New worlds await ESPRESSO
2017 August 24

The four VLT telescopes, at Paranal Observatory, in Chile. ESPRESSO will receive the joint light collected by all four telescopes. Credits: ESO/B. Tafreshi ( (Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) has completed all preliminary tests and will shortly be shipped to Chile for installation at the VLT. Credits: University of Geneva
Credits: ESO
Artist's impression of the five-Earth mass planet, Gliese 581 c, found with the HARPS spectrograph, which preceded ESPRESSO. With ESPRESSO it will be possible to detect planets with the same mass as Earth's. Credits: ESO
After nearly ten years of planning and construction, the ESPRESSO spectrograph, a high resolution instrument that will enable the discovery of exoplanets similar to our Earth, will now be installed at the Very Large Telescope (VLT), of ESO, in Chile. The Instituto de Astrofísica e Ciências do Espaço (IA1), for its strong participation in the consortium2, will have privileged access to the scientific exploitation of this instrument, which first data are expected to be gathered from mid-2018.

The ESPRESSO spectrograph will enable astronomers to decompose and analyse the light coming from stars and, with that information, to measure the speed at which the stars are approaching or moving away from us. With the level of precision of ESPRESSO, capable of measuring a change in speed smaller than one kilometre per hour, it will be possible to measure the movement induced in the star by the gravitational pull of a planet as small as our planet Earth. It will also make it possible to determine the mass of the planet. Moreover, it is expected that the data will enable, in some cases, the identification of chemical elements in the planet's atmosphere.

Having passed the preliminary tests in Europe, as announced by ESO on the 22nd of August, ESPRESSO is about to depart on its first lap in the course to discover new worlds, the Paranal Observatory, in Chile. It was the responsibility of the team led by IA to develop and install the optical system that collects the light gathered by each of the four telescopes of the VLT and takes it to the site where this spectrograph will be installed.

Nuno Cardoso Santos (IA and Universidade do Porto), one of the instrument's principal investigators, underlines the importance of IA being involved simultaneously in the definition of the scientific goals and in the development of instrumentation: “The team3 at IA will now participate, together with its partners in the consortium, in the scientific exploitation of ESPRESSO. In total, we will have available 273 nights of observation with the VLT!”

Pedro Figueira (IA and Universidade do Porto), member of the scientific team of the project, adds: “We participate as well, in a very active way, in the preparation of the observations. As an example, we are now responsible to define the catalogue of stars to be observed in the search of planets.”

However, ESPRESSO will not be solely committed to discovering exoplanets. Carlos Martins (IA and Universidade do Porto), also a member of the scientific team, says that IA is equally responsible for the definition of the primary targets in fundamental physics. “The stability of the ESPRESSO spectrograph, together with the possibility of combining light from the four VLT telescopes, will allow us to test, with unprecedented accuracy, the universality of physical laws in the early Universe and shed light on the enigma of dark energy,” says Carlos Martins.

The Portuguese technological component of the ESPRESSO project was developed in a partnership between IA and the Laboratório de Óptica, Lasers e Sistemas (Laboratory of Optics, Lasers and Systems, LOLS), a technology transfer unit of Faculdade de Ciências da Universidade de Lisboa (FCUL). Alexandre Cabral (IA and FCUL) says: “The arrival at the Paranal Observatory will be the capstone of eight years of work in an international consortium in which the Portuguese research and industry successfully revealed their value. While the door is about to be opened for the Science that will be made with ESPRESSO, we are already starting to design the next big spectrographs.”

Nuno Santos stresses this IA's participation in future instruments: “Along these years we had the opportunity to demonstrate that we are international partners of high standard to any other state-of-the-art project in the area of Space,” says Nuno Santos. “This has thus far opened us the doors to several other projects, including a very significant role in the HIRES4 project, a high resolution spectrograph that is planned for the forthcoming ELT5.”

  1. The Instituto de Astrofísica e Ciências do Espaço (Institute of Astrophysics and Space Sciences – IA) is the largest Portuguese research unit in space sciences and integrates researchers from the University of Lisbon and the University of Porto. The institute encompasses most of the field’s national scientific output and it was evaluated as Excellent in the last evaluation from the European Science Foundation (ESF). IA’s activity is funded by national and international funds, including Fundação para a Ciência e a Tecnologia (UID/FIS/04434/2013), POPH/FSE and FEDER through COMPETE 2020.
  2. ESPRESSO is being designed and built by a consortium consisting of: Astronomical Observatory of the University of Geneva and University of Bern, Switzerland; INAF-Osservatorio Astronomico di Trieste and INAF-Osservatorio Astronomico di Brera, Italy; Instituto de Astrofísica de Canarias, Spain; Instituto de Astrofisica e Ciências do Espaço, Universities of Porto and Lisboa, Portugal; and ESO.
  3. The IA team for ESPRESSO consists of Nuno Santos, Alexandre Cabral, Manuel Abreu, António Oliveira, Carlos Martins, Catarina Silva, David Alves, Fernando Monteiro, João Aguas, João Coelho, José Rebordão, Mahmoud Hayati, Manuel Monteiro, Pedro Figueira, Pedro Santos, Ricardo Gomes e Sérgio Sousa.
  4. HIRES (High Resolution Spectrograph) is an instrument targeted at the ELT and will observe, with great precision, individual objects in visible light and infrared. It will allow astronomers to search for traces of life through the analysis of the atmospheres of exoplanets, study the evolution of galaxies and identify the first generation of stars that were formed in the early Universe, or determine if the physical constants of the Universe changed over time.
  5. The ELT (Extremely Large Telescope) will have a mirror composed of 798 hexagons of 1.45 metres each, with a honeycomb structure, that together add up to 39.3 metres in diameter. It is foreseen that ELT will have enough precision to, for instance, analyse the atmospheres of exoplanets or to measure in real time the acceleration of the expansion of the Universe. Portugal, as a full member of ESO, is one of the partners in this project, contributing with 5.1 million euros until 2023, about 0.5% of the total cost of the telescope.

Science Communication Group

Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Fundação para a Ciência e a Tecnologia