Raphael Thys
The population of satellites in low Earth orbit (LEO) is expected to rapidly rise over the next decade. With the increased number of space objects comes a higher risk of collisions between active satellites, inactive satellites or other space debris. Currently, most small satellites rely only on atmospheric drag to deorbit — causing vehicles to remain in orbit well past their useful lifespan and heightening the risk of debris creation through either internal explosion or collision with another object.
The rapid increase in the number of orbiting satellites has increased the risk of space junk.
The existing population of human-made objects in LEO has already caused space junk to become self-sustaining due to additional collisions between debris. In response, a team of Aerospace scientists and engineers are devising a novel technology to reduce the amount of debris in this critical environment. The solution, known as the Lithium-ion Battery Deorbiter, will utilize the battery already onboard a spacecraft to reduce debris by igniting the battery into thermal runaway and generate thrust for deorbit.
“Everybody knows about lithium-ion batteries and their risk to go into thermal runaway and spew fire,” said Dr. Joseph Nemanick, a senior research scientist in the Energy Technology Department, “the Lithium-ion Battery Deorbiter is turning that weakness into a strength.”
By activating thermal runaway in a controlled manner, the red-hot gasses produced are channeled through a nozzle to generate deorbit thrust. This approach is the first zero-added-mass onboard spacecraft technology capable of reducing orbital debris—helping to protect low Earth orbit from additional space junk.
The Li-Ion Battery Deorbiter activates thermal runaway in a controlled manner and utilizes the red-hot gasses produced to generate thrust for deorbit.
“Most small satellites have no propulsion at all and are stuck in the orbit where they were originally delivered,” said Dr. John DeSain, a senior scientist in the Propulsion Science Department. “Normally atmospheric drag is the only way for the satellite to deorbit, but by using the satellite’s battery as a propulsion unit, the overall lifetime and chance of collision can be decreased.”
The team has already demonstrated proof of concept in the Aerospace Propulsion Research Facility. Scientists activated space rated battery cells that achieved effective thrust comparable to a commercial solid rocket motor. The projected thrust is sufficient to reduce residual orbit time for a small satellite by 55% in LEO.
Even with these favorable findings, however, barriers still exist. The biggest likely obstacle is altering the current perception of thermal battery runaway.
“Telling people that you can skillfully harness one of the scariest things that can happen in space takes a lot of convincing,” said Nemanick. “Looking at this event from a pure chemistry perspective, however, there is significant overlap between battery thermal runaway and a normal solid rocket motor.”
Further testing of this technology is being conducted by the Aerospace Propulsion Sciences Department. Of particular interest is the development of different methods for controlling the amount of thrust generated, reliable triggering, and ensuring safe activation of thermal runaway.