My Science School

A white dwarf that has been discovered recently is the smallest known example. At just a little over the size of our moon, this white dwarf named 27 31901 1458, packs 1.3 times the mass of our sun making it at the same time among the most massive white dwarfs ever known.

What are white dwarfs?

White dwarfs are the remnants left behind when some stars nun out of their nuclear fuel. Close to the end of its nuclear burning stage, this type of star expels the majority of its outer material.The only part of the star remaining, its hot core, is what is referred to as a white dwarf.

While white dwarfs are usually closer to the size of the Earth (radius around 6,300 km), this one has a radius of just 2.100 km, nearer to our moon's radius of around 1.700 km. Even though we are used to seeing bigger objects in our daily lives being more massive than their smaller counterparts, in the case of white dwarfs, it is quite the opposite. This means that white dwarfs shrink in size as they gain more mass. Therefore, even though it might sound counter-intuitive this white dwarf that is so small is actually among the most massive.

Rotates rapidly

Apart from the fact that this white dwarf is the smallest and super massive, it is also rotating rapidly. It spins around once in roughly seven minutes and has a powerful magnetic field that is over a billion times stronger than that of our Earth's

The scientists who discovered this white dwarf did it using the Zwicky Transient Facility that is part of the Palomar Observatory in California. The ZTF in the white dwarfs name, as you might have rightly guessed, comes from the name of the facility.

If this white dwarf had been more massive than it is, it wouldn't have been able to support its own weight and would have exploded While scientists can't yet say for certain, they believe that this certain white star probably formed due to the merger of two white dwarfs Scientists have plenty to learn from white dwarfs and this newly discovered, small one would also contribute in its own way.

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Yang Liwei, (born June 21, 1965, Suizhong, Liaoning, China), Chinese astronaut and the first person sent into space by the Chinese space program.

Yang was identified as the crew member for China’s first crewed spaceflight only one day before the scheduled launch of the Shenzhou 5 craft. On October 15, 2003, he lifted off from the Jiuquan Satellite Launch Centre in the Gobi desert in China’s Gansu province. A Chang Zheng 2F rocket boosted Shenzhou 5 into space, where Yang spent 21 hours and orbited Earth 14 times.

He never entered the craft’s orbital module, which was released to perform a six-month military imaging reconnaissance mission. On October 16 he returned aboard the reentry module, which parachuted to the ground near a landing site in Inner Mongolia.

Following Yang’s return, he was named vice-commander-in-chief of the astronauts system of China’s crewed spaceflight project. In 2008 Yang was promoted to major general.

Credit : Britannica

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Chang'e 4 is a robotic spacecraft mission, part of the second phase of the Chinese Lunar Exploration Program. China achieved humanity's first soft landing on the far side of the Moon, on 3 January 2019

The launch mass of Chang’e-4 spacecraft is about 3,780 kg. The mass of lander is about 1,200 kg and that of rover is 140 kg. As per the mission design, the rover is expected to explore the lunar surface for a period of three months while the lander’s mission would last for a full year. The lander has released a rover, called Yutu-2 (Jade Rabbit) for performing experiments in the Von Karman Crater. This is a large lunar impact crater which is about 180 km in diameter. This basin is located within a very big impact crater called the South Pole–Aitken basin (2,500 km in diameter and 13 km deep).

One of the most interesting experiments as a part of this mission was the one designed by the scientists from Chongqing University. This “mini lunar biosphere” experiment carried an 18cm bucket-like container holding air, water and soil. Inside this unit was carried cotton, arabidopsis – a small, flowering plant of the mustard family – and potato seeds, as well as fruit-fly eggs and yeast. The images sent back by the probe show a cotton plant has grown well, but so far none of the other plants had sprouted. Now, this experiment is over and sprouted cotton would decay in the container. This is for the first time in history that a biological matter has been flown to moon. Earlier, plants have been grown on the International Space Station (ISS).

