Astronomy & Space Technology

Context: Indian Space Research Organisation (ISRO) plans to launch the Chandrayaan-3 mission, India’s third lunar mission, to the moon on July 14. 

Chandrayaan-3: 

• Chandrayaan-3 is a follow-on mission to Chandrayaan-2 to demonstrate end-to-end capability in safe landing and roving on the lunar surface. 
• It will be launched onboard a Launch Vehicle Mark 3 from Sriharikota, Andhra Pradesh. 
• Cost of the mission: Rs 615 crore
• Duration: The mission is only meant to last for a half lunar day, which is roughly equal to 14 Earth days. 

Objectives: 

• To demonstrate a Safe and Soft Landing on Lunar Surface (near the lunar South Pole).
• To demonstrate Rover roving on the moon (which will carry out in-situ chemical analysis of the lunar surface during the course of its mobility)
• To conduct in-situ scientific experiments.

Soft-landing on Moon:

• This will be India’s second attempt to soft-land a lander and rover on the lunar surface.
  • Chandrayaan-2 was launched in July 2019 in the form of an orbiter and a lander (‘Vikram’) bearing a rover (‘Pragyan’).
  • While the orbiter entered into orbit around the moon, the surface mission failed in September 2019 when the lander crashed instead of executing a slow descent.
• Chandrayaan-3 consists of a Lander and a Rover similar to Chandrayaan-2, but would not have an orbiter.
  • The rocket (LVM-3) will place the payload in an elliptical orbit around the earth, where a propulsion module will take over and pilot the lander to a circular orbit around the moon.
  • Finally, the lander will detach and begin a series of manoeuvres culminating in a gradual landing (on August 23-24, 2023) over the surface of the moon.
• To improve the chances of success at this stage, ISRO made changes to the software and hardware of the Chandrayaan-3 mission, especially for the lander thrusters. Additionally, ISRO has developed improved soft-landing sequences and the lander has four thruster engines instead of five, sturdier legs and larger solar panels, and will carry more fuel.

Several advanced technologies in Chandrayaan-3:

• Propulsion module has a Spectro-polarimetry of Habitable Planet Earth (SHAPE) payload to gather data on the polarisation of light reflected by Earth so that researchers can look for other planets with similar signatures. Hence, it will assist with exoplanet searches. 
• Lander payloads:
  • Chandra's Surface Thermophysical Experiment (ChaSTE) to measure thermal conductivity and temperature on the surface;
  • Instrument for Lunar Seismic Activity (ILSA) to detect moonquakes;
  • Langmuir Probe to estimate the density and variation of plasma, or superheated gas, in the moon's environment; 
  • A Laser Retroreflector Array (from NASA) to measure distances using laser ranging to understand the dynamics of the Moon system. 
• Rover payloads:
  • Alpha Particle X-ray Spectrometer (APXS) to look for elements in the lunar soil and rocks;
  • Laser Induced Breakdown Spectroscope (LIBS) to examine the chemical and elemental composition of the lunar surface.

Significance of Chandrayaan-3:

• Chandrayaan-3 offers opportunities for India to lead the world’s response to the moon’s growing importance in the scientific and political milieus.
  • Chandrayaan-3 is India’s second attempt to achieve a soft landing on the Moon’s surface. Only three countries – the United States, Russia and China – have successfully landed spacecraft on the airless lunar surface.
  • Chandrayaan-3 will be the first to land on the South Pole of the Moon. All other spacecraft which have landed on the moon have landed in the equatorial region, a few degree latitude north or south of the lunar equator. 

Why moon’s South Pole? 

• Experts note that there is a possibility of the presence of water at the South Pole. Water ice has been detected at both poles of the Moon, but the South Pole has more area in permanent shadow and colder temperatures, so it is thought to have more water ice.
• Moreover, the South Pole witnesses extremely cold temperatures; this means that anything trapped here would remain frozen in time, without undergoing much change. The rocks and soil in this region could therefore provide clues to the early solar system.

Further, South Pole is located in the South Pole-Aitken basin, which is a huge crater. There may be material from the deep crust and upper mantle of the Moon on or near the surface.

Context: An international team of astronomers from India, Japan, and Europe has published the results from monitoring pulsars, called nature’s best clocks, by using six of the world’s most sensitive radio telescopes, including India’s largest telescope, the Pune-based Giant Metrewave Radio Telescope (GMRT) provides evidence confirming the presence of nano-hertz (ultra-low frequency) gravitational waves using pulsar observations.

About GMRT

• It is a low-frequency radio telescope that helps investigate various radio astrophysical problems ranging from nearby solar systems to the edge of the observable universe. 
• It is an array of thirty fully steerable parabolic radio telescopes of 45-metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies.
• It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research, Mumbai.
• It is located near Narayangaon, Pune.
• Astronomers from all over the world regularly use this telescope to observe many different astronomical objects such as HII regions, galaxies, pulsars, supernovae, and Sun and solar winds.
• It was recently upgraded with new receivers, after which it is also known as the upgraded Giant Metrewave Radio Telescope (uGMRT).

Context: The European Space Agency (ESA) plans to survey billions of galaxies using the Euclid Space Telescope, which is due to launch on July 1 from Cape Canaveral in Florida on a SpaceX Falcon 9 rocket.

Euclid Mission:

• The mission is part of ESA’s ‘Cosmic Vision’ programme which plans to explore the origin and components of the Universe and the laws that govern it.

