RAS question
What is the key difference between GSLV Mk-II and GSLV Mk-III (LVM3)?
Correct answer: (C) GSLV Mk-III has an indigenous cryogenic upper stage (C25) with higher payload capacity.
GSLV Mk-III, now called LVM3, differs from GSLV Mk-II mainly by using the more powerful indigenous C25 cryogenic upper stage and carrying a higher GTO payload of up to 4,000 kg.
Explanation
The key difference is payload class, driven by the cryogenic upper stage. GSLV Mk-II uses the CUS cryogenic upper stage for about 2,500 kg to GTO, while GSLV Mk-III, now LVM3, uses the indigenous C25 cryogenic upper stage and can place up to 4,000 kg in GTO. ISRO's launcher page supports this comparison at the vehicle level: it says GSLV with an indigenous cryogenic upper stage enabled launches of up to 2-tonne class communication satellites, while LVM3 is a next-generation launch vehicle for 4-tonne class communication satellites and was developed with indigenised technologies including the C25 cryo stage. GSLV Mk-III/LVM3 therefore represents the real technical and capacity jump.
Why the other options are wrong
- (A) LVM3 can launch 4-tonne class communication satellites and heavier payload classes, so reducing it to only polar-orbit missions misstates its role.
- (B) GSLV Mk-III uses two S200 solid strap-on boosters, so assigning the strap-on configuration only to another vehicle reverses the vehicle configuration.
- (D) GSLV Mk-III is not a solid-only launcher; ISRO's description includes solid, liquid and cryogenic elements, including the C25 cryogenic stage.
Concept
Launch-vehicle technology under Science and Technology includes cryogenic stages, payload class and mission capability. RAS repeats such comparisons because ISRO launchers are a standard way to ask applied space-technology questions without requiring mission-specific memorisation.