Credit : ORF.online

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Tiangong-1 is a single-module space station operated by the China National Space Administration. The module was launched in 2011 and hosted two crews of taikonauts (Chinese astronauts) in 2012 and 2013. Since China's space agency discloses less information about its missions than other space agencies, the details surrounding the space station are not widely known.

The orbit of the space station passes over most of the civilized world, with the exclusion of northern latitudes that include the United States, Russia and Canada, as well as the extreme south of the world, including Antarctica and the tip of South Africa. However, most of the Earth is covered by water, reducing the chances of a crash in a populated area.

Tiangong-1 (whose name means "Heavenly Palace") weighs about 8.5 metric tons, and is about 34 feet long by 11 feet wide (10.4 meters by 3.4 meters). It contains an experiment module — where the astronauts live and work — and a resource module that contains propellant tanks and rocket engines.

The module was placed in low Earth orbit at about 217 miles (350 kilometers), at a slightly lower altitude than the International Space Station. Two solar arrays power the station, and it can house three astronauts. 

A primary goal for the module was to help the Chinese practice space dockings, which is an important skill for nations looking to build larger space stations or to send multiple spacecraft to the moon, Mars or other locations in the solar system.

Credit : Space.com

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Chang’e 1 was China’s first spacecraft to travel beyond Earth’s orbit. Its mission included stereoscopic imaging of the lunar surface, assaying the chemistry of the surface, and testing technologies that could be used in expanding the Chinese national space program to the Moon. 

Chang’e 1 carried eight instruments. A stereo camera and a laser altimeter developed a three-dimensional map of the surface with the camera tilting forward, down, and aft to illuminate three charge-coupled device (CCD) arrays. The interferometer spectrometer imager used a special lens system to project light onto an array of CCDs. X-ray and gamma-ray spectrometers measured radiation emitted by naturally decaying heavy elements or produced in response to solar radiation. These spectral data helped quantify the amounts of minerals on the lunar surface. The microwave radiometer detected microwaves emitted by the Moon itself and thus measured the thickness of the debris layer, or regolith, that fills the huge basins called maria. One aim of the regolith investigations was understanding how much helium-3 may be on the Moon. Helium-3 is a trace element in the solar wind, and the lunar surface has absorbed larger quantities of helium-3 than have been found on Earth. If mining on the Moon ever becomes practical, helium-3 would be a valuable fuel for nuclear fusion power. Other instruments monitored the solar wind and the space environment.

Credit : Britannica

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Tianwen-1 is an interplanetary mission by the China National Space Administration (CNSA) to send a robotic spacecraft to Mars, consisting of 5 parts: an orbiter, deployable camera, lander, drop camera, and the Zhurong rover. The spacecraft, with a total mass of nearly five tons, is one of the heaviest probes launched to Mars and carries 13 scientific instruments. It is the first in a series of planned missions undertaken by CNSA as part of its Planetary Exploration of China program.

The mission was launched from the Wenchang Spacecraft Launch Site on 23 July 2020 on a Long March 5 heavy-lift launch vehicle. After seven months of transit through the inner Solar System, the spacecraft entered Martian orbit on 10 February 2021. For the next three months the probe studied the target landing sites from a reconnaissance orbit. On 14 May 2021, the lander/rover portion of the mission successfully touched down on Mars, making China the third nation to both land softly on and establish communication from the Martian surface, after the Soviet Union and the United States.

The Tianwen-1 mission was the second of three Martian exploration missions launched during the July 2020 window, after the United Arab Emirates Space Agency's Hope orbiter, and before NASA's Mars 2020 mission, which landed the Perseverance rover with the attached Ingenuity helicopter drone.

