Excerpt from new book


If you are weightless in space, would you be able to pick up heavy objects?


Objects in space may be weightless, but they still have mass. And it requires a force to move that mass. Newton’s Second Law of Motion is the relationship between mass, force, and acceleration. F = ma. F is force, m is mass, and the letter a stands for acceleration. This law applies on Earth and in space.

Objects on the former Space Shuttle, and now on the International Space Station, may weigh hundreds of pounds. You could easily hold that mass in your hand. But if you want to move it, you must apply a force. A force is simply a push or a pull.

Once you get it moving, say from the floor to the ceiling, it will continue to move “up” until you apply a force to stop it. If you don’t apply a force to stop it, the object will hit the ceiling.

Astronauts use a foot restraint system. Canvas loops are taped to the floor and astronauts slide their feet into the loops. When the astronauts are space walking outside their craft, their boots have a lip on the back of the shoe that locks into foot restraints. Foot restraints are placed on the floor, doors, and ceilings.

The foot restraints allow the astronaut to apply some leverage to whatever they are trying to move, lift, or manipulate. The restraints anchor the astronaut in place. They substitute for the weight that you and I have, that gives us anchorage here on Earth.

The term weightlessness is somewhat misleading and implies that there is no gravity in space. In fact, the pull of gravity in Earth orbit is almost identical to the force of gravity on the surface of the Earth. The previous Shuttle and now the International Space Station and the astronauts inside are actually in a state of free fall.

Let’s say you stand on a bathroom scale and jump off a building. On the way down, you read the scale. You are weightless and in free fall, and the scale reads zero. Space is the same way. When in Earth orbit, the spacecraft and astronaut are moving forward and falling downward at the same time. The fall of the International Space Station and the astronauts inside matches the curvature of the Earth.


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