Source: HINDU 

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Context

Recently, three Australian CubeSats from Curtin University’s Binar Space Program burned up in the Earth’s atmosphere much sooner than expected due to increased solar activity.

The Sun’s Activity and Solar Cycles

The Sun’s activity, governed by its magnetic cycle, affects not just the Earth but also satellites orbiting close.

Sun undergoes an 11-year solar cycle during which its magnetic field flips. It leads to varying solar activity. 

Features:

Sunspots: Dark spots on the Sun’s surface caused by magnetic disturbances.

Solar Flares: Intense bursts of energy from the Sun.

Solar Wind: Streams of charged particles emitted by the Sun.

Solar Cycle 25:

This cycle began in December 2019.

Solar activity has recently been 1.5 times higher than predicted, peaking earlier than expected.

The Sun’s activity will likely slow by 2026 with a solar minimum expected by 2030.

How Solar Activity Affects Space Weather

Space weather refers to environmental effects originating from outside Earth’s atmosphere, mostly from the Sun.

Auroras:

 Increased solar activity results in more visible auroras even closer to the equator.

Impact on Satellites:

Charged Particles can damage electrical components.

Ionizing Radiation disrupts long-distance radio communication.

Solar energy heats the outer atmosphere, causing it to expand, increasing atmospheric drag on satellites.

Astronauts and Pilots:

Higher doses of ionizing radiation are experienced, posing health risks.

Low Earth Orbit

Low Earth Orbit (LEO), at altitudes less than 1,000 km, is where most satellites experience the impact of increased solar activity.

Increased Drag in LEO:

When the atmosphere expands, satellites face stronger resistance, pulling them closer to Earth.

International Space Station (ISS) and Starlink satellites have thrusters to counteract drag but CubeSats usually don’t.

Binar Space Program

The program, based at Curtin University focuses on advancing knowledge of the Solar System and making space operations more accessible.

Binar-1 Satellite:

Launched in September 2021 during low solar activity in solar cycle 25.

Small satellite (10 cm cube) orbited at 420 km.

Successfully completed 364 days in orbit.

Binar-2, 3 and 4:

The program launched these CubeSats designed to last six months. Due to high solar activity they burned up in just two months reducing their scientific mission duration.

Read about Solar Activity in detail: IAS GYAN

Sources:

HINDU

 

PRACTICE QUESTION Q.Which of the following statements about sunspot cycles is/are correct? The Sun undergoes an 11-year cycle of solar activity during which the number of sunspots varies. A solar maximum refers to the period of the cycle when sunspot numbers are lowest. Sunspot activity can influence Earth’s climate patterns. Options: a) 1 only b) 1 and 3 only c) 2 and 3 only d) 1, 2, and 3 Answer: b)  Explanation: Statement 1 is correct: The Sun follows an 11-year cycle alternating between solar minimum (low activity) and solar maximum (high activity with many sunspots). Statement 2 is incorrect: A solar maximum is the peak of sunspot activity not the lowest point. Statement 3 is correct: Sunspot activity can influence Earth's climate by slightly altering solar irradiance and affecting atmospheric conditions.