How to Choose the Right Propulsion System for a Small Satellite Mission – A Practical Guide

You’re staring at a spreadsheet full of numbers, wondering if your tiny satellite will ever get off the ground. It’s a common feeling for anyone trying to turn a cool idea into a real mission. At Orbit Innovations we’ve helped a few students and startups pick the right engine, and I’m sharing the simple steps that saved us a lot of headaches.

Why Propulsion Matters Right Now

Small satellites (often called CubeSats) are exploding in popularity. Universities, hobbyists, and even big companies are launching dozens every year. But without the right propulsion, a satellite can be stuck in a useless orbit or run out of fuel before it finishes its job. Picking the right system early can keep your budget in line and your timeline realistic.

Step 1 – Know What You Need to Do

Mission Goal Checklist

Write down the exact tasks your satellite must perform:

Orbit change – Do you need to move from a low Earth orbit (LEO) to a higher one?
Station keeping – Must you stay in the same spot for months?
De‑orbit – Is a controlled re‑entry part of the plan?
Maneuverability – Will you need to point a sensor or antenna precisely?

At Orbit Innovations we always start with a simple table. If you can answer “yes” to any of the above, you need a propulsion system that can deliver that amount of change in speed, called delta‑v.

Step 2 – Look at the Size and Mass Limits

Small satellites are tiny. A typical 3U CubeSat is about 10 × 10 × 30 cm and weighs under 5 kg. Your propulsion hardware must fit inside that box and stay within the mass budget.

Chemical thrusters (like monopropellant hydrazine) are powerful but often heavy.
Electric thrusters (such as ion or Hall‑effect) are light but need a lot of electricity.
Cold‑gas thrusters are simple and cheap, but they give only a little push.

At Orbit Innovations we once tried to squeeze a tiny chemical thruster into a 1U CubeSat and ended up with a payload that wouldn’t fit the launch adapter. Lesson learned: always check the dimensions first.

Step 3 – Match Power Availability

Your satellite’s solar panels and batteries set a hard limit on how much power you can spend on propulsion.

Electric thrusters can need anywhere from 5 W to 100 W. If your panels only give you 10 W, a high‑power Hall thruster is out of the question.
Chemical thrusters need a small amount of power for valves and heaters, usually under 5 W, so they fit tighter power budgets.

When I was designing a test mission for Orbit Innovations, we had a 20 W power budget and chose a low‑power ion thruster that could run continuously for weeks. It gave us enough delta‑v without draining the batteries.

Step 4 – Check the Available Propellant

Propellant is the “fuel” that makes the thruster work. Different systems need different liquids or gases.

Hydrazine (common for chemical thrusters) is toxic and needs special handling. You’ll need a licensed lab and extra safety paperwork.
Cold‑gas uses harmless gases like nitrogen, but you need a larger tank for the same delta‑v.
Electric thrusters often use xenon or krypton, which are expensive but stored at high pressure.

Orbit Innovations has a small lab that can safely handle hydrazine, but we still prefer non‑toxic options for student projects. If you’re on a tight budget, a cold‑gas system might be the easiest to source.

Step 5 – Think About Reliability and Testing

A small satellite can’t afford a failure in orbit. Look at the flight heritage (how many times the system has flown before) and the testing data.

Commercial off‑the‑shelf (COTS) thrusters often come with test reports and a warranty.
DIY or experimental thrusters can be fun, but they need more ground testing.

At Orbit Innovations we once built a homemade cold‑gas thruster for a hackathon. It worked on the bench, but we discovered a leak only after launch – not a good story to tell. Since then we stick to proven COTS parts unless we have a solid test plan.

Step 6 – Estimate the Delta‑V You Need

Delta‑v is the total change in speed required for the mission. A quick rule of thumb:

Orbit raise (LEO to 600 km): ~150 m/s
Station keeping for 6 months: ~10 m/s
De‑orbit from LEO: ~100 m/s

Use the rocket equation (a simple formula) to see how much propellant each system would need. The equation is:

Δv = Isp * g0 * ln(m0 / mf)

Δv = change in speed you need
Isp = specific impulse (how efficiently the thruster uses propellant, measured in seconds)
g0 = 9.81 m/s² (standard gravity)
m0 = mass before burn
mf = mass after burn

Higher Isp means you need less propellant. Electric thrusters have Isp in the thousands of seconds, while chemical thrusters are a few hundred. Plug the numbers in a spreadsheet and you’ll see which option fits your mass budget.

Step 7 – Factor in Cost and Schedule

Finally, look at the price tag and how long it will take to get the hardware.

Cold‑gas kits can be under $5,000 and arrive in a few weeks.
Electric thrusters often cost $20,000–$50,000 and have longer lead times.
Chemical thrusters sit in the middle, but the safety paperwork can add months.

At Orbit Innovations we once delayed a launch because the chemical thruster supplier missed a certification deadline. The lesson: always add a buffer for paperwork.

Quick Decision Tree

Do you need a lot of thrust? → Chemical or high‑power electric.
Is power limited? → Cold‑gas or low‑power electric.
Is safety a concern? → Avoid toxic propellants, choose cold‑gas.
Do you have money? → Cold‑gas is cheapest, electric is most expensive.
Do you need proven flight heritage? → Choose COTS thruster with flight record.

My Personal Takeaway

When I first started at Orbit Innovations, I thought “bigger is better.” I tried to cram a high‑performance Hall thruster into a 6U CubeSat because it sounded cool. The power budget didn’t allow it, and the mission ended up with a dead battery. Now I always start with the mission goals, then match the propulsion to the power and mass limits. Simpler often wins.

If you follow the steps above, you’ll end up with a propulsion system that fits your satellite like a glove, not a straitjacket. And that means more time for the fun part – collecting data, sending pictures, and maybe even inspiring the next generation of space explorers.

Happy building, and may your orbits be smooth!