Lead Research Organisation: Open University
Department Name: Faculty of Sci, Tech, Eng & Maths (STEM)


ARIEL (the Atmospheric Remote-sensing Infrared Exoplanet Large-survey) has been selected by the European Space Agency (ESA) as the next medium class science mission (M4), expected to be launched in 2028. The mission will be devoted to performing spectroscopy, in which the optical and infrared light is spread into its component colours, or wavelengths to use the scientific term. Spectroscopy allows us to determine the chemicals present in an exoplanet atmosphere. ARIEL will observe a large and diverse population of exoplanets in our nearby Galactic neighborhood, revealing what they are made of, and enabling the understanding of the physics and chemistry of these far away worlds.

ARIEL is based on a 1 m class telescope feeding two instruments: a moderate resolution spectrometer covering the wavelengths from 1.95 to 7.8 microns; and a three channel photometer (which also acts as a fine guidance sensor) with bands between 0.5 and 1.2 microns combined with a low resolution spectrometer covering 1.2 to 1.95 microns. It will travel to the second Lagrangian point of the Earth-Sun system, i.e. in the direction of Earth's shadow at a place where there is a special gravitationally stable point. This point is often abbreviated as "L2". During its four years of operation, ARIEL will continuously observe exoplanets passing across the face of their host star. The target sample will include rocky and gaseous planets around a range of host star types. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk and elemental composition (especially C, O, N, S, Si). Observations of these warm/hot exoplanets will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star.

The ARIEL Phase-B study is currently ongoing and will end in late 2020. Assuming the study finds no show-stopping problems, ARIEL is forseen to be adopted by ESA in November 2020. ARIEL is a UK-led mission, and the work we will do funded by this grant will help UK scientists to make sure the mission delivers the best possible new science. This proposal will enable the UK science team, led by UCL and OU: Prof. Tinetti and Prof. Haswell, the UK appointed members of the Science Advisory Team (ESA-SAT). They will complete the Phase B study, and maintain the scientific leadership in the ARIEL international consortium.

Planned Impact

Industrial return - There are a number of items for which the UK ARIEL team is already engaged with UK industry teams. The items that are already within our planning are:
* Industrialisation and space qualification of tactical cooler compressors (e.g Hymatic, Exotec)
* One of our key goals is to get UK industry (e.g. Airbus, TAS-UK) as prime contractor for ARIEL or to provide a significant part of the spacecraft system

Discussions will continue in Phase B to iterate on possible workpackages for UK industry as a way to leverage UKSA investment in the payload in order to maximize the UK industrial return from the S/C contract. Haswell is a Redcar Ambassador, and is developing a network of contacts on Teesside with the aim of promoting and invigorating the fledgling high-tech and space industry there. These contacts include the prime movers behind The Digital City (see Teesside is currently economically deprived, but has a strong industrial heritage and a pool of under-utilised talent.

Outreach - The discovery of over 4000 extrasolar planets in the last couple of decades is probably one of the most exciting developments of modern astronomy. It resonates enormously with a public that has already been shown to have high interest levels in the exploration of the diverse worlds of our own Solar System, and an insatiable hunger for news about space exploration. It directly addresses deep philosophical issues that concern our fellow citizens: what are other worlds like? how do they form and evolve? Are we alone in the universe? So that means that public outreach that aims to engage our fellow citizens with the excitement of ARIEL and its science objectives will be at the forefront of our planning. The Open University has recently launched a free course "An Introduction to Exoplanets" ( which was conceived and produced by Haswell as lead academic. This course provides a roughly GCSE-level introduction to the scientific field of ARIEL, including transit spectroscopy.

An excellent way to engage and motivate the public is to provide access to data. The public will be invited to participate in the science exploitation of the ARIEL mission through access to data sets, taking advantage of the networks developed by very successful citizen science programs such as the Zooniverse/Planet Hunters team using Kepler data [Zooniverse website], and Solar Stormwatch [Solar Stormwatch website].

Attracting the Next Generation of Scientists, Engineers, forming future leaders - the UK future economy and competitiveness depends on strong science and engineering sectors. The promotion of observational and space sciences is crucial to inspire development of the next generation of scientists and engineers. Extrasolar planets are today one of the most trendy subjects, inspiring young people to take up the (physical) sciences in later studies and in their careers. The number of students choosing this field of research is increasing almost exponentially. The ARIEL team will work actively at promoting gender-balance and racial balance in science and engineering, inspiring young female and BAME students to choose STEM subjects at A-level and higher education and to widen participation at universities from underrepresented communities. The Open University has an explicit widening participation remit, and a 50-year track record.


