Will humans be able to send robots to the core of the earth?

A scientist from California is trying to develop an idea brought up in a Hollywood thriller - to send a robotic vehicle to the center of the Earth (well, in the thriller the vehicle was manned)

Earth's layers. Illustration - the weekly Nature

Actress Hilary Swank isn't the only one who wants to ride a terra-ship to the molten center of the Earth. In the thriller in which Seong stars, "The Core", a researcher from California intends to send a vehicle that will ride on waves of molten iron on a week-long journey to the center of the earth.
Caltech geologist David Stevenson, this time not in the movie but in reality, knows that his proposal is unacceptable, but since billions of dollars are found on space exploration every year, he says, and the interior of our equally mysterious planet deserves a similar study.
The Earth's core creates the magnetic fields that keep the compasses pointing north and prevent the deadly radiation from space from reaching the Earth's surface. The scientists know from the seismic data that the core is solid and its outer edge is molten, but many questions still remain open.
"We will learn about the Earth, which is after all the planet we live on, about the composition of its core, the temperature in the core. These questions are the most exciting," says Stevenson, whose proposal appeared in the journal Nature. "These questions have implications for why Earth has a magnetic field, and why it persists for so long."
"The process of launching a spacecraft to the center of the earth will resemble a volcano, upside down," Stevenson said. The unmanned, grapefruit-sized craft will have to be built so it can withstand the heat that causes iron to melt as well as the immense pressure at the center of the Earth. The tool will contain devices for measuring temperature, electrical conductivity and chemical composition. The device will send the data as sound waves to a detector on the surface, which will filter the signals from the Earth's natural bustle.
Starting the crack will be the tricky part, Stevenson says. He calculated that an explosion equivalent to several megatons of TNT would be needed, something equivalent to a magnitude 7 earthquake. The device will have to descend to a depth of 2,900 kilometers to the molten iron layer. The center of the earth is at a depth of 6,335 kilometers from the surface of the earth.
The development of these vehicles will require efforts similar to that of the Manhattan Project - within the framework of which the first atomic bomb was built during World War II, says Stevenson. While this may not happen, the researchers hope that the proposal will at least get people thinking about other, better ways to explore the center of the Earth. Other geologists said Stevenson's plan was impractical, but inspired. Stevenson is aware that large parts of his proposal are futurist. "I don't mind if some people think the show is funny, but I'd be happy if some people check it out and take it seriously."
strike with the iron while it is hot

By Kenneth Chang

The proposal to send a robot to the Earth's core is far-fetched, but not scientifically ridiculous
The premise behind "Core The" the last film in the stupid genre of "Earth in danger" movies, is perhaps not completely stupid. At the very least, this film prompted Dr. David Stevenson, professor of earth sciences at the California Institute of Technology (CalTech), to put into writing some ideas that have been floating around in his head for decades.

Last year, the creators of "The Core" asked Stevenson to talk to journalists about the scientific principles underlying the film (the gist of the plot: the Earth's core stops rotating, and this causes electrical storms to erupt, the collapse of the Golden Bridge and the death of people with pacemakers.
The heroes of the film go to the center of the earth to restart the core). Stevenson agreed to the filmmakers' request, but his comments were rather skeptical. He also spent a day writing a paper on the possibility of sending a scientific research unit to the Earth's core. "It was kind of a joke," Stevenson said. "To a certain extent, it's still kind of a joke."

The article he wrote passed the criticism of his fellow scientists and appears in the current issue of the journal "Nature." Despite the wild imagination invested in it, Stevenson says the proposal is "not ridiculous" and is based on known scientific principles.

Stevenson's article suggests reversing the natural order of things. In nature, molten magma rises through cracks to the surface and erupts from volcanoes.
To move to the core, suggests Stevenson, a crack in the ground must be opened and at least 100 tons of hot liquid iron must be poured into it. The weight of the iron will open an opening at the bottom of the crack, through which the liquid iron can flow in. "You just have to press on the rock walls," Stevenson said. "From the moment you take the first step, the Earth does everything else."

The robot that will be sent down will be a ball made of an alloy that has been melted at a high temperature. Its size will be between that of a grapefruit and that of a basketball. The alloy ball will float in the center of the iron pool.

Geologists have not yet been able to peer directly into the bowels of the earth. The Russians hold the record for the deepest drilling, 12 km, but this depth does not even pierce the hard outer crust of the Earth.
Almost everything known about the mantle beneath the outer crust, the outer core made of liquid iron, and the solid inner core, is derived from patterns of magnetic fields and seismic waves observed on Earth's surface.

As it progresses through 2,900 km of Earth's mantle, Stevenson's research robot will be able to measure temperature, mineral composition and magnetic fields until it drifts into the liquid outer core. "It's a hot, crazy, provocative idea," said Dr. Raymond Ginluz, a professor of geology at the University of California, Berkeley. "Such an experiment, if it were possible, would yield a scientific treasure".

The technical hurdles of such an experiment are great. It is necessary to carve electronic devices from diamond, which can operate at temperatures of 3,900 degrees Celsius and at a pressure more than a million times greater than the pressures existing on the surface of the earth. Another challenge is to develop special means of communication, since the rock blocks radio signals. Stevenson suggests using sound waves instead.

Scientists would also have to ask regulatory bodies to sign a far-reaching statement about the environmental impact of such an experiment. To open the initial crack - which will be about 300 meters long, 300 meters deep and at least 10 cm wide - energy equal to several million tons of explosives, an earthquake of magnitude 7 on the Richter scale or an atomic bomb will be required.
"Yes, of course you have to be careful," Stevenson said. But according to him, such an experiment would cost less than NASA's investment in space exploration. "I think if it costs less than ten billion dollars, we should do it."

New York Times
For information on the Nature website