Tracking Changes in the Earth’s Magnetic Field Using a Smart Phone

Phones in Space

Since the existence of humanity, people have looked up to the stars with wonder every night thinking it impossible to one day reach that tiny speckle in the dark sky. But when man first stepped onto our moon, we realised just how much was possible and countless discoveries have been made since. Now, with 21st century technology, we are planning to take space exploration to higher level. Using everyday technology, we plan to show how anyone can help make discoveries and breakthroughs, even young children. To understand our project, you will have to understand magnetism and phones first.

Magnetism

Magnetism is a force used by many regularly. It’s useful in sticking pictures to your fridge but also plays many important roles. Most of the technology we use every day has some sort of magnetic part which it can’t function without. Earth is a magnet itself, so are some other planets. Magnets work two ways. They can either attract or repel. Magnets always react to other magnets but there are some materials that are not necessarily a magnet that still react. A good example is iron, it will not stick to your fridge but still reacts to magnets. Magnets also help make discoveries. Magnets are used in many sensors, enhancing their abilities. They are also used in space to help detect any magnetic stones or other samples taken from outer space. But did you know the world’s biggest magnet is the Earth itself.

So how is the Earth a magnet?

The Earth looks way too big to be a magnet and you wouldn’t think soil and ocean would be magnetic. However, since 1600, we have known the Earth had magnetic properties. Now we know why. The molten iron and nickel that surrounds the Earth’s core is the source of most of this magnetism (See figure 1).

Figure 1: Source: http://www.2facts.com/stories/graphics/sg05005a.gif

The intensity of the magnetic field created by the Earth can be mapped. This changes all the time but Figure 2 shows an example of what it might look like.

Source: https://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml

Figure 2: Map of Global Magnetic Intensity

There are numerous important skills we can learn from mapping the magnetic field. Firstly we can learn about mapping conventions and how to read maps. We would also learn about the countries around the world and a map such as that presented in Figure 1 would encourage many questions. For example, why does the South Atlantic Anomaly exist? Why is the magnetic field so strong in many parts of the ocean and how do waves affect the magnetic field? By actively taking measurements with land-based phones and then using SAM – our space phone (it stands for Space Accelerator and Magnetometer), we can all feel like real scientists. Plus we can learn to map things and graph features in X, Y and Z dimensions because our magnetometers will provide us with that data.

We can also look at the magnetic field in a smaller scale, for example Australia, or just South Australia and look at how that changes. We might for example get higher readings at places with iron rich environments, such as the Pilbara area in Western Australia or South Australia’s Roxby Downs.

The Effect of the Sun

The Earth is a dynamic system and one of the major influences on it’s magnetic field, is the sun. The solar wind radiates out from the sun towards the earth and consists mostly of protons and electrons with an embedded magnetic field (from the sun). This is shown in Figure 3.

Source: https://qph.ec.quoracdn.net/main-qimg-be67602430f11d5561bc0edfb37260b7

Figure 3: Interaction of solar winds with Earth’s Magnetic Field

Figure 3 shows that not only does the earth have a magnetic field, which extends about 50,000km from Earth, but it is affected by the solar winds. The solar wind radiates out from the sun towards the earth and consists mostly of protons and electrons with an embedded magnetic field (from the sun).Near the earth, within the magnetosphere, the earth's own magnetic field dominates and the solar wind is deflected (although the geomagnetic field is compressed on the sunward side and drawn out into a tail on the other side). However, some solar wind does enter the magnetosphere and the charged particles follow the magnetic field - the solar wind is not "sucked in", even though it looks like it in the diagram. The particles are simply directed to the poles by the Earth's magnetic field. These particles interacting with the atmosphere is what causes the aurora – the beautiful light displays seen at the northern and southern poles.There are large populations of these particles around the earth which are "trapped" in the earth's magnetic field, forming the radiation belts. This is a harsh radiation environment which must be taken into account when designing spacecraft.

