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27th Mar 2023

NASA’s ICESat-2 maps Antarctic ice sheet melting

ICESat-2 

• NASA’s ICESat-2 launched less than three months ago has mapped melting ice sheets in Antarctica and the resulting sea level rise across the globe, which could help improve climate forecasts.
• The ICESat-2 stands for Ice, Cloud and land Elevation Satellite-2 .
• It is measuring the height of sea ice to within an inch, tracing the terrain of previously unmapped Antarctic valleys, surveying remote ice sheets, and peering through forest canopies and shallow coastal waters.
• With each pass of the ICESat-2 satellite, the mission is adding to datasets tracking Earth’s rapidly changing ice.
• As ICESat-2 orbits over the Antarctic Ice Sheet, the photon returns reflect from the surface and show high ice plateaus, crevasses in the ice 20 metres deep, and the sharp edges of ice shelves dropping into the ocean.

Unified Geologic Map of the Moon

• The first-ever digital, unified, global, geological map of the moon was released virtually by the  United States Geological Survey (USGS), NASA and the Lunar Planetary Institute.
• The UGM will serve as a blueprint for future human missions and a source of research and analysis for the educators and the general public interested in lunar geology.
• The map is a ‘seamless, globally consistent, 1:5,000,000-scale geologic map’.
• The mapped surface features of the moon included crater rim crests, buried crater rim crests, fissures, grabens, scarps, mare wrinkle ridges, faults, troughs, rilles, and lineaments.

Its’ significance

• The moon’s South Pole is especially interesting because the area is much larger than the North Pole and there could be a possibility of the presence of water in these permanently shadowed areas.
• Further, the South Pole region also contains the fossil record of the early Solar System.
• These present and future moon missions’ success can be further helped by the digital map of the moon.
• The Chandrayaan 2, an active mission also targets the Lunar South Pole for exploration

GRACE-FO Mission

• The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission is a partnership between NASA and the German Research Centre for Geosciences (GFZ).
• GRACE-FO is a successor to the original GRACE mission, which orbited Earth from 2002-2017.
• It carries on the extremely successful work of its predecessor while testing a new technology designed to dramatically improve the already remarkable precision of its measurement system.

Fast Radio Bursts (FRBs)

• FRBs are super intense, millisecond-long bursts of radio waves produced by unidentified sources in the space.
• Their discovery in 2007 by American astronomer Duncan Lorimer led to the term ‘Lorimer Bursts’.
• Since then, just a few dozen similar events have been observed in data collected by radio telescopes around the world, building evidence that points to a variety of potential causes.
• Only a handful of emissions have been traced to specific areas of the sky, indicating sources in other galaxies.
• The flash of radio waves is incredibly bright if distant, comparable to the power released by hundreds of millions of suns in just a few milliseconds.
• This intensity suggests powerful objects like black holes and neutron stars could be involved.
• The events were once considered to be largely transient – they seemed to happen once, without obvious signs of a repeat emission. However, a number of such bursts have been identified since then.

Why are they significant?

• First noticed in 2018 by the Canadian observatory the waves have created ripples across the globe for one reason — they arrive in a pattern.
• This gave birth to theories that they could be from an alien civilization.
• Initially, it was believed that the collision of black holes or neutron stars triggers them.
• But the discovery of repeating FRBs debunked the theory of colliding objects.

NASA’s new Mars rover: Perseverance

• The Perseverance rover weighs less than 2,300 pounds and is managed by NASA’s Jet Propulsion Lab.
• The rover’s mission will be to search for signs of past microbial life. It will also collect samples of Martian rocks and dust, according to the release.
• The rover will also be tasked with studying the red planet’s geology and climate.
• All of NASA’s previous Mars rovers — including the Sojourner (1997), Spirit and Opportunity (2004) and Curiosity (exploring Mars since 2012) — were named in this way.

