My Science School

Space junk, or space debris, is any piece of machinery or debris left by humans in space.

It can refer to big objects such as dead satellites that have failed or been left in orbit at the end of their mission. It can also refer to smaller things, like bits of debris or paint flecks that have fallen off a rocket.

Some human-made junk has been left on the Moon, too.

How much space junk is there?

While there are about 2,000 active satellites orbiting Earth at the moment, there are also 3,000 dead ones littering space. What's more, there are around 34,000 pieces of space junk bigger than 10 centimetres in size and millions of smaller pieces that could nonetheless prove disastrous if they hit something else.

How does space junk get into space?

All space junk is the result of us launching objects from Earth, and it remains in orbit until it re-enters the atmosphere.

Some objects in lower orbits of a few hundred kilometres can return quickly. They often re-enter the atmosphere after a few years and, for the most part, they'll burn up - so they don't reach the ground. But debris or satellites left at higher altitudes of 36,000 kilometres - where communications and weather satellites are often placed in geostationary orbits - can continue to circle Earth for hundreds or even thousands of years.

What risks does space junk pose to space exploration?

Fortunately, at the moment, space junk doesn't pose a huge risk to our exploration efforts. The biggest danger it poses is to other satellites in orbit.

These satellites have to move out of the way of all this incoming space junk to make sure they don't get hit and potentially damaged or destroyed.

In total, across all satellites, hundreds of collision avoidance manoeuvres are performed every year, including by the International Space Station (ISS), where astronauts live.

Space junk in numbers

2,000 active satellites in Earth's orbit

3,000 dead satellites in Earth's orbit

34,000 pieces of space junk larger than 10 centimetres

128 million pieces of space junk larger than 1 millimetre

One in 10,000: risk of collision that will require debris avoidance manoeuvres

25 debris avoidance manoeuvres by the ISS since 1999

How can we clean up space junk?

The United Nations ask that all companies remove their satellites from orbit within 25 years after the end of their mission. This is tricky to enforce, though, because satellites can (and often do) fail. To tackle this problem, several companies around the world have come up with novel solutions.

These include removing dead satellites from orbit and dragging them back into the atmosphere, where they will burn up. Ways we could do this include using a harpoon to grab a satellite, catching it in a huge net, using magnets to grab it, or even firing lasers to heat up the satellite, increasing its atmospheric drag so that it falls out of orbit.

Credit :  Natural History Museam

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Io or Jupiter I, is the innermost and third-largest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth’s moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water (by atomic ratio) of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus's lovers.

With over 400 active volcanoes, Io is the most geologically active object in the Solar System.

 This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean moons—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io's silicate crust. Some of these peaks are taller than Mount Everest, the highest point on Earth's surface.  Unlike most moons in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is composed of extensive plains with a frosty coating of sulfur and sulfur dioxide.

Io's volcanism is responsible for many of its unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various subtle shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur. Numerous extensive lava flows, several more than 500 km (300 mi) in length, also mark the surface. The materials produced by this volcanism make up Io's thin, patchy atmosphere and Jupiter's extensive magnetosphere. Io's volcanic ejecta also produce a large plasma torus around Jupiter.

Io played a significant role in the development of astronomy in the 17th and 18th centuries; discovered in January 1610 by Galileo Galilei, along with the other Galilean satellites, this discovery furthered the adoption of the Copernican model of the Solar System, the development of Kepler's laws of motion, and the first measurement of the speed of light. Viewed from Earth, Io remained just a point of light until the late 19th and early 20th centuries, when it became possible to resolve its large-scale surface features, such as the dark red polar and bright equatorial regions. In 1979, the two Voyager spacecraft revealed Io to be a geologically active world, with numerous volcanic features, large mountains, and a young surface with no obvious impact craters. The Galileo spacecraft performed several close flybys in the 1990s and early 2000s, obtaining data about Io's interior structure and surface composition. These spacecraft also revealed the relationship between Io and Jupiter's magnetosphere and the existence of a belt of high-energy radiation centered on Io's orbit. Io receives about 3,600 rem (36 Sv) of ionizing radiation per day.

Further observations have been made by Cassini–Huygens in 2000, New Horizons in 2007, and Juno since 2017, as well as from Earth-based telescopes and the Hubble Space Telescope.

Credit : Wikipedia 

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Nasa has discovered a rare and highly valuable asteroid called '16 psyche’. It was found by nasa’s hubble space telescope. The asteroid is located in our solar system’s asteroid belt between the planets of mars and jupiter.

According to a study published by the planetary science journal on monday, asteroid '16 psyche’ is located roughly 370 million kilometres (230 million miles) from the earth and measures 226 kilometres across (140 miles).

The most interesting thing about the asteroid is what it's made of. Unlike other asteroids made up of either rocks or ice, psyche is made up of metals.

One of the study's authors tracy becker said that they usually come across meteorites that have metal deposits but since psyche is made up entirely of metals, it is quite unique. 

Psyche's size and presence of metal deposits means that it could be worth $10,000 quadrillion ($10,000,000,000,000,000,000), which is equivalent to ten thousand times the global economy in 2019.

Researchers used the ultraviolet spectrum data collected by the space telescope imaging spectrograph on the hubble telescope during two observations made in 2017.

