TECHNOLOGY

PROBLEM IN SPACE DEVELOPMENT

With the rapid development of private space companies, and the miniaturization of space satellites, ridesharing to space - i.e. launching multiple satellites into the same orbit using a single rocket - has become the most common way to send satellites into space. Ridesharing has the advantages of increased launch opportunities and reduced launch costs, however, there are no safe and high thrust propulsion systems that rideshare satellite can use to travel the “last mile” to more desirable orbits. Most small satellites remain stuck in the rideshare orbit, and space developers are limited to a narrow range of orbits.

Small Satellites

Payload Fairing

Main Satellite

Propulsion Devices(Kick Motor)

Image of Satellites Ridesharing

Trade-offs in Propulsion Systems

Safe

While these propulsion systems are relatively safe, they take a much longer time to travel, because they produce only about 1/100,000 of the propulsive power of liquid fuel. Also, their slow speeds lead to other challenges, such as prolonged exposure to Earth's radiation belts, which damage the satellite's solar cells, integrated circuits, electronic components, and sensors, and/or the need to constantly power the propulsion system.

Liquid fuels can provide high propulsive force; however, they lead to large safety management costs for fuel handling, and system redundancy. The smaller the size of liquid fuel propulsion systems, the larger the proportion of safety management and risk reduction costs become. Therefore, using liquid fuels as propulsion systems for small satellites is not suitable for private companies which need to keep the costs of production as low as possible.

Low Propulsion

High Propulsion

Comparison of Thrust Levels

・Ions Propulsion : 0.001 N

・Water Vapor Propulsion : 0.002 N

・Gas Propulsion : 1.000 N

・Liquid Fuel Propulsion: 100.000 N

Ions

Water Vapor

Gas

Liquid Fuel

Hybrid Propulsion

Dangerous

HYBRID PROPULSION SYSTEM

In 2017, the Hokkaido University Laboratory of Space Systems was selected to become a JAXA Institute of Space and Astronautical Science (ISAS) Joint University Collaboration Center, or "University Space Hub," with the aim to accelerate research and development of hybrid propulsion to enable rideshare-based deep space exploration missions.
Hybrid propulsion is the subcategory of chemical propulsion that utilizes the combustion of a solid (state) fuel, and liquid (or gaseous state) oxidizer for creating a propulsive force. Since solid fuels are inherently non-toxic, non-flammable, and non-explosive, hybrid propulsion is the safest type of chemical propulsion.

Letara is working on research and development of this hybrid propulsion technology for small spacecraft to provide safe and fast “last-mile delivery” in space, and to be the driving force of a logistics network covering the entire solar system.

High Thrust

100N

Safe

2-0-0

Affordable

A high thrust on the order of 100 N is produced for the rapid orbital transfer of small satellites - note that this is no less than the thrust of liquid fuel systems.

*100 N = 10kg on the ground
*40,000 N (and various thrust levels in between) have been demonstrated in experiments of Hokkaido University.

Since it is made from common plastic, the fuel can be handled with bare hands.

*NFPA 704 Fire Diamond standard (4 is the most dangerous, 0 is completely safe), established by the National Fire Protection Association to indicate chemical hazards

Letara's systems have a Toxicity of 2 - Flammability of 0 - and Explosiveness of 0 So there is are no special requirements for storing or handling our systems.

Recycled plastics can be used, and also any other types of solid hydrocarbons can be used as a fuel. The raw material costs are low, the size and shape can be customized with COTS 3D printers, manufacturing costs are low, the system is highly scalable, long-term storage is simply, and we can help put plastic waste on the ground to good use!