Aditya-L1: India set to launch its first mission to Sun

By Geeta Pandey
BBC News, Delhi
India is set to launch its first observation mission to the Sun, just days after the country made history by becoming the first to land near the Moon's south pole.

Aditya-L1 is due to blast off from the launch pad at Sriharikota on Saturday at 11:50 India time (06:20GMT).

It will be located at a distance of 1.5 million km (932,000 miles) from the Earth - 1% of the Earth-Sun distance.

India's space agency says it will take four months to travel the distance.

India's first space-based mission to study the solar system's biggest object is named after Surya - the Hindu god of Sun who is also known as Aditya.

And L1 stands for Lagrange point 1 - the exact place between Sun and Earth where the Indian spacecraft will be placed.

According to the European Space Agency, a Lagrange point is a spot where the gravitational forces of two large objects - such as the Sun and the Earth - cancel each other out, allowing a spacecraft to "hover".

Once Aditya-L1 reaches this "parking spot", it would be able to orbit the Sun at the same rate as the Earth. This also means the satellite will require very little fuel to operate.

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The Indian Space Research Agency (Isro) says once the spacecraft takes off, it will travel several times around the Earth before being launched towards L1.

From this vantage position, Aditya-L1 will be able to watch the Sun constantly - even when it's hidden like during an eclipse - and carry out scientific studies.

The Indian Space Research Agency (Isro) has not said how much the mission would cost, but reports in the Indian press put it at 3.78bn rupees ($46m; £36m).

sro says the orbiter carries seven scientific instruments that will observe and study the solar corona (the outermost layer); the photosphere (the Sun's surface or the part we see from the Earth) and the chromosphere (a thin layer of plasma that lies between the photosphere and the corona).

The studies will help scientists understand solar activity, such as solar wind and solar flares, and their effect on Earth and near-space weather in real time.

Former Isro scientist Mylswamy Annadurai says the Sun constantly influences the Earth weather through radiation, heat and flow of particles and magnetic fields. At the same time, he says, it also impacts the space weather.

"Space weather plays a role in how effectively the satellites function. Solar winds or storms can affect the electronics on satellites, even knock down power grids. But there are gaps in our knowledge of space weather," Mr Annadurai told the BBC.

India has more than 50 satellites in space and they provide many crucial services to the country, including communication links, data on weather, and help predict pest infestations, droughts and impending disasters. According to UN's Office for Outer Space Affairs (UNOOSA), approximately 10,290 satellites remain in Earth's orbit, with nearly 7,800 of them currently operational.

Aditya, says Mr Annadurai, will help us better understand, and even give us a forewarning, about the star on which our lives depend.

"Knowing the activities of the Sun such as solar wind or a solar eruption a couple of days ahead will help us move our satellites out of harm's way. This will help increase the longevity of our satellites in space."

The mission, he adds, will above all help improve our scientific understanding of the Sun - the 4.5 billion-year-old star that holds our solar system together.

India's solar mission comes just days after the country successfully landed the world's first-ever probe near the lunar south pole.

With that, India also became only the fourth country in the world to achieve a soft landing on the Moon, after the US, the former Soviet Union and China.

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If Aditya-L1 is successful, India will join the select group of countries that are already studying the Sun.

Japan was the first to launch a mission to Sun in 1981 to study solar flares and the US space agency Nasa and European Space Agency (ESA) have been watching the Sun since the 1990s.

In February 2020, Nasa and ESA jointly launched a Solar Orbiter that is studying the Sun from close quarters and gathering data that, scientists say, will help understand what drives its dynamic behaviour.

And in 2021, Nasa's newest spacecraft Parker Solar Probe made history by becoming the first to fly through corona, the outer atmosphere of the Sun.