Microgravity

Tim Peake Mascot Illustration

Microgravity is an environment that can only be consistently experienced in orbit. This activity introduces some of the effects of microgravity and discusses why microgravity science is so important.

What is microgravity?

Whenever we think of astronauts in space, we picture them floating around as if the Earth is exerting no gravitational force. This is of course not the case. Gravity on the International Space Station is still around 90% as strong as it is on the surface of the planet. So what is going on?

We can temporarily experience microgravity on the Earth with a parabollic flight. If an aeroplane begins to climb, and then throttles back its engines so as to only provide enough thrust to counteract air resistance, then it effectively becomes a projectile: the only overall force acting on it is gravity pulling the aeroplane towards the surface of the Earth.

Gravity affects all particles equally. A small mass and a large mass dropped in a vacuum will fall toward the Earth with the same acceleration, and hit the ground at the same time (as spectacularly shown on the Moon during the Apollo 15 mission). You can demonstrate this with two identical sized balls of equal diameter, and therefore equal air resistance, but different mass.

Our aeroplane is being accelerated towards the ground with the same acceleration as anything inside it. If you are in the plane, the floor is falling away from you as fast as you are falling towards it. Lift up your legs and you will float with respect to the plane. That is, until the plane pulls out of this curve, making you temporarily feel twice as heavy as it rapidly climbs.

An object in orbit is also falling towards the Earth, as is anything inside. It just has enough sideways speed that the curve of its path matches the curve of the Earth and so it never hits the surface. This is what causes microgravity.

What do we research?

While there is no doubt that microgravity is an extremely fun (if often queasy) experience for humans, there is a lot of unique science that can be done in orbit. Without the influence of gravity, crystals will grow larger, more uniformly and with fewer imperfections than on the Earth. The most accurate clocks (with the exception of atomic clocks) on the Earth use precision quartz crystals and the more perfect the crystal, the more accurate the timing. Current research into Microgravity A unique environment producing unique science protein crystals may even potentially lead to more effective, targeted cancer treatments. Microgravity research is a relatively young, but exciting field. With cheaper, more regular access to orbit, researchers will have the chance to test far more ideas.