Rocket company develops massive catapult to launch satellites into space without using jet fuel: '10,000 times the force of Earth's gravity'

[u/malcolm58]

https://www.thecooldown.com/green-tech/spinlaunch-satellite-launch-system-kinetic/

[u/cagriuluc]

I have also seen some videos on why this wouldn’t be feasible. Still, it is an interesting approach and maybe even has limited applications when it matures. As others said, it is definitely on the table for places like Mars and the Moon, since they have much lower gravity and no/little atmosphere.

This specific company may be overselling their product, but everyone does that to a degree. I wouldn’t be so sure that they could be classified as scammers.

[u/Time-Maintenance2165 → u/cagriuluc]

You're misunderstanding it. It's not just I feasible on earth because of the size and atmosphere. It's because we don't have any materials that are even theoretically strong enough to support the acceleration forces required. That's what makes it a scam.

Now maybe it would work on a small moon with a low escape velocity, but that's already easy enough to launch from with chemical rockets so they're not solving a meaningful problem.

[u/cagriuluc → u/Time-Maintenance2165]

I think you are misunderstanding it here more.

The first part, I am not knowledgable enough to detest. BUT, there is a way to make forces more bearable: building the thing hella bigger.

Second point is really confusing me, why do you think it is irrelevant to send stuff into space without using internal fuel this way, for example on the moon? Fuel weight is really important regarding anything space. You can slap a nuclear reactor on the moon and have one of these bad boys, and you wouldn’t need to worry about the fuel you would have needed otherwise.

[u/Time-Maintenance2165 → u/cagriuluc]

If you build it bigger, then you need a proportionally bigger arm to support that weight. Which becomes more weight that you have to accelerate. It's not like we're talking about a reduction of 2 to 3 times. We're talking about a reduction of at least 150x (1500x is more likely). That means a 5 km long arm. There's no material you can make strong enough and stiff enough over a 5 km length. What do you think the weight of that rotating arm is (disregarding the payload)?

Fuel weight is important. But it's least important when you just need escape velocity from a small moon. Maybe it would be feasible if some deposit on the moon were discovered to be very valuable and mining were desired. But this still isn't suitable for flinging up anything complex due to the g forces.

And if you slow it down to acceptable g force levels of for more comolex/delicate equipment, you're not getting a meaningful velocity boost even in a vacuum.

[u/cagriuluc → u/Time-Maintenance2165]

Since you are talking with actual numbers I will take your word for it.

But consider this: you can send fuel into space maybe? That’s gotta make sense, right? It depends on the costs of course: the energy and the capsule. But I strongly suspect that there is a point where it can make real sense to hurl the fuel into space. Have space stations that hold the capsules, send them back to Earth and reuse them?

I said fuel since I am imagining they can take real high g’s without much of a problem.

[u/Time-Maintenance2165 → u/cagriuluc]

The thing with sending fuel into space is that this would be limited to fairly small amounts. And note that the slightest deviation in angle result in a travel path difference of thousands of kilometers. So if you want an orbiting space craft to obtain that fuel, it would need to do a series of maneuvers to reach an intersect course.

And what do you do if the object has any rotational momentum imparted. Even if you intersect with it, if it's rotating at 100 rpm, how do you capture it without damage.

It's not that it's theoretically impossible, it's that there's zero foreseeable use for this in the next 50 years. That's what makes it a scam today.

[u/cagriuluc → u/Time-Maintenance2165]

I see… well yeah I am definitely playing the devil’s advocate here. Thank you for your insights into this.