Previous Year Question
“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 the question refers to
Voyager-2
New Horizons
LISA Pathfinder
Evolved LISA
Correct Answer: D
Detailed Solution
The experiment described in the question refers to the Evolved Laser Interferometer Space Antenna (eLISA). Its purpose is to detect and measure gravitational waves in space.
Its concept involves placing three spacecraft in a formation resembling an equilateral triangle. The spacecraft exchange laser beams with one another.
When a gravitational wave passes through this formation, it produces an extremely minute change in the distances between the spacecraft. This change is measured through laser interferometry to detect gravitational waves.
LISA Pathfinder is not the correct answer. It was not a gravitational-wave observatory but a technology-demonstration mission that tested the technologies required for the future LISA mission. It consisted of one spacecraft, and its mission was completed in 2017.
Voyager-2 is a mission for studying the outer planets and the heliosphere, whereas New Horizons studied Pluto and Kuiper Belt objects. Therefore, neither is associated with this laser-interferometry experiment.
The fundamental concept of three spacecraft and laser interferometry continues in the present LISA design. According to the European Space Agency, its launch is planned for 2035.