Category Astronomy

Are Membrane mirrors for large space-based telescopes?

Researches create lightweight flexible mirrors that can be rolled up during launch and reshaped precisely after deployment.

Mirrors are a significant part of telescopes. When it comes to space telescopes, which have complicated procedures for launching and deploying, the primary mirrors add considerable heft, contributing to packaging difficulties.

Researchers have now come up with a novel way of producing and shaping large, high-quality mirrors. These mirrors are not only thinner than the primary mirrors usually employed in space-based telescopes, but are also flexible enough to be rolled up and stored inside a launch vehicle.

Parabolic membrane mirror

The successful fabrication of such parabolic membrane mirror prototypes up to 30 cm in diameter have been reported in the Optica Publishing Group journal Applied Optics in April. Researchers not only believe that these mirrors could be scaled up to the sizes required in future space telescopes, but have also developed a heat-based method to correct imperfections that will occur during the unfolding process.

Using a chemical vapour deposition process that is commonly used to apply coatings (like the ones that make electronics water-resistant), a parabolic membrane mirror was created for the first time. The mirror was built with the optical qualities required for use in telescopes. A rotating container with a small amount of liquid was added to the inside of a vacuum chamber in order to create the exact shape necessary for a telescope mirror. The liquid forms a perfect parabolic shape onto which a polymer can grow during chemical vapour deposition, forming the mirror base. A reflective metal layer is applied to the top when the polymer is thick enough, and the liquid is then washed away.

Thermal technique

The researchers tested their technique by building a 30-cm-diameter membrane mirror in a vacuum deposition chamber. While the thin and lightweight mirror thus constructed can be folded during the trip to space, it would be nearly impossible to get it into perfect parabolic shape after unpacking. The researchers were able to show that their thermal radiative adaptive shaping method worked well to reshape the membrane mirror.

Future research is aimed at applying more sophisticated adaptive control to find out not only how well the final surface can be shaped, but also how much distortion can be tolerated initially. Additionally, there are also plans to create a metre-sized deposition chamber that would enable studying the surface structure along with packaging unfolding processes for a large-scale primary mirror.

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Which was the first successful soft landing on Mars?

Launched on May 28, 1971, Mars 3 was one among a pair of identical spacecraft. While its lander stopped transmitting data after less than 20 seconds, it nevertheless represents the first successful soft landing on Mars. A.S.Ganesh hands you the details about the Mars 3 mission…

When we talk about the space race between the Cold War adversaries the US. and the Soviet Union, we usually discuss the race to land the first human beings on the moon. Soon after this was achieved, however, attention shifted to our neighbouring planet Mars. The first successful soft landing on Mars was achieved by the Soviet Union with their Mars 3 mission.

At this initial period of planetary exploration, both these space superpowers tended to launch pairs of spacecraft as a precautionary measure. The idea was to have one as the backup. of another, so that at least one of them succeeded in its efforts even if the other failed completely in its objective.

It therefore comes as no surprise that the Mars 2 and Mars 3 missions consisted of identical spacecraft. With a bus/orbiter module and an attached descent/lander module, the combined mass of the spacecraft, with fuel, was approximately 4,650 kg. The Mars 3 spacecraft was 4.1 metres high. 5.9 metres across the two solar panel wings and had a base diameter of 2 metres.

Primary objectives

The primary objective of the Mars 3 orbiter was to image the martian surface and clouds. determine the temperature on Mars, and measure properties of the martian atmosphere. among others. These were in addition to serving as a communications relay to send signals from the lander to Earth.

Mars 3 was launched on May 28, 1971, just nine days after Mars 2 had been successfully launched. Ten days later, on June 8, a mid-course correction was made after which Mars 3 was involved in a three-way race with Mars 2 and U.S.’ Mariner 9 to become the first spacecraft to orbit Mars.

Even though Mariner 9 was last off the blocks, having been launched on May 30, it became the first to reach Mars on November 14. Mars 2 reached Mars on November 27 and Mars 3 made it to its destination on December 2.

Achieves soft landing

 Less than five hours before reaching Mars, the descent module of Mars 3 had been released. Having entered the martian atmosphere at roughly 5.7 km/s, a combination of aerodynamic braking, parachutes, and retro-rockets allowed the lander to achieve a soft landing. With the Mars 2 lander having crashed, this made the Mars 3 mission the first ever to achieve a soft landing on Mars.

