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Chennai:
After 16 successful launches of its workhorse rocket Polar
Satellite Launch Vehicle (PSLV) in the last 17 years, the Indian
space agency is now testing a key component to re-qualify its
on-flight performance parameters to avoid any unpleasant
surprises.
The Indian Space Research Organisation (ISRO) is testing the gas
motor which is fitted in the second stage/engine powered by liquid
fuel for high temperature tolerance levels.
The test has forced ISRO to postpone the launch of its remote
sensing satellite Resourcesat-2 and two other payloads by nearly a
month. Remote sensing satellites like Resourcesat send back
pictures and other data for various uses. India is a major player
in providing such data in the global market.
The rocket was scheduled for launch this week.
According to ISRO officials, the gas motor powers the rocket's
second stage control actuators for maneuvering the engine's nozzle
- the process is called gimballing. The process enables the rocket
to maintain a steady course on its way up.
The motor is powered by the hot gases tapped from the rocket.
"During earlier PSLV rocket launches, we had noticed the
temperature of the hot gases at the motor inlet being higher by
20-30 percent while the expected temperature is around or less
than 300 degree celsius," an ISRO official told IANS.
ISRO officials said the space agency's chairman K. Radhakrishnan
wanted to be sure about the parameters of the rocket's subsystems
as he was of the view that ISRO cannot afford another failure and
that too involving the PSLV rocket.
ISRO's commercial arm Antrix Corporation is earning a sizeable
sum, launching third-party satellites using PSLV rockets.
The Indian space agency's last two missions involving its heavy
rocket - Geosynchronous Satellite Launch Vehicle (GSLV) - ended in
failures, resulting in a total loss of around Rs.600 crore - cost
of two rockets and two satellites.
ISRO will be using PSLV to launch a communication satellite till
the space agency stabilises its GSLV rocket that can sling much
heavier satellites into orbit.
According to ISRO officials, the temperature tolerance levels of
the gas motor is being tested in a power generation company near
here.
ISRO opted to test the gas motor's heat tolerance limits as that
will be quicker than redesigning the rocket's engine to bring down
the gas temperature.
"Up to 300 degree celsius we can test the component at ISRO's
centre in Thiruvananthapuram. We do not have super heated steam
generators to test the temperature tolerance levels above that
levels," an official said.
According to him, the test results have been satisfactory till now
as the motor tolerated temperature up to 370 degree celsius.
The test results will be studied and the final call on the
rocket's launch carrying remote sensing satellite Resourcesat-2 is
expected to be taken Feb 28 by Radhakrishnan.
ISRO officials said around 20 days' time is required to test the
rocket's subsystems after the launch permission.
If the permission is given on Mar 1, ISRO would require 20 days
more to make the rocket and the satellite ready for launch.
Meanwhile, the fully assembled PSLV rocket is standing tall at the
Sriharikota launch centre, around 80 km from here. All the three
satellites are also at the rocket launch pad.
India has the largest constellation of remote sensing satellites
in the world providing imageries in variety of spatial resolutions
from better than a metre ranging up to 500 metres.
The remote sensing satellites that are operational are --
Cartosat-2B, Oceansat-2, RISAT-2, Cartosat-2A, IMS-1, Cartosat-2,
Resourcesat-1 and TES.
For some time, Resourcesat-2 and Resourcesat-1 would work together
before the latter would go into oblivion.
Launched in 2003, Resourcesat-1 has outlived its original mission
life of five years.
Compared to Resourcesat-1, the multispectral swath of
Resourcesat-2 has been enhanced from 23 km to 70 km based on user
needs.
Suitable changes, including miniaturisation in payload
electronics, have also been incorporated in Resourcesat-2.
The other remote sensing satellites that ISRO plans to launch are
RISAT, Megha-Tropiques, INSAT-3D, Astrosat -- astronomy satellite
to observe celestial bodies.
(V. Jagannathan can be contacted at v.jagannathan@ians.in)
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