How much does a spacecraft weigh in space?
A spacecraft in orbit has been said to be in a state of weightlessness -- but the preferred term today is microgravity. Microgravity results from giving a spacecraft enough forward velocity to counter-balance the downward pull of gravity. Another way to look at it is that a spacecraft in a circular orbit is always falling toward Earth, because Earth's gravity is pulling on it, but its forward speed is enough to keep it the same distance above the surface. Everything in or near the spacecraft is also operating in microgravity. A spacecraft on a long voyage between planets is actually in orbit around the sun, where its forward velocity counters the Sun's gravity in the same manner that a satellite orbits the Earth.

What is the Space Shuttle's speed and altitude?
The speed of a Space Shuttle in low Earth orbit is about 17,500 miles an hour. An orbiter can fly at various altitudes, from below 190 to about 350 miles above sea level, depending on the mission requirements. Spacecraft or other payloads that must operate at higher altitudes have rocket motors attached. These are fired after the spacecraft is a safe distance away from the orbiter. Many communications satellites reach a final altitude of about 22,300 miles where they operate above the equator. The Magellan, Galileo, and Ulysses spacecrafts had extra stages attached that fired to send them on their way to other planets.

How hot or cold does it get in space? In space around the Earth, including the vicinity of the Moon, objects in direct sunlight can heat up to temperatures of about 250 F (121 C). When shielded from the sun, objects can cool to around -250 F (-156 C). Astronauts in spacesuits, or in the orbiter cabin, work in a steady temperature range of 70-80 F (21-27 C), as long as the thermal control systems are working properly. How do the astronauts dress while on a space shuttle mission? Early life-support systems were cumbersome, and the astronaut's ability to move in them somewhat restricted. The Shuttle spacesuit is far less bulky and much more comfortable. Shuttle spacesuits come in standard pieces in several sizes, which can be combined to fit either male or female crew members. These pieces can be repaired and reused over a number of years, making it much less expensive to outfit an astronaut today than in the past. While in the shuttle's crew compartment, astronauts wear light-weight clothing as if they were in a mild climate on Earth.