By Rajeev Gambhir
In the realm of space exploration, sustainability, and innovation are not just ideals but necessities. The Indian Space Research Organisation (ISRO) has boldly embraced these principles with its PSLV Orbital Experimental Module (POEM). This revolutionary module redefines space utilization by transforming the ostensibly redundant PS4 stage of the Polar Satellite Launch Vehicle into a pioneering orbital platform. POEM not only exemplifies ingenuity in minimizing space debris but also unlocks new horizons for cost-effective space research. This initiative marks a significant milestone, propelling India to the forefront of sustainable space exploration and offering invaluable opportunities for industry engagement in cutting-edge space experiments.
Historically, ISRO's PSLV PS4 stage was used experimentally for short-term payloads due to its limited power generation and stability capabilities. Recognizing this, ISRO enhanced PS4 with modular subsystems, transforming it into a long-term orbital platform. Demonstrations in 2017 with PSLV-C37/C38 involved keeping PS4 operational for extended periods, and hosting payloads like IDEA (Ionization Density and Electric field Analyzer). In 2019, PSLV-C44 marked the first independent short-term operation of PS4, hosting KalamSAT-V2 by Space Kidz India. This was followed by PSLV-C45, which featured improved power capabilities with solar cells, hosting payloads like ARIS 101F and demonstrating PS4's enhanced mission life.
Transitioning from the historical use of PSLV's fourth stage, primarily as transient support for payloads, ISRO's PSLV Orbital Experimental Module (POEM) emerges as a beacon of innovation in space technology. This transformative step, where the once-discarded PS4 stage evolves into a robust microgravity test bed, marks a paradigm shift. With added subsystems for power, communication, and stabilization, POEM has transcended its traditional role, morphing into a satellite bus capable of hosting payloads for extended periods. These advancements not only extend the functional life of space assets but also open new avenues for experiments in microgravity conditions, significantly benefiting academia and start-ups by providing a low-cost, accessible platform for space exploration.
The initiative to use the PS4 stage as an orbital platform is a testament to ISRO's commitment to sustainability. Traditionally, rocket stages become inactive debris after their primary mission, contributing to the growing problem of space junk. By repurposing the PS4 stage, POEM prevents this waste and provides a valuable resource for scientific research. This approach aligns perfectly with global efforts to make space exploration more sustainable and responsible.
One of the most significant impacts of POEM has been on payload operators, particularly those from the burgeoning space industry in India. Access to space has traditionally been limited by high costs and technical challenges. POEM lowers these barriers, enabling a wide range of operators to deploy payloads in space. This access is crucial for gaining 'space heritage' – a term that refers to the proven track record of a technology's performance in the space environment. Space heritage is essential for attracting clients and investors in the competitive space technology market.
The journey of POEM is marked by several key missions, each adding to the capabilities and achievements of the platform. The PSLV-C53 mission, for instance, carried an array of innovative payloads including a Software Defined Radio-based Telemetry Multi-Media Transmitter (SDRT-MTx), a UHF Transmitter, and the OP-VIS, configured with one GVIS and two cameras. Another significant contributor, Dhruva Space, provided the Satellite Orbital Deployer (DSOD), alongside the Space Radiation Monitoring (ROBI) payload. This mission showcased the varied applications of POEM, from telecommunications to space environment monitoring.
The PSLV-C55/TeLEOS-2 mission, or POEM-2, further expanded the scope with seven experimental non-separable payloads. These included PiLOT, a cutting-edge OBC package from IIST, and ARIS-2, an ionospheric studies experiment also from IIST. Bellatrix Aerospace's HET-based ARKA200 Electric Propulsion System was a highlight, alongside deployer units and transceivers from Dhruva Space, and the Starberry Sense Payload from the Indian Institute of Astrophysics. These payloads not only demonstrated POEM's capability to support advanced scientific research but also highlighted the collaborative nature of space exploration involving multiple organizations.
