INVENT GmbH from Braunschweig constructs central CFRP components for the worldwide-unique balloon observatory Sunrise III

Following the successful missions Sunrise I (2009) and Sunrise II (2013), the third mission of the largest solar observatory to ever leave the Earth and head skywards is scheduled to start in two years – in June 2022. The core component of Sunrise is a telescope, carried by a giant helium balloon, which will take off from the Kiruna high-altitude research airfield in Northern Sweden and will observe the Sun for around a week during its journey towards Northern Canada. The observatory will be “powered” by the polar winds. Shortly before landing, the balloon and the gondola will separate and a parachute will bring the telescope back to Earth.

The primary mirror in its supporting structure

INVENT GmbH from Braunschweig, Germany, which specializes in innovative lightweight construction, produced the so-called primary structures for the Sunrise telescope from carbon fibre-reinforced composites (CFRP) and has also delivered these structures for the third Sunrise mission. “The special challenge we faced during the preparation was not only to rework or replace the components previously manufactured for the first missions but also to achieve the same stiffness in the new convolute structures. This is because our major contribution to the telescope with regard to precise mirror alignment is the so-called CFRP Serrurier truss. This truss, named after the American engineer Mark Serrurier, connects the supporting structures of the primary and secondary mirrors,” explains Stefan Steeger, Sunrise Project Manager at INVENT, and adds: “It is wonderful to be able to accompany the life of the product within a single order. With Sunrise III, our departments have proven their expertise in testing techniques, fibre-composite production, and painting technology for both new production and the maintenance of existing parts.”  

The Sunrise III balloon observatory is intended to make “small” structures of up to 35 kilometres visible on the Sun and, amongst other things, to address the question of how solar magnetic fields influence these structures. For this purpose, the telescope must be able to constantly align itself with the Sun, independently and precisely – because if it is tilted, not enough heat can be dissipated and the telescope will be destroyed.

The Sun is about 150 million kilometres away from the Earth. Without its rays, the Earth would be devoid of life. The Sun also determines our day-night rhythm. “In addition, the Sun is highly dynamic and active – it makes things bubble, bang and bluster – with consequences which can lead to power outages for us or the paralysis of satellites,” explains Stefan Steeger. The Sunrise observatory is designed for use in the stratosphere: It floats above the Earth’s atmosphere and can therefore also investigate – unfiltered – the UV sunlight that is of interest to scientists. Furthermore, Sunrise can observe the Sun for several days, without interruption, during the summer solstice in June. In contrast to a space mission, the telescope with its measuring instruments can be salvaged, repaired or upgraded following the flight and subsequently re-launched.

Integration of a supporting structure


Passion for Composites

As a recognized lightweight construction specialist for innovative fibre composite technologies in the aerospace, mechanical engineering and automotive industries, INVENT GmbH in Braunschweig has been developing high-precision structural components, from the first idea to series production since 1996. INVENT’s designers and engineers work very closely together with in-house production specialists from the most diverse sectors. We are therefore able to offer our customers a complete package from a single source with regard to design, production planning, manufacturing processes, machining, joining and assembly as well as coating/painting and quality control.


On two occasions – in June 2009 and June 2013 – an international consortium led by the Max Planck Institute for Solar System Research (MPS) in Göttingen has already successfully studied the Sun for six days at a time, by means of the worldwide-unique solar observatory Sunrise: According to the MPS, more than 100 publications have so far been published in peer-reviewed journals. Sunrise is a total of six metres wide and seven metres high and weighs two tonnes. The observatory consists of a gondola, the telescope, a power supply and communication system, two scientific instruments and a landing and damping system. Three instruments are scheduled to fly on board Sunrise III in June 2022. The aim of the new mission is once again to study the fundamental physical processes of the magnetic field and plasma flows in the lower solar atmosphere. These processes are crucial for obtaining a better understanding of the Sun’s magnetic activity. They also regulate the transport of energy from the Sun’s interior to its outer layers, where the energy is released into space in the form of eruptions and coronal mass ejections, which in turn affect the Earth.

Fig. 1 Image taken by a camera during the balloon flight of Sunrise II [Source: MPS]

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