Aditya-L1 Is At Right Place, Will Help Entire World And Not Just India: ISRO Chief

New Delhi: India has achieved another major space milestone by precisely placing Aditya-L1, the country’s first space-based solar observatory to study the Sun, in the intended orbit. Aditya-L1’s home is a halo orbit around the Sun-Earth Lagrange Point 1 (L1), a special strategic and vantage point in space that will offer the spacecraft an uninterrupted view of the Sun for the entirety of its mission duration, which is five years, and will also allow the space vehicle to conserve energy by saving fuel. 

However, the Indian Space Research Organisation (ISRO) had to make some trajectory corrections to precisely place Aditya-L1 in the final destination, the space agency’s chief S Somanath has said. 

ISRO Chief on trajectory correction manoeuvres for Aditya-L1

According to Somanath, Aditya-L1 was moving towards a high orbit, but ISRO had to make some corrections to position the spacecraft in the right place, news agency ANI reported. He explained that the Aditya-L1 satellite’s velocity had to be maintained at 31 metres per second to ensure it had the correct orientation. 

Describing the halo orbit, Somanath said it is shaped like an egg, and had ISRO not conducted the corrections, Aditya-L1 would have escaped from its position. The chosen halo orbit around L1 is a three-dimensional figure, and measures over two lakh kilometres along the X-axis, over 6.5 lakh kilometres along the Y-axis, and 1.2 lakh kilometres along the Z-axis, according to ISRO. 

Somanath explained that ISRO will not allow Aditya-L1 to escape, but mathematically, the spacecraft can escape. 

#WATCH | On ISRO’s Solar Mission Aditya-L1 entering Halo Orbit, ISRO Chairman S Somanath says, “Today’s event was only placing the Aditya-L1 in the precise Halo orbit. So it was moving towards a high orbit, but we had to do a little bit of corrections… So right now, in our… pic.twitter.com/UgUpWDzIY4

— ANI (@ANI) January 6, 2024

He stated that ISRO achieved an exact placement of Aditya-L1 based on the space agency’s calculations, and correctly predicted the velocity requirements. However, ISRO will monitor the solar observatory for the next few hours if it is in the right place. 

“If ISRO didn’t perform today’s correction manoeuvres, we might have lost the spacecraft. But ISRO had contingency plans. Currently, ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru, is orbiting the spacecraft to obtain the orbit determination data,” Manish Purohit, a former ISRO scientist, who was involved in the Mangalyaan-1 and Mangalyaan-2 missions, told ABP Live. 

Constant monitoring by ground control stations is essential to ensure that the spacecraft does not escape from its final destination. 

This process is called station keeping, Purohit said. 

According to Somanath, ISRO may have to conduct further corrections if Aditya-L1 drifts from its home. However, this is unlikely to happen.

Aditya-L1 will help the entire world, and not just India: ISRO Chief

Somanath explained that Aditya-L1 will help not just India, but the entire world by making observations, obtaining data, and conducting experiments that will provide significant information on space weather, which is controlled by the Sun’s behaviour. 

Emissions from the Sun also control external magnetic fields, and affect the northern latitudes more than the southern latitudes.

The ISRO Chief said that solar activities do not have much impact in the equatorial regions, and that the effects are more prominent in regions other than India. 

ISRO Chief on Aditya-L1’s scientific goals

Explaining the scientific objectives of Aditya-L1, the ISRO Chief said the Visible Emission Line Coronagraph, the spacecraft’s primary payload designed by the Indian Institute of Astrophysics (IIA), will observe solar coronal mass ejections. 

Large expulsions of plasma and magnetic fields from the Sun’s corona are called coronal mass ejections. 

The Solar Ultraviolet Imaging Telescope (SUIT), an ultraviolet telescope, will image the entire solar disc in the near-ultraviolet wavelength range. It will conduct imaging of the photosphere and the chromosphere. The photosphere is the innermost layer of the solar atmosphere, and the chromosphere is the layer between the corona and the photosphere. 

The ISRO Chief explained that the SUIT payload will observe the Sun’s disc in ultraviolet in various frequency bands.

The Plasma Analyser Package for Aditya (PAPA) is a particle analyser that will conduct particle measurements, observing what comes out of the Sun. It will understand solar winds and its composition, analyse solar wind ions, and study electrons and heavier ions in solar winds in different directions. 

The Solar Low-Energy X-ray Spectrometer (SoLEXS), and the High-Energy L1 Orbiting X-ray Spectrometer (HEL1OS) are remote sensing payloads that will conduct X-ray measurements. 

SoLEXS is a soft X-ray spectrometer that will study solar flares by measuring the solar soft X-ray flux, or the number of low-energy X-ray lines coming out of the surface of the Sun in a given amount of time. 

These X-rays have longer wavelengths, and lower energies. 

HEL1OS, a hard X-ray spectrometer, will study solar flares by measuring high-energy X-rays, which have shorter wavelengths. 

On November 7, 2023, HEL1OS captured its first high-energy X-ray glimpse of solar flares. 

Data obtained from HEL1OS will enable researchers to study explosive energy release and electron acceleration during impulsive phases of solar flares, which is the phase during which electrons and other particles are accelerated after the stored energy in the magnetic field is released. 

The magnetometer will study magnetic fields in the space created due to coronal mass ejections. The payload, which has two sets of magnetic sensors — one of them at the tip of a six-metre deployable boom, and the other set in the middle of the boom, three metres away from the spacecraft — will measure the low-intensity interplanetary magnetic fields in space. 

It will also study the magnetic fields at the Lagrange Point 1 to understand how solar activities affect the magnetic fields in the interplanetary medium. 

“We look at all of this in a correlated manner. This is a unique part of the Aditya-L1 mission,” Somanath said.