2020 CD3

• The mini-moon was discovered by some astronomers at NASA-funded Catalina Sky Survey (CSS) in Arizona.
• It is actually an asteroid, about the size of a car; its diameter is about 1.9-3.5 m.
• And unlike our permanent Moon, the mini-moon is temporary; it will eventually break free of Earth’s orbit and go off on its own way.
• Orbit integrations indicate that this object is temporarily bound to the Earth.
• 2020 CD3 was captured into Earth’s orbit over three years ago.
• For CSS, it is only the second such discovery. It previously discovered 2006 RH120, which orbited Earth for some time that year, before it escaped in 2007.

NASA’s InSight Mission

• The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission is a robotic lander designed to study the deep interior of the planet Mars.
• It is the first mission dedicated to looking deep beneath the Martian surface.
• Among its science tools are a seismometer for detecting quakes, sensors for gauging wind and air pressure, a magnetometer, and a heat flow probe designed to take the planet’s temperature.
• The InSight mission is part of NASA’s Discovery Program.
• It is being supported by a number of European partners, which include France’s Centre National d’Études Spatiales (CNES), the German Aerospace Center (DLR) and the United Kingdom Space Agency (UKSA).

Habitable-zone Planet Finder

• NASA’s Kepler mission observed a dip in the host star’s light, suggesting that the planet was crossing in front of the star during its orbit.
• To confirm, researchers turned to an instrument called Habitable-zone Planet Finder (HPF). It has confirmed that there is indeed an exoplanet.
• HPF is an astronomical spectrograph, built by Penn State University scientists, and recently installed on the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas.
• The instrument is designed to detect and characterize planets in the habitable zone — the region around the star where a planet could sustain liquid water on its surface — around nearby low-mass stars.
• The newly confirmed planet, called G 9-40b, is the first one validated by HPF. It is about twice the size of Earth and orbits its star once every six Earth-days.

 Betelgeuse

• Using the European Space Organization’s (ESO) Very Large Telescope (VLT), astronomers have noticed the unprecedented dimming of Betelgeuse.
• It is a red supergiant star (over 20 times bigger than the Sun) in the constellation Orion.
• Along with the dimming, the star’s shape has been changing as well, as per recent photographs of the star taken using the VISIR instrument on the VLT.
• Instead of appearing round, the star now appears to be “squashed into an ova”.

NASA announced it has selected four Discovery Program investigations to develop concept studies for possible new missions.

What are the new missions?

• Two proposals are for trips to Venus, and one each is for Jupiter’s moon Io and Neptune’s moon Triton.
• After the concept studies are completed in nine months, some missions ultimately may not be chosen to move forward.

DAVINCI+

• DAVINCI+ stands for Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus.
• This will analyse Venus’s atmosphere to understand how it was formed and evolved, and if it ever had an ocean.
• This will advance understanding of the formation of terrestrial planets.

IVO

• Io Volcano Observer is a proposal to explore Jupiter’s moon Io, which is extremely volcanically active.
• This will try to find out how tidal forces shape planetary bodies.
• The findings could further knowledge about the formation and evolution of rocky, terrestrial bodies and icy ocean worlds in the Solar System.

TRIDENT

This aims to explore Neptune’s icy moon, Triton, so that scientists can understand the development of habitable worlds in the Solar System.

VERITAS

Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy will aim to map Venus’s surface to find out why Venus developed so differently from Earth.

Pale Blue Dot

• The ‘Pale Blue Dot’ is one of the most iconic images in the history of astronomy.
• It shows Earth as a single bright blue pixel in empty space within a strand of sun rays, some of which are scattering from and enlightening the planet.
• The original image was taken by the Voyager 1 mission spacecraft on February 14, 1990 when it was just beyond Saturn.
• At the behest of astronomer Carl Sagan, the cameras were turned towards Earth one final time to capture the image.
• After this, the cameras and other instruments on the craft were turned off to ensure its longevity.

