It is astonishing to see how far the magnetic survey technology has progressed. Ever since they were paired with drones, they have transformed geophysical research. An airborne magnetometer has completely changed the scenario of geophysical exploration. The smallest changes in magnetic field are captured by the magnetometer and researchers can’t get enough of it.
What started as a simple expedition by the curious minds at SPH Engineering has become an industry-standard in less than 10 years! The UAV drone services giant wanted to find a WW-II-era plane buried in the icy depths of Greenland. They used a drone to fly over the large snowy island and included a magnetometer on its tail to find out any residual magnetic signals.
This groundbreaking effort remoulded the way airborne geophysical explorations have been done since then. But the airborne magnetometer used in the search and identification operation does make one reflect. For instance, what prompted the research behind drone applications for ground exploration?
Let’s try to find the answers to these questions in this article.
How were magnetic surveys carried out before?
There was nothing ‘airborne’ about magnetic surveys before. Everything was ground-based. In the late 18th century, it was identified that some rocks have magnetic properties. These rocks were found to have an impact on the Earth’s magnetic field. Magnetic compasses were used in mining operations back then to take the measurements of magnetic declination.
The first example of an airborne magnetic survey was found way back in 1785. It was an experimental survey done using a manned hot-air balloon. It continued in the 19th century but things didn’t move too far. Many iron-ore deposits were mapped and identified as a result. But ground-based magnetic surveys were still the dominant mode of geophysical exploration in the 19th and early 20th century.
Why was the need felt for the development of a magnetometer?
It took two world wars to speed up the development of complex magnetometers. During the First World War, it was found that magnets could be used to detect underwater submarines.
The German air pioneer Ferdinand von Zeppelin or Graf Zeppelin as he was known, invented the saturated core ‘fluxgate’ magnetometer in 1928. This development was so significant that the results were not published until 1936. Similarly, the erstwhile USSR was also carrying out airborne magnetic surveys in the late 1930s. They did this using the induction coil technology.
You may ask, why were the airborne magnetic surveys a matter of such intense competition in the 20th century? Why were the Nazis and the Allies in a race to develop an advanced airborne magnetometer?
The answer is two-fold:
- finding iron-ore deposits, and
- detecting the advanced, virtually undetectable U-boat submarines.
Iron ore because the Western world was busy in an armaments race and they needed tanks and ammunition at their disposal.
U-boat detection because the US and Britain wanted quality airborne magnetometers. The latter were inflicting heavy casualties on the allied forces and Roosevelt and Churchill were desperate for a solution.
Against this backdrop came the development of the new fluxgate magnetometer in 1940. It was a significant improvement over the earlier rudimentary versions. However, even this magnetometer had one major flaw. It couldn’t measure continuous changes in the earth’s magnetic field while being mounted on the aircraft. It was also ineffective over certain latitudes and just couldn’t deliver the desired results.
How are magnetic surveys done now?
The world entered a new phase of cold war between the Capitalist and the Communist blocs after the Second World War. It ushered a renewed technological competition between the major powers. New advancements were being made in the field of magnetic airborne detection and unmanned aerial vehicles. The internet and the ensuing IT revolution gave a major fillip to these developments. We are now in a position where drones are being tied with magnetometers to carry out magnetic explorations.
These drones are often studded with advanced thermal cameras and magnetic sensors to detect the smallest changes in the earth’s magnetic field. They are operated using an autonomous drone-flying software like that of UgCS. The latter, developed by SPH Engineering, is a huge milestone in precision drone-flying operations. The latitude and longitude can be pre-programmed into the drone software along with other complex geophysical datasets. The flight planning software runs on a PC/Mac and even works offline.
Once the data is input into the software, the drone flies on its set course with perfect accuracy and delivers results quickly. The airborne magnetometer employed on the drone captures the magnetic signals and relays them back to the user.
Key Takeaway
From finding hidden mineral deposits and tracing the location of lost World War-era planes, the airborne magnetometer is indispensable. It has brought quick efficiency to the world of geophysical exploration unlike ever before. When integrated with a drone powered by accurate flight planning software, the magnetometer delivers precise results.
