Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

|Fewer Letters|More Letters| |-------|---------|---| |DARPA|(Defense) Advanced Research Projects Agency, DoD| |DoD|US Department of Defense| |FFSC|Full-Flow Staged Combustion| |H2|Molecular hydrogen| | |Second half of the year/month| |HEU|Highly-Enriched Uranium, fissile material with a high percentage of U-235 ("boom stuff")| |Isp|Specific impulse (as explained by Scott Manley on YouTube)| | |Internet Service Provider| |LH2|Liquid Hydrogen| |NTR|Nuclear Thermal Rocket| |SSTO|Single Stage to Orbit| | |Supersynchronous Transfer Orbit|

|Jargon|Definition| |-------|---------|---| |EMdrive|Prototype-stage reactionless propulsion drive, using an asymmetrical resonant chamber and microwaves| |hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer| |turbopump|High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust|

^(11 acronyms in this thread; )^(the most compressed thread commented on today)^( has 15 acronyms.)
^([Thread #8497 for this sub, first seen 30th Jan 2023, 16:09]) ^[FAQ] ^([Full list]) ^[Contact] ^([Source code])