On July 26, 1971, the United States launched the Apollo 15 mission, which became one of the most scientifically significant missions in the Apollo program. The mission was crewed by Commander David Scott, Lunar Module Pilot James Irwin, and Command Module Pilot Alfred Worden.

One of the mission's primary objectives was to explore the Moon's Hadley-Apennine region, which features a beautiful combination of mountains, rilles (channels), and the 1,100-meter deep Hadley Rille. This site was chosen because it allowed the astronauts to study both the lunar highland material and the younger basaltic mare material.

During their three-day stay on the lunar surface, Scott and Irwin conducted three extravehicular activities (EVAs), during which they collected a record-breaking 77 kilograms (170 pounds) of lunar samples. These samples provided valuable insights into the Moon's geological history and formation.

Another significant aspect of the Apollo 15 mission was the use of the first Lunar Roving Vehicle (LRV). The LRV allowed the astronauts to cover a much larger area and greatly enhanced their ability to explore and collect samples. Scott and Irwin drove the LRV a total of 27.9 kilometers (17.3 miles) across the lunar surface, setting a record that stood until the Apollo 17 mission.

While orbiting the Moon, Alfred Worden conducted the first deep space EVA, venturing outside the Command Module to retrieve film cassettes from the Service Module. This EVA, performed approximately 315,400 kilometers (196,000 miles) away from Earth, still holds the record for the "most isolated human being" in history.

The Apollo 15 mission also left behind a small aluminum sculpture called "Fallen Astronaut" on the lunar surface, along with a plaque bearing the names of 14 astronauts and cosmonauts who had died in the line of duty. This poignant tribute serves as a reminder of the bravery and sacrifices made in the pursuit of space exploration.

In summary, July 26 marks the anniversary of the launch of Apollo 15, a groundbreaking mission that significantly advanced our understanding of the Moon and showcased the incredible achievements of human space exploration.