|[Published: Monday October 08 2018]
Launch of BepiColombo unraveling the mysteries of Mercury
PARIS, 08 Oct. - (ANA) - BepiColombo – ESA-JAXA mission to Mercury- is scheduled to launch aboard an Ariane-5 from Europe’s Spaceport in Kourou, French Guiana at 01:45 GMT (03:45 CEST) on 20th October 2018.
BepiColombo is the first European mission to Mercury, the smallest and least explored planet in the inner Solar System.
BepiColombo is a joint endeavour between ESA and the Japan Aerospace Exploration Agency, JAXA, and consists of two scientific orbiters: ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO).
The mission will study all aspects of Mercury, from the structure and dynamics of its magnetosphere and how it interacts with the solar wind, to its internal structure with its large iron core, and the origin of the planet’s magnetic field. It will make global maps of the surface elemental and chemical composition and take images of features to better understand geological processes and how the surface has been modified over time by impact craters, tectonic activity, volcanism and polar ice deposits.
The data will enable scientists to understand more about the origin and evolution of a planet located close to its parent star, and a better understanding of the overall evolution of our Solar System.
The ESA-built Mercury Transfer Module (MTM) will carry the orbiters to Mercury using a combination of solar electric propulsion and gravity assist flybys. Over seven years, the mission will make one flyby of Earth, two at Venus, and six at Mercury. Once arriving in Mercury’s gravity, the MPO will use its thrusters to bring the MMO to the right orbit. They will then separate, and the MPO will use its thrusters once again to take itself to the closer orbit. The two orbiters will then make complementary observations of various aspects of the planet.
The mission builds on the scientific heritage of NASA’s Mariner 10 flyby mission in 1974-75, and Messenger, which orbited the planet from 2011 to 2015. One obvious difference between these missions is that BepiColombo comprises two spacecraft in different orbits, affording new science possibilities. In particular, dual observations are key to understanding solar-wind-driven magnetospheric processes, and this will allow unparalleled observations of the planet’s magnetic field and the interaction of the solar wind with the planet at two different locations at the same time.
The BepiColombo spacecraft and their suite of instruments will provide the best understanding of Mercury to date, following up on many of the mysteries highlighted by Messenger. These include specific details of the planet’s interior and magnetic field, to unique surface features identified – including water-ice in permanently shadowed polar craters. The MPO will make global maps of the surface chemistry and features to better understand geological process and how the surface has been modified through time by impact craters, tectonic and volcanic activity.
To enable this mission to cope with the high temperatures that will be experienced close to the Sun– more than 350ºC – specific technologies had to be developed, including high-temperature protective coatings and multi-layered insulation. The MPO is equipped with a large radiator to carry away heat generated by the spacecraft subsystems and instruments, as well as from the Sun and reflected from Mercury’s surface.
JAXA’s MMO is a spin-axis stabilised spacecraft, ensuringthat the ‘top’ and ‘bottom’ of the spacecraft are never Sun-pointed. Each of the eight side panels is fitted with solar cells, with the areas not covered instead equipped with a mirror finish to reflect solar radiation. During the cruise phase it won’t be spinning, so it is thermally protected by a sunshield and interface structure fixed to the MMO, which will be discarded once arriving at Mercury.
The MPO solar array will face the Sun almost edge-on in order to not be damaged by the fierce solar radiation. Despite travelling towards the Sun the MTM requires a large solar array: its two wings span about 30 m tip-to-tip when fully deployed, together totaling 42 m2. Because of the high solar intensity they cannot directly face the Sun without reaching excessively high temperatures, so they instead have to be rotated away from the Sun and therefore still need a large area to meet the power requirements of the spacecraft.
Another challenge for the mission is the Sun’s enormous gravity, which makes it difficult to place a spacecraft into a stable orbit around Mercury – even more energy is needed than sending a mission to Pluto. After launch, and having escaped the ‘gravity well’ of Earth, BepiColombo has to constantly brake against the gravitational pull from the Sun. Ion thrusters on the MTM will provide this constant low thrust over long durations of the cruise phase. Ion thrusters have been used and demonstrated previously in ESA’s SMART-1 mission to the moon.
BepiColombo is the result of major international cooperation, with ESA being responsible for the overall mission design:
-Airbus Defence and Space in Germany is the prime contractor for the design and procurement of the ESA parts of the spacecraft, including MPO, MTM, MMO’s sunshield, and the interface between MPO and MMO. Furthermore, it provided the design and development of the data management, attitude and orbit control subsystems, and solar arrays.
-Thales Alenia Space Italy is the co-prime contractor for the development of the MPO’s electrical power, thermal control and communications systems and for the integration and test activities.
-In the UK, Airbus Defence and Space is co-prime contractor for the electrical and chemical propulsion systems, for the structure of all modules and for the thermal control of MTM. Airbus Defence and Space in France has developed the onboard software.
-MMO was designed and developed by JAXA, who in turn was responsible for procuring the spacecraft from an industrial team led by NEC Corporation.
The mission is named after the Italian mathematician and engineer Giuseppe (Bepi) Colombo (1920–84). He is known for explaining Mercury’s peculiar characteristic of rotating about its own axis three times in every two orbits of the Sun. He also proposed to NASA the interplanetary trajectories that would allow Mariner-10 multiple Mercury flybys, by using gravity assists at Venus for the first time. - (ANA) -
AB/ANA/ 08 October 2018 - - -