On atmospheric pressure measurements and dust devils on planet Mars

Henrik Kahanpää

On atmospheric pressure measurements and dust devils on planet Mars

Julkaisun otsikon käännös: Mars-planeetan kaasukehästä, sen paineen mittauksista ja pölypyörteistä

Henrik Kahanpää

Elektroniikan ja nanotekniikan laitos

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Planeettojen kaasukehien mallinnus on noussut merkittäväksi tutkimusaiheeksi kahdesta syystä.Ensinnäkin ilmastonmuutoksen uhka on lisännyt tarvetta mallintaa oman planeettamme ilmastoa.Toiseksi oman aurinkokuntamme ulkopuolelta löytyneiden planeettojen olosuhteiden arvioiminen edellyttää ymmärrystä planeettojen kaasukehien yleisistä prosesseista. Mars-planeetan kaasukehässä leijailee suuri määrä mineraalipölyä, vaikka kaasukehän keskimääräinen tiheys pinnalla on vain noin 2 % Maan ilmakehän pintatiheydestä. Koska pöly absorboi saapuvaa ja lähtevää säteilyä, kaasukehän dynamiikan mallintaminen edellyttää niiden prosessien tuntemusta, jotka nostavat pölyä pinnalta kaasukehään. Pienen mittakaavan pölypyörteet ovat yksi näistä prosesseista. Tämä väitöskirja vastaa kahteen Marsin kaasukehän mittaamiseen ja mallintamiseen liittyvään haasteeseen: planeetan pinnalla mitatun ilmanpaineaineiston laadun parantamiseen sekä pölypyörteiden ilmastollisen vaikutuksen tutkimiseen ilmanpaineaineiston avulla. Perättäisten Mars-laskeutujien tarkkojen ja jäljitettävien ilmanpainemittausten ansiosta on mahdollista tutkia myös planeetan ilmaston hitaita muutoksia. NASAn Phoenix Mars-laskeutujan sekä Mars Science Laboratory (MSL) ja Mars 2020 -kulkijoiden ilmanpainemittalaitteet perustuvat Vaisala Oyj:n valmistamiin Barocap®-antureihin. Näitä antureita on lisäksi käytetty useissa epäonnistuneissa Mars-laskeutujissa ja niitä suunnitellaan käytettäväksi myös tulevissa laskeutujissa. Tässä työssä selvitetään Barocap®-antureihin pohjautuvien Marsin ilmanpaineen mittauksien epävarmuustekijöitä tutkimalla mittalaitteiden alkuperäisiä testiaineistoja, analysoimalla avaruuslentojen aikana kerättyjä teknisiä mittaustietoja ja testaamalla referenssimalleja laboratoriossa. Johtopäätös on, että Marsin kaasukehän pintapaine voidaan mitata Barocap®-antureiden avulla paremmalla kuin 3 Pascalin tarkkuudella mikäli kaikki mahdolliset virhelähteet selvitetään ja kompensoidaan. Pölypyörteiden ja muiden pyörretuulien aiheuttamia signaaleja etsitään tässä työssä MSL kulkijan meteorologisesta mittausaineistosta. Tilastoja havaituista pyörretuulista verrataan numeerisen ilmastomallin ennusteisiin. Lisäksi pyörretuulien dynamiikkaa tutkitaan sovittamalla matemaattista pyörremallia MSL-kulkijan tuuli- ja painemittauksiin. Tämä tutkimus on ensimmäinen laatuaan, sillä ilmanpainetta ja tuulta ei ole aiemmin mitattu Marsissa yhtäaikaisesti riittävällä erotuskyvyllä. Väitöskirjatyön tulokset osoittavat, että nykyiset menetelmät sen pölymäärän laskemiseksi, jonka pölypyörteet nostavat Marsin kaasukehään, johtavat tämän pölymäärän alueellisen ja ajallisen vaihtelun aliarvioimiseen. Realistisemmassa menetelmässä tulisi mallintaa pyörretuulien voimakkuusjakauma sekä ottaa huomioon pölypyörteen voimakkuuden vaikutus sen kykyyn nostaa pölyä.

