My Science School

The white dwarf consists of an exotic stew of helium, carbon, and oxygen nuclei swimming in a sea of highly energetic electrons. The combined pressure of the electrons holds up the white dwarf, preventing further collapse towards an even stranger entity like a neutron star or black hole.

The white dwarf now has before it a long, quiet future. As the trapped heat trickles out, it slowly cools and dims. Eventually it will become an inert lump of carbon and oxygen floating invisibly in space: a black dwarf. But the universe isn’t old enough for any black dwarfs to have formed. The first white dwarfs born in the earliest generations of stars are still, 14 billion years later, cooling off. The coolest white dwarfs we know of, with temperature around 4,000 degrees Celsius (7,000 degrees Fahrenheit), may also be some of the oldest relics in the cosmos.

But not all white dwarfs go quietly into the night. White dwarfs that orbit other stars lead to highly explosive phenomena. The white dwarf starts things off by siphoning gas off its companion. Hydrogen is transferred across a gaseous bridge and spilled onto the white dwarf’s surface. As the hydrogen accumulates, its temperature and density reach a flash point where the entire shell of newly acquired fuel violently fuses releasing a tremendous amount of energy. This flash, called a nova, causes the white dwarf to briefly flare with the brilliance of 50,000 suns and then slowly fade back into obscurity.

White dwarfs – the cores left behind after a star has exhausted its fuel supply – are sprinkled throughout every galaxy. Like a stellar graveyard, they are the tombstones of nearly every star that lived and died. Once the sites of stellar furnaces where new atoms were forged, these ancient stars have been repurposed as an astronomer’s tool that have upended our understanding of the evolution of the universe.

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The first woman to travel into space was a Soviet cosmonaut named Valentina Tereshkova. She traveled around Earth 48 times while orbiting in the Vostok 6 spacecraft in 1963. The first American woman to travel into space was Sally Ride who rode onboard the space shuttle Challenger in 1983 and 1984.

Born in the village of Maslennikovo northeast of Moscow, Tereshkova volunteered for the Soviet cosmonaut program after Yuri Gagarin made history as the first man to fly in space on April 12, 1961. She was not a pilot, but had extensive parachuting experience, with 126 jumps under her belt. (Gagarin parachuted to Earth, ejecting from the Vostok capsule during descent as part of the landing sequence.)

Tereshkova was one of four women who received 18 months of training for Vostok 6, and was ultimately selected to pilot the flight. The mission launched from Baikonur Cosmodrome two days after Vostok 5, piloted by cosmonaut Valeriy Bykovsky, with the two spacecraft's coming within 3 miles (5 kilometers) of each other. 

Tereshkova spent 70 hours in space and orbited Earth 48 times during her mission. Though an icon of Soviet space exploration, she never flew in space again and became a test pilot and instructor.

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Yuri Gagarin was the first person to fly in space. His flight, on April 12, 1961, lasted 108 minutes as he circled the Earth for a little more than one orbit in the Soviet Union's Vostok spacecraft. Following the flight, Gagarin became a cultural hero in the Soviet Union. Even today, more than six decades after the historic flight, Gagarin is widely celebrated in Russian space museums, with numerous artifacts, busts and statues displayed in his honor. His remains are buried at the Kremlin in Moscow, and part of his spacecraft is on display at the RKK Energiya museum.

Gagarin's flight came at a time when the United States and the Soviet Union were competing for technological supremacy in space. The Soviet Union had already sent the first artificial satellite, called Sputnik, into space in October 1957.

Before Gagarin's mission, the Soviets sent a test flight into space using a prototype of the Vostok spacecraft. During this flight, they sent a life-size dummy called Ivan Ivanovich and a dog named Zvezdochka into space. After the test flight, the Soviet's considered the vessel fit to take a human into space.

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The Imaging Infrared Spectrometer (IIRS) instrument onboard the Chandrayaan-2 lunar orbiter has confirmed the presence of both hydroxyl ions (OH) and water molecules (H2O) on the surface of the moon.

It has further quantified the amount of water molecules present on the lunar surface regions it imaged, and distinguished parts of the moon that are water-rich from those that are scant in hydration.

Researchers used the data obtained by the Chandrayaan-2 orbiter's imaging infrared spectrometer (IIRS), an instrument that collects information from the Moon's electromagnetic spectrum, to understand the mineral composition of the satellite. They analysed data from three strips on the Chandrayaan-2 IIRS sensor for hydration, which led to "unambiguous detection of OH (hydroxyl) and H2O (water) signatures."

