massive astrophysical sources such as merging supermassive black holes and binary star systems. These phenomena are not detectable by ground-based observatories like LIGO.

LISA Pathfinder was its precursor, demonstrating key technologies with a much shorter baseline. In contrast, Voyager-2 and New Horizons are planetary exploration missions belonging respectively to NASA's Voyager and New Frontiers programs, entirely unrelated to gravitational wave research or multi-spacecraft laser interferometry configurations.

IASCODEX · Answer

Option A: Voyager-2

IASCODEX · Answer

Option B: New Horizons

IASCODEX · Answer

Option C: LISA Pathfinder