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Editorials/Opinions Analyses for UPSC – 13 July 2021


  1. Space tourism race and suborbital flight explained

Space tourism race and suborbital flight explained


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’.


GS-I: Geography (Physical Geography), GS-III: Science and Technology

Dimensions of the Article:

  1. Layers of the atmosphere
  1. Boundary of Space in light of recent “Space Flight”
  2. What are “suborbital” flights?
  3. Can the people on these “space flights” be called astronauts?

Layers of the atmosphere

  • The atmosphere consists of different layers with varying density and temperature. Density is highest near the surface of the earth and decreases with increasing altitude.
  • The column of atmosphere is divided into five different layers depending upon the temperature condition. They are: troposphere, stratosphere, mesosphere, thermosphere and exosphere.


  • The troposphere is the lowermost layer of the atmosphere. Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator.
  • Thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents.
  • This layer contains dust particles and water vapour. All changes in climate and weather take place in this layer.
  • The temperature in this layer decreases at the rate of 1° C for every 165m of height.
  • This is the most important layer for all biological activity.


  • The zone separating the tropsophere from stratosphere is known as the tropopause.
  • The air temperature at the tropopause is about minus 800C over the equator and about minus 45° C over the poles.
  • The temperature here is nearly constant, and hence, it is called the tropopause.
  • The stratosphere is found above the tropopause and extends up to a height of 50 km.
  • One important feature of the stratosphere is that it contains the ozone layer. This layer absorbs ultra-violet radiation and shields life on the earth from intense, harmful form of energy.


  • The mesosphere lies above the stratosphere, which extends up to a height of 80 km.
  • In this layer, once again, temperature starts decreasing with the increase in altitude and reaches up to minus 100° C at the height of 80 km.
  • The upper limit of mesosphere is known as the mesopause.


  • The ionosphere is located between 80 and 400 km above the mesopause.
  • It contains electrically charged particles known as ions, and hence, it is known as ionosphere.
  • Radio waves transmitted from the earth are reflected back to the earth by this layer.
  • Temperature here starts increasing with height.


  • The uppermost layer of the atmosphere above the thermosphere is known as the exosphere.
  • This is the highest layer but very little is known about it.
  • Whatever contents are there, these are extremely rarefied in this layer, and it gradually merges with the outer space.
  • Although all layers of the atmosphere must be exercising influence on us, geographers are concerned with the first two layers of the atmosphere.

Boundary of Space in light of recent “Space Flight”

  • 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.
  • The Kármán line has been compared to international waters, as there are no national boundaries and human laws in force beyond the line.
  • 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.
  • A research paper published in 2018 noted that the Kármán line “boundary was chosen as a nice round figure”, and it needs more studies from “a physical point of view” – and proposed that 80 km was a more appropriate boundary.
  • The chemical composition of the atmosphere is largely constant up to the mesopause, or the boundary between the mesosphere and the thermosphere. From a physical point of view, it is therefore reasonable to think of the atmosphere proper as including the troposphere and stratosphere and (with some qualification) the mesosphere, and identifying the thermosphere and exosphere with the common idea of ‘outer space’ according to a research paper.
  • Branson’s Virgin Galactic flight reached a height of 86km while Jeff Bezos’ Blue Origin flight is expected to go about 106km high.

What are “suborbital” flights?

  • If a spacecraft – or anything else, for that matter – reaches a speed of 17,500 mph (28,000 km/h) or more, instead of falling back to the ground, it will continuously fall around the Earth. That continuous falling is what it means to be in orbit and is how satellites and the Moon stay above Earth.
  • Anything that launches to space but does not have sufficient horizontal velocity to stay in space – like these rockets – comes back to Earth and therefore flies a suborbital trajectory.
  • In simple words, suborbital flights means that while these vehicles will cross the ill-defined boundary of space, they will not be going fast enough to stay in space once they get there.

Significance of suborbital flights

  • The accomplishment of reaching space in private spacecraft is a major milestone in the history of humanity.
  • Those aboard these and all future private-sector, suborbital flights will for a few minutes be in space, experience a few minutes of exhilarating weightlessness and absolutely earn their astronaut wings.

Can the people on these “space flights” be called astronauts?

  • a former commander of the International Space Station said there’s a big difference between riding along on a five-minute suborbital flight and performing a six-month orbital mission, but when it comes down to it, folks on both types of trips have earned the “astronaut” title.
  • A NASA astronaut said that there is an important distinction between being selected as a NASA astronaut and being a paying customer, but he was completely on board with space tourists earning the title of “astronaut”.

-Source: Indian Express

December 2023