Julkaisun otsikon käännös	Mars-planeetan kaasukehästä, sen paineen mittauksista ja pölypyörteistä
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Kallio, Esa, Vastuuprofessori Schmidt, Walter, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-64-1070-8
Sähköinen ISBN	978-952-64-1071-5
Tila	Julkaistu - 2022
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

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@phdthesis{6c0820deed314f79a78f4480e5f8795f,

title = "On atmospheric pressure measurements and dust devils on planet Mars",

abstract = "The modeling of planetary atmospheres has become an increasingly important research topic for two reasons. First, the threat of climate change has increased the need for modeling the climate of our planet. Second, assessing the conditions of planets found outside our Solar System requires an understanding of the general processes of planetary atmospheres. High amounts of mineral dust are suspended in the atmosphere of planet Mars even if the mean atmospheric density at the surface is only about 2% of that on the Earth. As dust absorbs incoming and outgoing radiation, modeling the dynamics of the planet's atmosphere requires information on the processes which lift dust from the surface. Small-scale whirlwinds known as dust devils are one of those processes. This thesis work responds to two challenges related to the measurement and modeling of the Martian atmosphere: to improve the quality of barometric pressure measurements and to study the effect of dust devils on the atmosphere using the pressure data. Accurate and traceable pressure measurements by several successive Mars landers also enable studying slow changes in the Martian climate. The barometric pressure devices of NASA's Mars lander Phoenix and the rovers Mars ScienceLaboratory (MSL) and Mars 2020 are based on Barocap{\textregistered} sensor heads manufactured by the Vaisala Company. Furthermore, these sensor heads have been used in several failed Mars landers and are planned to be used in several upcoming landers. In this thesis work, sources of uncertainty affecting Barocap{\textregistered}-based pressure measurements on Mars are investigated through the analysis of the original test data of the devices, the analysis of the engineering data collected during past missions in space, and the laboratory tests with reference models. We conclude that the surface pressure of Mars can be measured using Barocap{\textregistered} sensors with an accuracy better than 3 Pascal, however it requires careful examination of and compensation for all possible error sources. Signs of dust devils and similar vortices not lifting dust are sought in this work from the time series of meteorological variables collected by the MSL rover. The statistics of the identified vortices are compared to forecasts from a numerical climate model. The dynamics of dust devil -like vortices are also studied by fitting a mathematical vortex model to the wind and pressure measurements of MSL, a first-of-its-kind study because previous Mars landers have not measured both pressure and wind simultaneously with adequate resolution. Our results show that the current schemes for calculating the amount of dust raised into the Martian atmosphere by dust devils lead to underestimating the spatial and seasonal variation in dust lifting. A more realistic scheme would require evaluating the distribution of vortex strengths and considering that the dust lifting capacity of a dust devil depends on its strength.",

keywords = "space technology, planetary science, Mars, meteorological instrumentation, atmospheric modelling, dust devils, space technology, planetary science, Mars, meteorological instrumentation, atmospheric modelling, dust devils",

author = "Henrik Kahanp{\"a}{\"a}",

year = "2022",

language = "English",

isbn = "978-952-64-1070-8",

series = "Aalto University publication series DOCTORAL THESES",

publisher = "Aalto University",

number = "193",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - On atmospheric pressure measurements and dust devils on planet Mars

