an initial elliptical orbit around the Earth by PSLV-C11 on October 22, 2008. This was followed by four orbit raising manoeuvres, which together raised Chandrayaan-1's orbit to a much higher altitude. The spacecraft is now circling the Earth in an orbit whose apogee (farthest point to Earth) lies at 267,000 km (Two lakh sixty seven thousand km) and perigee (nearest point to Earth) at 465 km. In this orbit, Chandrayaan-1 takes about six days to go round the Earth once. The spacecraft performance is being continuously monitored and is normal.
Once in GTO, Chandrayaan's on-board motor will be fired to increase its orbit around the earth. The orbit will be raised five times till it reaches 1,019 km perigee and 386,194 km apogee from the Earth on 8 November.
This orbit will take the spacecraft to the vicinity of the moon. The spacecraft will rotate for about five-and-a-half days before firing the engine to slow its velocity for moon's gravity to capture it. As the spacecraft approaches the moon, its speed will be reduced to enable the gravity of the moon to capture it into an elliptical orbit. A series of engine burns will then lower its orbit to its intended 100 km circular polar orbit. Following this, the Moon Impact Probe (MIP) will be ejected from Chandrayaan-1 and all the scientific instruments/payloads are commissioned.
Chandrayaan-1 completed four orbits around the Earth, on 23 October: "The health of the spacecraft is normal and (it is) doing fine. Spinning in elliptical orbit once in every 6 hours and 30 minutes, it has completed four orbits and is in the fifth orbit."
The successful launch of India's maiden unmanned mission to the moon, Chandrayaan-I could throw new light on the formation of Earth's natural satellite. This is one of the main reasons why all the scientists in the country are excited about the launch.
A popular theory about the moon's formation is that a collision between Mars and Earth threw up a large amount of debris which later became the moon.
"Now with the unmanned mission to the moon, scientists will be able to test this theory by mapping the moon," said Dipankar Bhattacharya, astronomer at the Inter University Center for Astronomy and Astrophysics, University of Pune.
Orbiting mission
Explaining how this moon mission is different from earlier ones, Bhattacharya said, "The earlier missions were landing missions. The problem with the landing mission is one can investigate only a specific area. But this is an orbiting mission where the entire topography of the moon will be mapped for two years."
Chandrayaan-I, with 11 payloads, one of the most heavily loaded lunar missions, is unique as it will try to map high resolution 3-D topography of the moon's surface, get mineral composition of the same, investigate the presence or absence of water and the chemical composition of the Earth's satellite.
Chandrayaan-I would establish India's credentials as a leader in space technology, including indigenous development of powerful launch vehicles and spacecraft.
With the successful launch of Chandrayaan-I, India now has joined an exclusive club of nations including the US, former Soviet Union, European Space Agency, China and Japan to have sent missions to the moon.
The spacecraft was put into orbit exactly 18.2 minutes after its launch at 6.22 am from Satish Dhawan Space Center, Sriharikota. At Rs 386 crore, the Indian mission is considered to be the cheapest in the world, which will help generate the first-ever comprehensive maps of the earth's only natural satellite.
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