Life in Space

A free interactive lesson on life in space for Class 5 — why astronauts on the ISS float (the station is in freefall, not zero gravity), how they sleep strapped in bags, eat from pouches, and why they exercise two hours daily to prevent bone loss. Based on NCERT Class 5 Space. Includes quiz.

Class 5 ScienceClass 5 / Grade 5Ages 7–10
Lesson
🧑‍🚀 Life in Space
In space, everything floats. Why?International Space Station🧑‍🚀floating!The ISS is in freefall — so everything inside floats.

Astronauts on the International Space Station float around inside — they don't walk, they drift. Food floats, water forms spherical bubbles, and you have to strap yourself into a sleeping bag to stop drifting into the walls at night. This state is called weightlessness, and it changes everything about daily life.

The International Space Station

The International Space Station (ISS) is a habitable space station orbiting Earth at about 400 km altitude. It travels at about 28,000 km/h — completing one orbit every 90 minutes. Up to seven astronauts live and work there at a time, conducting science experiments in the unique microgravity environment.

India's Sunita Williams served two long-duration missions on the ISS (2006–2007 and 2012), and has been a prominent example of life and work in space for Indian students.

Why do astronauts float — the real reason

Many people think astronauts float because there is no gravity in space. This is wrong. The ISS is only 400 km above Earth — gravity there is still about 90% as strong as on the surface. Astronauts float because of freefall.

The ISS is constantly falling towards Earth due to gravity, but it's also moving sideways so fast (28,000 km/h) that it keeps missing the planet — this is an orbit. Since both the station and the astronauts inside are falling at exactly the same rate, there is nothing pushing the astronauts against the floor. Without that push, they feel weightless and float.

Daily life in weightlessness

  • Sleeping — astronauts sleep in sleeping bags strapped to the wall. Without strapping in, they would float around and bump into things.
  • Eating — food comes in sealed pouches. Floating crumbs could enter equipment or eyes, so crumbly foods like bread are avoided. Water doesn't flow downward — it forms floating spherical balls and must be sucked through straws.
  • Bathing — there are no showers. Astronauts squeeze water onto their skin and wipe it off with a cloth. Water doesn't drain — it floats in blobs.
  • Going to the toilet — a vacuum toilet system sucks waste away. Astronauts must align carefully and strap in.

Exercise — 2 hours every day

Without gravity's constant resistance, muscles have nothing to work against and quickly weaken. Bones lose density because they no longer need to support the body's weight. Astronauts on long missions can lose up to 20% of their muscle mass and 1–2% of their bone density per month.

To counteract this, astronauts exercise for two hours every day using specially designed equipment — a treadmill with harnesses to push them down, a stationary cycle, and a resistance machine. Despite this, returning astronauts still need months of rehabilitation on Earth.

Frequently asked questions

Why do astronauts float in the ISS?

Because the ISS is in freefall — it's falling towards Earth but moving sideways so fast it keeps missing the planet (orbiting). Both the station and the astronauts fall at the same rate, so there's nothing pushing the astronauts against the floor. They float, but gravity is still there.

Is there no gravity in space?

No — gravity exists everywhere. At the ISS's altitude of 400 km, gravity is still about 90% as strong as on Earth's surface. Astronauts feel weightless because of freefall, not because gravity has disappeared.

Why do astronauts exercise 2 hours a day?

Without gravity's resistance, muscles weaken and bones lose density rapidly. Astronauts can lose up to 20% of muscle mass on long missions. Daily exercise (treadmill, cycling, resistance training) slows this loss, though rehabilitation is still needed after returning to Earth.

How do astronauts drink water in space?

Water doesn't flow downward in the ISS — it forms floating spherical blobs. Astronauts drink from sealed pouches through straws. If water escapes, they catch the floating blobs or they can damage equipment.

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