Cosmic Particle Accelerator Near Earth

Sub : Sci

Sec: Space sector

Why in News

Recent research has provided crucial insights into one of astrophysics’ long-standing mysteries—how subatomic particles, such as electrons, attain ultra-high energy in space. Using data from NASA’s Magnetospheric Multiscale (MMS) mission, the THEMIS mission, and the ARTEMIS mission, scientists observed an extraordinary energy surge in electrons within Earth’s foreshock region.

Details:

One of the major unsolved questions in astrophysics is how electrons travel vast distances and acquire extreme energy.
The study suggests that collision less shock waves, commonly found in space, serve as natural particle accelerators.
These shock waves were detected in the Earth’s foreshock, the region where the solar wind collides with the planet’s magnetosphere.
Plasma, a state of matter composed of charged particles, plays a crucial role in this acceleration process.
Unlike sound waves in the atmosphere, shock waves in plasma transmit energy through electromagnetic forces rather than particle collisions.
Such waves are prevalent near celestial bodies like pulsars, magnetars, and black holes.
The findings suggest that shock waves in plasma may be responsible for generating cosmic rays, which are high-energy particles that travel through space.
Traditionally, supernova shocks have been considered the primary sources of cosmic rays, but this study introduces the possibility that planetary shock waves may contribute as well.

About Shock Waves:

A shock wave is a type of propagating disturbance that moves faster than the local speed of sound in a medium.
It is characterized by an abrupt change in pressure, temperature, and density of the medium.
Shock waves are strongly irreversible processes, leading to an increase in entropy and a decrease in the energy that can be extracted as work.
Examples: The sonic boom heard as a supersonic aircraft passes is due to shock waves.

Electrons in Foreshock and Bow Shock Regions:

Bow Shock: The bow shock is the area where the solar wind—a stream of charged particles emitted by the Sun—slows down abruptly upon encountering Earth’s magnetosphere.
Foreshock: The foreshock is the region upstream of the bow shock, characterized by turbulent magnetic fields and reflected particles.
It’s a zone where particles from the solar wind interact with Earth’s magnetic field before reaching the bow shock.
Electron Acceleration: In the foreshock region, electrons can gain significant energy through interactions with plasma waves and magnetic field fluctuations.
These accelerated electrons can reach speeds close to that of light.
Understanding electron dynamics in these regions is crucial for insights into space weather, which can impact satellite operations, communication systems, and power grids on Earth.

Magnetospheric Multiscale (MMS) Mission:

To study magnetic reconnection in Earth’s magnetosphere, a process where magnetic fields from different sources connect and release energy.
Consists of four identical satellites flying in a tetrahedral formation to provide three-dimensional observations.
Launched in 2015, aboard an Atlas V 421 rocket.
First direct detection of magnetic reconnection in Earth’s magnetosphere in 2016.
Observed magnetic reconnection in the magnetosheath in 2018, a region previously considered too turbulent for such events.

Time History of Events and Macroscale Interactions during Substorms (THEMIS) Mission:

To investigate the onset of substorms in Earth’s magnetosphere, which are brief disturbances causing auroras and affecting space weather.
Originally consisted of five identical satellites (THEMIS-A through THEMIS-E) placed in various Earth orbits to monitor different regions of the magnetosphere.
Launched in 2007, aboard a Delta II rocket.
Identified the location and timing of substorm onsets, linking them to magnetic reconnection events in the magnetotail.

Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) Mission:

To study the Moon’s interaction with solar wind and Earth’s magnetosphere, focusing on phenomena like plasma acceleration, magnetic reconnection, and turbulence.
Repurposed two of the original THEMIS satellites (THEMIS-B and THEMIS-C) into lunar orbiters, renamed ARTEMIS-P1 and ARTEMIS-P2.
The transition from Earth orbit to lunar orbit began in 2009, with both spacecraft successfully entering lunar orbit in 2011.
Conducted the first simultaneous two-point measurements of the lunar environment.
Studied how the Moon’s presence affects Earth’s magnetotail and plasma sheet.