ISRO gearing up for 200th sounding rocket Rohini launch

Insight Online News

Chennai, Sep 27 : As part of celebrating the World Space Week from
October 4 to 10, the Indian Space Research Organisation (ISRO) will
accomplish a remarkable feat – the 200th consecutive successful launch
of the Rohini RH-200 sounding rocket in 4-5 weeks’s time.
According to the Vikram Sarabhai Space Centre (VSSC), Thumba, near
Thiruvananthapuram, the 3.5-meter-tall RH-200, a trusted member of the
Rohini sounding rocket family used by the ISRO for atmospheric studies,
has completed 198 consecutive successful flights.
The launch of 199th flight of Rohini-RH will take place on October seven
and the 200th milestone will be by the end of October or early November,
ISRO said.
Sounding rockets have an important place in the ISRO story.
The first sounding rocket to be launched from Thumba was the American
Nike-Apache on Novewmber 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. The sounding
rocket programme ‘‘was indeed the bedrockon which the edifice of launch
vehicle technology was built”, ISRO noted.
Sounding rockets are one or two stage solid propellant rockets used for
probing the upper atmospheric regions and for space research.
Sounding in the rocket context is equivalent to “taking a measurement”.
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.
With the establishment of the Thumba Equatorial Rocket Launching Station
(TERLS) in 1963 at Thumba (a location close to the magnetic equator), there
was a quantum jump in the scope for aeronomy and atmospheric sciences
in India.
The launch of the first sounding rocket (American Nike-Apache) from Thumba
in 1963, marked the beginning of the Indian Space Programme. After that, two
stage rockets imported from Russia (M-100) and France (Centaure) were flown.
ISRO started launching indigenously made sounding rockets from 1965 and
experience gained was of immense value in the mastering of solid propellant
In 1975, all sounding rocket activities were consolidated under the Rohini
Sounding Rocket (RSR) Programme.
Rohini is a series of sounding rockets developed by the ISRO for meteorological
and atmospheric study. These sounding rockets are capable of carrying payloads
of two to 200 kgs between altitudes of 100 to 500 kms.
RH-75 (with a diameter of 75mm) was the first truly Indian sounding rocket, which
was followed by RH-100 and RH-125 rockets.
The ISRO currently uses RH-200, RH-300 Mk-II and RH-560 Mk-II rockets, which were
launched from the TERLS and the Satish Dhawan Space Center in Sriharikota, Andhra
The sounding rocket program served as the foundation for ISRO’s launch vehicle
RH-200 (the ‘200’ in the name refers to the rocket’s diameter in mm) is a two-stage
rocket capable of reaching a height of 70 kms while carrying scientific payloads. The
first and second stages of RH-200 are powered by solid motors.
So far, the ISRO has launched over 1,600 RH-200 rockets. On July 15, 2015, the
rocket completed its 100th consecutive successful mission.
The rocket has served as a versatile platform for experiments and the testing of new
technologies over the years.
For many years, the RH-200 rocket used a propellant made of Polyvinyl Chloride (PVC).
In September 2020, the first RH-200 with a new propellant based on hydroxyl-terminated Polybutadiene (HTPB) was flown successfully from the TERLS.
“The 199th launch (from Thumba) will happen on October 7 during the World Space Week celebrations. The 200th will take place either towards the end of October or the beginning
of November”, ISRO said.
Sounding rockets play a significant role in the ISRO story. ISRO was taking baby steps in
rocketry when the RH-200 was first introduced. In addition to atmospheric studies, there
was a focus on aspects such as spin stabilisation and solid motors. Since then, sounding
rockets have been used in a variety of experiments, including those investigating eclipse


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