UPSC Prelims Current Affairs for 20 May 2026

Zwan-Wolf Effect Latest News

NASA's MAVEN spacecraft recently recorded something Mars has never shown before, which is the Zwan-Wolf effect.

About Zwan-Wolf Effect

• It is a process where charged particles are squeezed along magnetic structures, known as flux tubes. 
• The Zwan-Wolf effect was discovered in 1976 and has so far only been observed in planetary magnetospheres and not their atmospheres.  
• How does it happen?
  • The solar wind is a stream of charged particles flowing outwards from the sun.
  • As the solar wind nears the magnetic field of a planet, it becomes compressed near the magnetic boundaries. 
  • This creates a difference in pressure, or pressure gradient, that squeezes the charged particles along the magnetic field, away from the stream. 
  • As a result, closer to the stream is an area with a lower density of charged particles. This is called the Zwan-Wolf effect. 
  • On Earth, this mechanism deflects much of the solar wind and protects us from the Sun’s constant bombardment. 

Why are the New Findings Important?

• Unlike Earth, Mars is not protected by a global magnetic field, affecting how it interacts with the solar wind and space weather. 
• The Zwan-Wolf effect was observed in the ionosphere — deep within the Martian atmosphere below 200 km — which contains significant numbers of electrically charged particles. 
• The data showed that these charged particles were being squeezed and distributed around Mars’ atmosphere. 
• It suggests that Mars, despite lacking a global magnetic field, experiences similar interactions with the solar wind, offering valuable insights into the planet's atmospheric dynamics. 

Key Facts about MAVEN Spacecraft

• Mars Atmosphere and Volatile EvolutioN (MAVEN) is the first spacecraft mission dedicated to surveying the upper atmosphere of Mars.
• It is part of NASA’s Mars Exploration Program.
• It aims to understand the role that loss of atmospheric gas to space played in changing the Martian climate over time. 
• It was launched in November 2013 and arrived at Mars in September 2014.
• It carries three packages of instruments. 
  • One package studies the solar wind and its impact on Mars’s ionosphere. (Since Mars has no magnetic field, its atmosphere would be slowly removed by interaction with the solar wind.)
  • The second package is an ultraviolet spectrometer that studies the upper atmosphere.
  • The third package is a mass spectrometer that studies the composition of the upper atmosphere.
• MAVEN found that Mars lost about 2/3 of its early atmosphere to space.

Source: NDTV