India launches Aditya-L1 solar observatory, its 1st-ever sun probe

Fresh off its success at the moon, India is now headed for the sun.

The nation launched its first-ever solar observatory today (Sept. 2), sending the Aditya-L1 probe skyward atop a Polar Satellite Launch Vehicle (PSLV) from Satish Dhawan Space Centre at 2:20 a.m. EDT (0620 GMT; 11:50 a.m. local India time).

The PSLV deployed Aditya-L1 into low Earth orbit (LEO) as planned about 63 minutes after liftoff, sparking applause and high fives in mission control.

"Congratulations, India, and congratulations, ISRO [the Indian Space Research Organisation]," Jitendra Singh, India's Minister of State for Science and Technology, said shortly after deployment on ISRO's launch webcast.

"While the whole world watched this with bated breath, it is indeed a sunshine moment for India," Singh added. 

The successful launch followed on the heels of another big milestone for India: On Aug. 23, its Chandrayaan-3 mission became the first to land softly near the moon's south pole

Chandrayaan-3's lander-rover duo are expected to conk out in a week or so, when the harsh lunar night falls at their touchdown site. But Aditya-L1's long journey has just begun.

Related: Facts about the sun's age, size and history

India's Aditya-L1 solar observatory rises into the sky on Sept. 2, 2023 atop a PSLV rocket. (Image credit: ISRO)

A long road to a good sun-viewing spot

Aditya-L1 won't stay in LEO forever: After a series of checkouts, it will use its onboard propulsion system to head toward Earth-sun Lagrange Point 1 (L1), a gravitationally stable spot about 1 million miles (1.5 million kilometers) from our planet in the direction of the sun.

That destination explains the latter part of the mission's name. And the first part is simple enough: "Aditya" translates to "sun" in Sanskrit.

The 3,260-pound (1,480 kilograms) observatory will arrive at L1 about four months from now, if all goes according to plan. But the long trek will be worth it, according to the ISRO.

"A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the sun without any occultation/eclipses," ISRO officials wrote in an Aditya-L1 mission description. "This will provide a greater advantage of observing the solar activities and its effect on space weather in real time."

Indeed, another sun-studying spacecraft is already at L1 — the Solar and Heliospheric Observatory (SOHO), a joint NASA-European Space Agency mission that launched in December 1995. (Several other spacecraft, including NASA's James Webb Space Telescope, are at Earth-sun Lagrange Point 2, which is a million miles from Earth, in the direction away from the sun.)

Solar flares, the coronal heating mystery and more

Once it's settled in at L1, the solar probe will use four three science instruments to study the particles and magnetic fields in its immediate surroundings and four others to scrutinize the sun's surface (known as the photosphere) and its atmosphere.

This work will help scientists better understand solar activity, including the dynamics of solar flares and coronal mass ejections (CMEs), ISRO officials say. Flares are powerful flashes of high-energy radiation, and CMEs are huge eruptions of solar plasma. 

Both types of outburst can affect us here on Earth. Intense CMEs that hit our planet, for example, trigger geomagnetic storms that can disrupt satellite navigation and power grids. (As a side benefit, such storms also supercharge the gorgeous light shows known as auroras.)

Aditya-L1 will also tackle the "coronal heating problem," one of the biggest mysteries in heliophysics. The corona — the sun's wispy outer atmosphere — is incredibly hot, reaching temperatures around 2 million degrees Fahrenheit (1.1 million degrees Celsius), according to NASA

That's about 200 times hotter than the solar surface, which is "only" 10,000 degrees F (5,500 degrees C) or so. It's still unclear what is responsible for this startling and counterintuitive discrepancy. (Why would it be hotter away from the sun's core, where the energy-producing nuclear fusion reactions are occurring?)

Aditya-L1 has other science goals as well. For instance, the mission also aims to more fully flesh out the solar wind, the stream of charged particles flowing constantly from the sun, ISRO officials said. Aditya-L1 will measure the composition of the solar wind and attempt to determine how it is accelerated.

And Aditya-L1 will do all this work on the cheap: The mission's price tag is about 3.8 billion rupees, or $46 million US at current exchange rates. That's in the same ballpark as Chandrayaan-3; India's first successful moon-landing mission costs about 6.15 billion rupees, or $74 million US.

For comparison, NASA's most recent big-ticket sun mission, the record-setting Parker Solar Probe, costs roughly $1.5 billion. This disparity should not be viewed as an indictment of NASA, however; labor costs are much higher in the United States than in India, among other differences between the two nations' economies.

