The International Space Station is a home and laboratory. Astronauts live and work there while it orbits Earth. The station circles Earth at about 28,800 kilometers an hour. One circuit takes about 92 minutes. The astronauts see 16 sunrises and 16 sunsets every day. Astronauts and everything in the station float. The station is weightless inside. They float because they and the station are falling around Earth together. It is not because there is no gravity. Earth's gravity still pulls on the station. At that height it is only about 10 percent weaker than on the ground.
The station has six sleeping quarters, two bathrooms and a gym. Each crew member has an assigned cabin. Astronauts sleep in sleeping bags. In space, food floats, and astronauts need no plate to eat. The station cleans and recycles water from sweat and breath. Astronauts drink it. They grow plants in a small garden called Veggie. Space makes astronauts weaker. They exercise to keep their muscles and bones strong. They lose muscle mass in space faster than they would on Earth.
New NASA astronauts spend about two years learning basic astronaut skills. This is at Johnson Space Center. Astronaut training is long. Astronauts wear spacesuits for spacewalks, outside the station. Space is airless. It is dangerous without a spacesuit. A spacesuit backpack holds oxygen for astronauts to breathe. It removes the carbon dioxide they breathe out. Spacesuits protect astronauts from radiation and from bits of space dust. One kind of practice is spacewalks, in a huge pool of water. It is the closest you can get to microgravity on Earth.
A rocket lifts astronauts and their spacecraft off the ground. It burns fuel and pushes hot gas out of its engine. When the rocket pushes its exhaust out, the exhaust pushes the rocket the other way. Rocket scientists call this Newton's third law. For every action there is an equal and opposite reaction. A rocket engine carries everything it needs to burn its fuel. It can work in space, where there is no air.
On April 12, 1961, Yuri Gagarin became the first person to orbit Earth, in Vostok 1. His flight around Earth lasted 108 minutes. Valentina Tereshkova became the first woman in space on June 16, 1963. Sally Ride became the first American woman in space on June 18, 1983. Apollo 11 carried Neil Armstrong, Michael Collins and Buzz Aldrin. It launched on July 16, 1969. On July 20, 1969, Armstrong became the first person to walk on the Moon. Aldrin joined him. While they were on the Moon, Collins stayed in orbit in the command module Columbia.
Words to know
- orbits: circles around
- weightless: floating, no weight
- microgravity: almost no weight
- laboratory: science workplace
- radiation: harmful space rays
