Previous Year Question
What is the purpose of the ‘evolved Laser Interferometer Space Antenna (eLISA)’ project?
To detect neutrinos
To detect gravitational waves
To detect the effectiveness of missile defence system
To study the effect of solar flares on our communication systems
Correct Answer: B
Detailed Solution
eLISA stands for the Evolved Laser Interferometer Space Antenna. Its purpose is to detect and accurately measure gravitational waves from space.
Gravitational waves are extremely minute ripples in space-time. They are produced by the accelerated motion of massive objects—such as the merger of massive black holes, compact binary systems and other highly energetic astronomical events.
Under the present LISA concept, three spacecraft will orbit the Sun while flying in a triangular formation. Laser beams will be transmitted between the spacecraft.
When a gravitational wave passes through this formation, it will produce an extremely minute change in the distances between the spacecraft. Laser interferometry will measure this change to determine the existence, source and characteristics of the gravitational wave.
Placing the detector in space provides the special advantage of avoiding the effects of the Earth’s seismic vibrations, human activities and local gravitational disturbances. Its extremely long laser arms will enable LISA to detect low-frequency gravitational waves that cannot easily be detected by ground-based detectors.
In its present form, the mission is called LISA. According to the European Space Agency, it will comprise three spacecraft and six laser beams, and its launch is planned for 2035.