VELC on board Aditya-L1 reveals asymmetric expansion of solar eruption that could impact space weather

1. At a Glance

• Scientists at the Indian Institute of Astrophysics (IIA) used VELC, the main payload on Aditya-L1, to show that a coronal mass ejection (CME) expanded asymmetrically. It did not grow like the simple symmetric bubble assumed earlier. [1]
• The shape of a CME affects how it interacts with the solar wind, the drag it meets in the heliosphere, and so its speed and arrival time at Earth. This makes the shape central to space-weather forecasting. [1]
• The method is new: VELC measures motion along the line of sight using Doppler spectroscopy of the 530.3 nm Fe green line. NASA's SDO/AIA images show motion across the sky (plane-of-sky motion). Together they give a full 3-D picture. [1]
• It matters for UPSC as GS-III (Space technology, Indigenisation, Disaster management/critical infrastructure) and as a recurring Prelims theme (Aditya-L1 payloads, the L1 point, space weather).

2. Why in the News

• PIB release dated 03 Nov 2026: VELC results show an inclined CME axis with asymmetric sideways (lateral) expansion in the CME of 5 August 2024. [1]
• Context: earlier Aditya-L1 science outputs from the storms of 2024, including a joint study with ESA's Proba-3 and multi-spacecraft studies of CMEs. [5][6][7]

3. Background & Evolution

• 2 Sep 2023: Aditya-L1 launched on PSLV-C57. It is India's first space-based solar observatory. [1][3]
• 6 Jan 2024: placed in a halo orbit around Sun–Earth L1. [3]
• VELC was designed and built by IIA at the MGK Menon Lab for Space Sciences, CREST campus, Hosakote, with substantial ISRO support. IIA then handed the payload over to ISRO. [1][9]
• 8–11 May 2024: storm from active region AR13664. SoLEXS and HEL1OS recorded the flares on 8–9 May. ASPEX and MAG recorded the storm passing L1 on 10–11 May. [3]
• VELC and SUIT missed the peak because they were in calibration and baking modes. Their doors opened on 14 May 2024, and VELC then scanned the corona in the 5303 Å line. [3]
• 5 Aug 2024: the CME used in the present VELC study erupted. [1]
• Jan 2026: ISRO's first Announcement of Opportunity (AO) cycle for Aditya-L1 opened observing time on VELC and SUIT to outside researchers. [8]

4. Core Static Facts

Key terms

• Doppler shift: a shift towards blue means plasma moving towards the observer; a shift towards red means plasma moving away. [1]
• 3-D geometric–kinematic model: the symmetric-expansion model failed to reproduce the observed spectra. An inclined axis with asymmetric sideways expansion matched the spectra and how they changed over time. [1]

5. Multi-Dimensional Analysis

Scientific / Technological

• This is the first evidence of asymmetric CME expansion using spectroscopy in the lower corona. That region is hard to study because CMEs change fast there and imaging alone cannot measure line-of-sight motion. [1]
• It shows that imaging and spectroscopy work best together. It also shows the value of a coronagraph that observes in several modes at once. [1]
• The finding should improve CME drag and arrival-time models, which affects forecast accuracy. [1]

Economic / Critical Infrastructure

• CMEs can disrupt satellites and communication networks. [1]
• Satellites in geosynchronous orbit are especially exposed to charging and to damage from energetic particles. [10]
• In Feb 2022, storm heating of the upper atmosphere raised drag enough to bring down about 38 commercial satellites. [11]
• A CME usually takes 3–5 days to reach Earth, so early detection near the Sun gives usable warning time. [10]

Strategic / Self-reliance

• Aditya-L1 gives India its own continuous solar monitoring from L1, which reduces reliance on foreign assets such as SOHO and SDO. [2]
• The space-based coronagraph was built indigenously by IIA (DST) together with ISRO, a model of collaboration between research institutes and the space agency. [1][9]

Disaster Management / Governance

• 10 May 2024 brought the strongest geomagnetic storm in about two decades. Intense storms on 10 May and 10 Oct 2024 were studied using Aditya-L1 data. This shows space weather is a real hazard, not a theoretical one. [4][7]
• The AO cycle (2026) opens data to the wider research community, which helps the open-science ecosystem. [8]

International Cooperation

• VELC has made joint observations with ESA's Proba-3 coronagraph. [5]
• Aditya-L1 has also been part of global multi-spacecraft studies of solar storms. [6]
• The present study used NASA's SDO data. [1]

6. Recent Developments (last 12–18 months)

• Jan 2026: ISRO launched the first Aditya-L1 AO cycle for VELC and SUIT observing time. [8]
• 2025–26: ISRO reported several science results: the joint VELC–Proba-3 view of eruptions near their source, Aditya-L1 joining a landmark global storm study, and ASPEX data explaining unusual dawn-time geomagnetic disturbances. [5][6][7]
• 03 Nov 2026: PIB announced the VELC asymmetric-CME result. [1]

7. Prelims Hooks

• VELC stands for Visible Emission Line Coronagraph. It is Aditya-L1's primary payload. [1]
• VELC was designed and built by IIA, Bengaluru, an autonomous body under DST. [1]
• VELC was built at the MGK Menon Lab, CREST campus, Hosakote. [1]
• Aditya-L1 carries 7 payloads. [1]
• Aditya-L1 was launched on 2 Sep 2023 on PSLV-C57. [3]
• It entered a halo orbit around L1 on 6 Jan 2024. [3]
• VELC observes the 530.3 nm green line of highly ionised iron, which traces plasma at about 1.8 million K. [1]
• A shift towards blue means plasma is moving towards the observer; a shift towards red means it is moving away. [1]
• The CME in the study erupted on 5 August 2024. [1]
• The imaging partner was NASA's SDO, Atmospheric Imaging Assembly (AIA). [1]
• The L1 halo orbit gives a view of the Sun with no occultation or eclipses. [2]
• During the May 2024 storm, the source active region was AR13664. [3]
• The 10 May 2024 geomagnetic storm was the strongest in about two decades. [4]
• VELC and SUIT data are handled by Payload Operation Centres at IIA Bengaluru and IUCAA Pune. [8]

8. What One CME Can and Cannot Prove

• The result comes from one eruption, seen through a narrow window
• The study follows a single CME, the one of 5 August 2024 [1].
• It covers only the lower corona (the Sun's outer atmosphere close to its surface), from 1.05 to 1.5 solar radii [1].

• So it shows that asymmetric expansion can happen. It does not yet show how often it happens, or whether the shape stays the same as the CME travels about 150 million km to Earth.

• The "symmetric bubble" was a simplifying guess, not a proven law

• The symmetric model failed to match VELC's spectra. A tilted axis with lopsided sideways growth did match [1].

• This is an argument for testing many CMEs. Forecasters cannot change their models because of one case.

• VELC only helps when there is a clear eruption to watch

• Another IIA study traced an intense geomagnetic storm to a faint "stealth" eruption that was hard to spot at the Sun [12].
• A storm like that can reach Earth without giving VELC a clear eruption to measure, so better shape data does not remove the risk of surprise.

9. Why Knowing the Shape Is Not Yet a Better Forecast

• Arrival-time forecasts still miss by many hours
• NASA's CCMC CME Scoreboard compares forecasts with the times CMEs actually arrived. Recent entries for NOAA's official model (WSA-ENLIL+Cone) differ from actual arrival by about 10 to 25 hours [13].

• A grid operator or satellite team getting a warning that is a day off may act at the wrong time, or not act at all.

• Today's working model assumes the very shape VELC has now questioned

• The "Cone" in WSA-ENLIL+Cone means the CME is fed into the model as a simple, even cone [13].
• VELC's tilted, lopsided CME is exactly what a cone cannot capture. That is why the result matters [1].

• But the gain shows up only after someone actually changes the model inputs. Publishing the finding does not do that.

• Arrival time is only half the forecast. Strength is the other half

• IIA's study of three decades of solar storms found that a CME's thermal state (how hot its plasma is) affects how strongly it disturbs Earth's magnetic field [14].

• So a perfect arrival time still does not tell you whether the storm will be mild or severe.

• The last sure warning is very short

• Shock arrival is confirmed only when a spacecraft at L1 measures the solar wind directly. That gives just 15 to 60 minutes of warning before it hits Earth [15].
• Coronagraphs like VELC see the CME days earlier, in the 3–5 days it takes to travel [10]. That longer warning is useful only if the forecast is accurate.

10. A Science Mission, Not Yet a Warning Service

• Aditya-L1 was built to do research, not to send daily alerts
• Its data goes to Payload Operation Centres at IIA and IUCAA. Outside researchers get observing time through an AO (Announcement of Opportunity, a call for research proposals) cycle [8].

• That suits scientific papers. It is not the same as an agency that issues storm warnings round the clock.

• India's grid weather warnings do not cover space weather

• The IMD–POSOCO arrangement for the power grid covers events like thunderstorms and short-range nowcasts (warnings for the next few hours) [16].

• Geomagnetic storms can push unwanted electric currents into power lines and transformers. No equivalent alert is part of that system [16].

• One spacecraft means one point of failure

• In the US, NOAA's long-serving L1 satellite DSCOVR stopped sending data. SWPC had to switch to its new satellite, SOLAR-1, as the main source [17].
• The US could switch only because a replacement was already in orbit. India has only one L1 observatory, Aditya-L1, so it has no such backup.

11. What the US Built Around Its Solar Satellites

• A written national plan with named actions
• The US issued a National Space Weather Strategy and Action Plan in 2015 and updated it in 2019 [18].

• In December 2023 it added an Implementation Plan for the next five years, with 93 actions under 3 objectives [19][20].

• A law and a body that coordinates agencies

• The PROSWIFT Act of 2020 wrote the interagency group into law. Its SWORM subcommittee (Space Weather Operations, Research, and Mitigation) coordinates the federal agencies [20].

• A satellite built for warnings, not just research

• NOAA's SOLAR-1 (earlier called SWFO-L1) carries the CCOR-2 coronagraph. It was declared operational in June 2026 and feeds official forecasts [21].
• This is the difference for India: the US paired its science satellites with an operational warning system. India so far has only the science part.

