How frivolously powered robots fly within the wafer-thin Martian environment

What goes up has to come down, but as any aerodynamics engineer will tell you, it’s the hard part getting it up.

On Earth, where our atmosphere is quite dense compared to many planets, we can send objects up into the air that are massive enough to be anchored to the ground by gravity using technology based on simple physical-scientific principles. As MIT puts it:

Heavier than air flight is made possible by a careful balance of four physical forces: lift, pull, weight, and thrust. For flight, an aircraft’s lift must balance its weight and its thrust must exceed its aerodynamic drag. An airplane uses its wings to lift and its engines to thrust. Air resistance is reduced by the sleek shape of an aircraft, and its weight is controlled by the materials it is made of.

But the atmosphere on Mars is about 100 times thinner than Earth’s. If you were to try and send a traditional earthbound jet to the red planet, it would likely just fade along the planet’s surface until it hit something close to the ground. There isn’t enough air support on Mars for most fixed-wing aircraft to take off, let alone stay there. And because lift flight, also known as “lighter-than-air” flight, is probably out of the question, we’re left with clever helicopter designs like NASA’s Ingenuity, pictured in the following video:

But what if we took a different route? Instead of sending an aerodynamic object into flight, we could simply build robots that float on light instead – metallic Martian angels held up on sun-kissed, wafer-thin wings.

A team of researchers from the University of Pennsylvania recently developed a light-powered levitation technique that allows tiny “airplanes” to drive themselves on light. The project was designed with the aim of solving the problem of airplane flight in the earth’s mesosphere.

According to the team’s paper:

The flight mechanism currently in use cannot be used to achieve sustained flight in the Earth’s mesosphere – the upper layer of the atmosphere at altitudes between ~ 50 and ~ 80 km. Modern airplanes cannot fly for longer periods of more than 30 to 50 km because the air density at these altitudes is too low to generate lift for airplanes and balloons.

The solution? The researchers built ultra-thin flying disks from OS film, a type of mylar that is often used in model airplanes. Per team:

We made centimeter samples with submicron thickness and different surfaces on the top and bottom. By coating the thinnest commercially available Mylar film with carbon nanotubes (CNTs) on only one side, we increased the thermal accommodation coefficient at the bottom and created a photophoretic force that floated flat disks with centimeter diameters. In particular, these floating samples can be made from inexpensive materials using simple manufacturing processes and can achieve stable airborne floating at pressures equivalent to altitudes of ~ 80 km in the atmosphere.

The next steps for research should include the construction of tiny airplanes and their testing in the Earth’s mesosphere. Interestingly, however, the Earth’s mesosphere is not that far removed from the Martian atmosphere. And that means that the work of the Penn team could be the first steps in solving traditional flight on Mars.

Of course, there is a big difference between a Boeing 747 and an object in the centimeter range. The plane proposed by the Penn team could carry around 10 mg, which is certainly not enough to move people or equipment. However, it might be sufficient to attach a chip, sensor, and transmitter to it.

In theory, we should be able to fold nanobots and sensors into OS films and make them fly around Mars with the sun’s rays for lift.

When you think of poor Percy, the Perserverence rover currently rolling around Mars and looking at rocks, you can easily imagine how millions of tiny robots swarming around the red planet could increase our planetary coverage through commands.

You can find the full paper here.

Published on March 9, 2021 – 18:50 UTC

Comments are closed.