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Well, I'm quite ignorant about space exploration in general, but I hope I don't make too many misconceptions.

So, from what I could find on the internet, there is a certain type of spacecraft propulsion called "solar sails" that it simply is a reflective film that is pushed by solar light. Therefore, you could push things using only lasers, and in fact, there is a project that aims to launch micro-satellites the size of a coin into Alpha Centauri, called "Breakthrough Starshot" that uses this same idea. But I doubt it would be possible to launch things from here to orbit using lasers in a practical and efficient way.

Well taking this into consideration, and the fact that it costs thousands of dollars per kilogram of payload to simply launch into orbit, it makes me wonder if there is any way of launching reeeeally small objects into space using as little energy as possible.

For example, even though the current record of smallest satellite launched into space (Kicksat) was launched in big numbers inside a bigger container.

And I could think that launching a coin of material every hour (or minute) to the International Space Station in order to build bigger stations would be the most efficient way, but I think that maybe launching a bullet in the direction of a space station is not the safest way of launching material to space.

There are any kind of projects and/or researchs in this field?

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    $\begingroup$ I can’t tell exactly what this is asking, the title and body seem completely different, and the final sentence is yet further out. $\endgroup$
    – Topcode
    Dec 16, 2021 at 0:26
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    $\begingroup$ This is an interesting question! For conventional rockets there does seem to be a lower limit; sounding rockets have managed to put single cubesats into orbit but it's probably more cost effective to put a bunch of them in a bigger one (If there "won't be" rockets to launch individual cubesats, then why did JAXA build exactly that? (SS-520-xx)) Though your question is not necessarily limited to conventional rockets it does specify "our current technology" and "into space" but not necessarily orbit $\endgroup$
    – uhoh
    Dec 16, 2021 at 5:49
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    $\begingroup$ @CuteKItty_pleaseStopBArking it's right there, just a little further along within the same sentence. Goodness! $\endgroup$
    – uhoh
    Dec 16, 2021 at 12:03
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    $\begingroup$ Joke answer: A nuclear bomb and a manhole cover: businessinsider.com/… (but it almost certainly evaporated before it got there) $\endgroup$
    – eps
    Dec 16, 2021 at 16:40
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    $\begingroup$ More seriously, the thrust of this question seems to be about cost and in that it makes a fundamental error in assuming that smaller is better (cheaper). Just the opposite, economies of scale and the physics involved means you want to go bigger, like with starship. There's no plausible way to do your idea of shooting small things to the ISS (basically a railgun type idea) because of the manhole problem - there's no known away to make it survive the forces of launch and atmosphere drag. you'd also need to circularize the orbit or devise a catching mechanism. $\endgroup$
    – eps
    Dec 16, 2021 at 17:02

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The atmosphere makes it harder. On a per-kilogram basis, it is much more efficient to accelerate massive objects through the atmosphere than light ones. That's because the mass of the spacecraft is big compared to the mass of the air it pushes out of the way.

So consider launching from the moon. People have proposed using a magnetic accelerator to shoot bulk materials from the moon into orbit. And I don't think there is really a lower limit on the payload mass. But, the thing is, the energy it takes to accelerate the payload is proportional to the mass. So 1000 one-gram payloads takes the same energy as a single 1-Kg payload. And, if you're going to build all that infrastructure, it's more efficient to send larger loads at once.

The thing about the Starshot project is that getting something to even 10% of the speed of light is really pushing the bounds of what we can imagine doing with predictable technology. The space probe can't carry the rocket fuel with it because the fuel itself adds mass, so you have to add more fuel, but that adds more mass, and so on. If the fuel is efficient enough this does finally stop (rockets do work), but the numbers don't work out well for an interstellar probe. This is known as the "tyranny of the rocket equation."

So instead you make them tiny and provide the acceleration from a fixed source of power.

But the tradeoffs for getting to orbit are just different.

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