Vanguard 1: The Oldest Satellite Still in Orbit
Vanguard 1, launched on 17 March 1958, holds the distinction of being the oldest human-made satellite still in orbit. It was part of the United States' response to the Soviet Union's Sputnik programme, marking a significant milestone in the early space race. This small satellite, weighing just 1.47 kilograms, was designed by the Naval Research Laboratory and was intended to test the capabilities of a three-stage launch vehicle and to study the effects of the environment on a satellite in orbit. Its successful deployment demonstrated the feasibility of satellite tracking and communication from space.
The primary mission of Vanguard 1 was to test the launch capabilities of the Vanguard rocket and to collect geophysical data. It carried a small transmitter that operated on two frequencies, enabling scientists to track its orbit and gather information about the Earth's shape and density. Vanguard 1's mission contributed to the understanding of the Earth's atmosphere by providing data on air density at high altitudes. Although its transmitters only functioned for a few months, the satellite's impact on space science was profound, laying the groundwork for future satellite missions.
Vanguard 1 was inserted into a highly elliptical orbit with an initial perigee (closest point to Earth) of 654 kilometres and an apogee (farthest point) of 3,969 kilometres. Its orbit has an inclination of 34.25 degrees, which means it travels over a wide range of latitudes. The satellite completes an orbit around the Earth approximately every 134 minutes. Its NORAD ID is 00005, a testament to its early entry into the catalogue of space objects. Despite the passage of time, Vanguard 1 remains in orbit, its trajectory gradually altered by gravitational perturbations and atmospheric drag.
Vanguard 1's successful launch and operation provided critical insights into satellite technology and Earth's environment, influencing subsequent space missions. It was the first satellite to use solar cells for power, a technology that has become standard in space exploration. The data collected from Vanguard 1 helped refine our understanding of the Earth's shape, leading to more accurate geodetic measurements. Its longevity in orbit serves as a reminder of the durability of early space technology and the enduring legacy of the pioneering era of space exploration.
As of 2026, Vanguard 1 remains in orbit, making it the oldest satellite still circling the Earth. Although it no longer transmits data, its presence is a valuable tool for studying the long-term effects of space weathering and orbital decay. The satellite's trajectory can be monitored using tools like the Orbital Radar satellite tracker, which provides real-time data on its position and orbit. Vanguard 1 is expected to remain in orbit for many more decades, a silent witness to the evolution of space technology.
