What powers a spacecraft?

Scientists send spacecraft to probe objects in space. These spacecraft carry instruments that help them take pictures and collect data in space and send them back to Earth. But to do this, the spacecraft needs electricity So what powers it?

Based on the mission it is assigned, and factors such as where the spacecraft is travelling, what it plans to do there and how long it needs to work engineers choose the best way to power a spacecraft.

The Sun                     

One source of power engineers consider is energy from the Sun, or solar power. Spacecraft that orbit close to Earth are dose enough to the Sun to use solar power. These spacecraft are fitted with solar panels, which convert the Sun's energy into electricity. The electricity from the panels charges a battery in the spacecraft and can be used even when the spacecraft doesn't have direct sunlight


Sometimes, when the mission is only for a short duration, such as the Huygens probe that landed on Titan, Saturn's largest moon, and meant to work only for a few hours, engineers may power the spacecraft with batteries. These batteries are designed to be tough since they need to withstand the harsh environment of space.


An atom is a tiny building block of matter. Atoms need to store a lot of energy to hold themselves together. However, atoms such as radioisotopes are unstable and begin to fall apart. As they fall apart, they release energy as heat. A radioisotope power system uses the temperature difference between the heat from the unstable atoms and the cold of space to produce electricity. This system produces power for a very long time even in harsh environments. That's why this system has been used to power many of NASA's missions, including the two Voyager spacecraft that continue to send back information after over four decades in space.

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What’s space weather?

Ever wondered about the weather in space? Before that, let's think about what dictates the weather on our planet. The Sun, which is our source of energy, plays a titular role in governing the weather on Earth. And so does it create the weather in space! The activities on the Sun's surface can lead to a type of weather in space and this is called space weather.

Space weather is dependent on activities and changes on the Sun's surface such as coronal mass ejections (eruptions of plasma and magnetic field structures) and solar flares (sudden bursts of radiation). We are shielded from these bursts of radiation and energy by Earth's magnetosphere, ionosphere, and atmosphere.

Impact of space weather

The Sun is some 93 million miles away from our Earth. Yet, space weather can affect us and the solar system. The electric power distribution grids, global satellite communication, and navigation systems are all susceptible to conditions in space that are impacted by the Sun.

Space weather can damage satellites, affect astronauts and even cause blackouts on Earth. Such incidents are rare but they have happened before.

CME, solar flare

When a CME reaches Earth, it leads to a geomagnetic storm. This can disrupt services, damage power grids and cause blackouts.

For instance, back in 1989, a powerful geomagnetic storm led to a major power blackout in Canada. As a result, around 6 million people were left in the dark for about 9 hours.

Solar flares can also result in disruption of services. The strongest and most intense geomagnetic storm ever recorded occurred in 1859. This was caused by a solar flare. Called the "Carrington Event and named after England's solar astronomer Richard Carrington who observed the activity through his telescope, the geomagnetic storm caused damage, disrupting the telegraph system on Earth. It also led to the aurorae, a result of geomagnetic activity, being visible in regions such as Cuba and Hawaii.

While telegraph networks are a thing of the past, our communications system and technologies can still be impacted by space weather. Even as most of the charged particles released by the Sun get shielded away due to Earth's magnetic field, sometimes space weather can affect us. We need to track the activities on the Sun's surface and understand them to protect the people and systems.

Any warning regarding bad space weather can help scientists send alerts and lessen the damage caused by it. Space agencies have observatories monitoring the Sun and detecting solar storms. These help in mitigating the effect of bad space weather.

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Which was the cancelled mission that succeeded ?

On October 28, 1971. Great Britain officially entered the space race. becoming the sixth country to place a satellite into orbit using their own launch vehicle While the Prospero satellite had been successfully launched, the project responsible for it had been scrapped months earlier. A.S.Ganesh takes a look at a cancelled mission that still succeeded....

What were you doing when Chandrayaan 3 created history by landing near the south pole of the moon? This is one question that you might keep encountering throughout your lifetime. It is human nature to link associate and talk about what we as individuals were doing when something historic pans out.

