UPSC Essentials | Daily subject-wise quiz : Science and Technology MCQs on re-entry of a spacecraft, microgravity and more (Week 119)

QUESTION 1

Which of the following critical materials are essential in electric motors, braking systems, smartphones and missile technology?

1. Samarium

2. Gadolinium

3. Terbium

4. Dysprosium

Select the correct answer using the codes given below:

(a) 1 and 2 only

(b) 2, 3 and 4

(c) 1 and 4 only

(d) 1, 2, 3 and 4

Explanation

— China’s prohibitions on the export of rare earth metals and related magnets are harming the domestic car and white goods industries.

— China controls more than 90% of the global processing capacity for magnets, which are utilised in a variety of industries such as vehicles, home appliances, and clean energy.

— Critical materials include samarium, gadolinium, terbium, dysprosium and lutetium, which are essential in electric motors, braking systems, smartphones and missile technology.

Therefore, option (d) is the correct answer.

QUESTION 2

With reference to microgravity, consider the following statements:

1. Astronauts experience space sickness in their initial days in microgravity.

2. Living in microgravity teaches the brain not to listen to the outer ear.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation

— Astronauts experience space sickness in their initial days in microgravity because the brain gets confused with the gravity and acceleration information it receives from the inner ear — the information that is essential for maintaining balance on Earth. Hence, statement 1 is correct.

— Living in microgravity teaches the brain to not listen to the inner ear, which becomes a challenge when they return to Earth as they face difficulty in standing up and walking. Hence, statement 2 is not correct.

— Shukla and his crewmates, who spent only 18 days on the ISS, are likely to experience far fewer severe symptoms. The severity of symptoms is greater in individuals on long-duration missions.

— Astronauts require reconditioning after returning to Earth in order to cope with the symptoms they experience. They are also more likely to get injuries after spending time in space. Astronauts have difficulty balancing and focussing their eyes, and they may feel difficulties while standing up. Their spine may be impacted, and they may have mobility issues.

Therefore, option (a) is the correct answer.

QUESTION 3

With reference to the re-entry of a spacecraft, consider the following statements:

1. When a spacecraft re-enters the Earth’s atmosphere, it experiences acceleration due to friction.

2. The spacecraft travels vertically to Earth at 90 degree angle.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation

— When a spacecraft re-enters the Earth’s atmosphere, it experiences deceleration due to friction. But additional measures are required to slow it to safe speeds. Hence, statement 1 is not correct.

— One such method is to employ parachutes. Spacecraft often deploy two drag (or drogue) parachutes first, which stabilise the vehicle during re-entry and lower speed. These parachutes are deployed by the Dragon spacecraft at an altitude of around 18,000.

— At approximately 6,500 feet, the drogue parachutes are removed, and the four main parachutes are released, further slowing the ship.

— The spaceship does not fly vertically to Earth, but rather descends at an angle. From re-entry to touchdown, it travels 5,000-7,000 kilometres. During this period, its speed drops to around 25-30 km/h, which is safe for a splashdown in the ocean. Hence, statement 2 is not correct.

Therefore, option (d) is the correct answer.

QUESTION 4

Which of the following countries has proposed to use copyright law to protect against deepfakes?

(a) Australia

(b) China

(c) Denmark

(d) Norway

Explanation

— Denmark has proposed extending copyright protections to persons’ face characteristics, appearance, and voice in an innovative effort to combat the rise of deepfake content, which is increasingly pervasive on the Internet.

— The proposed amendment to Denmark’s copyright law will effectively make it illegal to share deepfake content of another person without their consent, allowing individuals to have such forgeries removed from online platforms and seek compensation for their publication, similar to how copyright laws have traditionally protected creative works.

— Deepfakes are a form of synthetic media which depict believable and realistic videos, pictures, or audio of events that never happened — they show real people doing or saying things that they never did or said.

Therefore, option (c) is the correct answer.

QUESTION 5

With reference to the GLP-1, consider the following statements:

1. It is both an incretin hormone and a neurotransmitter.

2. It is secreted from the small intestine and from the hindbrain after we eat a meal.

3. It travels to the pancreas, where it helps to regulate our blood sugar by increasing insulin and decreasing glucagon.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Explanation

— GLP-1 is both an incretin hormone and a neurotransmitter. In physiology, it is secreted from the small intestine and from the hindbrain after we eat a meal. Hence, statements 1 and 2 are correct.

