Chandrayaan-1 - A great leap forward
The successful launch and lunar operations of the first Indian unmanned moon spacecraft Chandrayaan-1 is a remarkable milestone of Indian science. It was the 68th of the lunar missions that began with the Soviet Luna 1 launch on 02 January 1959. The total cost of the mission is approximately $83 million. On landing an impact probe on the moon surface from a lunar orbiting spacecraft India joins the elite club of space fairing nations that include USA, Russia, European Space Agency (ESA), China and Japan. Over the years and especially in the last decade, the Indian Space Research Organization (ISRO) has continued to develop a broad-based indigenous launch vehicles, satellites, control facilities and data processing centers. In realizing its dream, India has demonstrated its capability to design, integrate, launch, and operate complex space and ground systems/sub-systems. ISRO is already moving ahead on its joint Chandrayaan-2 Robotic Lunar Lander mission with Russia. It is also laying plans for a new $122 million launch complex and astronaut training facility pending the expected government approval for a two seat manned Earth orbiter. ISRO has recently (Jan 2007) conducted an unmanned Space Capsule Recovery Experiment to prepare/test for future manned flights. By far the most ambitious space program is the dual use AVATAR a reusable hypersonic launch vehicle (SSTO/TSTO) capable of carrying a 1000kg payload being developed by Defense Research and Development Organization (DRDO). India has been working on air breathing engines (ramjet/scramjet) for a technology demonstrator flight in near future.
In 1975, ISRO launched its first satellite, ‘Aryabhata’, on a Soviet Cosmos-3M rocket, and in 1980, India's first home-built launcher, the SLV-3, successfully put a satellite into orbit. Since 1980 India has used both, its indigenous launch capabilities, and commercial launch vehicles (mostly from Soviet Union) to launch a series of Remote Sensing (IRS, CARTOSAT) and Communication Satellites (INSAT). India’s attempts to launch its own Geosynchronous Satellite have been less than stellar. After several failed attempts the Geosynchronous Satellite Launch Vehicle (GSLV) was finally able to launch the INSAT-4CR in the geosynchronous orbit. GSLV uses a Russian cryogenic upper stage, which India had serious difficulty in developing. Under a Russia-India joint venture, India will launch two GLONASS-M satellites on its GSLV platforms and share costs of developing the K-series satellites. India has also been granted access to the military band of GLOSNASS signal. Although ISRO does not have a mandate to build military satellites, the TES & CARTOSAT satellites deliver military quality 1-meter imagery effectively. According to reports CARTOSAT-2A is equipped with an Israeli made advanced synthetic aperture radar (SAR). The hallmark of India-Israel space collaboration was the launch of Iran specific TECSAR/Polaris spy satellite by the Indian PSLV launch vehicle. Weighing less than 300 kilograms, the TECSAR employs synthetic aperture radar (SAR) technology and provides day and night image resolution of up to 10 centimeters, even in cloudy weather.
The Chandrayaan-1 is a two year mission aimed at high-resolution remote sensing of the moon in visible, near infrared (NIR), low energy X-rays and high-energy X-ray regions. The objective is 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. In addition, it will conduct chemical and mineralogical mapping of the entire lunar surface for distribution of mineral and chemical elements including high atomic number elements such as Radon, Uranium and Thorium with high spatial resolution.
The Chandrayaan-1 spacecraft bus is 1.5 meters cube, 3-axis stabilized, with two star trackers, gyros and four reaction wheels. The total mass at launch was 1380 kg and a dry mass of 675 kg at lunar orbit. A bipropellant (MMH/MON-3) propulsion system is used to transfer Chandrayaan-1 into lunar orbit and maintain attitude. The spacecraft design is based on ISRO’s Kalpansat meteorological satellite that was launched in 2002. The 750 Watt solar panel together with a Lithium-Ion battery is used to supply power to the spacecraft. The spacecraft uses the X-band transmission for payload data and a separate S-band link for Telemetry Tracking and Command. Three solid state recorders are used to store payload data. Chandrayaan-1 at the satellite processing center is shown below.
Chandrayaan-1 payload comprises of five instruments from India, three from ESA two from NASA and one from Bulgaria. The NASA instruments are: (a) Miniature Synthetic Aperture Radar (MiniSAR) build by Applied Physics Laboratory, Johns Hopkins University and (b) Moon Mineralogy Mapper (M3) payload is from Brown University and Jet Propulsion Laboratory. The details of these scientific payloads are available at http://www.isro.org/Chandrayaan/htmls/psexperiments.htm. As the spacecraft faces the sun, these instruments are being switched on/off to maintain the temperature of the spacecraft. The spacecraft’s only launch-able payload; a 30 kg lunar impact probe was released on Nov 14 as a prelude for future hard and soft landing. The frequency range coverage provided by the on board instruments are shown below.