These things however, are also a by-product of how we are made to feel about a particular event. For even when something historic takes place, it might not always create waves if there isn't enough hype around it. The successful launch of the Prospero satellite is one such event.

The second half of the 20th Century was an exciting time in the space race. While the US. and the Soviet Union were at the forefront, the UK was only third to them in the field of rocket technology. Despite having a workable satellite launch programme and plans for human-based missions, it all came apart for Great Britain in a matter of years.

No fanfare

Britain became the sixth nation to place a satellite into orbit with a carrier rocket developed indigenously on October 28, 1971. Unlike the frenzy surrounding the success of Chandrayaan-3, there was little fanfare associated with it.

Even if we are to account for the half a century in between and the way in which news is disseminated with today's technology and social media, what happened with Prospero would still be found wanting. While the American and Soviet space programmes of the time were being celebrated, Prospero's successful launch was a low-key affair.

Black Arrow project

Regardless of how it was received. Prospero's launch was a triumph. The scientists and engineers at the Royal Aircraft Establishment had been involved with the British space programme from late in the 1950s and all their skills had been invested on this satellite.

The Black Arrow project programme was a continuation of the U.K.'s missile defence programme. The first attempt to launch a satellite (X-2) was a failure in September 1970 as the second stage of the rocket failed to pressurise. With this literally being their last chance, the team based at the launch site in Woomera, Australia did everything with extreme caution. The Black Arrow rocket was launched on October 28, 1971 from Woomera and within minutes the Prospero satellite, manufactured by the British Aircraft Corporation and Marconi, was placed successfully in a polar orbit.

Joy and regret

 The joy that the success brought was mixed with sadness for all those involved because the British government had cancelled the Black Arrow project three months earlier owing to escalating costs and funding coming to a standstill. The government had agreed upon one final launch attempt which resulted in Prospero's success. With the government distancing itself from the project, there was little about the mission for the consumption of the public. It took two days for the news of the successful launch to reach the U.K. and even then it did not make it to the front page of most newspapers.

Transmits for decades

The 66 kg Prospero was a tiny device designed to test systems for future launches (that never came about) and carried a single scientific instrument. While the tape recorders it carried stopped functioning in 1973. Prospero transmitted a signal for over two decades and continues to orbit the Earth Just before the age of the commercial satellites began, the British government pulled the plug after having decided that space was largely a waste of money. Prospero is not only the first, but remains so far the only British satellite launched on a British-built rocket.

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Ever wondered what the cosmos smells like?

Well, wait, can you smell in space? It is a vacuum, right? The space is empty. And if you were out in space, you cannot risk taking off your helmet and try smelling the cosmos. Our noses wouldn't work in a vacuum and doing so can lead to a casualty. But we do know what the space smells like. It is metallic.

Astronauts who have been abroad on the ISS have said that they experienced a metallic aroma on the surface of their spacesuits. They can't smell outer space when they are floating in it. But once the astronauts were back in their space station and removed their helmets, they always said that there was a metallic aroma. Their suit, helmet, gloves, and tools would get permeated with this distinct smell.

Most astronauts have defined the smell as that of burning metal, gunpowder, ozone, seared steak and so on. The smell of outer space is important because it can tell us a lot about the chemical composition of our galaxy. There have been many theories concerning the distinct smell. Let's learn more about the smell.

Probable explanations

One of the explanations for the smell of space is the chemical reaction (oxidation) that occurs in the spacecraft during re-pressurisation. Oxidation happens when the atomic oxygen (single atoms) clinging onto the spacesuit of the astronaut combines with the O2 in the cabin during re-pressurisation and make ozone (O3).

The other explanation is even more intriguing. It says that the smell is that of dying stars! A lot of energy gets released when a star dies. As a result of this process. Many pungent compounds such as polycyclic aromatic hydrocarbons (PAHs) are created and these float around in the universe. The PAHS when combined with air within the spacecraft may be responsible for the unique smell.

NASA's perfume

Did you know that NASA tried to recreate the smell of space? This happened in 2008 when the space agency contacted chemist Steve Pearce to recreate the smell. It took him four years to come up with the smell. It was used for astronaut training purposes and to get the astronauts accustomed to the smell of space beforehand. Later, a perfume was released in the public domain by the chemist's company using the formula. The perfume christened "Eau de Space" mimicked the smell of space.