China's Mars program started in partnership with Russia. In November 2011, the Russian spacecraft Fobos-Grunt, destined for Mars and Phobos, was launched from Baikonur Cosmodrome. The Russian spacecraft carried with it an attached secondary spacecraft, the Yinghuo-1, which was intended to become China's first Mars orbiter (Fobos-Grunt also carried experiments from the Bulgarian Academy of Sciences and the American Planetary Society). However, Fobos-Grunt's main propulsion unit failed to boost the Mars-bound stack from its initial Earth parking orbit and the combined multinational spacecraft and experiments eventually reentered the atmosphere of Earth in January 2012. China subsequently began an independent Mars project.

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Origami was on display at the Tokyo Olympics, which concluded on August 8. Athletes and journalists across venues were reportedly given cranes, flowers, butterflies made of paper, as a token of good health and cheer amid the gloomy reality of the COVID-19 pandemic. But did you know that this art of paper folding is even used in space engineering?

Origami engineering

It was American physicist Robert J Lang, who first studied the mathematics of origami and came up with real-world applications of origami to engineering problems. Today, origami is providing practical solutions to tackle complicated problems in space engineering.

Wondering how it is possible? Well, the ancient Japanese art of origami is adopted in space engineering to fold large objects and compress them so that they fit into smaller spaces inside the rocket and can be deployed once they reach their destination.

For instance, origami has helped NASA in designing the Starshade, a flower-shaped occulter in the Exoplanet Exploration Program in the New Worlds Mission Origami helped NASA fit the Starshade occulter, which is the size of a baseball field, inside a rocket. Once the Starshade opens in space, it will allow a space telescope to better see the planets around bright stars. Similarly, origami has been used in the CubeSats project where a huge antenna was packed into satellites the size of a briefcase. Origami has also been used in designing a robot called PUFFER. Applying the principles of origami, the scientists have been able to create a robot that can fold itself up and operate in small spaces. The robot will be able to enter cracks, crevices and explore all the areas that are otherwise inaccessible.

See how the simple art of paper folding is blended with rocket science.

Evolution of origami

Japan's love affair with paper began when the Buddhist monks imported the technology for manufacturing paper from China via Korea and created the beautiful washi paper, which is used in origami.

Origami butterflies, Ocho and Mecho, are the earliest known examples of origami mentioned in a short poem composed by thara Saikaku in 1680. Then in 1764 Sadatake Ise published the first set of instructions on paper folding in "Tsutsumi musibi no Ki". It developed further in the Edo era. Paper adomments were folded in different ways to symbolise different things. By the end of the period, more than 70 shapes were known including the crane, frog and samurai helmet.

Meanwhile, countries around the world too had their own traditions of folding. The Spanish tradition of folding paper birds was known as 'pajarita', whereas folding of napkins had become a practice among Italy's elites too. The Japanese and the Western folding traditions were merged by a German educator, Friedrich Frobel, who created the concept of kindergarten. Frobel made paper folding a part of the early years curriculum, thereby drawing the world's attention to this unique art.

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You know about exomoons, don't you? Moons orbiting a planet that is going around a distant star are referred to as exomoons. Even though finding exoplanets has become straightforward and we now achieve it with great success, the same isn't the case with exomoons. In fact, we haven't confirmed the detection of even one exomoon. A recent research has come up with a possible reason as to why this has been the case so far.

Transit technique

In order to detect exoplanets, orbiting space telescopes stare at many stars for as long as possible. When an exoplanet crosses in front of the face of its star from our point of view, the brightness of that star reduces a bit. This dip in brightness thus corresponds to an exoplanet transit and provides evidence of such planets orbiting other stars.

The problem with detecting exomoons stems from the fact that we need to identify a transit within a transit. Add to it the fact that moons are usually much smaller than planets, and it calls for stronger observations and equipment with higher sensitivity.

In this research, scientists used simplified simulations to find out if we are simply not good at finding exomoons or if exomoons itself are relatively rare. Turns out, it is the former for now.

Stable moons

Researchers found that planets close to their stars lose their moons rather quickly and the probability of having a stable moon increases for planets farther away from their star.

These findings are in tune with what we see in the solar system, where Mercury and Venus do not have any moons, while Earth's moon is a permanent fixture.

