Vibration failure led to failure of SSLV – D1

Subject : Science and technology

Section: Space

Concept :

The Indian Space Research Organisation (ISRO) on Wednesday issued an official statement explaining in detail the failure of the first development flight of the Small Satellite Launch Vehicle (SSLV) in August last year.
The space agency also spelt out corrective actions ahead of the launcher’s next development flight – SSLV-D2 – scheduled during the first quarter of 2023.
The objective of SSLV-D1/EOS-02 was to inject ISRO’s EOS-02 satellite and a student satellite, Azaadisat, into a circular orbit of 356.2 km.
However, the spacecraft was 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

Small Satellite Launch Vehicle

Small Satellite Launch Vehicle (SSLV) is a three stage Launch Vehicle configured with three Solid Propulsion Stages and a liquid propulsion-based Velocity Trimming Module (VTM) as a terminal stage.
SSLV is 2m in diameter and 34m in length with a lift-off weight of around 120 tonnes.
SSLV is capable of launching 500kg satellites in 500km planar orbit from Satish Dhawan Space Centre (SDSC).
Key Features:
Low cost,
Low turn-around time,
Flexibility in accommodating multiple satellites,
Launch demand feasibility,
Minimal launch infrastructure requirements, etc.

SSLV-D1/EOS-02 Mission

It was aimed at garnering a larger pie in the small launch vehicles market, as it could place the satellites into Low Earth Orbit.

It was carrying the two satellites on board the rocket –

The primary EOS-2 Earth-observing satellite– EOS-02 is an earth observation satellite designed and realised by ISRO.
This microsat series satellite offers advanced optical remote sensing operating in infra-red band with high spatial resolution.
The secondary AzaadiSAT student satellite– It is an 8U Cubesat weighing around 8 kg.
It carries 75 different payloads each weighing around 50 grams and conducts femto-experiments.
It carried out tiny experiments which would have measured the ionising radiation in its orbit and also a transponder which worked in the ham radio frequency to enable amateur operators to access it.
Girl students from rural regions across the country were provided guidance to build these payloads.
The payloads are integrated by the student team of “Space Kidz India”.

Difference between Circular and Elliptical Orbits

Elliptical Orbits:
- Mostly objects such as satellites and spacecrafts are put in elliptical orbits only temporarily.
- They are then either pushed up to circular orbits at a greater height or the acceleration is increased until the trajectory changes from an ellipse to a hyperbola and the spacecraft escapes the gravity of the Earth in order to move further into space — for example, to the Moon or Mars or further away.
Circular Orbits:
- Satellites that orbit the Earth are mostly placed in circular orbits.
One reason is that if the satellite is used for imaging the Earth, it is easier if it has a fixed distance from the Earth.
If the distance keeps changing as in an elliptical orbit, keeping the cameras focused can become complicated.