Rohini (rocket family)

For other uses, see Rohini (disambiguation).

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 (4.4 to 440.9 lb) between altitudes of 100 to 500 kilometres (62 to 311 mi). The ISRO currently uses RH-200, RH-300, RH-300 Mk-II, RH-560 Mk-II and RH-560 Mk-III rockets, which are launched from the Thumba Equatorial Rocket Launching Station (TERLS) in Thumba and the Satish Dhawan Space Center in Sriharikota. The first Rohini rocket was launched in 1963. A later series of ISRO satellites was also named Rohini (first launched 1979).

Rohini rocket family

Various programs such as Equatorial ElectroJet (EEJ), Leonid Meteor Shower (LMS), Indian Middle Atmosphere Programme (IMAP), Monsoon Experiment (MONEX), Middle Atmosphere Dynamics (MIDAS), and Sooryagrahan-2010 have been conducted using the Rohini sounding rocket series. It has been the forerunners for ISRO's heavier and more complex launch vehicles, with continued usage even today for atmospheric and meteorological research.

Nomenclature

The rockets in the series are designated with the letters RH (for "Rohini"), followed by a number corresponding to the diameter (in millimetres) of the rocket.

Series

RH-75

The RH-75, the first sounding rocket developed by India, It weighed 32 kilograms (71 lb), had a diameter of 75 millimetres (3.0 in) and flew 15 times between November 1967 and September 1968.

RH-100

The RH-100 was a single-stage solid-fuel rocket that was capable of carrying its payload up to an altitude of 55 km or more. When paired with a 650mm long by 40mm wide copper shaft dart used for meteorological research, it was referred to as a Menaka-I rocket.

RH-125

This rocket was launched on October 9, 1971, from Sriharikota. It was a two-stage rocket using a solid propellant, carrying a 7 kilograms (15 lb) payload to 19 kilometres (12 mi) in altitude. It flew twice between January 1970 and October 1971. It was used in testing and perfecting various techniques like staging, destruct system, separation devices and clustering. It was also used as a booster to the weather forecasting rockets. As such it was named as Menaka II which worked along with Menaka I.

RH-200

The RH-200 is a two-stage rocket that can reach up to a maximum altitude of 70 kilometres (43 mi). Solid motors power the first and second stages of the RH-200. A polyvinyl chloride (PVC)-based propellant had previously been employed with the RH-200 rocket. In September 2020, a new propellant based on hydroxyl-terminated polybutadiene (HTPB) was successfully used to flow it from the TERLS.

RH-300

The Rh-300 is a single stage sounding rocket, derived from French Belier rocket engine technology. It has a launch altitude of 100 km (62 mi). A variant, the RH-300 Mk-II, has a maximum launch altitude of 116 kilometres (72 mi). It has ability to lift a payload up to 80 kilograms (20 kg of scientific payload) having volume measuring 380*500 mm in diameter. It is capable of reaching very high acceleration (20 G to M6). Numerous payloads can be tested in a single flight.

RH-560

This two stage vehicle is derived from French Stromboli engine technology. Another variant, the RH-560 Mk-II, can reach a maximum launch altitude of 548 kilometres (341 mi). The RH-560 Mk-III variant's maiden flight (the flight was successful) was 12 March 2021.It achieved an apogee of 511.73 kms against the pre-flight prediction of 476 kms. The payloads were Electron and Neutral Wind Probe (ENWi), Langmuir Probe (LP), Tri Methyl Aluminium (TMA).

Applications

The RH-200 is used for meteorological studies, the RH-300 Mk-II for Middle atmospheric studies and the RH-560 Mk-II for Upper atmospheric studies and ionospheric studies. The RH-200 was used as the rocket for the first payload launch in India made by students of VIT University in Vellore.

