Chandrayan

Introduction to Chandrayaan-1:

Chandrayaan-1, India.s first scientific mission to Moon is slatedfor launch during 2007. The primary objectives of the missionare to expand the scientific knowledge about the origin andevolution of moon, upgrade India.s technological capabilities andprovide challenging opportunities to the young scientists workingin planetary sciences.2.What Chandrayaan-1 aims to accomplish?a)Looking for water ice b) The manoeuvres c) To study moon’s origin d) Lunar gravity e) Looking for minerals 3. Scientific Objectives:The Chandrayaan-1 mission is aimed at high-resolution remote sensing of the moon in visible, near infrared (NIR), low energy X-rays and high-energy X-ray regions. Specifically the objectives are
a) To prepare a three-dimensional atlas (with high spatial and altitude resolution of 5-10 m) of both near and far side of the moon. b) To conduct chemical and mineralogical mapping of the entire lunar surface for distribution of mineral and chemical elements such as Magnesium, Aluminum, Silicon, Calcium, Iron and Titanium as well as high atomic number elements such as Radon, Uranium & Thorium with high spatial resolution.4. Introduction of Mission:Chandrayaan-1 spacecraft was launched from the Satish Dhawan Space Centre, SHAR, Sriharikota by PSLV-XL (PSLV-C11) on 22 October 2008 at 06:22 hrs IST.5.Chandrayaan Mission Profile:6)Spacecraft for lunar mission is:7)Technology used in making our spacecraft:Terrain Mapping Camera (TMC)a)The aim of TMC is to map topography of both near and far side of the Moon and prepare a 3-dimensional atlas with high spatial and elevation resolution of 5 m.b) The TMC will image in the panchromatic spectral region of 0.5 to 0.85 µm, with a spatial/ ground resolution of 5 m and swath coverage of 20 km.c) The camera is configured for imaging in the pushbroom mode, with three linear 4k element detectors in the image plane for fore, nadir and aft views, along the ground track of the the satellite.d) TMC uses Linear Active Pixel Sensor (APS) detector with in-built digitizer. Single refractive optics will cover the total field of view for the three detectors.e) Modular camera electronics for each detector is custom designed for the system requirements using FPGA. The expected data rate is of the order of 50 Mbps. The dimension of TMC payload is 370 mm x 220 mm x 414 mm and mass is 6.3 kg.Hyper Spectral Imager (HySI)a)The data from this instrument will help in improving the available information on mineral composition of the surface of Moon.b) study of data in deep crater regions/central peaks, which represents lower crust or upper mantle material, will help in understanding the mineralogical composition of Moon’s interior.c) The uniqueness of the HySI is in its capability of mapping the lunar surface in 64 contiguous bands in the VNIR, the spectral range of 0.4-0.95 µm region with a spectral resolution of better than 15 nm and spatial resolution of 80 m, with swath coverage of 20 km.d) HySI will collect the Sun’s reflected light from the Moon’s surface through a tele-centric refractive optics and focus on to an APS area detector for this purpose.e) . An Active Pixel Sensor (APS) area array detector with built-in digitizer would map the spectral bands. The payload mass is 2.5 kg and its size is 275 mm x 255 mm x 205 mm.Lunar Laser Ranging Instrument (LLRI)The primary objective is to demonstrate the technologies required for landing the probe at a desired location on the Moon and to qualify some of the technologies related to future soft landing missions. Major Objectives:Design, development and demonstration of technologies required for impacting a probe at the desired location on the Moon.Qualify technologies required for future soft landing missions.Scientific exploration of the Moon from close range.There will be three instruments on the Moon Impact ProbeRadar Altimeter – for measurement of altitude of the Moon Impact Probe and for qualifying technologies for future landing missions. The operating frequency band is 4.3 GHz ± 100 MHz.Video Imaging System – for acquiring images of the surface of the Moon during the descent at a close range. The video imaging system consists of analog CCD camera.Mass Spectrometer – for measuring the constituents of tenuous lunar atmosphere during descent. This instrument will be based on a state-of-the-art, commercially available Quadrupole mass spectrometer with a mass resolution of 0.5 amu and sensitivities to partial pressure of the order of 10-14 torr. Impact Probe profile.Chandrayaan-1 X-ray Spectrometer (C1XS)a)The primary goal of the C1XS instrument is to carry out high quality X-ray spectroscopic mapping of the Moon, in order to constrain solutions to key questions on the origin and evolution of the Moon.b) The instrument utilises technologically innovative Swept Charge Device (SCD) X-ray sensors, which are mounted behind low profile gold/copper collimators and aluminium/polycarbonate thin film filtersc) The system has the virtue of providing superior X-ray detection, spectroscopic and spatial measurement capabilities, while also operating at near room temperature.d) A deployable proton shield protects the SCDs during passages through the Earth’s radiation belts, and from major particle events in the lunar orbit.e) . In order to record the incident solar X-ray flux at the Moon, which is needed to derive absolute lunar elemental surface abundances, C1XS also includes an X-ray Solar Monitor.8. Basic Information: Prime Objectives Payload • Search for water-ice MiniSAR, HEX, SARA • Chemical Mapping C1XS, HEX • Mineralogical Mapping HySI, SIR-2, M3 • Topography Mapping LLRI,TMC • Radiation Environment RADOM, HEX, C1XS • Magnetic Field Mapping SARA • Volatile Transport HEX • Lunar Atmospheric constituent MIP9. Some of latest results from our missioncraft:
Crater Visualisation from TMC images
2.5D Visualisation of Coulomb C Crater by TMC
Hyper Cube
10. Conclusion:
Lunar Laser Ranging Instrument (LLRI) proposed for the first Indian lunar mission Chandrayaan-1 is aimed to study the topography of the Moon’s surface and its gravitational field by precisely measuring the altitude from a polar orbit around the Moon. Altimetry data close to the poles of the Moon would also be available from the instrument, which was not covered by earlier missions. This instrument supplements the terrain mapping camera and hyperspectral imager payloads on Chandrayaan-1. The instrument consists of a diode pumped Nd:YAG pulsed laser transmitter having 10 nsec pulse width and a receiver system. The receiver system features 17 cm diameter Ritchey—Chrétien collecting optics, Si Avalanche Photo Detector (APD), preamplifiers, constant fraction discriminators, time-of-flight measurement unit and spacecraft interface. Altimeter resolution of better than 5 m is targeted. The received signal strength of LLRI depends on laser pulse backscatter from the Moon’s surface. Moon’s surface being a poor reflector, the choice of receiver size and its type and the selection of detector play an important role in getting a good signal-to-noise ratio and in turn achieving the target resolution. At the same time, the spacecraft puts a limitation on payload size and weight. This paper discusses the proposed LLRI system for Chandrayaan-1 and signal-to-noise ratio estimation