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Naming planetary objects?

On August 23, India celebrated a technological triumph when Chandrayaan-3 landed near the Moon's South Pole at 6:04 p.m. Since then, there has been a discussion on the naming of the landing spot, which Prime Minister Narendra Modi has termed Shiv Shakti.

Do you know how are planetary objects are usually named?

International Astronomical Union             

The International Astronomical Union (IAU), founded in 1919, is responsible for assigning names to celestial bodies and surface features on them. In the IAU, there are numerous Working Groups that suggest the names of astronomical objects and features.

In 1982, the United Nations, at its 'Fourth Conference on the Standardisation of Geographical Names held in Geneva, recognised the role of the IAU by adopting its resolution on extraterrestrial feature names.

Key rules

The IAU has set some rules for naming planetary objects. Some of the most important rules are -the names should be simple, clear, and unambiguous; there should not be duplication of names; no names having political, military or religious significance may be used, except for names of political figures prior to the 19th Century; and if a name of a person is suggested, then he/she must have been deceased for at least three years, before a proposal may be submitted.

Process of naming

When the first images of the surface of a planet or satellite are obtained, themes for naming features are chosen and names of a few important features are proposed, usually by members of the appropriate IAU Working Group. However, there is no guarantee that the name will be accepted.

Names reviewed by an IAU Working Group are submitted by the group's chairperson to the Working Group for Planetary System Nomenclature (WGPSN). After this, the members of the WGPSN vote on the names.

The names approved by the WGPSN members are considered as official IAU nomenclature and can be used on maps and in publications. The approved names are then entered into the Gazetteer of Planetary Nomenclature, and posted on the website of IAU.


If there are any objections to the proposed names, an application has to be sent to the IAU general secretary within three months from the time the name was placed on the website. The general secretary will make a recommendation to the WGPSN Chair as to whether or not the approved name(s) should be reconsidered.

 In 1966, the Outer Space Treaty was formed by the United Nations Office for Outer Space Affairs to set rules for international space law. One of the key aspects of this treaty was that the outer space, including the moon and other celestial bodies, shall be free for exploration and use by all states without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.

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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 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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When did Voyager 2 achieve its closest approach to Jupiter?

On July 9, 1979, Voyager 2 made its closest approach to the largest planet in our solar system. Now in interstellar space. Voyager 2 altered some of our ideas about the Jovian system.

The Voyager probes are: humanity's longest running spacecraft as they have been flying since 1977 Both Voyager 2 and Voyager 1 are now in interstellar space, and though their power sources are gradually fading, they are still operational as of now.

It might seem counter-intuitive, but Voyager 2 was the first to be launched on August 20, 1977-about two weeks before the launch of Voyager 1. Both spacecraft were equipped with an extensive array of instruments to gather data. about the outer planets and their systems, in addition to carrying a slow-scan colour TV camera capable of taking images of the planets and their moons.

Based on Mariners

The design of the Voyagers was based on the Mariners and they were even known as Mariner 11 and Mariner 12 until March 7. 1977. It was NASA administrator James Fletcher who announced that the spacecraft would be renamed Younger. The Voyagers are powered by three plutonium dioxide radioisotope thermoelectric generators (RTGS) mounted at the end of a boom (a long metal beam extending from the spacecraft and serving as a structure subsystem).

Even though Voyager 1 was launched a little later, it reached Jupiter first in 1979 as it took a trajectory that put it on a faster path. Voyager 2 began transmitting images of Jupiter from April 24, 1979 for time-lapse movies of atmospheric circulation. For the next three-and-a-half months, until August 5 of that year, the probe continued to click images and collect data. A total of 17,000 images of Jupiter and its system were sent back to the Earth.

The spectacular images of the Jovian system included those of its moons Callisto, Europa, and Ganymede. While Voyager 2 flew by Callisto and Europa at about half the distance between the Earth and its moon, it made an even closer approach to Ganymede.

Ocean worlds

The combined cameras of the two Voyager probes, in fact. covered at least four-fifths of the surfaces of Ganymede and Callisto. This enabled the mapping out of these moons to a resolution of about 5 km.

