Spacecraft propulsion is one of the key enabling technologies of the vast majority of space missions. Different mission applications and profiles require very different space propulsion systems – from high-precision small satellite thrusters for accurate pointing to large-scale vehicle boosters for deep space travel.
With such variety in demand, the spacecraft propulsion supply chain has grown and developed significantly in recent years. Many new in-space propulsion systems have been tested and proven in orbit, bringing new innovation to the market and even facilitating new mission concepts. In addition, existing systems with heritage established on larger spacecraft are being re-purposed for smaller form factor systems.
An increase in orbital traffic and the growing threat of space debris have also placed greater emphasis on the ability to avoid collisions in space, either actively or autonomously, and thrusters are often used for this.
Propulsion systems have always been a popular and dynamic area of the market, often attracting plenty of funding and media interest, and for good reason. But keeping up with the latest changes in the supply chain is a challenge.
So to help, here are some of the latest details on commercial spacecraft propulsion systems and solutions currently in use or development around the world. This page will be updated as the market evolves, so please bookmark it and check back often.
You can also stay up-to-date with the global space supply chain by signing up for our newsletter here.
First-hand, up-to-date information on commercially-available propulsion solutions:
Contents
- Understanding spacecraft propulsion
- Applications of in-space propulsion
- In-space propulsion supply chain overview
- Advice on selecting a thruster
- Assessing thruster heritage and readiness
- Resources and further reading
Understanding spacecraft propulsion
Broadly, space propulsion systems can be classified in 3 distinct categories:
- Launch vehicle propulsion – the rocket boosters and engines required to reach escape velocity and get into orbit, or beyond.
- In-space propulsion – thrusters used to manoeuvre spacecraft and satellites, re-orient space stations, provide satellite attitude control, and more.
- Re-entry propulsion – atmospheric re-entry systems, flight control propulsion, and landing boosters to land on planets or other celestial bodies.
In this resource we’re only considering the second category as spacecraft propulsion – i.e. any technology that uses propulsive systems to control its movement and orientation in space.
Such systems have a number of uses in space, as discussed in the next section.
Applications of in-space propulsion
Thrusters on satellites and other spacecraft are available in a variety of different sizes, producing thrust of varying amounts for different applications. Some of the most common uses are:
- Long-range navigation and travel – to move spacecraft to different points of interest and operational areas, such as to the Moon, other planets, asteroids, or the Sun.
- Obit raising/lowering – to move a satellite from the orbit in which it was deployed to the orbit in which will operate. Or from one operational orbit to another in more complex missions.
- Station-keeping – to maintain a specific orbit around the Earth or other celestial body, moving against the gravitational pull.
- Attitude control – to act as an attitude actuator and manage the orientation of a spacecraft or satellite so it can operate safely and effectively.
- Collision avoidance – to maneuver out of the path of oncoming space debris or space traffic and avoid a catastrophic collision.
- Meeting mission objectives – to re-orient and/or navigate to different orbits or points of interest, or to line up, deploy, and/or interact with other equipment in order to meet operational goals such as docking or in-space servicing.
- De-orbiting – to shift a system into a graveyard orbit so it can be de-orbited and burned up by the Earth’s atmosphere.
Now that we have reviewed the primary uses of spacecraft propulsion units, in orbit and beyond, next let’s take a look at the commercial market and supply chain.
In-space propulsion supply chain overview
MarketsandMarkets estimates that the global market for space propulsion was around USD 10.6 billion in 2023 and will reach USD 18.1 billion by 2028. These estimates include figures on launch vehicles, satellites, spacecraft, landers, and rovers.
Looking specifically at satellite propulsion, Kings Research estimates the market for such systems to be USD 2.31 billion in 2022, projected to reach USD 3.78 billion by 2030.
Thrusters are usually categorized in terms of propellant:
- Chemical propulsion – well-established technology that offers fast operation and high thrust.
- Electric propulsion – newer innovation offering higher total impulse but lower thrust-to-power ratios than chemical systems.
- Propellant-less propulsion – technologies such as dragsails/solar sails and tethers – only proven in small-scale demonstrations to date.
The global supply chain for spacecraft propulsion technologies is dynamic, with new systems and providers coming to market on a regular basis, and existing portfolios changing rapidly.
To view the latest information on hundreds of commercially-available systems, provided directly by suppliers themselves, take a look at the capability details on the satsearch platform at the links below:
Thruster components
While many propulsion units are available fully integrated, or can be provided with the full range of integration and operational equipment required, it is possible to acquire a wide range of other components available on the global supply chain such as:
- Propellant tanks – to protect, store, and manage delivery of propellant to the thruster.
