In the universe we inhabit, Helium comes second after Hydrogen. Hydrogen has almost 88 per cent share of all atoms in the Universe. About 11.3 per cent atoms are composed of Helium. Helium was first detected in the Sun. No doubt the Sun is by far the greatest source of Helium known to man.
In the Sun every second about 700 million tonnes of Hydrogen gets converted into 695 million tonnes of Helium and 5 million tonnes is converted into energy in the form of light and heat. A balance is maintained in the ratio of Hydrogen and Helium in the core. The core is made up of as much as 71 per cent Hydrogen and 27 per cent Helium.
The Moon is Earth’s natural satellite and could also be a future destination for man. Among the astronomical bodies, moon is most accessible. Moon explorations through space rockets began several decades ago. First manned Space flight with Yuri Gagarin from Soviet Union on board took place in 1961. Neil Armstrong in Apollo-ll mission became the first person to land on moon on 20 July 1969.
We have come a long way since then to understand topography and composition of Moon. Helium became indispensable for space programmes and Lunar launch vehicles. Moon missions like Lunar Crater Observation and Sensing Satellite (LCROSS) has been the part of the study of cool grain chemistry of the Moon surface. From these observations presence of several light metals, like sodium and mercury, gases like methane, ammonia and carbon dioxide, carbon monoxide and hydrogen, some water and also heavier rare Earth metals have been detected on the moon surface. Helium is the latest addition to this list.
India launched its first satellite to moon named ‘Chandrayaan’ in 2008. Among its payloads it carried instruments like Hyper Spectral Imaging Cameras and Moon Mineralogy Mapper (M3) for imaging the moon basins and data collection. The Imaging camera was designed to collect spectroscopic data of mineral composition on the surface and interior. M3 did wonderful job of mapping the moon surface and analyzing its content. Mineral samples collected from moon have shown higher presence of He-3 isotope as compared to He-4.
On Earth, the Helium in the Natural gas resources mainly comprises the isotope He-4. But Moon has different soil properties and there is no atmosphere like Earth. It is established that winds coming fro Sun called ‘solar winds’ carry streams of hot gases and negatively or positively charged particles. Solar winds are continuously flowing outwards from the Sun and get deposited on the moon surface. Presence of He-3, which is a by-product of fusion reaction in Sun, has been detected in these particles.
Moon is therefore having good amount of Helium isotope He-3, which is a fuel for nuclear fusion reactor. The ratio R on moon is about 100 RA. To deal with energy and climate change concerns from greenhouse gas emissions, every nation wished to be part of nuclear fusion energy production programme.
High ratio of He-3 and He-4 makes moon very precious for meeting our future fuel needs in a fusion reactor. Countries like USA, Japan, European Union as well as China and India are having vision and mission to build future lunar colonies. It is expected that manned lunar bases may come up post 2028.
Other Planet in Our Solar System
In our galaxy, in the stars and planets of the solar system both Hydrogen and Helium are the main constituents. Both Jupiter and Saturn are Giant gaseous planets, with almost one hundred times the mass of the Earth. Helium content could be high in them. Both Jupiter and Saturn radiate more energy flows, which may throw some light on the origin of the solar system. Spacecraft launches have been made for exploration and testing the models of their evolution and structure to describe their luminosity.
Studies are being made to understand how Hydrogen and Helium mixture would have formed in the stars and the giant planets. Hydrogen is the main component as an insulating gas. But, it undergoes phase transition and is found to become metallic when subjected to very high pressure at high temperatures.
A Galileo Probe was sent to Jupiter from NASA to know about Jupiter. Significant dearth of Neon in its atmosphere was reported and Helium raining droplets inside the core were detected.
To explain these phenomena several hypotheses have been proposed. It is presumed that Helium droplets are formed in the outer atmosphere of Jupiter where inert gas Neon gets dissolved in to these droplets. Metallic Hydrogen is present in the fluid form and huge gravitational energy is released while passing through it. This results in Neon scarcity. As they become heavier the droplets fall towards the hot interior of the planet.
This unique hypothesis needs to be tested and proven. In August 2011, another spacecraft named JUNO has been sent to Jupiter. According to Greek mythology ‘Juno’ is the name of goddess wife of god Jupiter. Juno is expected to reach Jupiter in five years and make further studies. Hopefully, after completion of its journey Juno would reveal many new secrets about Jupiter, its origin, evolution, structure and the vital role of Helium in our Universe. Saturn is another Giant planet having high Helium content.
In addition to these, Uranus and Neptune are two smaller planets that could also have high He-3 content. It is said that they may be having more than ten thousand times more Helium than that of Moon. Further studies are needed to confirm this. We can say is that if Helium from astronomical bodies ca be brought to Earth, there would be no shortage of fuel energy, now and in the future.