Voyager 2's work, along with observations made before and after, also helped scientists reveal that each of these moons were indeed an ocean world.

On July 9, 1979, the probe made its closest approach to Jupiter. Voyager 2 came within 6,45,000 km from the planet's surface, less than twice the distance between Earth and its moon. It detected many significant atmospheric changes, including a drift in the Great Red Spot in addition to changes in its shape and colours.

Voyager 2 also relayed photographs of other moons like lo and Amalthea. It even discovered a Jovian satellite, later called Adrastea, and revealed a third component to the planet's rings. The thin rings surrounding Jupiter, as had been seen by Voyager 1 as well, were confirmed by images looking back at the giant planet as the spacecraft departed for Saturn. As the probe used the gravity assist technique, Jupiter served as a springboard for Voyager 2 to get to Saturn.

Studies all four giant planets

 Four decades after its closest approach to Jupiter, Voyager 2 successfully fired up its trajectory correction manoeuvre thrusters on July 8, 2019. These thrusters, which had themselves last been used only in November 1989 during Voyager 2's encounter with Neptune, will be used to control the pointing of the spacecraft in interstellar space.

In those 40 years, Voyager 2 had achieved flybys of Saturn (1981), Uranus (1986), and Neptune (1989), thereby becoming the only spacecraft to study all four giant planets of the solar system at close range. Having entered interstellar space on December 10, 2018, Voyager 2 is now over 132 AU (astronomical unit-distance between Earth and the sun) away from the Earth, still relaying back data from unexplored regions deep in space.

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Why isn't there an sound in space?

"In space, no one can hear you scream." You may have heard this saying. It's the tag line from the famous 1979 science fiction movie "Alien." It's a scary thought, but is it true? The simple answer is yes, no one can hear you scream in space because there is no sound or echo in space. I'm a professor of astronomy, which means I study space and how it works. Space is silent – for the most part.

How sound works

To understand why there's no sound in space, first consider how sound works. Sound is a wave of energy that moves through a solid, a liquid or a gas. Sound is a compression wave. The energy created when your vocal cords vibrate slightly compresses the air in your throat, and the compressed energy travels outward.

A good analogy for sound is a slinky toy. If you stretch out a Slinky and push hard on one end, a compression wave travels down the Slinky. When you talk, your vocal cords vibrate. They jostle air molecules in your throat above your vocal cords, which in turn jostle or bump into their neighbours, causing a sound to come out of your mouth.

Sound moves through air the same way it moves through your throat. Air molecules near your mouth bump into their neighbours, which in turn bump into their neighbours, and the sound moves through the air. The sound wave travels quickly, about 1,223 kilometres per hour, which is faster than a commercial jet

 Sound in the solar system

Scientists have wondered how human voices would sound on our nearest neighbouring planets. Venus and Mars. This experiment is hypothetical because Mars is usually below freezing, and its atmosphere is thin. unbreathable carbon dioxide. Venus is even worse - its air is hot enough to melt lead, with a thick carbon dioxide atmosphere.

On Mars, your voice would sound tinny and hollow, like the sound of a piccolo On Venus, the pitch of your voice would be much deeper, like the sound of a booming bass guitar.The reason is the thickness of the atmosphere. On mars the thin air creates a high-pitched sound,and on venus the thick air creates a low-pitched sound. The team that worked this out simulated other solar system sounds, like waterfall on saturn’s moon titan.

Deep space sounds

While space is a good enough vacuum that normal sound can't travel through it, it's actually not a perfect vacuum, and it does have some particles floating through it. Beyond the Earth and its atmosphere, there are five particles in a typical cubic centimetre - the volume of a sugar cube- that are mostly hydrogen atoms.

By contrast, the air you are breathing is 10 billion billion (1019) times more dense. The density goes down with distance from the Sun, and in the space between stars there are 0.1 particles per cubic centimetre. In vast voids between galaxies, it is a million times lower still fantastically empty.