Rohini series of sounding rockets

Name	RH 75	RH 125	RH 200/125	RH-300	RH-300 Mk II	RH-300/200/200	RH-560/300	RH-560/300 Mk II
Gross mass	8 kg (18 lb)	40 kg (88 lb)	100 kg (220 lb)	300 kg (660 lb)	500 kg (1,100 lb)	500 kg (1,100 lb)	1,300 kg (2,800 lb)	1,600 kg (3,530 lb)
Height	1.50 m (4.90 ft)	2.50 m (8.20 ft)	3.60 m (11.80 ft)	4.10 m (13.40 ft)	5.90 m (19.30 ft)	8.00 m (26.20 ft)	8.40 m (27.50 ft)	9.10 m (29.80 ft)
Diameter	0.0800 m (0.2620 ft)	0.12 m (0.39 ft)	0.20 m (0.65 ft)	0.31 m (1.01 ft)	0.31 m (1.01 ft)	0.31 m (1.01 ft)	0.56 m (1.83 ft)	0.56 m (1.83 ft)
Thrust		8.00 kN (1,798 lbf)	17.00 kN (3,821 lbf)	38.00 kN (8,542 lbf)	39.00 kN (8,767 lbf)	38.00 kN (8,542 lbf)	76.00 kN (17,085 lbf)	76.00 kN (17,085 lbf)
Apogee	10 kilometres (6.2 mi)	20 kilometres (12 mi)	80 kilometres (50 mi)	100 kilometres (62 mi)	150 kilometres (93 mi)	300 kilometres (190 mi)	400 kilometres (250 mi)	500 kilometres (310 mi)
Stages	1	1	2	1	1	3	2	2
First Launch	20 November 1967	1 January 1970	1 January 1979		8 June 1987	1 November 1985	24 April 1974	16 August 1995
Payload (kg)	1	7	10	60	70			100

Rockets based on Rohini Sounding series.

Advanced Technology Vehicle Although ALV consisted of two RH-560 motors but it was not intended for meteorological use, hence it is not regarded as a part of Rohini sounding rocket series.

Nano Satellite Launch Vehicle NSLV was initially revealed in the presentation "The Indian Space Enterprise New Vision & Direction" by S. Somanath on February 11, 2021 at Technovanza Veermata Jijabai Technological Institute (VJTI). There was a hint of "NSLV" in it. It is envisaged to put Nano Satellites into orbit. The NSLV design has the potential to become the smallest orbital rocket in use. Its engines will be adapted from several rohini sounding rocket series (RH-560) that have been in use by ISRO for years. The vehicle will have four stages, three active motors, and a top stage with a satellite-containment nose. The anticipated payload load is 5 kg (Leo: 200*2000 kms). The assembly and launch will be simple and will be used for the quick launch of micro and nano satellites. It is been built as a result of the excessive traffic on PSLV and GSLV system. NSLV will work in tandem with SSlV system. Both the SSLV and NSLV are intended to be launch-on-demand systems. No NSLV mission can be anticipated anytime soon because the first NSLV launch may take place as late as 2030.

Isbjorn-1 In 1997, the Norwegian space agency ordered a sounding rocket from the Indian Space Research Organisation (ISRO)'s commercial arm, Antrix Corporation. It was one of the earliest export orders bagged by Antrix Corporation. The mission involved launching a Rohini RH-300 Mk-II sounding rocket from Svalbard, Norway, which was shipped from India. Designed to launch a 70 kg payload to an altitude of 120 km, the RH-300 would carry a Langmuir Probe on-board, to undertake Polar Ionospheric studies. The launch was also the first from the newly setup Svalbard range, signalling its inauguration. The rocket was renamed Isbjorn-1 by the Norwegian Space Centre for the mission. ISRO faced several technical challenges while preparing for the launch in Norway. The Rohini rockets had previously operated in tropical hot and humid conditions, and the Arctic environment posed unfamiliar conditions for the team. Despite these obstacles, ISRO’s engineers successfully qualified the RH-300 Mk-II for arctic weather conditions, ensuring its suitability for the launch. Senior ISRO personnel were present to ensure the successful launch. Prior to launch, the Rocket, positioned on the launcher, was covered with a Velostat, to protect it from the harsh Polar weather, where temperatures ranged from -5 to -20 degrees Celsius. At launch it was to tear through the Velostat's fabric, soaring upwards. The Isbjorn-1 took flight at 11:07 p.m. IST on November 20, 1997, reaching, however, an altitude of only 71 km. Its range, too, fell short of the designed 129 km, by 35 km. Post-launch analysis revealed that, instead of launching the Rocket at an angle of 84 degrees, it was incorrectly aligned at 75. The velostat shroud that was used to cover the rocket to maintain the ambient temperature pulled with the rocket, instead of the rocket penetrating the velostat during launch as was intended, increasing the drag and resulting in a lower altitude. In addition, the Spin Rockets too failed to ignite, as electric supply to its igniter got disconnected, likely while covering the Rocket with the Velostat. However, there were silver linings to the outcome. The mission yielded unforeseen benefits. Due to the rocket's extended stay in the lower apogee, the payload managed to collect a substantial amount of data from that particular region.