Periodic Reporting for period 1 - SeisMo (SEismology of the MOon)
Période du rapport: 2016-02-01 au 2018-01-31
The project used seismic data from the Moon, using the seismometers installed by the Apollo astronauts.
Our work had four objectives:
- Provide the Apollo data in a modern format (SEED) for current and future users of the Apollo data.
- Determine an accurate model of the crust and upper mantle of the Moon using coda wave interferometry.
- Use highly accurate wave propagation simulation techniques to understand more about the structure of the moon and lunar seismograms.
- Investigate the use of portable rotational seismometers for future planetary missions.
Our work had four objectives:
- Provide the Apollo data in a modern format (SEED) for current and future users of the Apollo data.
- Determine an accurate model of the crust and upper mantle of the Moon using coda wave interferometry.
- Use highly accurate wave propagation simulation techniques to understand more about the structure of the moon and lunar seismograms.
- Investigate the use of portable rotational seismometers for future planetary missions.
1) Provide the Apollo data in a modern format (SEED) for current and future users of the Apollo data:
In order to run the cross-correlations (our second objective), we required the data in modern SEED format, and a better understanding of the timing on the seismic traces. We have written a paper to make this information available to the seismology community, and will make the data available to download from IRIS.
2) To determine an accurate model of the crust and upper mantle of the Moon using coda wave interferometry:
The coda is the later part of a seismic wave, which has been scattered multiple times before arriving at the seismometer. Coda wave interferometry uses seismic waves from the same event arriving at two different seismic stations. The waveforms are cross-correlated. Coherent energy travelling between the two stations is revealed by the cross correlation. The patterns were very different from those seen on Earth, and had little coherence. Future work will use simulations in strongly scattering media to simulate the cross-correlations, to understand more about what the cross-correlations reveal about the underlying structure of the Moon.
3) Use highly accurate wave propagation simulation techniques to understand more about the structure of the moon and lunar seismograms:
The lunar surface is very fractured. This results in seismic energy which is scattered in all directions. We are using the state-of-the-art modelling tool Salvus to model the lunar surface and understand what lies beneath the scattering layer. This work is ongoing.
4) Investigate the use of portable rotational seismometers for future planetary missions.
We explored new methods for future planetary missions. I co-authored a paper on the 'Benefits of rotational ground motions for planetary seismology'. We are also trialling a portable seismometer for a future mission to Jupiter’s moon Europa (see details below).
In addition, the following activities were carried out as part of the fellowship:
- Designed and supervised internships and Master’s Projects.
- Invited to collaborate with the NASA project Planetary Data Archiving, Restoration, and Tools (PDART).
- Invited to join the working group 'An International Reference for Seismological Data Sets and Internal Structure Models of the Moon’ at the International Space Science Institute. As a team we are working on two papers, 'Reference Lunar Seismological Datasets' and 'Reference Models for the Internal Structure of the Moon'.
- Attended Salvus workshop (Salvus is a new seismic modelling and inversion tool).
- Attended the TIDES (TIme-DEpendent Seismology) Training School in Oxford.
- Attended EGU Vienna, AGU San Francisco and AGU New Orleans.
- Attended German seismology conferences (A.G. Seismologie, 2016 and 2017).
- Built a website www.cerinunn.com/seismo.
- Made code available on GitHub https://github.com/cerinunn.
- Developed and presented two talks for primary school children. The talks were called 'The Moon’ and 'How to Build a Mountain'.
- Contributed material to SeismoLive (http://krischer.github.io/seismo_live/) a public resource for geophysics lecturers.
- Attended course at LMU (winter semester 2017/2018) to improve my German skills.
In order to run the cross-correlations (our second objective), we required the data in modern SEED format, and a better understanding of the timing on the seismic traces. We have written a paper to make this information available to the seismology community, and will make the data available to download from IRIS.
2) To determine an accurate model of the crust and upper mantle of the Moon using coda wave interferometry:
The coda is the later part of a seismic wave, which has been scattered multiple times before arriving at the seismometer. Coda wave interferometry uses seismic waves from the same event arriving at two different seismic stations. The waveforms are cross-correlated. Coherent energy travelling between the two stations is revealed by the cross correlation. The patterns were very different from those seen on Earth, and had little coherence. Future work will use simulations in strongly scattering media to simulate the cross-correlations, to understand more about what the cross-correlations reveal about the underlying structure of the Moon.