The voids of space are kept very hot by radiation from stars. The very spread-out matter found there is in a physical state called a plasma. A plasma is a gas in which electrons are separated from protons. In a plasma, the physics of sound waves get complicated. Waves travel much faster in this low-density medium, and their wavelength is much longer.

In 2022, NASA released a spectacular example of sound in space. It used X-ray data to make an audible recording that represents the way a massive black hole stirs up plasma in the Perseus galaxy cluster, 250 million light years from Earth. The black hole itself emits no sound, but the diffuse plasma around it carries very long wavelength sound waves.

The natural sound is far too low a frequency for the human ear to hear, 57 octaves below middle C which is the middle note on a piano middle of the range of sound people can hear. But after raising the frequency to the audible range, the result is chilling - it's the sound of a black hole growling in deep space.

Space is a vacuum

So what about in space? Space is a vacuum, which means it contains almost no matter. The word vacuum comes from the Latin word for empty. Sound is carried by atoms and molecules, In space, with no atoms or molecules to carry a sound wave, there's no sound. There's nothing to get in sound's way out in space, but there's nothing to carry it, so it doesn't travel at all. No sound also means no echo. An echo happens when a sound wave hits a hard, flat surface and bounces back in the direction it came from By the way, if you were caught in space outside your spacecraft with no spacesuit, the fact that no one could hear your cry for help is the least of your problems. Any air you still had in your lungs would expand because it was at higher pressure than the vacuum outside. Your lungs would rupture. In a mere 10 to 15 seconds, you'd be unconscious due to a lack of oxygen.

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Why does the European Space Agency want to give the Moon its own time?

The European Space Agency announced that space organisations around the world are considering how best to keep time on the moon. The need is for an internationally accepted lunar time zone.

How do you keep track of time on the moon?  What is the lunar reference point? The moon needs to be given its own time zone, the European Space Agency announced recently. As the race to the moon begins and more and more lunar missions are getting deployed, it is become, pertinent to come with a common refer time.

The European Space Agency announced that space organisations and the world are considering how best to keep time on the moon. The idea took out at a meeting in the Netherlands last year in such the participants agreed on the imminent need to set up    “ a common lunar reference time” Pietro Giordana, a navigation system engineer of the space agency said.

“A joint international effort is now being launched towards achieving this, “Giordano said in a statement.

As of now, a moon missions on the time of the country that is operating the spacecraft. The need is for an internationally accepted lunar time zone. This will be easier for all space-faring nations as mare countries and even private companies are aiming for the moon. The NASA is also getting art to send astronauts there.

 The question of time confounded NASA as it was designing and building the international Space Station, fast approaching the 25th anniversary of the launch of its first pierce. The space station doesn’t have its a time zone, But it runs on Coordinated Universal Time, or UTC which is meticulously based on atomic clocks. This ensures in splitting the time difference between NASA and the Canadian Space Agency, and the other partnering space programmes in Russia, Japan and Europe.

Debate is going on among the international team looking into lunar time on whether a single organisation should set and maintain time on the moon.

When it comes to keeping time on the moon, there are technical issues involved. One being that clocks run faster on the moon than on Earth, gaining about 56 microseconds each day, according to the space agency. Also, ticking occur differently on the lunar surface than in bar orbit.

The lunar time will have to be practical for astronauts there, noted the space agency’s Bernhard Hufenbach. NASA is gearing up for its first flight to the moon with astronauts in more than a half-century in 2024, with a lunar landing as early as 2025.

“This will be quite a challenge” with each day lasting as long as 29.5 Earth days, Hufenbach said in a statement. “But having established a working time system for the moon, we can go on to do the same for other planetary destination.” Mars standard Time, anyone?

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What is the mysterious object in the James Webb telescope?

A team of international astrophysicists has discovered many mysterious objects that were hidden in images from the James Webb Space Telescope. These include six potential galaxies that should have emerged so early in the history of the universe and are so massive that they should not be possible under current cosmological theory.

