Nanofabrication Enables Mesosphere Atmospheric Sensors

The earth’s atmosphere is large, extending around 10,000 kilometers from the surface of the planet. It is so large, in fact, that scientists divide it into five distinct sections. There is a particular section which has not received much attention due to the difficulty of maintaining a profession there.

The plans and balloons can visit the troposphere and the stratosphere, the two sections closest to the ground, while the satellites can sit in orbit in the thermosphere and the exosphere, allowing a platform of coherent observations. But the mesosphere, the section in the middle, is too close to having a stable orbit but too sparse in the air density for planes or traditional balloons to operate.

Consequently, we do not have much data on this subject, but it has an impact on climatic and meteorological forecasts, so scientists simply had to do a lot of assumptions about what that is. Now, a new study by researchers from Harvard and the University of Chicago may have found a way to put stable detection platforms in the mesosphere, using a new flight mechanism known as photophoresis.

The mesosphere itself is located between 50 and 85 km, and although it is not technically considered to be “space”, it is very different from the lower levels of the atmosphere to which we are more used. He is assigned both by weather conditions below and above, reacting to solar storms as often as hurricanes. Since it serves as an interface level, it plays an essential role in the way the layers above and below also react.

But we have not been able to place any stable surveillance equipment due to the difficulty of the two types of continuous surveillance systems we have – balloons and satellites. This led to the nickname “Ignorosphere”, because scientists were forced to ignore essentially the existence of this atmosphere because of the lack of data.

Photophoresis feeds a new atmospheric sensor

Enter the new newspaper, published on August 13 in Nature,, On long -term sensors in the mesosphere. Photophoresis is a process where more energy is created when the gas molecules bounce on the “hot” side of an object than its “cool” side. In this case, the hot side is the side of the object facing the sun, while the fresh side is the bottom facing the earth. The effect is only perceptible in low -pressure environments, which is exactly what the Mesosphere is.

Admittedly, the strength of photophoresis is tiny, the researchers had to develop really tiny games to have a chance to take advantage of it. They recruited experts in nanofabrication techniques to manufacture structures on the level of centimeters as proof of concept and tested them in an empty chamber designed to have the same pressure as the mesosphere.

The prototypes reacted as expected and managed to levitate a structure with only 55% of sunlight at a pressure comparable to that of the mesosphere. This marks a first that anyone who has ever demonstrated a functional prototype of a flight powered by photophoresis, mainly due to the light of the structure itself.

The devices fueled by this technique can be sent to monitor the mesosphere, but they could also be useful further. Mars is an obvious candidate, because his atmosphere at low pressure and sparse is both characteristics of the planet but also largely unexplored at different layers. Other planets and moons could also be potential targets – anything that has a sufficiently exhausted atmosphere to support a levitation spacecraft could be served by one of these leaflets.

Unfortunately, there is still an advanced engineering to do. The nanofabrication technique used to build the flight structure did not include any functional equipment, such as wireless communication sensors or equipment. A structure that floats simply without transmitting data is not scientifically useful, so for these devices to start making the type of scientific impact they hope, nanofabrication techniques must be improved to create a functional payload.

Researchers, however, have no doubts that this is possible, and has already created a start-up called Rarefied Technologies, which was accepted in the Breakthrough Energy Fellows program last year. With this support and certain research in progress in nanofabrication, I hope that it will only be a matter of time before seeing sensors of centimeter size dispersed in any “the ignorosphere” and beyond.