A Low Earth Orbit (LEO) observatory being collaboratively constructed by NASA and ISRO is called NASA-ISRO SAR (NISAR). To comprehend changes in Earth's ecosystems, ice mass, vegetation biomass, sea level rise, ground water, and natural hazards including earthquakes, tsunamis, volcanoes, and landslides, NISAR will map the entire planet in 12 days. It will also give geographically and temporally consistent data. NISAR. It is equipped with L and S dual band Synthetic Aperture Radar (SAR), which uses the sweep SAR technique to produce high resolution data over a wide swath. An observatory is the collective name for the SAR payloads mounted on the Integrated Radar Instrument Structure (IRIS) and the spacecraft bus. In addition to fulfilling their respective national requirements, Jet Propulsion Laboratories and ISRO are building an observatory that will provide the scientific community with data that will support studies relating to surface deformation measurements made using the repeat-pass InSAR technique.
Flagship
Partnership
Both organisations
would make significant contributions to this flagship relationship. The L-Band
SAR payload system will be supplied by NASA, while the S-Band SAR payload will
be provided by ISRO. Both of these SAR systems will use a large size (about 12m
in diameter) common unfurl able reflector antenna. NASA would also supply
engineering payloads for the project, including as a Solid State Recorder, GPS
receivers, Payload Data Subsystem, and High-rate Science Downlink System.
In order to deliver L
& S band space-borne SAR data with high repeat cycle, high resolution, and
broader swath, as well as the capacity of full-polar metric and interferometric
modes of operation, this mission would be the first dual frequency radar
imaging mission in L & S band. It will give a way to unravel and make sense
of spatially and temporally complex occurrences, from ecosystem disruptions to
the melting of ice sheets and natural disasters like earthquakes, tsunamis,
volcanoes, and landslides. This is anticipated to give the rapidly developing
geosciences applications of microwave remote sensing a boost. The mission's
precise interferometric orbits will make it possible to map minor land surface
deformations of a few millimetres. The choice of lower frequency bands will
meet the demand for improved vegetation classification, which is essential for
estimating the global carbon stock and tracking carbon fluxes from vegetation.
In a similar vein, the choice of L- and S-band frequencies will allow
characterising objects under tree canopy and sub-surface characteristics due to
differential penetration of the signals in two frequency bands. The three
disciplines of ecosystems (vegetation and the carbon cycle), deformation
(studying solid Earth), and cryosphere sciences (mainly in relation to climatic
factors and effects on sea level) are being studied by NISAR as concepts for a
Synthetic Aperture Radar mission to ascertain Earth change. Data will be
collected over the Indian Coasts by NISAR, which will also track yearly
variations in bathymetry in the deltaic zones. Additionally, the shoreline and
erosion accumulation will be watched. The NISAR project will monitor sea ice
features across the waters around India's polar installations in Antarctica. It
can be used to locate marine oil spills and discover them early enough to take
preventative action.
The JPL-developed
deployable 9-meter boom set on a 12-meter wide deployable mesh reflector is
carried by the NISAR observatory and will be used by both-Both the L-band and
S-band SAR payload systems were designed by JPL-NASA and ISRO, respectively.
The S-SAR and L-SAR tiles, as well as their electronic and data handling
systems, are housed in the IRIS. The spaceship includes all of the power
systems, thermal management systems, and attitude and orbit control components.
JPL will also supply GPS receivers, a Solid State Recorder, a High-rate Science
data Downlink System, and LSAR Data Handling System. The SSAR data handling
system, High rate downlink system, satellite bus systems, GSLV launch system,
and Mission Operations Related Services are all provided by ISRO. NISAR is a
flawless fusion of two cultures and a product of two teams of artisans.
The three phases of
NISAR's development are listed below. During SIT-2, the engineering systems and
SAR payloads must be independently developed in their respective soils. The SAR
payload and other connected equipment will be integrated with the radar
instrument structure during the SIT-3 phase and evaluated at JPL. ISRO is
carrying out parallel initiatives for the realisation and testing of spacecraft
systems. ISRO is responsible for the ensuing tasks of integrating IRIS with the
spacecraft and evaluating it as an observatory. This is the SIT-4 phase, which
is currently in progress. JPL is preparing to ship the IRIS, while the
spacecraft is preparing to receive its counterpart. The SIT-4 testing phase
will be particularly detailed and crucial, as the entire observatory's
performance will be evaluated during this phase. The NISAR observatory will be launched
from Indian soil in the first quarter of 2024, and the data gathered will
undoubtedly assist the scientific community.
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| Officials from NASA |
LAUNCH PHASE
On the GSLV expendable
launch vehicle provided by ISRO, the NISAR Observatory will be launched from
Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota on the southeast coast of
the Indian peninsula. The launch is anticipated to be ready in January 2024.
The launch sequence starts with the observatory on the ground, enclosed in the
launch vehicle fairing, and ends with the solar arrays fully deployed, the
observatory in an Earth-pointing attitude, and the observatory in two-way
communication with the ground. A crucial event is the launch sequence.
COMMISSIONING
PHASE
Commissioning, also
known as in-orbit checkout (IOC), will take place within the first 90 days
following launch with the aim of getting the observatory ready for scientific
operations. Initial checkout (ISRO engineering systems and JPL engineering
payload checkout), spacecraft checkout, and instrument checkout are the three
sub-phases of commissioning. The sub-phases are conceptualised as a gradual
increase in capability leading up to full observatory operations, starting with
the physical deployment of all deployable parts (particularly the boom and
radar antenna, but excluding the solar arrays, which are deployed during launch
phase), checking the engineering systems, turning on the radars and testing
them separately, and finally conducting joint tests with both radars
operational.
SCIENCE
OPERATIONS PHASE
The three-year science
operations phase, which starts after commissioning, includes all data gathering
necessary to meet the L1 science objectives. Regular manoeuvres will be
performed during this phase to maintain the science orbit while avoiding or
reducing interference with scientific observations. The first five months will
be filled with a lot of calibration and validation (CalVal) work, with yearly
upgrades lasting one month. Pre-launch engineering operations (such as
manoeuvres, parameter changes, etc.) and the observation plan for both L- and
S-band sensors will be generated through frequent cooperation between JPL and
ISRO. The science observations made solely as part of this plan are referred to
as the reference observation plan (ROP), which is also known as the reference
mission. A number of factors, such as L- and S-band target maps, radar mode
tables, spacecraft and ground-station limits and capabilities, will influence
the timetable of science observations. The project will try to fly the
reference mission, which includes these science observations exactly as planned
prior to launch (accommodating for modest temporal adjustments based on the
actual orbit), according to this schedule, which will be decided by JPL's
mission planning team.