Only just though, as the lander stopped transmitting and the instruments stopped working less than 20 seconds after the successful landing. While the reasons remain unknown, the massive surface dust storms that were raging at the time of landing could have caused the lander to stop working.

As the orbiter had suffered a partial loss of fuel, it couldn’t put itself into the planned 25 hour orbit. Instead, a truncated burn was performed by the engine in order to put the spacecraft into a 12 day, 19 hour long orbit about Mars.

20 orbits around Mars

A large volume of data was sent hack by Mars 2 and Mars 3 orbiters from December 1971 to March 1972, even though transmission continued till August. On August 22, 1972, an announcement was made stating that Mars 2 and Mars 3 had completed their missions. While Mars 2 had completed 362 orbits of the red planet, Mars 3 had performed 20 orbits.

Apart from the 60 images received from the probes, the data provided by them revealed mountains as high as 22 km, atomic hydrogen and oxygen in the upper atmosphere, and surface temperatures and pressures. The data gathered not only provided information on the martian gravity and magnetic fields, but also helped create surface relief maps.

Mars 3 was back in the news four decades later in April 2013 when citizen enthusiasts found features of its hardware in a five-year-old image from NASA’s Mars Reconnaissance Orbiter. The debris in the images resembled what might have been the parachute, heat shield, terminal retrorocket and lander. Regardless of whether these were the debris of the Mars 3 lander or not, the mission did successfully become the first ever to achieve a soft landing on our neighbouring red planet.

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What are the Astronomers, who helped enhance our understanding of the cosmos?

We have always been looking up, peering into the sky, trying to find answers to the many questions about the universe. Many astronomers have tried to unravel the mysteries of the universe. From believing that Earth was flat and the planets revolved around it, we have come a long way. Let’s take a look at some of history’s greatest astronomers who helped enhance our understanding of the Cosmos.

From believing that the Earth was flat and the planets revolved around it, we have come a long way.Some 2000 years ago, when it was widely believed that the world was flat, Greek mathematician and astronomer Eratosthenes (276 BC-194 BC) calculated the Earth’s circumference. In those days, the very act of coming up with scientific thoughts which were at odds with the ones in existence was not encouraged. The theory that the Earth revolved around the Sun was itself considered heretical by the religious and after a trial, Italian astronomer Galileo Galilei was kept under house arrest until his death. Polish astronomer Nicolaus Copernicus didn’t publish his magnum opus “De revolutions orbium coelestium” (On the Revolutions of the Heavenly Spheres) until he was on his deathbed. Let’s take a look at some of history’s greatest astronomers who threw new light on the cosmos.

CLAUDIUS PTOLEMY (AD 100-AD 170)

 Astronomer and mathematician Claudius Ptolemy authored several scientific teas and is noted for his Ptolemaic system. It was a geocentric (Earth-centred) model of the universe, where the sun, stars, and other planets revolved around Earth. This model was used for a long period, for over 1200 years, until the heliocentric view of the solar system was established. Although his model of the universe was wrong, his work and the scientific texts he authored helped astronomers make predictions of planetary positions and solar and lunar eclipses. “The Almagest, a comprehensive treatise on the movements of the stars and planets, was published in the 2nd Century. It is divided into 13 books. This manual served as the basic guide for Islamic and European astronomers. He also catalogued 48 constellations. 

NICOLAUS COPERNICUS (1473-1543)

 Nicolaus Copernicus changed the way scientists viewed the solar system. Back in the 16th Century, he came up with a model of the solar system where the Earth revolved around the Sun: it was the revolutionary heliocentric model. He removed Earth from the centre of the universe and replaced it with the Sun! He also didn’t believe in the Ptolemaic model of the planets travelling in circular orbits around the Earth. He also explained the retrograde motion of the planets (retrograde motion is when planets appear to move in the opposite direction of the stars). When the Polish astronomer was 70, he published his book “De Revolutions Orbium Coelestium” (“On the Revolutions of the Heavenly Spheres”), on his deathbed. It took over a century for his idea to gain credence.

