Space activities in the country started during early 1960s with the scientific investigation of upper atmosphere and ionosphere over the geo magnetic equator that passes over Thumba near Thiruvananthapuram, using small sounding rockets. Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram has been pioneering the sounding rocket launch for scientific studies. Large numbers of sounding rockets have been developed and launched from Thumba Equatorial Rocket Launching Station (TERLS). ISRO has developed a series of sounding rockets called Rohini series, important among them being RH-200, RH-300 and RH-560, number in the name indicating the diameter of the rocket in mm.

1545 RH-200 rockets have been launched so far. Wednesday, July 15, 2015 became a prestigious and memorable day in the history of sounding rocket programme of India as the RH-200 rocket had its 100th consecutively successful launch from TERLS. It demonstrated the high level of quality and reliability, which have been built into this tiny rocket.

The rocket, having a diameter of 200 mm and length 3590 mm, weighs 108 kg and carries a 12 kg chaff payload. The payload gets ejected at an altitude of 70 km and scientific information pertaining to wind and wind velocity will be obtained from

70 km to 20 km. Balloon and surface MET sensors will provide data up to ground surface.

RH-200, during its flight, encounters severe environment peaks and is an ideal platform to assess new technologies, testing their airworthiness by exposing them to hostile environment. Many technologies like application of super capacitors for pyrotechnic initiation, micro centralised encoder, sequencer with solid state switches replacing costly electromechanical relays, programmable DC-DC converter, MEMS (Micro Electro Mechanical System) based angular rate sensor, etc., have been tested for survivability and air worthiness in RH-200 rockets. The development and launch of sounding rockets was a prelude to the major launch vehicles of ISRO - PSLV, GSLV and GSLV MkIII.

Many important campaigns have been t

aken up using RH-200 rockets. The most important programme was MONEX (Monsoon Experiment) under which over thousand rockets were launched. Equatorial Wave Studies (EWS) by Space Physics Laboratory had 51 launches of RH-200 rockets from SDSC SHAR. Another major programme was MIDAS (Dynamics Middle Atmosphere) by SPL, which had 180 launches of this rocket from TERLS Range.

Some of the studies aimed at using rocket borne experiments and chaff payload over Thumba are:

Middle atmospheric seasonal wind oscillations and its association with Indian summer monsoon

Features and propagation of long period, medium period and short period equatorial wave modes

Effects of long period waves on the background mean flow, gravity wave-tide-planetary wave interactions and their effects

Middle atmospheric Climatology of Thumba

Impact of monsoon circulations in stratospheric-tropospheric exchange process

The influence of Middle atmospheric circulations on the onset, strength and withdrawal of monsoon

Global analysis of the latitude-longitude variability of atmospheric oscillations (through interaction with external agencies)

Middle atmospheric variations in connection with deep tropical convection and during the stages of tropospheric low-pressure systems

Middle atmospheric variations during the polar Sudden Stratospheric Warming

Possible tele-connections among Southern Oscillation / El Nino and the equatorial middle atmosphere

Generation of gravity waves by tropospheric / stratospheric Jet streams

Rocket triggered lightning programme

Inter-annual variability of various atmospheric oscillations

Diurnal and semi-diurnal tides derivation, Quasi-Biennial Oscillation (QBO) and Stratospheric Semiannual Oscillation (SAO) effects on tides by progressive shifting of rocket launch

Payload design and development for middle atmospheric data probing

Statistical structure of wind component distribution for aerospace meteorological demands – re-entry / fragmentation analyses

The effect of climate change in the middle atmospheric regime

Dynamical effects on the seasonal variability of tropospheric-stratospheric minor constituents like ozone and water vapour in the middle atmospheric dynamics

Thousands of visitors along with the senior functionaries of VSSC witnessed this historic launch of RH-200. Director, VSSC highlighted the usefulness of sounding rockets for scientific studies.