UPSC Prelims 2017 Question:

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

Explanation: 

• The evolved Laser Interferometer Space Antenna (eLISA) is a mission aiming at exploring the Gravitational Universe from space for the first time. It involves scientists from eight European countries, Denmark, France, Germany, Italy, The Netherlands, Spain, Switzerland, and the UK, as well as the support of several US-based ones.
  
  
• The eLISA mission consists of a “Mother” and two “Daughter” spacecrafts. These will orbit the Sun in a triangular configuration. The three satellites will form a precision interferometer, with the two Daughter spacecrafts connected to the Mother one by 1 million km long laser beams. This interferometer will be capable of detecting gravitational waves at frequencies in the range of 0.1 mHz to 1 Hz. Such a frequency interval is not accessible on Earth due to arm length limitations and to noise caused by the terrestrial gravity gradient noise. In this sense, eLISA will complement the efforts of ground-based gravitational-wave detectors.
  
  

Therefore, option (2) is the correct answer.

Subject: Science & Technology | Space and Related Developments