Public defence in Space Science and Technology, M.Sc.(Tech.) Henrik Kahanpää
M.Sc.(Tech.) Henrik Kahanpää will defend the thesis "On atmospheric pressure measurements and dust devils on planet Mars" on 5 January 2023 at 12 (EET) in Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering, in lecture hall AS2, Maarintie 8, Espoo, and online in Zoom. You can follow the defence via this link: https://aalto.zoom.us/j/69407222231
Opponent: Dr. Leslie K. Tamppari, Pasadena, California, USA
Custos: Prof. Esa Kallio, Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering
Thesis available for public display 10 days prior to the defence at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/
Public defence announcement:
It storms on Mars when the planet is closest to the Sun in its orbit. Although the atmospheric density on the planet’s surface is only about 2 % of that on the Earth, winds are able to lift mineral dust into the atmosphere. On the other hand, dust is suspended in the Martian atmosphere also when storms do not occur. Small-scale whirlwinds known as dust devils have been suggested to maintain this background dustiness. The dissertation of Henrik Kahanpää and related studies question this perception. In addition, the dissertation shows that a Finnish instrument is capable to measure the atmospheric surface pressure of another celestial body with an accuracy of about 0.5%.
Modeling planetary atmospheres has become an important research topic for two reasons. First, the threat of climate change has increased the need to model our planet's climate. Second, assessing the conditions of exoplanets, found outside our Solar System, requires understanding of the general processes of planetary atmospheres.
NASA's probes Phoenix and Curiosity, landed on Mars in 2008 and 2012, respectively, are equipped with barometric pressure instruments provided by the Finnish Meteorological Institute and based on the technology of the Finnish company Vaisala. In the dissertation, sources of uncertainty affecting the measurements of these instruments are investigated and compensation methods for the uncertainty sources are developed. The results have been utilized in the development of a similar pressure instrument for NASA's Perseverance rover. Comparison of the corrected Phoenix pressure measurements with the measurements of NASA's Viking landers reveals no significant change in the Martian climate between the 1970s and 2008.
Dust devils are convective vortices forming above ground warmer than the atmosphere. On Mars, dust devils can have diameters exceeding 1 km and heights surpassing 10 km, however typically they are much smaller. The modeling of the atmosphere requires information on these weather phenomena as they can lift dust from the planet’s surface, affecting atmospheric flows. Signs of Martian convective vortices are sought in the dissertation from the weather measurements of the Curiosity rover. The results indicate only a small fraction of these vortices being strong enough to lift dust. Indeed, according to recent studies also other small-scale weather phenomena, such as slope winds, may significantly impact the dustiness of the Martian atmosphere.
Contact information of doctoral candidate:
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