In its fourteenth flight conducted from Satish Dhawan Space
Centre (SDSC) SHAR, Sriharikota this morning
22, 2008), the Indian Space Research Organisation’s
(ISRO’s) Polar Satellite Launch Vehicle, PSLV-C11, successfully launched
the 1380 kg
Chandrayaan-1 spacecraft into a transfer orbit with a perigee (nearest
point to Earth) of 255 km and an apogee (farthest point to Earth) of 22,860 km,
inclined at an angle of 17.9 deg to the equator.
After a 52 hour count down, PSLV-C11 lifted off from the Second
Launch Pad at SDSC SHAR at 06:22 Hrs Indian Standard Time (IST) with the
ignition of the core first stage. The important flight events included the
separation of the first stage, ignition of the second stage, separation of the
payload fairing at about 116 km altitude after the vehicle had cleared the
dense atmosphere, second stage separation, third stage ignition, third stage
separation, fourth stage ignition and fourth stage cut-off.
PSLV-C11 is the uprated version of ISRO's Polar Satellite Launch
Vehicle in its standard configuration. Weighing 320 tonnes at lift-off, the
vehicle uses larger strap-on motors (PSOM-XL) to achieve higher payload
capability. PSOM-XL uses 12 tonnes of solid propellants instead of 9 tonnes
used in the earlier configuration of PSLV. PSLV is a four stage launch vehicle
employing both solid and liquid propulsion stages. PSLV is the trusted
workhorse launch Vehicle of ISRO. During 1993-2008 period, PSLV had fourteen
launches of which thirteen (including today’s launch) are consecutively
successful. PSLV has repeatedly proved its reliability and versatility by
launching 30 spacecraft (14 Indian and 16 for international customers) into a
variety of orbits so far.
Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed
and developed PSLV. ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram
developed the inertial systems. The Liquid Propulsion Systems Centre (LPSC),
also at Thiruvananthapuram, developed the liquid propulsion stages for the
second and fourth stages of PSLV as well as reaction control systems. SDSC SHAR
processed the solid propellant motors and carried out launch operations. ISRO
Telemetry, Tracking and Command Network (ISTRAC) provided telemetry, tracking
and command support.
Chandrayaan-1 is India's first spacecraft mission beyond Earth's
orbit. It aims to further expand our knowledge about Earth's only natural
satellite – the moon. With well-defined objectives, Chandrayaan-1 mission
intends to put an unmanned spacecraft into an orbit around the moon and to
perform remote sensing of our nearest celestial neighbour for about two years
using eleven scientific instruments built in India and five other countries.
The primary objectives of Chandrayaan-1 are:
To place an unmanned spacecraft in an orbit
around the moon
To conduct mineralogical and chemical mapping
of the lunar surface
To upgrade the technological base in the
Chandrayaan-1 aims to achieve these well-defined objectives through
high-resolution remote sensing of moon in the visible, near infrared, microwave
and X-ray regions of the electromagnetic spectrum. With this, preparation of a
3-dimensional atlas of the lunar surface and chemical and mineralogical mapping
of entire lunar surface is envisaged.
PSLV placed the Chandrayaan-1 spacecraft into a highly elliptical
Transfer Orbit (TO) around the earth. Later, through a series of highly complex
manoeuvres, the desired trajectories will be achieved. After circling the Earth
in its Transfer Orbit, Chandrayaan-1 spacecraft will be taken into more
elliptical ‘Extended Transfer Orbits’ by repeatedly firing its
Liquid Apogee Motor (LAM) in a pr-determined sequence. Subsequently, the LAM is
again fired to make the spacecraft to travel to the vicinity of the moon.
When it reaches the vicinity of the Moon and passes at a few
hundred kilometers from it, its LAM is fired again so that the spacecraft slows
down sufficiently to enable the gravity of the moon to capture it into an
Following this, the height of the spacecraft's orbit around the
moon is reduced in steps. After a careful and detailed observation of the orbit
perturbations there, the orbital height of Chandrayaan-1 will be finally
lowered to its intended 100 km height from the lunar surface. Moon Impact Probe
will be ejected from Chandrayaan-1 spacecraft at the earliest opportunity to
hit the lunar surface in a chosen area.
Later, cameras and other scientific instruments are turned ON and
thoroughly tested. This leads to the operational phase of the mission. This
phase lasts for about two years during which Chandrayaan-1 spacecraft explores
the lunar surface with its array of instruments that includes cameras,
spectrometers and SAR.
There are 11 payloads (scientific instruments) through which Chandrayaan-1
intends to achieve its scientific objectives.
They include five instruments designed and developed in India,
three instruments from European Space Agency (one of which is developed jointly
with India and the other with Indian contribution), one from Bulgaria and two
from the United States.
The Indian payloads of Chandrayaan-1 are:
Terrain Mapping Camera (TMC), a CCD camera that maps the
topography of the moon, which helps in better understanding of the lunar
Hyperspectral Imager (HySI), another CCD camera, is designed for
mapping of the minerals on the lunar surface as well as for understanding the
mineralogical composition of Moon’s interior.
