Evolution of ices: From molecular cloud to ocean

Lead Research Organisation: University of Sussex
Department Name: Sch of Life Sciences

Abstract

Ices of various forms are found throughout our Milky Way Galaxy, from the large "molecular clouds" in which stars and planets form, in interstellar space, and in our own Solar System, on the surfaces of the Earth, the satellites of Jupiter and Saturn, on asteroids, and on comets. It is very likely that water was delivered to the Earth during its formative years by the impacts of comets and asteroids in the kind of event that exterminated the dinosaurs 60 million years ago. Furthermore, these impacting bodies carry organic material, which may have been crucial to the emergence of life on Earth: comets and asteroids bring life and death! This project will study how cosmic ice evolves, from the environments of embryonic stars, to the ices and even oceans in the Solar System. We will be using laboratory experiments, including the world's most powerful light source, the Diamond Light Source in Oxfordshire, to study how the ices change as they are exposed to simulated cosmic environments such as cosmic radiation and ultraviolet light. This work might give us a glimpse as to how life began on Earth.

Planned Impact

To engage with the global research community, we will disseminate the results of our work by timely publication of data, with interpretation, in high-impact peer-reviewed journals, and by oral presentation at high profile international workshops and conferences. In view of the inter-disciplinary nature of the project we will be reaching a far wider community than is customary for astronomical work, for example, the oceanographic and chemical physics communities.

We will set up a consortium website, to which the various institutional web sites will be linked; this page will be maintained at Keele. It will be the means by which those seeking to use data acquired in this project will be directed to the VAMDC repository (see Data Management Plan). The availability of data will where appropriate be announced in peer-reviewed papers in which the data are presented.

The participating institutions have strong and active public engagement and widening participation strategies, and this project has ample scope for engaging with these schemes. The early career researchers employed on this project will be given the opportunity to attend (for example) STFC and Royal Society training programmes on public engagement and media communications, and to engage with nationally and regionally organised activities such as the Institute of Physics' "Physics in the Field" festival. This will contribute to the professional development of the early career researchers, and sits well with the RCUK "Concordat for Engaging the Public with Research".

For this purpose we request £1k per annum per PDRA/PGR researcher to enable them to attend (i) professional development activities and (ii) appropriate events such as sixth form conferences, science festivals etc. These funds will also be used to cover the costs of CRB checking for researchers who will be working with school students and vulnerable adults.

We also request £10k to design and produce suitably tailored, mass- and professionally-produced full colour leaflets to highlight the project to school students and the general public.

In due course, as the project evolves, we anticipate that there will be scope for explicit funding for outreach and public awareness, and we will approach the STFC for funding at the appropriate time.

Publications

10 25 50
 
Description The most important outcome from this work is the development of a novel UV/visible reflection-absorption spectrometer that can be used to determine the refractive index, n, and thickness, d, of ice films in vacuum at cryogenic (~ 20 K) temperatures. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model the ultra-violet spectra of various regions of space. In order to make these models more accurate, values of the refractive index need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling.

The new spectrometer was designed, built and tested during the course of this funding and preliminary results were obtained for two aromatic molecules - benzene and toluene. These molecules were used as a test system for the new instrument, however the data obtained are also relevant to the UV-visible spectra of poly-cyclic aromatic hydrocarbons (PAHs). In particular, the data reported give detailed, wavelength dependent, refractive indices for these molecules in the solid phase for the first time. The results also show the difference in the refractive index of the amorphous and crystalline forms of the solid benzene and toluene ice.

In order to provide context to the UV-visible experiments, initial studies were also performed to investigate the adsorption and desorption of the small aromatic molecules, benzene and toluene, on a model dust grain surface (graphite). These experiments also studied the effect of water ice of the desorption and trapping of these molecules and an astronomical model was developed that shows the expected desorption behaviour of the molecules in different ice configurations. The particular aim of the model was to predict the different behaviour observed in different interstellar environments and hence to aid observations of these molecules in space.

Further experiments with the new uv-visible spectrometer involve determining the refractive indices of complex organic molecules that are found in various regions of space, with the initial target molecules being methyl formate. Preliminary data show very different results for the methyl formate in the amorphous and crystalline ice phases, which can be linked to the known structures of the methyl formate ice phases.
Exploitation Route The results of our infrared and temperature programmed desorption studies will be used by astronomers in various models of star and planet formation and of hot-cores. The refractive index measurements will be used widely in any situations where wavelength-dependent refractive index values are required, eg in model of photon dominated regions and in models of UV-induced reactions or uv-induced destruction of molecules in various astrophysical environments.
Sectors Education,Other

 
Description Electron irradiation of ices on Europa
Amount £26,137 (GBP)
Organisation University of Sussex 
Sector Academic/University
Country United Kingdom
Start 07/2018 
End 02/2019
 
Title New reflection-absorption UV-visible spectrometer 
Description A novel UV/visible reflection-absorption spectrometer has been developed for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external z-shift allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice have been recorded as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure and a value for n of 1.43 ± 0.07 was determined 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact Yet to be exploited 
 
Description Heriot Watt University 
Organisation Heriot-Watt University
Department School of Engineering & Physical Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution Joint design of new spectrometer; experiments performed by both parties
Collaborator Contribution Joint design of new spectrometer; experiments performed by both parties
Impact 1 publication in preparation
Start Year 2015
 
Description Brighton Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Presentation of Stars R Us exhibit at Brighton Science Festival 27, 28 Feb 2016
Year(s) Of Engagement Activity 2016