The research findings, published in the journal Current Science, state that hydration absorption was observed at all latitudes and surface types in varying degrees. "The initial data analysis from IIRS clearly demonstrates the presence of widespread lunar hydration and unambiguous detection of OH and H2O signatures on the Moon between 29 degrees north and 62 degrees north latitude," researchers said.

It was also observed from the data that the brighter sunlit highland regions at higher latitudes of the Moon were found to have higher hydroxyl or possibly water molecules. Scientists at the Indian Institute of Remote Sensing (IIRS) in Dehradun opine that the formation of hydroxyl and water on the Moon is due to space weathering, a process of interaction of solar winds with the lunar surface. This combined with impact events lead to chemical changes that further triggered the formation of reactive hydroxyl molecules.

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Mars' moons are among the smallest in the solar system. Phobos is a bit larger than Deimos, and orbits only 3,700 miles (6,000 kilometers) above the Martian surface. No known moon orbits closer to its planet. It whips around Mars three times a day, while the more distant Deimos takes 30 hours for each orbit. Phobos is gradually spiraling inward, drawing about six feet (1.8 meters) closer to the planet each century. Within 50 million years, it will either crash into Mars or break up and form a ring around the planet.

To someone standing on the Mars-facing side of Phobos, Mars would take up a large part of the sky. And people may one day do just that. Scientists have discussed the possibility of using one of the Martian moons as a base from which astronauts could observe the Red Planet and launch robots to its surface, while shielded by miles of rock from cosmic rays and solar radiation for nearly two-thirds of every orbit.

Like Earth's Moon, Phobos and Deimos always present the same face to their planet. Both are lumpy, heavily-cratered and covered in dust and loose rocks. They are among the darker objects in the solar system. The moons appear to be made of carbon-rich rock mixed with ice and may be captured asteroids.

Phobos has only 1/1,000th as much gravitational pull as Earth. A 150-pound (68 kilogram) person would weigh two ounces (68 grams) there. Yet NASA's Mars Global Surveyor has shown evidence of landslides, and of boulders and dust that fell back down to the surface after being blasted off the moon by meteorites.

Credit : NASA Science 

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Even though Mercury is the closest planet to the Sun, Venus is the hottest planet in our solar system. This is because Mercury has almost no atmosphere, while Venus has a very thick atmosphere. This causes all the heat to be radiated back into space on Mercury. However, the heat is trapped on Venus, with the average temperature being 462°C.

The degree of hotness of a planet does not depend on as much on closeness to the Sun as on its atmosphere. Carbon dioxide has the tendency to absorb heat which in turn increases the temperature.

Mercury's atmosphere does not contain carbon dioxide (because of which all the heat is returned to space). Venus contains a high percentage of carbon dioxide due to which it is hottest planet.

In ancient times, Venus was often thought to be two different stars, the evening star and the morning star — that is, the ones that first appeared at sunset and sunrise. In Latin, they were respectively known as Vesper and Lucifer. In Christian times, Lucifer, or "light-bringer," became known as the name of Satan before his fall. However, further observations of Venus in the space age show a very hellish environment. This makes Venus a very difficult planet to observe from up close, because spacecraft do not survive long on its surface.

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Planet Mercury actually has no moons. Up first are Mercury and Venus. Neither of them has a moon.

Because Mercury is so close to the Sun and its gravity, it wouldn’t be able to hold on to its own moon. Any moon would most likely crash into Mercury or maybe go into orbit around the Sun and eventually get pulled into it.

If moons are such a common feature in the Solar System, why is it that Mercury has none? Yes, if one were to ask how many satellites the planet closest to our Sun has, that would be the short answer. But answering it more thoroughly requires that we examine the process through which other planets acquired their moons, and seeing how these apply (or fail to apply) to Mercury.

To break it all down, there are three ways in which a body can acquire a natural satellite. These causes have been determined thanks to many decades of astronomers and physicists studying the various moons of the Solar System, and learning about their orbits and compositions. As a result, our scientists have a good idea of where these satellites came from and how they came to orbit their respective planets.

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Mercury, Latin Mercurius, in Roman religion, god of shopkeepers and merchants, travelers and transporters of goods, and thieves and tricksters. He is commonly identified with the Greek Hermes, the fleet-footed messenger of the gods.