Phones

Phones are much more recent than space but, to much of the population, just as important. Phones have been around for many years, starting with the wired telephone. Though now in the 21st century, smart phones are much more popular. Used by almost 90% of the population every day, they have got to be the most popular object you could find. Phones are very important to everyone. Over the years, the most vast, international program has developed, often called the internet. Phones have allowed us to communicate with friends, family and colleagues on a daily basis without any difficulties. Along with phone and

messenger, you can download some very useful apps. To most, useful means games and online shopping apps but you download some handy science apps as well. These include apps that measure temperature, humidity, magnetism, etc. These apps will play a vital role in our project.

There are two essential items in a phone that will help us in space: an accelerometer and a magnetometer. The accelerometer senses the phones movement on an x, y and z axis. This is what allows us to play many games and track how many steps we walk during the day. The magnetometer measures the magnetic field in micro tesla units.

Other important features are the battery. We are recommending the Galaxy S7 at this point because many people have suggest and android phone will be easier to work with. The lithium-ion batteries can hold a change for more than a day and can be recharged wirelessly. The motherboard is also very thin and the weight is appropriate for the payload. We have also collected information about an ultra-compact high performance eCompass (LSM303DLHC) module that might be something adult scientists can help us with if we get through this round.

The magnetometer should show a field of between 25 and 70 microT (depending on the orientation of the phone) while on Earth. An iPhone magnetometer has the following characteristics: Sensitivity, Accuracy, Range.

Our Aim

We want to make kids realise how awesome the Earth is.

We want kids to know the magnetosphere is a huge collection of currents. That the sun affects this system

o Solar storm events can make big changes in the magnetosphere leading to aurora, but also satellite outages and power blackouts.

That magnetic fields are important in everyday life That we can work together to make STEM learning totally fun!

Methods

We plan to take a citizen science approach to this project and get as many school children involved as possible. One of our key contributions will be providing the methods for other schools to use their phones as magnetometers. We’ll tell them which app to download, when to time their runs, how long to conduct them for and we’ll ensure all the data is time-stamped so adult scientists can collate it. We’ll also provide activity sheets for them to explore magnetism in general. For example, what happens when they put their magnetometer near the fridge? How does the reading differ if you do it on a sunny day compared to a rainy day, or the night compared to morning? Using our YouTube channel, we’ll point the classes to other resources, such as those on the Geoscience Australia, NASA

and SOHO where we can look at the sunspot index and see if higher values correspond with a higher magnetic field reading.

Using a mobile phone magnetometer and other sensors, we will package the sensor data with timestamp and transmit to ground. The timestamp should accurately provide position data for comparison with a set of ground based magnetometer measurements.

The iPhone will be programmed to start measuring the magnetic field at eleven minute intervals. The choice of a prime number is a check and balance so the recordings will be at different times every day. The ISS orbits Earth about every 90 minutes so we would have lots of data by the end of the experiment. Data will be time stamped.

We believe we will have access to a USB charger once the payload reaches the ISS but we understand we will need additional help to make our experiment feasible.

We know that the Surface Magnetic Field Strength varies from approximately 20 to 60 Tesla and varies over a period of 6 months on the order of +0.1 T

It is expected the range of magnetic fields experienced at a distance r from the Earth’s centre to be approximately:

|B|(r )≈Bo( ℜr )

3

Where ℜ is Earth Radius (6371 km) and the ISS orbits at approximately 330-435km

Thus the reduction from surface is expected to be approximately 84% (Source: https://physics.stackexchange.com/questions/267158/how-strong-is-earths-magnetic-field-in-space ).

Southcott Engineering has helped developed a casing for us that will protect the phone.

Maximum volume:

1 litre is 1000cm^3 10cm x 10cm x 10cm max space for experiment or equivalent to fit the 1000cm^3 size

Our container will be manufactured using Perspex.

Dimensions of the container are Length: 214.742613mm

Height: 80.242613mm

Width: 141.942613mm

Our Communication Strategy.

We plan to use our logo (SA faunal emblem: southern hairy nosed wombat, infront of a sunspot) and great acronym (Mission MARSUPIALS) to brand our materials. We have created our own YouTube Channel and will enjoy broadcasting updates several times every term. There is already so much great space information available, from data to crafts – we’ll test it, comment on it and run competitions around the state.

ChallengesMagnetometers usually are calibrated before use, by rotating them in a circle (or all three axes). We are not yet sure how to do this after it’s in place on the station. If this is not done, there will be biases from the magnetic field of the station, in close proximity.