- Propulsion system valves – that are used to control loading, drainage, and pressurization of propellants.
- Propellant – high-performing fuel for propulsion in space.
- Pressure regulators – devices that provide propellant pressure regulation and mass flow control.
- Thrust control systems – used to manage thruster operation in orbit.
In the next section we discuss some of the important factors to consider when choosing propulsion technologies for a space mission.
Advice on selecting a thruster
As the in-space propulsion market is so diverse and dynamic, you will see different suppliers describe their technology in very different ways. We’re always working to help manufacturers more clearly and consistently explain the value of what they offer, while also helping potential customers navigate the supply chain.
And so, in this section we have included a few common thruster performance criteria that should be understood and considered when sourcing a unit for a mission. Some of the nuances of certain characteristics are discussed in more detail, in places where we’ve seen some ambiguity or confusion in the market.
Common criteria:
- Specific and total impulse
- Minimum impulse bit
- Thrust range and thrust-to-power ratio
- Format – electric or chemical
- Propellant type
- Operating power
- Delta-V capability
- Operational firing time and sequences/pulses
Specific impulse and delta-V
The system you select must be able to deliver the thrust and changes in velocity needed to perform the maneuvers required in your mission. Remember that small spacecraft propulsion systems are often highly throttleable and so the impulse figures given by suppliers may not reflect the full range of performance.
Integration requirements
Plug-and-play systems can often offer lower costs, and operational and integration complexity, and the market for thruster components can also be difficult to navigate. However, there is obviously less customization available with such options.
For more information, the video below is the recording of a satsearch webinar in which a range of industry experts discuss different aspects of using thrusters in small satellite missions:
Propellant handling
Alongside the different performance characteristics of electric and chemical propulsion, you also need to factor in the safety elements of handling and storing chemical propellant. Some common chemical propellants are highly toxic and can only be handled with special safety precautions in place, which need to be factored into the engineering and operational process.
Along with these considerations, one of the most important factors in any space mission is the heritage of the hardware, which we take a look at next.
Assessing thruster heritage and readiness
As there are so many thruster providers and systems on the market, and many businesses looking to capture market share or promote innovation, it is very important to properly assess the heritage of any spacecraft propulsion unit you are interested in purchasing.
The standard Technology Readiness Level (TRL) is usually applied to thruster technologies – with most mission teams opting for hardware at TRL 9 to reduce risks and benefit from data on existing operations. However, the well-regarded industry publication State-of-the-Art of Small Spacecraft Technology report by NASA also advocates for an additional method to assess thruster readiness called Progress Toward Mission Infusion (PMI).
The report argues that the TRL system falls short when determining thruster readiness by customers as it (a) requires in-depth knowledge of the hardware which is often difficult to acquire as an external party and (b) doesn’t account for end-user applications – for example; a thruster may be TRL 9 for operation in Low Earth Orbit (LEO) but untested, and therefore at a lower TRL, for geo-synchronous orbit (GEO).
The PMI system is designed to assess the evidence of a thruster’s progress towards mission infusion. It consists of 4 categories:
- Concept (C) – systems in feasibility study phase, possibly including notional designs (TRL 1-3).
- In-Development (D) – prototypes, or fully developed systems, for which no specific mission has been publicly announced as yet and therefore they have not been fully integrated or qualified ready for use in space (TRL 4-5).
- Engineering-to-Flight (E) – devices that have a publicly announced mission or flight opportunity and is therefore undergoing (or has completed) mission-specific calibration and qualification (TRL 5-6)
- Flight-Demonstrated (F) – thrusters that have taken part in a genuine mission, or a successful technology demonstration, that has been publicly announced and described, in a target environment and appropriate platform (TRL 7-9).
In practice both the TRL and PMI scales can be used to assess the potential of an in-space propulsion solution to meet your mission goals.
Resources and further reading
- A guide to adopting thrusters on small satellite missions [webinar]
- CubeSat thrusters and small satellite propulsion systems on the global market
- The Space Engineering Resource Hub by satsearch
- Satellite components – an overview
- Attitude actuators supply chain hub
- Thruster propellant tanks on the global market
- Spotlight: De-risking the supply chain for electric propulsion systems – with ENPULSION
You can also see more information on real-world use cases of thrusters in space missions in this video from a satsearch webinar:
