In the context of recent developments in space technology and earth observation missions, … — State PSC Exam

In the context of recent developments in space technology and earth observation missions, evaluate the given statements regarding the NASA-ISRO Synthetic Aperture Radar (NISAR) project:

I. NISAR utilizes a dual-frequency radar system comprising an L-band synthetic aperture radar supplied by NASA and an S-band synthetic aperture radar supplied by ISRO.
II. The mission employs the SweepSAR technique to achieve simultaneous high spatial resolution and wide swath coverage across terrestrial and ice surfaces.
III. The spacecraft operates from a Geostationary Equatorial Orbit (GEO) at an altitude of approximately $35,786\text{ km}$ to ensure continuous monitoring of a fixed geographic region.

Which of the statements given above are correct?

I and II onlyCevap
B
II and III only
C
I and III only
D
I, II, and III

Cevap

Statements I and II are correct, whereas Statement III is incorrect. Thus, the correct choice is 'I and II only'.

The NISAR mission features an L-band SAR developed by NASA and an S-band SAR developed by ISRO, operating together to collect polarimetric and interferometric data. Using SweepSAR architecture, NISAR achieves both wide-swath coverage (~

240\text{ km}

) and high resolution. It operates in a polar Sun-synchronous Low Earth Orbit at ~

747\text{ km}

altitude, allowing it to image the entire globe every 12 days. Statement III falsely claims the orbit is geostationary.

Adım Adım Çözüm

Evaluate Statement I regarding agency payload contributions.

Statement I is correct. NASA provides the

24\text{ cm}

wavelength L-band Synthetic Aperture Radar (SAR), while ISRO provides the

12\text{ cm}

wavelength S-band SAR.

To verify technical hardware allocation between NASA and ISRO.

Assess Statement II regarding sensor architecture and SweepSAR functionality.

Statement II is correct. SweepSAR technology allows the radar receiver to sweep across an expansive swath of over

240\text{ km}

while preserving high spatial resolution.

To confirm how the satellite overcomes traditional resolution-versus-swath width trade-offs.

Analyze Statement III regarding orbital parameters.

Statement III is incorrect. NISAR is launched into a polar Sun-synchronous Low Earth Orbit (LEO) at an altitude of roughly

747\text{ km}

with an inclination of

98.4^\circ

. Geostationary orbit (GEO) cannot provide polar coverage or repeat-pass interferometry for global ice-sheet dynamics.

To check orbital mechanics against Earth observation operational requirements.

Anahtar Kavram

Dual-frequency SAR instruments, SweepSAR imaging, and Earth observation orbital parameters

Tahmini Süre:2m 0s

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