3) Use highly accurate wave propagation simulation techniques to understand more about the structure of the moon and lunar seismograms:
The lunar surface is very fractured. This results in seismic energy which is scattered in all directions. We are using the state-of-the-art modelling tool Salvus to model the lunar surface and understand what lies beneath the scattering layer. This work is ongoing.
4) Investigate the use of portable rotational seismometers for future planetary missions.
We explored new methods for future planetary missions. I co-authored a paper on the 'Benefits of rotational ground motions for planetary seismology'. We are also trialling a portable seismometer for a future mission to Jupiter’s moon Europa (see details below).
In addition, the following activities were carried out as part of the fellowship:
- Designed and supervised internships and Master’s Projects.
- Invited to collaborate with the NASA project Planetary Data Archiving, Restoration, and Tools (PDART).
- Invited to join the working group 'An International Reference for Seismological Data Sets and Internal Structure Models of the Moon’ at the International Space Science Institute. As a team we are working on two papers, 'Reference Lunar Seismological Datasets' and 'Reference Models for the Internal Structure of the Moon'.
- Attended Salvus workshop (Salvus is a new seismic modelling and inversion tool).
- Attended the TIDES (TIme-DEpendent Seismology) Training School in Oxford.
- Attended EGU Vienna, AGU San Francisco and AGU New Orleans.
- Attended German seismology conferences (A.G. Seismologie, 2016 and 2017).
- Built a website www.cerinunn.com/seismo.
- Made code available on GitHub https://github.com/cerinunn.
- Developed and presented two talks for primary school children. The talks were called 'The Moon’ and 'How to Build a Mountain'.
- Contributed material to SeismoLive (http://krischer.github.io/seismo_live/) a public resource for geophysics lecturers.
- Attended course at LMU (winter semester 2017/2018) to improve my German skills.
We reimported the data from the Apollo missions (the data cover the period from 1969-1977) into a modern format. The figure shows an example of the imported data. The data will be easy to access and download, and therefore available to a broader audience. The accompanying paper makes the limitations of the data clearer.
We are part of a project to assess seismometers for Jupiter’s moon Europa. We are trialling rotational seismometers, which measure the rotational part of the seismic wave. They can complement traditional seismometers, which measure the translational motion (up-down, north-south, east-west). We are also investigating using them on their own. We are sending a BlueSeis 3A, which is a portable seismometer made by the French company iXblue, to a site in Greenland. The seismometer has many potential advantages over a traditional seismometer. It does not include moving parts, and has space-grade fibre optics. This makes it very suitable for Europa’s high radiation environment. It also does not need levelling when it is deployed (it could be deployed upside-down if necessary). This makes it a much cheaper, lighter option than a traditional seismometer, since the levelling equipment for a planetary mission is both heavy and complicated.
The seismometer is also very suitable to be deployed on glaciers, and is potentially more robust than traditional seismometers. Because the glacier moves, a traditional seismometer can be tipped out of alignment in just a few weeks, and needs re-levelling. This problem does not affect the BlueSeis 3A. Seismology is used on glaciers to understand the structure, transport and fracture mechanics of the glacial ice, and is important for studying the effects of climate change.
If our trials are successful, there is a high potential for new jobs in science and manufacturing to develop the seismometers as part of a planetary mission or glacial seismology campaign.
We are part of a project to assess seismometers for Jupiter’s moon Europa. We are trialling rotational seismometers, which measure the rotational part of the seismic wave. They can complement traditional seismometers, which measure the translational motion (up-down, north-south, east-west). We are also investigating using them on their own. We are sending a BlueSeis 3A, which is a portable seismometer made by the French company iXblue, to a site in Greenland. The seismometer has many potential advantages over a traditional seismometer. It does not include moving parts, and has space-grade fibre optics. This makes it very suitable for Europa’s high radiation environment. It also does not need levelling when it is deployed (it could be deployed upside-down if necessary). This makes it a much cheaper, lighter option than a traditional seismometer, since the levelling equipment for a planetary mission is both heavy and complicated.
The seismometer is also very suitable to be deployed on glaciers, and is potentially more robust than traditional seismometers. Because the glacier moves, a traditional seismometer can be tipped out of alignment in just a few weeks, and needs re-levelling. This problem does not affect the BlueSeis 3A. Seismology is used on glaciers to understand the structure, transport and fracture mechanics of the glacial ice, and is important for studying the effects of climate change.
If our trials are successful, there is a high potential for new jobs in science and manufacturing to develop the seismometers as part of a planetary mission or glacial seismology campaign.