Category Exploring the Universe

What about space dust as Earth’s sun shield?

The heat and energy from the sun is what drives life on Earth. That said, humanity is now collectively responsible for so much greenhouse gases that Earth's atmosphere now traps more and more of the sun's energy. This has led to a steady increase in the planet's temperature, and global warming and climate change are causes for concern.

One suggested strategy to reverse this trend is to try and intercept a small fraction of sunlight before it reaches Earth. Scientists, for decades, have considered the possibility of using screens, objects or dust particles to block 1-2% of the sun's radiation and thus mitigate the effects of global warming.

Dust to block sunlight

A study led by the University of Utah explored the idea of using dust to block a bit of sunlight. Different properties of dust particles, quantities of dust and the orbits that would work best for shading Earth were studied. The results were published on February 8, 2023 in the journal PLOS Climate.

Launching dust from Earth to a station at the Lagrange Point between Earth and the sun (L1) would prove to be most effective. The prohibitive costs and efforts involved here, however, might necessitate an alternative, which is to launch lunar dust from the moon.

These two scenarios were arrived at after studying a shield's overall effectiveness, which depends on its ability to sustain an orbit that casts a shadow on Earth. In computer simulations, a space platform was placed at the L1 Lagrange Point (point between Earth and the sun where gravitational forces are balanced) and test particles were shot along the L1 orbit.

While a precise launch was able to create an effective shield for a while, the dust would be blown off by solar winds, radiation, and gravity within the solar system. This would mean that such a system would require an endless supply of dust to blast from L1, making the cost and effort involved astronomical.

Moondust might work

 The second scenario of shooting moondust towards the sun might prove to be more realistic as the inherent properties of lunar dust allow it to work as a sun shield. After studying simulations of lunar dust scattered along different courses, an ideal trajectory that aimed towards L1 was realised.

The authors were clear in stating that their study only looks at the possible impact of such a strategy and do not evaluate the logical feasibility of these methods. If it works, this could be an option in the fight against climate change as it would allow us to buy more time.

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Dark Matter: A mystery of the Universe

Dark matter accounts for 27 percent of all matter and energy in the universe. What we see, the regular matter is just 5 percent of the universe. The dark matter can be failed stars or white dwarfs or black holes.

First, there was the Big Bang. For several million years after that, there was nothing – no stars, planets, moons or galaxies. This continued for 150 million years after the great Big Bang. Time went by. The first stars were created. Matter fused, stars clumped together, galaxies collected together. The formation of our planetary system began. To hold the solar system and clusters of galaxies together, we had gravity, our glue. Swiss astronomer Fritz  Zwicky who used the term ‘dark matter first. He coined the term ‘Dunkle Materie’ to denote the invisible matter.

Dark Matter

But in some clusters, the space between the galaxies contains hot gases which cannot be seen using light telescopes. After measuring this gas, the scientists came to the opinion that there is more material involved in these clusters than meets the eye and that they cannot be detected. The undetected matter could amount to some five times the material in the cluster. This invisible matter that cannot be detected is called the ‘dark matter. Dark matter accounts for 27 percent of all matter and energy in the universe. What we see, the regular matter is just 5 percent I of the universe.

It was the Swiss astronomer Fritz Zwicky who used the term ‘dark matter first. He coined the term ‘Dunkle Materie’, which translates to dark matter, to denote the invisible matter. His subject was the Coma galaxy cluster. It should be noted that the speed of revolution of a particular cluster is dependent on the weight and position of the matter in the cluster. When he measured the speed, he found out that the cluster had more mass than it was supposed to meaning there was more matter involved. This was further confirmed by other scientists whose work on other galaxies suggested that they had more mass. The presence of dark matter was thus established.

What makes up Dark Matter

According to scientists, dark matter can be failed stars or white dwarfs or black holes. But these are just suggestions and the dark matter still continues to be a mystery. Scientists have however found ways to indirectly study dark matter. This is done by using gravitational lensing. Studies are still being carried out and we are just unraveling all the secrets of the universe.

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Voyager 1’s tryst with Jupiter and Saturn

On November 6, 1980, Voyager 1 snapped a picture of Saturn while still 8 million km away from it. Scientists discovered a 15th moon orbiting Saturn from the photo the following day. In a year in which it has completed 45 years of operation,

You must be aware that the twin Voyager probes are now travelling in interstellar space, 45 years since their launch. Before they got there, however, they visited the gas giants in our solar system, gleaning a wealth of information from the flybys. While Voyager 2 flew by all four gas giants – Jupiter, Saturn, Uranus, and Neptune, – Voyager 1 focussed on Jupiter and Saturn.

Even though Voyager 1 is the first spacecraft to travel beyond the solar system and reach interstellar space, it wasn’t the first of the probes to be launched. Launched on September 5, 1977-two weeks after Voyager 2 – Voyager 1, however, was the first to race to Jupiter and Saturn.

