Aditya-L1: How Will India's First Solar Mission Survive The Sun's Heat? Will It Not Burn Up?

Just hours away from now, India's first space-based solar observatory, Aditya-L1, is scheduled for launch at 11.50 am today. The spacecraft will be placed in a halo orbit around the Sun-Earth L1 Lagrange point, which is located about 1.5 million kilometers from Earth and 148.5 million kilometers from the Sun. This puts Aditya-L1 at a mere one percent of the Sun-Earth distance.

Will Aditya-L1 touch the Sun?

Aditya-L1 will remain at this specific distance from the Sun and will not venture any closer. It will orbit around Lagrange point 1 (L1), a unique location in space where the gravitational forces from both the Sun and Earth are counteracted by the centripetal force necessary to maintain an object's motion under the influence of gravity. This equilibrium at L1 will keep Aditya-L1 in a stable position, allowing it to orbit effortlessly in the halo orbit without expending significant fuel.

Moreover, Aditya-L1's placement at L1 will provide several advantages. It not only conserves energy by reducing the need for fuel but also offers an uninterrupted view of the Sun for a continuous period of five years.

Manish Purohit, a former ISRO scientist, highlighted the strategic significance of L1, as it enables Aditya-L1 to observe the Sun's behavior and gather vital data without direct exposure to the Sun's searing environment.

Which spacecraft has come closest to the Sun?

Regarding the spacecraft that has come closest to the Sun, NASA's Parker Solar Probe, launched in 2018, achieved this remarkable feat in 2021. It became the first spacecraft to "touch" the Sun by flying through its corona, the uppermost layer of the Sun's atmosphere, at a distance of 8.5 million kilometers from the solar surface.

Parker Solar Probe is expected to surpass its own record and achieve an even closer approach to the Sun by 2025, reaching a distance of 6.16 million kilometers from the Sun's surface. Debadatta Mishra, a former ISRO scientist, indicated that the probe is on track to achieve this feat, which will be a testament to the advancements in space technology and our comprehension of celestial mechanics.

Over a span of seven years, Parker Solar Probe is slated to complete 24 orbits around the Sun, coming more than seven times closer to the Sun than any other spacecraft. It employs gravitational assists from Venus to approach the Sun closely.

How Will India's First Solar Mission Survive The Sun's Heat?

Aditya L1 will not burn up in the Sun's heat because it will not actually be going into the Sun. It will be placed in a halo orbit around the Sun-Earth L1 Lagrange point, which is located about 1.5 million kilometers from Earth and 148.5 million kilometers from the Sun. This puts Aditya L1 at a mere one percent of the Sun-Earth distance.

The Sun's heat is still very intense at this distance, but Aditya L1 will be protected by a heat shield made of a special material called MLI (Multi-Layer Insulation). The MLI will reflect most of the Sun's heat away from the spacecraft, keeping it cool enough to operate. The MLI on Solar and Heliospheric Observatory (SoHO) consists of numerous layers of aluminized mylar, a thin and reflective material. To shield it from the harsh conditions of space, the MLI is coated with a protective layer.

In terms of cooling, SoHO employs a liquid helium-based system to maintain the spacecraft's instruments at a safe operating temperature. Liquid helium, known for its extreme coldness and high heat-absorbing capacity, is utilized to cool the spacecraft's instruments to approximately -270°C.

In addition to the heat shield, Aditya L1 will also have a number of other protective measures, such as radiation shielding and a sunshade. These measures will help to ensure that the spacecraft can survive the harsh environment of space and continue to operate for its planned five-year mission.