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Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

  • DrRaviSharma
    Aditya L1 Mission
    Congratulations to ISRO, and investigators and researchers at URSC, IISC, IIA, IUCAA, others.
    We are looking for greater details than earlier missions on study of the Sun.
    Coronal Heating is to be understood in terms of the nuclear reactions, electromagnetic forces (plasma and other components of solar wind), and Gravitational attraction.
    In Non-equilibrium state of matter macro concepts such as temperature are to be better described in terms of relativistic quantum energy field properties.

    Recalling many old astronomy books in Indian Sanskrit literature and books in the US, I would like to briefly recall how my life has had connection with the Sun?
    - My own name as gift of Sun
    - Participated in studies with NRL on Rockets that looked at UV Spectroscopy of Sun in the 1960's Washington DC while working on Apollo Program.
    -Coronagraph images taken from CSM Apollo Missions
    -Designed and studied transmission characteristics of Astronauts Helmets for Moon's surface, with Late Dr Bob Hilberg (also colleague at Yale).
    - Study of Corona data from Apollo Telescope Mount on Skylab.
    - Smithsonian Astrophysical Observatory solar studies as well as IR studies from Frank Low's Lab at Arizona.
    - Met Prof S. Chandrasekhar Nobel Laureate, one in whose name NASA Launched Xray Observatory, one of the most knowledgeable Stellar Astrophysicist, also Prof Bethe, during Yale, who knew about solar interior as well as Prof W W Fowler - Nobel, Nucleosynthesis.
    - Astrophysicist Dr D S Kothari was mentor White Dwarf stars.
    -Bhaskara satellite of India was in a large part conceived and built as the first Remote sensing Satellite of India, for which I formed a team initially with Drs. Kasturirangan (Later Chair ISRO), George Joseph (Later Director SAC) and PS Goel (Later Director ISAC now called URSC).
    - Discussed Aditya L1 Mission in somewhat detail with my former colleague Late Prof U R Rao, Former Chair ISRO at ISRO HQ in March 2017 (Photo included).
    (Dr. Ravi Sharma, Ph.D. USA)
    NASA Apollo Achievement Award
    ISRO Distinguished Service Awards
    Former Scientific Secretary ISRO HQ
    Ontolog Board of Trustees
    Particle and Space Physics
    Senior Enterprise Architect
    Activate to view larger image, to view larger image,
  • DrRaviSharma
    Thinking further
    What factors would play if we were to attempt a model of solar corona nowadays. Please add your thoughts for important omitted factors not listed below:
    1. Gravitation modeling in warped Gen Relativity formalism at edge of sun's outer surface using what S Chandrasekhar described as Radiative Transfers in stellar atmospheres and interiors initially and in later years again explained it using Kerr Matrices (21 terms described) in Einstein Commemoration Volume brought out by Dr D S Kothari his colleague at Cavendish Lab and published earlier than 1980's as Chair of Indian National Science Academy (INSA) or further numerical models favored by modern relativistic astrophysicists.
    Model assumed to be based on Magnetohydrodynamics and CFD tools more advanced that only turbulent CFD Models.
    2. Solar shell models describing not only nucleosynthesis but also acoustic cum atomic plasma and photon creation and annihilation or re-emissions so as to result in 5500 deg K solar disc. This model yo include solar cosmic ray ejecta and nuclear elemental abundance observed in solar cosmic rays.
    3. Quantum relativistic and perhaps numeric only models that are suitable for problems such as fusion and plasma containment.
    Note: I do not know enough whether Quantum entanglement, Rabi, Rydberg or other Quantum states and effects would be significant.
    4. Energy transfer and transportation phenomena astrophysicists model when they learn about difficult boundaries such as Grey and Black Holes and dense gravitational environments.
    5. Filter out exotic environments such as Boson and Neutron stars and even off main sequence stars studies.
    6. Specifically in context of Aditya L1, the in situ and observed Corona data will help refine above model and further observed Earth Ionosphere data if matched will also improve our understanding of the Sun and perhaps flares and some idea of how sunspots are formed.
    Coordinate similarly with other space and ground solar observatories data , and integration approaches.
    Please add more factors or suggest removing some.
    Regards and Thanks.
    (Dr. Ravi Sharma, Ph.D. USA)
    NASA Apollo Achievement Award
    ISRO Distinguished Service Awards
    Former Scientific Secretary ISRO HQ
    Ontolog Board of Trustees
    Particle and Space Physics
    Senior Enterprise Architect