On July 5, 2016, at 5:18 am (CET), NASA’s Juno interplanetary probe will be inserted into orbit around Jupiter, after a journey of five years. The University of Liège (ULg) has two direct involvements in this major mission to further our knowledge of the Solar System: the Space Centre Liège provided a vital component of one of the instruments aboard the probe, and astrophysicists at ULg are among the few European official co-investigators on the mission.
Launched in August 2011 from Cape Canaveral, and having traveled nearly 3 billion kilometers during a five-year cruise (including a fly-by of Earth in 2013), Juno is about to commence a unique scientific mission that will last a year and a half.
On July 5, 2016, Juno’s main engine will fire to slow the probe down and insert it into orbit around Jupiter. The end of this 35-minute manoeuvre is particularly critical — the slightest mistake could plunge Juno into the atmosphere of Jupiter or bounce it off into the outer solar system. If successful, this will mark the start of science operations of the mission.
As the first mission to go into an elliptical orbit over Jupiter’s poles, Juno’s challenge is to explore unknown regions of the Jupiter’s magnetosphere. The gas giant, Jupiter, is the largest planet in our Solar System and has influenced its history. There are many questions about Jupiter. How was it created? What is it made of? What’s hidden below its swirling clouds? What’s its magnetic field? NASA’s Juno mission aims to answer these questions and others, which could explain aspects of our Earth and the appearance of life.
The dual role of the University of Liège
The University of Liège is directly involved in Juno in two ways. On the design side, one of the essential parts of the ultraviolet telescope on board the probe — the input mirror and the drive motor of the spectrograph (a “scan mirror UVS”) — was designed and tested by the Space Centre of Liège. Astrophysicists at the STAR (Space sciences, Technologies and Astrophysics Research) unit of the University of Liège are also involved in the scientific analysis of data from the mission, as members of the Laboratoire de Physique Atmosphérique et Planétaire (LPAP) are among the few European official co-investigator of the mission.
“Researchers from the University of Liège are primarily interested in the powerful auroras that appear at the poles of the giant planet,” says Denis Grodent, astrophysicist and director of the Atmospheric and Planetary Physics Laboratory. “The instruments on board the probe will explore the interior of Jupiter and its space environment in order to understand how this giant planet formed and, by extension, to find out more about the origins of the planets in our solar system as we know it today.”
The University of Liège is closely involved in other Jupiter observation missions.
Juno is the first probe entirely powered by solar panels to visit the outer solar system. However, it will receive massive doses of radiation that will limit the lifetime of its instruments and electronics to within two years. At the end of its mission, the spacecraft will be sent into Jupiter’s atmosphere to burn up, in order to eliminate any risk of contact with the planet’s potentially habitable moons, Ganymede and Europe.
By 2030, these icy bodies will be under investigation via two new missions to Jupiter: the ESA-led JUICE and NASA-led Europa. The University of Liège is again associated with two instruments, as well as the JUICE mission’s solar panels, which are currently undergoing testing at the Centre Spatial de Liège. Researchers in the STAR astrophysical research unit will be officially involved in both missions.
In addition, the ULg LPAP has obtained the green light from the Space Telescope Science Institute (STScI) for an observation programme of Jupiter’s auroras using the Hubble Space Telescope (HST). This is one of the biggest HST observation programs of the solar system (151 orbits) that has ever been accepted. It will run in support of the Juno mission. Denis Grodent is the head of the international team of the project, along with colleagues Bonfond Bertrand, Jean-Claude Gerard and Aikaterini Radioti.
The fifth planet out from the Sun, Jupiter contains more than twice the mass of all the other planets of the Solar System. Jupiter is a gas giant planet and has a huge magnetic field, and can be seen as the focus of a kind of miniature solar system, consisting of dozens of moons. The planet’s swirling cloud bands are punctuated by massive storms like the Great Red Spot, which has raged for hundreds of years.
Giant planets like Jupiter are considered cornerstones in the formation of the Solar System, as they were assembled early in the process. Moreover, their enormous mass has shaped the orbits of other objects (planets, asteroids, comets) within the planetary system.
Although the basic story of the origin of Jupiter has been reconstructed, important questions remain – including the amount of water in its composition, and therefore oxygen. This gas giant holds clues to the origin of the solar system.
About the Laboratoire de Physique Atmosphérique et Planétaire (LPAP)
The Laboratoire de Physique Atmosphérique et Planétaire (LPAP) of the University of Liege specialises in the study of UV auroral emissions from Jupiter and Saturn. It studies the origin of magnetospheric particles creating these auroral lights and their effects on atmospheric structure. These studies are based on data acquired by the Hubble Space Telescope (HST), the Galileo satellite (Jupiter) and Cassini (Saturn). The Laboratory is also involved in the mission Hisaki (JAXA), Juno (NASA) and the future JUICE Mission (ESA).
More about Jupiter’s auroras: http://reflexions.ulg.ac.be/cms/c_391269/en/spotlight-on-jupiters-aurorae
Images and videos
Images, videos and infos on the NASA websit : http://www.jpl.nasa.gov/news/press_kits/juno/
Scientific involvements in this project : www.europlanet-eu.org/juno-europe/