The idea of a spacecraft being propelled by a molten grain of salt seems like a dream. More like science fiction or fantasy, but the same stands true now with a new instrument called electrospray thruster. A team of engineers from University of Maryland can be thanked for this accomplishment. They developed a bunch of very small rockets with a hope that the same will be used in space application during coming days. These small rockets were recently placed under a Transmission Electron Microscope (TEM).
Basically Electrospray thrusters are smaller than a standard drop of ionic liquid. Application of strong electric field will lead to evaporation of molecular ions from the tip of electrospray thruster. The ion spray leads to development of small force which is much more less than weight of single strand of human hair. It might not look appealing on earth’s surface but will be highly sufficient in space vacuum to propel small objects ahead.
However, there is one small issue with ion rockets. Many a times, the thruster tip forms a strange tree-like framework disrupting the ion flow and turning the ionic liquid into gel. The team working on it tried to find the reason and answer to this problem. This was a herculean task, no doubt. A team member, Lyon B. King, says, “This was no easy task. Getting a close look at these droplets is like looking through a straw to find a penny somewhere on the floor of the room. And if that penny moves out of view, like the tip of the molten salt needles do - then you have to start searching for it all over again.”
They were finally able of catch up with the progression through a TEM that allowed them to see all images at very high resolution. With the help of these images, they could identify the high-energy electrons that were causing damage to ionic liquid molecular structure. This turns the liquid into gel and interfered with ion flow disruption. The team’s leader Kurt Terhune says, “We were able to watch the dendritic structures accumulate in real time, The specific mechanism still needs to be investigated, but this could have importance for spacecraft in high-radiation environments." Much needs to be done in this respect,but well begun is half done. If a large number of such thrusters are combined, these will be able to propel a large sized spacecrafts.