Where is Space?

Have you ever wondered where space begins? You’re not alone.

To help answer “where is space?” I spoke with Andrew Rush, Space Lawyer and author of IPinSpace.com. The results may surprise you. Turns out, nobody can really agree on where it starts and that was before governments got involved.

Seriously…Where is Space?

Ask any four year old “Where is space?” and they will likely reply “Up there!” If you look to the Outer Space Treaty or virtually any other law for an international definition of where space begins, you’re not going to do much better than the four year old’s answer.

We have long recognized that all countries have the right to control their airspace, but somewhere above those nations airspace ends and outer space begins! International law says outer space “shall be free for exploration and use by all.” This creates a legal tension- Where, exactly, does national control over “up there” stop? Where do we begin applying space law?

Karmen Line

Efforts to define where space begins take three different approaches.The first approach is physical: Earth ends and space begins somewhere, right? The most popular physical boundary is the Karman Line, defining the beginning of space as 100 km above sea level. This is the average altitude where the atmosphere is so thin that, in theory, an airplane would have to travel faster than orbital velocity in order to generate enough lift to fly. But earth’s atmosphere doesn’t actually end at this point! Hundreds of satellites in low earth orbit are still affected by atmospheric drag.

Functional Approach

The second approach is functional, finding its roots in the law of the sea. This approach focuses on the purpose and design of the spacecraft and whether it has been placed into service. For reusable spacecraft, this approach gives more control over when space law is applied because, much like maritime shakedown cruises, test flights might be performed before the vehicle is placed into service. On the other hand, a functional approach might lead to space law attaching to a reusable vehicle even when it is planted firmly on Earth.

Definition by Fiat

Definition by fiat has been applied as far back as 1976 when equatorial nations attempted to assert their sovereignty over outer space by declaring that geosynchronous orbits are subject to national control. If widely adopted, this definition by fiat could mean that space doesn’t begin until some point beyond 38,000 km above sea level.

Of the three approaches to defining where space begins, the physical Karman Line is the most widely accepted by the popular press while Australian law has adopted the definition by fiat approach. Despite these efforts and long standing international treaties governing spacecraft, where space begins remains hazy.

Your Turn

Where do you think Space begins? Let me know in the comments below.

Thanks for watching.