On July 11, British businessman Richard Branson beat rival Jeff Bezos to reach the edge of space, giving space tourism an official kickstart.

But experts and space enthusiasts are in doubt whether the height to which he travelled can be termed ‘space’.

Boundary of space:

The most widely accepted boundary of space is known as the Kármán line, 100km above mean sea level.

• But the United States uses 80km as the cutoff point.
• Branson’s Virgin Galactic flight reached a height of 86km while Jeff Bezos’ Blue Origin flight is expected to go about 106km high.

The Kármán line has been compared to international waters, as there are no national boundaries and human laws in force beyond the line.

Why do we need a Kármán line?

The 1967 Outer Space Treaty says that space should be accessible to all countries and can be freely and scientifically investigated.

• Defining a legal boundary of what and where space is can help avoid disputes and keep track of space activities and human space travel.
• Some countries, including the United States, believe that defining or delimiting outer space is not necessary.
• On the other hand, an expert on space law, told The Verge that now is the time to define what space truly is, because more and more commercial companies have plans to go to space.
• In the long-term, as we see more commercial operations in those altitudes, especially getting up into orbit and coming back, these private companies are going to want the legal certainty that would be provided by having a set altitude or limit.

Where is space?

• It has been tricky understanding where our atmosphere ends and what should be called space.
• In 2009, researchers from the University of Calgary measured the winds of Earth’s atmosphere and the flow of charged particles in space and wrote that the edge of space begins at 118km above sea level.

Layers of the atmosphere:

The Earth’s atmosphere has been divided into various layers:

1. The troposphere starting at the Earth’s surface and extending about 14.5 km high,
2. Stratosphere extending to 50 km,
3. Mesosphere to 85 km,
4. Thermosphere to 600 kilometers and
5. Exosphere to 10,000 km.

Experts have noted that the chemical composition of the atmosphere was largely constant up to the mesopause, or the boundary between the mesosphere and the thermosphere.

• From a physical point of view, the atmosphere includes the troposphere and stratosphere and (with some qualification) the mesosphere.
• Thermosphere and Exosphere are including with the common idea of ‘outer space’.

Source: Indian Express