After 31 parabolas, each with 22 seconds of microgravity, the first of three flight days comes to an end. The team of scientists, volunteers
and pilots are more than satisfied with the research results of the 22nd DLR parabolic flight campaign.
responsible for the perception of gravity and where, for instance,
the calcium in its interior – the level of which rises dramatically
during periods of zero gravity – comes from. This is why 36
bottles full of cells are on board during the steep climb and
subsequent dive. A crop plant is also along for the ride to permit
comparisons with the weed; a Brazilian scientist is on hand to
look after the sugarcane cell cultures. Svenja Fengler now sits
motionless on the soft mats covering the floor. “Pull-out.” She
braces herself with one hand against the soft foam wrapped
around the edges of her equipment to protect the system.
Before the flight, a team of 12 safety officers thoroughly checked
each individual instrument one last time. Are there any stray
components that could just float off during zero gravity? Have
all the sharp edges been protected to make sure no one is hurt,
even during the transition to double gravity? Each of the experi-
ments has been fitted with a red emergency button. With just
one push the experiment will stop – a precautionary measure in
case electricity, X-rays or liquids are in danger of spiralling out of
control.
While the cell cultures are experiencing their first taste of
zero gravity, Hans Schlegel, an old hand at weightlessness, floats
through the cabin once more, just a few metres away. He flew
on the Spacelab D2 mission back in 1993, and delivered the Eu-
ropean research laboratory Columbus to the International Space
Station in 2008. “Your body always remembers weightlessness,”
he will say later, once the parabolic flight aircraft is safely back
on solid ground. But for now, he is entirely focused on what as-
tronauts are so familiar with – floating without fear.
Heartbeat by heartbeat
Now, the only thing picking up pace is his heart rate.
Anchored to the floor, Peter Gauger from the DLR Institute of
Aerospace Medicine stands next to the astronaut, and gently
guides him away from the ceiling, in preparation for the transi-
tion to double gravity. The sensors on Schlegel’s body can only
record the force with which his heart pumps blood into the
large vessels with each beat if he is allowed to float entirely free
of outside interference. He has already completed this experi-
ment once, in Spacelab during the D2 mission. The plan now is
to optimise the simple technique of ballistocardiography for use
on the International Space Station, ISS. Several countries are
represented on the scientific team; United States, Belgian and
German researchers work hand in hand. “Next, we want to, on
the ISS, verify whether spending several months in space affects
the way the heart works,” says Gauger.
On the dot of nine, the doors closed behind the scientists
and the ZERO-G took off on its parabolic flight. The European
Space Agency, ESA, and the French Space Agency, CNES, have
conducted 120 parabolic flight campaigns since 1984. The
German Aerospace Center has been doing this since 1999. In
total, they have completed 1400 experiments in 28 years while
flying in zero gravity in the aircraft. This time, there are 11 ex-
periments on board the ZERO-G.
A weed as test specimen
The second parabola begins. Svenja Fengler has anchored
herself to the aircraft using the foot restraints – both gloved
hands in a box of specimens.
Arabidopsis thaliana
is set to
receive an injection of chemicals. The unprepossessing weed
is almost predestined for parabolic flights: “The genome has
been fully sequenced,” says the scientist from the University
of Tübingen. Biologists are well acquainted with thale cress –
which is why it is perhaps best suited to revealing the genes
A break comes after the sixth parabola. For five minutes,
the ZERO-G will fly like a normal airliner. Restlessness spreads
across the aircraft. Specimens are exchanged, procedures
improved and for just a moment, preliminary conclusions are
drawn. For some on board, these five minutes offer a precious
break allowing their bodies to recover. It is practically impossible
to influence how one’s balance organ responds to the ups and
downs. The first scientist in Alexander Piehl’s team is lying flat
on the floor. “It’s far better this time than in previous flights,”
he asserts. Another five parabolas and he will ask the on-board
doctor Thierry Leraitre to administer a further injection to combat
nausea – before spending the subsequent 20 parabolas exam-
ining the behaviour of nonlinear waves in dusty plasma during
weightlessness. “It is important to conduct experiments in
microgravity,” he says. “And it is still fun, even if it leaves you
feeling a bit sick.”
It is a rare thing indeed for anyone to refuse the opportu-
nity to conduct experiments in circumstances that are so rarely
on offer. The ZARM drop-tower in Bremen can offer four to nine
seconds of weightlessness, while a high-altitude research rocket
delivers six to 12 minutes. All that comes after that to obtain
weeks or even months of weightlessness are satellites and the
International Space Station. “Parabolic flights are a good occa-
sion to conduct experiments in the absence of gravity for multiple
periods of 22 seconds, without needing long periods of prepa-
ration,” says Ulrike Friedrich, Project Manager for Parabolic
Flights at DLR. So anyone wishing to be on board has to convince
a jury of outside experts. “Many scientists devise a whole series
of experiments and fly with them on several campaigns.”
Treacherous exercise in balance control
Ramona Ritzmann from the Albert Ludwig University
of Freiburg is one of these researchers. The sport scientist is
floating professionally while her test subject in zero gravity
balances on one leg. The board he is standing on is designed to
surprise; sometimes it lurches forward, other times it slips to the
side. Astronauts living and working in space experience deterio-
ration in the control of movements and balance. Upon their
return to Earth, they find they are barely able to walk or stand
upright without assistance. “You lose a lot of skills in space,”
says Ritzmann. The test subject, Yannik Kupfer, struggles for
stability. Each attempt to maintain balance on the treacherous,
freely oscillating board provides the sport scientists with data on
his muscle activity and reflex pathways. The phase of double
gravity begins. Yannik flops back into his seat while Ritzmann
hops cumbersomely up and down. Novices are urgently advised
to rest during these hyper-G phases, and most certainly without
moving their heads. “Thankfully, it doesn’t bother me at all,”
says the sport scientist. In future, people undergoing rehabilita-
tion will benefit from the results of this experiment.
The 31 parabolas are over faster than expected. The red
digital display in the aircraft records each single parabola. Finally,
the last cycle comes and goes. Everyone on board returns to
their seat. Like in any airline flight from Cologne to Berlin,
passengers are required to fasten their seat belts. Zero gravity
conditions prevailed for a total of 682 seconds. Back in the
arrivals hall, conclusions are drawn. One team experienced
difficulties exchanging the specimens between the individual
parabolas, while another team had found the first parabola
to be too fast. The crew from the University of Freiburg had
struggled with a defective cable, while the team from the DLR
Institute of Materials Physics in Space had encountered difficul-
ties with the new X-ray system, X-Rise, on their maiden flight.
And the scientists who spent the flight monitoring the weeds
can look forward to months of evaluating tens of thousands of
genes back in their home university. Hans Schlegel’s heartbeat
is revealed to the scientists as a zigzag line. He will spend the
following day breathing in and out in regular patterns, instead
of on board the aircraft. The plane itself now stands parked in
front of the hangar, its door closed. A new day of flights begins
at 06:00 the next morning – the X-ray device will get to work,
another test subject will try to keep his balance, and dusty plas-
ma will once more form clouds, waiting to be photographed.
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Balance in microgravity. The team from the University of Freiburg
examines movement and balance control to help astronauts and
patients undergoing rehabilitation.
Research without gravitation – while the subject performs various
tasks on the screen, the researcher from the German Sport
University drifts above his control laptop.
The extraordinary
manoeuvres are
carried out in
specially designated
areas
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