Engineering Meteoroid Shields

In this lesson, students apply what they know about forces and motion to design a technology that solves the problem of collisions between meteoroids and spacecraft.

• Rockets are technologies that apply Newton’s three laws of motion to get into space.
• Space debris is a serious problem facing objects in space, including the International Space Station, satellites, and spacecraft, because space debris is moving at high speeds and can damage spacecraft.
• Moving objects have kinetic energy, and whenever two objects come into contact with one another, they exert a force on each other for a short period of time. This is called a collision, and it causes energy to transfer between objects.
• Engineers bring together everything they know about forces and motion to design technologies that can protect objects in space from damaging collisions.

• How do rockets use action-reaction forces (Newton’s third law) to move?
• How does the mass of the rocket affect its acceleration (Newton’s second law)?
• What forces act on a moving rocket once it is in motion within Earth’s atmosphere?
• Why is space debris such a concern for spacecraft and satellites?
• Why would a more massive piece of space debris cause more damage than a less massive object?
• Why would engineers who want to solve the problem of collisions with space debris need to know about momentum?
• What are the key scientific principles that engineers need to know to solve this problem?
• Why is a parachute a good example of a technology that solves the problem of momentum during a collision?

Misconception: A continued force is required to keep an object moving. 

Fact: According to Newton’s first law, an object in motion will continue moving until acted on by an outside force. It does not need a continued force to keep it moving.

Misconception: Gravity only exists on Earth.

Fact: All matter, both on Earth and in space, has gravity. The sun has the strongest gravity in our solar system, which is why planets orbit it.

Solar system : a collection of planets and other objects that orbit a sun

Engineer : a person who uses scientific knowledge and mathematics to solve problems by creating new technologies

Momentum : the measurement of an object’s mass multiplied by its speed

Prototype : a scaled-down first draft of a technology

Building the International Space Station

The International Space Station is slightly larger than an American football field. It is so large that it had to be built in space. The first piece was launched in 1998, and it wasn’t finished until 2011. However, people began living on it in 2000.

The space station had to be built piece-by-piece in space because there is no rocket powerful enough to launch the entire station into space at one time. The completed space station has a mass of almost 453,592 kilograms (1 million pounds). Scientists and engineers had to send the separate parts of the space station on rockets. It took more than 40 missions to get all of the materials into space and assembled.

Engineers who designed the rockets that launched the parts of the space station into space applied Newton’s three laws of motion:

1. Stationary objects won’t start moving, and moving objects won't stop moving unless the forces pushing or pulling on these objects become unbalanced (the law of inertia).

2. Force = mass times acceleration.

3. For every action, there is an equal and opposite reaction.

Rockets are designed to move because of action-reaction forces. The rocket pushes combustion exhaust downward—the action. This is also called thrust. In reaction, the exhaust pushes the rocket upward.

Because of Newton’s second law, the greater the thrust, the more the rocket will accelerate upwards. Similarly, the more massive the rocket is, the more powerful the thrust will need to be. This is why the International Space Station couldn’t be launched after it was already built. There is no rocket that can produce a powerful enough thrust to get an object that massive into space.

Once the rocket begins to move, it will continue to move until another force acts on it to slow it down or stop it. On Earth, gravity pulls down on the rocket. The rocket also experiences drag as it moves through the air. Remember that drag is a force that transfers motion out of an energy system by causing some of the energy of a moving object to change into heat. Drag acts on an object in the opposite direction as the movement.

Because of this, the rocket must produce enough thrust to counter Earth’s gravity and the air’s drag. The amount of thrust needed depends on the rocket’s mission. If it is to explore Mars, for example, the rocket needs enough thrust to move beyond Earth’s gravitational field entirely. However, rockets heading to the International Space Station need enough thrust to move into space, but not so much that they leave Earth’s gravitational field. With the right amount of force, the rocket can begin to orbit Earth. If the rocket did clear Earth’s gravitational field, it would continue to move in a straight line because of inertia.

Once rockets carrying spacecraft are successfully launched into space, astronauts must be very aware of space debris. More than 500,000 pieces of space debris orbit Earth. Some of the debris is natural, such as meteoroids. However, the most common space debris orbiting Earth comes from human- made sources, including old spacecraft that are no longer in use. These objects travel at speeds up to 28,163 kilometers per hour (17,500 mph).

At those speeds, even tiny paint flecks can damage structures because moving objects have kinetic energy. Whenever two objects come into contact with one another, they exert a force on each other for a short period of time. This is called a collision.

The force of a collision causes energy to transfer from one object to another. The faster an object is moving, the more energy it will transfer. When a moving object hits another object, the force of the collision transfers some of the kinetic energy into the second object, and into other forms of energy, such as sound. This is why collisions often make loud noises. The force can also transfer energy that changes the objects’ motion.

For the interactive activity of this lesson, students apply Newton’s third law of motion to design a shield technology for an orbiter to prevent damage from the phenomena of meteoroid collisions in space. First, students consider the criteria and constraints of the problem before they design and build their prototype shield. Then, they test the prototype to analyze how effective it was before they make any needed modifications to their design.