Type: Prelims Only

Spacex’s newest fleet of satellites is tumbling out of orbit after being struck by a solar storm.

Solar Storm

• A solar storm or a Coronal Mass Ejection as astronomers call it is an ejection of highly magnetized particles from the sun.
• These particles can travel several million km per hour and can take about 13 hours to five days to reach Earth.
• Earth’s atmosphere protects us, humans, from these particles.
• But the particles can interact with our Earth’s magnetic field, induce strong electric currents on the surface and affect man-made structures.

How did they impact SpaceX satellites?

• The issue came up due to increased drag created by the solar storm in the upper reaches of the Earth’s atmosphere.
• These storms cause the atmosphere to warm and atmospheric density at our low deployment altitudes to increase.
• In fact onboard GPS suggests the escalation speed and severity of the storm caused atmospheric drag to increase up to 50 percent higher than during previous launches.

History of solar storms

• The first recorded solar storm occurred in 1859 and it reached Earth in about 17 hours.
• It affected the telegraph network and many operators experienced electric shocks.
• A solar storm that occurred in 1921 impacted New York telegraph and railroad systems and another small-scale storm collapsed the power grid in Quebec, Canada in 1989.
• A 2013 report noted that if a solar storm similar to the 1859 one hit the US today, about 20-40 million people could be without power for 1-2 years, and the total economic cost will be $0.6-2.6 trillion.

Why are they a cause of concern?

• The Sun goes through an 11-year cycle – cycles of high and low activity.
• It also has a longer 100-year cycle.
• During the last three decades, when the internet infrastructure was booming, it was a low period.
• And very soon, either in this cycle or the next cycle, we are going towards the peaks of the 100-year cycle.
• So it is highly likely that we might see one powerful solar storm during our lifetime.

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Scientists in the United Kingdom have achieved a new milestone in producing nuclear fusion energy or imitating the way energy is produced in the Sun. The record and scientific data from these crucial experiments are a major boost for ITER.

ITER Project

• ITER is international nuclear fusion research and engineering megaproject, which will be the world’s largest magnetic confinement plasma physics experiment.
• The goal of ITER is to demonstrate the scientific and technological feasibility of fusion energy for peaceful use.

Project details

• The project is funded and run by seven member entities—the European Union, India, Japan, China, Russia, South Korea and the United States.
• The EU, as host party for the ITER complex, is contributing about 45 per cent of the cost, with the other six parties contributing approximately 9 per cent each.
• Construction of the ITER Tokamak (doughnut-shaped apparatus) complex started in 2013 and the building costs were over US$14 billion by June 2015.

How does it work?

• Hydrogen plasma will be heated to 150 million degrees Celsius, ten times hotter than the core of the Sun, to enable the fusion reaction.
• The process happens in a doughnut-shaped reactor, called a tokamak, which is surrounded by giant magnets that confine and circulate the superheated, ionized plasma, away from the metal walls.
• The superconducting magnets must be cooled to -269°C (-398°F), as cold as interstellar space.
• Scientists have long sought to mimic the process of nuclear fusion that occurs inside the sun, arguing that it could provide an almost limitless source of cheap, safe and clean electricity.
• Unlike in existing fission reactors, which split plutonium or uranium atoms, there’s no risk of an uncontrolled chain reaction with fusion and it doesn’t produce long-lived radioactive waste.

Back2Basics: Nuclear Fusion

• Nuclear fusion is the process of making a single heavy nucleus (part of an atom) from two lighter nuclei. This process is called a nuclear reaction.
• The nucleus made by fusion is heavier than either of the starting nuclei. It releases a large amount of energy.
• Fusion is what powers the sun. Atoms of Tritium and Deuterium (isotopes of hydrogen, Hydrogen-3 and Hydrogen-2, respectively) unite under extreme pressure and temperature to produce a neutron and a helium isotope.
• Along with this, an enormous amount of energy is released, which is several times the amount produced by fission.
• Scientists continue to work on controlling nuclear fusion in an effort to make a fusion reactor to produce electricity.

How it is different from nuclear fission?

• Simply put, fission is the division of one atom into two (by neutron bombardment), and fusion is the combination of two lighter atoms into a larger one (at a very high temperature).
• Nuclear fission takes place when a large, somewhat unstable isotope (atoms with the same number of protons but a different number of neutrons) is bombarded by high-speed particles, usually neutrons.

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This newscard is an excerpt from the original article published in TH.

What are ANN?

• The concept behind an ANN is to define inputs and outputs, feed pieces of inputs to computer programs that function like neurons and make inferences or calculations.
• It then forwards those results to another layer of computer programs and so on, until a result is obtained.
• As part of this neural network, a difference between intended output and input is computed at each layer and this difference is used to tune the parameters to each program.
• This method is called back-propagation and is an essential component to the Neural Network.

Setting up of ANNs

• Instead of CPUs, Graphic Processing Units (GPU) which are good at performing massive parallel tasks can be used for setting up ANNs.
• A few free ANN frameworks are TensorFlow, Keras, PyTorch and Theano.
• These can be used for both normal Machine Learning tasks like classification or clustering and for Deep Learning/ANN tasks.

Why called Neural Network?

• Neuron is the building block of the brain and it inspired computer scientists from the 1950s to make a computer perform tasks like a brain does.
• It is not a simple problem and the clue to its complexity is in the brain structure.

Why ANN?

Ans. Making an artificial brain

• We need billions of artificial neurons if we were to build an artificial brain.
• With the increase in computing power, mimicking billions of neurons is now possible.

Popularity of ANNs

• Data Science, used interchangeably with Machine Learning, is the computer technology that uses data to detect patterns.
• Hand-written digit recognition is a good example of machine learning.
• However, in order for the computer to do this task, large amounts of sample data need to be manually labelled as examples of images of digits.
• The ANN mentioned above with its backpropagation does exactly this.
• This is why ANNs have become hugely popular in the past decade. This approach of using neural networks of many layers to automatically detect patterns and parameters is called Deep Learning.

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