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Charnay Benjamin (2021) A survey of exoplanet phase curves with Ariel in arXiv e-prints

Description Redcar | Cleveland Ambassadors
Geographic Reach Local/Municipal/Regional 
Policy Influence Type Influenced training of practitioners or researchers
Impact presented at "Building Bridges" event organised by Redcar and Cleveland district council. Liaised with local policy makers, influences, educators and industry leaders. Appeared on Zetland FM Community radio.
Title ARIEL target selection 
Description I am contributing to the discovery and characterisation of suitable hot, transiting exoplanets for observation by ARIEL 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact The ARIEL mission will be able to perform transmission spectroscopy on low mass rocky planets due to the large-scale-height gas distributions surrounding the Dispersed Matter Planet Project discoveries. 
Description ARIEL Phase curve working group 
Organisation Observatory of Paris
Country France 
Sector Academic/University 
PI Contribution I participated in collective report writing, and designing a potentially game-changing observational strategy exploiting the unprecedented stability the ARIEL telescope and instrumentation should deliver
Collaborator Contribution Collectively we have written a comprehensive report and presented at the ARIEL Open Conference. These inputs will for the basis of sections of the ESA "Red Book"
Impact Collectively we have written a comprehensive report and presented at the ARIEL Open Conference. These inputs will for the basis of sections of the ESA "Red Book"
Start Year 2019
Description ARIEL exoplanetary mass working group 
Organisation University of Porto
Country Portugal 
Sector Academic/University 
PI Contribution Dr John Barnes, PDRA on this grant, performed simulations of radial velocity observations of the full ARIEL target list (provisional) to assess how much ground-based radial velocity telescope time would be required to determine masses to a variety of precision thresholds. The planet mass can be used as an input to the atmospheric modelling, removing degeneracies in the fitting of the ARIEL spectroscopy. Hence this parameter can play a key role in increasing the robustness of the inferences regarding the atmospheric chemistry. I made key strategic inputs, pointing out that the required telescope time is reduced enormously if observations are made at the quadrature points of the planetary orbit when the radial velocities pass through their extrema (assuming a circular or near-circular) orbit.
Collaborator Contribution A variety of alternative complementary work has been done by partners
Impact A report of the working group which will form the basis for sections of the ARIEL Red Book
Start Year 2019
Description ARIEL high speed photometry working group 
Organisation Gothard Astrophysical Observatory
Country Hungary 
Sector Academic/University 
PI Contribution I have added scientific expertise, particularly on very close-orbiting disintegrating rocky exoplanets. I presented on behalf of this working group at the Royal Astronomical Society specialist meeting on "high precision photometry for exoplanet and time-domain astronomy" which took place on 8 Nov 2019
Collaborator Contribution a draft report to the ARIEL SAT considering the many pioneering scientific possibilities made possible by the mission's excellent photometric precision and stability
Impact presentations at conferences, draft report
Start Year 2019
Description Conference Organising Committee "ARIEL: Science, Mission, Community" 
Organisation European Space Agency
Department European Space Research and Technology Centre (ESTEC)
Country Netherlands 
Sector Public 
PI Contribution I served on the scientific organising committee for this conference in January 2020, which aimed to bring together the European and international exoplanet research community to discuss the ARIEL mission and plan to maximise its scientific output. I participated in planning the programme, chaired the opening session, gave a presentation and engaged in many fruitful formal and informal discussions. ESA undertook to pay my expenses
Collaborator Contribution ESA provided the venue and logistical support. Othe members of the SOC made similar contributions to my own.
Impact Dozens of cutting edge scientific presentations linked from the URL below disciplines: aerospace engineering, planetary science, astrophysics, artificial intelligence, data science
Start Year 2019
Description ESA's ARIEL Mission Science Advisory Team 
Organisation European Space Agency
Department European Space Research and Technology Centre (ESTEC)
Country Netherlands 
Sector Public 
PI Contribution I am a European Space Agency (ESA) appointee to this oversight committee. I have attended committee meetings and participated in the collective decision-making by teleconferences, email, and face to face discussions. I am responsible for authoring several sections in the ESA "Red Book" document which will be used by the ESA advisory committee structure to assess the ARIEL mission. This work is critical for ESA's pending decision to adopt ARIEL (or not); once a mission is adopted large sums of money are committed to building the hardware and developing the necessary supporting infrastructure.
Collaborator Contribution Partners on the committee made similar contributions to my own. We each bring unique perspectives and our own particular scientific expertise.
Impact The ARIEL SAT has a combination of planetary science, astrophysics and aerospace engineering expertise. The primary output was the ESA Redbook. I also served on a sub-committee which wrote the Ariel Science Management Plan. These documents played a significant role in the adoption of Ariel by ESA.
Start Year 2018
Description North Yorks Moors Dark Skies Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact I organised and ran two evening events at the northern edge of the North Yorks Moors national park. These were designed to engage the under-served audiences on Teesside. The largest group of participants were a group of 40 (25 children and 15 teachers, parents and carers) from Brambles Primary Academy in Middlesbrough a school where half of all pupils qualify for pupil premium. The community associated with the school are in the top 1% for deprivation nationally.
Year(s) Of Engagement Activity 2020