The Zenno Drive - Credit Zenno Astronautics

Green propulsion systems for satellites is the current leading edge of space technology. With huge increases in satellite deployments, finding ways to keep satellites in space longer, for less money and with a smaller environmental impact is something many companies are researching.  

New Zealand based company, Zenno Astronautics (founded by Max Arshavsky, a University of Auckland alumni) are no exception. The start-up, which has been awarded a number of grants to help develop their technology, are hoping to create a propulsion system that requires no fuel of any kind. 

“Our system is fully green, No propellant of any kind. Here's the thing, when we think about propulsion or in general you know, control of a satellite in space it requires some kind of force,” said Founder and CEO of Zenno, Max Arshavsky. 

“And how do we produce force historically? Well, we have an energy source, which is typically in space we acquire energy from the sun and then we have some kind of a propellant that actually produces force. But there is actually a smarter way to do it, which has recently become feasible.” 

"[We] simply develop a magnetic field and use that magnetic field to push against another field. That could be the field of earth or field of something nearby, [such as a] satellite,” he continued. 

The company which was founded in 2017, has received a number of grants to develop this technology. In 2018, Zenno entered and went on win the $100,000 Challenge run byVelocity, the University of Auckland’s student-led entrepreneurship development programme, winning a $25,000 grant and a spot in CIE’sVentureLab incubator programme. 

The company has then gone on to receive further seed funding through a number of funding rounds, totalling over $1 Million (NZD). Zenno Astronautics sits in prestigious company, with them being supported by Outset Ventures, who also have Rocket Lab in their family of enterprises.

This stereoscopic visualization shows a simple model of the Earth's magnetic field. The magnetic field partially shields the Earth from harmful charged particles emanating from the sun. The field is stretched back away from the Sun by solar particles and radiation pressures. Credit - NASA

According to Arshavsky, the design is beautiful in its simplicity, requiring no polluting chemicals such as hydrazine and has the potential to never run out. 

“My [view of things] historically is to look for something that is to look for the most stable, the most simplistic solution there is, stability and a simple approach guarantees that it will be a good long-lasting, trouble-free solution,” he said

However, using magnetic fields is not as straightforward as it may seem. Whilst it has been studied in some depth, the Earth’s magnetosphere, the region of space surrounding the Earth which experiences magnetic influences driven by Earth’s internal dynamo, is not uniform and can be impacted by strong solar storms. 

A team at NASA is monitoring and mapping Earth’s magnetic field to understand the impacts changes have on our near-space environment. This region of space contains many critical service satellites used by billions of people and is slowly also growing a greater human presence, such as astronauts located on the Space Station. 

Arshavsky compared this environment to that of sailing when discussing how the system would work with these dynamic fields. 

“It is based upon understanding our own field, the one that we would generate, without understanding at least one field it would be very difficult to do any kind of control.”

“Essentially the analogy that I have is if you understand your own sail and your own yacht you can get away with not having a precise understanding of the state of the winds around you. You can respond in real-time to the changes in the winds provided you have an objective in mind,” he said.

There have also been some challenges in developing the technology according to Arshavsky. 

“New technology that has become available recently essentially allows you to achieve very high magnetic field densities, huge magnetic dipole moments at almost no cost.” 

“The problem has been essentially to do with managing the superconductors in space, but we've cracked that, we've tested that, patented that so we're now very excited about the applications,” he said. 

Earlier this year, Zenno submitted a patent application to the New Zealand Intellectual Property Office for a novel cooling system for a superconducting electromagnet. The patent document suggests that the new propulsion system will be used in 1-3 U CubeSats and will use the direct interaction of the satellite's magnetic field and a non-uniform external magnetic field. 

The potential of the system is impressive, with the flexibility of it being a major consideration. 

“The system itself is not dependent on the origin of energy, it merely is dependent on energy,” said Arshavsky. “If you've got a long life energy source, it will just keep going on forever for as long as that's available.”

In almost 60 years of space activities, more than 5200 launches have placed some 7500 satellites into orbit, of which about 4300 remain in space. Only a small fraction − about 1200 – remain operational. This large amount of space hardware has a total mass of more than 7500 tonnes. Credit - ESA

With more satellites being launched, it is no secret that the space directly around Earth is getting crowded. Companies are looking at ways to extend the life of their satellites, make them more maneuverable as well as looking at ways to reduce their environmental impact.   

Companies such as Queensland based Valiant Aerospace and Hypersonix are looking to do that with green fuels, however, they still require a fuel that limits how long a satellite can stay operational. Maneuvering satellites to avoid collisions eats into these precious fuel reserves and is usually only done as a last resort, as such maneuvers can limit the satellites service life. A limitless propulsion system would have a huge impact on satellite usability. 

“When I look at companies struggling these days with having to refuel themselves in space and having to deal with the propellants that are dangerous and polluting the atmosphere, or having to deal with the constraints of running out of fuel and having to weigh up the options whether to do a maneuver to avoid the debris or whether to take the risk to prolong the lifetime, you know it is not good because it is not the most stable solution. So, if we can achieve this, it would be a beautiful thing for the space industry,” said Arshavsky

“[We want to] make satellites much more agile than they are at present. We rely on fuel-free safe clean electromagnetic engines and we [have entered] the market through the point of formation flight, safe rendezvous and docking. Our long-term vision is orbit keeping for satellites in low earth orbit as well as large-scale assembly in orbit,” said Arshavsky

Arshavsky also hopes that by extending the life of satellites, not only will there be fewer satellites required, it will also reduce the number of launches needed, helping to also reduce the environmental impact. 

The “shoe-box” sized drive also has the potential to help satellites fly in formation, something UNSW Space are hoping to demonstrate, using more traditional techniques, with their M2 satellite they launched earlier this year. 

Zenno hopes to have its propulsion system onboard a satellite in the next 18-24 months.    

“We have a beautiful team, all of us will love it every day. You know we enjoy being there and we enjoy building this. It's an amazing journey. I'm not really too keen on speeding it up too much, it's a lot of fun,” Arshavsky said of the journey so far. 

“Our ultimate aim at Zenno is to build an electro-magnetic acceleration tunnel that would allow for interplanetary spacecraft transfer and orbital acceleration. Why? Because I’m curious. I want to know – what’s beyond the pale blue dot?,” concluded Arshavsky.