GALILEO GALILEI (1564-1642)

Optical astronomy began with Galileo Galilei. Born in Italy, Galilei is credited with creating the optical telescope. In fact, what he did was improve upon the existing models. He came up with his first telescope in 1609, modelling it after the telescopes produced in other parts of Europe. But here is the catch. Those telescopes could magnify objects only three times. Galileo came up with a telescope that could magnify objects 20 times. He then pointed it towards the sky, coming up with the greatest discoveries ever. He discovered the four primary moons of Jupiter which are referred to as the Galilean moons. He also discovered the rings of Saturn. Even though the theory of Earth circling the Sun had been around since Copernicus’ time, when Galileo defended it, he was kept under house arrest till the end of his lifetime.

JOHANNES KEPLER (1571-1630)

Danish astronomer Johannes Kepler modified the Copernican view of the solar system and changed it radically. He deduced that the planets travelled in elliptical orbits, one of the most revolutionary ideas at the time, replacing Copernicus view that they travelled in circular objects. He came up with three revolutionary laws involving the motions of planets these three laws make him a towering figure in astronomy. Kepler also observed a supernova in 1604. It is now called Kepler’s Nova.

EDMOND HALLEY (1656-1742)

“Halley’s comet is perhaps a term you would have heard quite often. English astronomer Edmond Halley never saw the comet named after him. Officially called 1P/Halley, Halley’s  comet  is a periodic comet that passes by the Earth once every 76 years (roughly). This famed comet will return in 2061. It was Halley’s mathematical prediction of the comet’s return that made him a towering figure among the list of astronomers. He said that the comet that appeared in 1456, 1531, 1607, and 1682 were all the same and that it would return in 1758. Halley was never around to witness this, but the world saw the comet and its return. The comet was later named in his honour. One of the earliest catalogues of the southern sky was also produced by Halley. In 1676, he sailed to the island St. Helena, South Atlantic Ocean. There he spent a year measuring the position of stars and came up with the first catalogue of the southern sky! Seen here is a painting of the astronomer. 

WILLIAM HERSCHEL (1750-1848)

Musician-tumed astronomer William Herschel started exploring the skies with his sister Caroline quite late in his career but eventually, he compiled a catalogue of 2.500 celestial objects The German astronomer discoverest the planet Uranus and several moons of other planets it was during his mid 30s that he startet looking up and exploring the cosmos In 1759. Herschel left Germany and moved to England where he started teaching music When Herschels interest in astronomy grew, rented a telescope. He then went ahead and built himself a large telescope to watch the celestial bodies. His sister Caroline assisted him until Herschel’s death and also became the first woman to discover a comet. She eventually discovered eight of them. When Herschel found a small object in the night sky, he explored further and found out that it was a planet. The Uranus was thus discovered. He was knighted by the monarch after the discovery and was appointed the court astronomer. Following this he gave up his music career and devoted himself to the skies. He found the moons of Uranus and Saturn Craters on the moon. Mars and Mimas (Saturn’s moon) are named after the astronomer.

ANNIE JUMP CANNON (1863-1941)

Known as the “census taker of the sky, American astronomer Annie Jump Cannon made stellar contributions to the field of astronomy. She classified around 3,50,000  stars manually. At a time when gender representation in astronomy was  skewed. Cannon with her impeccable contributions inspired many women to pursue astronomy. During that time, stars were classified alphabetically, from A to Q. based on their temperatures. She built a new classification system with ten categories and forever changed the way scientists classified stars by developing the Harvard system which is in use even today.

CARL SAGAN (1934-1996)

American astronomer Carl Sagan was not just a science poster boy but he was one of the most influential voices in the scientific  realm  who  made the cosmos a subject of interest for the masses. Sagan played a huge role in in the American space program. He popularised astronomy and through his talks and books motivated many to become sky watchers. He also founded the Planetary Society, a non-profit that is focussed on advancing space science and exploration. He was a professor of astronomy and space sciences and director of the Laboratory for Planetary Studies at Cornell University. His contributions include explaining the high temperatures of Venus and the seasonal changes on Mars. His book “Cosmos” is a bestseller that was also turned into a television show (hosted by Sagan) which was watched by a billion people in 60 countries. He also wrote a science fiction novel “Contact” which was adapted to the screen.

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What is SWOT?

The satellite has been designed to conduct a landmark survey of the world’s oceans, lakes, and rivers from space for the first time.

NASA, the U.S. space agency, recently launched a satellite called SWOT. What is its objective and how will it help us? Let’s find out.