About Voyager 1

• Voyager 1 is a space probe launched by NASA on September 5, 1977.
• Having operated for more than 42 years, the spacecraft still communicates with the Deep Space Network to receive routine commands and to transmit data to Earth.
• At a distance of 148.67 AU (22.2 billion km) from Earth as of January 19, 2020 it is the most distant man-made object from Earth.
• The probe’s objectives included flybys of Jupiter, Saturn, and Saturn’s largest moon, Titan.

The Family Portrait of the Solar System

• The Pale blue dot image was a part of a series of 60 images designed to produce what the mission called the ‘Family Portrait of the Solar System’.
• This sequence of camera-pointing commands returned images of six of the solar system’s planets, as well as the Sun.

Solar Orbiter (SolO) Probe

• The Solar Orbiter, a collaborative mission between the European Space Agency and NASA to study the Sun, took off from Cape Canaveral in Florida.
• Carrying four in situ instruments and six remote-sensing imagers, the Solar Orbiter (called SolO) will face the sun at approximately 42 million kilometres from its surface.
• Before SolO, all solar imaging instruments have been within the ecliptic plane, in which all planets orbit and which is aligned with the sun’s equator.
• The new spacecraft will use the gravity of Venus and Earth to swing itself out of the ecliptic plane, passing inside the orbit of Mercury, and will be able to get a bird’s eye view of the sun’s poles for the first time.

Spitzer Space Telescope

• The Spitzer Space Telescope is a space-borne observatory, one of the elements of NASA’s Great Observatories that include the Hubble Space Telescope and the Chandra X-Ray.
• Using different infrared wavelengths, Spitzer was able to see and reveal features of the universe including objects that were too cold to emit visible light.
• Apart from enabling researchers to see distant cold objects, Spitzer could also see through large amounts of gas using infrared wavelengths to find objects that may otherwise have been invisible to human beings.
• These included exoplanets, brown dwarfs and cold matter found in the space between stars.
• Spitzer was originally built to last for a minimum of 2.5 years, but it lasted in the “cold” phase for over 5.5 years. On May 15, 2009 the coolant was finally depleted and the “warm mission” began.

Thirty Metre Telescope

• The TMT is a proposed astronomical observatory with an extremely large telescope (ELT) that has become the source of controversy over its planned location on Mauna Kea on the island of Hawaii in the US state of Hawaii.
• It is being built by an international collaboration of government organisations and educational institutions, at a cost of $1.4 billion.
• “Thirty Metre” refers to the 30-metre diameter of the mirror, with 492 segments of glass pieced together, which makes it three times as wide as the world’s largest existing visible-light telescope.
• The larger the mirror, the more light a telescope can collect, which means, in turn, that it can “see” farther, fainter objects.
• It would be more than 200 times more sensitive than current telescopes and would be able to resolve objects 12 times better than the Hubble Space Telescope.

Artemis Mission

• In 2011, NASA began the ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun) mission using a pair of repurposed spacecraft and in 2012 the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft studied the Moon’s gravity.
• For the program, NASA’s new rocket called the Space Launch System (SLS) will send astronauts aboard the Orion spacecraft a quarter of a million miles away from Earth to the lunar orbit.
• The astronauts going for the Artemis program will wear newly designed spacesuits, called Exploration Extravehicular Mobility Unit, or xEMU.
• These spacesuits feature advanced mobility and communications and interchangeable parts that can be configured for spacewalks in microgravity or on a planetary surface.

Bhibha Constellation and Santamasa Planet

Bhibha

• The star has been named in honour of a pioneering Indian woman scientist Bibha Choudhury, who discovered subatomic particle, pi-meson.
• ‘Bhibha’ also means “a bright beam of light” in Bengali.
• It is located in the constellation of Sextans. It is as hot as the sun, with a surface temperature of about 6,000 degrees Kelvin. It is 1.55 times bigger, 1.21 times massive, and 1.75 times brighter.
• It is so far away that light from it takes 310.93 years to reach Earth and hence it is visible only with a telescope.

