Mission Aditya L1: ISRO’s Extraordinary solar Mission 

Introduction  

After a historic achievement in mission Chandraayan 3, now ISRO launched a new mission called Aditya L1. In this mission ISRO is going to the Sun. Sun is our closest star and main part of our solar system. So, it is important to understand the behavior of the sun.  Well, ISRO is not the first space agency to study sun. In the past there were three more agencies (NASA, ESA, JAXA) have conducted a space mission to study the sun.

Aditya L1 is the first space mission of India to study the Sun. This mission can be a historical achievement of India and ISRO. Aditya L1 travel 1.5 million kms (about 932056.79 mi) away from earth which is 1% of earth – sun distance. This mission timeline is around 5 years. Aditya L1 will continuously study sun behavior for the next five years.  But what is the uniqueness of this mission? What are the objectives of this mission? What will Aditya L1 do in space? A lot of questions! Right? Let’s check out everything in detail.  

Why is ISRO going to sun? 

There are four objectives of Mission Aditya L1 to get a deeper understanding of the sun. The first one is Coronal heating and solar wind acceleration. Second is Coupling and dynamics of the solar atmosphere, third is Solar wind distribution and temperature anisotropy and the fourth is Initiation of Coronal Mass Ejection (CME), flares, and near-earth space weather.  

In these four objectives most important are two. Let’s dive deep into it.   

(1) Coronal heating 

The mystery of coronal heating is 150 years old. So, what is coronal heating? Same as earth, Sun also has layers. The photosphere, which is about 500kms (about 310.69 mi) above and with temperature of 6000-degree C. After that there is another layer called Chromosphere, which is Around 1500 to 5000 kms and 10000 degree C temperature. And the last outer layer which is called corona. This layer is very huge. Infect you can fit 400 earths in this layer. But the shocking fact about this layer is its temperature. Corona has 1-million-degree C temperature. Shocking right? 

Well in our science classes, we have learned in thermodynamics that when we go far from the heat source the temperature gets decrees. But in the sun, it’s totally the opposite. When you go far from the sun core the temperature increases dramatically. Well from the last 150 years scientists are finding the reasons behind this mystery that why sun outer layer has the highest temperature. So, Aditya L1 will help ISRO to understand this mysterious behavior of the sun.  

(2) Coronal Mass Ejection (CME) 

CME is also known as Solar Strome. This is a very serious topic. Because this is very dangerous for us. Let’s understand what Coronal Mass Ejection is? In the coronal layer, a huge amount of strength and magnetic field suddenly changes direction creating a loophole of solar plasma and magnetic field.  Corona releases these loopholes with speed of 6000km (about 3728.23 mi)/h. These loopholes are very distractive. Anything that comes in their path will melt in seconds. Sun creates a lot of solar storms in space. Which are very dangerous.  

In the past, solar Strome already came on earth.  That solar Strome caused a radio blackout in some areas of US and Pacific Ocean. Recently, 40 satellites from star link destroyed by solar Strome in space. So, it is very important to prevent them. Well, we cannot stop them for now, but we can predict them. So, Aditya L1 will help us to estimate the CME. Aditya L1 will help us to predict a solar storm like when they will reach? What is strength? Will they come to earth or not? will they affect our satellites etc. 

Launch and Trajectory path for Aditya L1 

Aditya L1 Launched by PSLV – C57 rocket on 2 September 2023 from second launch pad of Satish Dhavan Space Center, Shrihari Kota. This rocket was programmed to launch space craft to earth bond orbit. The spacecraft will orbit earth for the next 16 days (about 2 and a half weeks). When it reaches pedigree of last orbit then final thruster will be fired. And spacecraft will be released from earth orbit like sling shot.  

After that the engines will stay on, and spacecraft will start the journey towards the sun. This is also called the cruise phase. Because the distance to travel is about 1.5 million kms (about 932056.79 mi). Which is very far and that’s why spacecraft will take 127 days (about 4 months) to reach L1 point (Lagrange point). We will see about this L1 point later in this article. Well unlike other satellites Aditya L1 will not orbit the sun. But Aditya L1 will stay in static position on L1 point. Which is very challenging.

So, make satellite stay on one position it will start HALO Orbit Intergen. For that spacecraft will take turn to reduce speed and enter into orbit of L1 point.  

Why L1 point? 

Now the question is why L1 point? L1 point is Lagrange point. At this point the gravity of earth and sun counter each other. So, the object can stay steady at this point. So, between sun and earth, there are a total of five Lagrange points. L1, L2, L3, L4 and L5. These are all points where the earth and sun’s gravity counter each other. But why only L1. 

