Space Science Research
Suzie is a Professor of Space Physics at the University of Leicester. She specialises in combining satellite and ground-based data to understand the interaction of the Sun with the planets in our solar system, an area of research known as Space Weather
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BepiColombo!
The BepiColombo Spacecraft launched successfully from the European Spaceport in Korou, French Guiana on 20th October 2018, starting a seven-year journey to the planet Mercury. On board, the Mercury Imaging X-ray Spectrometer (MIXS) instrument, built at the University of Leicester, designed to answer the mysteries of the composition and evolution of the planetary surface!
1. Space Weather
Space weather is the study of the interaction of the solar wind with the Earth's environment. The Sun emits ~one tonne per second of protons and electrons out into the solar system, travelling at ~400 km/s, and this plasma takes ~2-3 days to reach the Earth. The plasma drags the Sun's dipolar magnetic field out with it, and this forms the interplanetary magnetic field. As solar activity varies over an (approximate) eleven year cycle, so the solar wind properties also change, and we forecast the most extreme conditions, producing a space weather forecast.
Earth's magnetic field carves out a cavity in the solar wind called the magnetosphere, protecting us from harmful radiation and energetic particles from the Sun. For the most part the solar wind sees the magnetosphere as an obstacle that it flows around, but under certain conditions the interplanetary magnetic field and the Earth's magnetic field interact, such that energy and momentum from the solar wind are stored in the Earth's magnetic field.
Eventually this stored energy must be released, and the energy release is explosive, accelerating particles down field lines into the Earth's atmosphere. These particles cause the atmosphere to glow, generating the aurora borealis and aurora australis, or northern and southern lights. These form a ring centred on the magnetic north and south pole - great places to view them from are northern Norway, and Canada.
2. Mercury's Magnetosphere
Mercury has a weak magnetic field and is located in the inner solar system (~0.3-0.45 AU) and therefore experiences extreme space weather. It is believed that the solar wind may be sufficiently powerful to squash the Mercury's magnetic field beneath the surface of the planet, allowing the solar wind to directly impact the surface. Mercury is a strange planet though, it has a dipole magnetic field that is not centred at the centre of the planet (offset to the north by 1/5 of a Mercury radius) and the axis of the dipole is closely aligned with the rotation axis, a rare situation in our solar system. Mercury also rotates very slowly (it takes 59 Earth-days to complete one Mercury-day), and therefore the side facing the Sun is extremely hot (~450 degrees) while the side facing away from the Sun is more like minus 180 degrees. This makes it an extremely inhospitable place for a spacecraft!
NASA sent the MESSENGER spacecraft to Mercury, launching in 2004 and arriving in 2011 (yes, it takes 7 years to get into orbit around the planet Mercury). MESSENGER was in orbit for 4 Earth-years, and I have authored numerous papers studying Mercury's magnetic field structure and dynamics using a combination of magnetic field and particle data taken by MESSENGER.
To find out more about MESSENGER and the top ten discoveries of the mission, click here for the Johns Hopkins website!
3. The BepiColombo Mission
I am a co-investigator on the Mercury Imaging X-ray Spectrometer (MIXS), an instrument designed and built by the University of Leicester for the joint European Space Agency/Japanese Space Agency mission BepiColombo.
This mission launched for the planet Mercury in October 2018, and will fly past the Earth, then Venus twice, then Mercury six times, before finally being inserted into orbit around the planet Mercury. Mercury is one of the hardest planets to orbit, not because it's difficult to get there, but because when you get so close to the Sun, it's hard to stop! The complex orbital trajectory can be seen opposite (courtesy ESA).
Our instrument, MIXS, is designed to measure X-rays coming from Mercury's surface, generated by the interaction with solar X-rays. The properties of the X-rays will tell us in unprecedented detail what the surface of Mercury is made of. This is vital for studies of planetary formation and evolution, as well as understanding the wealth of information provided by the study of planetary features such as impact craters.
Mercury has no atmosphere so high energy particles accelerated in the magnetosphere that would usually hit the atmosphere and generate the aurorae (in the analogous situation at the Earth), instead impact the surface directly, causing it to emit x-rays. This was not what the planetary x-ray instruments were designed for, but we have mapped this emission using the MESSENGER instrument, and are now looking forward to the arrival of our instrument on board BepiColombo, to give us much improved, higher resolution data. Using these signatures, we can map the topology of the planetary magnetic field, and gain new understanding of some of the most extreme magnetospheric dynamics in the solar system.
For more info on the mission see the ESA website here
