NIST scientists have developed a new fuel gauge to help satellite operators pin down the actual quantity of fuel left in satellites.
Originally devised by NASA technology transfer manager Manohar Deshpande, the new prototype can digitally recreate a fluid’s 3D shape based on its electrical properties. offering reliable fuel measurements which could help prevent satellites from colliding and keep them operational for longer.
Liquids aren’t as well behaved in space as they are on Earth, notes the NIST’s team leader, mechanical engineer Nick Dagalakis.
Inside a spacecraft, microgravity allows liquids to freely slosh and float about. This makes it extremely difficult to pin point the actual amount of fuel still left in a satellite.
Letting a satellite’s tank run dry could leave it stranded in its original orbit with no fuel to avoid smashing into other satellites and producing dangerous debris clouds.
To reduce the probability of collision, operators save the last few drops of fuel to eject satellites into a graveyard orbit.
This however leads to unnecessary fuel wastage, contends the NIST team: By the time a tank is low, the estimates become more like rough guesses and can miss the mark by as much as 10%.
The NIST fuel gauge could thus be a game changer in space. It uses a low-cost 3D imaging technique known as electrical capacitance volume tomography (ECVT) to measure the object’s ability to store electric charge – courtesy of electric field-emitting electrodes.
The sensor electrodes for this study were produced by printing patterns of ink over copper sheets with a flexible plastic backing.
A corrosive chemical was then used to carve out the exposed copper, leaving behind the desired strips of metal.
Dagalakis and his team tested the sensors by lining the interior of an egg-shaped container modeled after one of NASA’s fuel tanks.
Throughout the inside of the tank, electric fields emitted by each sensor can be received by the others.
But how much of these fields end up being transmitted depends on the capacitance of whatever material is inside the tank – whether it be liquid hydrogen or hydrazine:
“If you have no fuel, you have the highest transmission, and if you have fuel, you’re going to have a lower reading, because the fuel absorbs the electromagnetic wave,” notes Dagalakis.
“We measure the difference in transmission for every possible sensor pair, and by combining all these measurements, you can know where there is and isn’t fuel and create a 3D image.”
Image and content: NIST