Geosynchronous
Satellite Launch Vehicle (GSLV-D5), carrying communication satellite GSAT-14,
has been launched successfully from the Satish Dhawan Space Centre in
Sriharikota, Andhra Pradesh at 4:18 pm today. After Indian Space ResearchOrganisation’s successful launch of its first rocket
to Mars, all eyes are now glued on whether the GSLV-D5, powered by its own
crucial cryogenic engine, would be successful or not.
The last attempt, in August 2013,
was dramatically scrubbed a couple of hours before liftoff, when launch
officials detected a leak in the hydrazine fuel system on the rocket’s second
stage. So a successful return-to-flight of the GSLV programme this weekend would loft into orbit much more than a
communication satellite: the rocket would carry aloft the spirit of India’s
space scientists. Standing 161 feet tall and weighing 640 tonne at liftoff, the GSLV-D5 belongs to the
GSLV-Mk III series and is the heaviest rocket built in India.
After
the last launch attempt failed, Isro engineers worked tirelessly to redesign
the launcher’s liquid hydrogen-fuelled second stage. They seem to be leaving
nothing to chance this time round, swarming all over the launcher with
technical toothcombs to ensure an uninterrupted countdown
and liftoff.
“The solid first stage and core base shroud have also been
inspected and the affected elements replaced. The vehicle’s four strap-on
engines, too, have been replaced,” says S Somnath, GSLV-Mk III’s project
director.
The most important objective of the GSLV-D5 mission, however, is
to flight-test the rocket’s all-important third stage: the indigenously-built
cryogenic upper stage (CUS). The CUS, expected to be the mainstay of future
GSLV flights, replaces the Russian cryogenic engine which was used in the
rocket’s earlier experimental flights.
There will be a
lot of crossed fingers at Sriharikota during the
launch, considering the new engine had a disastrous maiden flight in April
2010, shutting down less than a second after ignition, with the rocket plunging
into the sea. The GSLV’s significance lies in the fact that the future of the
global satellite market lies in the field of communications. The GSAT 14
satellite piggybacking the GSLV-D5 carries six Ku-band and six extended C-band
transponders to help in digital audio broadcasting and other communications
across the entire subcontinent.
Designed
to last for a dozen years in its orbit, the satellite will replace the GSAT-3
(EDUSAT) which has been in orbit for 10 years.
The big boosters in the GSLV series can hoist heavy communication
satellites into geosynchronous orbits 36,000 km above the equator. In this
position, the satellite keeps pace with Earth’s rotation and, as a result,
appears stationary from the ground. This makes it easier to build simpler
antennas on the ground, which do not have to track moving satellites in the
sky. But powerful GSLV Mark IIIs (like the GSLV-D5) that can carry five-tonne
satellites need cryogenic engines.
These
engines use fuels like oxygen and hydrogen in liquid form — stored at extremely
low temperatures — to produce enormous amounts of thrust per unit mass
(engineering parlance for the mass of fuel the engine requires to provide
maximum thrust for a specific period such as, say, pounds of fuel per hour per
pound of thrust).
Rockets powered by cryogenic motors, therefore, need to carry
much less fuel than would otherwise be required. Cryogenic fuels are also
extremely clean as they give out only water while burning. A successful GSLV-D5
flight will make India only the sixth nation to possess this cutting edge
technology, joining the United States, Russia, France, Japan and China in an
elite club.
India’s cryogenic
motor development encountered some rough weather in 1993 when exaggerated US
jitters — that India might utilise its space capabilities for military
purposes — led to Moscow chickeningout
of a cryo-engine technology transfer deal with New Delhi.
Of course, the real reason for guarding cryogenic engine
technology so zealously probably had more to do with economics than national
security. India’s arrival in the global heavy-lift launch market as a low cost
launch source would have threatened the business interests of Europe, Russia,
and the US. In hindsight, though, it seems to have been a disguised blessing
for Indian scientists who were forced to develop the technology on their own. The
GSLV will reduce India’s dependence on foreign launchers like the ESA’s Ariane
to launch INSAT-class satellites.
Isro sources speak of
plans to fly two more GSLVs at six-month-intervals
before using the third one for the Chandrayaan-2 Moon mission. The GSLV-Mark
III is also earmarked for launching human space flights in future and building
orbiting space stations.
Isro has built up an impressive portfolio of comparatively cheap
space products and services that are attractive to foreign space agencies that
want to outsource space missions.