Rehbar (rocket family)
The Rehbar rocket family consists of a series of sounding rockets developed by Pakistan's Space and Upper Atmosphere Research Commission (SUPARCO) in the 1960s for scientific research into the upper atmosphere.[1] The program began with Rehbar-I, a two-stage solid-fuel sounding rocket launched in 1962 from Sonmiani Beach in Balochistan, in collaboration with NASA, which carried an 80-pound sodium payload to an altitude of 130 km to study wind conditions and other atmospheric properties.[1][2] This launch positioned Pakistan as the third country in Asia—after Japan and Israel—and the tenth worldwide to successfully send a rocket into space.[1][2] Key subsequent variants included the Shahpar, a 7-meter-long two-stage solid-fuel rocket designed to carry a 70 kg payload to altitudes of up to 950 km, and the Rukhnum (also spelled Rukhnuma), a three-stage liquid-fuel rocket capable of reaching 1,000 km with a 38–50 kg payload for investigating weather patterns, cloud formation, cyclones, and space phenomena over the Arabian Sea.[1][3] These indigenously produced rockets, supported by international partnerships including NASA, represented SUPARCO's early advancements in rocketry and marked the establishment of Pakistan's first rocket manufacturing facility in Karachi by 1967.[2][4] The Rehbar family laid the groundwork for Pakistan's broader space program, facilitating suborbital missions from 1962 until 1972 before the focus shifted toward satellite development in the 1970s and beyond.[1][4]Overview and History
Program Origins and Development
The Space and Upper Atmosphere Research Commission (SUPARCO) was established on September 16, 1961, as a committee under the Pakistan Atomic Energy Commission (PAEC), which had been formed in 1956 as part of the U.S.-led Atoms for Peace initiative to promote peaceful nuclear and scientific research.[5][6] Initially focused on upper atmosphere research, SUPARCO aimed to advance Pakistan's capabilities in space sciences amid the global space race sparked by the Soviet Union's Sputnik-1 launch in 1957.[5] This formation reflected Pakistan's post-independence drive, just 14 years after gaining sovereignty in 1947, to build indigenous scientific infrastructure and contribute to international efforts in atmospheric and ionospheric studies.[1] In late 1961, SUPARCO decided to prioritize the development of sounding rockets to probe the upper atmosphere, driven by national ambitions to achieve technological self-reliance and participate in global scientific endeavors.[7] This initiative was spearheaded by Nobel laureate Dr. Abdus Salam, who served as the commission's first chairman and envisioned a program that would gather data on atmospheric conditions, cosmic rays, and ionospheric behavior to support broader meteorological and communication research.[1] The decision aligned with Pakistan's strategic goals during President Ayub Khan's era, emphasizing scientific progress as a marker of national development in a geopolitically volatile region.[1] To enable these efforts, SUPARCO established the Sonmiani Rocket Range—later known as the Sonmiani Flight Test Range—in 1961 as its primary launch site, located along the Arabian Sea coast in Balochistan province, approximately 50 kilometers west of Karachi.[8] The facility was set up on a coastal military site to facilitate over-water trajectories for safety and telemetry recovery, featuring basic infrastructure such as launch pads, tracking stations, and assembly areas constructed with rapid support from local and international partners.[6] This strategic location provided ideal conditions for suborbital flights, allowing payloads to reach altitudes up to several hundred kilometers while minimizing risks to populated areas.[8] From its inception, SUPARCO received initial U.S. assistance through NASA, which began providing technical expertise, training for Pakistani scientists, and components for sounding rockets in 1961 to foster international collaboration in upper atmosphere research.[7] This support included guidance on rocket assembly, instrumentation, and launch procedures, enabling SUPARCO to transition from theoretical studies to practical experimentation without starting from scratch.[1] The partnership underscored the era's emphasis on sharing space technology for peaceful purposes, positioning Pakistan as an early participant in global sounding rocket programs.[7]Early Milestones and International Collaboration
The Rehbar-I rocket marked Pakistan's entry into space exploration when it was successfully launched on June 7, 1962, from the Sonmiani Beach rocket range in Balochistan.[9] This two-stage solid-fuel sounding rocket, based on the American Nike-Cajun design, carried a payload of 80 pounds of sodium vapor to an altitude of approximately 130 km, enabling the study of upper atmospheric winds and cosmic radiation.[10] The launch, conducted by the newly formed Space and Upper Atmosphere Research Commission (SUPARCO), positioned Pakistan as the third country in Asia and the tenth globally to achieve such a feat.[11] Just two days later, on June 9, 1962, Rehbar-II followed as the second launch in the series, incorporating refinements from the initial mission to enhance data accuracy on atmospheric layers.