whether it has landed the right way up, and its hopping mecha-
nism to correct its attitude if necessary. The on-board autonomy
will then put the scientific instruments into operation. Over the
following 16 hours – two full asteroid days and nights – MASCOT
will move to various measurement sites using the hopping me-
chanism. These jumps across 1999 JU3 will range between a few
metres to 100 metres in length.
Here on Earth, for the asteroid lander, the end of one
test means it is time for another. Once again, MASCOT will be
released from the mother spacecraft and fall through micro-
gravity. Once it has survived that fall, the next challenge follows
– will it survive the extreme temperatures in space? At Bremen,
space will once again be simulated to answer this question –
in the thermal vacuum chamber at the DLR Institute of Space
Systems.
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More information:
Within two hours they will create a vacuum in the entire tower –
air resistance cannot be allowed to interfere with the free falll.
Launch conditions on a shaker
At the same time, in another building, another test item is
being ‘launched into space’. An indefinable sound comes from
a room in which a model of MASCOT is mounted on a shaker
table. What seems like a mix of grinding and screeching pene-
trates through the glass in front of which Olaf Mierheim sits
with his team. The researcher from the DLR Institute of
Composite Structures and Adaptive Systems is subjecting the
lander to the mechanical environment it will experience during
launch. MASCOT must be capable of withstanding the vibra-
tions from the launcher’s engines as well as acoustically induced
vibrations in this environment without suffering any damage.
Japanese colleagues at the JAXA space agency have supplied
detailed information about the loads that MASCOT will be
subjected to during the launch. A wide range of frequencies will
affect the asteroid lander simultaneously – loads that will push
the materials to their physical limits. Test Managers Christian
Grimm and Olaf Mierheim put on ear protectors and enter the
room containing the shaker table. The unpleasant noise gets
louder for a moment. But MASCOT seems unharmed. The two
colleagues will soon see from the display on the monitor in the
control room whether the interior of MASCOT and the swing
arm that will be expected to make the lander ‘hop’ have survived
without damage. Everything looks OK. The next test run can be
prepared.
Countdown to release
In the drop tower, everything is set for the critical moment.
Torsten Lutz sits at the console in the control room. On the large
screen, the capsule can be seen 110 metres up. Christian Grimm
and Artur Hass go to their control console. In the seconds that
follow, Bremen will become outer space, as an asteroid lander
separates from its mother craft and falls towards an asteroid.
Project Leader Tra-Mi Ho has entered the control room, as have
several other members of the MASCOT team, to follow the
flight in microgravity. Although there is no rocket launching this
time, the tension in the control room is palpable. “Three, two,
one!” With this short countdown, the Test Manager indicates
that the capsule will begin its plunge. With the push of a button,
the capsule on the screen hurtles towards the ground at 170
kilometres per hour. The experiment lasts 4.7 seconds, as the
cylinder slams into the eight-metre-tall collector tube, where
polystyrene spheres decelerate it. “This is like a car accident,”
says Lutz. In the control room, the tension among the engineers
abates. “Yes!” says Christian Grimm, banging the palm of his
hand on the table. Everyone exhales. The short film sequence
from inside the capsule has shown that the release mechanism
worked. In space, MASCOT would now be falling towards the
asteroid from an altitude of 100 metres.
But there is still an unknown; how is MASCOT doing
inside the capsule? Once air has been allowed into the tower,
Torsten Lutz can open the huge doors. A metal ladder rises eight
metres. A sea of polystyrene spheres covers the capsule in the
collector tube. It is slowly pulled up with the chain. A waterfall
of polystyrene cascades from the slowly emerging container.
Lutz uses a high-pressure blower to remove the last spheres
from the capsule. As soon as the package has been safely
recovered and lowered down to the floor, the DLR team can
inspect the asteroid lander closely.
Successful separation
A few moments later, the time has come; Christian Grimm,
Artur Hass, Maria Talapina and Christoph Freukes loosen the final
screws and the cover is free. They are able to look inside, where
MASCOT
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MASCOT rests on its padding. “When it was released, it fell
straight down, perfectly,” the Test Manager says with delight.
The asteroid lander is sitting on the square pattern of the
padding, absolutely in line with the pattern. Grimm and Hass
gently extract the lander from the cylinder. A ripping noise can
be heard – the engineers have had to use a trick; Velcro under-
neath MASCOT has ensured that the asteroid lander was not
thrown back out of the padding and against the upper support
structure during the impact. “It would not have withstood that.”
The Test Manager slowly turns the unit from left to right. Four
pairs of eyes look enquiringly at the lightweight structure. Nothing
bent, nothing damaged? All of the struts on MASCOT look OK.
The mechanism for ejecting the lander has worked, and the
asteroid scout has survived the test.
In space, the encounter with the surface of the asteroid
will hopefully be gentle. Landing on asteroid 1999 JU3 is a cha-
llenge – there, the gravity is 60,000 times lower than that at
Earth’s surface. If the lander is going even a little too fast, it will
bounce off the asteroid and drift into space. But if everything
goes according to plan, MASCOT will use its sensors to check
Participants in the
MASCOT mission
The MASCOT (Mobile Asteroid Surface Scout) asteroid
lander is being developed at DLR. It will arrive at asteroid
1999 JU3 on board the Japanese Hayabusa-2 spacecraft
in 2018, where it will study the celestial body, which is
approximately 4.5 billion years old, and has a diameter
of roughly one kilometre. On board the lander are a
magnetometer (TU Braunschweig), a near infrared
microscope for hyperspectral imaging (IAS – CNES), as
well as an optical wide-angle camera and a radiometer
from DLR. Involved in this mission for DLR are the
Institute of Space Systems, the Institute of Composite
Structures and Adaptive Systems, the Robotics and
Mechatronics Center (RMC), the Institute of Planetary
Research and the Institute of Space Operations. CNES
contributes to the system by providing the antennae, the
power subsystem and performing the mission analysis.
MASCOT’s communication unit is provided by the
Japanese Aerospace Exploration Agency, JAXA
The MASCOT team monitors the fall in microgravity via camera images
Test Manager Christian Grimm prepares the asteroid lander for
the test in the drop tower
On the shaker, MASCOT demonstrates whether it will be able to
survive the loads it will be subjected to during a rocket launch.
The metal cylinder, with its valuable contents, is recovered from a
sea of polystyrene spheres.
Tension following the test – how well has the lander withstood the
descent?
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