Coordinate two imaging spacecraft

ALSAT-2A launched on 12 July 2010 and ALSAT-2B on 26 September 2016. This Algerian program pursues high-resolution Earth imaging, distinct from Alsat-1’s medium-resolution lineage and Alsat Nano’s technology experiments. Sharing the Alsat name does not mean interchangeable cameras or missions.

Airbus describes a contract covering both spacecraft and training: thirty ASAL engineers joined the Toulouse work on the first spacecraft, while ASAL integrated the second in Oran. That progression links an international engineering partnership to a national ability to assemble and operate a satellite. Hardware delivery is one milestone; sustaining procedures, staff knowledge and ground operations is a continuing responsibility.

ASAL reports that ALSAT-2B reached its operational orbit in December 2016, with a phase separation of 186 degrees from ALSAT-2A. Phase describes their relative positions along an orbital cycle. Two vehicles can offer more tasking opportunities, but a gap measured around the orbit is not automatically the revisit time for a particular city.

Consider an idealized circular orbit with a 100-minute period. Traveling through 186 degrees takes 186/360 × 100, about 51.7 minutes. The complementary 174 degrees takes about 48.3 minutes. This deliberately simplified calculation describes along-orbit spacing only. Earth rotates underneath, and the same ground target may not be in a usable viewing position when either spacecraft reaches that orbital location.

Orbit spacing is not ground revisit

ASAL lists 2.5-metre panchromatic sampling, 10-metre multispectral sampling and a 17.5-kilometre swath for the system. Panchromatic measurements emphasize spatial structure; separate visible and near-infrared bands support spectral comparisons. A task also needs an observation date, acceptable viewing geometry, cloud conditions and a suitable processing level.

Imagine a city planner requesting a construction-site update before a meeting. A potential overpass after the meeting misses the deadline; a cloudy image before it may hide the site. Scheduling both spacecraft can improve the set of choices without guaranteeing success. A defensible service report distinguishes an available opportunity, a scheduled scene, an acquired observation and a checked product.