12. Who Should Do What Next

• IIA should test the finding on many CMEs, not one

• The AO cycle already gives outside teams VELC observing time [8]. A planned campaign across many eruptions would show whether lopsided growth is common or rare.

• IIA and ISRO should feed VELC shapes into forecast models and publish the results

• The CCMC Scoreboard publicly compares each model's forecast with the actual arrival [13].

• Entering forecasts that use VELC's measured shape would show, in hours saved, whether the finding really improves forecasts.

• MoES/IMD and Grid-India (formerly POSOCO) should add geomagnetic storm alerts to the existing grid weather portal

• The IMD–POSOCO channel to grid operators already exists for terrestrial weather [16]. Space-weather alerts could use the same route.

• The Government should write a national space-weather plan with clear agency roles

• The US strategy, implementation plan and SWORM body show how to split work among research, operations and disaster agencies [18][20].

• ISRO should plan a follow-on L1 mission early

• The DSCOVR-to-SOLAR-1 handover shows why a replacement must be ready before the old satellite fails [17].

13. Anchors for Answers

• Data: Recent NOAA official CME arrival forecasts differ from actual arrival by about 10–25 hours (NASA CCMC Scoreboard) [13]
• Data: L1 spacecraft give only 15–60 minutes' sure warning of a shock reaching Earth [15]
• Data: US Space Weather Implementation Plan (Dec 2023) lists 93 actions under 3 objectives [19][20]
• Report/Committee: US National Space Weather Strategy and Action Plan (2015, updated 2019); SWORM subcommittee [18][20]
• Law/Case: US PROSWIFT Act, 2020, which wrote space-weather coordination into law [20]
• Comparison: US NOAA SOLAR-1 with the CCOR-2 coronagraph, operational June 2026, is a satellite built for daily warnings; Aditya-L1 is a research observatory [21]
• Scheme: Aditya-L1 AO cycle (Jan 2026) opens VELC/SUIT observing time, which could support a study across many CMEs [8]

14. Mains Relevance

• GS-III: Science & Technology, covering achievements of Indians in S&T, indigenisation of technology, and awareness in the field of space.
• GS-III: Disaster Management, covering space weather as a non-traditional hazard to critical infrastructure.
• GS-II (secondary): international cooperation in science (Proba-3, NASA SDO).

Question stems

1. "Aditya-L1 marks India's entry into space-based solar observation. Discuss its scientific objectives and its significance for protecting space-based and terrestrial infrastructure from space weather." (15 marks)
2. "Explain how combining spectroscopic and imaging observations improves forecasts of coronal mass ejections reaching Earth. Illustrate with recent findings from Aditya-L1's VELC." (10 marks)
3. "Space weather is an under-recognised disaster risk for a digitally dependent economy. Evaluate India's preparedness." (15 marks)

15. Related Topics to Study Next

• Lagrange points (L1–L5): why L1 suits continuous solar viewing and how a halo orbit works.
• Other Aditya-L1 payloads (SUIT, SoLEXS, HEL1OS, ASPEX, PAPA, MAG): frequently asked Prelims "match the payload" questions.
• Solar flares vs CMEs vs solar wind: basic heliophysics distinctions.
• Geomagnetic storms and aurorae (the May 2024 Gannon storm): the impact pathway from Sun to Earth.
• ESA Proba-3 (precision formation flying): a joint coronagraph partner with India, launched on PSLV.
• NASA's SOHO, SDO and Parker Solar Probe: comparable international solar missions.
• Satellite drag and space debris / space situational awareness (ISRO's IS4OM): what space weather means for orbital assets.

16. NCERT Concepts to Revise

• Lagrange points (Geography): Aditya-L1 sits in a halo orbit at Sun–Earth L1, giving it a continuous, eclipse-free view of the Sun.
• Geomagnetic storm (Geography): CMEs that reach Earth trigger these storms, which harm satellites and power grids; the May 2024 storm is an example.
• Solar wind (Geography): A CME's shape changes how it interacts with the solar wind and the drag it meets, which affects arrival time.
• Weather forecasting (Geography): The note compares space-weather forecasting, including arrival-time errors and warning lead times, with ordinary forecasting methods and agencies.
• Self-reliance (Economy): Indigenous VELC and Aditya-L1 reduce India's dependence on foreign solar observatories such as SOHO and SDO.

17. Common Errors / Trap Areas

• Who built VELC: IIA, under DST, not ISRO's URSC or SAC. ISRO provided support and integration. [1][9]
• What CME stands for: the standard expansion is Coronal Mass Ejection. The PIB digest uses "eruption". Either is acceptable descriptively, but MCQs use "Ejection".
• Imaging vs spectroscopy: SDO/AIA images show motion across the sky (plane-of-sky motion). VELC's Doppler data show line-of-sight motion. Do not swap them. [1]
• Which shift means what: blue means approaching and red means receding. Aspirants often reverse these. [1]
• Dates: launch was 2 Sep 2023 and L1 insertion was 6 Jan 2024. The CME studied was 5 Aug 2024, not the May 2024 storm. VELC was not observing during 10–11 May 2024. [1][3]