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The joint NASA/ISRO (Indian Space Research Organization) Synthetic Aperture Radar (NISAR) platform will create global maps to provide a better understanding of changes in Earth’s ecosystems, ice mass, vegetation biomass, sea level rise, ground water, and natural hazards.

Learn more about NISAR

Type

Earth Observation Satellite

Objective

Global measurements of the causes and consequences of land surface changes.
Indian Space Research Organization (ISRO)
NASA and the Indian Space Research Organization (ISRO) each provide SAR instruments , at two different radar frequencies, to measure changes on Earth's surface in unprecedented detail.
Learn more about NASA's partnership with ISRO
The logo for the Indian Space Research Organization (ISRO) in blue and orange

The NISAR Science Data System (SDS) team will generate the L-Band Level 0, Level 1, and Level 2 products; the NISAR Project Science and Science Teams will generate the Level 3 products.

ProductProduct Description
L0B RRSDLevel 0 unfocused raw SAR data
L1 RSLCLevel 1 Focused SAR image in range-doppler coordinates (zero-doppler steered)
L1 RIFGLevel 1 phase-wrappted interferogram in range-doppler coordinates (zero-doppler steered)
L1 RUNWLevel 1 phase-unwrapped interferogram in range-doppler coordinates (zero-doppler steered)
L1 ROFFLevel 1 pixel offsets in range-doppler coordinates (zero-doppler steered)
L2 GSLCLevel 2 Focused SAR image in geocoded coordinates
L2 GUNWLevel 2 phase-unwrapped interferogram in geocoded coordinates
L2 GOFFLevel 2 pixel offsets in geocoded coordinates
L2 GCOVLevel 2 SAR covariance product in geocoded coordinates
L3 SMLevel 3 Global Soil Moisture Product
Chart showing anticipated NISAR products with L0 on left and L3-4 on right

NISAR data product levels. Products through Level 2 will be produced for the entire mission dataset. Products at higher levels will be produced by the science team for calibration and validation purposes. Credit: NISAR Mission Science Users' Handbook, August 2019, Version 1.

Synthetic Aperture Radar (SAR)

  • L-Band (provided by NASA)
  • S-Band (provided by ISRO)

L-Band SAR

The NISAR system comprises a dual frequency, fully polarimetric radar, with an imaging swath greater than 150 miles (240 km). This design permits complete global coverage every 12-days.

The focus of NASA's science goals for NISAR is the 24-cm-wavelength, side-looking, fully polarimetric, interferometric L-Band SAR supplied by NASA’s Jet Propulsion Laboratory (JPL). The L-Band SAR will be used globally to meet all of NASA’s science requirements. Current mission observing scenarios call for the instrument to be on while collecting data for 45% to 50% of each orbit on average, with peaks as high as 70%. The L-Band SAR is capable of 242-kilometer swaths with 7-meter resolution along track and 2- to 8-m resolution cross-track, depending on the viewing mode. This radar comprises 24 L-band transmit/receive array elements in 2 rows, 12 per polarization.

The instrument’s pointing accuracy is such that L-Band SAR data can be used to produce repeat-pass interferograms sensitive to large-scale land deformation rates as small as 4 mm/year. To meet the requirements of all science disciplines, the L-Band SAR is designed to deliver fast sampling, global access and coverage, at full resolution and with polarimetric diversity.

S-Band SAR

The 9.3 cm wavelength S-Band SAR supplied by ISRO is the secondary radar and is composed of 48 S-Band transmit/receive array elements in 2 rows, 24 per polarization. The S-Band SAR will be used to produce data over science areas of interest to India that are above and beyond the NASA requirements. The areas include coastal bathymetry and ocean winds, geology over India, and coastal shoreline studies. The S-Band instrument is also sensitive to light vegetation and will be used in polar regions, as its signal is less sensitive to ionospheric disturbances.

