Giant catapult sends satellites into space

There's some pretty fundamental problems with spin launch.

Atmospheric drag is greatest at sea level, and drops as altitude increases. A traditional lift vehicle is traveling slowest during the early parts of its ascent, and starts reaching high velocity once it's cleared the thicker parts of the atmosphere. In contrast, spin launch is at its highest velocity (before the rocket engine ignites) right after it's released, so it's going to bleed off a lot of speed before it reaches the upper atmosphere.

Second, spinning exerts very heavy lateral Gs on the vehicle and load. This is not typical for space launch payloads, which are usually only designed to withstand vertical Gs. When the catapult releases the payload, atmospheric drag is going to put heavy vertical Gs on the payload. So a payload delivered through spin launch is going to have to withstand both lateral and vertical Gs.

Its an interesting concept, but I'm not sure if the advantages of this approach outweigh the disadvantages.

I do see a future use case for spin launchers based in vacuum, say, on the moon. Or maybe on Mars where atmosphere is much thinner.

From what I can tell looking at SpinLaunch's website and web search, they were founded in 2014, "launched" a couple projectiles in atmosphere, had a leadership change in 2022, and have been pretty quiet since then.

Unless I've missed something, the headline "Giant catapult sends satellites into space" is not true. The company appears to be on life support.

https://thespacebucket.com/what-happened-to-spinlaunch-its-p...

Accelerating in a huge vacuum chamber seems pretty difficult to achieve, and wouldn't there be a huge shock to the vehicle as it hits a wall of dense air?

How much of a difference would a low pressure chamber make, I wonder? Maybe you could build the circular accelerator then a much longer exit pipe that runs up the side of a mountain. Although that sounds way, way easier said than done! But if your exit air pressure is roughly equal to your accelerator air pressure, then you don't need a fancy airlock system.

The tether they proposed also seems a bit too much of the wishful thinking like "we just need a bundle of carbon nanotubes 1km long!" Wouldn't an electromagnetic accelerator work better?

Orbital accelerators are cool, IMO they feel much more sci-fi than rockets (and still a step below space elevators). They're not without their tradeoffs, though: the G-forces involved mean they're not suitable for living creatures, and because of atmospheric drag they're most suited to putting things into lower orbits.

https://en.wikipedia.org/wiki/Space_gun

"In Project HARP, a 1960s joint United States and Canada defence project, a U.S. Navy 410 mm (16 in) 100 caliber gun was used to fire a 180 kg (400 lb) projectile at 3,600 m/s (12,960 km/h; 8,050 mph), reaching an apogee of 180 km (110 mi), hence performing a suborbital spaceflight."

I remember this being a horrible idea for many reasons.

One reason being the speed needed at the start which probably meant most loads burning up in the thick atmosphere immediately.

Another reason being that if you would use it to start a rocket which will only use the spin launch as a booster replacement, you would run into the problem of the fuel being pressed towards the front of the rocket as it is constantly decelerating after the launch. So you would probably need a system to actively move the fuel down to the nozzle.

Metaculus has this at 4% that it will launch anything to low earth orbit by 2032.

https://www.metaculus.com/questions/12245/spinlaunch-payload...

According to The Space Bucket youtube channel, there has been no update to the company's progress since 2022, and there was a shake up in the top leadership. It looks like this project is likely dead in the water.

https://youtu.be/kGxmCvLb9bs

Guess we’re gonna have to build our next generation of spacecraft with an inch of milled solid titanium, just like we build our deep sea submarines

Somehow it’s hard to believe that the lower dense part of the atmosphere doesn’t slow it down or even burn it. It happens when these things fall down… why not when going up?

I have so many questions..! (And maybe the answers are somewhere on the page, but its navigational paradigm is too atrocious for me to handle)

- how fast do you have to push something through the atmosphere to have it reach space?

- and, how fast is the lever spinning to reach that velocity? how precise do you have to time the release?

- after release, your lever is going to be pretty unbalanced. having seen what happens to an unbalanced ultracentrifuge in a lab (spinning a few grams of biological samples), how does this thing launch a 100kg satellite without wrecking the launch station?

- does this mean all the remaining angular momentum is in an opposite weight you discard simultaneously by slamming it into the ground? do you just sling the payload around in some ridiculously unbalanced manner?

- can you launch things with liquids (eg., fuel) at all due to crazy sloshing mechanics?

I could imagine commercials, in movies they have this bow and arrow guy the arrow shoots towards the viewer then the logo appears

Here it's a baseball pitcher or that spinning throw (not discuss, they use a ball) then it says "Spin Launch"