The transit method that we use to detect exoplanets works best when we are looking for planets that are close to their stars. So based on this recent research, it naturally follows that our planet-finding technique is biased towards finding planets that are less likely to retain their moons. It is no surprise, therefore, that we haven't identified exomoons yet.

As our techniques and instruments improve, we will soon start detecting exoplanets that are farther away from their stars. And when we start doing that, the likelihood of finding exoplanets with exomoons would also improve significantly.

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If we are asked to name a planet in the solar system that has rings around it, our answer would be Saturn, perhaps nine out of 10 times. Even if we are asked to just imagine a planet with rings, most of us would likely be thinking of Saturn. This is because we strongly associate Saturn with its rings.

This doesn’t mean, however, that Saturn is the only planet in the solar system that has rings. On the contrary, every gas giant in the solar system – Jupiter, Saturn, Uranus, and Neptune – has a ring around it.

Historic Neptune flyby

Among these, it was Neptune’s rings that were the last to be discovered. While scientists suspected for some years that Neptune must have rings around it, it was only when Voyager 2 made its flyby that it was proven beyond any doubt.

Launched in August 1977, Voyager 2 took 12 years to get to Neptune, having observed Jupiter, Saturn, and Uranus along the way. And then, in a matter of weeks, Voyager 2 discovered six new moons and four rings around Neptune.

Even though Voyager 2 had completed five planetary encounters before heading to Neptune, the big blue planet posed certain specific challenges. Thirty times farther from the sun than Earth is, and receiving just one-thousandth the amount of sunlight that Earth does, there was low light in this region.

Light and distance

This meant that Voyager 2’s cameras required longer exposure to get good quality images during the flyby. Long exposures, however, would have made the images blurry as the spacecraft reached speeds up to 90,000 kmph relative to Earth. To counter this, Voyager 2’s team programmed the spacecraft to fire its thrusters gently during close approach, enabling it to keep the camera focussed on its target, without compromising on the spacecraft’s speed and direction.

Apart from the lighting, the huge distance meant that radio signals reaching Earth from Voyager 2 were weaker than those from other flybys. Voyagers (both 2 and 1), however, communicated with Earth via the Deep Space Network (DSN). The DSN made use of antennas in Madrid, Spain; Canberra, Australia; and Goldstone, California, the U.S.

While the three largest DSN antennas were 64m wide during Voyager 2’s encounter with Uranus in 1986, the dishes were expanded to 70m to assist communication during the Neptune flyby. Other non-DSN antennas were also employed as an auxiliary measure, ensuring that the spacecraft could send back more pictures in a reliable manner within any time-frame.

Daily updates

With no Internet to allow the entire world to see the pictures at the same time, the images were available in real time in only a few locations. As the excitement was palpable world over regarding the Neptune flyby, the team behind Voyager 2 decided to provide public updates as often as possible, leading to daily press conferences from August 21-29, 1989.

On August 22, 1989, Voyager 2 provided the images that serve as the definitive discovery of Neptune’s rings. A few days later, the spacecraft made its closest approach to Neptune. After successfully completing another planetary encounter, Voyager 2 headed off on its interstellar exploratory voyage.

Five main rings

We now know that Neptune has at least five main rings and four prominent ring arcs. Starting from the ring nearest to the planet, these are named Galle, Leverrier, Lassell, Arago, and Adams.

While the rings are currently thought to be short-lived and relatively young, the arcs are clumps of dust that are peculiar to Neptune’s ring system. The outermost ring, Adams, is where four prominent arcs Liberty, Equality, Fraternity, and Courage can be found.

Even though the laws of motion predict that these arcs would be spread out evenly, they actually stay clumped together, making them unusual. While we don’t yet know for certain, scientists suggest that the gravitational effects of Galatea, a moon just inward from Adams, is probably what stabilises these arcs. There’s this, and more, to find out and learn from the rings of Neptune.

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