Vocabulary Builder — Essay & Answer Writing
Specific Impulse
A measure of rocket engine efficiency, the thrust produced per unit weight flow of propellant consumed per second; higher specific impulse means more payload can be carried with less fuel.
Latin specificus (particular) + impulsus (a push), technical aeronautical engineering term
"ISRO's CE20 cryogenic engine achieves approximately 440 seconds of specific impulse in vacuum, the highest of any chemical propellant pair, which is why cryogenic engines are essential for placing heavy satellites in geostationary orbit."
Frequently tested in UPSC Prelims Science & Technology questions on space. The key fact: cryogenic engines have the highest specific impulse (~440 seconds) among chemical propulsion systems; solid fuel has ~250 seconds; liquid storable propellants ~300 seconds. This is why India's Gaganyaan mission uses the CE20 cryogenic engine on LVM3. Also important for understanding why the US denied cryogenic technology to India in 1994, MTCR concerns about dual-use for ballistic missiles.