Santamasa

• The planet has been named S’antamasa’ to reflect the cloudy nature of its atmosphere. ‘Santamasa’ is the Sanskrit term for ‘clouded’.
• ‘Santamasa’, which is its only planet, is estimated to have a mass of 1.5 times that of Jupiter, going around the central star in a nearly circular orbit just in 2.1375 days.
• Revolving so near the host star, the planet is expected to be very hot.

Arrokoth

• The International Astronomical Union and Minor Planets Center, the global body for naming Kuiper Belt objects have given this name.
• It was discovered in 2014 with the Hubble Space Telescope, which is operated by the Space Telescope Science Institute in Baltimore.
• Nasa’s New Horizons spacecraft flew by the snowman figured ice mass in December 2018, some 1.6 billion kilometres beyond Pluto.
• The New Horizons team of NASA proposed the name to the International Astronomical Union and Minor Planets Center.
• For the New Horizons team it took some months to finalise this name. In the language of the Powhatan tribe, Arrokoth means “sky”.
• The team got the approval from the elders of the Powhatan tribe to assign it to their newfound “baby”.

About New Horizons mission

• NASA launched the New Horizons mission in January 2006.
• After crossing by Pluto in 2015, in 2019 it flew by Arrokoth. This remains the “farthest flyby ever conducted.”

Maxwell

• The Maxwell is the latest in a line of experimental aircraft the NASA.
• It has been developed over many decades for many purposes, including the bullet-shaped Bell X-1 that first broke the sound barrier and the X-15 rocket plane flown by Neil Armstrong before he joined the Apollo moon team.
• The two largest of 14 electric motors that will ultimately propel the plane are powered by specially designed lithium ion batteries.
• The Maxwell will be the agency’s first crewed X-plane to be developed in two decades.
• The lift propellers will be activated for take-off and landings, but retract during the flight’s cruise phase.

Voyager 2

• Voyager 2 was launched in 1977, 16 days before Voyager 1, and both have travelled well beyond their original destinations.
• The spacecraft were built to last five years and conduct close-up studies of Jupiter and Saturn.
• As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left Earth.
• It carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.
• It is slightly more than 18 billion kilometres from Earth. Its twin, Voyager 1, crossed this boundary in 2012.
• Their five-year lifespans have stretched to 41 years, making Voyager 2 NASA’s longest-running mission.

Ionospheric Connection Explorer

• NASA has launched a satellite to explore the mysterious, dynamic region where air meets space.
• The satellite — called ICON, short for Ionospheric Connection Explorer — rocketed into orbit following a two-year delay.
• The refrigerator-size ICON satellite will study the airglow formed from gases in the ionosphere and also measure the charged environment right around the spacecraft which is at a level of 580 kilometres above the Earth’s surface.
• The ionosphere is the charged part of the upper atmosphere extending several hundred miles (kilometres) up.
• It’s in constant flux as space weather bombards it from above and Earth weather from below, sometimes disrupting radio communications.

Lunar Reconnaissance Orbiter (LRO)

• The Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite missions began on June 18, 2009.
• It is a robotic spacecraft currently orbiting the Moon.
• It studies the Moon’s surface, clicks pictures, and collects data that help in figuring out the presence and possibility of water ice and other resources on the Moon, as well as plan future missions to it.
• The primary mission of the LRO, managed by NASA’s Goddard Space Flight Center, located in Greenbelt, Maryland, was to measure the entire lunar surface to create a high-resolution 3-D map of the Moon.
• The map with ~50-centimeter resolution images would aid in the planning of future robotic and crewed missions.
• In addition, LRO would map the Polar Regions and search for the presence of water ice