The cult of Mercury is ancient, and tradition has it that his temple on the Aventine Hill in Rome was dedicated in 495 BCE. There Mercury was associated with Maia, who became identified as his mother through her association with the Greek Maia, one of the Pleiades, who was the mother of Hermes by Zeus; likewise, because of that Greek connection, Mercury was considered the son of Jupiter. Both Mercury and Maia were honoured in the Mercuralia festival on May 15, the dedication day of Mercury’s temple on the Aventine.

Mercury is sometimes represented as holding a purse, symbolic of his business functions. Artists, like followers of Roman religion themselves, freely borrowed the attributes of Hermes and portrayed Mercury also wearing winged sandals or a winged cap and carrying a caduceus (staff).

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All of the planets in our Solar System have had a lot of craters. This was especially true in the past when there were many more asteroids traveling in our solar system than there are today. On planets like Venus, Earth, and Mars, we do not see as many craters because most of them have been eroded away by wind, rain, volcanic activity, and other forces. On the giant gas planets, Jupiter, Saturn, Uranus, and Neptune, we do not see any craters because there is no visible solid surface for the meteors to hit. On Mercury, where there is no atmosphere, there is no weather to erode away the craters, so most of the craters are still visible.

Craters are the most widespread landforms in the solar system. Craters are found on all of the terrestrial planets—Mercury, Venus, Earth and Mars. The surfaces of asteroids and the rocky, ice covered moons of the outer gas planets are cratered as well. The craters left by impacting objects can reveal information about the age of a planet's surface and the nature and composition of the planet's surface at the time the crater was formed.

Impact craters dominate the surfaces of Mercury and the Earth's Moon. Both bodies lack liquid water on their surfaces that would erode impact craters over time. They also lack an atmosphere which, on planets like the Earth and Venus, could disintegrate meteoroids before they impact the surface. However, old craters can be eroded by new impact events. Mercury and the Moon have very old surfaces. One of the youngest large craters on the Moon is Tycho, which was formed about 109 million years ago.

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The smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth's Moon.

From the surface of Mercury, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight would be as much as seven times brighter. Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system – that title belongs to nearby Venus, thanks to its dense atmosphere.

Because of Mercury's elliptical – egg-shaped – orbit, and sluggish rotation, the Sun appears to rise briefly, set, and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset.

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Dr Swati Mohan was the first to confirm that the rover had successfully touched down on the Martian surface after surviving a particularly tricky plunge through the atmosphere of the Red Planet.

“Touchdown confirmed! Perseverance safely on the surface of Mars, ready to begin seeking signs of past life,” flight controller Swati Mohan announced as US made the historic landing on Mars, prompting her colleagues at Nasa fist-bump and break into celebrations.

The National Aeronautics and Space Administration's (NASA) Perseverance rover successfully touched down on the surface of Mars after surviving a blazing seven-minute plunge through the Martian atmosphere.

Swati Mohan has been associated with the Perseverance Mars mission since its inception and has been working on the project for over seven years. She has also worked on Nasa’s Cassini mission to the Saturn.

As the world watched Perseverance make a dramatic and difficult landing on the Martian surface, Swati Mohan steered through the operations in her calm and composed self. The bindi-clad Swati Mohan communicated and coordinating between the GN&C subsystem and others teams of the milestone project.

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Sunita Williams is an Indian American astronaut and US Navy officer, who formerly held the record for the most space walks (7) and the most space walk time for a woman at 50 hrs and 40 minutes.

She was also assigned to the International Space Station as a member of Expeditions 14 & 15. In 2012 she served as the flight engineer of Expedition 32 and then Commander of Expedition. In 2007, she ran the first marathon by a person orbit. She finished the Boston Marathon in 4 hours and 24 minutes.

She was born in Ohio and graduated from US Naval Academy with a bachelors degree in Physical Science. Sunita obtained her Master’s degree in Engineering Management from Florida Institute of Technology.
She lives in Texas with her husband.

Credit : National Indo-American Museum 

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Kalpana Chawla spent her whole life chasing her dreams of being an astronaut. In 1997, she made history as the first woman of Indian origin to go to Space. Kalpana Chawla created opportunities, shattered glass ceilings, and spearheaded groundbreaking research for NASA.

It’s the 1960s, and it’s uncommon for women and girls in Karnal, India to receive an education. But from her earliest years, Kalpana Chawla shows an obsession with flying and space. Her mother advocates for her to go to school, and she excels.

The youngest of four children, Kalpana is an all-star student, committed to academics–science particular–above all else. She finishes high school then studies aeronautics at Punjab Engineering college. When she can’t advance any further in India’s education system, she emigrates to the US, knowing she’ll stop at nothing to become an astronaut.

