The Satellite - SSETI-Express
The satellite and its mission in short
SSETI-Express is a so called "Micro-satellite", its dimensions are
60x60x80cm and it weighs in at 62kg which is 1kg heavier than the
satellite, which was launched in 1999. The SSETI-Express project
started in January 2004 and peaks with its launch on the 27th of
September 2005. This short schedule makes it the fastest developed
micro-satellite mission in history!
The satellite has been built by students from 14 different
universities across Europe. The project has been supervised by the
European Space Agency (ESA
students have been organised in 12 different teams
which has cooperated during the project. Coordination has happened
using the Internet as a tool for meeting, discussion and information
sharing. The satellite has been integrated and tested at the European
Space Technology and Test Centre (ESTEC) in Holland, where the
students have been working during short stays.
As part of its mission SSETI-Express carries into orbit three small
"passenger satellites" each weighing a kilo. These are built by
students from Norway, Germany and Japan respectively. These passenger
will be deployed 74 minutes after SSETI-Express has been put in orbit.
SSETI-Express and its passengers will reach orbit with the help of a
Russian "Cosmos-3M" launcher and will share the launch with the
"Disaster Monitor Constellation 3" from Surrey Satellite Technology
Limited (SSTL). The orbit will be circular and sun synchronous with an
altitude of 686km.
The SSETI-Express mission has the following mission objectives:
• To demonstrate that a distributed student group can carry out a
• To deploy three cubesat passengers
• To take pictures of the Earth
• To perform technical experiments with student built hardware in
• To function as a radio-relay for radio amateurs worldwide
Also see the SSETI-Express
for more information or the SEOR
page on SSETI-Express
for a concise technical description
Description of contributions from students from Aalborg University
The following paragrpahs provides descriptions of the subsytems that
students from Aalborg university have contributed with.
The On-Board Computer and Software
With Karl in the lead the group has developed the
micro-computer which are situated in the midst of the
spider-web of wires that connects the on-board systems of
SSETI-Express. The computer, and the software that the group
has developed for it, controls everything the satellite does
and stores all the generated data from the on-board
instruments, so that they can be downloaded to ground.
As the computer is a central piece of the satellite jig-zaw then Karl
has been in Holland many times during the project in order to help
other teams interface to the computer and make corrections to the
For the same reason Karl is also one of the project participants that
knows the satellite best. Therefore he is also chosen to be on the
team that travels to Plesetsk in Russia in order to perform the
final preparations and checkout of the satellite. Karl says about
the time leading to launch: "Now we are waiting to see if we have
built something that can survive the launch and the space tough
space environment. SSETI-Express can do it, just wait and see!".
The group graduated in the summer 2005 as master candidates in
"Intelligent Autonomous Systems" and Karl has continued his studies
as a master student.
Attitude Determination and Control System
The satellite cannot point in a random direction! For example
its antenna should point towards the Earth when it flies over
the groundstation. This task has been solved by Lars. He has
been involved with the project since its start as whispers in
the corridors of ESTEC. The Task has been solved using a
combination of permanent magnets and electromagnetic coils,
which interacts with the magnetic field of the Earth. In
addition to controlling the attitude it is also necessary to
actually know which way the satellite is pointing this is done
using sensors that measures the direction of the magnetic
field of the Earth relative to the satellite and the direction
to the sun relative to the satellite.
In addition to the ACDS task then Lars has also been helping the
"systems engineering team", which are responsible for the overall
design of the satellite. Here he has performed advanced
multi-disciplinary simulations of the on-board systems in order to
estimate how they will cooperate in space. Finally he will be
responsible for coordinating the operation of the satellite during
the first few critical days following launch until the launch
campaign team returns from Russia.
"To design a satellite is a creative, multi-disciplinary and
multicultural process, and it is very far from the conception that
some have about 'Space nerds'. And then it is great fun!" says Lars.
Lars graduated in the summer of 2004 with a master in "Intelligent
Autonomous Systems" and has hereafter been a PhD student at Aalborg
university where he studies advanced autonomy concepts for future
space missions. He was also involved with the AAU-cubesat satellite
launched in 2003.
An important part of the payload of the satellite is the digital
camera which has been developed at Aalborg University in close
coorporation with the local company
Devitech . The camera will
be used to take pictures of northern europe and give the students and
other interested people a small view at how our planet looks from
Originally the camera was not build for the Express satellite but
instead for the much smaller AAU
Cubesat which is a 1kg 10x10x10 cm size satellite which was built
at Aalborg University and launched 2 years ago. However the camera was
never tested and it was decided to make a severely modified version
which could be used on Express which Morten has been working on.
The camera is a 1280x1024 (1.3 Mpixel) colour camrea with a small zoom
lens that enables it to take pictures of the earth which measures
about 400x300 km. This measn that it cannot take pitures of your
backyard or peoples license-plates as may knows it from Hollywood
"As a study project the task of building a satellite is close to
ideal, but it is also very demanding. When the satellite has been
launched it is flying around 600 km about us you cannot just go
tighten that small but very very important screw some one had
forgotten needed tightening. If you for get that or one of a 1000
other small things everything has been futile".
Morten graduated as Master of Science in "Intelligente Autonome
Systemer" in the summer 2004 and was thereafter employed at Aalborg
University as a PhD student where he works with autonomous
helicopters which will be used for mine-detection. He was very much
involved in the AAU Cubesat project.
Groundstation in Aalborg and at Svalbard
There is not much point in having satellite that one cannot
communicate with. Therefore the group has developed a groundstation
consisting off antenna, dish, radio and computers for controlling
it. The primary groundstation is placed on the roof of Aalborg
university where it has a good view towards space.
In addition to the station in Aalborg then the group has also
cooperated with a professional groundstation at Svalbard in
Norway. Here high north the conditions for communicating with
satellite are especially good. Some of the equipment at Svalbard has
been modified in in order to make it compatible with the
The work on the groundstations has offered the opportunity to work
with radio-amateurs from around the world. Kresten, who is become a
bit of radio-amateur himself, says: "It's a very giving experience
to cooperate at an international level on a project like
SSETI-Express. One get to know many exciting people and shares many
good times with them".
The group is currently in their last year of studies.
Mission Control Centre Software
In order to be able to command the satellite and display its
status, the group has developed a piece of software that acts
as "command console" for the satellite. It operates on top of
The software is also responsible for safely archiving the data that
are downloaded from the satellite in a database, such that they can
be used for later analysis. The software makes use of both the
groundstations in Aalborg and at Svalbard.
Their software consists of a server part and a client part. The
server runs on a computer at Aalborg university, while the client
can be run from any computer in the world that has a
web-browser. Martin Green says: "The most exciting experience that I
have had with SSETI-Express was when I has to travel to Svalbard in
order to agree with the experts there how our software could
interconnect to their network".
The group is currently in their last year of studies. Martin and
Martin will spend the autumn semester as interns at ESTEC in
Holland where they will work on satellite formation control. Rasmus
will spend the semester at Stanford University in California where
he will study in their micro-satellite department. Kristian and Axel
will be in Canada where they will work on "Discrete Event Systems"
with application to satellite radio communication.