• The payload will have a 1.2 metre-wide telescope, a visible-wavelength camera (VISible) and a near-infrared camera/spectrometer (NISP).
  • VISible will look for tiny distortions in the shapes of distant galaxies from different points in time to understand the tussle between the pull of gravity and the push of dark energy.
  • NISP will look at how quickly galaxies are moving away from each other, offering scientists insights into the effects of gravity. 
• Stationed 1.5 million km away from the Earth, the telescope is expected to deliver images at least four times sharper than ground-based observatories.
• The Euclid mission hopes to understand the evolution of the Universe by looking at the light emitted from galaxies 10 billion years ago. Euclid's main objective is to better understand dark matter and dark energy, which together make up 95% of the universe.

Dark Energy:

• Around 68% of the Universe is made of dark energy while dark matter makes up 27%. Only the remainder is composed of fermionic matter, i.e., things on the Earth, planets, stars, etc.
• Scientists theorised the existence of dark energy 25 years ago when a team of researchers found that instead of slowing down due to gravity (inwards pulling force), the expansion of the Universe was speeding up. Scientists hypothesised that this was happening due to a mysterious form of energy called dark energy.
  • The expansion of the universe is accelerating. Previously it was thought that the pull of gravity will either slow down or even retract the expansion.
  • Dark energy has been hypothesised as a repulsive force — a sort of anti-gravity. As our universe is expanding, it indicates that Dark Energy has a greater abundance than dark matter.
• Dark energy is a property of space so does not get diluted as space expands. As more space comes into existence, more of this energy-of-space appears. As a result, dark energy causes the universe to expand faster and faster.
• While Dark matter exerts a “pull” on the universe, Dark Energy has a contrasting expansionary effect.

Dark Matter:

• Dark matter has not yet been observed directly. It does not interact with matter and is completely invisible to light and other forms of electromagnetic radiation making it impossible to detect.
• Scientists are confident it exists because of the gravitational effects it has on galaxies and galaxy clusters.

Context: Researchers have traced a very significant increase in special continuous oscillations with pearl-type structures called Geomagnetic Pc1 pearl oscillations on the surface of the Earth in the recovery phase of geomagnetic storms. This study is significant for investigating of precipitation particles during geomagnetic storms and can help us understand the radiation hazard to satellites and astronauts.

What are geomagnetic storms?

• A geomagnetic storm is a major disturbance of Earth's magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth. 
• These storms result from variations in the solar wind that produces major changes in the currents, plasmas, and fields in Earth’s magnetosphere. 
• The solar wind conditions that are effective for creating geomagnetic storms:
  • Sustained (for several to many hours) periods of high-speed solar wind. 
  • Southward directed solar wind magnetic field (opposite the direction of Earth’s field) at the dayside of the magnetosphere. This condition is effective for transferring energy from the solar wind into Earth’s magnetosphere.
  • High-speed solar wind stream (HSS).
• The largest storms that result from these conditions are associated with solar coronal mass ejections (CMEs) where a billion tons or so of plasma from the sun arrives at Earth. 
• Storms also result in intense currents in the magnetosphere, changes in the radiation belts, and changes in the ionosphere, including heating the ionosphere and upper atmosphere region called the thermosphere. 

How Solar flares are formed?

Impacts of such storms:

• Increase in the density in the upper atmosphere, causing extra drag on satellites in low-earth orbit. 
• Horizontal variations in the in the ionospheric density that can modify the path of radio signals and create errors in the positioning information provided by GPS. 
• Storms create beautiful aurora. 
• They also can disrupt navigation systems such as the Global Navigation Satellite System (GNSS).
•  They can create harmful geomagnetic induced currents (GICs) in the power grid and pipelines.

What is Magnetosphere?

• It is the region around a planet dominated by the planet's magnetic field. Other planets in our solar system have magnetospheres, but Earth has the strongest one of all the rocky planets.
• Earth's magnetosphere is a vast, comet-shaped bubble, which shields our home planet from solar and cosmic particle radiation, as well as erosion of the atmosphere by the solar wind - the constant flow of charged particles streaming off the sun. 
• It is generated by the convective motion of charged, molten iron, far below the surface in Earth's outer core. 
• Constant bombardment by the solar wind compresses the sun-facing side of our magnetic field. The sun-facing side, or dayside, extends a distance of about six to 10 times the radius of the Earth. The side of the magnetosphere facing away from the sun - the nightside - stretches out into an immense magnetotail, which fluctuates in length and can measure hundreds of Earth radii, far past the moon's orbit at 60 Earth radii.

Difference between Ionosphere and Magnetosphere?

• The ionosphere is a region within the upper mesosphere and thermosphere where solar radiation and particles in the "solar wind" strip electrons from atoms in the atmosphere and create an electrically charged zone of ions. It is used to communicate long distances by radio. Radio waves bounce off the ionosphere in much the same way that light is reflected by a mirror. The ionosphere changes its position from day to night, rising in the night and lowering in the day. This is why radio signals from far off places can be detected at night, while only close by transmissions are detectable during the day.
• The magnetosphere is Contained within the Earth's thermosphere and is the region where the Earth’s magnetic field interacts with the charged particles coming from the Sun in the solar wind. These particles become trapped in the magnetic field of the Earth and circulate around the Earth following the Earth’s magnetic field. Large bombardments of these charged particles cause the auroras in the ionosphere as they follow the Earth’s magnetic field through the upper atmosphere towards the magnetic poles.

What are Van Allen radiation belts?

• The Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind. The particles are captured by and held around a planet by that planet’s magnetic field. It surrounds Earth, containing a nearly impenetrable barrier that prevents the fastest, most energetic electrons from reaching Earth.
• The outer belt is made up of billions of high-energy particles that originate from the Sun and become trapped in Earth’s magnetic field, an area known as the magnetosphere. The inner belt results from interactions of cosmic rays with Earth’s atmosphere.