K2-18b

• About 110 light years from Earth, an exoplanet eight times the mass of Earth orbits a star. Called K2-18b, it was discovered in 2015 by NASA’s Kepler spacecraft.
• The researchers used 2016-17 data from the Hubble Space Telescope and developed algorithms to analyse the starlight filtered through K2-18b’s atmosphere.
• The results revealed the molecular signature of water vapour, also indicating the presence of hydrogen and helium in the planet’s atmosphere.
• It resides in a habitable zone — the region around a star in which liquid water could potentially pool on the surface of a rocky planet.
• Scientists have found signatures of water vapour in the atmosphere of K2-18b. The discovery of water vapour is not the final word on the possibility of life.
• That makes it the only planet orbiting a star outside the Solar System that is known to have both water and temperatures that could support life.

Asteroid Impact Deflection Assessment (AIDA)

• It is an ambitious double-spacecraft mission to deflect an asteroid in space, to prove the technique as a viable method of planetary defence.
• The mission, which includes NASA and the European Space Agency (ESA), is known as the Asteroid Impact Deflection Assessment (AIDA).
• The target is the smaller of two bodies in the “double Didymos asteroids” that are in orbit between Earth and Mars.
• Didymos is a near-Earth asteroid system. Its main body measures about 780 m across; the smaller body is a “moonlet” about 160 m in diameter.
• The project aims to deflect the orbit of the smaller body through an impact by one spacecraft.
• Then a second spacecraft will survey the crash site and gather the maximum possible data on the effect of this collision.

Parker Solar Probe

• It is part of NASA’s “Living with a Star” programme that explores different aspects of the Sun-Earth system.
• The probe seeks to gather information about the Sun’s atmosphere and NASA says that it “will revolutionise our understanding of the Sun”.
• It is also the closest a human-made object has ever gone to the Sun.
• During the spacecraft’s first two solar encounters, the instruments were turned on when Parker was about 0.25 AU from the Sun and powered off again at the same distance on the outbound side of the orbit.
• For this third solar encounter, the mission team turned on the instruments when the spacecraft was around 0.45 AU from the Sun on the inbound side of its orbit.
• It will turn them off when the spacecraft is about 0.5 AU from the Sun on the outbound side.

TOI 270

• It is the name of the dwarf star and the planetary system recently discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS).
• TOI 270 is about 73 light years away from Earth, and is located in the constellation Pictor.
• Its members include the dwarf star, which is 40 per cent smaller than the Sun in size and mass, and the three planets or exoplanets (planets outside the solar system) that have been named TOI 270 b, TOI 270 c, and TOI 270 d.
• These three planets orbit the star every 3.4 days, 5.7 days, and 11.4 days respectively. In this system, TOI 270 b is the innermost planet.

About Transiting Exoplanet Survey Satellite (TESS)

• TESS is NASA’s latest satellite to search for planets outside our solar system, known as exoplanets.
• The mission will spend the next two years monitoring the nearest and brightest stars for periodic dips in their light.
• TESS is expected to transmit its first series of science data back to Earth in August, and thereafter periodically every 13.5 days, once per orbit, as the spacecraft makes it closest approach to Earth.
• These events, called transits, suggest that a planet may be passing in front of its star.
• TESS is expected to find thousands of planets using this method, some of which could potentially support life.

Tiangong-2

• Tiangong means “Heavenly Palace”. It was 10.4 metres long and 3.35 metres wide at its widest point, and weighed 8.6 metric tonnes.
• It was launched on September 15, 2016 and, in late 2016, hosted two Chinese astronauts for 30 days in what was China’s longest manned space mission so far.
• The recently decommissioned space lab followed the Tiangong-1, China’s first space station, which crashed into the southern Pacific Ocean on April 1, 2018 after Chinese scientists lost control of the spacecraft.
• China had launched Tiangong-1 in 2011 as proof-of-concept of technologies for future stations. The lab was visited by two teams of Chinese astronauts for 11 days and 13 days respectively.

