ISRO to attempt 200th consecutively successful launch of RH-200 sounding rocket

Context

The Indian Space Research Organisation (ISRO) is going to attempt the 200^th consecutively successful launch of the Rohini RH-200 sounding rocket.

RH-200 sounding rocket:

RH-200 is a two-stage rocket capable of climbing to a height of 70 km bearing scientific payloads.
The first and second stages of RH-200 are powered by solid motors.
For years, the RH-200 rocket had used a polyvinyl chloride (PVC)-based propellant.
The first RH-200 to use a new propellant based on hydroxyl-terminated Polybutadiene (HTPB) was successfully flown from the TERLS in September 2020.
- As compared to PVC-based propellants, HTPB-based propellant is more energetic, has higher mechanical & interface properties, and has fewer defects due to lower processing temperature.
The ‘200’ in the name denotes the diameter of the rocket in mm. Other operational Rohini variants are RH-300 Mk-II and RH-560 Mk-III.

What are sounding Rockets?

Sounding rockets are one or two-stage solid propellant rockets used for probing the upper atmospheric regions and for space research.
Sounding rockets take their name from the nautical term "to sound," which means to take measurements.
They also serve as easily affordable platforms to test or prove prototypes of new components or subsystems intended for use in launch vehicles and satellites.
The first sounding rocket to be launched from Thumba was the American Nike-Apache - on November 21, 1963.
After that, two-stage rockets imported from Russia (M-100) and France (Centaure) were flown.
The ISRO launched its own version - Rohini RH-75 - in 1967.

Rohini (Rocket family)

Rohini is a series of sounding rockets developed by the Indian Space Research Organisation (ISRO) for meteorological and atmospheric study.
These sounding rockets are capable of carrying payloads of 2 to 200 kilograms between altitudes of 100 to 500 kms.

Operational sounding Rockets