SSC CGL 2025 Tier-I · 16 September 2025, Shift 2 · General Awareness · Question 13 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

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SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Fill in the Blanks: NISAR maps the global surface every ______.

(a)3 days
(b)12 days
(c)24 hrs
(d)5 days

Answer

Why

Correct — B. NASA describes NISAR as giving complete global coverage every 12 days.

Its orbit repeats over the same ground on a 12-day cycle, so nearly all of Earth's land and ice is imaged again at a fixed interval. That regular revisit is what lets it measure slow ground movement.

Why the others are wrong

(a)
3 days — 3 days is not NISAR's figure. NASA gives complete global coverage every 12 days, built up from a radar swath more than 240 km wide.
(c)
24 hrs — 24 hours is far too short for one radar satellite to image the whole globe. NISAR builds its global coverage over a 12-day repeat cycle.
(d)
5 days — 5 days does not match NISAR's published cycle. NASA's figure for complete global coverage is 12 days.

Concept

NISAR (NASA-ISRO Synthetic Aperture Radar) is a joint Earth-observation satellite. It carries NASA's L-band radar (24 cm wavelength) and ISRO's S-band radar (9.4 cm), with a 12 m reflector antenna.

It was launched on 30 July 2025 from Sriharikota on ISRO's GSLV-F16, into a sun-synchronous dawn-dusk orbit. Radar sees through cloud and works at night, so a regular 12-day revisit holds whatever the weather.

Key facts

NISAR provides complete global coverage every 12 days.
NASA supplied the L-band radar (24 cm) and ISRO the S-band radar (9.4 cm).
NISAR was launched on 30 July 2025 aboard GSLV-F16 from Sriharikota.
It flies in a sun-synchronous dawn-dusk orbit at about 747 km.

Study next

Synthetic aperture radar and what L-band and S-band each seeSun-synchronous, polar and geostationary orbitsISRO's GSLV launches

Common traps

Choosing 24 hours because a low-orbit satellite circles Earth many times a day, when orbits are not global coverage.
Confusing the 12-day repeat cycle with the orbital period, when NISAR completes 173 orbits in each cycle.

The mission also appears at Tier-II, 19 Jan 2026, 11:00, GA Q.10, which asks for its correct description: a joint ISRO–NASA mission using L- and S-band radar.

Related PYQs

No directly related past PYQ was found.

Topic: Scientific Research — all 220 SSC CGL questions on it, every solved shift.