L-Band: 1.25 GHz; 24 cm wavelength; polarimetric SAR

  • SP: HH or VV
  • DP: HH/HV or VV/VH
  • CP: RH/RV
  • QP (Quad Pol): HH/HV/VH/VV

 

S-Band: 3.20 GHz; 12 cm wavelength; polarimetric SAR

  • SP (Single Pol): HH or VV 
  • DP (Dual Pol): HH/HV or VV/VH 
  • CP (Compact Pol): RH/RV 
  • QQP (Quasi-Quad Pol):HH/HV and VH/VV
ParametersS-BandL-Band
Orbit747 km with 98° inclination
Repeat Cycle12 days
Time of Nodal Crossing6 a.m./6 p.m.
Frequency3.2 GHz ± 37.5 MHz1.257 GHz ± 40 MHz
Available Polarmetric Modes

Single Pol (SP): H or VV

Dual Pol (DP: HH/HV or VV/VH

Compact Pol (CP): RH/RV

Quasi-Quad Pol (QQP): HH/HV and VH/VV

SP: HH or VV

DP: HH/HV or VV/VH

CP: RH/RV

Quad Pol (QP): HH/HV/VH/VV

Available Range Bandwidths10 MHz, 25 MHz, 37.5 MHz, 75 MHz5 MHz, 20 MHz, 40 MHz, 80 MHz (additional 5 MHz iono band for 20 and 40 MHz modes at other end of pass-band)
Swath Width>240 Km (except for QQP mode)>240 Km (except for 80 MHz BW)
Spatial Resolution7 m (Az); 3 m - 24 m (Slant-Ra)7 m (Az); 3 m - 48 m (Slant-Ra)
Incidence Angle Range37-47 deg37-47 deg
Noise Equivalent 

-25 dB (baseline)

-20 dB (threshold)

-25 dB (for required full-swath modes)
Ambiguities<-20 dB for all modes except QQP

<-23 dB swath average in SP or DP modes

<-17 dB swath average in QP modes

Data Product AccessFree and Open

NISAR has a ~ 240 km swath, 7 m resolution along track and 2-8 m resolution cross-track (depending on mode).

Simulated NISAR Data Products

Simulated NISAR products are generated from Uninhabited Aerial Vehicle SAR (UAVSAR) data to emulate NISAR data characteristics in order to help users test their algorithms and get a sense of the quality of future NISAR products.

The simulated NISAR product names conform to the following naming convention: Sitename_LineID_FlightID_DT_Date_BandSquintPol_XtalkDither_NMode_Version.Ext
This adds the field NMode to the standard UAVSAR PolSAR naming convention.

Field NameCharactersField Description
Sitename6Abbreviated name for the target site
LineID5ID that describes a unique track, where the first 3 digit aircraft heading is followed by a 2 character incremental counter.
FlightID5Flight ID describing the unique flight the line is flown in, where the first two digits are the last two digits of the year, and the next three digits are the flight number counted sequentially from the first flight of the year.
DT3Data take counter indicating which acquisition during the flight this data was from, counted sequentially from the beginning of the flight and starting from zero.
Date6Acquisition date in YYMMDD format indicating the year, month, and day the data was collected in UTC time.
BandSquintPol4A single character indicating the frequency band, followed by the steering angle (three digits), sometimes followed by the polarization. If applicable, the polarization may be between 2 characters (first character is the transmit polarization, and second character is the receive polarization) and 4 characters (if the file represents a cross product)
Xtalk1Indicates whether cross talk has been calibrated or not: X - no crosstalk calibration, C - cross talk calibration has been applied.
Dither1Indicates whether the data has been dithered or not: X - not dithered, G - dithered with gaps, D - dithered with no gaps.
NMode4NISAR mode, where a 3-digit mode number associated a specific center frequency, bandwidth, and polarization, is followed by 1-digit character indicating the frequency (A or B).
Version2UAVSAR product version number. Increments with new product release of the same acquisition.
Ext2-5File extension

NISAR data will be fully and openly available to global data users in keeping with NASA's open data policies.

Frequently Asked Questions

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