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This illustration shows NASA’s Dragonfly rotorcraft-lander approaching a site on Saturn’s exotic moon, Titan. Taking advantage of Titan’s dense atmosphere and low gravity, Dragonfly will explore dozens of locations across the icy world, sampling and measuring the compositions of Titan's organic surface materials to characterize the habitability of Titan’s environment and investigate the progression of prebiotic chemistry. Credits: NASA/JHU-APL
By Kade
Dragonfly is a drone to Titan to find out how life got on Earth. But before we learn about dragonfly we need to know about Titan first. Titan is one of Saturn’s moons and it is the only moon in our solar system that has a noticeable atmosphere. Titan also has an ocean of methane which evaporates into clouds which then makes it rain liquid methane.The amount of information scientists can get from Titan is a lot. The problem is that Titan is 745,645 miles away from the Earth which makes it really difficult to get the information and the clouds of methane makes it even more difficult to gather data. In 1997 NASA, the European space agency, and Italian space agency did a collaboration to make Cassini a space probe on a 7 year journey to Saturn. The probe was made to study Saturn's entire system which includes its rings and natural satellites. But Cassini didn't make the 7 year journey on its own. Attached to the space probe was a small lander called Huygens which was hoping to become the first spacecraft to land on Titan. Several months after entering Saturn's orbit, Huygens detached itself from Cassini then started its journey to Titan and started sending back important details about Titan’s environment which includes the fluid properties of the atmosphere and the nature of Titan’s surface. As it started to descend, Huygens recorded the accelerator data which could be used to deduce properties which include the density of the fluid,and the aerodynamic properties of the probe. It also took the temperature and pressure to teach us about the thermodynamic properties of the atmosphere. After two and a half hours went by, descending through the unknown, Huygens finally landed successfully on the surface of Titan. Which makes It was the furthest spacecraft landing from Earth to this day that earth has ever completed. Huygens was only built to survive for about 90 minutes after landing on the surface of Titan. Huygens successfully recorded and sent back 350 images. Revealing a world weirdly similar to ours.
Ingenuity, pictured above, is a drone helicopter that is going to mars with Perseverance, the Mars 2020 rover. This little drone will act as a technology demonstration to see if powered flight can work on another planet. It is mostly autonomous meaning it can fly without someone at the controls. It is hoped that Ingenuity can give scientists a look at places on mars that are too steep or slippery to send the wheeled rover. If successful, Ingenuity might spark many more flying drones to go to different planets.
Now let's learn about dragonfly. Dragonfly is a mobile lander with 8 large rotors that will help it fly. Building Dragonfly will be a really difficult challenge but with the data gained from Huygens will be incredibly helpful in building Dragonfly. Anything from the propellers to the battery and energy source is what will be challenging. Dragonfly will have a lot of the same scientific instruments as the curiosity rover. It will have a skid mounted drill to take the soil samples and will run it through a mass spectrometer to learn more about the soil composition. When it lands a seismometer will transmit information about quakes and reveal the thickness and nature of titans icy crust sitting above what is believed to be a liquid water ocean. Scientists think this is because Cassini witnessed the surface shifting position by 18 miles in 2 years indicating that the crust is floating on top of some kind of liquid. With Dragonfly there we can look forward to incredible photos of Titans surface like the photos from mars are being studied and evaluated. Since the air is thicker on Titan and the gravity is one seventh of Earth’s gravity, Dragonfly can achieve more thrust and sinse Dragonfly is able to achieve more thrust it will reduce the consumption of energy. But finding the energy to fly on the surface of a Titan is not that easy. Because of Titan’s distance from the sun and the thick atmosphere, the sunlight on Titan's surface it's about 100 times weaker than it is on Earth. So making solar panels useless. But with knowledge in different types of energy sources through missions like the Curiosity rover which was powered by a Radioisotope Thermoelectric Generator also known as RGT. RGT works by converting the heat from the natural decay of a radioisotope into electricity. This isn't traditional nuclear energy. RGT does use radioactive materials to generate electricity but not through nuclear fission. It uses a principle called the seebeck effect to generate electricity. The seebeck effect generates an electric current through a heat differential as charge carriers will move from hot to cold if there is a heat source and a way for cooling we can generate a sustained electric current will be generated. Radioactive substances generate heat as they decay. But it’s important to choose a suitable radioactive material and that will be a challenge. With any spacecraft a lightweight and compact design is important. It needs the material to have a long life to ensure a long lived energy source and it also needs it to produce alpha waves. Alpha waves as a form of radiation is easily converted to heat in a compact space. As a result of those requirements Plutonium-238, Strontium-90, and curium-224 are the most commonly used fuels. Next there needs to be a material which is both a thermal insulator to maximize the temperature and also an electric conductor to maximize our current. Those two material properties are normally linked. Materials like Copper are both a good thermal and electrical conductor. Materials like iron are a poor thermal and electrical conductor. Using those materials together can create a crude thermoelectric generator. But the efficiency is really low. If we could create a material with both of the best properties we can achieve a much higher efficiency.
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