Gravitational slingshots

The Voyager missions were planned in such a way that they could maximise a special alignment of the outer planets that happens only once in 176 years. This alignment aided the spacecraft to efficiently use their limited fuel as they moved like a slingshot from one planet to another using gravitational assist.

All the successes that Voyager 1 has achieved might have come to nothing right on the day of the launch. Its rocket came within 3.5 seconds of running out of fuel, meaning Voyager 1 wouldn’t have even got off the ground.

Jupiter flyby

Once it did, however, it raced past its twin, going beyond the asteroid belt before Voyager 2 did. And in April 1978, Voyager 1 beamed back the first pictures of Jupiter back to Earth. By March 1979, it had spotted a thin ring around the giant planet. Apart from sending back detailed photographs of Jupiters Galilean moons (lo, Europa, Ganymede, and Castillo), Voyager 1 also found two new moons – Thebe and Metis.

Voyager 1 collected plenty of data and also made some interesting discoveries about Jupiter’s satellites. Following its closest approach to Jupiter on March 5, 1979, when it came within 2,80,000 km, it headed over to Saturn, a journey that took it just a little over a year.

Just like how its visit to Jupiter had a lot of findings, so it was with Saturn as the ringed planet revealed many of its secrets. As it flew ever closer to Saturn in October-November 1980, Voyager 1 spotted a number of moons, observed its rings and already known moons, and collected data that had scientists digging for decades.

Programmed searches

One of the moons that Voyager 1 spotted was Atlas, the 15th moon orbiting Saturn. In a photograph taken by the spacecraft on November 6 when it was still 8 million km away, the moon was visible near the bottom of the picture.

The first of several programmed searches for new satellites of Saturn thus had success right away as the Voyager imaging team scientists discovered the moon on November 7. An inner moon of Saturn, orbiting around the outer edge of Saturn’s A ring, Atlas takes 14.4 hours to complete its trip around the planet.

Unique perspective

Following its closest approach of Saturn on November 12, Voyager 1 looked back on Saturn four days later on November 16, to observe Saturn and its rings from its unique vantage point. With its primary mission concluded following the Saturn encounter, the focus moved to tracking the spacecraft as it headed to interstellar space.

Having recognised that the Voyagers would eventually make it to interstellar space, NASA had placed Golden Records on board the spacecraft. Designed to carry images, music, and voices from Earth out into the cosmos, the Golden Records have spoken greetings in over 50 languages.

Voyager 1 became the first spacecraft to go beyond the solar system and reach interstellar space on August 25, 2012. At that point, Voyager 1 was over 18 billion km away from the sun. Over a decade later, it has travelled even farther and is now over 23 billion km away from the sun. Voyager 1 has enough fuel to supply power to its instruments until at least 2025, after which it will likely stop collecting scientific data.

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What are the secrets of Enceladus moon?

Discovered on August 28, 1789, Enceladus is a natural satellite of Saturn. This moon, which remained in relative obscurity for nearly 200 years, is now one of the most scientifically interesting destinations in our solar system.

The possibility of worlds other than our own Earth where life could exist has enthralled us for a long time. Often seen in the realm of science fiction, we might be inching ever so closer to it in reality as scientists have identified a handful of worlds that have some of the ingredients needed for life. One of them is Enceladus, an icy moon that is the brightest in the solar system.

Enceladus was discovered on August 28, 1789 by British astronomer William Herschel, more popular for discovering the planet Uranus. Little is known about how William went about it and made his discovery.

A dwarf named after a giant

What we do know, however, is that it was William’s son, John Herschel, who gave the moon its name Enceladus, after the giant Enceladus of Greek mythology. In his 1847 publication Results of Astronomical Observation made at the Cape of Good Hope, John suggested names for the first seven moons of Saturn that had been discovered, including Enceladus. He picked these particular names as Saturn, known in Greek mythology as Cronus, was the leader of the Titans.

For nearly two centuries, very little was known about Enceladus. That changed in the 1980s, when the U.S. spacecrafts Voyager 1 and Voyager 2 flew by the moon, capturing images. The pictures indicated that the icy surface of this small moon is very smooth in some places and bright white all over.

Enceladus, in fact, is the most reflective body in the solar system. Scientists, however, didn’t know why this was the case for a few more decades. Enceladus reflective capability implies that it reflects almost all the sunlight that strikes it, leading to extremely cold surface temperatures, of the order of -200 degree Celsius.

E ring and tiger stripes

Shortly after NASA’s Cassini spacecraft began studying Saturn’s system in 2004, Enceladus started revealing its secrets. By spending over a decade in the vicinity of the small moon, including flybys as close as 50 km, Cassini was able to unearth a wealth of information about Enceladus.

Cassini discovered that icy water particles and gas gush from the moon’s surface at about 400 metres per second. These continuous eruptions create a halo of fine dust around the moon, which supplies material for Saturn’s E ring. While a small fraction of this remains in the ring, the remaining falls like snow back onto the moon’s surface, thereby making it bright white. Scientists informally call the warm fractures on Enceladus’ crust from which the water jets come from as “tiger stripes”.