The PSLV-C58/XPoSat mission brought in payloads like the Radiation Shielding Experimental Module (RSEM) from TakeMe2Space, aimed at evaluating tantalum coating effectiveness for radiation shielding. It also included the Women Engineered Satellite (WESAT) from LBS Institute of Technology for Women, and BeliefSat-0, an amateur radio satellite from K J Somaiya Institute of Technology. This mission emphasized POEM’s role in encouraging diverse participation in space research, from academic experiments to industry-driven technology demonstrations.
| Payload | Purpose | Agency/Company |
| Radiation Shielding Experiments Module (RSEM) | Evaluation of Tantalum coating effectiveness | TakeMe2Space |
| Women Engineered Satellite (WESAT) | Comparison of Solar Irradiance and UV Index | LBS Institute of Technology for Women |
| BeliefSat-0 | Amateur Radio Satellite | K J Somaiya Institute of Technology |
| Green Impulse TrAnsmitter (GIT) | Green bipropellant CubeSat propulsion unit | Inspecity Space Laboratories Pvt. Ltd. |
| Launching Expeditions for Aspiring Technologies- Technology Demonstrator (LESP-TD) | Demonstration of sub-system of microsatellite | Dhruva Space Private Ltd. |
| RUDRA 0.3 HPGP | Green Monopropellant Thruster | Bellatrix Aerospace Pvt. Ltd. |
| ARKA-200 | Heaterless Hollow Cathode for Hall thrusters | Bellatrix Aerospace |
| Dust Experiment (DEX) | Interplanetary dust count measurement | PRL, ISRO |
| Fuel cell Power System (FCPS) | Demonstration of fuel cell | VSSC, ISRO |
| Si-based High Energy cell | Demonstration of Silicon-based High Energy cells | VSSC, ISRO |
Table 1: POEM Payloads on PSLV-C58
POEM transcends mere technological triumph; it serves as a dynamic platform fostering collaboration and innovation across diverse entities. By offering opportunities to a spectrum of organizations – from startups like Bellatrix Aerospace to esteemed educational institutions like IIST and research-oriented bodies such as the Indian Institute of Astrophysics – POEM contributes significantly to nurturing a robust space ecosystem. India's space agency, ISRO, isn't just about blasting rockets into the unknown. They're also passionate about building a community around space exploration, where everyone can participate and reap the benefits. That's where the Indian National Space Promotion and Authorization Centre (IN-SPACe) comes in. Think of them as the bridge between ISRO's expertise and the dreams of private companies. By opening up access to programs like POEM, they're ensuring that the benefits of space exploration reach far and wide. It's a win-win: ISRO and IN-SPACe work together with all sorts of players, boosting India's position as a major space power on the world stage. It's collaborative, it's ambitious, and it's a giant leap forward for space exploration in India.
As POEM continues to evolve, the possibilities it opens are vast. Future missions could encompass more advanced scientific experiments, technology demonstrations, and even educational projects. This versatility makes POEM not just a platform for scientific discovery but also a catalyst for innovation in satellite technology, telecommunications, and beyond.
The success of these missions underlines the adaptability and potential of POEM, paving the way for more ambitious and varied experiments. It opens up possibilities for long-duration studies in microgravity, advanced materials testing, and space-borne technology validation, further democratizing access to space.
ISRO's POEM initiative showcases the incredible potential of creative problem-solving in tackling the hurdles of space exploration. Through this innovative approach of repurposing potential space debris into valuable scientific resources, ISRO not only emphasizes its dedication to sustainability but also opens doors to a more economically feasible and inclusive era of space exploration. With POEM's ongoing support for diverse experiments, it emerges as a pivotal force driving worldwide progress in knowledge and technological innovation on the cosmic frontier. The beautiful 'POEM' written by ISRO is much more than a series of missions; it's a narrative of India's growing prowess in space, a testament to collaboration, and a beacon of inspiration for future space endeavours.
