Hurling Satellites Into Space

Copper · 1 Feb 2021, 23:02

https://www.wired.com/story/hurling-satellites-into-space/?utm_medium=social&utm_social-type=owned&mbid=social_facebook&utm_brand=wired&utm_source=facebook&fbclid=IwAR1ND8n8YIz3t2Yq2Y-DAARvVZ7iMq83GKUWIPrUb9p9p6Kb8ZrDF3-a7tg

Hurling Satellites Into Space Seems Crazy—but Might Just Work

A startup called SpinLaunch wants to do away with costly launch rockets. Let's look at the physics.

IT’S OBVIOUS, BUT I'll say it: Rockets are cool. Sending stuff into space with a chemical reaction is just stupid-awesome. But clearly, we can't keep using chemical rockets to put satellites in orbit. They're too expensive, and the fuel is heavy—which means you need even more fuel to carry the fuel.

So I’m excited about this new proposed launch system, the SpinLaunch. The basic idea is to physically throw a missile off the planet, in much the same way our ancestors hurled rocks with a leather sling. In this case, a giant centrifuge would spin the craft around in a vacuum to build up insane speed, then open a door and release it into the sky.

But the physicist in me also can’t help being a little skeptical. The challenges here—like air drag, for starters—seem enormous. I’m not saying this thing won’t work, but I want to crunch the numbers myself to see what’s involved. Come on, let's take it for a spin!

Acceleration Sensation

Before I get to the calculations, let's look at the details of the system and the physics involved. Here's what I know about SpinLaunch from current specs:

Launcher spins in a circle with a diameter of 100 meters.

Payload mass of 100 kilograms, plus maybe another 100 kg for the spacecraft (I assume this is just a small prototype)

Rotation speed at launch of 450 revolutions per minute

Launch speed of 7,500 kilometers per hour (4,660 mph)

Spin-up time of 1.5 hours

Launch angle at 35 degrees