ISRO had five science payloads developed by it on the satellite. One of them, called Hyper Spectral Imager (HySI), is designed to collect spectroscopic data on the mineral composition of the lunar surface. In addition, the imager will get data on the deep crater regions as well as central peaks, which would reveal the mineral composition of the Moon’s interior.
The imager can map the surface in 32 contiguous bands in the Very Near Infrared spectral range (0.4-0.95 mm). It can distinguish the spectral bands at a 15 nm resolution. The spatial resolution is 80 m with a swath of 20 km. the imager will collect the Sun’s reflected light from the Moon’s surface. The image is acquired in a push broom mode as the satellite moves along.
The second payload, the Terrain Mapping Camera (TMC), will map the topography in both near and far side of the Moon and prepare a three-dimensional atlas with high spectral and altitude resolution. The mapping camera has view angle of plus or minus 25 degrees and it will measure the solar radiation reflected or scattered from the lunar surface. The camera will have four settings to cover the varying illumination conditions over the Moon. Care is taken to capture the poor illumination in the polar region all the time.
The lunar gravity field needs an improved model.The third payload comprising of the Lunar Laser Ranging Instrument (LLRI) on board the satellite will supplement the data from the terrain mapping camera. The laser ranging probe will help in studying the morphology of large basins and other lunar features as well as provide the density distribution of the crust.
A coherent pulse of light (at 1064 nm wavelength) is transmitted to the lunar surface. Some of the light is scattered back and optical receivers collect it and focus it on to a photo electronic detector. The payload will help in determining the global topographical field of the Moon.
The fourth payload, High-Energy X-ray Spectrometer (HEX), is the first experiment designed to carry out spectral studies of planetary surface at hard X-ray energies (in the region of 30 KeV to 250 KeV). The experiment will study the emission due to radioactive decay of uranium-238 and thorium-232 on the lunar surface. Various lunar terrains, including polar regions, will be studied and their chemical composition described on the basis of their radioactivity.
The fifth-payload Moon Impact Probe (MIP) is designed to impact at a pre-selected location, after the orbiter reaches the final 100 km orbit. The probe will qualify technologies required for future soft landing missions, while demonstrating the technique of predetermined impact of a probe on the lunar surface. Its operation was a success.
The payload weighs 29 kg, will have a radar altimeter for measuring the altitudes of the probe above the surface and qualify the technologies for future landing missions; a video imaging system and a mass spectrometer for measuring the constituents of tenuous lunar atmosphere during descent.
Chandrayaan-1 Carries Six Foreign Payloads. All of them together weight 24 kg.
One of them, an Imaging X-ray Spectrometer (C1XS), has been added through the European Space Agency (ESA) in collaboration with Rutherford Appleton Laboratory (UK) and ISRO Satellite Centre.
The probe is based on the fact that the Sun provides a natural source of X-rays and strikes the lunar surface. Each element produces X-rays with a unique set of energies. It is thus possible to carry out high-quality X-ray spectroscopic mapping of the Moon. The technique is called X-ray Fluorescence and is used for measuring elemental abundance distribution over the lunar surface. The probe can detect calcium and some other elements during solar flares in addition to normal findings of elements.
By coincidence, the probe will observe the Moon during the rising phase of the solar cycle, when X-ray signals would be considerably stronger. The probe would reach lunar orbit in a short time; thereby it would suffer the least radiation damage en route (it has a deploy-able shield for use during the passage through the Earth’s radiation belts). Moreover the probe would observe the Moon from a close circular (100 km) polar orbit. And the instrument is based on the successful device carried by ESA’s Smart mission, which has clearly detected calcium on the Moon.
The Max Plank Institute for Solar System Science (and ESA) has designed a Near-Infrared Spectrometer (SIR-2) for studying the lunar surface in six broad categories; detailed analysis of lunar surface in various geological, mineralogical and topographical units; study of the vertical distribution of the crustal material; investigating the process of basin, maria and crater formation; study of the impact of space ‘weather’ on the lunar surface and survey of mineral resources for future exploration and landing sites. Near-infrared measurements are expected to reveal absorption bands typical of various minerals and ice. The XSM (X-ray Solar Monitor) collects the Sun’s light reflected by the Moon and disperses it to reach a detector of different wavelengths. The range of the spectrometer is 0.93-2.4 mm (with a spectral resolution of 6nm)
The Swedish Institute of Space Physics has developed a unique payload called Energetic Neutral Analyzer(CENA) to image the Moon’s surface, using low energy neutral atoms. The objectives are: imaging the surface composition including the permanently shadowed areas, imaging the interaction of the solar wind and the Moon, and imaging the lunar surface magnetic anomalies. As there is no magnetosphere or atmosphere on the Moon, the solar wind directly impacts its surface. The particles leave the surface mostly as neutral atoms. An imaging mass spectrometer—first of its kind for planetary exploration—will detect such atoms to meet the scientific objectives. ISRO has designed and developed the data processing unit of the payload, which weights 3.5 kg.
The Earth’s magnetic field deflects the solar wind along with helium-3, which thus becomes a rare isotope on Earth. But the Moon captures helium-3 and its top soil should reveal it. Helium is useful in fusion reactors and the Moon may well become a source of limitless cheap energy.
An American payload seeks to probe the scope for water on the Moon. Lunar samples brought back by astronauts from the Moon show the Moon as an exceedingly dry place. But recent discoveries suggest that water-ice may exist in the polar regions. The poles of the Moon have permanently dark areas, because of the Moon’s axis of rotation. There are the so-called cold traps (50 to 70 K) that have never seen the Sun. As water-bearing minerals in meteorites or cometary debris constantly bombard the Moon, and even granting that most of the water might have been lost to space, water molecules in the cold trap could accumulate over geological time.
The payload from Applied Physics Laboratory of the Johns Hopkins University and Naval Air Warfare Centre (US) through NASA is called Miniature Synthetic Aperture Radar (MiniSAR). The mapper (6.5 kg) will view all permanently shadowed areas on the Moon, so that ice and dry lunar surface are clearly distinguished.
Another American payload (7 kg) is called Moon Mineralogy Mapper (M3). The primary goal is to characterize and map lunar surface mineralogy in the context of lunar geologic evolution. Mineral resources will be assessed at high spatial resolution to support future missions. Towards this end, the payload seeks to accurately measure the absorption features of rocks and minerals and study the active processes on the Moon. The payload is from Brown University and Jet Propulsion Laboratory through NASA. The scientific instrument measure solar reflected energy and each pixel would correspond to 70 m from an orbit of 100 km with a 40-km field of view.
The Bulgarian Academy of Sciences has designed a unique payload to study the Radiation hazards during lunar explorations that would be useful for future manned Moon missions called Solar Wind Monitor (SWIM). It is known that outside the Earth’s magnetosphere, galactic cosmic rays are somewhat modulated by the solar wind (low energy charged particles that constantly blow from the Sun). Solar energetic particles emitted during solar flares (sudden eruptions from the Sun’s chromosphere) pose a radiation hazard. Ionizing radiation is a major limitation on future manned space missions.
The payload is a miniature spectrometer-dosimeter. Its detector weights less than one gram (0.1398 gm)! Called RADOM-7, the scientific instrument will evaluate the shielding characteristics, if any, of the Moon’s environment against galactic and solar cosmic radiation and solar particle events.