Jonathan's Space Report and the Boundary of Space
Tracking the history of spaceflight requires a meticulous approach to data and a commitment to transparency. Since 1989, Jonathan McDowell has provided this service through Jonathan's Space Report, a free internet newsletter dedicated to documenting the technical specifics of satellite launches. By synthesizing information from original sources—including Russian-language publications and declassified Department of Defense documents—McDowell has created a vital resource for the space community, much of which is also available on his personal website.
Defining the Edge of Space
One of the most debated topics in aerospace is where the atmosphere ends and outer space begins. In 1994, while publishing a history of the North American X-15 spaceplane, McDowell proposed that 80 kilometres (50 mi) should be adopted as the official boundary of space. This altitude is situated within the mesosphere, the middle layer of Earth's atmosphere.
This proposal aligns with the standards used by the United States to grant astronaut status to pilots, a practice established during the X-15 program. However, this figure differs from the Kármán line, the internationally recognized boundary of 100 km used by the Fédération Aéronautique Internationale (FAI).
Scientific Arguments for the 80 km Boundary
The debate over the boundary of space is not merely semantic but based on physical properties. In 2018, McDowell expanded on his earlier suggestions by publishing a refereed journal paper in Acta Astronautica. In this publication, he presented detailed physical arguments to support the 80 km value as a more accurate representation of the transition to space.
| Standard/Entity | Altitude | Context/Usage |
|---|---|---|
| Jonathan McDowell / US Standard | 80 km (50 mi) | X-15 program and astronaut status |
| Kármán line (FAI) | 100 km | Internationally accepted boundary |
Key Facts
- Jonathan's Space Report has been documenting satellite launch technicalities since 1989.
- Data sources include declassified Department of Defense documents and Russian publications.
- McDowell advocates for a space boundary of 80 km (50 mi).
- The 80 km threshold is the altitude used by the US to confer astronaut status.
- The Fédération Aéronautique Internationale recognizes the Kármán line at 100 km.
- Physical arguments for the 80 km boundary were published in the journal Acta Astronautica in 2018.
Frequently Asked Questions
What is Jonathan's Space Report?
It is a free internet newsletter started in 1989 by Jonathan McDowell that documents the technical details of satellite launches using original and declassified sources.
What is the Kármán line?
The Kármán line is the internationally accepted boundary of space, set at an altitude of 100 km by the Fédération Aéronautique Internationale.
Why does Jonathan McDowell suggest 80 km as the space boundary?
McDowell bases this on the altitude used by the United States to grant astronaut status (as seen in the X-15 program) and provided detailed physical arguments for this value in a 2018 Acta Astronautica paper.
Where is the 80 km boundary located in the atmosphere?
The 80 km boundary is located within the mesosphere.
What sources are used for the technical data in the Space Report?
The report utilizes original sources, including Russian-language publications and declassified documents from the Department of Defense.