Skip to main content

AltiCube+ - An Aggregated CubeSats Swarm for Long Fixed-baseline Radar Altimetry



Prime contractor
Organisational Unit
Activity Type
02 October 2023

Duration: 12 months


Spaceborne radar altimeters have proven to be effective tools for measuring global water levels. In the coastal zone and over inland water bodies, increased cross-track resolution, better spatiotemporal coverage, and increased altitude accuracy are essential. Radar interferometry can be used to obtain sub-kilometer resolution over a swath at the expense of additional transmit power and a sufficiently long baseline to accommodate at least two antennas. A good example is the NASA’s SWOT, a satellite with two 5-meters radar altimeter antennas on a 10-meters long boom, paid with 15 years’ development time and more than one billion dollars cost. As a consequence, it is unlikely that oceanographers will ever get a much wanted high spatiotemporal revisit rate. However, if the cost of a single altimeter can be significantly reduced, then launching multiple systems to obtain a constellation with good spatiotemporal coverage could overcome the problem. Instead of a distributed interferometric swarm requiring extremely high accurate time/attitude synchronizations and centimeter level formation maintenance, hereby we propose AltiCube+, a low-cost long fixed-baseline radar altimeter solution using an aggregated CubeSat swarm. Based on this solution, various altimeter concepts including off-nadir SARIn and a Multiple-Input and Multiple-Output (MIMO) will be explored, aiming at sub-kilometer level cross-track resolution. The uniqueness of AltiCube+ is on the potential scientific opportunities brought by the fixed long baseline (10 m and above) and the sustainability due to its significantly low cost (~20 MEuros) and short development lifecycle (3 years for IOD, In Orbit Demonstration). If budget allows, multiple AltiCube+ systems with same or different altimetry capabilities can form a constellation to dramatically reduce the revisit time and, therefore, provide much better spatiotemporal coverage.

Contract number
OSIP Idea Id
Related OSIP Campaign
Innovative Mission Concepts Enabled by Swarms of CubeSats
Main application area
Topical cluster
AltiCube+ - An Aggregated CubeSats Swarm for Long Fixed-baseline Radar Altimetry