What is the Karman Line?

As you all know, our planet Earth is just a tiny part of the vast universe, and there has to be some point where the Earth is separated from outer space. You also know, that Earth is not just the globe we see in pictures.

There is the atmosphere too which extends the boundary of the Earth further towards outer space. Here is where the term Karman Line comes in to play. The Karman Line is simply defined as the boundary between the Earth's atmosphere and outer space.

Although we say that this is the boundary of the Earth's atmosphere, there is no such exact line where, from that point onwards, the atmosphere exists no more.

What is happening here is that once you start going away from the Earth's surface, the atmosphere become thinner due to the lack of gravity and ultimately thins out to zero.

The important thing about the Karman Line is that it does not define this point where the atmosphere vanishes.

Instead what it defines is a plane, which is about 100 kilometres high from the Earth's surface. Other layers in the atmosphere such as the Thermosphere lies above 100 kilometres. The Karman Line actually defines the height where aeronautical activities cannot be carried out due to the thinness of the atmosphere.

The line has been named after Theodore von K rm n, a Hungarian-American engineer and physicist who was active primarily in the fields of aeronautics. He had first calculated in the 1950s, that around this altitude the Earth's atmosphere becomes too thin for aeronautic purposes.

Karman had calculated that above an altitude of roughly 100 kilometers (62miles), a vehicle would have to fly faster than orbital velocity (speed) in order to gain enough aerodynamic lift from the atmosphere to support itself.

For your information, the orbital speed of something is the speed at which it orbits around another larger body, while being under the balance of gravitational forces between each other. Though the calculated altitude was not exactly 100 km, Karman proposed that 100 km be the designated (picked out) boundary to space as the round number is easier to remember.

However, defining (showing clearly) the true boundary of the Earth's atmosphere is quite a challenge since the atmosphere's density (mass per unit of volume) varies, depending on the time of day, time of year, and recent solar flux (constant succession of changes).

***

Top space stories

First South Korean rocket launch:

The space exploration monopoly (exclusive right) which was maintained by Russia and United States is long gone now. Many other countries such as France, Japan, China and India have joined the space race. The latest competitor in this race is South Korea.

Having close ties with the Russian Space programme, South Korea is looking at launching its first rocket out in to space in 2008.

The first launch of this South Korean rocket is scheduled to take place from the Naro space centre, which is situated 450 km south of Seoul. This launch uses the South Korean Launch Vehicle KSLV. Apart from this, Russian and South Korean space companies are also developing another Korean launch vehicle.

In addition, the two countries are also involved in manned space flight cooperation. A contract was signed in December 2006 for a Korean astronaut to fly to the International Space Station (ISS) next spring.

South Korea has held a national competition to select the first Korean astronaut. Several possible candidates are presently training at the Gagarin centre in Russia under a separate contract.

***

China on a fast journey in the space race

China, who is a new entrant in the space race, has made rapid progress over the years, and right now it has taken the lead in the recent lunar explorations by sending the Change 1 satellite on a Long March 3A rocket on October 4, 2007 while Russia and the United State were still planning their new missions.

Experts say that this silent, yet specific approach taken by China is similar to the strategies used in oriental martial arts. The Chinese satellite is expected to have a life span of one year, and it will be mapping then Moon's surface during its lifelime.

The satellite launched on October 4 is expected to enter the orbit of the Moon on November 5.

Apart from this, from 2012, a Chinese lunar rover is scheduled to start functioning on the Moon. The next steps will be to bring samples of lunar soil back to Earth, mount a manned expedition and eventually establish a base, which is the general pattern followed by other countries.

China became only the third country to make independent manned space flights in October 2003 and October 2005. Over the past five years it has successfully launched 24 Changzheng rockets and developed and put into orbit 22 satellites of various types.

While successfully pursuing its own programme for the exploration of deep space, China also coordinates steps with Russia.

Aravinda Dassanyake