<p>Volcanic ash presents a challenge for the aviation industry. Volcanic ash is semi-transparent, absorbing in the 8-12 micron window. 3D information is needed to be able to back-calculate dose &#8211; this is a key parameter in managing airspace. To recreate the ash cloud, multiangle observations are required &#8211; making a nadir-pointing satellite ideal to perform observations for this purpose. Other mission objectives using the same instruments can also be realised, for example, as volcanic ash clouds are the primary target, there is the possibility to map new magma extrusions, lava and pyroclastic flow movements. Thermal infrared data has also previously been used to observe volcanic cycles and better understand their behaviour. There is also the possibility of including forest fires as targets of opportunity. The images required for 3D construction of ash clouds can also be used to create digital elevation models of terrain around volcanos which have application in disaster management and planning.</p><p>A CubeSat mission - Pointable Radiometer for Observing Volcanic Emissions (PROVE) - is proposed to monitor the ash cloud using both thermal infrared and visual cameras. All requirements and components were determined by students through trade-off studies. Each work package was undertaken by undergraduate and postgraduate students (both as part of research projects and on a voluntary extracurricular basis) supervised by academics. The resulting 1U+ payload consists of a thermal infrared camera (FLIR Tau 2 with a 50mm lens), and 2 visual cameras (a narrow field of view Basler ace ac5472-5gc with a Kowa LM75HC lens, and a 5MP Arducam with a 40 degree lens as a wide field of view instrument). Alongside this, a payload computer to communicate with the cameras and store data was selected (the Beaglebone Black Industrial) with a custom PCB providing connections to the instruments and bus. The software to operate the payload takes the form of a custom scheduler for an imaging pass, sending commands to the camera systems (and to the bus) to take the required multiangle images for ash cloud reconstruction.</p><p>The payload is currently in the final design and testing stage, with vibration and vacuum testing, as well as FlatSat testing before the final manufacture and integration of the payload. There is the possibility of a UK launch later this year.</p>
<p>Despite no direct observations of lightning on Mars, it is expected to occur. The planet is known to have large dust storms - which are believed to generate electric and magnetic fields. Magnetic fields are also expected in dust storms on Earth, though measurements are extremely limited. Understanding of electric and magnetic fields of this prevalent feature of the Martian landscape is vital to understanding and developing missions of Mars.</p> <p>Two hypotheses were postulated. Firstly, the vertical separation of charge is responsible for the electric field, and, secondly, that the spiralling motion of the charged particles is responsible for the magnetic field. An experimental apparatus was designed to isolate the vertical and horizontal components of the motion in a dust storm in the lab with Martian analogue material by dropping or rotating the particulates respectively. In this rig electric fields are measured using a field mill (CS110) and magnetic fields with a search coil magnetometer (LEMI 133, the engineering model from the postponed ExoMars22 mission). The rig is carefully screened from background electrical and magnetic fields.</p> <p>The equipment is currently being commissioned, and in the vertical separation mode, particulates such as polystyrene and glass beads were dropped onto a Faraday cup. By determination of the capacitance of the tank, the voltage signal can be converted into charge. In addition to this, the signals from the Faraday cup and field mill can be visualised across the time profile of a given drop. In the horizontal motion mode, the particulate is mixed with a paddle, akin to an ice-cream machine, to entrain the dust in a vortex. Results from these lab-based experiments are presented here.</p>
<p>Mars is the only planet in our solar system with an atmosphere for which there have been no observations of lightning. Despite this, it is expected to occur, with the planet known to have dust devils, which due to triboelectrification become charged. Terrestrially, dust storms generate electric fields of around 100 kV/m and there have been recordings of magnetic fields in the region of 0.4 nT. On Earth, the electric fields are not sufficient to cause breakdown. If dust devils generate similar fields on Mars, the field strength will exceed the breakdown field strength of approximately 20 kV/m, thus discharges can be expected &#8211; although these may not take the form of terrestrial discharges. The Kazachok surface platform of ExoMars 2022 will deliver the MAIGRET instrument (consisting of a search coil magnetometer, electric field antenna, and a flux gate magnetometer), which will put the capability to measure electric and magnetic fields onto Mars. To better understand the dust devils on Mars, and to aid with the interpretation of returned data from ExoMars, a series of experiments are planned to investigate the magnetic fields from charged dust.</p><p>In 2003 Krauss et al performed experiments to determine the necessary conditions for sufficient tribocharging to cause breakdown in a Mars-like atmosphere by first mixing dust to simulate wind speed, and then by dropping dust vertically at a range of pressures. Based upon Krauss&#8217;s work, two experiments will be performed with an electric field mill (CS110) and the engineering model of the MAIGRET search coil and thus two hypotheses will be tested. These are, firstly, that the vertical separation of charge is responsible for the electric field, and, secondly, that the spiralling motion of the charged particles is responsible for the magnetic field. The planned vertical drop and horizontal mixing experiments isolate these components of motion, allowing the predictions to be tested.</p>
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