Maarg Manthan · Topic 12.8

Solar Mission Aditya-L1

Science & Technology › Space Technology and ISRO · Topic 12.8

Aditya-L1 is India's first space-based observatory to study the Sun, launched by PSLV-C57 from Sriharikota on 2 September 2023. After a journey of about four months, it was placed in a halo orbit around the first Sun-Earth Lagrange point, L1, on 6 January 2024. L1 lies about 1.5 million kilometres from the Earth towards the Sun, about one per cent of the Earth-Sun distance, and a spacecraft there can watch the Sun all the time without eclipses. Aditya-L1 carries seven payloads to study the corona, the photosphere, the chromosphere, solar flares, the solar wind and the magnetic field of the Sun, and its planned life is five years.

5 min read · UPSC Prelims · Science & Technology · Space Technology and ISRO

At a Glance

Launched 2 September 2023, PSLV-C57
Reached L1 orbit 6 January 2024
Distance About 1.5 million km
Payloads Seven
Planned life Five years
Exam link UPSC Prelims, Science & Technology: Space Technology and ISRO

Where Does It Fit?

This topic follows the account of Chandrayaan and Mars missions. After the Moon and Mars, India turned to the Sun, and Aditya-L1 uses the Lagrange point idea that was introduced earlier in the macro on astrophysics. Previous topic: Chandrayaan Missions (Chandrayaan-I, II, III) and the Mars Orbiter Mission. Next topic: NASA, ESA, Roscosmos, JAXA and CNSA Space Missions.

What Does Aditya-L1 Carry and Study?

Payload	What it observes
Visible Emission Line Coronagraph (VELC)	The main payload. Blocks the Sun’s disc to image the corona and measure its temperature and speed. Built by the Indian Institute of Astrophysics
Solar Ultraviolet Imaging Telescope (SUIT)	Images the photosphere and chromosphere in near ultraviolet. Built by the Inter-University Centre for Astronomy and Astrophysics, Pune
Solar Low Energy X-ray Spectrometer (SoLEXS)	Studies X-ray from the Sun in the soft band
High Energy L1 Orbiting X-ray Spectrometer (HEL1OS)	Studies hard X-rays from solar flares
Aditya Solar wind Particle Experiment (ASPEX)	Studies the solar wind and its energy
Plasma Analyser Package for Aditya (PAPA)	Studies the solar wind and composition of ions
Magnetometer	Measures the magnetic field in the L1 region

Why Go to L1 and What Are the Aims?

Lagrange point: a position where the pull of the Sun and the Earth balances the motion of a spacecraft, so little fuel is needed to stay there
Halo orbit: a loop around the L1 point, in a plane at an angle to the Sun-Earth line, which keeps the spacecraft out of the way of the Earth’s shadow
Constant view: no eclipse or occultation by the Earth or Moon
Coronal heating: why the corona is a million degrees hotter than the surface of the Sun is an open puzzle
Coronal mass ejections: large eruptions of plasma that can disturb Earth’s space weather and satellites
Solar wind: the stream of charged particles from the Sun, studied at L1 before it reaches Earth
Space weather: solar storms affect satellites, power grids and radio, so early warning is useful
Climate and Sun: long term observations help in separating solar and human influence on climate

What Else Should You Remember?

L1 versus other points: L1 lies between the Sun and Earth, L2 lies beyond Earth on the far side and hosts the James Webb Space Telescope, as in Space Observatories and Telescopes (Hubble, Chandra X-Ray Observatory, Thirty Metre Telescope, Spitzer Space Telescope)
Other solar missions: SOHO of NASA and ESA sits at L1, and the Parker Solar Probe has flown very close to the Sun. Solar Orbiter of ESA studies the poles of the Sun
Name: Aditya is the Sanskrit name for the Sun
Earlier plan: the mission was first planned as Aditya-1 to study only the corona from low Earth orbit and was expanded to an L1 observatory
Travel: after launch, the spacecraft raised its orbit around Earth and then went to L1 on a path that took about 127 days
Orbit insertion: a final engine burn on 6 January 2024 put it into a halo orbit, keeping it there takes small corrections
First results: the SUIT instrument took the first full disc ultraviolet images of the Sun in different wavelengths, and VELC and others have made observations of flares and mass ejections
Data sharing: data are released through the Indian Space Science Data Centre for scientists
Sunspots: dark cooler regions linked to magnetic fields and flares, as in Sunspots, Magnetars and Neutron Stars
Space weather in India: space weather alerts matter for navigation, communication and power systems, and ISRO runs a space weather programme
Aditya-L1 and Chandrayaan: success of PSLV and orbit manoeuvres helped to build confidence for deeper missions
Cooperation: scientists from several institutes in India took part in building payloads, a model of academic participation

Why Does It Matter for the Exam?

