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| Credit: ISRO |
The Sun, our closest Star and largest body in our solar system, is quite far away at about 93 million miles from Earth. The outer part of the sun that we can see, called the photosphere, is not super-hot and still has a temperature of roughly 5,500°C. This big, fiery ball has been lighting up our world for about 4.5 billion years. It's mainly made up of hydrogen (which is about 74% of its stuff) and helium (which is around 24%). Deep inside, the Sun does something amazing called nuclear fusion. It's like a never-ending hug between hydrogen atoms, which creates helium and releases a lot of light and warmth that keep our solar system going.
MAIN SCIENTIFIC GOALS:
- Grasping the concept of heating, the Sun's outer layer and speeding up process of solar wind.
- Unraveling how Coronal Mass Ejections (CMEs), flares, and space weather near Earth begin.
- Comprehending how the solar atmosphere connects and moves.
- Exploring the distribution of solar wind and temperature differences.
• First instance of capturing detailed images of the solar surface in the nearby ultraviolet range.
• CME dynamics close to the solar disk (~ from 1.05 solar radius) thereby providing information on the acceleration regime of CME which is not observed consistently.
• Smart systems onboard to identify Coronal Mass Ejections (CMEs) and solar flares, leading to better observations and data management.
• Studying the solar wind's direction and energy differences through observations from multiple angles.
WHY LEARN ABOUT THE SUN?
The sun is like our closest star in space, and because of that, we can study it really well compared to other faraway stars. When we learn about the sun, we also get to know a lot about the stars in our Milky Way galaxy and even stars in different galaxies. The sun is an active star that's way bigger than it looks. It does things like bursts and releases a huge amount of energy in space. If these bursts point toward Earth, they can cause problems for satellites and communication systems. It's important to know about these bursts beforehand so we can be ready. And if astronauts ever got caught in these bursts, it could be dangerous. Therefore, gaining a more accurate understanding of these bursts will be beneficial for our upcoming journeys with astronauts to space. The sun also helps us understand some really powerful heat and magnetic stuff that's hard to study in a regular lab. So, it's like a natural lab for scientists to figure out things they can't usually study up close.
THE EVOLVING WHEATHER OF SPACE
The sun is always affecting Earth with its energy, heat, and particles, along with magnetic fields. These particle streams from the sun are called solar wind and they're made mostly of supercharged protons. Solar wind fills up almost all the space in our solar system. The sun's magnetic field does too. When the solar wind combines with big bursts from the sun, like Coronal Mass Ejections (CMEs), it changes space around us. This shift can mess with the magnetic and charged particle environment nearby. On Earth, when a CME's magnetic field interacts with our magnetic field, it can cause a magnetic shakeup. This can mess with the stuff we have in space, like satellites & space stations. We call the changing space conditions around Earth and other planets "space weather." Since we're using more and more space tech, it's really important to understand space weather. Plus, studying Earth's space weather helps us figure out what happens on other planets too.
ADITYA-L1 MISSION || India's Inaugural Observatory-Style Solar Mission in Space
"Aditya L1 marks India's initial space mission for solar research, aiming to study the Sun. This spacecraft will go into a special orbit around a point between the Sun and Earth, about 1.5 million km away from Earth, called Lagrangian Point 1 (L1). The cool thing about this orbit is that it lets the spacecraft always see the Sun without anything blocking its view. This means it can keep an eye on the Sun's activities all the time. The spacecraft has seven scientific payloads on board to look at different parts of the Sun, from the surface to the outer layers called the “Corona”. These payloads use things like waves and particles to study the Sun. Some of them look right at the Sun, while others check the space around L1. The tools will give us a lot of important information, like why the Sun's outer layer is so hot, how things like solar storms happen, and how particles and fields move in space between planets, etc."
PAYLOADS IN DETAIL:
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| Credit: ISRO |
The Aditya-L1 mission carries a set of seven scientific tools to conduct a thorough examination of the Sun. The Visible Emission Line Coronagraph (VELC) observes the Sun's outer layer and the movements of big solar bursts. The Solar Ultra-Violet Imaging Telescope (SUIT) takes pictures of the Sun's surface and its atmosphere in near Ultra-violet light. It also measures changes in the Sun's brightness in this light. The Aditya Solar Wind Particle Experiment (ASPEX) and Plasma Analyser Package for Aditya (PAPA) will observe the solar wind and the energetic particles it carries, including how their energy is spread out. The Solar Low Energy X-ray Spectrometer (SoLEXS) and The High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) study powerful X-ray flashes from the Sun across a wide range of X-ray types.
The Magnetometer tool can measure magnetic fields between planets at the L1 point. All of these payloads and technologies are made by different labs in India. The VELC comes from the Indian Institute of Astrophysics in Bangalore. The SUIT is made by the Inter-University Centre for Astronomy & Astrophysics in Pune. The ASPEX comes from the Physical Research Laboratory in Ahmedabad. The PAPA is from the Space Physics Laboratory at Vikram Sarabhai Space Centre in Thiruvananthapuram. The SoLEXS and HEL1OS are from U R Rao Satellite Centre in Bangalore, and the Magnetometer is from the Laboratory for Electro-Optics Systems in Bangalore. All these tools are made in partnership with different parts of ISRO.
LAGRANGE POINTS
In a system where two big objects are held together by gravity, there are certain spots in space where a smaller object can stay without floating away. These spots are called “Lagrange Points”. These points can be useful for spacecraft because they can park there using less fuel. When you're at a Lagrange Point, the pull from the big objects balances out with the force needed to keep a smaller thing moving with them. There are five of these points for systems with two big objects, like the Sun and Earth. They're labeled as follows; L1, L2, L3, L4, and L5. In the Sun-Earth system, the points are shown in a picture. L1 sits between the Sun and Earth in a straight line. It's about 1% of the distance between Earth and the Sun.
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| Credit: ISRO |
At first, the spacecraft will go into a low orbit around Earth. Then, its orbit will change to be more oval-shaped. Later, the spacecraft will be sent towards Lagrange point L1 using its own engines. As it heads to L1, it will leave the part of space where Earth's gravity is strong. Once it's out of that area, it will start a smooth journey and eventually settle into a big curved orbit around L1. The whole trip from launch to L1 will take about four months for Aditya-L1. You can see the path the Aditya-L1 mission will take in the picture above.
Does Aditya-L1 Cover All Aspects of Sun Study?
The straightforward answer is 'NO,' and this goes for not just Aditya-L1 but all space missions in general. Because the spacecraft that carries the scientific tools in space has limits on how much stuff it can take—like weight, power, and space. So, it can only carry a certain number of instruments with certain abilities. In the case of Aditya-L1, it's focusing on taking measurements from Lagrange point L1. However, there's a catch. The sun has lots of different things happening in different directions. But with just Aditya-L1, we can't look at all directions of things like big bursts. There's another Lagrange point, L5, which is a good spot to study solar events headed towards Earth and check space weather. Plus, the sun's polar areas haven't been studied much because it's hard to get spacecraft there. These areas matter because they might affect the sun's cycles. We also need to measure sunlight's polarization in different colors to understand the things happening in and around the sun.
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