The French novelist Jules Verne delighted 19th-century readers with the idea that a journey to the centre of the Earth was actually plausible.

Since then, scientists have recognised that Verne's literary voyage was only science fiction. The extreme temperatures of the Earth's interior (about 10,000 degrees Fahrenheit (5,537 Celsius) in the core) and the accompanying crushing pressure, millions of times greater than on the surface, prevent humans from travelling very far.

Still, a few things are known about the Earth's interior. For example, geophysicists have discovered that the core consists of a solid sphere of iron and nickel that makes up 20 per cent of the Earth's radius and is surrounded by a shell of molten iron and nickel that covers 15 per cent of the Earth's radius.

This and the rest of our knowledge of the Earth's interior has been learnt indirectly, by studying the Earth's magnetic field or the way earthquake waves are reflected from different layers beneath the Earth's surface.

But indirect discovery has limitations. How can scientists learn more about the deep interior of our planet?

Planetary scientists believe that the best way to learn about Earth's interior is from outer space.

NASA's robotic mission to a metal world is scheduled to launch on 5 October 2023. The mission, the spacecraft that will go there and the world it will explore have the same name: Psyche. You know this name comes from mythology, don't you? Psyche, the love of Cupid.

Psyche asteroidi hakkında

Asteroitler küçük dünyalardır, bazıları küçük şehirler bazıları ise küçük ülkeler kadar büyüktür. Bunlar Güneş Sistemimizin erken ve şiddetli döneminden, gezegen oluşumu zamanından arta kalan yapı taşlarıdır.

Çoğu kayalık, buzlu veya her ikisinin bir kombinasyonu olsa da, asteroitlerin belki de yüzde 20'si metalden yapılmış ve bileşim olarak Dünya'nın çekirdeğine benzer dünyalardır.

Dolayısıyla bu metalik asteroitlerin, bir zamanlar var olan gezegenlerin çekirdeklerinin, birbirleriyle olan eski kozmik çarpışmalarla parçalanmış parçaları olduğunu hayal etmek cazip geliyor. Belki de bilim insanları bu parçaları inceleyerek bir gezegenin çekirdeğinin nasıl bir şey olduğunu doğrudan öğrenebilirler.

Psyche metalik asteroitlerin bilinen en büyüğüdür. 1852'de keşfedilen Psyche, Massachusetts kadar genişliğe, iğneyi andıran ezilmiş küresel bir şekle ve ana asteroit kuşağında Mars ile Jüpiter arasında bir yörüngeye sahiptir. Amatör bir gökbilimci Psyche'yi bir arka bahçe teleskobuyla görebilir, ancak yalnızca bir ışık noktası olarak görünür.

About the Psyche mission

In early 2017, NASA approved a $1 billion mission to Psyche. To do its job, the uncrewed spacecraft does not need to land. Instead, it will repeatedly and methodically orbit the asteroid, starting at a distance of 435 miles (700 kilometres) and then descending to 46 miles (75 km) from the surface and perhaps even lower.

When it arrives in August 2029, the probe will spend 26 months mapping the asteroid's geology, topography and gravity; looking for evidence of a magnetic field; and comparing the asteroid's composition with what scientists know, or think we know, about Earth's core.

The key questions are: Is Psyche really an exposed planetary core? Is the asteroid a large chunk of bedrock, a rubble pile of smaller rocks, or something else entirely? Are there clues that the former outer layers of this small world - the crust and mantle - were violently peeled away long ago? And perhaps the most critical question: Can what we learn about Psyche be extrapolated to solve some of the mysteries about the Earth's core?

About the spacecraft Psyche

The probe's body is about the same size and mass as a large SUV. Its solar panels, slightly larger than a tennis court, power cameras, spectrometers and other systems.

A SpaceX Falcon Heavy rocket will take Psyche out of Earth. The rest of the way, Psyche will rely on ion propulsion - the gentle pressure of ionised xenon gas spewing from a nozzle provides a continuous, reliable and low-cost way to propel the spacecraft through the Solar System.

The journey, a slow spiral of 2.5 billion miles (4 billion km) that includes a gravity-assisted flyby of the side of Mars, will take about six years. During the journey, the Psyche team at NASA's Jet Propulsion Laboratory in Pasadena, California, and here at Arizona State University in Tempe will be in regular contact with the spacecraft. The team will send and receive data using NASA's Deep Space Network of giant radio antennas.

Even if we find out that Psyche is not an ancient planetary nucleus, it will add significantly to our knowledge of the solar system and the formation of planets. After all, Psyche is unlike any world humans have ever visited.

We may not be able to travel to the centre of the Earth yet, but robot avatars travelling to places like Psyche could help unlock the mysteries hidden deep within planets, including our own.

 

Source: https://www.sciencealert.com/