Citizen science starts to reveal Lucy mission target, Orus
September 17, 2019

Citizen science starts to reveal Lucy mission target, Orus

Observations made with a telescope designed for citizen science has taken the first step in providing detailed information on a target asteroid for NASA’s Lucy mission. The findings were presented today at the EPSC-DPS Joint Meeting 2019 in Geneva by Dr Franck Marchis of the SETI Institute.

Orus is the fifth object that Lucy will visit during a circuitous tour of seven different asteroids. The mission is due for launch in 2021 and will fly past Orus, which is part of a group of primitive bodies known as the Trojans, in 2028. 

On 7th September 2019, a team from the Unistellar citizen science project flew to Oman and successfully observed an event known as an occultation, in which Orus passed in front of a star, blocking its light for a few seconds.

Measuring precisely the time that the star is hidden enables astronomers to estimate the diameter of the asteroid and other physical properties. This is the first time an Orus occultation has been observed successfully. Making multiple occultation measurements over the next few years will help the Lucy team to build up an accurate picture of Orus’s shape and rotation.

Marc Buie, an astronomer at Southwest Research Institute, provided the predicted path of the occultation using a combination of observations from the ESA space telescope Gaia, and ground-based facilities like PanSTARRS, as well as other robotic telescopes. A new occultation by Orus will be visible in Australia on 4th November of this year.

“Calculations based previous on our observations from Oman give a diameter of about 54.8 kilometres for Orus, which is in line with estimations. We don’t yet know much about Orus, such as its shape and whether it possesses one or several satellites. The observation has proved that our predictions of the orbit of Orus are accurate and we can now plan a campaign to make multiple occultation observations,” said Dr. Franck Marchis, a senior astronomer at the SETI Institute and Unistellar’s Chief Scientific Officer.

The Lucy mission will be the first spacecraft to study Jupiter’s Trojans – two loose groups of asteroids that orbit the Sun, with one group always ahead of Jupiter in its path, the other always behind. These primitive objects hold crucial information about the history of our Solar System. Because many uncertainties surround the targeted asteroids, NASA needs to understand their shape and trajectories, and therefore to improve the path of its $450 million spacecraft. Determining the shape and size of an asteroid will, for example, allow engineers to optimise the exploration schedule, and increase the science return generated by the mission.

The SETI Institute is partnering with the Unistellar, the start-up behind the eVscope digital telescope, to develop a citizen astronomy programme in response to NASA’s call to the astronomical community to contribute to its Lucy space mission. They plan to use a worldwide network of 2,500 eVscopes to observe occultations by Lucy targets to derive their size, shape, and determine the existence of companion asteroids.

Oman was the most favourable spot on Earth from which to observe the occultation.

“Everything worked perfectly at our station located near Khalil. We were able to capture a light-curve full of valuable information and we have demonstrated that this is do-able with the eVscope prototype,” said Dr Marchis. “We hope to work with observers all over the world to support the Lucy mission.”


The Orus asteroid occulting a star, in the middle of the screen. Credit: F Marchis/Unistellar/SETI Institute


Conceptual image of the Lucy mission. Credits:  NASA/SwRI

Science Contact

Franck Marchis
Co-founder & CSO at
Unistellar and Senior
Astronomer at SETI Institute
+1 510 599 0604

Media contacts

Anita Heward
EPSC Press Officer
+44 7756 034243

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DPS Press Officer

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SETI Institute
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Notes for Editors

EPSC-DPS Joint Meeting 2019
The 2019 Joint Meeting ( of the European Planetary Science Congress (EPSC) of the Europlanet Society and the Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) will take place at the Centre International de Conférences de Genève (CICG), Geneva, Switzerland, from Sunday 15 to Friday 20 September 2019. More than 1950 abstracts have been submitted and over 1500 planetary scientists from Europe, the US and around the world are expected to attend the meeting, making it one of the largest gatherings of planetary scientists held in Europe to date.
The EPSC-DPS Joint Meeting 2019 will be the third time that EPSC and the DPS Annual Meeting have been held together.
Follow: @europlanetmedia #EPSCDPS2019

The Europlanet Society, launched in September 2018, is an organization for individual and corporate members to promote the advancement of planetary science and related fields in Europe. The Society provides Europe’s planetary science community with a platform to exchange ideas and personnel, share research tools, data and facilities, define key science goals for the future, and engage stakeholders, policy makers and European citizens with planetary science. The Europlanet Society is the parent organisation of the European Planetary Science Congress (EPSC).
Europlanet Society website:
EPSC-DPSC 2019 Joint Meeting 2019 website:

The Division for Planetary Sciences (DPS), founded in 1968, is the largest special-interest Division of the American Astronomical Society (AAS). Members of the DPS study the bodies of our own solar system, from planets and moons to comets and asteroids, and all other solar-system objects and processes. With the discovery that planets exist around other stars, the DPS has expanded its scope to include the study of extrasolar planetary systems as well.

The AAS, established in 1899, is the major organization of professional astronomers in North America. The membership (approx. 7,500) also includes physicists, mathematicians, geologists, engineers, and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy. The mission of the AAS is to enhance and share humanity’s scientific understanding of the universe, which it achieves through publishing, meeting organization, education and outreach, and training and professional development.

About Unistellar
Unistellar is the start-up behind the eVscope, a unique, compact, and user-friendly digital telescope. Its light amplification technology allows users to observe galaxies, nebulae, and comets in unparalleled crisp and colorful detail. In partnership with the SETI Institute, the Unistellar eVscope also allows anyone to contribute to astronomical discoveries while observing.
The Unistellar eVscope received a CES Innovation Award in 2018 in the category Tech for a Better World and has been nominated for a SXSW 2019 Innovation Award. It has raised more than $3 million through crowdfunding, and more than 2,500 digital telescopes have already been preordered.

About the SETI Institute
Founded in 1984, the SETI Institute is a non-profit, multi-disciplinary research and education organization whose mission is to explore, understand, and explain the origin and nature of life in the universe and the evolution of intelligence. Our research encompasses the physical and biological sciences and leverages expertise in data analytics, machine learning and advanced signal detection technologies. The SETI Institute is a distinguished research partner for industry, academia and government agencies, including NASA and NSF.