Its mission

SWOT, short for the Surface Water and Ocean Topography satellite, was recently launched from California to make a comprehensive survey of the world’s oceans, rivers, and lakes from space for the very first time. Dubbed a “revolution in hydrology”, SWOT, an SUV-sized satellite flying at a height of 890 km, will offer an unprecedented, clear view of the water bodies, while tracking the rise in sea levels, as well as rivers, lakes, and reservoirs. The satellite is expected to offer key insights into how these bodies of water influence climate change and factors such as how much more heat and carbon dioxide oceans can absorb. Oceans are estimated to have absorbed more than 90% of the excess heat trapped in Earth’s atmosphere caused by human-induced greenhouse gas emissions. With climate change accelerating, some regions are experiencing extreme droughts. while others extreme floods, along with changing precipitation patterns. According to researchers, the observations of SWOT will improve our understanding of how water moves around Earth, its circular currents in oceans, etc. This will help predict floods in areas where there is too much water, and manage water in places that are prone to drought.

How will it work?

The global water survey satellite will measure the height of water in freshwater bodies and the ocean on more than 90% of Earth’s surface – which it will track at least once every 21 days. Researchers will be able to get data on millions of lakes, rather than the few thousands currently visible from space. The technology employed by SWOT is called KaRin, a Ka-band radar interferometer. The radar sends down a signal which is reflected back by the water surface. This echo is received by two antennas, resulting in two sets of data providing high accuracy for water detection and resolution. The data, compiled from the radar sweeps of the planet, will be used to bolster weather and climate forecasts and aid in managing scarce freshwater supplies in drought-stricken areas.

Who developed it?

The satellite is a billion-dollar project developed jointly by NASA and France’s space agency CNES, with contributions from the Canadian space agency and the U.K. space agency. It was carried onboard a spacex Falcon-9 rocket from the Vandenberg U.S. Space Force Base. SWOT will start collecting scientific data in about six months time after undergoing checks and calibrations. The satellite’s components were built primarily by NASA’s Jet Propulsion Laboratory near Los Angeles and CNES.

According to SWOT’S project head at CNES, Thierry Lafon, the mission is meant to last for three-and-a-half years, but could be extended. The U.S. and French space agencies have worked together in the field for over three decades. An earlier satellite developed by the two agencies, TOPEX/Poseidon, improved understanding of ocean circulation and its effect on global climate. It also aided the forecast of the 1997-1998 El Nino weather phenomenon.

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What is the significance of Artemis Accord for India?

India’s aspirations in the outer space and acceptance of the Artemis Accords have affirmed the country’s interest in building a greater relationship with the National Aeronautics and Space Administration (NASA) and its partners. As the space community lauds India’s acceptance of the Artemis Accords, let us know more about it.

Artemis Accords

The Artemis Accords are part of the Artemis programme, which is a mega-initiative by NASA with the aim to land the first woman and first person of colour on the Moon, make new scientific discoveries, and explore more of the lunar surface. Artemis is the name of the goddess of the Moon in Greek mythology and also the twin sister of Apollo.

The Artemis Accords were established in 2020 by NASA, the U.S., and seven other founding member nations – Australia, Canada, Italy, Japan, Luxembourg, UAE, and the U.K. This June 21, India became the 27th country to sign the Artemis Accords.

The Artemis Accords are a set of non-binding guidelines designed to guide civil space exploration and use in the 21st Century. It is a NASA-led effort to return humans to the moon by 2025, with the ultimate goal of expanding space exploration to Mars and beyond.

The Artemis Accords reinforce and implement key obligations in the 1967 Outer Space Treaty (which provided the basic framework for international space law). The accords also affirm the importance of the Rescue and Return Agreement opened in 1968, which emphasises the responsibility of nations to safely return astronauts and equipment to Earth.

Besides, the accords emphasise the need to preserve historically significant human or robotics landing sites, artefacts, spacecraft, and other evidence of activity on celestial bodies.

Outer Space Treaty

The Outer Space Treaty is an international treaty binding the parties to use outer space only for peaceful purposes. The treaty was enforced on October 10, 1967, after being ratified by the U.S., then Soviet Union, the U.K.. and several other countries.

