Under close observation
In the meantime, Maria Talapina and Christoph Freukes
prepare the capsule. At the base of the metal container, padding
ensures that MASCOT is not damaged during the abrupt dece
leration following the rapid descent. Four small cameras will
monitor the lander from every direction during the flight in
microgravity, and will record the events taking place inside the
capsule. Two additional high-speed cameras on the outside of
the capsule will also be transmitting the first live pictures during
the descent – these will be displayed live on a screen in the
control room. Bundles of fine cables and connectors are wound
along the cylinder’s exterior. Christian Grimm and Artur Hass
mount the supporting structure on the lander. In free fall, this
part will simulate the spacecraft from which MASCOT will be
ejected at a height of 100 metres.
Everything is ready. Four pairs of hands gently slide the
asteroid lander into the cylinder. Maria Talapina lets the heavy
cover slide downwards on its hoist. Metal contacts metal. It is
now time for the DLR engineers to make the final adjustments
before leaving their valuable cargo in the hands of the team
operating the drop tower. Screw after screw is tightened. The
first data from the lander is displayed on the screens. “Some-
thing is not right,” shouts Freukes. And then it happens – one
of the wires on the exterior of the cylinder breaks off. Christian
Grimm rummages in the drawers looking for a tool. Together
with Artur Hass, he works his way through the cable harness to
the damaged wire. They both completed training as electrical
technicians before going on to study aerospace engineering,
and this is now being put to good use on the asteroid lander.
Tension dominates the atmosphere for a few moments. The test
must proceed, but the defective wire is holding everything up.
Ten minutes later the wire is repaired and the cylinder is ready
to be handed over.
As of this moment, the fate of MASCOT lies in the hands
of drop tower operators Torsten Lutz and Dieter Bischoff. The
DLR engineers must get used to standing on the sidelines.
When the asteroid lander touches down on 1999 JU3 in 2018,
the distance to Earth will be too great for real-time radio
commands, so MASCOT will have to carry out its mission
completely autonomously. Lutz and Bischoff roll the test unit to
the drop tower, seal the capsule and raise it to the top using a
chain. Eighteen powerful pumps spring to life with a hum.
Testing the MASCOT asteroid lander
By Manuela Braun
Free-falling scout
In 2014, the Japanese Hayabusa-2 spacecraft will begin its journey to asteroid 1999 JU3. On board will be the Mobile
Asteroid Surface Scout, MASCOT, an asteroid lander. The main excitement for DLR engineers will begin in 2018, when the
lander detaches itself from the mothercraft, touches down on its target, moves across the surface by ‘hopping’ and
contributes to the first ever measurements on the surface of an asteroid. First, however, MASCOT must undergo
numerous tests to prove that it is capable of completing the trip through space and the separation from Hayabusa-2. The
DLR Magazine was in Bremen when MASCOT was ‘launched’ and, shortly afterwards, separated from its mothercraft –
on a smaller scale, but as realistically as possible.
The testing of the MASCOT separation mechanism is
taking place inside the drop tower at the Center of Applied
Space Technology and Microgravity (Zentrum für angewandte
Raumfahrttechnologie und Mikrogravitation; ZARM) at the
University of Bremen. A capsule containing the asteroid lander
will be dropped from the top of the tower. As the experiment
falls towards Earth, it will experience a few seconds of micro-
gravity. One of the most critical moments of the lander mission
will take place in the human-sized metal capsule. The release
mechanism must gently push MASCOT away from Hayabusa-2,
overcoming any friction in the separation process, and out
towards the surface of the asteroid.
Christian Grimm from the DLR Institute of Space Systems
examines a small black plastic component. As he presses on the
part connecting two small plastic arms, there is a gentle click.
“Actually, it is a fairly simple spring,” says the Test Manager.
Nonetheless, this spring will determine whether or not a lander
will touch down on an asteroid and acquire data on its surface –
data that will allow researchers to learn more about these
celestial bodies and the evolutionary history of the Solar System.
Many things might go wrong; for example, MASCOT
could tilt and become stuck as it separates from the Japanese
mother craft. This was the case during the first test in the drop
tower. Grimm smiles and shrugs his shoulders. You can only
learn from such mishaps. As a result, the second test run on the
following day was much better – everything went perfectly.
Today, the model of the shoebox-sized lander is back in the
cylinder, ready to descend to Earth in free fall once again.
A small team is simulating the flight over the asteroid.
Christian Grimm, Artur Hass, Maria Talapina and Christoph
Freukes work calmly and with intense concentration. Grimm
and Hass carefully measure the lander. The black struts give it
the look of a tiny half-timbered house. The Test Manager writes
down number after number on a list. The more precisely the
model’s centre of gravity is calculated, the better the test results
can be compared with the computer simulations. Grimm taps
on the black structure that protects the interior of the lander.
“You could, of course, make this out of aluminium as well, but
carbon fibre reinforced composite is much lighter and yet
extremely stable – and with this compact lander, every gram
counts.” The container that will carry four instruments to the
asteroid’s surface measures just 30 by 30 by 20 centimetres.
What goes up must come down. DLR engineers follow the
path of the metal cylinder in which the MASCOT asteroid
lander descends 110 metres to the ground.
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