Facts: launch date, rocket, orbit and distance
Payloads: VELC as the main one
Concepts: Lagrange points and halo orbit
Current affairs link: solar maximum and space weather alerts
Common errors: saying that Aditya-L1 is on the Sun or that L1 is on the far side of Earth

As an analytical point, Aditya-L1 connects basic science with practical space weather forecasting. Data over a full solar cycle will help to protect satellites and strengthen India’s role in solar physics.

Why Is This Topic Important?

Facts Dates and orbit
Payloads VELC and SUIT
Use Space weather

What Came Next?

The next topic covers space missions of NASA, ESA, Roscosmos, JAXA and the Chinese space agency. Next topic: NASA, ESA, Roscosmos, JAXA and CNSA Space Missions.

Key People and Terms

Corona Outer atmosphere of the Sun
Coronagraph Instrument blocking the Sun’s disc
Halo orbit Loop around a Lagrange point
CME Coronal mass ejection
Solar wind Particle stream from the Sun
L1 First Lagrange point

Exam Corner

Points to Remember

Launched: 2 September 2023.
Reached L1: 6 January 2024.
Distance: about 1.5 million km.
Seven payloads, main one VELC.
Launch vehicle: PSLV-C57.

Do Not Confuse With

L1 and L2 Sunward point versus far side point
Aditya-L1 and Parker Solar Probe Observatory at L1 versus close approach probe
Corona and photosphere Outer atmosphere versus visible surface

Memory Hook

Aditya at L1, million and a half away, seven eyes on the Sun, five years to stay.

Mains Angle

Questions ask about facts, payloads and aims. These points help.

Aims Corona and solar wind
Value Space weather
Capability Deep space operations

A Question You May Face

An original practice question, not a past paper question.

“Discuss the objectives of Aditya-L1 and its importance for space weather forecasting and solar science.”

How to Answer

Facts L1, payloads.
Aims Corona, flares.
Use Space weather.
Way Data sharing.

GS Relevance

Prelims: launch date, L1, payloads, objectives. GS Paper 3: science and technology, space science.

Frequently Asked Questions

What is Aditya-L1?

Aditya-L1 is India's first space-based observatory dedicated to studying the Sun. It was launched on 2 September 2023 by PSLV-C57 and placed in a halo orbit around the first Lagrange point of the Sun-Earth system on 6 January 2024. It carries seven instruments to study the corona, flares and the solar wind.

What is the Lagrange point L1?

L1 is the first Lagrange point of the Sun-Earth system, lying about 1.5 million kilometres from Earth in the direction of the Sun. At this point the gravity of the Sun and Earth together keeps a spacecraft moving with the Earth, so it needs little fuel and has an uninterrupted view of the Sun.

Which is the main payload of Aditya-L1?

The Visible Emission Line Coronagraph, or VELC, is the main payload of Aditya-L1. It blocks the bright disc of the Sun, like an artificial eclipse, to image the faint corona and measure its temperature, speed and magnetic field. It was developed by the Indian Institute of Astrophysics in Bengaluru.

Why is the study of the Sun important?

The Sun drives space weather, in which solar flares and coronal mass ejections can disturb satellites, radio communication, navigation and power grids on Earth. Studying the corona, solar wind and magnetic field helps scientists to understand and forecast such events, and to learn why the corona is so hot.

How long did Aditya-L1 take to reach L1?

Aditya-L1 took about four months, or roughly 127 days, from launch on 2 September 2023 to insertion into its halo orbit around L1 on 6 January 2024. It first raised its orbit around the Earth in several burns and then travelled to the L1 point, about 1.5 million kilometres away.

PYQ Practice — Statement Analysis

1 Aditya-L1 was placed in a halo orbit around the first Lagrange point.

True

On 6 January 2024.

2 Aditya-L1 was launched by an LVM3 rocket.

False

It was launched by PSLV-C57.

3 The Visible Emission Line Coronagraph studies the corona.