Chandrayaan-1 spacecraft was launched from the Satish Dhawan Space Centre, SHAR, Sriharikota by PSLV-XL (PSLV-C11) on 22 October 2008 in an highly elliptical orbit with perigee (nearest point to the Earth) of 255 km and an apogee (farthest point from the Earth) of 22,860 km, inclined at an angle of 17.9 deg to the equator. In this initial orbit, Chandrayaan-1 orbited the Earth once in about six and a half hours. Subsequently multiple (five) Liquid Apogee Motor (LAM) firings at the perigee were used to raise the orbit to the Lunar Transfer Trajectory of 380,000 km in deep space.
To insert the spacecraft in the lunar orbit the liquid engine was fired to reduce its velocity sufficiently which enabled the lunar gravity to capture the spacecraft. As a result, the spacecraft was in an elliptical lunar orbit with periselene (nearest point to the moon) of 504 km and aposelene (farthest point from the moon) of 7,502 km. A series of three orbit reduction maneuvers were successfully carried out to reduce the spacecraft’s orbit to its intended operational circular polar orbit of 100 km.
One of the key elements of the Indian Space Program is the 140 ft Polar Satellite Launch Vehicle (PSLV) build by Vikram Sarabhai Space Center (VSSC) Thiruvananthapuram, Kerala. The launch vehicle program goes back to Dr. A.P.J. Abdul Kalam’s visit to NASA's Langley Research Center, where the United States Scout rocket was developed, and the Wallops Island Flight Center, where the Scout was flown. Kalam then proceeded to build India's first big rocket and domestic satellite launch vehicle, the SLV-3, which is believed to be a virtual replica of the Scout rocket based on the blueprints Kalam saw while in the U.S. and design information that NASA subsequently shared at India's request. The first stage of the SLV-3, first launched in 1979, was then used as the first stage of the Agni missile, India's largest nuclear-capable missile, for which Kalam was the chief designer. The liquid fluid propulsion technology came from France’s Viking rocket motor used in the ESA Ariane satellite launcher.
The lessons learned during the development of earlier launch vehicles i.e. SLV and ASLV have contributed heavily in development of PSLV. Plagued with initial failures, the PSLV was finally successful in launching its first Indian made Remote Sensing Spacecraft in 1996. Since then the PSLV has been successful in launching twenty nine spacecrafts in its thirteen launches for various Low Earth Observation (LEO) and experimental missions.
The PSLV was developed to launch 1000 kg class payload in the Sun Synchronous (99 deg inclination) and other low earth orbits. The four stage vehicle core employs solid (1 & 3) and liquid (2 & 4) propulsion stages alternatively, a rather unusual design, with six strap-on booster. The large solid first stage develops approximately 4,800 kN of thrust. The payload capacity of the PSLV (C11) was increased (for the 1.4 ton Chandrayaan-1) by adding larger solid rocket boosters capable of carrying 12 tons of solid propellant.
The ground communication infrastructure namely the Indian Deep Space Network (IDSN) was built at Byalalu, Bangalore mainly to support interplanetary space missions (100,000 km beyond earth) like Chandrayaan-1. The low earth orbit Indian satellites are controlled by the S-band ISTRAC network stations. The IDSN has the responsibility of receiving the Chandrayaan-1 health and payload data in real time during two years of operation. The network consists of an 18-m and 32-m antennae, with multiple carrier X-band and S-band uplink/downlink capabilities with fiber link to mission operation complex. As a preparation for Chandrayaan-1 lunar mission, IDSN was set up to transmit and receive signals from the Japanese lunar mission Selene (Koguya) and an ESA space probe called Rosetta. For extended visibility and early launch operations the IDSN was augmented by NASA Jet Propulsion Lab (JPL), Applied Physics Lab (APL) and Bearslake, Russia tracking stations. Spacecraft twenty-four command and control is provided by the Mission Operations Complex and the Indian Space Science Data Center, provides payload data processing.
The Indian Space Research Organization (ISRO) was established in 1969 under the Department of Space with headquarters at Bangalore, it employs a workforce of approximate 20,000. The ISRO Satellite Center (ISAC) in Bangalore is responsible for the design, development, assembly, and testing of satellites. The Vikram Sarabhai Space Center (VSSC) develops rocketry and launch vehicle technologies. The spacecraft mission operations are being carried out from the Satellite Control Centre (SCC) of ISRO Telemetry, Tracking and Command Network (ISTRAC) at Bangalore. The development of the sensors and payloads is the responsibility of ISRO's Satellite Application Center (SAC) in Ahmadabad. All Indian space launches are conducted from the Sriharikota High Altitude Range (SHAR) on Sritharikota Island off the east coast of India in the Bay of Bengal.
The Indian Space Research Organization (ISRO) http://www.isro.org
The National Aeronautics and Space Administration http://www.nasa.gov
Space News http://www.spacenew.com
Aviation Week and Space Technology http://www.aviationweek.com/aw/index.jsp
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