Rediscovered After 25 Years: US Satellite Lost and Found in Space
Key Takeaway
A small satellite called S73-7, launched in 1974 as part of a US Air Force mission, has been rediscovered after nearly 25 years of being untracked, thanks to the efforts of the 18th Space Defense Squadron.
Summary
- S73-7, also known as the Infra-Red Calibration Balloon, was a 26-inch wide satellite launched in 1974 as a payload aboard the larger KH-9 Hexagon System satellite.
- It was meant to inflate a balloon and continuously orbit the Earth at an altitude of 500 miles (805 km) to aid in the calibration of ground-based remote sensing equipment.
- However, the satellite’s deployment failed, and it has periodically disappeared from radar tracking since the 1970s.
- It went missing twice, first in the 1970s and then again in the 1990s, raising questions about how it could seemingly vanish from radar for so long.
- Tracking satellites in low-Earth orbit can be challenging, especially if they do not transmit their identities and orbit near the equator, creating blind spots for radar systems.
- After being untracked for nearly 25 years, S73-7 has been rediscovered and is currently being tracked again by the 18th Space Defense Squadron.
- The rediscovery was announced on X (formerly Twitter) by astrophysicist Jonathan McDowell, who shared a graphic showing the satellite’s known locations since 1975.
- The graphic reveals that S73-7 has been gradually losing altitude, dropping from its initial height of about 500 miles (805 km) to around 491 miles (790 km) today.
- The satellite’s reappearance after such a long period highlights the challenges of tracking and monitoring the vast number of objects in Earth’s orbit, especially those that do not actively transmit their identities or locations.
The Rediscovery of a Lost Satellite
Launched in 1974 as part of a United States Air Force mission, the satellite known as S73-7, or the Infra-Red Calibration Balloon, was designed to inflate a balloon and continuously orbit the Earth at an altitude of approximately 500 miles (805 km). Its purpose was to aid in the calibration of ground-based remote sensing equipment, a crucial task for ensuring accurate data collection from space.
However, the satellite’s deployment did not go as planned, and it has periodically disappeared from radar tracking since the 1970s. This elusive behavior led to S73-7 being considered lost twice, first in the 1970s and then again in the 1990s, raising questions about how such an object could seemingly vanish from our tracking systems for extended periods.
After nearly 25 years of being untracked, S73-7 has now been rediscovered, thanks to the efforts of the 18th Space Defense Squadron. The rediscovery was announced on X (formerly Twitter) by astrophysicist Jonathan McDowell, who shared a graphic showing the satellite’s known locations since 1975.
The rediscovery of S73-7 highlights the significant challenges involved in tracking and monitoring the vast number of objects orbiting our planet. With over 20,000 cataloged pieces of debris, ranging from spent rocket stages to defunct satellites, the task of maintaining situational awareness in space is a daunting one.
One of the primary challenges is the fact that many of these objects do not actively transmit their identities or locations. This makes it difficult for ground-based radar systems to accurately track and identify them, especially when they orbit near the equator, creating blind spots for traditional tracking methods.
Additionally, the sheer number of objects in Earth’s orbit, coupled with their constant motion and potential for unexpected maneuvers, further complicates the tracking process. It’s akin to finding a needle in an intergalactic haystack, as Jonathan McDowell rightly described.
The rediscovery of S73-7 serves as a reminder of the critical importance of maintaining robust space situational awareness. As our reliance on space-based assets continues to grow, from communication satellites to weather monitoring systems, the need to accurately track and catalog debris becomes increasingly crucial.
Untracked debris poses a significant threat to operational spacecraft, as even a small piece of debris traveling at high speeds can cause catastrophic damage. This risk underscores the need for improved tracking mechanisms and international cooperation to ensure the sustainable use of the space domain.
Furthermore, the ability to track and monitor space debris is not just about mitigating immediate risks; it also plays a vital role in enabling future space exploration and utilization. As we look towards ambitious goals such as establishing a sustained human presence on the Moon and eventually exploring Mars, a comprehensive understanding of the space environment and the ability to navigate through it safely will be paramount.
Addressing the challenges of space debris tracking and maintaining situational awareness in space will require a multifaceted approach involving technological advancements, international collaboration, and a commitment to responsible space stewardship.
One potential solution lies in the development of advanced tracking systems that can more accurately detect and identify objects, even those that do not actively transmit signals. This could involve the use of advanced radar systems, optical telescopes, and even space-based sensors to provide a more comprehensive picture of the space environment.
Additionally, international cooperation and data sharing among space agencies and private entities will be crucial in creating a unified, global space situational awareness network. By pooling resources and sharing information, we can improve our collective understanding of the space domain and better coordinate efforts to mitigate risks.
Finally, a renewed emphasis on responsible space stewardship is essential. This includes implementing measures to minimize the creation of new debris, such as designing spacecraft with end-of-life disposal plans and adhering to best practices for mitigating the risk of collisions.
The rediscovery of S73-7 serves as a touching reminder of the challenges we face in maintaining situational awareness in the increasingly congested space domain. While the satellite’s reappearance is a testament to the dedication and perseverance of those involved in space debris tracking, it also highlights the pressing need for enhanced tracking mechanisms and a concerted effort to address the growing issue of space debris.
As we continue to explore and utilize the vast expanse of space, it is imperative that we prioritize the development of robust tracking systems, foster international collaboration, and promote responsible space stewardship. Only by addressing these challenges head-on can we ensure the sustainable and safe use of the space domain for generations to come.