NASA’s LEXI Makes Way To Capture First Global Images of Earth’s Magnetic Field

As part of NASA’s Artemis campaign, The Lunar Environment Heliospheric X-ray Imager, aka LEXI, an X-ray imager is on its way to the Moon to take the first worldwide pictures of the Earth’s Magnetic Field that protects from solar radiation.

Firefly Aerospace’s Blue Ghost Lander is scheduled to launch from the agency’s Kennedy Space Center in Florida no earlier than mid-January as per NASA.

You’re probably wondering how or why NASA ended up here. Well, we do have all the answers for why NASA is trying to capture the images of Earth’s Magnetic shield, but first lets enlighten you on what Earth’s Magnetic Field is or why does earth have a magnetic field.

What is Earth’s Magnetic Field?

Earth’s magnetic field, also known as the geomagnetic field, is a magnetic dipole that extends from the Earth’s interior out into space, enveloping the planet in a protective shield. Here’s an overview of its key aspects:

Nature & Origin

• Dynamo Theory: The magnetic field is believed to be generated by electric currents in the molten outer core of the Earth. The movement of molten iron and nickel within this layer creates electric currents through a process known as the geodynamo.
• Magnetic Poles: The field emerges from the Earth’s south magnetic pole, loops around in space, and re-enters at the north magnetic pole. Note that the north magnetic pole is where the field lines enter the Earth, which is why it’s attracted to the north pole of a compass needle (opposite poles attract).

Characteristics

• Magnetic North and South: These poles do not align perfectly with the geographic North and South poles; the magnetic north pole is currently in the Arctic Ocean, off the coast of Canada, and it wanders over time.
• Field Strength: The strength of the Earth’s magnetic field varies from place to place but is on average about 0.5 gauss (50 microteslas) at the surface.
• Magnetic Reversals: Over geological time scales, the magnetic field has reversed its polarity many times, an event known as a magnetic field reversal. The last reversal was about 780,000 years ago.

Effects and Importance

• Protection from Cosmic Radiation: The magnetic field deflects charged particles from the solar wind, preventing them from stripping away Earth’s atmosphere and exposing life to harmful radiation.
• Auroras: When charged particles do enter the magnetic field, they can create auroras (Northern and Southern Lights) by colliding with atoms in the atmosphere.
• Navigation: It has been used for navigation since ancient times with the compass, and today, it’s crucial for various technologies including satellite navigation systems.

Components

• Main Field: Generated by the dynamo in the core.
• Crustal Anomalies: Local variations in the magnetic field due to magnetized rocks in the Earth’s crust.
• External Field: Influenced by solar activity, which can temporarily distort the Earth’s magnetic field.

Earth’s magnetic field is not only a fascinating natural phenomenon but also vital for life as we know it, providing a protective shield while simultaneously offering clues about the planet’s internal structure and history.

But Why does Earth have a Magnetic field?

Earth has a magnetic field primarily due to the dynamo process occurring in its molten outer core. Here’s an explanation of why this happens:

1. Core Structure

• Inner Core: Solid, primarily made of iron.
• Outer Core: Liquid, consisting of molten iron and nickel. This layer is where the magnetic field originates.

2. The Dynamo Effect:

• Convection: Heat from the Earth’s inner core causes convection currents in the liquid outer core. As the Earth rotates, these currents move, creating complex motions of the molten metal.
• Electric Currents: The movement of this conductive fluid results in electric currents. According to Faraday’s law of electromagnetic induction, these currents generate magnetic fields.

3. Rotation of the Earth:

• The Earth’s rotation plays a crucial role. It causes the Coriolis effect on these fluid motions, which helps in generating a self-sustaining magnetic field. The Coriolis effect twists the fluid flow into spirals, enhancing the dynamo process.

4. Magnetic Field Amplification:

• The magnetic field generated by these currents can then amplify itself through a feedback loop where the magnetic field influences the fluid motion, which in turn affects the magnetic field. This self-sustaining process is key to maintaining the magnetic field over geological timescales.

5. Thermal and Compositional Convection:

• Besides rotation, there’s also thermal convection due to the heat from the core, and compositional convection due to the solidification of the inner core (which releases lighter elements into the liquid outer core, causing buoyancy).

Importance of the Magnetic Field:

• Protection: It shields the Earth from solar wind and cosmic rays, which could otherwise strip away the atmosphere and harm life.
• Navigation: It’s essential for compass navigation and satellite operations.
• Geological Record: The magnetic field leaves a record in rocks as they form or cool, providing scientists with information about past magnetic field strengths and reversals, thus aiding in understanding Earth’s history.

So, Why Not All Planets Have Magnetic Fields?

• The presence of a magnetic field requires a few conditions:
  • A liquid outer core.
  • Sufficient rotation.
  • Convection within the core.

Planets like Mars, which have cooled down significantly, lack an active dynamo due to their solid core or insufficient internal heat for convection.

In summary, the Earth’s magnetic field exists because of the complex interaction of its internal structure, rotation, and the dynamo process in the outer core, which together create a self-sustaining magnetic field around our planet.

Now, lets get back to where we started.

Why is NASA keeping an eye on EARTH’s Magnetic Field?

South Atlantic Anomaly, a large portion of earth’s magnetic field has stretched above our planet. This is not any tiny dent we are talking about. The anomaly that has kept scientists wondering for years, stretches from South America to southwest Africa.

Spaceship or satellites experience a weak magnetic field when they hover around these region. It means, these shuttles embraces the exposure of charged particles from the sun which causes a malfunction inside potentially leading to short circuit.

Spacecraft routinely shuts down it’s system when they are about to enter this perimeter.

While it may not be harmful over the surface, the SAA certainly creates an unfavorable environment for these vehicles up in the sky!

NASA’s Artemis campaign focuses on capturing the images of this dent with the help of LEXI from lunar surface.

LEXI On It’s Way To Capture Earth’s Magnetic Field

NASA’s X-ray imager will shift its’ focus to the home planet once the dust clears from the moon landing. It is projected that Lexi will collect the images for six days.

The images obtained from Artemis campaign will help to enlighten on how this magnetosphere will respond to space weather and other cosmic forces. Besides, we may also be able to learn on how these charged particles at SAA occurs, that will ultimately help the cause – minimizing the threats to our infrastructures. 

“We’re trying to get this big picture of Earth’s space environment,” said Brian Walsh, a space physicist at Boston University and LEXI’s principal investigator. “A lot of physics can be esoteric or difficult to follow without years of specific training, but this will be science that you can see.”

LEXI’s low-energy X-rays will focus on when and how the stream of particles slams into Earth’s magnetosphere from the Sun.

This won’t be LEXI’s first trip to the space. Back in 2012, a team of Goddard -a lead science collaborator on LEXI, and Walsh launched the instrument (then called STORM), to detect low-energy X rays over a wide field.

Goddard held those images in a display case for a decade until NASA called out for Commercial Lunar Payload Services (CLPS) project that could be done with a limited budget and efficiently.