With the successful operational launch
of GSLV F-05 rocket that hoisted the meteorological satellite INSAT-3DR into
the geostationary transfer orbit (GTO), ISRO has entered into a new phase of
self-reliance. Till now, PSLV (Polar Satellite Launch Vehicles), the trusted
workhorse adorned the prestigious crown of ISRO with over consecutive 30
successful launches. PSLV could hoist satellites weighing few kilograms to less
than 1400kg limiting ISRO’s capability of launching heavy satellites. PSLV are
capable of carrying remote sensing satellites which are lighter and are placed
in polar orbits. These satellites weigh from few hundred kilograms to about a
tonne. Polar orbits are orbits in which satellites don’t move in tandem with
the rotation of the earth and hence they are not suitable for communication.
The cost efficiency and the reliability of PSLV has been established in the
segment of the smaller satellites. India already boasts of 30 to 35% cheaper launches than other countries. Whereas
Communication satellites are heavier, weigh 2 to 5 tons and need big boosters.
GSLV series of vehicles are designed to hoist heavy satellites into the
geosynchronous orbits 36,000km above the equator, where the satellite moves in
tandem to earth’s rotation and hence service of satellite is available to the
user all the time. GSLV (Geosynchronous Launch Vehicle) can carry satellites
weighing over 1.5 tonnes to 4 tonnes. For heavier satellites of over 4 tonnes
India employs Ariane-6 rocket of European Space Agency. Satellite launching
services of foreign providers are very high. ISRO with three consecutive
successful launches can now induct GSLVs for launch of heavy commercial
satellites. Previous successful launches with the indigenous cryogenic engines
were GSLV-D5 of January 2014 and GSLV-D6 August 2015 that launched GSAT-14 and
GSAT-6 satellites into the designated orbits.
About the Launch & Satellite
The 49 meter- long, GSLV MkII,
weighing 450 tons, powered by an indigenous cryogenic engine CE-7.5, lifted off
from the second launch pad of Satish Dhawan Space Centre, Sriharikota delivered
the satellite with remarkable precision. Launch was delayed by 40 minutes due
to gas leak in a ground circuit. INSAT-3DR weighed 2211 kg of which 1225 kg is
propellant. The propellant helps in satellite to fire up from the GTO to
geostationary orbit and to maintain the satellite in the orbit slot during its
life time. It is an advanced satellite with an imaging system, an atmospheric
Sounder, Data-Relay Transponder & Satellite-aided search and Rescue
Transponder. Imaging system with infrared and color camera can provide better
night time pictures, images storms. Camera will take images every 26 minutes
and its life span is 10 years. Sounder
would collect data on humidity, temperature and ozone data from different
layers of atmosphere. The satellite has solar arrays, generating power. This
satellite will track storms and tropical cyclones, will relay data from remote
weather stations and ocean buoys to weather forecast centers, precisely
indicate distress signals from ships and planes, aiding in search and rescue
operations. INSAT-3DR will supplement the services of INSAT-3D launched in
2013. INSAT-3DR now joins the
conglomerate of meteorological satellites operated by ISRO- KALPANA, INSAT-3A
and INSAT-3D.
Teething Problems with GSLV
India’s tryst with GSLV which began in 1986 was beset with many
obstacles. When India announced its decision to start the project, several
countries stepped forward to help and train personnel. Indeed, US and French
companies had put forth their proposals. But India declined them because of
high costs. Eventually India clinched an agreement with Russian company
Glavkosmos by 1990 for supply of seven cryogenic engines of 7.5 tons thrust
along with the transfer of cryogenic technology. But in 1993 irked by the
Indo-Russian deal, US severely objected Russia selling cryogenic technology to
India as this would be a violation under the Missile Technology Control regime
(MTCR). As per MTCR guidelines, members established a “no undercut”
policy means if a member denies sale of technology to another country, then the
policy has to be strictly adhered by all other members. Further developed countries felt that their business
interests would be severely threatened by India’s entry into the heavy
satellite-launch business. Under pressure Russian company backed off
from transferring technology, but supplied cryogenic engines and an additional
mock-up engine. As a result,
ISRO had to single-handedly sweat out to the technology which was zealously
protected by all nations. Indigenous engines were eventually built at Liquid
Propulsion Systems Centre, Thiruvananthapuram.
GSLV Variants
GSLV is a three stage launcher
and ISRO has three variants- MkI, MkII, MkIII. All these variants have the solid-fuel
first stage and a liquid fuel second stage powered by Vikas engine. The third
stage of MkI uses the Russian cryogenic engines while the third stage CUS
(Cryogenic Upper Stage) of MkII and MkIII have the indigenously developed
engines CE-7.5 and CE-2- respectively. MkIII developmental flight is scheduled
for launch by December 2016 is capable of carrying much heavier payloads. It
will piggy-back GSAT-19 communication satellite. Once MkIII also establishes
its reliability India will be become self-sufficient in terms of launching
capacities. GSLV F-05 is an MkII variant capable of carrying payloads of around
2.5 tons. MkII has assured ISRO of its reliability during its two developmental
flights. Unlike in developmental flight, during operational flight (the current
launch) flight parameters (like altitude, relative velocity, time etc) or
flight routes will not be tested.
Cryogenic Technology
Cryotechnology is incredibly
difficult. In general, three types of rocket fuels are used- Solid, Liquid and
gaseous. Solid fuels despite releasing more amount of energy than liquids are
not preferred because of their high density. Liquid fuels flow and release more
energy than gaseous fuels. It is established that when hydrogen gas burns in presence
of oxygen, the combustion reaction generates 30% more thrust than other rocket
fuels. In cryogenic technology, both hydrogen and oxygen are cooled to such a
low temperature that they become liquids, occupy less space and start flowing.
Hydrogen and Oxygen are liquefied under very low temperatures. Hydrogen is
cooled to -253°C and Oxygen to -183°C and stored in pressurized chambers with
extreme care as they are brittle, explosive in nature and can evaporate
quickly. These propellants can’t be pumped into combustion chambers using
normal pumps, special turbo pumps are to be employed. All operations must be
condensation free. Presence of moisture can be disastrous for a launch. The magnitude of the extreme complexity is truly onerous.
So far ISRO
conducted 10 launches with GSLV starting with GSLV-D1 (Mk1) in April 2001. Of
which four launches have failed, one was a partial success and with the latest
meticulous launch India seems to have tamed the “naughty boy” (GSLV fondly recalled
by Indian scientists) GSLV. With this success, ISRO is now geared to launch second robotic
mission to Moon Chandrayaan-2 in 2018 with a GSLV MkII variant. Moreover, with
Space X’s Falcon 9 exploding ahead of its scheduled flight, global markets are
experiencing the crunch of reliable launch vehicles for heavy satellites. GSLV
F-05 successful launch boosted and substantially improved ISRO’s chances of
making a mark in satellite launching services as a reliable player. ISRO’s
reliability with MkIII would further establish its stature as trusted player
facilitating its entry into the $300 billion global satellite-launching
industry.
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