How does it feel to launch into space on a rocket? : NPR

What does it take to launch into space?

The answer is other than money, hard work and lots of moving parts Science! This summer, NPR’s science podcast is launching Short Wave Space Camp, a series about all things weird and wonderful in our universe. We’ll start with how to get into space.

Rockets and Isaac Newton

It goes without saying for the most part, but to get to space one has to be in some sort of spacecraft attached to a rocket.

That rocket will shoot exhaust when it leaves the launch pad. That exhaust shoots toward the launch pad. This is where Isaac Newton’s third law of motion applies. This law states that “for every action there is an equal and opposite reaction”. So when the exhaust pushes down, it creates an upward force and sends the rocket skyward.

A good example on a smaller scale is a common physics demonstration of someone holding a fire extinguisher and sitting on something with wheels. Like in this video, when the fire extinguisher fires, the person walks in the opposite direction.

The exhaust from a rocket launching into space does the same thing.

The rocket has to go really fast because it needs to overcome the curvature of space-time itself. The fabric of our universe, called space-time, can be thought of as a bendable plate. The mass of the Earth creates a flat structure of space-time curving inwards in a funnel shape. Moving up the funnel—and thereby escaping Earth’s gravity—is more difficult than moving down.

G-forces and why floating falls

When these rockets launch, astronauts experience intense g-forces.

G-forces come from when your body experiences acceleration. If you’re just sitting or walking around on Earth, you probably won’t notice them – even though there’s always regular Earth gravity, which is 1 G.

You’re more likely to notice them when you’re doing something like riding an elevator quite quickly. Then you feel heavier.

But the difficulty of being in a fast elevator is nothing compared to what astronauts experience during launch. Retired Navy Captain and former NASA astronaut Wendy Lawrence recalled the feeling of intense g-forces to NPR in a recent interview.

“I remember on my first flight I thought, ‘Oh my God, someone just sat on my chest,'” she says. “I was trying to see if I could reach out in front of me … and I thought, ‘Wow, I can’t hold it there against this tremendous force and acceleration that this amazing space vehicle is producing.’

This experience is changing quite quickly. Once the rockets detach from the spacecraft, the force pushing the astronauts into their seats is gone. They begin to float under the seat belts.

He feels what is commonly called weightlessness.

But the gravity didn’t go away. Even on the International Space Station, astronauts experience microgravity.

You can get a small taste of this feeling on Earth. There are amusement park rides that shoot up—make riders feel heavy—and then drop the rider. During this fall, riders feel weightless, even though they are actually falling. In physics, this is called free fall. All astronauts on the International Space Station are technically falling very slowly and therefore feel weightless.

Captain Lawrence says it’s an amazing experience. “Just relax,” she recalls. “You’re suspended right there in mid-air and you want to park yourself in front of the window and float in front of it and watch the world go by.”

To get into orbit is to fall and miss the Earth

It turns out that the orbit, as the astronauts aboard the International Space Station do, is descending. Specifically, it’s towards Earth.

Newton had a series of thought experiments to explain this idea.

Scenario 1: Imagine that you are standing on flat ground. Now imagine that you shoot a cannonball horizontally from your place on the ground. In this scenario, the cannonball will travel horizontally for a while before it begins to fall down a curved path. This is projectile motion.

Scenario 2: You shoot this same cannonball horizontally – from the top of a very tall mountain. In this case, the ball would hit the ground even further because it should hit further and be in the air longer. If you shoot the cannonball at a higher speed, it will travel even further. The curved road is getting longer and longer.

Scenario 3: With a high enough launch velocity, you can make the cannonball fall in a curved path that matches the curvature of the Earth. Because the curvatures coincide, the cannonball still misses the Earth. That’s what it means to have something in orbit. The cannonball falls but never reaches the ground.

Next week’s shortwave space camp preview: Pluto

If we now go from Earth’s orbit to the end of our solar system, we will pass by the once beloved planet Pluto. Next week we ask: Why are there only 8 planets in our solar system? What does it mean that Pluto was demoted to a dwarf planet all those years ago? We also explain why Pluto’s geology surprised scientists.

Have other space stories you want us to cover? Write to us at the address shortwave@npr.org.

Listen to shortwave on Spotify, Apple Podcasts and Google Podcasts.

Listen to every episode of Short Wave without sponsors and support our work at NPR by subscribing to Short Wave+ at plus.npr.org/shortwave.

This episode was produced by Berly McCoy, edited by Rebecca Ramirez, and fact-checked by Regina Barber, Emily Kwong, and Rebecca. Gilly Moon was the sound engineer.