[12] This rocket also utilized a Nike-Cajun configuration but featured improved instrumentation for measuring wind shear and velocity structures, building directly on Rehbar-I's success to validate and expand the collected observations.[13] These back-to-back launches demonstrated rapid progress in Pakistan's nascent rocketry capabilities. The early Rehbar milestones were bolstered by close international partnerships, particularly with NASA and the U.S. Army, which provided technical expertise, rocket components, and training for Pakistani engineers.[1] From 1961 to 1962, a team of SUPARCO personnel received specialized instruction at U.S. facilities, including Wallops Island and Goddard Space Flight Center, facilitating the assembly and operation of the Nike-Cajun systems.[14] This collaboration was pivotal in enabling the swift execution of the 1962 launches. Between 1962 and 1972, the Rehbar program expanded significantly, with SUPARCO conducting around 200 sounding rocket flights in total, advancing upper atmospheric research.[11] However, the program concluded in 1972, as national priorities shifted toward satellite development and broader space applications, marking the end of the focused sounding rocket era.[1]Design and Technology
Rocket Configuration and Components
Early variants of the Rehbar rocket family, such as Rehbar-I, utilized a two-stage solid-fuel configuration adapted from the American Nike-Cajun sounding rocket design, which was transferred through international collaboration with NASA. The first stage employed a Nike booster motor (designated M5-E1), a solid-propellant unit that provided the initial high-thrust acceleration, while the second stage incorporated a Cajun motor (TE-82 Mod2), also solid-fueled, ignited via a pyrotechnic delay following booster burnout to extend the trajectory into the upper atmosphere. Both stages featured four canted fins in a cruciform arrangement for spin stabilization, ensuring aerodynamic control without active steering mechanisms.[15][16][17] The airframe was constructed using lightweight metals suited for high-altitude flight, including steel for the Nike booster body and stainless steel for the Cajun upper stage, with extruded aluminum employed for the fins and structural adapters to balance strength and weight reduction. Overall dimensions adhered to the standard Nike-Cajun profile, with a total height of 7.70 m—including the payload section—and a uniform diameter of 42 cm across the stages, facilitating compatibility with launch rails and payload integration. The booster measured approximately 4.04 m in length, while the upper stage extended about 1.94 m, allowing for a compact assembly optimized for suborbital missions.[16][17][18] Guidance and control were rudimentary, relying on passive spin stabilization imparted by the canted fins rather than advanced inertial systems, with radio-based telemetry links (such as FM/FM at frequencies like 240.2 MHz) for real-time data transmission during flight. Stage separation occurred automatically via the timed pyrotechnic igniter, without radio command intervention, ensuring reliable progression from booster to sustainer phase. Tracking support included Doppler velocity and position (DOVAP) transponders operating at 73.6 MHz to monitor the vehicle's path from ground stations.[15][19] Payload integration centered on a modular nose cone section, typically 58-80 cm long and constructed from fiberglass or compatible composites to protect instruments from aerodynamic loads and thermal stresses. This forward compartment accommodated scientific payloads weighing 8-43 kg, secured with mounting rails and shock-isolated bays, while separation mechanisms—such as pyrotechnic bolts or spring-loaded ejectors—enabled post-apogee deployment for parachute recovery and data retrieval. Telemetry antennas and power supplies were embedded within the cone to maintain instrument functionality throughout the flight profile.[15] By 1967, Pakistan had established its first rocket manufacturing facility in Karachi, enabling indigenous production of these early Rehbar variants with support from international partnerships.[2]Specifications and Performance
The Rehbar rocket family consisted of two-stage solid-propellant sounding rockets, primarily utilizing the Nike booster as the first stage and the Cajun motor as the second stage in early variants like Rehbar-I. The Nike stage generated a nominal thrust of 209 kN (47,000 lbf) with a burn time of 3.5 seconds, providing initial acceleration for liftoff and ascent. The Cajun stage followed, delivering approximately 36 kN (8,100 lbf) of thrust over a burn time of 4 seconds to extend the trajectory into the upper atmosphere.[20][21][22][15] Launch masses for the early Rehbar variants were around 698 kg, enabling the carriage of scientific payloads typically ranging from 23 to 36 kg, such as the 36 kg (80 pounds) sodium vapor payload in Rehbar-I. These configurations allowed for suborbital flights focused on atmospheric research, with the overall vehicle length measuring about 7.7 m and a diameter of 0.42 m.[23][11][24]| Parameter | Nike Stage (First) | Cajun Stage (Second) |
|---|---|---|
| Thrust | 209 kN | 36 kN |
| Burn Time | 3.5 s | 4 s |
| Propellant Type | Solid | Solid |