Specifications

Background
5
All these experiences led to the idea to develop a common test bed capable to
replicate all the functions that will be available on the ALMASat-EO microsatellite in an
operational environment different from a standard laboratory equipment.
The idea has subsequently evolved in a more generic and expandable aerial platform,
not only a test bed, able to manage remote sensing instrumentations and equipped with
attitude and positioning sensors for high accuracy data georeferencing. The FASTER
system, that will be described in the following Chapters, aggregates all the results
obtained with the previous projects in a unique system that has diversified applications.
2.1 AMSC
The AMSC (ALMASat MultiSpectral Camera) is a spaceborne camera that will fly
onboard ALMASat-EO, the second microsatellite of the University of Bologna. The idea
was to extend the capabilities of the ALMASat-1 standard bus in order to achieve Earth
observation capabilities, to do this a completely new device has to be developed. The
development of the optical payload for an Earth observation microsatellite mission is
always difficult due to the high number of constrains that have to be considered when
dealing with the reduced dimensions and low-power available on the spacecraft. As a
matter of fact, most of the widely available systems presently used to acquire Earth
images, as pushbroom or wiskhbroom scanners, cannot be used onboard a microsatellite
mainly because of the high power and data rate they require.
On the other hand, a common still camera with no moving parts and a discrete mode
of operation instead of a continuous one (scanner), seems to be the right choice in order to
reduce power consumption and complexity of the system; in particular, the main
advantage of this system is that the linear sensor is replaced by a two-dimensional ones
able to acquire instantaneously an entire scene, thus preserving the correct geometry and
reducing the number of frames necessary to acquire the target area. Moreover, a low
frame rate allows the use of a Full Frame CCD ensuring the highest resolution. The
camera has been designed in order to fit the available space dedicated to the payload,
onboard the ALMASat-EO spacecraft bus, which consists in an additional cube
(300x300x300 mm) placed in the lower part of the original ALMASat-1 bus.
In the first phase, major efforts was devoted to the definition of the system
requirements and the selection of suitable enabling technologies which could allow the
use of imaging Earth sensors on board an Earth orbiting spacecraft. The type of sensor