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Electric propulsion using high power laser beaming makes way more sense outside the atmosphere for non-launch use cases, where thrust requirements to achieve de
by notahacker 2y ago
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...
- khafra 2y agoYeah, 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.
- pfdietz 2y agoIt'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.
- a3w 2y agoYes, 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.
- Tade0 2y agoCan you expand on this? I thought that without the usual effects in a medium that's filled with particles lasers achieve much greater ranges.
- eternauta3k 2y agoThis is incorrect, but please expand on this because I want to understand the misunderstanding.
- pjc50 2y agoOther way round: atmosphere diffracts light away.
- lightedman 2y agoYou 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.
- pfdietz 2y agoAnd isn't this focusing itself unstable, leading to filamentation?
- floxy 2y ago>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/items/wikipedia-scholarly-sources-corpus/10.2514.zip&file=10.2514%252F3.8632.pdf https://ia800108.us.archive.org/view_archive.php?archive=/24...