About Hayabusa2

• Japan’s Hayabusa2 spacecraft, which successfully made its second touchdown on asteroid Ryugu has become the first ever space probe to gather material from beneath the surface of an asteroid.
• Launched in December 2014, the probe is a follow-up of Hayabusa, which explored the asteroid Itokawa in 2005.
• Hayabusa was the first mission to return an asteroid sample to Earth.
• The asteroid mission first reached Ryugu — a kilometre-wide asteroid, with a relatively dark surface and almost zero gravity — in June 2018 and made its first touchdown on the surface in February 2019.
• A month later the spacecraft hit the surface of Ryugu with a pellet and created a 10-metre-wide crater.
• It also exposed the materials under the asteroid’s surface that were so far protected from the harsh effects of cosmic rays and charged particles of solar wind blasting through space.

About PUNCH Mission

• NASA has selected an US-based Indian researcher to lead its PUNCH mission which will image the Sun.
• PUNCH stands for “Polarimeter to Unify the Corona and Heliosphere,” is focused on understanding the transition of particles from the Sun’s outer corona to the solar wind that fills interplanetary space.
• It will consist of a constellation of four microsatellites that through continuous 3D deep-field imaging, will observe the corona and heliosphere as elements of a single, connected system.
• This is a landmark mission will image regions beyond the Sun’s outer corona.
• The Sun and the solar wind are one interconnected system, but these have until recently been studied using entirely different technologies and scientific approaches.

Spectrum-Roentgen-Gamma (SRG) Telescope

• The telescope will be launched into space on a Russian-built Proton-M rocket from the Baikonur Cosmodrome in Kazakhstan in June 2019.
• The four-year mission will survey the entire sky eight times and track the evolution of the universe and dark energy, a mysterious repulsive force that is accelerating its expansion.
• Besides, it also aims to detect up to three million supermassive black holes — many of which are unknown — and X-rays from as many as 700,000 stars in the Milky Way.
• The telescope is the first to be sensitive to high-energy ‘hard’ X-rays and map the entire sky.
• The SRG will also find how dark matter — the main engine of galaxy formation — is spread in the universe.
• X-ray sky surveys have also been conducted by previous missions, but they were not able to map the entire sky, the report said.

MeerLICTH Optical Telescope

• Scientists in South Africa have launched the world’s first optical telescope linked to a radio telescope, combining “eyes and ears” to try to unravel the secrets of the universe.
• The latest move combines the new optical telescope MeerLITCH — Dutch for ‘more light’ — with the recently-completed 64-dish MeerKAT radio telescope, located 200 kilometres away.
• This is the eye, with the MeerKAT being the ears as a radio telescope.
• The MeerLITCH uses a main mirror just 65 cm in diameter and a single 100 megapixel detector measuring 10 cm x 10 cm.
• Astronomers have previously had to wait for a cosmic incident to be picked up by a radio telescope and then carry out optic observations afterwards.
• The project has been six years in the making by a joint-team of South African, Dutch and British scientists.

Ultima Thule

• NASA has found evidence for a unique mixture of methanol, water ice, and organic molecules on Ultima Thule’s surface — the farthest world ever explored by mankind.
• Ultima Thule is a contact binary, with two distinctly differently shaped lobes.
• At about 36 kilometres long, it consists of a large, strangely flat lobe — nicknamed “Ultima” — connected to a smaller, somewhat rounder lobe — dubbed “Thule” — at a juncture.
• Officially named (486958) 2014 MU69, it earned the nickname Ultima Thule following a public contest in 2018.
• It is located in the Kuiper Belt, a disc in the outer Solar System (beyond Neptune) that consists of small bodies including Pluto.
• 2014 MU69 was discovered in June 2014 by astronomers using the Hubble Space Telescope but is so distant that many of its characteristics remain to be understood.

