Source: First Advance Estimates of India’s GDP out: What are they, and what do the data show? (The Indian Express, January 6)
India’s economic growth is propelled by four main factors. Understanding these components helps us grasp how the country’s Gross Domestic Product (GDP), a measure of economic activity, is powered.
- Consumer Spending: Consumer spending, or Private Final Consumption Expenditure (PFCE), is the dominant force behind India’s GDP. It represents the purchases made by individuals for their personal use, making up nearly 60% of the total GDP.
- Investment: Next, we have investment in assets that boost the economy’s productivity. Whether it is constructing a new factory, purchasing computers for a business, or the government developing infrastructure like roads, all this falls under Gross Fixed Capital Formation (GFCF). This investment activity contributes to about 30% of the GDP.
- Government Expenditure: The Government Final Consumption Expenditure (GFCE) reflects how much the government spends on its daily operations, including paying salaries. Although it’s the smallest engine, it still accounts for around 10% of the GDP.
- International Trade: Lastly, Net Exports represent the balance of trade, that is, the difference between what India earns from its exports and spends on imports. Since India usually imports more than it exports, this difference negatively impacts the GDP, indicated by a minus sign in the calculation.
Why ISRO’s Aditya spacecraft is at ‘L1’
Source: Experts Explain: Why ISRO’s Aditya spacecraft is at ‘L1’, what it means (The Indian Express, January 6)
ISRO launched Aditya-L1 on September 2, 2023, with the primary objective of observing and deepening our understanding of the Sun. This remarkable spacecraft reaches its destination, known as L1 or the first Sun-Earth Lagrangian point, on January 6.
Why study the Sun?
- Energy Production: The Sun’s energy comes from its core through a process called nuclear fusion. This energy travels outward to the Sun’s surface and beyond.
- The Sun’s Layers: Visible and infrared light that we see comes from a layer called the photosphere, which has a temperature of about 6,000 degrees Celsius. Above that is the chromosphere. The outermost layer is the corona, which is surprisingly hotter than the inner layers, reaching a temperature of a million degrees Celsius.
- The Solar Mystery: The reason the corona is hotter than the layers below it is not fully understood. Despite this, we know it releases dangerous ultraviolet and X-ray radiation.
- Earth’s Protection: Earth is saved from this harmful radiation by our atmosphere, which absorbs most of it before it can reach us.
- The Solar Wind: The Sun sends out a flow of charged particles, called the Solar wind. This wind creates the Northern and Southern Lights near Earth’s poles.
- Solar Events: Sometimes the Sun releases huge amounts of these particles suddenly. These events, called Solar flares and coronal mass ejections, impact our space technology and can even cause power outages on Earth. Predicting these events is a major challenge.
Mission Overview: Aditya-L1
- Location and Purpose: Aditya-L1 will float in space far from Earth. It will be 1.5 million km closer to the Sun than our planet. This position is key for studying the Sun’s outer layer, called the corona.
- Studying the Sun’s Atmosphere: The spacecraft can watch ultraviolet light from the corona. This helps us understand how it behaves. Such studies are vital and can only be done from space, well away from Earth.
- Monitoring Solar Activity: Continuous monitoring of the Solar atmosphere is crucial. This allows us to detect eruptions on the Sun. By studying these eruptions and solar winds, we can prepare for any potential disruptions on Earth.
- Scientific Instruments: The spacecraft carries seven tools. These instruments will collect all sorts of data, from radiation to charged particles. The location of Aditya-L1 ensures it can keep an eye on the Sun without any interruptions.
Understanding L1: Aditya’s Orbit Point
- The Basics of L1: L1 refers to the first of five Lagrangian points, named L1 through L5. These points relate to the positions in space where a small object, like a spacecraft, can be influenced by the gravitational pull of two larger objects, such as Earth and the Sun. Swiss mathematician Leonhard Euler and Italian-French mathematician Joseph-Louis Lagrange found these points in the 1800s. Space missions often use L1 and L2 points.
- Spacecraft Stability: In orbit, Earth’s gravity pulls on a spacecraft but doesn’t cause it to fall due to a counteracting centrifugal force. This force comes from the spacecraft’s orbit. As a spacecraft moves away from Earth, the planet’s pull gets weaker.
- The Sweet Spot: The L1 point is a specific spot in space. It lies between Earth and the Sun where the forces balance perfectly. The Sun’s and Earth’s gravities and the centrifugal force all cancel out here. If Aditya, a spacecraft, is placed at L1, it would stay put without using extra energy. This makes L1 an ideal location for observing the Sun.
The Significance of the L1 Position for Aditya
- Simpler Orbits vs. Uninterrupted Solar Observation: Using a simpler orbit around Earth for Aditya would lead to problems. Earth would block its view of the Sun often. Even with the best orbit choice, we can’t stop this completely. Aditya’s job is to constantly watch the Sun to alert us about solar activity.
- Continuous Solar Monitoring at L1: At L1, Earth is to one side and the Sun to the other. Aditya can then always look at the Sun without Earth getting in the way. Even though it’s hard to get a spacecraft to orbit around L1, the clear, constant view of the Sun makes it valuable.
- Other Missions at L1: Not just Aditya, but also other space missions value L1. NASA and the European Space Agency have their own missions there, like LISA Pathfinder and SOHO, which shows L1’s importance for solar observation.
Observing the Distant Universe from L2
- Location of L2: L2 is positioned directly opposite to the Sun from the Earth’s viewpoint. It is about 1.5 million kilometers away from Earth.
- Benefits for Spacecraft: A spacecraft orbiting L2 can keep its instruments aimed at deep space constantly. This means that the spacecraft gets a clear and steady view of the cosmos without Earth’s interference.
- Notable Missions at L2: The James Webb Space Telescope (JWST), along with Gaia and Euclid, orbits L2 and explores outer space. The Planck mission, known for its study of cosmic microwave background radiation, was also located at L2.