Industry Roundtable

Attention: open in a new window.

MSMF asked industry officials to respond to the following question:

The Department of Defense, through programs such as Operation Responsive Space, wants smaller satellites built, modular in design, which can be rapidly configured to meet immediate mission requirements. That program requires the development of smaller propulsion systems that can be integrated into a modular design. Please describe your company’s projects that are working toward that goal.

RESPONSIVE SPACE PROPULSION
TECHNOLOGY SPACE DEVELOPMENT AT AEROJET

by Farid M. Khadduri
Vice President
Engineering and Technology
Aerojet
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Aerojet, a recognized leader in developing and producing rocket propulsions systems serving DoD and space markets, is actively pursuing technologies in support of Operationally Responsive Space requirements. ORS and similar initiatives place a premium on the ease of logistics and flexibility of design all done at the lowest possible cost. The resulting technologies focus on smaller, modular propulsion systems using low-cost components that can be rapidly integrated or re-configured to meet mission objectives.

Significant advancements have been made at Aerojet through external and internal investment to successfully reduce the cost, size, power and mass of various propulsion system components. In addition, Aerojet has developed propulsion elements that utilize alternate propellants with greatly reduced toxicity. Aerojet is leveraging these advancements and applying the technologies to small spacecraft propulsion systems.

Aerojet is in the process of refining and optimizing a variety of propulsion system architectures that employ these technologies for a range of applications from small, several-kilogram CubeSats to miniature propulsion systems for much larger spacecraft. The various architectures are designed to be compatible with a range of propellants, including cold gas and condensable gas for small satellite applications requiring low total impulse to miniature, high-performance, low-cost monopropellant systems for larger spacecraft requiring increased total impulse.

Aerojet has successfully demonstrated a suite of miniature thruster technologies derived from our missile defense produce line that provide a tenfold decrease in thruster mass as compared to traditional spacecraft thruster technologies. Similar mass reductions have been demonstrated for related system components, including propellant tanks, valves and regulators. Miniature fast response thruster valves have been demonstrated that satisfy the demanding performance necessary to achieve fine pointing control for even the smallest spacecraft currently envisioned while at the same time providing the control authority required for much larger spacecraft in the several hundred kilogram class.

In addition to these small satellite propulsion efforts, Aerojet is also leveraging its broader propulsion and space electronics expertise in support of responsive space. Studies are ongoing in the areas of high-efficiency, high-reliability spacecraft power management and distribution electronics, as well as in low-cost space access concept development. ♦

NEW MINIATURIZED PROPULSION SYSTEM
AT DIGITAL SOLID STATE PROPULSION

by Wayne N. Sawka, Ph.D.
President
Digital Solid State
Propulsion LLC
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Ever since Professor Bob Twiggs from Stanford University introduced me to the CubeSat platform in 2001, I’ve had new miniaturized propulsion systems in mind. At that time, I was just starting to work with the first highperformance electric solid propellants, but knew immediately these would be perfect for small satellite applications. However, acceptance of CubeSat usefulness and market growth has been rather slower than we all had envisioned. Hopefully, programs like Operationally Responsive Space can help the small satellite market become a vital part of future space activities.

The extinguishment and throttling characteristics of our electric solid propellants allows us to simply produce tiny—4 x 12 mm—solid-state, micro-thrusters that controllably provide tens of mNsec thrust, on-demand. Not including the electrical power supply/controller, we’re using a total of just five or six parts for a micro-thruster; that’s it. This simplicity and compactness also lends itself to both low cost and hard applications like tether and solar sail deployment. Depending on need, the same basic microthruster can be pulsed several hundred times for a few milliseconds to conduct proximity operations or fired just once for a couple-seconds duration, allowing a delta-V adjustment. For higher thrusts, additional electrical power can be used to provide a greater-than-10-times throttle-up. Otherwise, clusters of several micro-thrusters electrically self-balance and provide simultaneous ignition; extinguishment. For larger spacecraft, such clusters would provide an inherent level of redundancy to the propulsion system.

Our current challenge is to provide the Navy with propulsion options for future longrange projectiles, which will need to be re-oriented during short exo-atmospheric transits. Though similar in size to small satellites, a projectile has the added complication of the extreme G-loading from gun launch, so we are working on new designs now. Recently, we’ve made great progress with our thrust accuracy and reproducibility and learned a lot about different ignition modes. We have also spent a lot of time developing small versatile power supplies. Now rather than demonstrating our thruster firings with a large power supply plugged into the wall, we use a tiny electronics board with just a couple of AA batteries. ♦