About the mission

• New Horizons, a space probe that was launched in 2006, became the first mission to visit Pluto in 2015.
• Travelling farther into the Kuiper Belt, the nuclear-powered space probe has come within 3,500 km of Ultima Thule.
• Images taken revealed that the object may have a shape similar to a bowling pin, or a “snowman”, or a peanut spinning end over end, or could be two objects orbiting each other.
• Flyby data showed that Ultima Thule is spinning like a propeller with the axis pointing approximately toward New Horizons.
• NASA released a composite of two images taken by New Horizons’ high-resolution Long-Range Reconnaissance Imager.

Chang’e-4

• In January, the Chinese spacecraft Chang’e-4 — named after the moon goddess in Chinese mythology — became the first ever craft to touch down on the far side of the lunar surface.
• The team landed its probe in the Von Karmen Crater in the Aitken Basin at the Moon’s south pole — home to one of the largest impact craters known in the solar system.
• Scientists have said they could be a step closer to solving the riddle behind the Moon’s formation, unveiling the most detailed survey yet of the far side of Earth’s satellite.

Cassini Mission

• Launched in 1997, the Cassini mission is a cooperation between NASA, the European Space Agency and the Italian Space Agency.
• It has sent back thousands of stunning images and made numerous discoveries about the ringed planet and its moons.
• Cassini–Huygens is an unmanned spacecraft sent to the planet Saturn.
• Cassini is the fourth space probe to visit Saturn and the first to enter orbit. Its design includes a Saturn orbiter and a lander for the moon Titan.
• The lander, called Huygens, landed on Titan in 2005.

China’s BeiDou navigation satellite, a rival to US GPS, starts global services

• China’s BeiDou Navigation Satellite System (BDS), touted as a rival to the widely-used American GPS, has started providing global services.

BeiDou Navigation Satellite System (BDS)

• Named after the Chinese term for the ‘Big Dipper’, the BeiDou system started serving China in 2000 and the Asia-Pacific region in 2012.
• It will be the fourth global satellite navigation system after the US GPS, Russia’s GLONASS and the European Union’s Galileo.
• The positioning accuracy of the system has reached 10 metres globally and five metres in the Asia-Pacific region.
• Its velocity accuracy is 0.2 metres per second, while its timing accuracy stands at 20 nanoseconds, he said.
• Pakistan has become the first country to use the BeiDou system ending its reliance on the Global Positioning System (GPS).

GRAPES-3 Experiment

• For the first time in the world, researchers at the GRAPES-3 muon telescope facility in Ooty have measured the electrical potential, size and height of a thundercloud that passed overhead on December 1, 2014.
• GRAPES-3 (Gamma Ray Astronomy PeV EnergieS phase-3) is designed to study cosmic rays with an array of air shower detectors and a large area muon detector.
• It aims to probe acceleration of cosmic rays in the following four astrophysical settings.
• It is located at Ooty in India and started as a collaboration of the Tata Institute of Fundamental Research, Mumbai, India and the Osaka City University, Osaka, Japan.

Asteroid ‘99942 Apophis’

• On April 13, 2019, a near-Earth asteroid will cruise by Earth, about 31,000 km above the surface.
• The asteroid, called 99942 Apophis, is 340 m wide.
• At one point, it will travel more than the width of the full Moon within a minute and it will get as bright as the stars in the Little Dipper, according to NASA’s Jet Propulsion Laboratory.
• It is rare for an asteroid this size to pass by Earth so close.
• Although scientists have spotted small asteroids, on the order of 5-10 metres, flying by Earth at a similar distance, asteroids the size of Apophis are far fewer in number and so do not pass this close to Earth as often.
• Among potential lessons from Apophis, scientists are hoping they can use its flyby to learn about an asteroid’s interior.
• Apophis is one of about 2,000 currently known Potentially Hazardous Asteroids, and scientists also hope their observations might help gain important scientific knowledge that could one day be used for planetary defence.

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