Airborne Launched microsat

AVIO-ELV are studying ways to launch a small rocket from an air-carrier, looking at a possible use for out-of-area tactical missions. The released rocket would be activated to release a payload of 100 kg maximum at an altitude comprised between 300 and 500 km The payload would essentially consist of a microsatellite suitably equipped with instruments capable of providing useful information to the locally deployed national resources.

The Prime asked Spacesys to outline a mission and a spacecraft plus payload capable of meeting the customer expectations while staying within the tight limits imposed by the carrier-rocket.    

After some iterations we defined an optical, panchromatic, observation mission combining the features of a synoptic imaging with ground resolution per NIIRS level 3 over swaths about 900 km wide,  with a precommanded, selective, imaging with ground resolution per NIIRS level 4 over swaths in the 15-20 km range.

The payload consists of an array of six fixed-mounted professional cameras for synoptic imaging and one 25 cm diameter telescope with an F#3.6 for the high-resolution imaging tasks. All cameras operate in a pushbroom mode. The spacecraft implements a three-axis attitude control with generous  steering capabilities around the roll axis for off-nadir imaging.

On board compression (at least 5:1 or more)  is envisaged to reduce the data volume to be relayed to ground via a directional antenna. The delay between image takes and transmission to ground wll depend on where the data stations will be located: several alternatives were considered by the Prime but this is an aspect to be deepened because it impacts directly the size of the  the on-board memory presently estimated to be in the four gigabit range

The feasibility study showed that the payload can be allocated inside a microsat having dimensions close to those of the Ponysat satellite. The short duration mission of six months or less allows to avoid any drag compensating propulsion system. A power budget around 50 W was estimated to be sufficient for the planned  low operational duty of the optical payload. The study also confirmed that using COTS devices and equipments, the microsat should stay within the initially allocated 60 Kg