Subject: Space Technology

Central Idea

• Boundaries serve a crucial purpose in scientific understanding by providing clarity and distinction to elements that might otherwise merge.
• One such significant boundary is the Karman Line, which plays a pivotal role in delineating Earth’s atmosphere from outer space.

What is Karman Line?

• The Karman Line is an abstract boundary positioned at an altitude of 100 kilometers above sea level.
• Its primary function is to establish the separation between Earth’s atmosphere and the vast expanse of space.
• Although not universally accepted by all scientists and space explorers, the majority of countries and space organizations acknowledge this demarcation.
• It was formally established in 1960s by the Federation Aeronautique Internationale (FAI), a body responsible for record-keeping.
• Crossing the Karman Line designates an individual as an astronaut.

Challenges to the Karman Line’s Significance

• Nature rarely conforms to human-made boundaries.
• Physically crossing the Karman Line does not result in substantial changes.
• In the immediate vicinity, there is minimal difference in air pressure or composition.
• Earth’s gravitational force remains influential, and the atmosphere persists beyond this line.

Why is the Karman Line relevant?

• Airspace Regulation: The Karman Line primarily serves as a regulator of airspace. It represents an approximate altitude beyond which conventional aircraft cannot operate effectively. Aircraft venturing beyond this threshold require propulsion systems to counteract Earth’s gravitational pull.
• Legal Reference: Additionally, the Karman Line acts as a legal benchmark that distinguishes airspace, which nations can claim ownership of, from the realm of outer space. Outer space is governed similarly to international waters, emphasizing the importance of this boundary in legal and governance contexts.

Central Idea

• The NASA OSIRIS-REx mission has achieved a significant milestone by successfully returning to Earth with an estimated 250 grams (8.8 ounces) of material gathered from the surface of an asteroid.
• These precious samples hold the potential to provide critical insights into differentiating authentic asteroid-origin materials from potential terrestrial contaminants or alterations across various meteorite types.

OSIRIS-REx Mission

(a) Mission Launch and Journey:

• OSIRIS-REx embarked on its journey when it was launched from Cape Canaveral, Florida, in 2016.
• Over a span of two years, it traversed space to reach Bennu, a carbon-rich asteroid nestled between Earth and Mars.

(b) Orbiting Bennu:

• The spacecraft reached its destination, Bennu, in December 2018.
• It spent two years in orbit around the asteroid, conducting a comprehensive suite of measurements.
• These measurements encompassed critical aspects such as Bennu’s mass, density, albedo, surface composition, and particle environment.
• The landing site chosen on Bennu was named “Nightingale.”

(c) Notable Discoveries:

• During the reconnaissance phase, the OSIRIS-REx mission uncovered several intriguing findings:
• Bennu is classified as an active asteroid, periodically ejecting material from its surface.
• The surface of Bennu exhibited a considerably rougher terrain than initially expected, featuring numerous boulders exceeding ten meters in diameter.
• Bennu’s bulk density was found to be lower than anticipated, suggesting the presence of substantial empty space within the asteroid’s structure.
• Surface features on Bennu indicated signs of past aqueous activity, and the asteroid’s rotation was observed to be accelerating due to the YORP effect.

Previous such missions

• Previous space missions like Japan’s Hayabusa and Hayabusa2, as well as China’s Chang’e 5, have made substantial contributions to our understanding of celestial bodies and their compositions.
• The return of asteroid samples by OSIRIS-REx marks NASA’s first sample return mission since Stardust in 2006 and Genesis in 2004.

Significance of Sample Return

• The return of material directly from celestial sources, such as asteroids, comets, the solar wind, and the Moon, holds immense scientific significance.
• It provides the means to answer questions that lie beyond the scope of remote observations, landers, rovers, or even meteorites.
• Collecting samples directly from the source ensures the preservation of intricate details that may otherwise be lost during a meteorite’s passage through Earth’s atmosphere and subsequent impact.