Lunar Laser Ranging Instrument (LLRI) provides necessary data for
accurately determining the height of lunar surface features.
High Energy X-ray Spectrometer (HEX) is designed to help explore
the possibility of identifying Polar Regions covered by thick water-ice
deposits as well as in identifying regions of high Uranium and Thorium
Moon Impact Probe (MIP) demonstrates the technologies required
for landing a probe at the desired location on the moon. It is also intended to
qualify some of the technologies related to future soft landing missions.
The six international payloads of Chandrayaan-1 are:
Chandrayaan-1 Imaging X ray Spectrometer (C1XS), an ESA payload
and jointly developed by Rutherford Appleton Laboratory of England and ISRO
Satellite Centre, Bangalore, intends is to carry out high quality mapping of
the moon using X-ray fluorescence technique for finding the presnce of
Magnesium, Aluminium, Silicon, Iron and Titanium distributed over the surface
of the Moon.
Smart Near Infrared Spectrometer (SIR-2), another ESA payload,
developed by Max Plank Institute of Germany, aims to study the lunar surface to
explore the mineral resources and the formation of its surface features.
Sub kiloelectronvolt Atom Reflecting Analyser (SAR), the third
payload from ESA, is built by Swedish Institute of Space Physics and Space
Physics Laboratory of Vikram Sarabhai Space Centre, Tiruvananthapuram. The aim
of this instrument is to study the surface composition of the moon and the
magnetic anomalies associated with the surface of the moon.
Radiation Dose Monitor (RADOM), a payload developed by Bulgarian
Academy of Sciences, aims to characterise the radiation environment in a region
of space surrounding the moon.
Mini Synthetic Aperture Radar (MiniSAR) is one of the two
scientific instruments from the USA and is from Johns Hopkins University's
Applied Physics Laboratory and Naval Air Warfare Centre, USA through NASA.
MiniSAR is mainly intended for detecting water ice in the permanently shadowed
regions of the lunar poles up to a depth of a few meters.
Moon Mineralogy Mapper (M3) is an imaging spectrometer from Brown
University and Jet Propulsion Laboratory of the US through NASA, is intended to
assess and map lunar mineral resources at high spatial and spectral resolution.
Chandrayaan-1 spacecraft weighed about 1380 kg at the time of its launch and is
a 1.5 m cuboid with a solar panel projecting from one of its sides. The
spacecraft is powered by a single solar panel generating electrical power of
700 W. A Lithium ion battery supplies power when the solar panel is not
illuminated by the sun. To make Chandrayaan-1 spacecraft to travel towards the
Moon, its Liquid Apogee Motor (LAM) is used. Liquid propellants needed for LAM
as well as thrusters are stored onboard the spacecraft. Chandrayaan-1
spacecraft's Dual Gimballed Antenna transmits the scientific data gathered by
its eleven scientific instruments to Earth.
Chandrayaan-1 spacecraft was built at ISRO Satellite Centre,
Bangalore with contributions from Vikram Sarabhai Space Centre (VSSC), Liquid
Propulsion Systems Centre (LPSC) and ISRO Inertial Systems Unit (IISU) at
Tiruvananthapuram, Space Applications Centre (SAC) and Physical Research
Laboratory (PRL), Ahmedabad and Laboratory for Electro-optic Systems (LEOS),
The Ground Segment:
The Ground facilities of Chandrayaan-1 perform the important task of receiving
the health information as well as the scientific data from the spacecraft. It
also transmits the radio commands to be sent to the spacecraft during all the
phases of its mission. Besides, it processes and stores the scientific data
sent by Chandrayaan-1 spacecraft.
ISRO Telemetry, Tracking and Command Network (ISTRAC) had a lead
role in establishing the Ground Segment of Chandrayaan-1 with contributions
from ISAC and SAC. The Ground Segment of Chandrayaan-1 consists of:
Indian Deep Space Network (IDSN)
Spacecraft Control Centre (SCC)
Indian Space Science Data Centre (ISSDC)
The Indian Deep Space Network
receives the data sent by the Chandrayaan-1 spacecraft. Besides, it sends
commands to the spacecraft at a power level of upto 20 kilowatts. IDSN consists
of two large parabolic antennas – one with 18 m diameter and the other 32
m diameter – at Byalalu, situated at a distance of about 35 km from
Bangalore. Of these the 32 m antenna with its ‘seven mirror beam
waveguide system’, was indigenously designed, developed, built,
installed, tested and qualified. The 18 m antenna can support Chandrayaan-1
mission, but the 32m antenna can support spacecraft missions well beyond Moon.
The Spacecraft Control
Centre, located near the ISTRAC campus at Peenya, North of Bangalore,
is the focal point of all the operational activities of Chandrayaan-1 during
all the phases of the mission.
The Indian Space Science Data Centre
forms the third element of Chandrayaan-1 ground segment. Also
located at Byalalu, ISSDC receives data from IDSN as well as
other external stations that support Chandrayaan-1, stores,
processes, archives, retrieves and distributes scientific data
sent by Chandrayaan-1 payloads to the user agencies.