AU - Kahanpää, Henrik

PY - 2022

Y1 - 2022

N2 - The modeling of planetary atmospheres has become an increasingly important research topic for two reasons. First, the threat of climate change has increased the need for modeling the climate of our planet. Second, assessing the conditions of planets found outside our Solar System requires an understanding of the general processes of planetary atmospheres. High amounts of mineral dust are suspended in the atmosphere of planet Mars even if the mean atmospheric density at the surface is only about 2% of that on the Earth. As dust absorbs incoming and outgoing radiation, modeling the dynamics of the planet's atmosphere requires information on the processes which lift dust from the surface. Small-scale whirlwinds known as dust devils are one of those processes. This thesis work responds to two challenges related to the measurement and modeling of the Martian atmosphere: to improve the quality of barometric pressure measurements and to study the effect of dust devils on the atmosphere using the pressure data. Accurate and traceable pressure measurements by several successive Mars landers also enable studying slow changes in the Martian climate. The barometric pressure devices of NASA's Mars lander Phoenix and the rovers Mars ScienceLaboratory (MSL) and Mars 2020 are based on Barocap® sensor heads manufactured by the Vaisala Company. Furthermore, these sensor heads have been used in several failed Mars landers and are planned to be used in several upcoming landers. In this thesis work, sources of uncertainty affecting Barocap®-based pressure measurements on Mars are investigated through the analysis of the original test data of the devices, the analysis of the engineering data collected during past missions in space, and the laboratory tests with reference models. We conclude that the surface pressure of Mars can be measured using Barocap® sensors with an accuracy better than 3 Pascal, however it requires careful examination of and compensation for all possible error sources. Signs of dust devils and similar vortices not lifting dust are sought in this work from the time series of meteorological variables collected by the MSL rover. The statistics of the identified vortices are compared to forecasts from a numerical climate model. The dynamics of dust devil -like vortices are also studied by fitting a mathematical vortex model to the wind and pressure measurements of MSL, a first-of-its-kind study because previous Mars landers have not measured both pressure and wind simultaneously with adequate resolution. Our results show that the current schemes for calculating the amount of dust raised into the Martian atmosphere by dust devils lead to underestimating the spatial and seasonal variation in dust lifting. A more realistic scheme would require evaluating the distribution of vortex strengths and considering that the dust lifting capacity of a dust devil depends on its strength.

AB - The modeling of planetary atmospheres has become an increasingly important research topic for two reasons. First, the threat of climate change has increased the need for modeling the climate of our planet. Second, assessing the conditions of planets found outside our Solar System requires an understanding of the general processes of planetary atmospheres. High amounts of mineral dust are suspended in the atmosphere of planet Mars even if the mean atmospheric density at the surface is only about 2% of that on the Earth. As dust absorbs incoming and outgoing radiation, modeling the dynamics of the planet's atmosphere requires information on the processes which lift dust from the surface. Small-scale whirlwinds known as dust devils are one of those processes. This thesis work responds to two challenges related to the measurement and modeling of the Martian atmosphere: to improve the quality of barometric pressure measurements and to study the effect of dust devils on the atmosphere using the pressure data. Accurate and traceable pressure measurements by several successive Mars landers also enable studying slow changes in the Martian climate. The barometric pressure devices of NASA's Mars lander Phoenix and the rovers Mars ScienceLaboratory (MSL) and Mars 2020 are based on Barocap® sensor heads manufactured by the Vaisala Company. Furthermore, these sensor heads have been used in several failed Mars landers and are planned to be used in several upcoming landers. In this thesis work, sources of uncertainty affecting Barocap®-based pressure measurements on Mars are investigated through the analysis of the original test data of the devices, the analysis of the engineering data collected during past missions in space, and the laboratory tests with reference models. We conclude that the surface pressure of Mars can be measured using Barocap® sensors with an accuracy better than 3 Pascal, however it requires careful examination of and compensation for all possible error sources. Signs of dust devils and similar vortices not lifting dust are sought in this work from the time series of meteorological variables collected by the MSL rover. The statistics of the identified vortices are compared to forecasts from a numerical climate model. The dynamics of dust devil -like vortices are also studied by fitting a mathematical vortex model to the wind and pressure measurements of MSL, a first-of-its-kind study because previous Mars landers have not measured both pressure and wind simultaneously with adequate resolution. Our results show that the current schemes for calculating the amount of dust raised into the Martian atmosphere by dust devils lead to underestimating the spatial and seasonal variation in dust lifting. A more realistic scheme would require evaluating the distribution of vortex strengths and considering that the dust lifting capacity of a dust devil depends on its strength.

KW - space technology

KW - planetary science

KW - Mars

KW - meteorological instrumentation

KW - atmospheric modelling

KW - dust devils

KW - space technology

KW - planetary science

KW - Mars

KW - meteorological instrumentation

KW - atmospheric modelling

KW - dust devils

M3 - Doctoral Thesis

SN - 978-952-64-1070-8

T3 - Aalto University publication series DOCTORAL THESES

PB - Aalto University

ER -

On atmospheric pressure measurements and dust devils on planet Mars

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