Engineering news
Pulsing and stretching out in rippling peaks, it creates rapidly changing 3D shapes as a magnet moves around it.
Invented more than 50 years ago, ferrofluids are some of the most fascinating materials on Earth. Now, a team of scientists believe the substances, liquids containing tiny magnetic particles, could be a cheap and efficient propulsion method for satellites in orbit.
Many of the 1,300 active satellites use plasma thrusters to manoeuvre. However, technological advances are driving a new generation of microsatellites and tiny 1kg “cubesats”, which do the same job as older satellites in a more efficient way. Plasma thrusters are not suitable for the smaller satellites as they become too hot when scaled down.
Mechanical engineer Brandon Jackson has created a new computer model of an “electrospray thruster” using ionic liquid ferrofluid, a system of microscopic, hollow needles which sprays thin jets of fluid to push spacecraft. Jackson and other researchers at Michigan Technological University hope the new technology could be a viable alternative to plasma thrusters for small satellites.
Thrusters made from the ferrofluid assemble themselves and are “essentially indestructible,” said researchers at the university. “If we are successful, our thruster will enable small inexpensive satellites with their own propulsion to be mass produced,” said professor L. Brad King. “That could improve remote sensing for better climate modelling, or provide better internet connectivity, which three billion people in the world still do not have.”
The Michigan Tech team recently received a second research contract from the U.S. Air Force Office of Scientific Research. It hopes the thrusters could practically be used in several years.
"Space junk"
One of the most pressing issues in satellite technology is the vast amount of “space junk” left in orbit: approximately 7,000 tonnes of high velocity debris posing a huge risk to satellites and spacecraft. More accessible propulsion systems could help reduce this problem, said Hugh Lewis from the University of Southampton.
“For me, the greatest benefit coming from the addition of a propulsion system to a cubesat, beyond the science benefits, is the ability to dispose of the satellite once it has completed its mission,” he said. “Post-mission disposal is one of the most effective measures available for preventing the build-up of space debris.”
Satellites using the propulsion system could be directed back towards Earth where they would burn up in orbit, said Dr Lewis.
However, he said a rapid increase in the number of manoeuvrable satellites could bring its own problems. “Cubesat operators have little or no experience in dealing with conjunctions or disposal, or the responsibility for preventing a collision,” he said. “Adding a propulsion system also adds this responsibility and a vital need for experience; something that might be difficult for some operators such as universities and small enterprises to deal with.”
The change would be similar to suddenly having lots of learner drivers on the roads, he said.
The article on the ferrofluid electrospray thrusters was published in Physics of Fluids.