Recreating vacuum of space to test propulsion systems

This firm’s one of the few in the world working on the tech behind ultra-low Earth satellites

Imagine trying to build an ion thruster that works only in the vacuum of space – the first challenge is figuring out how to test it inside a warm, air-filled laboratory. Bellatrix Aerospace solved that problem by creating machines that mimic the complete absence of an atmosphere. In its lab on the IISc (Indian Institute of Science) campus in Bengaluru, the space-tech firm now operates sophisticated systems that recreate the conditions hundreds of kilometres above Earth.

Yashas Karanam, co-founder & COO of Bellatrix Aerospace, gave us a tour of the lab. The propulsion systems that Bellatrix is making are not engines that fire rockets off the ground, they are vacuum engines, designed to work once a satellite has already been released into space. “These engines are used to reorient the spacecraft once it is in space,” Karanam explains. To test them, Bellatrix must recreate space on Earth, and that requirement has shaped almost everything the company has built here.

To recreate space, Karanam says, you need a combination of multiple pumping systems – roughing pumps, roots pumps, rotary vane pumps, turbo-molecular pumps and cryogenic pumps – working in concert to pump particles out. Finally, cryogenic plates are cooled to near absolute zero, trapping residual particles that cannot be removed by suction alone.

Extreme DIY

Bellatrix was founded in 2015 by Karanam, together with Rohan M Ganapathy and Nuthan Prasanna Kumar, all engineers with backgrounds in aerospace and satellite systems who previously worked closely with India’s space ecosystem. The company has raised over $11 million from venture capital firms, and has multiple customers, including ISRO.

What makes Bellatrix unusual is not just that it operates complex infrastructure, but that it chose to design much of it from scratch. “The machine is our own customised one,” Karanam says. Asked why, his answer is blunt: “Otherwise we could not afford it.” Some of these systems cost several crores of rupees even when built in-house. Buying them off the shelf, often from overseas suppliers, would have been prohibitive, slow and restrictive. “So we do that for a lot of things,” he says. “Even the diagnostic machines here. we could build propulsion not exist when we started. So we designed our own vacuum chambers, what allows us to work at the level of There’s a team of PhDs in the company which makes them all.”

That decision to build machines, rather than buy them, has shaped Bellatrix’s engineering culture. The company works closer to fundamental physics than most satellite manufacturers. “If you are a satellite manufacturer, you would get components which are already designed for space,” Karanam says. “We are making those fundamental elements.” That means relearning how fluids behave in vacuum and zero gravity, how electronics degas when exposed to space, and how materials degrade under radiation. “Design selection is very important. The way you configure redundancies i s very important,” he says. “It’s all together one of the most complex ways you can engineer” .

Inside one vacuum chamber, a Hall-effect thruster is mounted, tiny in size, its anode and cathode arranged to generate plasma from xenon or krypton gas. When fired, the thruster produces a plume that must be precisely characterised so that the spacecraft it is attached to can gain enough thrust to orient itself correctly. Bellatrix has built its own plasma diagnostics rigs to measure ion density, divergence angle and plume behaviour. “If the divergence angle deviates too much, your plasma turns back and falls on your satellite,” Karanam explains. That can charge the spacecraft and cause unpredictable interactions with Earth’s magnetic field.

Elsewhere in the lab, smaller vacuum chambers handle chemical propulsion systems, while degassing ovens strip moisture and contaminants from components before deeper vacuum testing. Furnaces heat-treat metals and ceramics through proprietary thermal cycles, altering material properties to survive extreme temperatures. One such process produces catalysts that can withstand combustion temperatures exceeding 1,800 degrees Celsius.

Green propulsion
Bellatrix’s work on green chemical propulsion is another area where its lab infrastructure has been critical. Traditional satellite propulsion has relied on hydrazine, a toxic, carcinogenic fuel used since the 1950s. Bellatrix developed a hydroxyl ammonium nitrate-based alternative that is safer to handle and easier to integrate. “I can touch it like this safely,” Karanam says while holding a flask of the substance. The benefit is not just environmental. Satellites can be fuelled at the manufacturing site and shipped fully integrated, rather than being fuelled at the launch site under hazardous conditions. It’s equivalent in performance to traditional propulsion fuel, but green.

Achieving that performance required thousands of iterations, balancing reactivity, stability and longterm storage. “Formulating that blend and refining it so many times to finally achieve a blend which does not react with everything, that was a major innovation,” Karanam says.

Bellatrix has also developed some of the smallest Hall thrusters in the world, including a heaterless cathode design that can be fired instantly in orbit. “Earlier, you had to turn on the heater, wait tens of minutes, and then turn on the engine,” Karanam says. “Here, this is instant. That changes the whole game.” Removing heaters also improves reliability. “Heaters are the first things to fail,” he adds. “So we have tackled the hardest problem related to failure rates.”

Beyond propulsion, the IISc lab supports Bellatrix’s longer-term ambitions, including ultra-low Earth orbit satellites operating around 200 kilometres above us. At that altitude, atmospheric drag is significant.

Maintaining orbit requires continuous thrust and extremely efficient propulsion. Bellatrix is betting that its deep understanding of propulsion physics, built through years of inhouse experimentation, will allow it to crack a problem few others have solved anywhere in the world. Engineers working on this programme draw heavily on the same vacuum, materials and diagnostics capabilities developed for propulsion, rather than relying on external suppliers.

The company is now preparing to scale. It’s already planned a large manufacturing facility on a fiveacre site near the Bengaluru airport, capable of producing hundreds of propulsion systems a year. The company recently expanded into the US, and is looking at a manufacturing facility there.