Central Idea

• A research utilized seismic data collected between 1976 and 1977, showcasing how the lunar lander left by the Apollo 17 astronauts might be causing seismic activity on the moon.
• The study emphasizes that these moonquakes are not the result of natural processes but stem from vibrations generated by the lunar module descent vehicle, which was placed on the moon’s surface in 1972.

About Apollo 17 Mission

• Apollo 17 was the final Apollo mission to the Moon, marking the sixth lunar landing.
• It was launched by December 6, 1972, with a night launch, which was unique in the Apollo program.
• This mission had specific scientific objectives, differentiating it from previous missions, and aimed to collect ancient highlands crustal material and investigate the possibility of recent lunar volcanic activity.
• Neil Armstrong, the first person to set foot on the lunar surface, went under the Apollo 11 mission in July 20, 1969.

Understanding Moonquakes

• Similarities to Earthquakes: Moonquakes share similarities with earthquakes as both involve seismological vibrations.
• Researchers have identified four types of moonquakes, three of which are relatively benign. Shallow moonquakes, the closest to the surface, are the most destructive.

1. Deep Moonquakes: Occur approximately 700 kilometers below the lunar surface.
2. Shallow Moonquakes: Take place at depths of only 20 to 30 kilometers, lasting up to 10 minutes.
3. Vibrational Moonquakes: Typically result from meteorite impacts.
4. Thermal Quakes: Caused by the moon’s crust expanding as it warms following subzero temperatures during the night.

• Moonquakes occur as often as every 27 days, primarily due to temperature fluctuations between lunar day and night, totalling approximately 7,000 moonquakes in a decade.

Moonquakes vs. Earthquakes

• Moonquakes are generally smaller in magnitude than earthquakes but are known for their extended duration.
• Shallow moonquakes recorded by Apollo astronauts have reached up to a magnitude of 5.5.

Human Lunar Landings

• Multiple countries have embarked on lunar missions, with India being the most recent in 2023, following the United States, Russia, and China.
• India’s Chandrayaan-3 mission included a seismometer, which detected a moonquake, providing valuable data for future analysis.

Significance of Monitoring Moonquakes

• Understanding moonquakes holds potential significance for future lunar missions, particularly if NASA establishes a permanent lunar outpost.
• Seismometers, like those used on the moon, are vital for comprehending lunar geology and ensuring the safety of future lunar explorers.
• Monitoring lunar seismic activity is crucial for designing experiments and missions aimed at unravelling the mysteries of Earth’s closest celestial neighbor.
• The moon presents a unique opportunity for in-depth planetary study beyond Earth.

Central Idea

• A recent revelation from the Solar Orbiter Aircraft, a collaborative endeavour between the European Space Agency and NASA, has illuminated the Picoflare jets erupting from the sun’s outer atmosphere.
• These jets, marked by their supersonic emergence and brief durations of 20 to 100 seconds, have captured the attention of scientists and space enthusiasts alike.

What are Picoflare Jets?

• Picoflare jets, observed amidst emissions from the observed coronal hole, are diminutive in scale but pack a potent punch.
• Their ephemeral existence belies their significance, as scientists have calculated that they contribute a substantial portion of the solar winds’ energy.
• These solar emanations earned their name, “picoflare jets,” owing to their energy levels, which hover around one-trillionth of the solar flares’ immense energy potential.
• Solar winds, driven by strong gusts, can not only craft auroras in Polar Regions but also disrupt Earth’s magnetic field and jeopardize electronic systems on satellites and terrestrial circuits.

About Solar Orbiter Aircraft

• A Stellar Journey: Launched in 2020, the Solar Orbiter Aircraft embarks on a mission to capture unprecedented images of the Sun, propelling closer than any previous spacecraft.
• Instrumentation Excellence: Equipped with six remote-sensing instruments and four sets of in situ instruments, the spacecraft is primed for comprehensive solar exploration.
• Mission Objectives: The Solar Orbiter Aircraft carries two primary objectives: to scrutinize the Sun’s 11-year cycle of magnetic activity ebbs and flows and to delve into the mysteries of the solar corona, the upper echelon of the Sun’s atmosphere.

