Beyond Toxicity

The Second Burn

Missed the first burn? We’re unpacking a major turn in space travel, moving away from hydrazine’s hazardous grip toward a green revolution. Last time, in Beyond Toxicity - From Hydrazine to Green, we broke down hydrazine’s legacy, its high-stakes challenges, and the urgent drive for sustainable options.

In the vast expanse of space, a quiet revolution is underway. Beyond the familiar roars and the toxic haze of traditional propellants, a new era of green propulsion emerges, promising a cleaner, safer journey beyond Earth's atmosphere. At the forefront of this revolution are HAN-based blends, offering a glimpse into a sustainable future that outshines its predecessors, as well as it’s contemporary “greens”.

In 2019, a small spacecraft hummed to life 720 kilometers above Earth, its thruster firing with a cleaner, quieter promise. That was NASA’s Green Propellant Infusion Mission (GPIM), clocking ~11,400+ hours in orbit and marking a turning point in aerospace technology.

Thrust with Trust

Imagine satellites navigating the vastness of space, their every move driven by propulsion systems: the critical engines behind modern space exploration. These systems do more than launch; they power a range of precise maneuvers. They boost satellites into higher orbits, ensuring missions reach their intended heights. They provide steady thrusts to maintain position, keeping satellites on task. In satellite constellations, propulsion handles phasing, aligning each unit for seamless coordination. When space debris threatens, these systems enable collision avoidance, swiftly adjusting paths to protect valuable assets. Or at a mission’s end, safely removing satellites from orbit. Propulsion isn’t just about raw power; it’s the backbone of control and success in space.

Among these systems, chemical propulsion is the veteran of space mobility reliable, straightforward, and packing a punch. It’s all about combustion: mix a propellant with a catalyst/oxidizer, light it up in a chamber, and let the high-pressure gases rip through a nozzle engineered to channel that raw power into thrust. Whether it’s 1 Newton for a tiny satellite or hundreds for a hulking satellite; chemical systems deliver with specific impulse (how far your thruster can cruise on a single sip of propellant) ranging 160–350 seconds.

But the real story starts when you put it to work and see where it shines or stumbles. Picture a 500 kg satellite needing a precise velocity boost, or ΔV. A chemical setup running on hydrazine might chew through 50-80 kg volume of propellant to get the job done. Whereas, if you swap that with a HAN-based system—more efficient by up to 30%, and you’re looking at just 35-40 kg of fuel for the same maneuver. Less mass, longer missions, and more room for payloads instead of propellant.

Now zoom in on a small satellite, scraping by on a 300–500-watt power budget. Hydrazine may burn hot, but it freezes at a chilly -2°C; so unless you fancy your fuel as an orbital ice cube, you're forced to run line-heaters 24/7. They quietly sip off 2–5 watts, nibbling away at precious power: about 1% of the satellite’s entire energy budget, just to keep the juice flowing. If you consider BHM-01A [Bellatrix; HAN-based blend]: more efficient, with a freezing point plunging to -40°C or even -60°C. No heaters, no power drain: just a smart, lean fuel that’s ready to roll. This isn’t just about thrift; it’s about opening the door to longer missions where every watt and gram counts.

A Tale of Greens

The quest for greener space travel has birthed many players: HAN-based blend, Hydrogen Peroxide-based blend (H₂O₂), Nitrous Oxide-based blend (N₂O), and ADN-based blend. Each has its roots, its journey, and its limits.

  1. The old green guard, H₂O₂-based blend, with its simple decomposition into water and oxygen. It’s “green” in theory with no toxic fumes, but its quirks kept it niche. Freezing at -11°C, decomposing unpredictably, and demanding ultrapure tanks, H₂O₂ never scaled to rival hydrazine’s dominance.


  2. The wildcard, N₂O-based blend, a bipropellant, laughing its way up, blending with fuels like propylene (C3H6). Self-pressurizing and non-toxic, it’s a handling dream. Though its specific impulse is a attraction but to get that you’ll have to carry a whole lot of extra baggage too.


  3. Next we have Ammonium Dinitramide (ADN), a relatively mature green alternative, adopted across parts of the European Union. ADN-based propellants like LMP-103S offer improved safety and decent performance compared to legacy options. While ADN systems have seen success in specific missions, they still face challenges.


  4. Imagine a satellite being fueled right on the manufacturing floor, then safely shipped, fully loaded, no hazmat suits, no drama. That’s the promise of Hydroxylammonium Nitrate (HAN), flipping the script on traditional propellants. HAN-based blends like BHM-01A from Bellatrix Aerospace are stepping up with serious credentials, poised to take hydrazine’s throne. With a specific impulse reaching up to 250 seconds, HAN delivers more thrust per drop, giving satellites the range to push deeper into space: cleaner, safer, and smarter.

Thrust (Face) OFF

Imagine a high-stakes expedition to the Moon, where green propellants rev their engines for the top spot. Let's line them up and determine who takes the win:

More Bang, Less Bulk

In space, efficiency isn’t optional, it’s everything. Specific impulse (Isp) is the gold standard, measuring how long a propellant can produce thrust per unit of mass. Bellatrix’s HAN-based BHM-01A clocks in at a solid 240-260 seconds, outpacing H₂O₂’s modest 160 seconds (even at 98% purity) and rivaling N₂O’s 250-270 seconds, though N₂O needs the baggage of dual tanks and extra plumbing to get there. HAN, on the other hand, keeps it simple and smart. Think of it as packing a week’s worth into a carry-on, while the others show up with check-in chaos.

HAN boasts a density from 1.4 to 1.8 g/cm³, enabling it to pack more propellant into the same tank space compared to N₂O and H₂O₂, whose efficiencies dip when diluted. This higher density translates into a more compact and powerful system.

No Drama & No Fuzz

Though H₂O₂ might seem innocent, it’s a sly one—releasing oxygen vapors that flirt with danger, demanding tight ventilation, and needing external systems just to stay stable due to its low vapor pressure, which adds weight. NASA learned this during Project Mercury (1961–1963), where ~90% H₂O₂ powered attitude control thrusters, but its short shelf life and reactivity forced mission caps at just a few orbits. Engineers feared it would degrade mid-flight, risking loss of control. With HAN, we leave those worries behind—non-toxic, thermally stable, and mission-ready.

The Long Game

Precision is life for satellites. HAN thrusters, like Bellatrix’s Rudra (1 N), pulse in under 20 seconds for constellation tweaks or junk de-orbiting. H₂O₂ and N₂O-based blends can’t keep pace with HAN’s snappy reignition. This nimbleness in reignition and operation gives it an edge in deep-space missions, where flexibility and reliability are paramount. In today’s space travel’s story, HAN doesn’t just tweak the old ways, it has pivoted the entire conversation. It’s smart and safe, powering satellites and dreams with a bright trail for the future.

Pioneering the Green Frontier

At Bellatrix Aerospace, our commitment to pioneering the green frontier is unwavering. Our fully in-house development strategy, from thruster design to propellant formulation, not only fuels rapid innovation but also ensures that our solutions meet the exacting demands of space missions. It’s about rewriting the playbook for a sustainable space future. We’re pushing the boundaries, propelling dreams into orbits and beyond.

Join us as we continue this journey. In our next blog, we will dive deep into the sub-systems of green propulsion. We'll explore how these advanced technologies are not only shaping the future of aerospace but also proving to be a smart investment in our collective future.

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Email: info@bellatrix.aero