German Mars Balloon Mission Advances

ARCHIMEDES on the track
Sven Knuth
President, Mars Society Deutschland
September 26, 2004

Today on a press conference in Bochum, Germany, the private financed
Mars balloon mission P-5A/ARCHIMEDES was presented. The huge press
coverage exceeded every expectation. All newspapers and magazines, TV
and radio stations covered this visionary idea. Especially articles
in business newspapers like Handelsblatt will help rise the needed
funding.

The AMSAT P5-A is destined to enter an orbit around the planet Mars.
This spacecraft will then transmit scientific data to Earth – data
from experiments on-board P5A as well as - via its repeater function -
from the ARCHIMEDES balloon. This probe will also take with
ARCHIMEDES on its way to Mars after launch with Ariane 5 where it is
released and enters atmosphere.

Extensive studies conducted throughout the past years have indicated
that both the concept of inflating the balloon during descent as well
as the concept of inflating the balloon from the ground poses immense
technical hurdles that need to be overcome. Both result in extremely
complex spacecraft designs and mission sequences that cannot be
realized by the project Archimedes team, if the proposed launch
window of 2009 is to be used. Hence, a different concept has been
developed, whereby the balloon is to be inflated out in space while
approaching the planet, and subsequently used as a hypersonic drag
device to slow the vehicle down enough for descent to its operating
altitude. This way, the ARCHIMEDES mission will also demonstrate the
technology for inflatable atmospheric drag devices on Mars. It
provides room for the significant technology experiment COMPARE, the
scope of which is to gather crucial hypersonic flow data during entry
of a large body into the Martian atmosphere. This data will be
invaluable to future heavy landers and aero-assisted manœuvres.

It also provides the unique opportunity to measure the density profiles
of the upper layers of the atmosphere with accelerometers due to the
spacecraft's very low ballistic coefficient.

In addition to the aforementioned baseline mission scenario, two
other scenarios are currently considered. The first option would be
to target mission duration of one sol. This would drop the
requirement for night time survival, and thus also reduces the
requirements for power and thermal control. Since the mission could
be flown with primary batteries only, solar cells would not be
needed, and the suspension bridle also becomes unnecessary. Most
important, however, less internal overpressure would be required,
since the balloon would be allowed to sack at night, and hence the
floatation gas could cool and contract below ambient pressure. But
this in turn lowers the skin load when the floatation gas pressure
rises upon entry heating. It should be noted here that all mission
requirements including the demonstration of sustained floatation in
the Martian atmosphere would be fulfilled by this option, albeit
being less desirable due to the short mission lifetime.

The second option would go even further and allow the balloon to
descent directly to the ground, a scenario referred to as the "Direct
To Ground Scenario" (DTG). In addition to the first option, this
option would employ a simpler, more common and more robust, yet also
heavier balloon skin material which is not able to sustain floatation
but causes the mission to descent during a prolonged period of about
two hours (as compared to classic entry bodies that travel through
the atmosphere all the way to the ground within a few minutes).

For more information visit the project website (there is an English
version available):
http://archimedes.marssociety.de/

About Mars Society Germany

The German Branch of the Mars Society is
a registered non-profit organization with 200 members. The main focus
is on promoting human exploration of space with the main focus on
Mars. With aggressive public relations initiatives and also political
outreach the German participation in international efforts to reach
the Red Planet shall be achieved.

Sven Knuth
President Mars Society Deutschland e. V.

http://www.marssociety.de/

For further information about the Mars Society, visit our website at
<a href="http://www.marssociety.org