The first artificial satellite in human history is Sputnik 1, launched by the former Soviet Union on Oct. 4, 1957. At that time, the United States, engaged in the Cold War with the Soviet Union, was shocked by the success of Sputnik 1. This is known as the "Sputnik shock." The United States made significant investments in the space sector, and on Jan. 31 of the following year, the U.S. Army successfully launched Explorer 1. Two months later, on March 17, the Vanguard 1, created by the Naval Research Laboratory (NRL), was sent into space.
Vanguard 1 is neither the world's first artificial satellite (Sputnik 1) nor the first artificial satellite of the United States (Explorer 1), but it holds a title that will be remembered in history. It is the honor of being the oldest satellite in the world. Explorer 1 re-entered the atmosphere in 1970 and burned up, but Vanguard 1 is still orbiting the Earth. In March of this year, it marked the 67th anniversary of its orbit around the Earth.
The United States is considering a plan to bring back the longest-serving satellite, Vanguard 1. Early this year, the American Institute of Aeronautics and Astronautics (AIAA) released a presentation reviewing the possibility of returning Vanguard 1. Researchers from the global consulting firm Booz Allen Hamilton noted that "the U.S. Space Force (USSF) could collaborate with the National Aeronautics and Space Administration (NASA) or take over the Vanguard 1 program to work with corporations on its retrieval," adding that "the NRL, which owns the satellite, is also considering such mission possibilities."
◇ Opportunity to test orbital service technology
Vanguard 1 lost contact with Earth after its last communication in May 1965. However, NRL and NASA continue to track the position of Vanguard 1. It orbits the Earth in an elliptical orbit, approximately 660 km at its closest point and about 3,822 km at its farthest point.
Matt Ville, an aerospace research analyst at Booz Allen Hamilton, said, "As the solar cell output falls below the power needed to operate the transmitter, Vanguard 1 has remained silent since 1964. However, its current location and orbit can be determined through publicly available tracking data, and precision confirmation is possible using high-resolution sensors."
Artificial satellites generally fall and burn up in the Earth's atmosphere once their lifespan is over. Just as airplanes experience air resistance when flying, satellites in orbit gradually deviate from their original orbit and eventually fall due to air resistance and the influence of solar magnetic waves.
Head of Team Seong Jae-dong from the Korea Aerospace Research Institute (KAI) said, "Generally, satellites at a relatively low altitude of around 500 km experience a drop in altitude of tens to hundreds of meters per day due to air resistance. While there is very little air in space, the speed at which satellites move in orbit can reach several kilometers per second, which can significantly affect those at around 500 km."
However, Vanguard 1 has not reached such a state. The time it takes for a satellite to fall into the atmosphere varies widely depending on its characteristics and altitude. For high-altitude satellites, it can take hundreds to thousands of years. Vanguard 1 is also expected to take approximately 2,000 years to fall, assuming there are no special external factors.
The Head of Team explained, "Vanguard 1 has a perigee of 650 km and an apogee of 3,800 km, so unless it maneuvers to change its orbit or is retrieved through close operations, it is likely to maintain its current orbit indefinitely."
The process of retrieving Vanguard 1 could enhance the technical level of various "orbital services." Since Vanguard 1 is small, with a diameter of 15 cm and a weight of only 1.46 kg, it is especially suitable for advancing the technology of capturing and controlling satellites in orbit.
To recover Vanguard 1, both step one, which involves approaching and observing the satellite's status, and step two, which entails actually retrieving the satellite and bringing it back to Earth, are necessary. During this process, technologies such as space debris removal, in-orbit material retrieval, and re-thrust technology for deep-space exploration could be tested and practically applied.
◇ Development of a capture satellite to bring back Our Star 2
Researchers refer to Vanguard 1 as "a time capsule of the space age." Its significance is not merely historical.
Vanguard 1 is the first satellite to produce power using solar cells. Researchers expect that analyzing Vanguard 1, which has been in space for nearly 70 years, will provide significant information on how solar cells, batteries, and metals change in space.
Similar projects are underway in South Korea. The Korea Space Agency, Korea Aerospace Research Institute (KAI), and the Korea Advanced Institute of Science and Technology (KAIST) Satellite Research Institute are working on the active control of space objects. They are developing technology to approach satellites in space to change their position or orbit. The Korea Space Agency plans to launch an Arianespace 6 rocket by 2027, carrying a capture satellite to bring Our Star 2 back to Earth.
A Korea Space Agency official stated, "We plan to secure key technologies such as rendezvous and docking with satellites and robotic arms, and to develop a capture satellite applying these technologies. We will develop the next-generation small satellite 3 as capture satellite 1, and subsequently develop capture satellite 2, which can capture and remove multiple space objects, as well as a satellite for maintaining space systems."