These candidate galaxies may have existed roughly 500 to 700 million years after the Big Bang. That places them at more than 13 billion years ago, close to the dawn of the universe. Containing nearly as many stars as the modern-day Milky Way, they are also gigantic. The results of the study have been published in the journal Nature in February

Not the earliest discovered

 Launched in December 2021, the James Webb Space Telescope is the most powerful telescope ever sent into space by us. The candidate galaxies identified this time from its data, however, aren’t the earliest galaxies observed by Jams Webb. Another group of scientists spotted four galaxies observed that likely formed 350 million years after the Big band. Those galaxies, however, were nowhere as massive as the current findings.

While looking at a stamp-sized section of an image that looked deep into a patch of sky close to the Big Dipper (a constellation, also known as the Plough), a researcher spotted fuzzy dots that were way too bright and red. In astronomy, red light usually equals old light. As the universe expands the light emitted by celestial objects stretches, making it redder to human instruments.

Based on their calculations, the team was also able to suggest that the candidate galaxies they had discovered were also huge. Containing tens to hundreds of billions of sun-sized stars worth of mass, these were akin to our Milky Way.

Might rewrite astronomy books

As current theory suggests that there shouldn't have been enough normal matter at that time to form so many stars so quickly, proving it might rewrite astronomy books. And even if these aren't galaxies, then another possibility is that they are a different kind of celestial object, making them interesting.

For now, the discovery has piqued the interest of the researchers and the astronomical community. More data and information about these mysterious objects from James Webb is what is being sought after to confirm that these candidate galaxies are actually as big as they look, and date as far back in time.

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How about learning a bit about the stellar world?

Every star is a giant, bright ball of hot gas. Ever wondered how the stars form and how they die eventually? How about learning a bit about the stellar world?

One septillion stars, that’s almost the number of stars estimated to exist in our universe, Our Milky Way alone contains more than 100 billion stars. The nearest star to us is our Sun. Every star is a giant ball of hot gas. They are the building block of galaxies. "We are made of star stuff,” said noted astronomer Carl Sagan. It means that whatever we are composed of whatever our physical bodies are made of the raw materials that make up our physical bodies were created from the matter from long-extinguished stars. How about learning a bit about the stellar world?

Stars and their birth

Stars are made of huge balls of hot gas it is largely composed of hydrogen and small parts of helium and a few other elements. The star is held together because of its own gravity.

Every star goes through its own unique life cycle. Stars are born within hinge clouds of dust and gas called molecular clouds and are scattered throughout the galaxies. The gas in the molecular clouds clump together, forming high-density pockets, and often collide with each other. With each collision, more matter gets added to it and its mass grows. The gravitational force becomes stronger. The clumps of gas and dust then collapse under their own gravitational attraction. As this happens, the material heats up because of the friction and leads to the formation of a protostar which is also called the baby star. The set of stars newly formed from molecular clouds are called stellar clusters.

Life of a star

The energy of a protostar is derived from the heat released by its initial collapse. As years pass by, the high pressure and temperature inside the core of the star lead to a nuclear fusion reaction, where the nuclei of hydrogen atoms combine together to form helium. The energy that gets released post-nuclear fusion is enough to prevent it from collapsing under gravity.

At any time, there are two opposing forces acting on a star that prevent it from collapsing. There is the gravity of the star which tries to shrink the star, while the energy released following the nuclear fusion in the stars core leads to outward pressure. This outward push will resist gravity's inward squeeze.

When a star is in the phase of undergoing a nuclear fusion reaction, it is called a main sequence star. This is also the longest phase of the star’s life. It has to be noted that as time passes, that is over millions of years, the size, luminosity and temperature of the star also change. The gas in the star is its fuel and its mass determines how long the star will live. This is because a massive star will end up burning a lot of fuel at a higher rate to generate enough energy to prevent it from collapsing: Meanwhile, lower mass stars will burn longer and shine for longer periods, some trillions of years whilst the massive ones may live for just about a few million years.

How does a star die?

When the star runs out of hydrogen to convert into helium, it marks the beginning of the end of the star’s life. Its core collapses leading to the death of the star. A star’s death is largely dependent on its mass. In the case of a lower-mass star, its atmosphere will keep on expanding until it becomes a giant star and the helium gets converted into carbon in its core. Over time the outer layers of the star will get blown off and the cloud of gas and dust expands. This expanding cloud is called a planetary nebula. All that is left now is the core. This is called a white dwarf star which will cool off over the following billions of years.

