Definition of the edge of space
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Defining the Edge of Space: The Kármán Line and Alternative Boundaries
The "edge of space" is most commonly defined as the boundary where Earth's atmosphere ends and outer space begins. Traditionally, the Kármán line at 100 kilometers above sea level has been used as this demarcation. However, recent research suggests that this boundary may be more accurately placed at 80 kilometers, based on historical, physical, and technological considerations. This lower boundary better reflects the realities of orbital and suborbital trajectories used by space vehicles, and may be a more appropriate definition for the inner edge of outer space .
Historical and Physical Perspectives on the Edge of Space
The concept of the edge of space has evolved over time, influenced by advances in aerospace technology and our understanding of atmospheric physics. The original 100 km Kármán line was chosen because, at this altitude, the atmosphere becomes too thin to support conventional aircraft flight, and vehicles must achieve orbital velocity to remain aloft. However, analysis of actual vehicle trajectories and atmospheric properties indicates that significant changes in flight dynamics and atmospheric density occur closer to 80 km, supporting the argument for redefining the boundary .
Technological Implications of the Space Boundary
The definition of the edge of space has practical implications for aerospace engineering, legal frameworks, and international agreements. The chosen boundary affects how we classify space vehicles, determine airspace sovereignty, and regulate activities such as satellite launches and suborbital tourism. A more accurate boundary at 80 km could help clarify these distinctions and better align with current technological capabilities .
Broader Interpretations of "Edge" in Space and Geography
While the edge of space is a specific scientific and legal concept, the idea of "edges" or boundaries is also explored in other contexts, such as geography and computing. In geography, edges are seen as dynamic constructs shaped by institutional frameworks and societal factors, rather than fixed, predetermined lines . In computing, the term "edge" is used to describe decentralized processing near the source of data, and there is ongoing debate about how these concepts apply to space-based systems 36. However, these broader interpretations are distinct from the physical and legal definition of the edge of space.
Conclusion
The edge of space is most commonly defined by the Kármán line at 100 km, but recent research supports a boundary at 80 km as a more accurate and practical definition. This boundary marks the transition from Earth's atmosphere to outer space, with significant implications for technology, law, and policy. While the concept of "edges" is also important in other fields, the scientific definition of the edge of space remains a critical reference point for aerospace activities and international agreements 1236.
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