Read the passage and answer the questions: Scientists know f…

Reаd the pаssаge and answer the questiоns: Scientists knоw far mоre about distant planets and outer space than they do about what lies beneath their own feet. For decades, researchers have attempted to explore the Earth’s interior, yet drilling deep into the planet has proven far more difficult than launching spacecraft into orbit.During the Cold War, scientific rivalry between the United States and the Soviet Union extended beyond the Space Race. While both nations competed to dominate space exploration in the 1950s and 1960s, a lesser-known but equally ambitious contest was unfolding underground. Geologists from both countries sought to drill deeper into the Earth’s crust than ever before in order to uncover the secrets hidden beneath the surface.At first glance, rocks and soil may seem far less intriguing than the cosmos. However, scientists recognized that the Earth’s crust could reveal valuable information about the planet’s structure, history, and composition. Boreholes are typically drilled for oil or gas, but these projects were purely scientific, intended to explore the boundaries between the Earth’s layers. The Earth consists of several layers, beginning with the crust, a rocky shell that extends roughly 20 miles deep. Beneath the crust lies the mantle, a massive and mysterious layer that has never been reached by drilling. Because continental crust is thick and ancient, early efforts focused on drilling through the thinner oceanic crust, which measures only four to six miles deep.In the early 1960s, American scientists launched Project Mohole off the coast of Mexico. Their goal was to reach the boundary between the crust and the mantle, known as the Mohorovičić discontinuity, or “moho.” Despite initial success, the project became increasingly expensive and was ultimately abandoned in 1966, having drilled only 601 feet into the crust. This failure gave Soviet scientists an opportunity to take the lead.In 1970, the Soviet Union began drilling into the continental crust of the Kola Peninsula in northern Russia. The project, known as the Kola Superdeep Borehole, aimed to drill as deeply as technology would allow. Unlike the American project, the Soviets persisted for decades, continuously upgrading their equipment and methods.By the late 1970s and early 1980s, the Soviets repeatedly broke world records for drilling depth. At its deepest point, the borehole reached 40,230 feet, or 7.5 miles into the Earth. However, extreme temperatures and intense pressure caused unexpected problems. The rock behaved less like solid stone and more like plastic, making drilling nearly impossible. Equipment warped, and the borehole began closing in on itself whenever drilling stopped.     Despite these challenges, the project produced groundbreaking discoveries. Scientists found microscopic fossils nearly four miles below the surface, providing evidence of ancient biological life. They also discovered that the crust in the Kola region consisted entirely of granite, contradicting previous theories that granite gradually transitions into basalt. Even more surprising was the presence of water deep underground, formed by chemical reactions under immense pressure.Ultimately, the combination of technical difficulties, rising costs, and the collapse of the Soviet Union led to the project’s abandonment. Drilling ceased in 1992, and the site was permanently sealed in 1995. Although the borehole reached only a tiny fraction of the distance to the Earth’s core, it remains the deepest man-made hole on the planet. The Kola Superdeep Borehole transformed scientists’ understanding of the Earth’s interior and demonstrated the limits of human technology. While the site today appears abandoned and sealed, its legacy continues to influence geological research. More than fifty years later, scientists remain driven by the same curiosity that inspired this extraordinary attempt to explore what lies beneath the Earth’s surface. According to the passage, why is exploring the Earth’s interior more difficult than exploring space?