GOING beyond Earth’s confines, we may come across many strange hurdles not in our reckoning as yet. Van Allen belt is one such barrier, notably to electronic equipment placed aboard the spacecraft. Let us take a probing look at it from a junior scientist’s perspective.

One of the least, and somewhat recently understood phenomenon in space sciences, and one of the most spectacular discoveries of the 1950s (besides the Big Bang) was the hitherto unsuspected belts of charged particles surrounding Earth at high altitudes called, Van Allen Radiation Belts.

These are at least two layers of energetically charged particles (plasma, or a gas that at very high temperatures has all the electrons stripped off its atoms) that surround Earth, and are held in place around the planet by its inexorable magnetic field. The belts extend from an altitude of about 1,000km to 60,000km above the surface of Earth. The radiation levels in this wide band of region vary, from somewhat low, to very high. Naturally, most of the particles, or energy forms that form the belt, come from solar wind, but a small, but significant portion, comes from cosmic rays travelling from far beyond.

The belts are named after their discoverer, James Van Allen (1914-2006). These are located in the inner region of Earth’s magnetosphere, that is, the area where Earth’s pervasive gravitational field extends.

Blowing outward from the Sun at 400 km/sec in all directions, the solar wind consists of iodised gases, carrying a small part of Sun’s magnetic field with them. It is deflected like water flowing around a boulder in a stream. Earth acts like a barrier to the free-flowing, highly charged particles. High energy particles from the solar wind leak into the magnetosphere and become trapped within Earth’s magnetic field to produce the Van Allen belt of radiation. All planets that have magnetic fields have them. Travelling unhindered at 400 km/sec, it would take over two hours to reach Earth, in approximately 140 minutes.

Naturally, having emanated from Sun, the solar wind is bound to carry a signature of its intrinsic or original strength. Also, distance does not slow them down. Following Newtonian laws of motion, solar wind continues to travel to infinity. Hence there are cosmic rays throughout the galaxy and beyond.

However, Van Allen Radiation Belts pose a hazard to all kinds of space satellites which must avoid ways to circumvent them in order to survive and carry on in their mission into deep space. The spacecraft must be equipped with protective shielding, especially if in the course of their orbits they are required to spend significant length of time in the radiation belts.

In 2013 Nasa reported that the Probes had discovered a transient third belt. But I believe that this one is truly temporary and sort of comes and goes.

For some time, the issues of eukaryotes and prokaryotes took our fancy in explaining the origin of life. The stunning fact is that for a total of one billion years these two virtually ruled the roost. Of the two, the first one reigned for 800 million years while prokaryotes, the double-cell creature rumbled on for 200 million years. They were the only world powers while it lasted.

It took life a pretty long time to develop from the double-cell prokaryotes into something more complex: the multi-cellular life forms. We are all multi-cellular. The smallest, simplest animal may consist of just a few thousand cells, that is, a tiny worm or a beetle. As for the bigger, more complex life forms, they may comprise trillions, or even thousands of trillions of cells, as you already know. We have to see the myriad life forms and wonder at them: how very different from one another, yet how similar!

It is wonderful to imagine how life grew into such complicated and complex forms so quickly — in a matter of one billion years! Think about it!

Meanwhile, Van Allen Radiation Belts continue to claim the attention of a large number of scientists dedicated to probe deeply. That they are held in place, and prevent a large segment of lethal solar wind consisting of very harmful ultra-violet and other equally (almost but not quite) dangerous forms of radiation from reaching the surface of the planet, and it’s atmosphere.