Laser Launch into Orbit

Electric propulsion using high power laser beaming makes way more sense outside the atmosphere for non-launch use cases, where thrust requirements to achieve desired delta-V usually aren't measured in kN and the mission longevity implied by higher Isp matters so much more and there isn't a pesky atmosphere in the way of power beaming or any concern about accidentally ablating airliners.

Numerous startups are tackling the power beaming issue with relatively short timelines and in some cases a lot of funding, but the scale of what's actually been publicly demonstrated with lasers is unimpressive...

Yeah, seems like chemical rockets, or a railgun or trebuchet or something to get it up to speed first would be a lot more efficient than ground to orbit with just a laser.

Yes, but supposedly a laser needs a medium like air to stay coherent. So a weakly powered laser has shorter range in space than (clear) air.

Can you expand on this? I thought that without the usual effects in a medium that's filled with particles lasers achieve much greater ranges.

This is incorrect, but please expand on this because I want to understand the misunderstanding.

Other way round: atmosphere diffracts light away.

You have that in reverse. Atmosphere distorts a laser beam. You need to pump a ton of power to have a stable self focusing beam in atmosphere.

And isn't this focusing itself unstable, leading to filamentation?

It's really hard to beat chemical rockets for launch.

It's not generally understood just how remarkable rocket engines are. They're the most efficient heat engines we can make. They are orders of magnitude better than other heat engines in power/mass and power/$. Their Isp is fine for launch, particularly for the first stage where most of the propellant is consumed.

>Electric propulsion using high power laser beaming makes way more sense outside the atmosphere for non-launch use cases

"Roundtrip Interstellar Travel Using Laser-Pushed Lightsails"

https://ia800108.us.archive.org/view_archive.php?archive=/24...