# Redefining the Boundary of Space: The 80 km Debate

February 3, 2024## The Karman Line Controversy: A New Edge of Space

Exploring the edge of space, this article delves into the debate over the conventional 100-km Karman line, proposing a reevaluation to 80 km based on modern understanding of atmospheric science and orbital dynamics. It invites a rethinking of how we define the boundary between Earth's atmosphere and outer space.

**Read the full story here:** Where Does Outer Space Begin?

**Highlights**

- The 100-km Karman line is widely accepted but not rigorously defined.
- Atmospheric density and pressure decrease with altitude, affecting lift and defining space's edge.
- Theodore von Kármán's calculations suggest an 84-km limit based on aircraft lift capabilities.
- Satellite orbit studies propose a lower demarcation line for space at 80 km.
- Legal and operational implications exist for defining airspace and outer space boundaries.
- Science often deals with fuzzy borders, necessitating context-dependent definitions.

The article opens by questioning the established 100-km altitude, known as the Karman line, as the boundary of outer space. It discusses the difficulty in defining 'space' due to the gradual thinning of the atmosphere and introduces the notion that a lower altitude, such as 80 km, might be more appropriate based on atmospheric and orbital mechanics.

The piece delves into the history and calculations behind the Karman line, including Theodore von Kármán's work and the suggestion by Robert Jastrow for a 160-km boundary. It highlights the role of gravity and pressure in containing Earth's atmosphere and the impact of altitude on air density and lift, which are crucial for flight and the definition of space.

Finally, the article explores the practical implications of redefining the boundary of space, including legal, operational, and recognition aspects of space travel. It suggests that a standardized definition may not be feasible due to the nature of science and the need for context-dependent definitions, echoing Jonathan McDowell's research and proposals for an 80-km limit.

Read the full article here.

**Essential Insights**

**Phil Plait**: Author of the article discussing the altitude at which outer space begins.**Theodore von Kármán**: Hungarian polymath who calculated the altitude where an aircraft's lift becomes ineffective, leading to the definition of the Karman line.**Robert Jastrow**: Astronomer who suggested 160 km as the transition line between Earth and space.**Jonathan McDowell**: Astrophysicist and space historian who argues for an 80 km demarcation line for outer space.**World Air Sports Federation**: Organization that has adopted the 100-km limit as the edge of space for certifying records in aeronautic and astronautic travel.

**Tags:**Space Boundary, Karman Line, Atmospheric Science, Outer Space Definition, Aerospace Engineering, Astrophysics, Space Law, Orbital Mechanics