By measuring the moon’s slight wobble as it orbits Saturn and from gravity measurements based on the Doppler effect, scientists were able to determine that these jets were being supplied by a global ocean inside the moon. As this ocean supplies the jet, which in turn produces Saturn’s E ring, it follows that studying material from the E ring is akin to studying Enceladus’ ocean.

While the E ring is mostly made of ice droplets, there is also the presence of nanograins of silica that can be generated only where liquid water and rock interact at temperatures above 90 degrees Celsius. Along with other evidence that has been gathered, this suggests the existence of hydrothermal vents deep beneath this moon’s shell, similar to those on the Earth’s ocean floor.

Orbital resonance

Enceladus takes 33 hours for its trip around Saturn, which is nearly half of the time taken by the more distant moon Dione. Enceladus is thus trapped in an orbital resonance with Dione, whose gravity stretches Enceladus’ orbit into an elliptical shape. This means that Enceladus is sometimes closer to Saturn and at other times farther leading to tidal heating within the moon.

Running just over 500 km across, Enceladus is small enough to fit within the Indian State of Maharashtra, which runs around 700 km north-south and 800 km east-west. What it lacks in size it more than makes up for in stature, as Enceladus has a global ocean, unique chemistry, and internal heat. All this means that even though we still have plenty of data about the moon to pore over, explorers will eventually plan a return to Enceladus to learn more of its secrets.

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WHY ARE JUPITER’S RINGS NOT LIKE THOSE OF SATURN?

If we talk about ringed planets, more often than not every one of us will be talking about Saturn. This, despite the fact that all four giants in our solar system Jupiter, Saturn, Uranus, and Neptune – in fact have rings.

This is likely because Saturn has spectacular rings. While the rings of Jupiter and Neptune are flimsy and difficult to view with stargazing instruments traditionally used, the rings of Uranus aren’t as large as that of Saturn’s.

As Jupiter is bigger than Saturn, it ought to have rings that are larger and more spectacular than that of its neighbour. As this isn’t the case, scientists from UC Riverside decided to investigate it further. Their results were accepted by the Planetary Science journal and are available online.

Dynamic simulation

A dynamic computer simulation was run to try and understand the reason why Jupiter’s rings look the way they do. The simulation accounted for Jupiter’s orbit, the orbits of Jupiter’s four main moons, and information regarding the time it takes for rings to form.

The rings of Saturn are largely made of ice, some of which may have come from comets also largely made of ice. When moons are massive, their gravity can either clear the ice out of the planet’s orbit, or change the ice’s orbit such that it collides with the moons.

Massive moons

The Galilean moons of Jupiter Ganymede, Callisto, lo, and Europa- are all large moons. Ganymede, in fact, is the largest moon in our solar system. The four main massive moons of Jupiter would thus destroy any large rings that might form around the planet. This also means that Jupiter is unlikely to have had large. spectacular rings at any time in the past as well.

Ring systems, apart from being beautiful, help us understand the history of a planet. They offer evidence of collisions with moons or comets, indicating the type of event that might have led to their formation. The researchers next plan to use the simulations to study the rings of Uranus to find out what the lifetime of those rings might be.

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What makes Russia a prominent country in space explorations?

Russia has achieved great heights in the field of space technology and space exploration, and its national space agency is known as Roscosmos. These achievements can be traced back to Konstantin Tsiolkovsky, who is known as the father of theoretical astronautics. His works inspired Soviet rocket engineers, such as Sergey Korolyov, Valentin Glushko, and many others to contribute immensely to the Soviet space programme in its early stages, leading to its participation in what is called the ‘Space Race’.

There is a name that one cannot forget in the history of space expeditions – Sputnik-1. In 1957, this satellite was launched by Russian scientists as the first Earth-orbiting artificial satellite. Later, in 1961, Yuri Gagarin made the first human trip into space. This was followed by a number of other Soviet and Russian space explorations, which include the journey of Valentina Tereshkova in 1963 to become the first woman in space. She flew alone in Vostok 6. Russia also holds the record for the first human to have conducted a spacewalk-in 1965, Alexei Leonov exited the space capsule of the mission Voskhod-2 and walked in space.

Can you guess what other records Russia has in this area? They sent the first animal into outer space. Travelling in Sputnik-2 in 1957, a dog named Laika became the first animal to orbit the Earth. In 1966, Luna-9, landed on the Moon, making it the first spacecraft to achieve a survivable landing on a celestial body. In 1968, Zond-5 completed the mission of circumnavigating the Moon with two tortoises and other life forms from Earth. Later, Russia’s Venera-7 became the first spacecraft to land on Venus. Following this achievement, Mars-3 became the first spacecraft to land on Mars in the very next year 1971. During this time, Russia also sent Lunokhod-1, which became the first space exploration rover. Salyut-1 became the world’s first space station, which was yet again a Russian project. As per the 2021 data, Russia had 167 active satellites in space, which is the world’s third-highest count.

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