Central Idea

• Two Japanese astronomers have uncovered potential evidence of an “Earth-like planet” within our solar system.
• This mysterious planet is believed to have resided in the Kuiper Belt, a circumstellar disk beyond Neptune’s orbit that consists of outer solar system objects.
• The Kuiper Belt, like the planets, orbits the Sun.

What is the Kuiper Belt?

• The Kuiper Belt, also known as the Edgeworth-Kuiper belt, is a flat ring of small icy bodies orbiting the Sun beyond Neptune’s orbit.
• Gerard Kuiper, a Dutch-American astronomer, first hypothesized its existence in the 1950s.
• This belt contains millions of icy objects, collectively referred to as Kuiper Belt objects (KBOs) or trans-Neptunian objects (TNOs).
• It is considered a remnant from the early history of our solar system.
• The Kuiper Belt is thought to be the source of many short-period comets that orbit the Sun in less than 20 years.
• It primarily consists of small icy bodies, including dwarf planets, asteroids, and comets.
• Pluto, once classified as the ninth planet, is one of the most well-known objects in the Kuiper Belt but was reclassified as a dwarf planet by the International Astronomical Union (IAU) in 2006, partly due to its location within this belt.

The Astronomers’ Findings

• The Japanese researchers suggest that if this new planet exists, it would be 1.5 to 3 times the size of Earth.
• The discovery challenges previous theories of a distant “Planet Nine” and posits the possibility of a planet closer to us, within the Kuiper Belt.
• The astronomers predict the existence of an Earth-like planet and several trans-Neptunian objects (TNOs) on unique orbits that could serve as observational signatures of this potential planet’s perturbations.
• They estimate that this planet could be situated between 200 and 500 astronomical units (AU) from the Sun, tilted about 30 degrees. For reference, Pluto is 39 AU from Earth.

Central Idea

• Researchers from India and the US have come up with a new way to answer a big question about the universe.
• This question is about how fast the universe is getting bigger.

Story of Our Universe

• The universe began around 13.8 billion years ago with a massive explosion called the Big Bang.
• As time passed, the universe kept getting bigger, with moments of speeding up and slowing down.
• Scientists want to understand this expansion to figure out what’s happening in the universe.

Hubble Constant: A Big Question

• The Hubble constant is a special number that tells us how quickly the universe is expanding.
• This number was first talked about by a scientist named Edwin Hubble in 1929.
• But scientists today are still not sure about its value.

Two Important Things to Measure

To know the Hubble constant, we need to measure two things carefully:

1. How far away things in space are from us.
2. How fast these things are moving away from us because of the universe’s expansion.

Old Ways vs. New Idea

Until now, scientists used a few methods to measure the Hubble constant:

• Looking at bright explosions in space called supernovae.
• Using special light from the early universe.
• Studying waves created by big crashes in space.

But now, a fresh idea has been propounded by Indian researchers:

• To measure using a thing called “gravitational lensing.”

Gravitational Lensing: A New Approach

• Gravitational lensing is like bending light using gravity. Imagine it like a magnifying glass in space.
• This idea came from a long time ago but got better recently.
• Scientists think they can use this lensing trick to measure the Hubble constant.
• They want to look at waves from space collisions that get bent by gravity.
• These bent waves could tell us about how fast the universe is expanding.

The Big Idea: A Bridge between Time

• This new idea is cool because it connects different times in the universe’s history.
• It could give us a good answer about the Hubble constant.

Challenges

• While this idea is exciting, there are some challenges to solve:

• 1. Making sure the signals are clear enough to measure.
  2. Using the new method to answer other questions too.
• If this new way works, it could help us learn about things like dark matter and other universe stuff.