The data showed them that psyche's surface could be made of pure iron but they also found that the presence of iron composition as small as 10 percent could dominate ultraviolet reports. Psyche is believed to be the dead core of a planet that might have failed during its formative stages or it could also be the result of many violent space collisions.

Nasa has already targeted the exploration of asteroid psyche with the launch of nasa discovery mission psyche, which is expected to be launched in 2022. The psyche space probe will be sent atop a spacex falcon heavy rocket and will reach the asteroid by 2026, and hopefully uncover its exact metal content and other facets.

Credit :  India times 

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My relationship with my parents is in trouble ... due to my choice for higher studies. I want to join a particular course of my choice, but my parents feel I shouldn't just because their plans for my future are different. I have always done what my parents have wanted me to do. But now, going against their wishes in favour of mine is making me feel guilty about disobeying my parents. How should I handle this situation?

Hey dear, you are feeling guilty that you are 'disobeying' your parents to join a course of your choice because till now you have always obeyed them.

Like all parents, they may be thinking about economic aspects, social acceptance, where you study and work (location), and safety instead of your interests and your talent/skills. However, you are going to study and work in a particular field, so it is also important to enjoy what you do.

There are two things to do: One is to convince them - in a firm yet caring manner that this course is really what you want to do, and how it is right for you. Second is to address their fears, if any. You could seek professional advice from a career counsellor if you wish. Do your homework about what they might want to know, e.g., detailed information about the course, career prospects, income, your interests, your talents and so on. Request that they give you a fair hearing and share your thoughts; ask for their views and suggestions and answer their questions. Assure them that you will see the course through and take responsibility for yourself.

If you are firm about what you want to do and address any fears they may have, it is more likely that your parents will understand and respect your choice. Good luck!

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I am easily affected by people's feelings about me. If someone says something negative about me or puts me down, I start worrying a lot about it, and as a result, I get headaches and I am unable to concentrate on anything. I feel it so much that I cannot sleep at night as I keep thinking about what happened. How can I overcome this problem?

Hi dear, you are sensitive to others' feelings about you. This makes you overthink what happened, which affects your emotional and physical health, and your sleep.

When someone criticises you, first calm yourself. Breathe and count backwards from ten to one. Or notice any five objects of different colours in the room. When you are calmer, question these negative remarks. Are any of them true? What is the evidence that they are true? What is the evidence that they are not true? If they are true, you can use them as feedback to improve. If they are not, then you know the other person is probably expressing their opinion or their frustration.

Reflect on what affects you when someone says something negative or puts you down. We usually feel affected because we want to be seen as 'nice' by everyone and often don't respect ourselves enough. So, instead of thinking 'I am not good enough', say 'I am learning and growing'. Know your own strengths and weaknesses and accept, love and respect yourself as you are. Befriend people who respect you and learn to say 'no' to those don't. Participate in youth activities that help develop your personality and your leadership skills.

When you feel more confident, firmly let people who pass negative remarks know that you find their statements too negative; and it is best that they only give you feedback you can work on. Show them that you are fine with yourself the way you are. Stand up for yourself!

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My problem is that whenever any female friend of mine says something nice to me I feel very shy and embarrassed. I love sports and am happy to indulge in social activities. But when it comes to girls praising or complimenting me, it's an embarrassing situation for me. Am I abnormal?

Hey dear, your shyness and self-consciousness cause you to be embarrassed when your female friends compliment you, and this is not abnormal at all. It is perfectly normal to feel shy with those of the opposite gender in your teens.

If you are uncomfortable and embarrassed when the spotlight is on you, is it that you think you don't deserve the attention and the compliments? Or are you afraid that someday they will change their minds about you and think that you're not good enough?

Start by receiving a compliment with grace. Practise saying, "Thank you' and smiling in front of a mirror and then simply say 'Thank you' and smile when they pay you a compliment next. Learn how to pay a sincere compliment to them too. It will take the attention off you and yet make you appreciated.

Girls are human beings too, so learn the art of conversation. Think of an interesting topic and bring it up. Ask for their views. This will take the spotlight off yourself and distribute the attention among many others. Plus, you will find common interests.

Most importantly, your shyness can be a strength it shows that instead of being brash or rude you are a caring and gentle person. And who doesn't like a tough guy who can be gentle too!

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Stars are born and they die. When a star uses up all its fuel which is in the form of hydrogen, it no longer releases energy. Gravitational forces take over and the star slowly collapses inwards. In the end the star may fade out quietly to become a white dwarf or it may explode.

Whether a star collapses or explodes depends on its mass. If it is a heavyweight star which means if it is more than about 1.4 times the mass of our sun, it becomes unstable and explodes to become a very bright star called supernova. If it is less massive it shrinks into a white dwarf.

The critical mass of 1.4 suns is known as the Chandrasekhar limit. This limiting factor was predicted in the 1930s by the Indian-American astrophysicist Subrahmanyan Chandrasekhar.

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Although we usually see only the brightly lit part of the moon during its crescent phase, we sometimes see the other part too, though dimly lit.

What's the reason?

Earth reflects the sun's light falling on it just like the  moon does. The earth, in fact, is a better reflector than the moon. The oceans which cover three-fourths of the earth's surface, reflect a lot of solar radiation back into space. So just as we have moonlight here, there is earthlight on the dark side of the moon. It is this earthlight which makes the moon beyond the crescent dimly visible to us.

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