It’s 1981, Kalpana is 20 years old and new to America. She earns her Master’s Degree in Texas, then her Doctorate in Colorado, and by the time she’s 26, she’s recruited to NASA as a research scientist.  3 years later, Kalpana naturalizes as a US citizen so she can apply to the NASA Astronaut Corps.

While training in the rigorous space mission program, Kalpana remains committed to education and creating opportunities. Kalpana starts a program providing two students from her former school in India with a visit to NASA each year. Meanwhile, her research is published in technical journals and increasingly cited in conference publications. Kalpana becomes increasingly vital to the aeronautical field and by the time she’s 32 years old, Kalpana has completed her training and is selected for her first flight.

Kalpana Chawla goes to space in December 1997, the first Indian-born woman to do so. While on a 15-day mission, orbiting the earth 252 times, Kalpana records videos documenting her work. She describes, “every once in a while, city lights peep through the clouds. It’s very much like a storybook.”

Upon return to Earth, Kalpana is one of seven people selected for another mission: the STS-107 on the Columbia Space Shuttle. they launch in early 2003, and Kalpana and the crew conduct 80 experiments over 16 days. After a successful mission, the shuttle returns to Earth on a February morning, set to land at the Kennedy Space Center. But just moments before landing in Texas, the shuttle malfunctions and breaks apart. All seven crew members–Kalpana Chawla, William McCool, Laurel Clark, David Brown, Ilan Ramon (the first Israeli astronaut), Michael P. Anderson, and Rick Husband–are tragically killed in the accident. Kalpana is 41 years old.

Over the course of Kalpana Chawla’s two missions, she logged 30 days, 14 hours, and 54 minutes in space. After her death, Kalpana Chawla was award the Congressional Medal of Honor for her history-shaping contributions to the field of aeronautics. Today, there are university buildings, scholarship funds, and even a NASA supercomputer named after her.

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Rakesh Sharma, Indian military pilot and cosmonaut, the first Indian citizen in space.

In 1970 Sharma joined the Indian Air Force as a pilot. He flew 21 combat missions in a MiG-21 in the Bangladesh war of 1971. In 1982 he was selected as a cosmonaut for a joint Soviet-Indian spaceflight. On April 3, 1984, he flew on board Soyuz T-11 with two Soviet cosmonauts, commander Yury Malyshev and flight engineer Gennady Strekalov, to the space station Salyut 7. There Sharma performed experiments that included photography of India from space and exercises to study the effects of yoga on the body during weightlessness. The mission lasted nearly eight days, and Sharma and his crewmates landed in Kazakhstan on April 11. In 1987 he joined the Indian company Hindustan Aeronautics as its chief test pilot. He left Hindustan Aeronautics in 2001 and became chairman of the board of Automated Workflow, a process-management company based in Bangalore (Bengaluru).

One of the most memorable experiences of the first India reaching space in 1984 was Sharma’s conversation with then-Prime Minister Indira Gandhi who asked how India looked from up there. To this, Sharma replied, "Saare Jahaan Se Achcha" before adding that the most beautiful moments from space were sunrises and sunsets. Further, apart from being the first Indian to stay in space, Sharma is also the first Indian to receive the honour of the ‘Hero of Soviet Union’ award. He also received Ashok Chakra along with his Russian co astronauts.

Credit : Britannica 

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Sirisha Bandla, a 34-year-old aeronautical engineer, is set to become the third Indian-origin woman to head to space when she flies as part of Virgin Galactic's first fully crewed flight test on Sunday.

Bandla, who was born in Guntur district in Andhra Pradesh and brought up in Houston, Texas, will join Sir Richard Branson, the company's billionaire founder, and five others on board Virgin Galactic's SpaceShipTwo Unity to make a journey to the edge of space from New Mexico.

Bandla, a Purdue University alumna, will be evaluating the human-tended research experience, using an experiment from the University of Florida that requires several handheld fixation tubes that will be activated at various points in the flight profile, a statement on the Galactic website said.

 Bandla started in her role as the Vice President of Government Affairs and Research Operations at Virgin Galactic in January 2021, the university said in a statement.

Bandla grew up in Houston, near NASA's Johnson Space Center, and always wanted to become an astronaut. But poor eyesight meant she could not meet the requirements to become a pilot or an astronaut, derailing her high-school plan to go the Air Force-to-NASA route, she said in the statement.

Credit : The Economic Times 

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