Indian Space Research Organisation (Isro) has received a patent for its method of manufacturing highland lunar soil simulant. The simulant is made in bulk from similar rock samples identified and picked out from Sittampundi Anorthosite Complex, almost 67 km from Salem, in Tamil Nadu.
The procedure has satisfied all aspects such as mineralogy, bulk chemistry, grain size distribution and geo-mechanical properties. The method used for preparing the lunar simulant is cost-effective, reproducible and easy to scale up, said the patent specification filed by the Space Agency.
The simulant is quite similar to the regolith (loose unconsolidated rock and dust that sits atop a layer of bedrock according to Encyclopaedia Britannica) of lunar highland region. It can be used to control the mobility of the rover for scientific exploration and for the study of geo-technical or mechanical properties of lunar soil.
The simulant could also be used for fundamental theoretical and experimental research for constructing civil engineering structures on the surface of the Moon, and to make headway in lunar locomotive engineering.
There are bright and dark areas on the Moon's surface. The dark areas are called Maria or mare, which are mostly flat, while the highlands are heavily cratered and mountainous. Isro's patent application claims that most of the countries produced simulants representing lunar mare region, while the highland crust occupies 83 per cent of the lunar surface. Yet, only a limited number of simulants represent the regolith of this region.
It is difficult, expensive, and time-consuming to produce simulants in large numbers. Hence, there is a need for low-priced simulants for diverse lunar applications in order to minimise mission risk. The inventors have ingeniously arrived at a method to make a lunar simulant that has a chemical and mineralogical composition, and mechanical and geotechnical properties that are similar to those of lunar soil.
"Most future missions propose for soft landing on the lunar highland region. Hence there is an urgent need for bulk quantity of lunar soil simulants that represent the highland lunar crust," it said in the patent specification filed in 2014. Isro added that its simulant is exclusively manufactured to represent lunar highland region and should also be useable in diverse lunar applications to provide lowest possible risk.
It may be recalled that for Chandrayaan-2, India's first moon landing experiment, Isro had developed lander and rover indegenously after the Russian promise to offer the technology did not come up. These were tested in a simulated atmosphere with support of surface created by rocks transported from Salem. These rocks were similar in compositiom to the Moon's surface. Reports said the rocks were crushed to the required size and moved to Bengaluru where the facility was created. The mission, with an orbiter, a rover and a probe, successfully placed the orbiter which will have an extended lifespan of seven years, while the lander crashed on the Moon's south pole in September 2019.
Several countries have been developing and producing lunar simulants, including the US, Japan and China, and several attempts has been made in the past to reproduce the lunar environment for research purpose. There has been renewed interest by many of these countries in probing Earth's only natural satellite for its mineral content in the recent past.
Reports quoting Isro in 2019 said the space agency has plans to explore a joint satellite mission in Moon's polar region in collaboration with Japan Aerospace Exploration Agency (Jaxa).
According to reports, Isro has announced a Chandrayaan-3 mission similar in configuration to the second Moon mission. It said that Chandrayaan-2 was a highly complex mission, as it brought together an Orbiter, Lander and Rover to explore the Moon's south pole. This mission was unique in that it aimed at studying not just one area of the Moon but all areas combining the exosphere, the surface as well as the sub-surface of the satellite in a single mission.
"The Moon is the closest cosmic body at which space discovery can be attempted and documented. It is also a promising test bed to demonstrate technologies required for deep-space missions, said Isro in its Chandrayaan-2 mission page.
Chandrayaan-2 was aimed for enhancing our understanding of the Moon, stimulate the advancement of technology, promote
global alliances and inspire a future generation of explorers and scientists," .