L2 point is opposite of the sun so we cannot observe the sun properly. L3 is very far from earth which will cause communication problems. L4 and L5 are the most stable points but because of their stability there are so many asteroids moving which can destroy the spacecraft. For this reasons L1 is the perfect point to study sun.  

But putting the spacecraft Steady at this point is very challenging. There are three problems at L1 point. L1 point is not that stable. During the insurge if earth gravity increases spacecraft will start orbiting earth which is not the mission. Second is if sun gravity increases the spacecraft will start orbiting sun which is also not a mission. And the third problem is spacecraft can be lost in space during the insurge. So, scientists decided to make spacecraft orbit the L1 point. And this imaginary orbit is called HALO Orbit.  

Payloads on Aditya L1 

There are seven payloads available on Aditya L1 to study sun. Let’s check out each one properly.  

VELC (Visible Emission Line Coronagraph) 

VELC is the prime payload designed as a reflective coronagraph with a multi-slit spectrograph. It is designed to study solar corona and dynamics of coronal mass ejections. The payload is developed by Indian Institute of Astrophysics, Bengaluru in close collaboration with ISRO. 

SUIT (Solar Ultra-violet Imaging Telescope) 

SUIT is a UV telescope to image the solar disk in the near ultra-violet wavelength range. SUIT is designed to image the Solar Photosphere and Chromosphere in near Ultra-violet (UV) and, to measure the solar irradiance variations in near UV. The payload is developed by Inter University Centre for Astronomy and Astrophysics, Pune in close collaboration with ISRO. 

SoLEXS (Solar Low Energy X-ray Spectrometer) 

SoLEXS is a soft X-ray spectrometer designed to measure the solar soft X-ray flux to study solar flares. Main scientific aims of this payload are study coronal and flares heating, study the source of coronal heating, flare and coronal mass ejection. This payload is developed at U R Rao Satellite Centre, Bengaluru. 

HEL1OS (High Energy L1 Orbiting X-ray Spectrometer) 

HEL1OS is a hard X-ray spectrometer designed to study solar flares in high energy X-rays. This payload is designed to study the phenomena of solar flares. Developed at U R Rao Satellite Centre, Bengaluru. 

ASPEX (Aditya Solar wind Particle Experiment) 

There are two parts of this payload. SWIS and STEPS. SWIS, also known as Solar Wind Ion Spectrometer, is a low-energy spectrometer designed to measure the proton and alpha particles of the solar wind. Supra thermal and Energetic Particle Spectrometer (STEPS) is a high-energy spectrometer designed to measure high-energy ions of the solar wind. ASPEX is developed at Physical Research Laboratory, Ahmedabad. 

PAPA (Plasma Analyzer Package for Aditya) 

PAPA is designed to understand solar winds and its composition and do mass analysis of solar wind ions. PAPA is developed at Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram. 

MAG (Magnetometer) 

MAG will measure the low intensity interplanetary magnetic field in space. It has two sets of Magnetic Sensors: one at the tip of a 6-meter deployable boom, and the other in the middle of the boom, 3 meters away from the spacecraft. The main objective of this payload is to measure magnitude and direction of magnetic field, study solar events like coronal mass ejection, impact of solar events near earth and study solar plasma and solar wind near L1 point. payload can measure interplanetary magnetic fields at the L1 point. The payload is developed at Laboratory for Electro Optics Systems, Bengaluru. 

Limitations of Mission Aditya L1 

Well, this is a huge achievement of ISRO. ISRO is going to explore the sun for the first time. Very proud moment for India and ISRO. And we all know the success of Chandrayan 3. So, this mission Aditya L1 will also break records. But there are some limitations for this mission which are confirmed by ISRO itself.  

The first is, due to weight limits of PSLV rocket ISRO could not fit the most advanced instruments in the spacecraft. The second is spacecraft will study the sun from L1 point only. We will not able so other sides of the sun. We will be only facing the side from L1 point. The third is poles of sun. behind magnetic field of sun and coronal mass ejection, the main role is poles of sun. To study the poles of sun we must put satellite in vertical orbit which is technically very challenging.  

Conclusion 

 Well, I know, ISRO will get success in this mission. Aditya L1 will study the sun for 5 years and send us information about the sun. We will find the reason behind the coronal heating, coronal mass ejection, behavior of sun, space weather, etc. Only one mission will not justify the study of the sun. We need to do more missions in future. And ISRO is ready for that. ISRO has planned so many space missions in the future.  

Thanks for reading this article until here. If you like this article, then you would like this one also. Check out the articles on Chandrayaan 3 and LUNA 25.  

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References

• https://en.wikipedia.org/wiki/Aditya-L1 
• https://www.isro.gov.in/Aditya_L1_Payload.html