Solar cell for BepiColombo during an
endurance test. It is exposed to a high
thermal load in vacuum using a special
infrared light source.
When vacuum technology was introduced to the solar
furnace at DLR’s Cologne site over 10 years ago, the DLR engineers
had a vision. After coming into contact with scientists at the DLR
Institute of Space Physics, the idea of using the solar furnace for
space experiments came to life. In the solar furnace, relatively large
areas are exposed to high levels of radiation, and the solar spectrum
can be quite closely reproduced. Other space simulation facilities,
however, allow irradiances of just a few solar constants and only use
lamps.
The first space experiment goes back to a collaboration
between the Planetary Sensor Systems section at the DLR Insti-
tute of Planetary Research and the Institute of Geology and
Mineralogy at the University of Cologne. The aim of this project
was to investigate the potential for acquiring oxygen through
thermal decomposition or pyrolysis of lunar rock – in this case
chondrules, spherules in meteorites, which were formed in the
solar protoplanetary nebula. The experiment showed that this
material could be melted using concentrated solar energy.
Once the capabilities of the solar furnace had been
successfully demonstrated in a smaller vacuum chamber, a
significantly larger chamber – more than one metre in diameter
– was procured and improved, giving way to more space
experiments.
Tests for the BepiColombo mission to Mercury
The chondrule oxygen experiment was followed by the
most extensive series of tests to date – for multiple components
of BepiColombo. This spacecraft is scheduled to fly to Mercury in
2015, where it will investigate the planet’s geological, magnetic
and atmospheric conditions. All previous ESA interplanetary
missions have been sent far from the Sun, so the technology has
always been exposed to very low temperatures. And this is the
specific challenge – BepiColombo is the first ESA mission to
deliver a spacecraft into a very hot region. Once in Mercury orbit,
the side of the satellite turned towards the Sun will be extremely
hot, while the opposite side will be extremely cold. The external
components of the spacecraft must be able to withstand around
space experiments
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Outer space in the lab
When the large vacuum chamber is moved out of the cellar of the solar furnace building and into the testing area, a
very special experiment is about to take place. What is under investigation is not related to renewable energy, but
rather has to do with space applications. Components for spaceflight have been tested at the DLR Solar Furnace in
Cologne for a decade and, since 2007, in the high-flux solar simulator as well. Why? Since the components to be
investigated will be subjected to space conditions in future, it makes more sense to use the Sun as the source of
energy, instead of fossil fuels or lamp arrays. In tests of individual components such as solar cells, insulation layers
or protective covers, this mostly involves the ability to resist the severe, prolonged thermal loads and exposure to
ultraviolet radiation that occur in space. The DLR researchers’ customers are European spacecraft manufacturers, such
as EADS Astrium in Toulouse, Thales Alenia Space and the European Space Agency, ESA.
Space experiments in the DLR Solar Furnace
Research with solar energy
A total of some 180 experiments have been carried
out in the solar furnace since it was commissioned
in 1994. The focus has been on solar chemistry
and materials research. Decomposition of waste
sulphuric acid, recycling of aluminium, solar produc-
tion of hydrogen and knowledge of the ageing
process of automotive paint are typical applications
for the research conducted outside the area of
renewable energy.
By Gerd Dibowski
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