Chandrayaan-1, Indias first unmanned spacecraft
mission to moon, entered lunar orbit today (November 8, 2008). This is the first time that an
Indian built spacecraft has broken away from the Earths gravitational field
and reached the moon. This historic event occurred following the firing of
Chandrayaan-1 spacecrafts liquid engine at 16:51 IST for a duration of 817
seconds. The highly complex lunar orbit insertion manoeuvre was performed
from Chandrayaan-1 Spacecraft Control Centre of ISRO Telemetry, Tracking and
Command Network at Bangalore.
Indian Deep Space Network (IDSN) at Byalalu supported the crucial task of
transmitting commands and continuously monitoring this vital event with two
dish antennas, one measuring 18 m and the other 32 m.
Chandrayaan-1s liquid engine was fired when the spacecraft passed at a
distance of about 500 km from the moon to reduce its velocity to enable lunar
gravity to capture it into an orbit around the moon. The spacecraft is now
orbiting the moon in an elliptical orbit that passes over the polar regions of
the moon. The nearest point of this orbit (periselene) lies at a distance of
about 504 km from the moons surface while the farthest point (aposelene) lies
at about 7502 km. Chandrayaan-1 takes about 11 hours to go round the moon once
in this orbit.
The performance of all the systems onboard
Chandrayaan-1 is normal. In the coming days, the height of Chandrayaan-1
spacecrafts orbit around the moon will be carefully reduced in steps to
achieve a final polar orbit of about 100 km height from the moons surface.
Following this, the Moon Impact Probe (MIP) of the spacecraft will be released
to hit the lunar surface. Later, the other scientific instruments will be
turned ON sequentially leading to the normal phase of the mission.
It may be recalled that Chandrayaan-1 spacecraft was launched on October 22,
2008 by PSLV-C11 from Indias spaceport at Satish Dhawan Space Centre (SDSC)
SHAR, Sriharikota. As intended, PSLV placed the spacecraft in a highly oval
shaped orbit with a perigee (nearest point to Earth) of 255 km and an apogee
(farthest point to Earth) of 22,860 km. In the past two weeks, the liquid
engine of Chandrayaan-1 has been successfully fired five times at opportune
moments to increase the apogee height, first to 37,900 km, then to 74,715 km,
later to 164,600 km, after that to 267,000 km and finally to 380,000km, as
planned. During this period, the Terrain Mapping Camera (TMC), one of the
eleven payloads (scientific instruments) of the spacecraft, was successfully
operated twice to take the pictures, first of the Earth, and then moon.
With todays successful manoeuvre, India becomes the fifth country to send a
spacecraft to Moon. The other countries, which have sent spacecraft to Moon,
are the United States, former Soviet Union, Japan and China. Besides, the
European Space Agency (ESA), a consortium of 17 countries, has also sent a
spacecraft to moon.