Type: Prelims Only

The NASA-ISRO Synthetic Aperture Radar satellite, aimed at making global measurement of land surface changes using advanced radar imaging, is proposed to be launched in early 2023, informed Earth Sciences Minister.

Note the key features of the Mission. Every statement has a unique information.

NASA-ISRO SAR

• NISAR is a joint collaboration for a dual-frequency L and S-band SAR for earth observation.
• NASA and Bengaluru-headquartered ISRO signed a partnership on September 30, 2014, to collaborate on and launch NISAR.
• The mission is targeted to launch in early 2022 from ISRO’s Sriharikota spaceport in Andhra Pradesh’s Nellore district, about 100km north of Chennai.
• It is capable of producing extremely high-resolution images for a joint earth observation satellite mission with NASA.
• It will be the first satellite mission to use two different radar frequencies (L-band and S-band) to measure changes in our planet’s surface less than a centimeter across.

Objectives of the NISAR

• NISAR will observe Earth’s land and ice-covered surfaces globally with 12-day regularity on ascending and descending passes, sampling Earth on average every six days for a baseline three-year mission.
• It will measure Earth’s changing ecosystems, dynamic surfaces, and ice masses, providing information about biomass, natural hazards, sea-level rise, and groundwater, and will support a host of other applications.
• It would also provide data on natural hazards including earthquakes, tsunamis, volcanoes, and landslides.

What are L and S Bands?

• L band waves are used for GPS units because they are able to penetrate clouds, fog, rain, storms, and vegetation.
• The S-band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station.
• NISAR uses a sophisticated information-processing technique known as SAR to produce extremely high-resolution images.
• Radar penetrates clouds and darkness, enabling NISAR to collect data day and night in any weather.

What is collaboration?

• NASA is providing the mission’s L-band SAR, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem.
• ISRO is providing the spacecraft bus, the S-band radar, the launch vehicle, and associated launch services for the mission, whose goal is to make global measurements of the causes and consequences of land surface changes using advanced radar imaging.

Geo-imaging satellite for earth observation EOS-03, which would enable near real-time monitoring of natural disasters like floods and cyclones, is scheduled for launch in the third quarter of 2021.

EOS-03

• ISRO has realized a geo-imaging satellite, “EOS-03”, for Earth Observation from Geostationary Orbit.
• EOS-03 is capable of imaging the whole country four-five times daily and would enable near real-time monitoring of natural disasters like floods and cyclones.
• In addition to natural disasters, EOS-03 would also enable monitoring of water bodies, crops, vegetation condition, forest cover changes.

Other developments: Small Satellite Launch Vehicle (SSLV)

• The first developmental flight of the Small Satellite Launch Vehicle (SSLV) is scheduled for the fourth quarter of 2021 from the Satish Dhawan Space Centre, Sriharikota.
• The SSLV is a cost-effective, three-stage and all-solid launch vehicle with a payload capability of 500 kg to 500 km planar orbit or 300 kg to Sun-Synchronous Polar Orbit.
• It is ideal for the on-demand, quick turn-around launch of small satellites.
• The major technologies developed as part of SSLV are flexible nozzle control with electro-mechanical actuators for all stages, miniaturized avionics, and a velocity trimming module in the upper stage for precise satellite injection.

Scientists for the first time have spotted a Moon-forming region around an exo-planet beyond our solar system.

What are Exoplanets?

• More than 4,400 planets have been discovered outside our solar system, called exoplanets.
• Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star.
• No circumplanetary discs had been found until now because all the known exoplanets resided in “mature” – fully developed – solar systems, except the two infant gas planets orbiting PDS 70.

What is the new finding?

• The researchers have detected a disc of swirling material accumulating around one of two newborn planets.
• They were seen orbiting a young star called PDS 70, located a relatively close 370 light-years from Earth.
• It is called a circumplanetary disc, and it is from these those moons are born.
• The discovery offers a deeper understanding of the formation of planets and moons.

Focus of the finding: Formation of disc

• In our solar system, the impressive rings of Saturn, a planet around which more than 80 moons orbit, represent a relic of a primordial moon-forming disc.
• The orange-colored star PDS 70, roughly the same mass as our Sun, is about 5 million years old– a blink of the eye in cosmic time.
• The two planets are even younger. Both planets are similar (although larger) to Jupiter, a gas giant.
• It was around one of the two planets, called PDS 70c, that a Moon-forming disc was observed.

Observing birth of a moon: Core Accretion

• Stars burst to life within clouds of interstellar gas and dust scattered throughout galaxies.
• Leftover material spinning around a new star then coalesces into planets, and circumplanetary discs surrounding some planets similarly yield moons.
• The dominant mechanism thought to underpin planet formation is called “core accretion”.
• In this scenario, small dust grains, coated in ice, gradually grow to larger and larger sizes through successive collisions with other grains.
• This continues until the grains have grown to a size of a planetary core, at which point the young planet has a strong enough gravitational potential to accrete gas which will form its atmosphere.
• Some nascent planets attract a disc of material around them, with the same process that gives rise to planets around a star leading to the formation of moons around planets.
• The disc around PDS 70c, with a diameter about equal to the distance of the Earth to the sun, possesses enough mass to produce up to three moons the size of Earth’s moon.