EL SEGUNDO, Calif. -- To ensure the resilience of orbital assets in today’s contested and congested space environment, satellites need to be able to dodge space debris, avoid potential threats, or quickly shift their position to cover a new geographic area during a crisis.
For the U.S. Space Force, ensuring our satellites can safely navigate this busy environment is a top priority. To meet this challenge, the Space Force is looking toward innovative commercial partnerships to give our smallest spacecraft a major boost in agility.
To meet this operational imperative, Space Systems Command’s System Delta 89, in partnership with Parabilis Space Technologies (or Parabilis), matured a novel application of heritage space propulsion technology, culminating in hot-fire testing to analyze and validate its performance before integrating it on an orbital testbed.
In the world of rocket science, a hot fire test serves as the moment of truth. This final, most rigorous ground-based assessment ignites and operates a propulsion system exactly as it would function during a mission in the vacuum of space.
A hot fire test is distinct from other types of testing because it involves the actual combustion of propellants. The engine is bolted to a test stand, a reinforced structure designed to hold the engine in place, while it generates thrust.
While CubeSats are cost-effective and useful for one-off experimentation and short-term Earth observation or communications missions, they generally lack any ability to move once they are in space. Enter the Dense Orbital Transfer System, or DOTS.
Developed by Parabilis, a California-based small business, DOTS is a high-performance kitchen toaster-sized hybrid rocket engine designed specifically for small cube satellites, CubeSats for short. Hybrid rockets use solid fuel and liquid oxidizer, bringing both advantages and drawbacks relative to pure solid or liquid designs.
This is where DOTS excels: it greatly improves thrust, efficiency, and mass compared to traditional hybrid rockets, all in a small, low-cost package. It also equips small satellites with a scalable, low-weight, high-impulse thrust capability, unlocking new missions that require rapid bursts of speed and agility.
Whether it's a quick sidestep to avoid a piece of space debris or a major maneuver to link up with companion satellites, DOTS gives CubeSat operators the highly-precise control they need to protect and defend space assets in a form-factor that can be hard to track.
This agility also extends to specialized missions. Some Space Force operations require satellites to fly in Very Low Earth Orbit to capture the highest quality imagery or improve communication signal strength. The Earth's thin upper atmosphere creates drag at this level, slowly pulling satellites down over time.
Beyond speed and agility, the DOTS system brings key advantages to the Space Force and the joint force. The system utilizes a "cold start" capability, meaning it doesn't require a long warm-up period before firing. This allows operators to react instantly to sudden emergencies in orbit.
Additionally, while traditional rocket fuels can be highly toxic and expensive to handle on the ground, DOTS utilizes safe-to-handle solid propellants. Solid propellant is safer for ground crews to load, easier to store for long periods, and significantly reduces the costs and delays associated with launch preparations.
“The successful hot fire of the DOTS prototype underscores the value of innovative industry partnerships that give us access to cutting-edge space technologies that directly advance U.S. space superiority objectives,” said USSF Col. Scott Klempner, Acting Space Force Portfolio Acquisition Executive Deputy for Space Combat Power.
By investing in powerful, scalable CubeSat technologies and teaming up with agile, forward-thinking small businesses, the U.S. Space Force is ensuring that even our smallest satellites have the maneuverability and resilience required to secure our nation's interests in the space domain.
Currently in the testing and development phase, the DOTS system is on track for flight-ready hardware delivery for an on-orbit demonstration no earlier than 2027.