But what happens in the case of a high-mass star? The fusion leads to the conversion of carbon into heavier elements which then fuel the core. This process produces enough energy to prevent the core from collapsing. This goes on for a few million years until the star runs out of fuel. This is followed by a supernova explosion. The core either becomes a neutron star or a black hole

The supernova explosion is the biggest explosion that occurs in space. It releases material into the cosmos and this matter will then form part of the future molecular clouds and thereby become part of the stars.

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What’s the great Attractor?

In the depths of the cosmic ocean, there is a strange force that keeps pulling our galaxy towards it. And inevitably, whatever is near our Milky Way, including nearby galaxies, are being drawn towards this unknown force.

But for the longest time, we couldn't understand what was the cause of this force or what lay here as this portion of the universe where the attraction is being felt is hidden from our view all thanks to our own galaxy. The force that is pulling the Milky Way lies in the direction of the constellation Centaurus. And the Milky Way's disk blocks out our view here.

This region, which we can't look through (with telescopes) from our galaxy, has been called the Zone of Avoidance. And the Great Attractor sits right here, at this 20% of the universe that's shielded from us.

The only way to get a glimpse of this area is by using X-rays and infrared light.

It was in the 1970s that the Great Attractor was first discovered. It happened when astronomers made detailed maps of the Cosmic Microwave Background (that is, the light left over from the early universe). It was observed that one side of the Milky Way was warmer than the other.

This indicated that the galaxy was vigorously moving through space. The speed was observed to be about 370 miles per second (600 km/s). While astronomers could measure the high speed at which the galaxy was moving, they couldn't explain its cause or origin.

The Great Attractor is a region of great mass that exerts an immense gravitational pull on our galaxy and surrounding galaxies. It is estimated to have a diameter of about 300 million light-years. It is estimated to be between 150 and 250 million light years away from Earth.

It sits at the centre of a local Supercluster known as the Laniakea Supercluster.

In short, the Great Attractor is the gravitational centre of the Laniakea Supercluster which consists of our galaxy and 100,000 others.

It is not a celestial body, but rather a point in the universe where everything gets attracted to.

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What is a planet beyond our solar system called?

A planet beyond our own solar system is referred to as an exoplanet. While most exoplanets orbit other stars, there are also free-floating exoplanets, called rogue planets, that are not tethered to any star and orbit the galactic centre.

"Blind" surveys

Traditionally, ground-based means have been employed to detect exoplanets. Astronomers use "blind" surveys to look for stars in the sky with the potential for housing giant planets, which can then be directly imaged from Earth based on the stars age and distance. This technique, however, has a very low yield, meaning that exoplanets are detected very infrequently. Astronomers have developed a new technique to detect exoplanets whose portraits can be taken using large ground-based telescopes on Earth. They have tasted success with this method and the result is the direct image of a Jupiter-like gas giant - HIP 99770 b-132.8 light years away in the Cygnus constellation. The study behind this success was published in the journal Science in April.

Combining astrometry and direct imaging

HIP 99770 b is the first exoplanet detected by combining astrometry and direct imaging. While two observatories on Hawaii Island did the direct imaging, the astrometry- responsible for measuring the position and motion of HIP 99770 b's home star - came from Gaia space observatory and its predecessor Hipparcos.

Precision astrometry is the method of detecting the movement of stars. This allows researchers to identify those stars that are tugged at by the gravitational pull of an unseen companion like a planet. A picture of the star systems that are close enough is then captured to directly image.

The detection of HIP 99770 b serves as proof of a concept developed by an international research team. They were also able to determine that this exoplanet is 14-16 times the mass of Jupiter and orbits a star that is almost twice as massive as our sun. It receives a similar amount of light as Jupiter as its host star is far more luminous than the sun. The team characterised the nature of HIP 99770 b's atmosphere and showed that the planet's atmosphere has signs of water and carbon monoxide.

This new method of searching for exoplanets is believed to be a major improvement to the existing, traditional method of "blind" surveys. The researchers also hope that this new approach would lead to further advances that eventually lead to the discovery of an Earth-twin around a nearby star.

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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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