Reliably starting the phone in the “measure and send mode” after powering it up is still to be worked out. How do we save and send the data to Earth? How do we remotely activate the phone? We’ll need to prime it to start with and we are hoping to get IT staff to code an app that looks at the data every 9 mins. We know there are Hackathons run by Defence SA in November and there will be 3-4 before launch. We’ll use forums such as this to help us develop and test the best app possible. While our initial thought is to use a whole phone, it might be that we use key components of the phone.

Bruce Wedding has told us we can use his vacuum facility in the physics lab to test our experiment once we are further along. We know that the temperature variation will influence the electronics and strength of the readings (strength will be greater when the sun is hitting it). We were worried that the magnetic items on the ISS would affect our readings. However, most metals used in space are non-ferrous (which means that they won’t have a magnetic field of their own or affect the measurements). Ady explained to us that it is possible to shield magnetic field, but it would be hard to shield the phone and still make measurements. Also, the only materials that can shield the field are ferrous metals which are heavy and so avoided in space.

In order to work out where the measurement is taken, we’ll need either a feed from the ISS mission system of location, or to know the time – so we need our data to be time-stamped. The messages sent down may have a timestamp, so there would then be a minor latency bias, which possibly could be corrected knowing significant Earth measurements of field.

GPS is what is often used in phones to keep accurate time. We are currently not sure if GPS positioning will work on the phone, as at that altitude, the GNSS system chips (which decode GPS, Galileo, GLONASS satellites to get a position) may inhibit the output as a precaution against use as a weapon.

There were some problems with Galaxy compass in 2016. Further investigation needed.

Phones are vulnerable to cosmic rays or radiation breaking memory etc. It may need appropriate (non-magnetic) shielding.

What do we do if it fails?We think if the sensor or phone fail for whatever reason, other magnetic sensors data could be supplied to schools either for comparison or in place of the expected data from the phone

STEM STEM learning has occurred through a range of disciplines. Students have gained a deeper understanding of the Earth’s Magnetic Field. All curriculum areas were involved as their investigations deepened. At first basic scientific principles of magnetism were investigated by students. Their knowledge expanded when they investigated the Earth’s magnetic field and its connection to protecting the Earth from the sun’s shortwave radiation. They concluded that “If Earth had no magnetic field then it would be bombarded with solar wind radiation and would be inhospitable to life!” Collecting data and tracking changes in the Earth’s Magnetic Field over a one-year period, became important to them as they would be looking at changes in their own collected data and analysing it to create a model of the Earth’s magnetic field providing many learning opportunities within the curriculum – and make them powerful learners.

The information gained could be shared with all students in all schools so that a greater understanding of how the Earth’s magnetic field affects all life on Earth. They discovered many interesting facts along the way, such as, scientist’s belief that whales and birds use the Earth’s magnetic field to help them navigate during migrations. Solar storms can lead to short term magnetic latitude changes that confuse the animals and various whale strandings have been linked to this phenomenon.

STEM Cycle process Identifying the need - we gained a greater understanding of the Earth’s Magnetosphere.

Investigating- Through researching we understood the Scientific principles involved.

Imagining- We developed a possible solution to the collection of data to further our understanding

Planning- we consulted widely to come up with a viable plan.

We are looking forward to Creating and building a prototype in the next stage. Testing and evaluating the prototype and involving as many people as possible in our process to further understand our World.

References

GEONS User Guide. 2017. Introduction to Magnetism.

Geoscience Australia. 2017. http://www.ga.gov.au/

http://www.swpc.noaa.gov/products/real-time-solar-wind

https://physics.stackexchange.com/questions/267158/how-strong-is-earths-magnetic-field-in-space

NASA. 2017. https://www.nasa.gov/

Stepišnik, Janez (2006). "Spectroscopy: NMR down to Earth". Nature. 439 (7078): 799–801. Bibcode:2006Natur.439..799S. doi:10.1038/439799a.

Acknowledgements

This report was put together by Preet and Inika with help from adults – Delene Weber and David Dempsey. We would also like to acknowledge space scientists Ady James and Graziella Caprarelli who gave us answers to several questions, as well as geologists Tom Raimondo and Laura Rollinson and Physicist Bruce Wedding.