Chennai, Feb 2 (UNI) A Vibration disturbance for a short duration
during the separation of the Second Stage led to the failure of the
maiden developmental flight of the Small Satellite Launch Vehicle
(SSLV-D1) in August last year, the Indian Space Research
Organisation (ISRO) said on Thursday.
This was revealed in Failure Analysis report of SSLV-D1 Mission
submitted to the ISRO.
ISRO said the Failure Analysis Committee, which went into the
failure of the first SSLV mission, said detailed analysis of the
flight events and observations ranging from countdown, lift-off,
propulsion performance, stage separations and satellite injection
revealed that there was a vibration disturbance for a short duration
on the Equipment Bay (EB) deck during the Second Stage (SS2)
separation, that affected the Inertial Navigation System (INS),
resulting in declaring the sensors faulty by the logic in Fault
Detection & Isolation (FDI) software.
It said SSLV is designed to be affordable and amenable to industry
production and will function as a launch-on-demand platform for
Mini, Micro or Nano satellites.
It is a three-stage vehicle with all solid propulsion stages and liquid
propulsion-based Velocity Trimming Module (VTM) as the terminal
stage.
The launcher also targets many novel features including low turn
around time, flexibility in accommodating multiple satellites,
launch-on-demand, minimal launch infrastructure requirements,
etc.
The first developmental flight of SSLV lifted off from Satish Dhawan
Space Centre (SDSC) on August 7, 2022 at 0918 hrs. The objective of
the mission (SSLV-D1/EOS-02) was to inject EOS-02 satellite of ISRO
into a circular orbit of 356.2 km with an inclination of 37.21 deg.
Azaadisat, a student satellite was also accommodated in the mission,
authorized by IN-SPACe.
However, the spacecraft were injected into a highly elliptical unstable
orbit due to a shortfall in velocity, leading to their decay and deorbiting
immediately, in spite of normal performance of all solid propulsion
stages. The orbit achieved was 360.56 km x 75.66 km with an inclination
of 36.56 deg.
Initial investigations with the flight data indicated that the lift-off of SSLV-D1
was normal along with normal performance of all solid propulsion stages.
However, the mission could not be achieved due to an anomaly during
the SS2 separation, which triggered a mission salvage mode (which is
a procedure adopted to attempt minimum stabilized orbital conditions
for the Spacecraft in case of an anomaly in the vehicle system).
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