The Indian spacecraft touched down on the Moon just a month ago, but it has already made significant contributions to science.
Following the successful Chandrayaan-3 Moon exploration mission, Indian scientists are continuing to analyze the data sent back to Earth by the Vikram lander and the Pragyan rover after a day on the Moon (equivalent to 14 Earth days) of diligent work.
Chandrayaan-3 is providing scientists with valuable new data and further inspiration for lunar exploration. The Indian Space Research Organisation (ISRO) is continuously sharing these initial findings with the world.
One notable achievement of the Pragyan rover is the detection of elements such as iron, titanium, aluminum, calcium, and especially sulfur (along with its varying concentrations) in the lunar soil.
The Vikram lander and Pragyan rover of the Chandrayaan-3 mission. (Photo: ISRO).
Previously, planetary scientists knew that sulfur existed in the rocks and soil of the Moon, but only at very low concentrations. New measurements from the Indian spacecraft suggest that there may be higher concentrations of sulfur in the lunar soil than previously predicted.
The Pragyan rover is equipped with two devices to analyze the elemental composition of the soil – including the Alpha Particle X-ray Spectrometer (APXS) and the Laser-Induced Breakdown Spectroscopy (LIBS). Both instruments were used to measure the sulfur concentration in the soil near the Shiv Shakti Point – the landing area of the Vikram lander from the Chandrayaan-3 mission.
Sulfur in the soil near the Moon’s poles could assist astronauts in surviving off Earth in the future. This is why astronomers view this discovery by the Indian spacecraft as a prime example of new-age lunar exploration.
Sulfur in Lunar Soil
Scientists have stated that there are two main types of rocks on the lunar surface – dark volcanic rocks and light-colored highland rocks. The brightness difference between these two rock types creates the familiar “Man in the Moon” image when viewed with the naked eye.
When scientists measured the composition of lunar soil and rocks in laboratories on Earth, they found that material from the dark volcanic plains tends to contain more sulfur than material from the brighter highlands.
The brightness difference between these two rock types creates the familiar “Man in the Moon” image when viewed with the naked eye. (Photo: Internet).
Explaining this, researchers noted: “Sulfur primarily comes from volcanic activity. The type of rock deep beneath the lunar surface contains sulfur, and when these rocks melt, sulfur becomes part of the magma. When the rock melts near the surface, most of the sulfur in the magma becomes gas released along with water vapor and carbon dioxide (CO2).”
Some sulfur exists in magma and is retained in the rocks after cooling. This process explains why most sulfur is associated with dark volcanic rocks on the Moon.
On-site sulfur measurements in the lunar soil from the Pragyan rover of Chandrayaan-3 mark the first time this has been done on the Moon. Initial data suggests the opposite.
Uncalibrated data collected by Pragyan’s LIBS instrument indicates that the lunar highland soil (near the poles) may contain higher sulfur concentrations than the equatorial highland soil, and may even exceed that of the dark volcanic soil.
Scientists note that to accurately determine the sulfur concentration in the lunar soil, a process called data calibration from ISRO must still be conducted.
However, these initial results provide lunar scientists with new insights into how the Moon functions as a geological system.
Formation of Sulfur in the Atmosphere
The measurement of sulfur concentrations is of interest to scientists for at least two reasons.
First, these findings suggest that the highland soil at the lunar poles may have fundamentally different compositions compared to the highland soil at the lunar equator. This compositional difference could stem from the different environmental conditions between the two areas – the poles receive less direct sunlight than the equatorial region.
Second, these initial results indicate that somehow the lunar soil at the polar regions contains more sulfur. The sulfur concentrated here may form from the Moon’s extremely thin atmosphere.
The lunar poles receive less direct sunlight, resulting in extremely low temperatures compared to the rest of the Moon. If surface temperatures drop below -73 degrees Celsius, sulfur from the lunar atmosphere could accumulate on the surface in solid form – similar to frost on a window.
Sulfur at the poles may also originate from ancient volcanic eruptions on the Moon’s surface or from sulfur-rich meteoroids striking the surface and vaporizing upon impact.
Lunar Sulfur as a Valuable Resource
For long-duration space missions, many space agencies have considered establishing bases on the Moon.
Astronauts and robots could move from a southern polar base to collect, process, store, and utilize naturally occurring materials like sulfur on the Moon – a concept known as in-situ resource utilization.
In-situ resource utilization means that humanity would not have to return to Earth multiple times for supplies, allowing more time and energy to be spent on deeper lunar exploration.
By utilizing sulfur as a resource, astronauts could manufacture solar panels and sulfur batteries, mix sulfur-based fertilizers, and create sulfur-based concrete for construction.
The on-site measurements from the Pragyan rover have contributed to scientists visualizing the characteristics of lunar soil. (Photo: Indy 100).
Sulfur-based concrete actually has several advantages over conventional concrete, which is used in construction projects on Earth. Scientists explain:
First, sulfur-based concrete sets and hardens within a few hours instead of several weeks and has a higher resistance to wear.
Second, sulfur does not require water in the mixture, allowing astronauts to conserve their precious water supplies for drinking, producing breathable oxygen, and generating rocket fuel.
For a long time, the search for Helium-3 on the Moon has been one of the primary reasons why many space powers are racing to the Moon. Helium-3 is considered a clean fuel for next-generation reactors on Earth. However, it seems that the discovery of sulfur on the Moon may be even more beneficial for humanity as we aim to harness in-situ resource utilization.
As of now, there are seven missions operating on or around the Moon, but the lunar south pole has not been extensively explored. Therefore, the new on-site measurements from the Pragyan rover have contributed to scientists visualizing the characteristics of lunar soil and opened up hopes for a future settlement on this natural satellite of Earth.
Currently, scientists at the Indian Space Research Organisation (ISRO) are busy processing and calibrating the data.
On the lunar surface, the duo of Vikram and Pragyan from the Chandrayaan-3 mission remain deep in slumber after a frigid Moon night. ISRO is still working to re-establish communication with the two spacecraft until the next lunar night descends on October 6.
There is no guarantee that the two Chandrayaan-3 spacecraft will survive the extreme low temperatures, but if Pragyan awakens, Indian scientists can look forward to even more valuable measurements.
