NARCISO: a microsatellite that takes pictures of itself

In the early nineties the Group of Astrodynamics of the University of Roma “La Sapienza” (GAUSS), established the UNISAT program at the School of Aerospace Engineering of Roma with the aim to design, manufacture and operate in orbit small educational satellites involving students, researchers and professors in a real space project. In the framework of this program four satellites have been launched in 2000, 2002, 2004 and 2006 from Baykonour Cosmodrome using DNEPR launch vehicle. Next satellite of UNISAT series, UNISAT-5, will have attitude stabilization system based on the well known gravity gradient effect by exploiting a new kind of deployable boom. The design of this deployable boom, based on harmonic steel tape coil spring, is inspired to the booms developed for the SIRDARIA deorbiting system boarded on UNISAT-4. The same concept has been adapted to the attitude control of UNISAT-5, by increasing the boom length up to three meters. The boom deployment is going to be tested on board REXUS rocket. This is a small ballistic rocket, launched from ESRANGE base on the framework of ESA REXUS/BEXUS program, used to perform small experiments under microgravity conditions. The design, realization and tests of the boom are depicted in the first part of the paper. The second part of this paper deals with design and realization of the tip-mass. It is a one kilogram, ten by ten centimeters, autonomous payload, capable to perform simple experiments such as taking pictures of the mother satellite, which will be transmitted to the mother satellite itself using a wireless connection and then downloaded to the ground station. The tip-mass, named NARCISO, is realized by rapid prototyping technique, in ABS plastic material. Exploiting this technique, a complete structure capable of hosting all subsystems required by a small satellite, from electronic board to antennas and solar cells, can be manufactured in a short time (about 23 hours) with reduced costs. Moreover, almost any shape and mechanical detail within 0.3 mm accuracy (the height of the single layer) can be obtained. The UNISAT-5 satellite and the NARCISO tip-mass will take pictures of each other. In this way, the UNISAT solar cells degradation can be photographed and the ABS degradation can be also monitored by remote visual inspection.