The treaty prohibits countries from placing nuclear arms or other weapons of mass destruction in orbit, on the Moon, or on other bodies in space. Also, no country can claim sovereignty over the Moon or other celestial bodies. The countries are liable for any damage caused by objects launched into space from their territory.

India and the Artemis Accords

India’s Indian Space Research Organisation (ISRO) and NASA had been working together in several lunar missions. However, the cooperation was limited to sharing knowledge. With the signing of the Accords, India and the US will share data, technology, and resources, and work together in ensuring the safety and sustainability of exploring the Moon.

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What is the history of heroes?

In the hindi movie Three Idiots, remade in tamil as nanban, a character remarks that the world only remembers those who come first. He says nobody knows the name of the second person to land on the moon, because he is not important. This cannot be farther from the truth. In fact, the person who landed second on the moon in the celebrated hero and, in some accounts, a controversial figure. Interestingly, he was the first person to do something unique in space. Can you name him?

Answer. “Buzz” Aldrin third from left in the above picture, is an American hero, who has made three spacewalks. A Presbyterian elder (elected member of the crurch), Aldrin was the first person to hold a religious ceremony on the moon when he privately took communion. Before he headed into space in 1969, He got special permission to take bread and wine with him to space and give himself communion. He has been accorded numerous honours, including the presidential Medal of Freedom in 1969. Rumours were rife in 2020 that buzz had reported to NASA that he saw aliens on his way to the moon. It was later proven to be false.

In the 1950s, when racial segregation of white and black communities was the norm in the U.S., it was illegal for a black person to sit next to a white person. If a white person had no seat, black passengers had to vacate their seat and offer it. In 1955, one lone black woman passenger refused to abide by this irrational norm. She refused to stand up and offer her seat to a white person, triggering a massive protest that culminated in the U.S. civil rights movement. Can you name this person?

Answer: Rosa Parks was an American civil rights activist who played a crucial role in the Montgomery bus boycott movement. Her actions inspired the local black community in Alabama to organise the movement, which was led by a young Dr. Martin Luther King Jr. Though Parks lost her job as a consequence of her dissent, the U.S. Supreme Court, finally, ruled that bus segregation was unconstitutional. In 1999, Parks was awarded the Congressional Gold Medal, the highest honour the United States bestows on a civilian. Dr. King, of course, went on to become an American hero.

He was nicknamed “Africa’s Che Guevara” for his stance on the West and his fierce anti-colonialist ideology. A military leader, he changed his country’s name from the colonial Upper Volta to Burkina Faso – “the land of honest men”. He initiated several progressive reforms in his country, from promoting vaccinations for babies to banning the horrendous practice of female genital mutilation, and improving access to education. Can you name him?

Answer: Thomas Sankara was a Marxist leader who came to power in 1983 following a leftist coup that overthrew the moderate military faction ruling Burkina Faso. Much like Che Guevara, this frugal-living, motorcycle-riding, guitar-playing leader became a symbol of hope and resistance throughout Africa.

Once, when a reporter asked him why he did not want his pictures hung in public places, he famously said, “because there are seven million Thomas Sankaras here”. A proponent of Pan-Africanism, he was murdered just within four years of coming to power. Sankarism, currently, is a popular political trend in Africa. They believe his murder was orchestrated by imperialist forces.

Bangabandhu, as he is fondly referred to, was a revolutionary who fought for the liberation of East Pakistan. He was the founder of Bangladesh and served as its President and Prime Minister until he and his family were assassinated in 1975. Only two of his daughters, who were abroad at the time, escaped the attack. One of them, Sheikh Hasina, is currently the Prime Minister of Bangladesh. Can you name this leader?

Answer: Sheikh Mujibur Rahman was a socialist revolutionary who was among the leaders of the freedom movement in Bangladesh. Though the leader of a Muslim majority country, Mujib, as he was known among his friends and followers, aspired to build a sovereign and secular country. “First I am a human being, then a Bengali, and after that a Muslim,” he had once famously remarked. Mujib admired Nobel Laureate Rabindranath Tagore’s view that humanism is always greater than nationalism. Many believe his assassination to be linked with his progressive push to develop Bangladesh as a liberal nation. With the assassination of Mujib, Bangladesh slipped into political regression. Secular values of the State degraded gradually and Islam was declared as the State religion in 1988. Persecution of religious minorities became rampant.

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