Entries by Keshav Jain

Why does an astronaut seem weightless, while orbiting the Earth in space?

Actually, an astronaut orbiting the Earth in space is still firmly in the Earth’s gravitational field and seems weightless only because, he is moving in free fall i.e. in the same direction and at the same speed as the spacecraft.

1. Stationary Elevator.
2. Falling Elevator.
3. Spacecraft with engine on.
4. Spacecraft with engineer off.

  g :     Force of gravity.

  a :     Force of engine.

What are the main physical problems the astronauts face while remaining in space?

The lack of gravity in space tends to make the muscles weaker and the bones more porous, as comparatively less strength has to be used in space. This creates some problems on long space journeys and also when the astronauts return to Earth. Providing artificial gravity on spacecraft can solve this problem to a certain extent.

What is a spacewalk?

When astronauts go outside their spacecraft briefly in protective suits they are said to be taking a spacewalk. Actually they do not walk but drift beside the spacecraft.

What is an umbilical cord?

It is a safety cord which keeps the astronaut tethered to the spacecraft during a spacewalk. Without the umbilical cord, the spacewalking astronaut would drift away into space. It is called the umbilical cord as it is analogous to the umbilical cord that connects the unborn baby to its mother.

Who was the first man to walk in space?

In March 1965, the Russian cosmonaut Alexei Leonov left his spacecraft and performed the first spacewalk.