— It travels to the pancreas, where it helps to regulate our blood sugar by increasing insulin and decreasing glucagon. This is what we call the incretin effect. This effect is blood glucose-dependent, meaning it is only if the blood glucose is elevated that it has an effect here. Hence, statement 3 is correct.

— GLP-1 also impacts centres in the brain associated with control of hunger and satiety, to effectively tell us that we have had enough to eat and need to stop eating.

— There are receptors that GLP-1 binds to in many organs in the body, and GLP-1 also has beneficial effects in many of these organs, such as the kidney, liver, and cardiovascular system. GLP-1’s effects in the pancreas and brain are the important ones to help control blood glucose and body weight.

Therefore, option (c) is the correct answer.

QUESTION 6

What was the ‘Tunguska explosion’ of 1908?

(a) First nuclear test to be failed

(b) A fatal experiment involving toxic Polonium

(c) An asteroid impact event

(d) Collision between stars causing a supernova

Explanation

— The asteroid that likely wiped out the dinosaurs 66 million years ago was about 10 km wide. It struck with the energy of 10 billion Hiroshima bombs, creating a crater over 150 km across and changing Earth’s climate in a matter of hours. While such events are rare, smaller impacts—like the Tunguska explosion in Siberia (1908), which flattened over 2,000 square kilometers of forest—are far more frequent.

— According to NASA.gov, “On June 30, 1908, an asteroid plunged into Earth’s atmosphere and exploded in the skies over Siberia. Local eyewitnesses in the sparsely populated region reported seeing a fireball and hearing a large explosion. They also reported massive forest fires, and trees blown over for miles.”

Therefore, option (c) is the correct answer.

QUESTION 7

Consider the following statements:

I. Landing in the ocean is the preferred way to bring back astronauts from space.

II. The low viscosity and high density of water provides a much greater cushion not ensuring a completely smooth landing but it absorbs enough shock from the impact to avoid damage to the spacecraft’s structure, payload, or the crew inside.

Which one of the following is correct?

(a) Both I and II are correct, and II explains I

(b) Both I and II are correct, but II does not explain I

(c) I is correct, but II is incorrect

(d) I is incorrect, but II is correct

Explanation

— The spacecraft carrying Indian astronaut Shubhanshu Shukla and his three colleagues on the Axiom-4 mission splashed down in the Pacific Ocean on Tuesday after a 20-hour journey from the International Space Station.

— Landing in the ocean is the preferred way to bring back astronauts from space, though some spacecraft also make a landing on a runway like an aircraft. But the latter has special requirements, needs more sophisticated systems, and is usually costlier.

— It is safer to land a spacecraft in water even when it is travelling at 25-30 km per hour — the speed of the Axiom-4 spacecraft at the time of splashdown. The low viscosity and high density of water provides a much greater cushion. While it does not ensure a completely smooth landing, it absorbs enough shock from the impact to avoid damage to the spacecraft’s structure, payload, or the crew inside.

Therefore, option (a) is the correct answer.

QUESTION 8

What was the goal of NASA’s DART Mission?

(a)Demonstrated technologies required for LISA

(b)Demonstrated the use of galactic pulsars as navigational beacons

(c) Studied the health of Earth’s climate and ocean

(d) Demonstrated asteroid deflection with a kinetic impactor

Explanation

— If we discover an object on a collision course, our best defense is time. The more lead time we have, the smaller the nudge needed to shift an asteroid’s path away from Earth.

— In 2022, NASA tested one such idea with the DART mission (Double Asteroid Redirection Test). The spacecraft crashed into a small asteroid moonlet, changing its orbit—a real-world demonstration that we can, in principle, deflect asteroids.

— According to science.nasa.gov, “DART was the first-ever mission dedicated to investigating and demonstrating one method of asteroid deflection by changing an asteroid’s motion in space through kinetic impact.”

Therefore, option (d) is the correct answer.

Previous Daily Subject-Wise-Quiz

Daily Subject-wise quiz — History, Culture, and Social Issues (Week 117)

Daily subject-wise quiz — Polity and Governance (Week 119)

Daily subject-wise quiz —  Science and Technology (Week 118)

Daily subject-wise quiz — Economy (Week 118)

Daily subject-wise quiz — Environment and Geography (Week 118)

Daily subject-wise quiz – International Relations (Week 118)

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