Spacewalk:

• It is an extravehicular activity (EVA) i.e. a period of activity spent outside a spacecraft by an astronaut in space.
• The first spacewalk was carried out in 1965, by the Soviet cosmonaut Alexei Leonov.
• Spacewalks are done to carry out science experiments. Astronauts can attach experiments to the outside of a spacecraft during their spacewalk, and observe how the space environment impacts different things. Astronauts can also test new equipment, and repair satellites or their spacecraft during the walk.

Van Allen Belt:

• The Earth’s magnetosphere traps the high energy radiation particles and shields the Earth from the solar storms and the constantly streaming solar wind that can damage technology as well as people living on Earth. These trapped particles form two belts of radiation, known as the Van Allen Belts, that surround the Earth like enormous donuts. 
• The outer belt is made up of billions of high-energy particles that originate from the Sun. Situated at altitudes ranging from 15,000 to 20,000 km. above the Earth’s surface
• The inner belt results from interactions of cosmic rays with Earth’s atmosphere. Located between 680 and 3,000 km. above the Earth’s surface
• Astronauts must fly though the Van Allen Belts to reach outer space, so it is important to fly through this region quickly to limit their exposure to radiation.