Neodymium magnets are being sent into space to help collect dust from the surface of Mars. From what we know Mars is a dusty place, with some dust proving extremely magnetic. The magnetic materials carried in dust grains may be freeze-dried remnants of the planet´s watery past. Therefore, an examination of these particles and their patterns of build-up on magnets of varying strength can reveal clues about the planet’s geologic history.
Where do magnets come in?
Each rover will carry several magnets, which will all analyse the dust particles found on Mars. Previous Mars landers had magnetic arrays that collected magnetic particles from the surface and from windblown dust near the surface. However, the Mars Exploration Rover version of the experiment contains magnets in which attracts airborne Martian magnetic materials which are higher in the atmosphere. The rovers robotic arm moves the collected magnetic materials to a position where they can be investigated.
Magnets array: The three elements
The experiment is a significant scientific step beyond its predecessors because of the unique mineralogical capabilities of the Mössbauer spectrometer. The magnets array includes three elements:
- Filter and capture magnet
- Sweep magnet mounted on the rover deck
- Four Rock Abrasion Tool (RAT) magnets
Both the filter and capture magnets are mounted on a magnet array on each rover, which is accessible to the Mössbauer spectrometer and APXS. The slightly stronger ‘capture’ magnet is designed to attract all iron-containing dust and magnetic-iron dust. Whereas, the weaker ‘filter’ magnet is designed to attract only the most magnetic dust. Both types of magnets are each contained within an aluminium disk. In a position clear of the solar panels, each magnet will be positioned as high as possible on the rover.
Capture and filter magnets
The capture magnet is specifically designed to collect a similar layer of dust as efficiently as possible, and to provide a relatively constant magnetic field at the position of the dust layer. Based on research, it’s expected that it will take 15 Martian days for the rover to collect enough material for analysis.
In a similar way, the filter magnet will also gather flying dust particles dropping to the magnet from the atmosphere. This magnet is intended to collect a standardized layer of strongly magnetic dust, and to avoid weak magnetic dust. It’s estimated that it will take up to 30 Martian days for the magnets to gather enough particles for examination.
Sweep and RAT magnets
The sweep magnet is designed to determine whether magnets are rejecting a population of more strongly magnetic particles from the airborne dust, or whether all dust particles have similar magnetic properties. To do this, the magnet consists of a thin-walled magnetic tube magnetised along its symmetry axis. This design makes it possible for a strong magnet to deflect the paths of wind-transported, magnetic particles arriving at the surface of the magnet. Magnetic particles will gather on a fine ring interrelated to the magnetic tube. Inside the ring magnet, the core surface will only collect non-magnetic particles. However, at a greater radial distance from the ring magnet, both magnetic and non-magnetic particles will gather. Pancam images of the sweep magnet will provide data on the dust collected, and therefore provide information on the relative amounts of magnetic versus non-magnetic particles that are present in the Martian dust.
The Rock Abrasion Tool (RAT) grinds away rock surfaces, when this happens the rock particles sample and concrete the magnetic portion of the particles for examination by the panoramic camera. The images from the camera can then be used to characterize the different types of magnetic minerals in the Martian rocks. RAT magnets have various strengths therefore providing a range of conditions which enable magnetic particles to be attracted and held. After examination, the particles will be cleared from the platform through a temperature-driven retraction mechanism. Since temperatures drop at night, the collection area slides down into a sleeve, thus pushing off any remaining particles on the surface and clearing the way for new rock samples.
Magnetism with Goudsmit UK
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